diff options
Diffstat (limited to 'third_party/nix/src/libstore/build.cc')
| -rw-r--r-- | third_party/nix/src/libstore/build.cc | 4820 |
1 files changed, 4820 insertions, 0 deletions
diff --git a/third_party/nix/src/libstore/build.cc b/third_party/nix/src/libstore/build.cc new file mode 100644 index 000000000000..1f5752a168c8 --- /dev/null +++ b/third_party/nix/src/libstore/build.cc @@ -0,0 +1,4820 @@ +#include <algorithm> +#include <cerrno> +#include <chrono> +#include <climits> +#include <cstring> +#include <future> +#include <iostream> +#include <map> +#include <memory> +#include <ostream> +#include <queue> +#include <regex> +#include <sstream> +#include <string> +#include <thread> + +#include <absl/status/status.h> +#include <absl/strings/ascii.h> +#include <absl/strings/numbers.h> +#include <absl/strings/str_cat.h> +#include <absl/strings/str_format.h> +#include <absl/strings/str_split.h> +#include <fcntl.h> +#include <glog/logging.h> +#include <grp.h> +#include <netdb.h> +#include <pwd.h> +#include <sys/resource.h> +#include <sys/select.h> +#include <sys/socket.h> +#include <sys/stat.h> +#include <sys/time.h> +#include <sys/types.h> +#include <sys/utsname.h> +#include <sys/wait.h> +#include <termios.h> +#include <unistd.h> + +#include "libstore/builtins.hh" +#include "libstore/download.hh" +#include "libstore/globals.hh" +#include "libstore/local-store.hh" +#include "libstore/machines.hh" +#include "libstore/nar-info.hh" +#include "libstore/parsed-derivations.hh" +#include "libstore/pathlocks.hh" +#include "libstore/references.hh" +#include "libstore/store-api.hh" +#include "libutil/affinity.hh" +#include "libutil/archive.hh" +#include "libutil/compression.hh" +#include "libutil/finally.hh" +#include "libutil/json.hh" +#include "libutil/util.hh" + +/* Includes required for chroot support. */ +#if __linux__ +#include <net/if.h> +#include <netinet/ip.h> +#include <sched.h> +#include <sys/ioctl.h> +#include <sys/mman.h> +#include <sys/mount.h> +#include <sys/param.h> +#include <sys/personality.h> +#include <sys/socket.h> +#include <sys/syscall.h> +#if HAVE_SECCOMP +#include <seccomp.h> +#endif +#define pivot_root(new_root, put_old) \ + (syscall(SYS_pivot_root, new_root, put_old)) +#endif + +#if HAVE_STATVFS +#include <sys/statvfs.h> +#endif + +#include <nlohmann/json.hpp> +#include <utility> + +namespace nix { + +constexpr std::string_view kPathNullDevice = "/dev/null"; + +/* Forward definition. */ +class Worker; +struct HookInstance; + +/* A pointer to a goal. */ +class Goal; +class DerivationGoal; +using GoalPtr = std::shared_ptr<Goal>; +using WeakGoalPtr = std::weak_ptr<Goal>; + +struct CompareGoalPtrs { + bool operator()(const GoalPtr& a, const GoalPtr& b) const; +}; + +/* Set of goals. */ +using Goals = std::set<GoalPtr, CompareGoalPtrs>; +using WeakGoals = std::list<WeakGoalPtr>; + +/* A map of paths to goals (and the other way around). */ +using WeakGoalMap = std::map<Path, WeakGoalPtr>; + +class Goal : public std::enable_shared_from_this<Goal> { + public: + using ExitCode = enum { + ecBusy, + ecSuccess, + ecFailed, + ecNoSubstituters, + ecIncompleteClosure + }; + + protected: + /* Backlink to the worker. */ + Worker& worker; + + /* Goals that this goal is waiting for. */ + Goals waitees; + + /* Goals waiting for this one to finish. Must use weak pointers + here to prevent cycles. */ + WeakGoals waiters; + + /* Number of goals we are/were waiting for that have failed. */ + unsigned int nrFailed; + + /* Number of substitution goals we are/were waiting for that + failed because there are no substituters. */ + unsigned int nrNoSubstituters; + + /* Number of substitution goals we are/were waiting for that + failed because othey had unsubstitutable references. */ + unsigned int nrIncompleteClosure; + + /* Name of this goal for debugging purposes. */ + std::string name; + + /* Whether the goal is finished. */ + ExitCode exitCode; + + // Output stream for build logs. + // TODO(tazjin): Rename all build_log instances to log_sink. + std::ostream& log_sink() const; + + explicit Goal(Worker& worker) : worker(worker) { + nrFailed = nrNoSubstituters = nrIncompleteClosure = 0; + exitCode = ecBusy; + } + + virtual ~Goal() { trace("goal destroyed"); } + + public: + virtual void work() = 0; + + void addWaitee(const GoalPtr& waitee); + + virtual void waiteeDone(GoalPtr waitee, ExitCode result); + + virtual void handleChildOutput(int fd, const std::string& data) { abort(); } + + virtual void handleEOF(int fd) { abort(); } + + void trace(const FormatOrString& fs); + + std::string getName() { return name; } + + ExitCode getExitCode() { return exitCode; } + + /* Callback in case of a timeout. It should wake up its waiters, + get rid of any running child processes that are being monitored + by the worker (important!), etc. */ + virtual void timedOut() = 0; + + virtual std::string key() = 0; + + protected: + virtual void amDone(ExitCode result); +}; + +bool CompareGoalPtrs::operator()(const GoalPtr& a, const GoalPtr& b) const { + std::string s1 = a->key(); + std::string s2 = b->key(); + return s1 < s2; +} + +using steady_time_point = std::chrono::time_point<std::chrono::steady_clock>; + +/* A mapping used to remember for each child process to what goal it + belongs, and file descriptors for receiving log data and output + path creation commands. */ +struct Child { + WeakGoalPtr goal; + Goal* goal2; // ugly hackery + std::set<int> fds; + bool respectTimeouts; + bool inBuildSlot; + steady_time_point lastOutput; /* time we last got output on stdout/stderr */ + steady_time_point timeStarted; +}; + +/* The worker class. */ +class Worker { + private: + /* Note: the worker should only have strong pointers to the + top-level goals. */ + + /* The top-level goals of the worker. */ + Goals topGoals; + + /* Goals that are ready to do some work. */ + WeakGoals awake; + + /* Goals waiting for a build slot. */ + WeakGoals wantingToBuild; + + /* Child processes currently running. */ + std::list<Child> children; + + /* Number of build slots occupied. This includes local builds and + substitutions but not remote builds via the build hook. */ + unsigned int nrLocalBuilds; + + /* Maps used to prevent multiple instantiations of a goal for the + same derivation / path. */ + WeakGoalMap derivationGoals; + WeakGoalMap substitutionGoals; + + /* Goals waiting for busy paths to be unlocked. */ + WeakGoals waitingForAnyGoal; + + /* Goals sleeping for a few seconds (polling a lock). */ + WeakGoals waitingForAWhile; + + /* Last time the goals in `waitingForAWhile' where woken up. */ + steady_time_point lastWokenUp; + + /* Cache for pathContentsGood(). */ + std::map<Path, bool> pathContentsGoodCache; + + std::ostream& log_sink_; + + public: + /* Set if at least one derivation had a BuildError (i.e. permanent + failure). */ + bool permanentFailure; + + /* Set if at least one derivation had a timeout. */ + bool timedOut; + + /* Set if at least one derivation fails with a hash mismatch. */ + bool hashMismatch; + + /* Set if at least one derivation is not deterministic in check mode. */ + bool checkMismatch; + + LocalStore& store; + + std::unique_ptr<HookInstance> hook; + + uint64_t expectedBuilds = 0; + uint64_t doneBuilds = 0; + uint64_t failedBuilds = 0; + uint64_t runningBuilds = 0; + + uint64_t expectedSubstitutions = 0; + uint64_t doneSubstitutions = 0; + uint64_t failedSubstitutions = 0; + uint64_t runningSubstitutions = 0; + uint64_t expectedDownloadSize = 0; + uint64_t doneDownloadSize = 0; + uint64_t expectedNarSize = 0; + uint64_t doneNarSize = 0; + + /* Whether to ask the build hook if it can build a derivation. If + it answers with "decline-permanently", we don't try again. */ + bool tryBuildHook = true; + + Worker(LocalStore& store, std::ostream& log_sink); + ~Worker(); + + /* Make a goal (with caching). */ + GoalPtr makeDerivationGoal(const Path& drvPath, + const StringSet& wantedOutputs, + BuildMode buildMode); + + std::shared_ptr<DerivationGoal> makeBasicDerivationGoal( + const Path& drvPath, const BasicDerivation& drv, BuildMode buildMode); + + GoalPtr makeSubstitutionGoal(const Path& storePath, + RepairFlag repair = NoRepair); + + /* Remove a dead goal. */ + void removeGoal(const GoalPtr& goal); + + /* Wake up a goal (i.e., there is something for it to do). */ + void wakeUp(const GoalPtr& goal); + + /* Return the number of local build and substitution processes + currently running (but not remote builds via the build + hook). */ + unsigned int getNrLocalBuilds(); + + /* Registers a running child process. `inBuildSlot' means that + the process counts towards the jobs limit. */ + void childStarted(const GoalPtr& goal, const std::set<int>& fds, + bool inBuildSlot, bool respectTimeouts); + + /* Unregisters a running child process. `wakeSleepers' should be + false if there is no sense in waking up goals that are sleeping + because they can't run yet (e.g., there is no free build slot, + or the hook would still say `postpone'). */ + void childTerminated(Goal* goal, bool wakeSleepers = true); + + /* Put `goal' to sleep until a build slot becomes available (which + might be right away). */ + void waitForBuildSlot(const GoalPtr& goal); + + /* Wait for any goal to finish. Pretty indiscriminate way to + wait for some resource that some other goal is holding. */ + void waitForAnyGoal(GoalPtr goal); + + /* Wait for a few seconds and then retry this goal. Used when + waiting for a lock held by another process. This kind of + polling is inefficient, but POSIX doesn't really provide a way + to wait for multiple locks in the main select() loop. */ + void waitForAWhile(GoalPtr goal); + + /* Loop until the specified top-level goals have finished. */ + void run(const Goals& topGoals); + + /* Wait for input to become available. */ + void waitForInput(); + + unsigned int exitStatus(); + + /* Check whether the given valid path exists and has the right + contents. */ + bool pathContentsGood(const Path& path); + + void markContentsGood(const Path& path); + + std::ostream& log_sink() const { return log_sink_; }; +}; + +////////////////////////////////////////////////////////////////////// + +void addToWeakGoals(WeakGoals& goals, const GoalPtr& p) { + // FIXME: necessary? + // FIXME: O(n) + for (auto& i : goals) { + if (i.lock() == p) { + return; + } + } + goals.push_back(p); +} + +std::ostream& Goal::log_sink() const { return worker.log_sink(); } + +void Goal::addWaitee(const GoalPtr& waitee) { + waitees.insert(waitee); + addToWeakGoals(waitee->waiters, shared_from_this()); +} + +void Goal::waiteeDone(GoalPtr waitee, ExitCode result) { + assert(waitees.find(waitee) != waitees.end()); + waitees.erase(waitee); + + trace(format("waitee '%1%' done; %2% left") % waitee->name % waitees.size()); + + if (result == ecFailed || result == ecNoSubstituters || + result == ecIncompleteClosure) { + ++nrFailed; + } + + if (result == ecNoSubstituters) { + ++nrNoSubstituters; + } + + if (result == ecIncompleteClosure) { + ++nrIncompleteClosure; + } + + if (waitees.empty() || (result == ecFailed && !settings.keepGoing)) { + /* If we failed and keepGoing is not set, we remove all + remaining waitees. */ + for (auto& goal : waitees) { + WeakGoals waiters2; + for (auto& j : goal->waiters) { + if (j.lock() != shared_from_this()) { + waiters2.push_back(j); + } + } + goal->waiters = waiters2; + } + waitees.clear(); + + worker.wakeUp(shared_from_this()); + } +} + +void Goal::amDone(ExitCode result) { + trace("done"); + assert(exitCode == ecBusy); + assert(result == ecSuccess || result == ecFailed || + result == ecNoSubstituters || result == ecIncompleteClosure); + exitCode = result; + for (auto& i : waiters) { + GoalPtr goal = i.lock(); + if (goal) { + goal->waiteeDone(shared_from_this(), result); + } + } + waiters.clear(); + worker.removeGoal(shared_from_this()); +} + +void Goal::trace(const FormatOrString& fs) { + DLOG(INFO) << name << ": " << fs.s; +} + +////////////////////////////////////////////////////////////////////// + +/* Common initialisation performed in child processes. */ +static void commonChildInit(Pipe& logPipe) { + restoreSignals(); + + /* Put the child in a separate session (and thus a separate + process group) so that it has no controlling terminal (meaning + that e.g. ssh cannot open /dev/tty) and it doesn't receive + terminal signals. */ + if (setsid() == -1) { + throw SysError(format("creating a new session")); + } + + /* Dup the write side of the logger pipe into stderr. */ + if (dup2(logPipe.writeSide.get(), STDERR_FILENO) == -1) { + throw SysError("cannot pipe standard error into log file"); + } + + /* Dup stderr to stdout. */ + if (dup2(STDERR_FILENO, STDOUT_FILENO) == -1) { + throw SysError("cannot dup stderr into stdout"); + } + + /* Reroute stdin to /dev/null. */ + int fdDevNull = open(kPathNullDevice.begin(), O_RDWR); + if (fdDevNull == -1) { + throw SysError(format("cannot open '%1%'") % kPathNullDevice); + } + if (dup2(fdDevNull, STDIN_FILENO) == -1) { + throw SysError("cannot dup null device into stdin"); + } + close(fdDevNull); +} + +void handleDiffHook(uid_t uid, uid_t gid, Path tryA, Path tryB, Path drvPath, + Path tmpDir, std::ostream& log_sink) { + auto diffHook = settings.diffHook; + if (diffHook != "" && settings.runDiffHook) { + try { + RunOptions diffHookOptions( + diffHook, {std::move(tryA), std::move(tryB), std::move(drvPath), + std::move(tmpDir)}); + diffHookOptions.searchPath = true; + diffHookOptions.uid = uid; + diffHookOptions.gid = gid; + diffHookOptions.chdir = "/"; + + auto diffRes = runProgram(diffHookOptions); + if (!statusOk(diffRes.first)) { + throw ExecError(diffRes.first, + fmt("diff-hook program '%1%' %2%", diffHook, + statusToString(diffRes.first))); + } + + if (!diffRes.second.empty()) { + log_sink << absl::StripTrailingAsciiWhitespace(diffRes.second); + } + } catch (Error& error) { + log_sink << "diff hook execution failed: " << error.what(); + } + } +} + +////////////////////////////////////////////////////////////////////// + +class UserLock { + private: + /* POSIX locks suck. If we have a lock on a file, and we open and + close that file again (without closing the original file + descriptor), we lose the lock. So we have to be *very* careful + not to open a lock file on which we are holding a lock. */ + static Sync<PathSet> lockedPaths_; + + Path fnUserLock; + AutoCloseFD fdUserLock; + + std::string user; + uid_t uid; + gid_t gid; + std::vector<gid_t> supplementaryGIDs; + + public: + UserLock(); + ~UserLock(); + + void kill(); + + std::string getUser() { return user; } + uid_t getUID() { + assert(uid); + return uid; + } + uid_t getGID() { + assert(gid); + return gid; + } + std::vector<gid_t> getSupplementaryGIDs() { return supplementaryGIDs; } + + bool enabled() { return uid != 0; } +}; + +Sync<PathSet> UserLock::lockedPaths_; + +UserLock::UserLock() { + assert(settings.buildUsersGroup != ""); + + /* Get the members of the build-users-group. */ + struct group* gr = getgrnam(settings.buildUsersGroup.get().c_str()); + if (gr == nullptr) { + throw Error( + format( + "the group '%1%' specified in 'build-users-group' does not exist") % + settings.buildUsersGroup); + } + gid = gr->gr_gid; + + /* Copy the result of getgrnam. */ + Strings users; + for (char** p = gr->gr_mem; *p != nullptr; ++p) { + DLOG(INFO) << "found build user " << *p; + users.push_back(*p); + } + + if (users.empty()) { + throw Error(format("the build users group '%1%' has no members") % + settings.buildUsersGroup); + } + + /* Find a user account that isn't currently in use for another + build. */ + for (auto& i : users) { + DLOG(INFO) << "trying user " << i; + + struct passwd* pw = getpwnam(i.c_str()); + if (pw == nullptr) { + throw Error(format("the user '%1%' in the group '%2%' does not exist") % + i % settings.buildUsersGroup); + } + + createDirs(settings.nixStateDir + "/userpool"); + + fnUserLock = + (format("%1%/userpool/%2%") % settings.nixStateDir % pw->pw_uid).str(); + + { + auto lockedPaths(lockedPaths_.lock()); + if (lockedPaths->count(fnUserLock) != 0u) { + /* We already have a lock on this one. */ + continue; + } + lockedPaths->insert(fnUserLock); + } + + try { + AutoCloseFD fd( + open(fnUserLock.c_str(), O_RDWR | O_CREAT | O_CLOEXEC, 0600)); + if (!fd) { + throw SysError(format("opening user lock '%1%'") % fnUserLock); + } + + if (lockFile(fd.get(), ltWrite, false)) { + fdUserLock = std::move(fd); + user = i; + uid = pw->pw_uid; + + /* Sanity check... */ + if (uid == getuid() || uid == geteuid()) { + throw Error(format("the Nix user should not be a member of '%1%'") % + settings.buildUsersGroup); + } + +#if __linux__ + /* Get the list of supplementary groups of this build user. This + is usually either empty or contains a group such as "kvm". */ + supplementaryGIDs.resize(10); + int ngroups = supplementaryGIDs.size(); + int err = getgrouplist(pw->pw_name, pw->pw_gid, + supplementaryGIDs.data(), &ngroups); + if (err == -1) { + throw Error( + format("failed to get list of supplementary groups for '%1%'") % + pw->pw_name); + } + + supplementaryGIDs.resize(ngroups); +#endif + + return; + } + + } catch (...) { + lockedPaths_.lock()->erase(fnUserLock); + } + } + + throw Error(format("all build users are currently in use; " + "consider creating additional users and adding them to " + "the '%1%' group") % + settings.buildUsersGroup); +} + +UserLock::~UserLock() { + auto lockedPaths(lockedPaths_.lock()); + assert(lockedPaths->count(fnUserLock)); + lockedPaths->erase(fnUserLock); +} + +void UserLock::kill() { killUser(uid); } + +////////////////////////////////////////////////////////////////////// + +struct HookInstance { + /* Pipes for talking to the build hook. */ + Pipe toHook; + + /* Pipe for the hook's standard output/error. */ + Pipe fromHook; + + /* Pipe for the builder's standard output/error. */ + Pipe builderOut; + + /* The process ID of the hook. */ + Pid pid; + + FdSink sink; + + HookInstance(); + + ~HookInstance(); +}; + +HookInstance::HookInstance() { + DLOG(INFO) << "starting build hook " << settings.buildHook; + + /* Create a pipe to get the output of the child. */ + fromHook.create(); + + /* Create the communication pipes. */ + toHook.create(); + + /* Create a pipe to get the output of the builder. */ + builderOut.create(); + + /* Fork the hook. */ + pid = startProcess([&]() { + commonChildInit(fromHook); + + if (chdir("/") == -1) { + throw SysError("changing into /"); + } + + /* Dup the communication pipes. */ + if (dup2(toHook.readSide.get(), STDIN_FILENO) == -1) { + throw SysError("dupping to-hook read side"); + } + + /* Use fd 4 for the builder's stdout/stderr. */ + if (dup2(builderOut.writeSide.get(), 4) == -1) { + throw SysError("dupping builder's stdout/stderr"); + } + + /* Hack: pass the read side of that fd to allow build-remote + to read SSH error messages. */ + if (dup2(builderOut.readSide.get(), 5) == -1) { + throw SysError("dupping builder's stdout/stderr"); + } + + Strings args = { + baseNameOf(settings.buildHook), + // std::to_string(verbosity), // TODO(tazjin): what? + }; + + execv(settings.buildHook.get().c_str(), stringsToCharPtrs(args).data()); + + throw SysError("executing '%s'", settings.buildHook); + }); + + pid.setSeparatePG(true); + fromHook.writeSide = AutoCloseFD(-1); + toHook.readSide = AutoCloseFD(-1); + + sink = FdSink(toHook.writeSide.get()); + std::map<std::string, Config::SettingInfo> settings; + globalConfig.getSettings(settings); + for (auto& setting : settings) { + sink << 1 << setting.first << setting.second.value; + } + sink << 0; +} + +HookInstance::~HookInstance() { + try { + toHook.writeSide = AutoCloseFD(-1); + if (pid != Pid(-1)) { + pid.kill(); + } + } catch (...) { + ignoreException(); + } +} + +////////////////////////////////////////////////////////////////////// + +using StringRewrites = std::map<std::string, std::string>; + +std::string rewriteStrings(std::string s, const StringRewrites& rewrites) { + for (auto& i : rewrites) { + size_t j = 0; + while ((j = s.find(i.first, j)) != std::string::npos) { + s.replace(j, i.first.size(), i.second); + } + } + return s; +} + +////////////////////////////////////////////////////////////////////// + +using HookReply = enum { rpAccept, rpDecline, rpPostpone }; + +class SubstitutionGoal; + +class DerivationGoal : public Goal { + private: + /* Whether to use an on-disk .drv file. */ + bool useDerivation; + + /* The path of the derivation. */ + Path drvPath; + + /* The specific outputs that we need to build. Empty means all of + them. */ + StringSet wantedOutputs; + + /* Whether additional wanted outputs have been added. */ + bool needRestart = false; + + /* Whether to retry substituting the outputs after building the + inputs. */ + bool retrySubstitution; + + /* The derivation stored at drvPath. */ + std::unique_ptr<BasicDerivation> drv; + + std::unique_ptr<ParsedDerivation> parsedDrv; + + /* The remainder is state held during the build. */ + + /* Locks on the output paths. */ + PathLocks outputLocks; + + /* All input paths (that is, the union of FS closures of the + immediate input paths). */ + PathSet inputPaths; + + /* Referenceable paths (i.e., input and output paths). */ + PathSet allPaths; + + /* Outputs that are already valid. If we're repairing, these are + the outputs that are valid *and* not corrupt. */ + PathSet validPaths; + + /* Outputs that are corrupt or not valid. */ + PathSet missingPaths; + + /* User selected for running the builder. */ + std::unique_ptr<UserLock> buildUser; + + /* The process ID of the builder. */ + Pid pid; + + /* The temporary directory. */ + Path tmpDir; + + /* The path of the temporary directory in the sandbox. */ + Path tmpDirInSandbox; + + /* File descriptor for the log file. */ + AutoCloseFD fdLogFile; + std::shared_ptr<BufferedSink> logFileSink, logSink; + + /* Number of bytes received from the builder's stdout/stderr. */ + unsigned long logSize; + + /* The most recent log lines. */ + std::list<std::string> logTail; + + std::string currentLogLine; + size_t currentLogLinePos = 0; // to handle carriage return + + std::string currentHookLine; + + /* Pipe for the builder's standard output/error. */ + Pipe builderOut; + + /* Pipe for synchronising updates to the builder user namespace. */ + Pipe userNamespaceSync; + + /* The build hook. */ + std::unique_ptr<HookInstance> hook; + + /* Whether we're currently doing a chroot build. */ + bool useChroot = false; + + Path chrootRootDir; + + /* RAII object to delete the chroot directory. */ + std::shared_ptr<AutoDelete> autoDelChroot; + + /* Whether this is a fixed-output derivation. */ + bool fixedOutput; + + /* Whether to run the build in a private network namespace. */ + bool privateNetwork = false; + + using GoalState = void (DerivationGoal::*)(); + GoalState state; + + /* Stuff we need to pass to initChild(). */ + struct ChrootPath { + Path source; + bool optional; + explicit ChrootPath(Path source = "", bool optional = false) + : source(std::move(source)), optional(optional) {} + }; + using DirsInChroot = + std::map<Path, ChrootPath>; // maps target path to source path + DirsInChroot dirsInChroot; + + using Environment = std::map<std::string, std::string>; + Environment env; + + /* Hash rewriting. */ + StringRewrites inputRewrites, outputRewrites; + using RedirectedOutputs = std::map<Path, Path>; + RedirectedOutputs redirectedOutputs; + + BuildMode buildMode; + + /* If we're repairing without a chroot, there may be outputs that + are valid but corrupt. So we redirect these outputs to + temporary paths. */ + PathSet redirectedBadOutputs; + + BuildResult result; + + /* The current round, if we're building multiple times. */ + size_t curRound = 1; + + size_t nrRounds; + + /* Path registration info from the previous round, if we're + building multiple times. Since this contains the hash, it + allows us to compare whether two rounds produced the same + result. */ + std::map<Path, ValidPathInfo> prevInfos; + + const uid_t sandboxUid = 1000; + const gid_t sandboxGid = 100; + + const static Path homeDir; + + std::unique_ptr<MaintainCount<uint64_t>> mcExpectedBuilds, mcRunningBuilds; + + /* The remote machine on which we're building. */ + std::string machineName; + + public: + DerivationGoal(Worker& worker, const Path& drvPath, StringSet wantedOutputs, + BuildMode buildMode); + + DerivationGoal(Worker& worker, const Path& drvPath, + const BasicDerivation& drv, BuildMode buildMode); + + ~DerivationGoal() override; + + /* Whether we need to perform hash rewriting if there are valid output paths. + */ + bool needsHashRewrite(); + + void timedOut() override; + + std::string key() override { + /* Ensure that derivations get built in order of their name, + i.e. a derivation named "aardvark" always comes before + "baboon". And substitution goals always happen before + derivation goals (due to "b$"). */ + return "b$" + storePathToName(drvPath) + "$" + drvPath; + } + + void work() override; + + Path getDrvPath() { return drvPath; } + + /* Add wanted outputs to an already existing derivation goal. */ + void addWantedOutputs(const StringSet& outputs); + + BuildResult getResult() { return result; } + + private: + /* The states. */ + void getDerivation(); + void loadDerivation(); + void haveDerivation(); + void outputsSubstituted(); + void closureRepaired(); + void inputsRealised(); + void tryToBuild(); + void buildDone(); + + /* Is the build hook willing to perform the build? */ + HookReply tryBuildHook(); + + /* Start building a derivation. */ + void startBuilder(); + + /* Fill in the environment for the builder. */ + void initEnv(); + + /* Setup tmp dir location. */ + void initTmpDir(); + + /* Write a JSON file containing the derivation attributes. */ + void writeStructuredAttrs(); + + /* Make a file owned by the builder. */ + void chownToBuilder(const Path& path); + + /* Run the builder's process. */ + void runChild(); + + friend int childEntry(void* /*arg*/); + + /* Check that the derivation outputs all exist and register them + as valid. */ + void registerOutputs(); + + /* Check that an output meets the requirements specified by the + 'outputChecks' attribute (or the legacy + '{allowed,disallowed}{References,Requisites}' attributes). */ + void checkOutputs(const std::map<std::string, ValidPathInfo>& outputs); + + /* Open a log file and a pipe to it. */ + Path openLogFile(); + + /* Close the log file. */ + void closeLogFile(); + + /* Delete the temporary directory, if we have one. */ + void deleteTmpDir(bool force); + + /* Callback used by the worker to write to the log. */ + void handleChildOutput(int fd, const std::string& data) override; + void handleEOF(int fd) override; + void flushLine(); + + /* Return the set of (in)valid paths. */ + PathSet checkPathValidity(bool returnValid, bool checkHash); + + /* Abort the goal if `path' failed to build. */ + bool pathFailed(const Path& path); + + /* Forcibly kill the child process, if any. */ + void killChild(); + + Path addHashRewrite(const Path& path); + + void repairClosure(); + + void amDone(ExitCode result) override { Goal::amDone(result); } + + void done(BuildResult::Status status, const std::string& msg = ""); + + PathSet exportReferences(const PathSet& storePaths); +}; + +const Path DerivationGoal::homeDir = "/homeless-shelter"; + +DerivationGoal::DerivationGoal(Worker& worker, const Path& drvPath, + StringSet wantedOutputs, BuildMode buildMode) + : Goal(worker), + useDerivation(true), + drvPath(drvPath), + wantedOutputs(std::move(wantedOutputs)), + buildMode(buildMode) { + state = &DerivationGoal::getDerivation; + name = (format("building of '%1%'") % drvPath).str(); + trace("created"); + + mcExpectedBuilds = + std::make_unique<MaintainCount<uint64_t>>(worker.expectedBuilds); +} + +DerivationGoal::DerivationGoal(Worker& worker, const Path& drvPath, + const BasicDerivation& drv, BuildMode buildMode) + : Goal(worker), + useDerivation(false), + drvPath(drvPath), + buildMode(buildMode) { + this->drv = std::make_unique<BasicDerivation>(drv); + state = &DerivationGoal::haveDerivation; + name = (format("building of %1%") % showPaths(drv.outputPaths())).str(); + trace("created"); + + mcExpectedBuilds = + std::make_unique<MaintainCount<uint64_t>>(worker.expectedBuilds); + + /* Prevent the .chroot directory from being + garbage-collected. (See isActiveTempFile() in gc.cc.) */ + worker.store.addTempRoot(drvPath); +} + +DerivationGoal::~DerivationGoal() { + /* Careful: we should never ever throw an exception from a + destructor. */ + try { + killChild(); + } catch (...) { + ignoreException(); + } + try { + deleteTmpDir(false); + } catch (...) { + ignoreException(); + } + try { + closeLogFile(); + } catch (...) { + ignoreException(); + } +} + +inline bool DerivationGoal::needsHashRewrite() { return !useChroot; } + +void DerivationGoal::killChild() { + if (pid != Pid(-1)) { + worker.childTerminated(this); + + if (buildUser) { + /* If we're using a build user, then there is a tricky + race condition: if we kill the build user before the + child has done its setuid() to the build user uid, then + it won't be killed, and we'll potentially lock up in + pid.wait(). So also send a conventional kill to the + child. */ + ::kill(-static_cast<pid_t>(pid), SIGKILL); /* ignore the result */ + buildUser->kill(); + pid.wait(); + } else { + pid.kill(); + } + + assert(pid == Pid(-1)); + } + + hook.reset(); +} + +void DerivationGoal::timedOut() { + killChild(); + done(BuildResult::TimedOut); +} + +void DerivationGoal::work() { (this->*state)(); } + +void DerivationGoal::addWantedOutputs(const StringSet& outputs) { + /* If we already want all outputs, there is nothing to do. */ + if (wantedOutputs.empty()) { + return; + } + + if (outputs.empty()) { + wantedOutputs.clear(); + needRestart = true; + } else { + for (auto& i : outputs) { + if (wantedOutputs.find(i) == wantedOutputs.end()) { + wantedOutputs.insert(i); + needRestart = true; + } + } + } +} + +void DerivationGoal::getDerivation() { + trace("init"); + + /* The first thing to do is to make sure that the derivation + exists. If it doesn't, it may be created through a + substitute. */ + if (buildMode == bmNormal && worker.store.isValidPath(drvPath)) { + loadDerivation(); + return; + } + + addWaitee(worker.makeSubstitutionGoal(drvPath)); + + state = &DerivationGoal::loadDerivation; +} + +void DerivationGoal::loadDerivation() { + trace("loading derivation"); + + if (nrFailed != 0) { + log_sink() << "cannot build missing derivation '" << drvPath << "'" + << std::endl; + done(BuildResult::MiscFailure); + return; + } + + /* `drvPath' should already be a root, but let's be on the safe + side: if the user forgot to make it a root, we wouldn't want + things being garbage collected while we're busy. */ + worker.store.addTempRoot(drvPath); + + assert(worker.store.isValidPath(drvPath)); + + /* Get the derivation. */ + drv = std::unique_ptr<BasicDerivation>( + new Derivation(worker.store.derivationFromPath(drvPath))); + + haveDerivation(); +} + +void DerivationGoal::haveDerivation() { + trace("have derivation"); + + retrySubstitution = false; + + for (auto& i : drv->outputs) { + worker.store.addTempRoot(i.second.path); + } + + /* Check what outputs paths are not already valid. */ + PathSet invalidOutputs = checkPathValidity(false, buildMode == bmRepair); + + /* If they are all valid, then we're done. */ + if (invalidOutputs.empty() && buildMode == bmNormal) { + done(BuildResult::AlreadyValid); + return; + } + + parsedDrv = std::make_unique<ParsedDerivation>(drvPath, *drv); + + /* We are first going to try to create the invalid output paths + through substitutes. If that doesn't work, we'll build + them. */ + if (settings.useSubstitutes && parsedDrv->substitutesAllowed()) { + for (auto& i : invalidOutputs) { + addWaitee(worker.makeSubstitutionGoal( + i, buildMode == bmRepair ? Repair : NoRepair)); + } + } + + if (waitees.empty()) { /* to prevent hang (no wake-up event) */ + outputsSubstituted(); + } else { + state = &DerivationGoal::outputsSubstituted; + } +} + +void DerivationGoal::outputsSubstituted() { + trace("all outputs substituted (maybe)"); + + if (nrFailed > 0 && nrFailed > nrNoSubstituters + nrIncompleteClosure && + !settings.tryFallback) { + done(BuildResult::TransientFailure, + (format("some substitutes for the outputs of derivation '%1%' failed " + "(usually happens due to networking issues); try '--fallback' " + "to build derivation from source ") % + drvPath) + .str()); + return; + } + + /* If the substitutes form an incomplete closure, then we should + build the dependencies of this derivation, but after that, we + can still use the substitutes for this derivation itself. */ + if (nrIncompleteClosure > 0) { + retrySubstitution = true; + } + + nrFailed = nrNoSubstituters = nrIncompleteClosure = 0; + + if (needRestart) { + needRestart = false; + haveDerivation(); + return; + } + + auto nrInvalid = checkPathValidity(false, buildMode == bmRepair).size(); + if (buildMode == bmNormal && nrInvalid == 0) { + done(BuildResult::Substituted); + return; + } + if (buildMode == bmRepair && nrInvalid == 0) { + repairClosure(); + return; + } + if (buildMode == bmCheck && nrInvalid > 0) { + throw Error(format("some outputs of '%1%' are not valid, so checking is " + "not possible") % + drvPath); + } + + /* Otherwise, at least one of the output paths could not be + produced using a substitute. So we have to build instead. */ + + /* Make sure checkPathValidity() from now on checks all + outputs. */ + wantedOutputs = PathSet(); + + /* The inputs must be built before we can build this goal. */ + if (useDerivation) { + for (auto& i : dynamic_cast<Derivation*>(drv.get())->inputDrvs) { + addWaitee(worker.makeDerivationGoal( + i.first, i.second, buildMode == bmRepair ? bmRepair : bmNormal)); + } + } + + for (auto& i : drv->inputSrcs) { + if (worker.store.isValidPath(i)) { + continue; + } + if (!settings.useSubstitutes) { + throw Error(format("dependency '%1%' of '%2%' does not exist, and " + "substitution is disabled") % + i % drvPath); + } + addWaitee(worker.makeSubstitutionGoal(i)); + } + + if (waitees.empty()) { /* to prevent hang (no wake-up event) */ + inputsRealised(); + } else { + state = &DerivationGoal::inputsRealised; + } +} + +void DerivationGoal::repairClosure() { + /* If we're repairing, we now know that our own outputs are valid. + Now check whether the other paths in the outputs closure are + good. If not, then start derivation goals for the derivations + that produced those outputs. */ + + /* Get the output closure. */ + PathSet outputClosure; + for (auto& i : drv->outputs) { + if (!wantOutput(i.first, wantedOutputs)) { + continue; + } + worker.store.computeFSClosure(i.second.path, outputClosure); + } + + /* Filter out our own outputs (which we have already checked). */ + for (auto& i : drv->outputs) { + outputClosure.erase(i.second.path); + } + + /* Get all dependencies of this derivation so that we know which + derivation is responsible for which path in the output + closure. */ + PathSet inputClosure; + if (useDerivation) { + worker.store.computeFSClosure(drvPath, inputClosure); + } + std::map<Path, Path> outputsToDrv; + for (auto& i : inputClosure) { + if (isDerivation(i)) { + Derivation drv = worker.store.derivationFromPath(i); + for (auto& j : drv.outputs) { + outputsToDrv[j.second.path] = i; + } + } + } + + /* Check each path (slow!). */ + PathSet broken; + for (auto& i : outputClosure) { + if (worker.pathContentsGood(i)) { + continue; + } + log_sink() << "found corrupted or missing path '" << i + << "' in the output closure of '" << drvPath << "'" << std::endl; + Path drvPath2 = outputsToDrv[i]; + if (drvPath2.empty()) { + addWaitee(worker.makeSubstitutionGoal(i, Repair)); + } else { + addWaitee(worker.makeDerivationGoal(drvPath2, PathSet(), bmRepair)); + } + } + + if (waitees.empty()) { + done(BuildResult::AlreadyValid); + return; + } + + state = &DerivationGoal::closureRepaired; +} + +void DerivationGoal::closureRepaired() { + trace("closure repaired"); + if (nrFailed > 0) { + throw Error(format("some paths in the output closure of derivation '%1%' " + "could not be repaired") % + drvPath); + } + done(BuildResult::AlreadyValid); +} + +void DerivationGoal::inputsRealised() { + trace("all inputs realised"); + + if (nrFailed != 0) { + if (!useDerivation) { + throw Error(format("some dependencies of '%1%' are missing") % drvPath); + } + log_sink() << "cannot build derivation '" << drvPath << "': " << nrFailed + << " dependencies couldn't be built" << std::endl; + done(BuildResult::DependencyFailed); + return; + } + + if (retrySubstitution) { + haveDerivation(); + return; + } + + /* Gather information necessary for computing the closure and/or + running the build hook. */ + + /* The outputs are referenceable paths. */ + for (auto& i : drv->outputs) { + log_sink() << "building path " << i.second.path << std::endl; + allPaths.insert(i.second.path); + } + + /* Determine the full set of input paths. */ + + /* First, the input derivations. */ + if (useDerivation) { + for (auto& i : dynamic_cast<Derivation*>(drv.get())->inputDrvs) { + /* Add the relevant output closures of the input derivation + `i' as input paths. Only add the closures of output paths + that are specified as inputs. */ + assert(worker.store.isValidPath(i.first)); + Derivation inDrv = worker.store.derivationFromPath(i.first); + for (auto& j : i.second) { + if (inDrv.outputs.find(j) != inDrv.outputs.end()) { + worker.store.computeFSClosure(inDrv.outputs[j].path, inputPaths); + } else { + throw Error(format("derivation '%1%' requires non-existent output " + "'%2%' from input derivation '%3%'") % + drvPath % j % i.first); + } + } + } + } + + /* Second, the input sources. */ + worker.store.computeFSClosure(drv->inputSrcs, inputPaths); + + DLOG(INFO) << "added input paths " << showPaths(inputPaths); + + allPaths.insert(inputPaths.begin(), inputPaths.end()); + + /* Is this a fixed-output derivation? */ + fixedOutput = drv->isFixedOutput(); + + /* Don't repeat fixed-output derivations since they're already + verified by their output hash.*/ + nrRounds = fixedOutput ? 1 : settings.buildRepeat + 1; + + /* Okay, try to build. Note that here we don't wait for a build + slot to become available, since we don't need one if there is a + build hook. */ + state = &DerivationGoal::tryToBuild; + worker.wakeUp(shared_from_this()); + + result = BuildResult(); +} + +void DerivationGoal::tryToBuild() { + trace("trying to build"); + + /* Obtain locks on all output paths. The locks are automatically + released when we exit this function or Nix crashes. If we + can't acquire the lock, then continue; hopefully some other + goal can start a build, and if not, the main loop will sleep a + few seconds and then retry this goal. */ + PathSet lockFiles; + for (auto& outPath : drv->outputPaths()) { + lockFiles.insert(worker.store.toRealPath(outPath)); + } + + if (!outputLocks.lockPaths(lockFiles, "", false)) { + worker.waitForAWhile(shared_from_this()); + return; + } + + /* Now check again whether the outputs are valid. This is because + another process may have started building in parallel. After + it has finished and released the locks, we can (and should) + reuse its results. (Strictly speaking the first check can be + omitted, but that would be less efficient.) Note that since we + now hold the locks on the output paths, no other process can + build this derivation, so no further checks are necessary. */ + validPaths = checkPathValidity(true, buildMode == bmRepair); + if (buildMode != bmCheck && validPaths.size() == drv->outputs.size()) { + DLOG(INFO) << "skipping build of derivation '" << drvPath + << "', someone beat us to it"; + outputLocks.setDeletion(true); + done(BuildResult::AlreadyValid); + return; + } + + missingPaths = drv->outputPaths(); + if (buildMode != bmCheck) { + for (auto& i : validPaths) { + missingPaths.erase(i); + } + } + + /* If any of the outputs already exist but are not valid, delete + them. */ + for (auto& i : drv->outputs) { + Path path = i.second.path; + if (worker.store.isValidPath(path)) { + continue; + } + DLOG(INFO) << "removing invalid path " << path; + deletePath(worker.store.toRealPath(path)); + } + + /* Don't do a remote build if the derivation has the attribute + `preferLocalBuild' set. Also, check and repair modes are only + supported for local builds. */ + bool buildLocally = buildMode != bmNormal || parsedDrv->willBuildLocally(); + + auto started = [&]() { + std::string msg; + if (buildMode == bmRepair) { + msg = absl::StrFormat("repairing outputs of '%s'", drvPath); + } else if (buildMode == bmCheck) { + msg = absl::StrFormat("checking outputs of '%s'", drvPath); + } else if (nrRounds > 1) { + msg = absl::StrFormat("building '%s' (round %d/%d)", drvPath, curRound, + nrRounds); + } else { + msg = absl::StrFormat("building '%s'", drvPath); + } + + if (hook) { + absl::StrAppend(&msg, absl::StrFormat(" on '%s'", machineName)); + } + + log_sink() << msg << std::endl; + mcRunningBuilds = + std::make_unique<MaintainCount<uint64_t>>(worker.runningBuilds); + }; + + /* Is the build hook willing to accept this job? */ + if (!buildLocally) { + switch (tryBuildHook()) { + case rpAccept: + /* Yes, it has started doing so. Wait until we get + EOF from the hook. */ + result.startTime = time(nullptr); // inexact + state = &DerivationGoal::buildDone; + started(); + return; + case rpPostpone: + /* Not now; wait until at least one child finishes or + the wake-up timeout expires. */ + worker.waitForAWhile(shared_from_this()); + outputLocks.unlock(); + return; + case rpDecline: + /* We should do it ourselves. */ + break; + } + } + + /* Make sure that we are allowed to start a build. If this + derivation prefers to be done locally, do it even if + maxBuildJobs is 0. */ + unsigned int curBuilds = worker.getNrLocalBuilds(); + if (curBuilds >= settings.maxBuildJobs && !(buildLocally && curBuilds == 0)) { + worker.waitForBuildSlot(shared_from_this()); + outputLocks.unlock(); + return; + } + + try { + /* Okay, we have to build. */ + startBuilder(); + + } catch (BuildError& e) { + log_sink() << e.msg() << std::endl; + outputLocks.unlock(); + buildUser.reset(); + worker.permanentFailure = true; + done(BuildResult::InputRejected, e.msg()); + return; + } + + /* This state will be reached when we get EOF on the child's + log pipe. */ + state = &DerivationGoal::buildDone; + + started(); +} + +void replaceValidPath(const Path& storePath, const Path& tmpPath) { + /* We can't atomically replace storePath (the original) with + tmpPath (the replacement), so we have to move it out of the + way first. We'd better not be interrupted here, because if + we're repairing (say) Glibc, we end up with a broken system. */ + Path oldPath = + (format("%1%.old-%2%-%3%") % storePath % getpid() % random()).str(); + if (pathExists(storePath)) { + rename(storePath.c_str(), oldPath.c_str()); + } + if (rename(tmpPath.c_str(), storePath.c_str()) == -1) { + throw SysError(format("moving '%1%' to '%2%'") % tmpPath % storePath); + } + deletePath(oldPath); +} + +MakeError(NotDeterministic, BuildError); + +void DerivationGoal::buildDone() { + trace("build done"); + + /* Release the build user at the end of this function. We don't do + it right away because we don't want another build grabbing this + uid and then messing around with our output. */ + Finally releaseBuildUser([&]() { buildUser.reset(); }); + + /* Since we got an EOF on the logger pipe, the builder is presumed + to have terminated. In fact, the builder could also have + simply have closed its end of the pipe, so just to be sure, + kill it. */ + int status = hook ? hook->pid.kill() : pid.kill(); + + DLOG(INFO) << "builder process for '" << drvPath << "' finished"; + + result.timesBuilt++; + result.stopTime = time(nullptr); + + /* So the child is gone now. */ + worker.childTerminated(this); + + /* Close the read side of the logger pipe. */ + if (hook) { + hook->builderOut.readSide = AutoCloseFD(-1); + hook->fromHook.readSide = AutoCloseFD(-1); + } else { + builderOut.readSide = AutoCloseFD(-1); + } + + /* Close the log file. */ + closeLogFile(); + + /* When running under a build user, make sure that all processes + running under that uid are gone. This is to prevent a + malicious user from leaving behind a process that keeps files + open and modifies them after they have been chown'ed to + root. */ + if (buildUser) { + buildUser->kill(); + } + + bool diskFull = false; + + try { + /* Check the exit status. */ + if (!statusOk(status)) { + /* Heuristically check whether the build failure may have + been caused by a disk full condition. We have no way + of knowing whether the build actually got an ENOSPC. + So instead, check if the disk is (nearly) full now. If + so, we don't mark this build as a permanent failure. */ +#if HAVE_STATVFS + unsigned long long required = + 8ULL * 1024 * 1024; // FIXME: make configurable + struct statvfs st; + if (statvfs(worker.store.realStoreDir.c_str(), &st) == 0 && + static_cast<unsigned long long>(st.f_bavail) * st.f_bsize < + required) { + diskFull = true; + } + if (statvfs(tmpDir.c_str(), &st) == 0 && + static_cast<unsigned long long>(st.f_bavail) * st.f_bsize < + required) { + diskFull = true; + } +#endif + + deleteTmpDir(false); + + /* Move paths out of the chroot for easier debugging of + build failures. */ + if (useChroot && buildMode == bmNormal) { + for (auto& i : missingPaths) { + if (pathExists(chrootRootDir + i)) { + rename((chrootRootDir + i).c_str(), i.c_str()); + } + } + } + + std::string msg = + (format("builder for '%1%' %2%") % drvPath % statusToString(status)) + .str(); + + if (!settings.verboseBuild && !logTail.empty()) { + msg += (format("; last %d log lines:") % logTail.size()).str(); + for (auto& line : logTail) { + msg += "\n " + line; + } + } + + if (diskFull) { + msg += + "\nnote: build failure may have been caused by lack of free disk " + "space"; + } + + throw BuildError(msg); + } + + /* Compute the FS closure of the outputs and register them as + being valid. */ + registerOutputs(); + + if (settings.postBuildHook != "") { + log_sink() << "running post-build-hook '" << settings.postBuildHook + << "' [" << drvPath << "]" << std::endl; + auto outputPaths = drv->outputPaths(); + std::map<std::string, std::string> hookEnvironment = getEnv(); + + hookEnvironment.emplace("DRV_PATH", drvPath); + hookEnvironment.emplace("OUT_PATHS", + absl::StripTrailingAsciiWhitespace( + concatStringsSep(" ", outputPaths))); + + RunOptions opts(settings.postBuildHook, {}); + opts.environment = hookEnvironment; + + struct LogSink : Sink { + std::string currentLine; + + void operator()(const unsigned char* data, size_t len) override { + for (size_t i = 0; i < len; i++) { + auto c = data[i]; + + if (c == '\n') { + flushLine(); + } else { + currentLine += c; + } + } + } + + void flushLine() { + if (settings.verboseBuild) { + LOG(ERROR) << "post-build-hook: " << currentLine; + } + currentLine.clear(); + } + + ~LogSink() override { + if (!currentLine.empty()) { + currentLine += '\n'; + flushLine(); + } + } + }; + LogSink sink; + + opts.standardOut = &sink; + opts.mergeStderrToStdout = true; + runProgram2(opts); + } + + if (buildMode == bmCheck) { + done(BuildResult::Built); + return; + } + + /* Delete unused redirected outputs (when doing hash rewriting). */ + for (auto& i : redirectedOutputs) { + deletePath(i.second); + } + + /* Delete the chroot (if we were using one). */ + autoDelChroot.reset(); /* this runs the destructor */ + + deleteTmpDir(true); + + /* Repeat the build if necessary. */ + if (curRound++ < nrRounds) { + outputLocks.unlock(); + state = &DerivationGoal::tryToBuild; + worker.wakeUp(shared_from_this()); + return; + } + + /* It is now safe to delete the lock files, since all future + lockers will see that the output paths are valid; they will + not create new lock files with the same names as the old + (unlinked) lock files. */ + outputLocks.setDeletion(true); + outputLocks.unlock(); + + } catch (BuildError& e) { + log_sink() << e.msg() << std::endl; + + outputLocks.unlock(); + + BuildResult::Status st = BuildResult::MiscFailure; + + if (hook && WIFEXITED(status) && WEXITSTATUS(status) == 101) { + st = BuildResult::TimedOut; + + } else if (hook && (!WIFEXITED(status) || WEXITSTATUS(status) != 100)) { + } + + else { + st = dynamic_cast<NotDeterministic*>(&e) != nullptr + ? BuildResult::NotDeterministic + : statusOk(status) ? BuildResult::OutputRejected + : fixedOutput || diskFull ? BuildResult::TransientFailure + : BuildResult::PermanentFailure; + } + + done(st, e.msg()); + return; + } + + done(BuildResult::Built); +} + +HookReply DerivationGoal::tryBuildHook() { + if (!worker.tryBuildHook || !useDerivation) { + return rpDecline; + } + + if (!worker.hook) { + worker.hook = std::make_unique<HookInstance>(); + } + + try { + /* Send the request to the hook. */ + worker.hook->sink << "try" + << (worker.getNrLocalBuilds() < settings.maxBuildJobs ? 1 + : 0) + << drv->platform << drvPath + << parsedDrv->getRequiredSystemFeatures(); + worker.hook->sink.flush(); + + /* Read the first line of input, which should be a word indicating + whether the hook wishes to perform the build. */ + std::string reply; + while (true) { + std::string s = readLine(worker.hook->fromHook.readSide.get()); + if (std::string(s, 0, 2) == "# ") { + reply = std::string(s, 2); + break; + } + s += "\n"; + std::cerr << s; + } + + DLOG(INFO) << "hook reply is " << reply; + + if (reply == "decline") { + return rpDecline; + } + if (reply == "decline-permanently") { + worker.tryBuildHook = false; + worker.hook = nullptr; + return rpDecline; + } else if (reply == "postpone") { + return rpPostpone; + } else if (reply != "accept") { + throw Error(format("bad hook reply '%1%'") % reply); + } + } catch (SysError& e) { + if (e.errNo == EPIPE) { + log_sink() << "build hook died unexpectedly: " + << absl::StripTrailingAsciiWhitespace( + drainFD(worker.hook->fromHook.readSide.get())) + << std::endl; + worker.hook = nullptr; + return rpDecline; + } + throw; + } + + hook = std::move(worker.hook); + + machineName = readLine(hook->fromHook.readSide.get()); + + /* Tell the hook all the inputs that have to be copied to the + remote system. */ + hook->sink << inputPaths; + + /* Tell the hooks the missing outputs that have to be copied back + from the remote system. */ + hook->sink << missingPaths; + + hook->sink = FdSink(); + hook->toHook.writeSide = AutoCloseFD(-1); + + /* Create the log file and pipe. */ + Path logFile = openLogFile(); + + std::set<int> fds; + fds.insert(hook->fromHook.readSide.get()); + fds.insert(hook->builderOut.readSide.get()); + worker.childStarted(shared_from_this(), fds, false, false); + + return rpAccept; +} + +void chmod_(const Path& path, mode_t mode) { + if (chmod(path.c_str(), mode) == -1) { + throw SysError(format("setting permissions on '%1%'") % path); + } +} + +int childEntry(void* arg) { + (static_cast<DerivationGoal*>(arg))->runChild(); + return 1; +} + +PathSet DerivationGoal::exportReferences(const PathSet& storePaths) { + PathSet paths; + + for (auto storePath : storePaths) { + /* Check that the store path is valid. */ + if (!worker.store.isInStore(storePath)) { + throw BuildError( + format("'exportReferencesGraph' contains a non-store path '%1%'") % + storePath); + } + + storePath = worker.store.toStorePath(storePath); + + if (inputPaths.count(storePath) == 0u) { + throw BuildError( + "cannot export references of path '%s' because it is not in the " + "input closure of the derivation", + storePath); + } + + worker.store.computeFSClosure(storePath, paths); + } + + /* If there are derivations in the graph, then include their + outputs as well. This is useful if you want to do things + like passing all build-time dependencies of some path to a + derivation that builds a NixOS DVD image. */ + PathSet paths2(paths); + + for (auto& j : paths2) { + if (isDerivation(j)) { + Derivation drv = worker.store.derivationFromPath(j); + for (auto& k : drv.outputs) { + worker.store.computeFSClosure(k.second.path, paths); + } + } + } + + return paths; +} + +static std::once_flag dns_resolve_flag; + +static void preloadNSS() { + /* builtin:fetchurl can trigger a DNS lookup, which with glibc can trigger a + dynamic library load of one of the glibc NSS libraries in a sandboxed + child, which will fail unless the library's already been loaded in the + parent. So we force a lookup of an invalid domain to force the NSS + machinery to + load its lookup libraries in the parent before any child gets a chance to. + */ + std::call_once(dns_resolve_flag, []() { + struct addrinfo* res = nullptr; + + if (getaddrinfo("this.pre-initializes.the.dns.resolvers.invalid.", "http", + nullptr, &res) != 0) { + if (res != nullptr) { + freeaddrinfo(res); + } + } + }); +} + +void DerivationGoal::startBuilder() { + /* Right platform? */ + if (!parsedDrv->canBuildLocally()) { + throw Error( + "a '%s' with features {%s} is required to build '%s', but I am a '%s' " + "with features {%s}", + drv->platform, + concatStringsSep(", ", parsedDrv->getRequiredSystemFeatures()), drvPath, + settings.thisSystem, concatStringsSep(", ", settings.systemFeatures)); + } + + if (drv->isBuiltin()) { + preloadNSS(); + } + + /* Are we doing a chroot build? */ + { + auto noChroot = parsedDrv->getBoolAttr("__noChroot"); + if (settings.sandboxMode == smEnabled) { + if (noChroot) { + throw Error(format("derivation '%1%' has '__noChroot' set, " + "but that's not allowed when 'sandbox' is 'true'") % + drvPath); + } + useChroot = true; + } else if (settings.sandboxMode == smDisabled) { + useChroot = false; + } else if (settings.sandboxMode == smRelaxed) { + useChroot = !fixedOutput && !noChroot; + } + } + + if (worker.store.storeDir != worker.store.realStoreDir) { + useChroot = true; + } + + /* If `build-users-group' is not empty, then we have to build as + one of the members of that group. */ + if (settings.buildUsersGroup != "" && getuid() == 0) { + buildUser = std::make_unique<UserLock>(); + + /* Make sure that no other processes are executing under this + uid. */ + buildUser->kill(); + } + + /* Create a temporary directory where the build will take + place. */ + auto drvName = storePathToName(drvPath); + tmpDir = createTempDir("", "nix-build-" + drvName, false, false, 0700); + + chownToBuilder(tmpDir); + + /* Substitute output placeholders with the actual output paths. */ + for (auto& output : drv->outputs) { + inputRewrites[hashPlaceholder(output.first)] = output.second.path; + } + + /* Construct the environment passed to the builder. */ + initEnv(); + + writeStructuredAttrs(); + + /* Handle exportReferencesGraph(), if set. */ + if (!parsedDrv->getStructuredAttrs()) { + /* The `exportReferencesGraph' feature allows the references graph + to be passed to a builder. This attribute should be a list of + pairs [name1 path1 name2 path2 ...]. The references graph of + each `pathN' will be stored in a text file `nameN' in the + temporary build directory. The text files have the format used + by `nix-store --register-validity'. However, the deriver + fields are left empty. */ + std::string s = get(drv->env, "exportReferencesGraph"); + std::vector<std::string> ss = + absl::StrSplit(s, absl::ByAnyChar(" \t\n\r"), absl::SkipEmpty()); + if (ss.size() % 2 != 0) { + throw BuildError(absl::StrFormat( + "odd number of tokens %d in 'exportReferencesGraph': '%s'", ss.size(), + s)); + } + for (auto i = ss.begin(); i != ss.end();) { + std::string fileName = *i++; + checkStoreName(fileName); /* !!! abuse of this function */ + Path storePath = *i++; + + /* Write closure info to <fileName>. */ + writeFile(tmpDir + "/" + fileName, + worker.store.makeValidityRegistration( + exportReferences({storePath}), false, false)); + } + } + + if (useChroot) { + /* Allow a user-configurable set of directories from the + host file system. */ + PathSet dirs = settings.sandboxPaths; + PathSet dirs2 = settings.extraSandboxPaths; + dirs.insert(dirs2.begin(), dirs2.end()); + + dirsInChroot.clear(); + + for (auto i : dirs) { + if (i.empty()) { + continue; + } + bool optional = false; + if (i[i.size() - 1] == '?') { + optional = true; + i.pop_back(); + } + size_t p = i.find('='); + if (p == std::string::npos) { + dirsInChroot[i] = ChrootPath(i, optional); + } else { + dirsInChroot[std::string(i, 0, p)] = + ChrootPath(std::string(i, p + 1), optional); + } + } + dirsInChroot[tmpDirInSandbox] = ChrootPath(tmpDir); + + /* Add the closure of store paths to the chroot. */ + PathSet closure; + for (auto& i : dirsInChroot) { + try { + if (worker.store.isInStore(i.second.source)) { + worker.store.computeFSClosure( + worker.store.toStorePath(i.second.source), closure); + } + } catch (InvalidPath& e) { + } catch (Error& e) { + throw Error(format("while processing 'sandbox-paths': %s") % e.what()); + } + } + for (auto& i : closure) { + dirsInChroot[i] = ChrootPath(i); + } + + PathSet allowedPaths = settings.allowedImpureHostPrefixes; + + /* This works like the above, except on a per-derivation level */ + auto impurePaths = + parsedDrv->getStringsAttr("__impureHostDeps").value_or(Strings()); + + for (auto& i : impurePaths) { + bool found = false; + /* Note: we're not resolving symlinks here to prevent + giving a non-root user info about inaccessible + files. */ + Path canonI = canonPath(i); + /* If only we had a trie to do this more efficiently :) luckily, these are + * generally going to be pretty small */ + for (auto& a : allowedPaths) { + Path canonA = canonPath(a); + if (canonI == canonA || isInDir(canonI, canonA)) { + found = true; + break; + } + } + if (!found) { + throw Error(format("derivation '%1%' requested impure path '%2%', but " + "it was not in allowed-impure-host-deps") % + drvPath % i); + } + + dirsInChroot[i] = ChrootPath(i); + } + + /* Create a temporary directory in which we set up the chroot + environment using bind-mounts. We put it in the Nix store + to ensure that we can create hard-links to non-directory + inputs in the fake Nix store in the chroot (see below). */ + chrootRootDir = worker.store.toRealPath(drvPath) + ".chroot"; + deletePath(chrootRootDir); + + /* Clean up the chroot directory automatically. */ + autoDelChroot = std::make_shared<AutoDelete>(chrootRootDir); + + DLOG(INFO) << "setting up chroot environment in '" << chrootRootDir << "'"; + + if (mkdir(chrootRootDir.c_str(), 0750) == -1) { + throw SysError(format("cannot create '%1%'") % chrootRootDir); + } + + if (buildUser && + chown(chrootRootDir.c_str(), 0, buildUser->getGID()) == -1) { + throw SysError(format("cannot change ownership of '%1%'") % + chrootRootDir); + } + + /* Create a writable /tmp in the chroot. Many builders need + this. (Of course they should really respect $TMPDIR + instead.) */ + Path chrootTmpDir = chrootRootDir + "/tmp"; + createDirs(chrootTmpDir); + chmod_(chrootTmpDir, 01777); + + /* Create a /etc/passwd with entries for the build user and the + nobody account. The latter is kind of a hack to support + Samba-in-QEMU. */ + createDirs(chrootRootDir + "/etc"); + + writeFile(chrootRootDir + "/etc/passwd", + fmt("root:x:0:0:Nix build user:%3%:/noshell\n" + "nixbld:x:%1%:%2%:Nix build user:%3%:/noshell\n" + "nobody:x:65534:65534:Nobody:/:/noshell\n", + sandboxUid, sandboxGid, settings.sandboxBuildDir)); + + /* Declare the build user's group so that programs get a consistent + view of the system (e.g., "id -gn"). */ + writeFile(chrootRootDir + "/etc/group", (format("root:x:0:\n" + "nixbld:!:%1%:\n" + "nogroup:x:65534:\n") % + sandboxGid) + .str()); + + /* Create /etc/hosts with localhost entry. */ + if (!fixedOutput) { + writeFile(chrootRootDir + "/etc/hosts", + "127.0.0.1 localhost\n::1 localhost\n"); + } + + /* Make the closure of the inputs available in the chroot, + rather than the whole Nix store. This prevents any access + to undeclared dependencies. Directories are bind-mounted, + while other inputs are hard-linked (since only directories + can be bind-mounted). !!! As an extra security + precaution, make the fake Nix store only writable by the + build user. */ + Path chrootStoreDir = chrootRootDir + worker.store.storeDir; + createDirs(chrootStoreDir); + chmod_(chrootStoreDir, 01775); + + if (buildUser && + chown(chrootStoreDir.c_str(), 0, buildUser->getGID()) == -1) { + throw SysError(format("cannot change ownership of '%1%'") % + chrootStoreDir); + } + + for (auto& i : inputPaths) { + Path r = worker.store.toRealPath(i); + struct stat st; + if (lstat(r.c_str(), &st) != 0) { + throw SysError(format("getting attributes of path '%1%'") % i); + } + if (S_ISDIR(st.st_mode)) { + dirsInChroot[i] = ChrootPath(r); + } else { + Path p = chrootRootDir + i; + DLOG(INFO) << "linking '" << p << "' to '" << r << "'"; + if (link(r.c_str(), p.c_str()) == -1) { + /* Hard-linking fails if we exceed the maximum + link count on a file (e.g. 32000 of ext3), + which is quite possible after a `nix-store + --optimise'. */ + if (errno != EMLINK) { + throw SysError(format("linking '%1%' to '%2%'") % p % i); + } + StringSink sink; + dumpPath(r, sink); + StringSource source(*sink.s); + restorePath(p, source); + } + } + } + + /* If we're repairing, checking or rebuilding part of a + multiple-outputs derivation, it's possible that we're + rebuilding a path that is in settings.dirsInChroot + (typically the dependencies of /bin/sh). Throw them + out. */ + for (auto& i : drv->outputs) { + dirsInChroot.erase(i.second.path); + } + } + + if (needsHashRewrite()) { + if (pathExists(homeDir)) { + throw Error(format("directory '%1%' exists; please remove it") % homeDir); + } + + /* We're not doing a chroot build, but we have some valid + output paths. Since we can't just overwrite or delete + them, we have to do hash rewriting: i.e. in the + environment/arguments passed to the build, we replace the + hashes of the valid outputs with unique dummy strings; + after the build, we discard the redirected outputs + corresponding to the valid outputs, and rewrite the + contents of the new outputs to replace the dummy strings + with the actual hashes. */ + if (!validPaths.empty()) { + for (auto& i : validPaths) { + addHashRewrite(i); + } + } + + /* If we're repairing, then we don't want to delete the + corrupt outputs in advance. So rewrite them as well. */ + if (buildMode == bmRepair) { + for (auto& i : missingPaths) { + if (worker.store.isValidPath(i) && pathExists(i)) { + addHashRewrite(i); + redirectedBadOutputs.insert(i); + } + } + } + } + + if (useChroot && settings.preBuildHook != "" && + (dynamic_cast<Derivation*>(drv.get()) != nullptr)) { + DLOG(INFO) << "executing pre-build hook '" << settings.preBuildHook << "'"; + auto args = + useChroot ? Strings({drvPath, chrootRootDir}) : Strings({drvPath}); + enum BuildHookState { stBegin, stExtraChrootDirs }; + auto state = stBegin; + auto lines = runProgram(settings.preBuildHook, false, args); + auto lastPos = std::string::size_type{0}; + for (auto nlPos = lines.find('\n'); nlPos != std::string::npos; + nlPos = lines.find('\n', lastPos)) { + auto line = std::string{lines, lastPos, nlPos - lastPos}; + lastPos = nlPos + 1; + if (state == stBegin) { + if (line == "extra-sandbox-paths" || line == "extra-chroot-dirs") { + state = stExtraChrootDirs; + } else { + throw Error(format("unknown pre-build hook command '%1%'") % line); + } + } else if (state == stExtraChrootDirs) { + if (line.empty()) { + state = stBegin; + } else { + auto p = line.find('='); + if (p == std::string::npos) { + dirsInChroot[line] = ChrootPath(line); + } else { + dirsInChroot[std::string(line, 0, p)] = + ChrootPath(std::string(line, p + 1)); + } + } + } + } + } + + /* Run the builder. */ + DLOG(INFO) << "executing builder '" << drv->builder << "'"; + + /* Create the log file. */ + Path logFile = openLogFile(); + + /* Create a pipe to get the output of the builder. */ + // builderOut.create(); + + builderOut.readSide = AutoCloseFD(posix_openpt(O_RDWR | O_NOCTTY)); + if (!builderOut.readSide) { + throw SysError("opening pseudoterminal master"); + } + + std::string slaveName(ptsname(builderOut.readSide.get())); + + if (buildUser) { + if (chmod(slaveName.c_str(), 0600) != 0) { + throw SysError("changing mode of pseudoterminal slave"); + } + + if (chown(slaveName.c_str(), buildUser->getUID(), 0) != 0) { + throw SysError("changing owner of pseudoterminal slave"); + } + } else { + if (grantpt(builderOut.readSide.get()) != 0) { + throw SysError("granting access to pseudoterminal slave"); + } + } + +#if 0 + // Mount the pt in the sandbox so that the "tty" command works. + // FIXME: this doesn't work with the new devpts in the sandbox. + if (useChroot) + dirsInChroot[slaveName] = {slaveName, false}; +#endif + + if (unlockpt(builderOut.readSide.get()) != 0) { + throw SysError("unlocking pseudoterminal"); + } + + builderOut.writeSide = + AutoCloseFD(open(slaveName.c_str(), O_RDWR | O_NOCTTY)); + if (!builderOut.writeSide) { + throw SysError("opening pseudoterminal slave"); + } + + // Put the pt into raw mode to prevent \n -> \r\n translation. + struct termios term; + if (tcgetattr(builderOut.writeSide.get(), &term) != 0) { + throw SysError("getting pseudoterminal attributes"); + } + + cfmakeraw(&term); + + if (tcsetattr(builderOut.writeSide.get(), TCSANOW, &term) != 0) { + throw SysError("putting pseudoterminal into raw mode"); + } + + result.startTime = time(nullptr); + + /* Fork a child to build the package. */ + ProcessOptions options; + +#if __linux__ + if (useChroot) { + /* Set up private namespaces for the build: + + - The PID namespace causes the build to start as PID 1. + Processes outside of the chroot are not visible to those + on the inside, but processes inside the chroot are + visible from the outside (though with different PIDs). + + - The private mount namespace ensures that all the bind + mounts we do will only show up in this process and its + children, and will disappear automatically when we're + done. + + - The private network namespace ensures that the builder + cannot talk to the outside world (or vice versa). It + only has a private loopback interface. (Fixed-output + derivations are not run in a private network namespace + to allow functions like fetchurl to work.) + + - The IPC namespace prevents the builder from communicating + with outside processes using SysV IPC mechanisms (shared + memory, message queues, semaphores). It also ensures + that all IPC objects are destroyed when the builder + exits. + + - The UTS namespace ensures that builders see a hostname of + localhost rather than the actual hostname. + + We use a helper process to do the clone() to work around + clone() being broken in multi-threaded programs due to + at-fork handlers not being run. Note that we use + CLONE_PARENT to ensure that the real builder is parented to + us. + */ + + if (!fixedOutput) { + privateNetwork = true; + } + + userNamespaceSync.create(); + + Pid helper(startProcess( + [&]() { + /* Drop additional groups here because we can't do it + after we've created the new user namespace. FIXME: + this means that if we're not root in the parent + namespace, we can't drop additional groups; they will + be mapped to nogroup in the child namespace. There does + not seem to be a workaround for this. (But who can tell + from reading user_namespaces(7)?) + See also https://lwn.net/Articles/621612/. */ + if (getuid() == 0 && setgroups(0, nullptr) == -1) { + throw SysError("setgroups failed"); + } + + size_t stackSize = 1 * 1024 * 1024; + char* stack = static_cast<char*>( + mmap(nullptr, stackSize, PROT_WRITE | PROT_READ, + MAP_PRIVATE | MAP_ANONYMOUS | MAP_STACK, -1, 0)); + if (stack == MAP_FAILED) { + throw SysError("allocating stack"); + } + + int flags = CLONE_NEWUSER | CLONE_NEWPID | CLONE_NEWNS | + CLONE_NEWIPC | CLONE_NEWUTS | CLONE_PARENT | SIGCHLD; + if (privateNetwork) { + flags |= CLONE_NEWNET; + } + + pid_t child = clone(childEntry, stack + stackSize, flags, this); + if (child == -1 && errno == EINVAL) { + /* Fallback for Linux < 2.13 where CLONE_NEWPID and + CLONE_PARENT are not allowed together. */ + flags &= ~CLONE_NEWPID; + child = clone(childEntry, stack + stackSize, flags, this); + } + if (child == -1 && (errno == EPERM || errno == EINVAL)) { + /* Some distros patch Linux to not allow unpriveleged + * user namespaces. If we get EPERM or EINVAL, try + * without CLONE_NEWUSER and see if that works. + */ + flags &= ~CLONE_NEWUSER; + child = clone(childEntry, stack + stackSize, flags, this); + } + /* Otherwise exit with EPERM so we can handle this in the + parent. This is only done when sandbox-fallback is set + to true (the default). */ + if (child == -1 && (errno == EPERM || errno == EINVAL) && + settings.sandboxFallback) { + _exit(1); + } + if (child == -1) { + throw SysError("cloning builder process"); + } + + writeFull(builderOut.writeSide.get(), std::to_string(child) + "\n"); + _exit(0); + }, + options)); + + int res = helper.wait(); + if (res != 0 && settings.sandboxFallback) { + useChroot = false; + initTmpDir(); + goto fallback; + } else if (res != 0) { + throw Error("unable to start build process"); + } + + userNamespaceSync.readSide = AutoCloseFD(-1); + + pid_t tmp; + if (!absl::SimpleAtoi(readLine(builderOut.readSide.get()), &tmp)) { + abort(); + } + pid = tmp; + + /* Set the UID/GID mapping of the builder's user namespace + such that the sandbox user maps to the build user, or to + the calling user (if build users are disabled). */ + uid_t hostUid = buildUser ? buildUser->getUID() : getuid(); + uid_t hostGid = buildUser ? buildUser->getGID() : getgid(); + + writeFile("/proc/" + std::to_string(static_cast<pid_t>(pid)) + "/uid_map", + (format("%d %d 1") % sandboxUid % hostUid).str()); + + writeFile("/proc/" + std::to_string(static_cast<pid_t>(pid)) + "/setgroups", + "deny"); + + writeFile("/proc/" + std::to_string(static_cast<pid_t>(pid)) + "/gid_map", + (format("%d %d 1") % sandboxGid % hostGid).str()); + + /* Signal the builder that we've updated its user + namespace. */ + writeFull(userNamespaceSync.writeSide.get(), "1"); + userNamespaceSync.writeSide = AutoCloseFD(-1); + + } else +#endif + { + fallback: + pid = startProcess([&]() { runChild(); }, options); + } + + /* parent */ + pid.setSeparatePG(true); + builderOut.writeSide = AutoCloseFD(-1); + worker.childStarted(shared_from_this(), {builderOut.readSide.get()}, true, + true); + + /* Check if setting up the build environment failed. */ + while (true) { + std::string msg = readLine(builderOut.readSide.get()); + if (std::string(msg, 0, 1) == "\1") { + if (msg.size() == 1) { + break; + } + throw Error(std::string(msg, 1)); + } + DLOG(INFO) << msg; + } +} + +void DerivationGoal::initTmpDir() { + /* In a sandbox, for determinism, always use the same temporary + directory. */ +#if __linux__ + tmpDirInSandbox = useChroot ? settings.sandboxBuildDir : tmpDir; +#else + tmpDirInSandbox = tmpDir; +#endif + + /* In non-structured mode, add all bindings specified in the + derivation via the environment, except those listed in the + passAsFile attribute. Those are passed as file names pointing + to temporary files containing the contents. Note that + passAsFile is ignored in structure mode because it's not + needed (attributes are not passed through the environment, so + there is no size constraint). */ + if (!parsedDrv->getStructuredAttrs()) { + std::set<std::string> passAsFile = + absl::StrSplit(get(drv->env, "passAsFile"), absl::ByAnyChar(" \t\n\r"), + absl::SkipEmpty()); + for (auto& i : drv->env) { + if (passAsFile.find(i.first) == passAsFile.end()) { + env[i.first] = i.second; + } else { + auto hash = hashString(htSHA256, i.first); + std::string fn = ".attr-" + hash.to_string(Base32, false); + Path p = tmpDir + "/" + fn; + writeFile(p, rewriteStrings(i.second, inputRewrites)); + chownToBuilder(p); + env[i.first + "Path"] = tmpDirInSandbox + "/" + fn; + } + } + } + + /* For convenience, set an environment pointing to the top build + directory. */ + env["NIX_BUILD_TOP"] = tmpDirInSandbox; + + /* Also set TMPDIR and variants to point to this directory. */ + env["TMPDIR"] = env["TEMPDIR"] = env["TMP"] = env["TEMP"] = tmpDirInSandbox; + + /* Explicitly set PWD to prevent problems with chroot builds. In + particular, dietlibc cannot figure out the cwd because the + inode of the current directory doesn't appear in .. (because + getdents returns the inode of the mount point). */ + env["PWD"] = tmpDirInSandbox; +} + +void DerivationGoal::initEnv() { + env.clear(); + + /* Most shells initialise PATH to some default (/bin:/usr/bin:...) when + PATH is not set. We don't want this, so we fill it in with some dummy + value. */ + env["PATH"] = "/path-not-set"; + + /* Set HOME to a non-existing path to prevent certain programs from using + /etc/passwd (or NIS, or whatever) to locate the home directory (for + example, wget looks for ~/.wgetrc). I.e., these tools use /etc/passwd + if HOME is not set, but they will just assume that the settings file + they are looking for does not exist if HOME is set but points to some + non-existing path. */ + env["HOME"] = homeDir; + + /* Tell the builder where the Nix store is. Usually they + shouldn't care, but this is useful for purity checking (e.g., + the compiler or linker might only want to accept paths to files + in the store or in the build directory). */ + env["NIX_STORE"] = worker.store.storeDir; + + /* The maximum number of cores to utilize for parallel building. */ + env["NIX_BUILD_CORES"] = (format("%d") % settings.buildCores).str(); + + initTmpDir(); + + /* Compatibility hack with Nix <= 0.7: if this is a fixed-output + derivation, tell the builder, so that for instance `fetchurl' + can skip checking the output. On older Nixes, this environment + variable won't be set, so `fetchurl' will do the check. */ + if (fixedOutput) { + env["NIX_OUTPUT_CHECKED"] = "1"; + } + + /* *Only* if this is a fixed-output derivation, propagate the + values of the environment variables specified in the + `impureEnvVars' attribute to the builder. This allows for + instance environment variables for proxy configuration such as + `http_proxy' to be easily passed to downloaders like + `fetchurl'. Passing such environment variables from the caller + to the builder is generally impure, but the output of + fixed-output derivations is by definition pure (since we + already know the cryptographic hash of the output). */ + if (fixedOutput) { + for (auto& i : + parsedDrv->getStringsAttr("impureEnvVars").value_or(Strings())) { + env[i] = getEnv(i).value_or(""); + } + } + + /* Currently structured log messages piggyback on stderr, but we + may change that in the future. So tell the builder which file + descriptor to use for that. */ + env["NIX_LOG_FD"] = "2"; + + /* Trigger colored output in various tools. */ + env["TERM"] = "xterm-256color"; +} + +static std::regex shVarName("[A-Za-z_][A-Za-z0-9_]*"); + +void DerivationGoal::writeStructuredAttrs() { + auto& structuredAttrs = parsedDrv->getStructuredAttrs(); + if (!structuredAttrs) { + return; + } + + auto json = *structuredAttrs; + + /* Add an "outputs" object containing the output paths. */ + nlohmann::json outputs; + for (auto& i : drv->outputs) { + outputs[i.first] = rewriteStrings(i.second.path, inputRewrites); + } + json["outputs"] = outputs; + + /* Handle exportReferencesGraph. */ + auto e = json.find("exportReferencesGraph"); + if (e != json.end() && e->is_object()) { + for (auto i = e->begin(); i != e->end(); ++i) { + std::ostringstream str; + { + JSONPlaceholder jsonRoot(str, true); + PathSet storePaths; + for (auto& p : *i) { + storePaths.insert(p.get<std::string>()); + } + worker.store.pathInfoToJSON(jsonRoot, exportReferences(storePaths), + false, true); + } + json[i.key()] = nlohmann::json::parse(str.str()); // urgh + } + } + + writeFile(tmpDir + "/.attrs.json", + rewriteStrings(json.dump(), inputRewrites)); + chownToBuilder(tmpDir + "/.attrs.json"); + + /* As a convenience to bash scripts, write a shell file that + maps all attributes that are representable in bash - + namely, strings, integers, nulls, Booleans, and arrays and + objects consisting entirely of those values. (So nested + arrays or objects are not supported.) */ + + auto handleSimpleType = + [](const nlohmann::json& value) -> std::optional<std::string> { + if (value.is_string()) { + return shellEscape(value); + } + + if (value.is_number()) { + auto f = value.get<float>(); + if (std::ceil(f) == f) { + return std::to_string(value.get<int>()); + } + } + + if (value.is_null()) { + return std::string("''"); + } + + if (value.is_boolean()) { + return value.get<bool>() ? std::string("1") : std::string(""); + } + + return {}; + }; + + std::string jsonSh; + + for (auto i = json.begin(); i != json.end(); ++i) { + if (!std::regex_match(i.key(), shVarName)) { + continue; + } + + auto& value = i.value(); + + auto s = handleSimpleType(value); + if (s) { + jsonSh += fmt("declare %s=%s\n", i.key(), *s); + + } else if (value.is_array()) { + std::string s2; + bool good = true; + + for (auto i = value.begin(); i != value.end(); ++i) { + auto s3 = handleSimpleType(i.value()); + if (!s3) { + good = false; + break; + } + s2 += *s3; + s2 += ' '; + } + + if (good) { + jsonSh += fmt("declare -a %s=(%s)\n", i.key(), s2); + } + } + + else if (value.is_object()) { + std::string s2; + bool good = true; + + for (auto i = value.begin(); i != value.end(); ++i) { + auto s3 = handleSimpleType(i.value()); + if (!s3) { + good = false; + break; + } + s2 += fmt("[%s]=%s ", shellEscape(i.key()), *s3); + } + + if (good) { + jsonSh += fmt("declare -A %s=(%s)\n", i.key(), s2); + } + } + } + + writeFile(tmpDir + "/.attrs.sh", rewriteStrings(jsonSh, inputRewrites)); + chownToBuilder(tmpDir + "/.attrs.sh"); +} + +void DerivationGoal::chownToBuilder(const Path& path) { + if (!buildUser) { + return; + } + if (chown(path.c_str(), buildUser->getUID(), buildUser->getGID()) == -1) { + throw SysError(format("cannot change ownership of '%1%'") % path); + } +} + +void setupSeccomp() { +#if __linux__ + if (!settings.filterSyscalls) { + return; + } +#if HAVE_SECCOMP + scmp_filter_ctx ctx; + + if ((ctx = seccomp_init(SCMP_ACT_ALLOW)) == nullptr) { + throw SysError("unable to initialize seccomp mode 2"); + } + + Finally cleanup([&]() { seccomp_release(ctx); }); + + if (nativeSystem == "x86_64-linux" && + seccomp_arch_add(ctx, SCMP_ARCH_X86) != 0) { + throw SysError("unable to add 32-bit seccomp architecture"); + } + + if (nativeSystem == "x86_64-linux" && + seccomp_arch_add(ctx, SCMP_ARCH_X32) != 0) { + throw SysError("unable to add X32 seccomp architecture"); + } + + if (nativeSystem == "aarch64-linux" && + seccomp_arch_add(ctx, SCMP_ARCH_ARM) != 0) { + LOG(ERROR) << "unable to add ARM seccomp architecture; this may result in " + << "spurious build failures if running 32-bit ARM processes"; + } + + /* Prevent builders from creating setuid/setgid binaries. */ + for (int perm : {S_ISUID, S_ISGID}) { + if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EPERM), SCMP_SYS(chmod), 1, + SCMP_A1(SCMP_CMP_MASKED_EQ, (scmp_datum_t)perm, + (scmp_datum_t)perm)) != 0) { + throw SysError("unable to add seccomp rule"); + } + + if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EPERM), SCMP_SYS(fchmod), 1, + SCMP_A1(SCMP_CMP_MASKED_EQ, (scmp_datum_t)perm, + (scmp_datum_t)perm)) != 0) { + throw SysError("unable to add seccomp rule"); + } + + if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(EPERM), SCMP_SYS(fchmodat), 1, + SCMP_A2(SCMP_CMP_MASKED_EQ, (scmp_datum_t)perm, + (scmp_datum_t)perm)) != 0) { + throw SysError("unable to add seccomp rule"); + } + } + + /* Prevent builders from creating EAs or ACLs. Not all filesystems + support these, and they're not allowed in the Nix store because + they're not representable in the NAR serialisation. */ + if (seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ENOTSUP), SCMP_SYS(setxattr), 0) != + 0 || + seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ENOTSUP), SCMP_SYS(lsetxattr), 0) != + 0 || + seccomp_rule_add(ctx, SCMP_ACT_ERRNO(ENOTSUP), SCMP_SYS(fsetxattr), 0) != + 0) { + throw SysError("unable to add seccomp rule"); + } + + if (seccomp_attr_set(ctx, SCMP_FLTATR_CTL_NNP, + settings.allowNewPrivileges ? 0 : 1) != 0) { + throw SysError("unable to set 'no new privileges' seccomp attribute"); + } + + if (seccomp_load(ctx) != 0) { + throw SysError("unable to load seccomp BPF program"); + } +#else + throw Error( + "seccomp is not supported on this platform; " + "you can bypass this error by setting the option 'filter-syscalls' to " + "false, but note that untrusted builds can then create setuid binaries!"); +#endif +#endif +} + +void DerivationGoal::runChild() { + /* Warning: in the child we should absolutely not make any SQLite + calls! */ + + try { /* child */ + + commonChildInit(builderOut); + + try { + setupSeccomp(); + } catch (...) { + if (buildUser) { + throw; + } + } + + bool setUser = true; + + /* Make the contents of netrc available to builtin:fetchurl + (which may run under a different uid and/or in a sandbox). */ + std::string netrcData; + try { + if (drv->isBuiltin() && drv->builder == "builtin:fetchurl") { + const std::string& netrc_file = settings.netrcFile; + netrcData = readFile(netrc_file); + } + } catch (SysError&) { + } + +#if __linux__ + if (useChroot) { + userNamespaceSync.writeSide = AutoCloseFD(-1); + + if (drainFD(userNamespaceSync.readSide.get()) != "1") { + throw Error("user namespace initialisation failed"); + } + + userNamespaceSync.readSide = AutoCloseFD(-1); + + if (privateNetwork) { + /* Initialise the loopback interface. */ + AutoCloseFD fd(socket(PF_INET, SOCK_DGRAM, IPPROTO_IP)); + if (!fd) { + throw SysError("cannot open IP socket"); + } + + struct ifreq ifr; + strncpy(ifr.ifr_name, "lo", sizeof("lo")); + ifr.ifr_flags = IFF_UP | IFF_LOOPBACK | IFF_RUNNING; + if (ioctl(fd.get(), SIOCSIFFLAGS, &ifr) == -1) { + throw SysError("cannot set loopback interface flags"); + } + } + + /* Set the hostname etc. to fixed values. */ + char hostname[] = "localhost"; + if (sethostname(hostname, sizeof(hostname)) == -1) { + throw SysError("cannot set host name"); + } + char domainname[] = "(none)"; // kernel default + if (setdomainname(domainname, sizeof(domainname)) == -1) { + throw SysError("cannot set domain name"); + } + + /* Make all filesystems private. This is necessary + because subtrees may have been mounted as "shared" + (MS_SHARED). (Systemd does this, for instance.) Even + though we have a private mount namespace, mounting + filesystems on top of a shared subtree still propagates + outside of the namespace. Making a subtree private is + local to the namespace, though, so setting MS_PRIVATE + does not affect the outside world. */ + if (mount(nullptr, "/", nullptr, MS_REC | MS_PRIVATE, nullptr) == -1) { + throw SysError("unable to make '/' private mount"); + } + + /* Bind-mount chroot directory to itself, to treat it as a + different filesystem from /, as needed for pivot_root. */ + if (mount(chrootRootDir.c_str(), chrootRootDir.c_str(), nullptr, MS_BIND, + nullptr) == -1) { + throw SysError(format("unable to bind mount '%1%'") % chrootRootDir); + } + + /* Set up a nearly empty /dev, unless the user asked to + bind-mount the host /dev. */ + Strings ss; + if (dirsInChroot.find("/dev") == dirsInChroot.end()) { + createDirs(chrootRootDir + "/dev/shm"); + createDirs(chrootRootDir + "/dev/pts"); + ss.push_back("/dev/full"); + if ((settings.systemFeatures.get().count("kvm") != 0u) && + pathExists("/dev/kvm")) { + ss.push_back("/dev/kvm"); + } + ss.push_back("/dev/null"); + ss.push_back("/dev/random"); + ss.push_back("/dev/tty"); + ss.push_back("/dev/urandom"); + ss.push_back("/dev/zero"); + createSymlink("/proc/self/fd", chrootRootDir + "/dev/fd"); + createSymlink("/proc/self/fd/0", chrootRootDir + "/dev/stdin"); + createSymlink("/proc/self/fd/1", chrootRootDir + "/dev/stdout"); + createSymlink("/proc/self/fd/2", chrootRootDir + "/dev/stderr"); + } + + /* Fixed-output derivations typically need to access the + network, so give them access to /etc/resolv.conf and so + on. */ + if (fixedOutput) { + ss.push_back("/etc/resolv.conf"); + + // Only use nss functions to resolve hosts and + // services. Donโt use it for anything else that may + // be configured for this system. This limits the + // potential impurities introduced in fixed outputs. + writeFile(chrootRootDir + "/etc/nsswitch.conf", + "hosts: files dns\nservices: files\n"); + + ss.push_back("/etc/services"); + ss.push_back("/etc/hosts"); + if (pathExists("/var/run/nscd/socket")) { + ss.push_back("/var/run/nscd/socket"); + } + } + + for (auto& i : ss) { + dirsInChroot.emplace(i, i); + } + + /* Bind-mount all the directories from the "host" + filesystem that we want in the chroot + environment. */ + auto doBind = [&](const Path& source, const Path& target, + bool optional = false) { + DLOG(INFO) << "bind mounting '" << source << "' to '" << target << "'"; + struct stat st; + if (stat(source.c_str(), &st) == -1) { + if (optional && errno == ENOENT) { + return; + } + throw SysError("getting attributes of path '%1%'", source); + } + if (S_ISDIR(st.st_mode)) { + createDirs(target); + } else { + createDirs(dirOf(target)); + writeFile(target, ""); + } + if (mount(source.c_str(), target.c_str(), "", MS_BIND | MS_REC, + nullptr) == -1) { + throw SysError("bind mount from '%1%' to '%2%' failed", source, + target); + } + }; + + for (auto& i : dirsInChroot) { + if (i.second.source == "/proc") { + continue; + } // backwards compatibility + doBind(i.second.source, chrootRootDir + i.first, i.second.optional); + } + + /* Bind a new instance of procfs on /proc. */ + createDirs(chrootRootDir + "/proc"); + if (mount("none", (chrootRootDir + "/proc").c_str(), "proc", 0, + nullptr) == -1) { + throw SysError("mounting /proc"); + } + + /* Mount a new tmpfs on /dev/shm to ensure that whatever + the builder puts in /dev/shm is cleaned up automatically. */ + if (pathExists("/dev/shm") && + mount("none", (chrootRootDir + "/dev/shm").c_str(), "tmpfs", 0, + fmt("size=%s", settings.sandboxShmSize).c_str()) == -1) { + throw SysError("mounting /dev/shm"); + } + + /* Mount a new devpts on /dev/pts. Note that this + requires the kernel to be compiled with + CONFIG_DEVPTS_MULTIPLE_INSTANCES=y (which is the case + if /dev/ptx/ptmx exists). */ + if (pathExists("/dev/pts/ptmx") && + !pathExists(chrootRootDir + "/dev/ptmx") && + (dirsInChroot.count("/dev/pts") == 0u)) { + if (mount("none", (chrootRootDir + "/dev/pts").c_str(), "devpts", 0, + "newinstance,mode=0620") == 0) { + createSymlink("/dev/pts/ptmx", chrootRootDir + "/dev/ptmx"); + + /* Make sure /dev/pts/ptmx is world-writable. With some + Linux versions, it is created with permissions 0. */ + chmod_(chrootRootDir + "/dev/pts/ptmx", 0666); + } else { + if (errno != EINVAL) { + throw SysError("mounting /dev/pts"); + } + doBind("/dev/pts", chrootRootDir + "/dev/pts"); + doBind("/dev/ptmx", chrootRootDir + "/dev/ptmx"); + } + } + + /* Do the chroot(). */ + if (chdir(chrootRootDir.c_str()) == -1) { + throw SysError(format("cannot change directory to '%1%'") % + chrootRootDir); + } + + if (mkdir("real-root", 0) == -1) { + throw SysError("cannot create real-root directory"); + } + + if (pivot_root(".", "real-root") == -1) { + throw SysError(format("cannot pivot old root directory onto '%1%'") % + (chrootRootDir + "/real-root")); + } + + if (chroot(".") == -1) { + throw SysError(format("cannot change root directory to '%1%'") % + chrootRootDir); + } + + if (umount2("real-root", MNT_DETACH) == -1) { + throw SysError("cannot unmount real root filesystem"); + } + + if (rmdir("real-root") == -1) { + throw SysError("cannot remove real-root directory"); + } + + /* Switch to the sandbox uid/gid in the user namespace, + which corresponds to the build user or calling user in + the parent namespace. */ + if (setgid(sandboxGid) == -1) { + throw SysError("setgid failed"); + } + if (setuid(sandboxUid) == -1) { + throw SysError("setuid failed"); + } + + setUser = false; + } +#endif + + if (chdir(tmpDirInSandbox.c_str()) == -1) { + throw SysError(format("changing into '%1%'") % tmpDir); + } + + /* Close all other file descriptors. */ + closeMostFDs({STDIN_FILENO, STDOUT_FILENO, STDERR_FILENO}); + +#if __linux__ + /* Change the personality to 32-bit if we're doing an + i686-linux build on an x86_64-linux machine. */ + struct utsname utsbuf; + uname(&utsbuf); + if (drv->platform == "i686-linux" && + (settings.thisSystem == "x86_64-linux" || + ((strcmp(utsbuf.sysname, "Linux") == 0) && + (strcmp(utsbuf.machine, "x86_64") == 0)))) { + if (personality(PER_LINUX32) == -1) { + throw SysError("cannot set i686-linux personality"); + } + } + + /* Impersonate a Linux 2.6 machine to get some determinism in + builds that depend on the kernel version. */ + if ((drv->platform == "i686-linux" || drv->platform == "x86_64-linux") && + settings.impersonateLinux26) { + int cur = personality(0xffffffff); + if (cur != -1) { + personality(cur | 0x0020000 /* == UNAME26 */); + } + } + + /* Disable address space randomization for improved + determinism. */ + int cur = personality(0xffffffff); + if (cur != -1) { + personality(cur | ADDR_NO_RANDOMIZE); + } +#endif + + /* Disable core dumps by default. */ + struct rlimit limit = {0, RLIM_INFINITY}; + setrlimit(RLIMIT_CORE, &limit); + + // FIXME: set other limits to deterministic values? + + /* Fill in the environment. */ + Strings envStrs; + for (auto& i : env) { + envStrs.push_back( + rewriteStrings(i.first + "=" + i.second, inputRewrites)); + } + + /* If we are running in `build-users' mode, then switch to the + user we allocated above. Make sure that we drop all root + privileges. Note that above we have closed all file + descriptors except std*, so that's safe. Also note that + setuid() when run as root sets the real, effective and + saved UIDs. */ + if (setUser && buildUser) { + /* Preserve supplementary groups of the build user, to allow + admins to specify groups such as "kvm". */ + if (!buildUser->getSupplementaryGIDs().empty() && + setgroups(buildUser->getSupplementaryGIDs().size(), + buildUser->getSupplementaryGIDs().data()) == -1) { + throw SysError("cannot set supplementary groups of build user"); + } + + if (setgid(buildUser->getGID()) == -1 || + getgid() != buildUser->getGID() || getegid() != buildUser->getGID()) { + throw SysError("setgid failed"); + } + + if (setuid(buildUser->getUID()) == -1 || + getuid() != buildUser->getUID() || geteuid() != buildUser->getUID()) { + throw SysError("setuid failed"); + } + } + + /* Fill in the arguments. */ + Strings args; + + const char* builder = "invalid"; + + if (!drv->isBuiltin()) { + builder = drv->builder.c_str(); + std::string builderBasename = baseNameOf(drv->builder); + args.push_back(builderBasename); + } + + for (auto& i : drv->args) { + args.push_back(rewriteStrings(i, inputRewrites)); + } + + /* Indicate that we managed to set up the build environment. */ + writeFull(STDERR_FILENO, std::string("\1\n")); + + /* Execute the program. This should not return. */ + if (drv->isBuiltin()) { + try { + BasicDerivation drv2(*drv); + for (auto& e : drv2.env) { + e.second = rewriteStrings(e.second, inputRewrites); + } + + if (drv->builder == "builtin:fetchurl") { + builtinFetchurl(drv2, netrcData); + } else if (drv->builder == "builtin:buildenv") { + builtinBuildenv(drv2); + } else { + throw Error(format("unsupported builtin function '%1%'") % + std::string(drv->builder, 8)); + } + _exit(0); + } catch (std::exception& e) { + writeFull(STDERR_FILENO, "error: " + std::string(e.what()) + "\n"); + _exit(1); + } + } + + execve(builder, stringsToCharPtrs(args).data(), + stringsToCharPtrs(envStrs).data()); + + throw SysError(format("executing '%1%'") % drv->builder); + + } catch (std::exception& e) { + writeFull(STDERR_FILENO, "\1while setting up the build environment: " + + std::string(e.what()) + "\n"); + _exit(1); + } +} + +/* Parse a list of reference specifiers. Each element must either be + a store path, or the symbolic name of the output of the derivation + (such as `out'). */ +PathSet parseReferenceSpecifiers(Store& store, const BasicDerivation& drv, + const Strings& paths) { + PathSet result; + for (auto& i : paths) { + if (store.isStorePath(i)) { + result.insert(i); + } else if (drv.outputs.find(i) != drv.outputs.end()) { + result.insert(drv.outputs.find(i)->second.path); + } else { + throw BuildError( + format("derivation contains an illegal reference specifier '%1%'") % + i); + } + } + return result; +} + +void DerivationGoal::registerOutputs() { + /* When using a build hook, the build hook can register the output + as valid (by doing `nix-store --import'). If so we don't have + to do anything here. */ + if (hook) { + bool allValid = true; + for (auto& i : drv->outputs) { + if (!worker.store.isValidPath(i.second.path)) { + allValid = false; + } + } + if (allValid) { + return; + } + } + + std::map<std::string, ValidPathInfo> infos; + + /* Set of inodes seen during calls to canonicalisePathMetaData() + for this build's outputs. This needs to be shared between + outputs to allow hard links between outputs. */ + InodesSeen inodesSeen; + + Path checkSuffix = ".check"; + bool keepPreviousRound = settings.keepFailed || settings.runDiffHook; + + std::exception_ptr delayedException; + + /* Check whether the output paths were created, and grep each + output path to determine what other paths it references. Also make all + output paths read-only. */ + for (auto& i : drv->outputs) { + Path path = i.second.path; + if (missingPaths.find(path) == missingPaths.end()) { + continue; + } + + ValidPathInfo info; + + Path actualPath = path; + if (useChroot) { + actualPath = chrootRootDir + path; + if (pathExists(actualPath)) { + /* Move output paths from the chroot to the Nix store. */ + if (buildMode == bmRepair) { + replaceValidPath(path, actualPath); + } else if (buildMode != bmCheck && + rename(actualPath.c_str(), + worker.store.toRealPath(path).c_str()) == -1) { + throw SysError(format("moving build output '%1%' from the sandbox to " + "the Nix store") % + path); + } + } + if (buildMode != bmCheck) { + actualPath = worker.store.toRealPath(path); + } + } + + if (needsHashRewrite()) { + Path redirected = redirectedOutputs[path]; + if (buildMode == bmRepair && + redirectedBadOutputs.find(path) != redirectedBadOutputs.end() && + pathExists(redirected)) { + replaceValidPath(path, redirected); + } + if (buildMode == bmCheck && !redirected.empty()) { + actualPath = redirected; + } + } + + struct stat st; + if (lstat(actualPath.c_str(), &st) == -1) { + if (errno == ENOENT) { + throw BuildError( + format("builder for '%1%' failed to produce output path '%2%'") % + drvPath % path); + } + throw SysError(format("getting attributes of path '%1%'") % actualPath); + } + +#ifndef __CYGWIN__ + /* Check that the output is not group or world writable, as + that means that someone else can have interfered with the + build. Also, the output should be owned by the build + user. */ + if ((!S_ISLNK(st.st_mode) && ((st.st_mode & (S_IWGRP | S_IWOTH)) != 0u)) || + (buildUser && st.st_uid != buildUser->getUID())) { + throw BuildError(format("suspicious ownership or permission on '%1%'; " + "rejecting this build output") % + path); + } +#endif + + /* Apply hash rewriting if necessary. */ + bool rewritten = false; + if (!outputRewrites.empty()) { + LOG(WARNING) << "rewriting hashes in '" << path << "'; cross fingers"; + + /* Canonicalise first. This ensures that the path we're + rewriting doesn't contain a hard link to /etc/shadow or + something like that. */ + canonicalisePathMetaData(actualPath, buildUser ? buildUser->getUID() : -1, + inodesSeen); + + /* FIXME: this is in-memory. */ + StringSink sink; + dumpPath(actualPath, sink); + deletePath(actualPath); + sink.s = make_ref<std::string>(rewriteStrings(*sink.s, outputRewrites)); + StringSource source(*sink.s); + restorePath(actualPath, source); + + rewritten = true; + } + + /* Check that fixed-output derivations produced the right + outputs (i.e., the content hash should match the specified + hash). */ + if (fixedOutput) { + bool recursive; + Hash h; + i.second.parseHashInfo(recursive, h); + + if (!recursive) { + /* The output path should be a regular file without + execute permission. */ + if (!S_ISREG(st.st_mode) || (st.st_mode & S_IXUSR) != 0) { + throw BuildError( + format( + "output path '%1%' should be a non-executable regular file") % + path); + } + } + + /* Check the hash. In hash mode, move the path produced by + the derivation to its content-addressed location. */ + Hash h2 = recursive ? hashPath(h.type, actualPath).first + : hashFile(h.type, actualPath); + + Path dest = worker.store.makeFixedOutputPath(recursive, h2, + storePathToName(path)); + + if (h != h2) { + /* Throw an error after registering the path as + valid. */ + worker.hashMismatch = true; + delayedException = std::make_exception_ptr( + BuildError("hash mismatch in fixed-output derivation '%s':\n " + "wanted: %s\n got: %s", + dest, h.to_string(), h2.to_string())); + + Path actualDest = worker.store.toRealPath(dest); + + if (worker.store.isValidPath(dest)) { + std::rethrow_exception(delayedException); + } + + if (actualPath != actualDest) { + PathLocks outputLocks({actualDest}); + deletePath(actualDest); + if (rename(actualPath.c_str(), actualDest.c_str()) == -1) { + throw SysError(format("moving '%1%' to '%2%'") % actualPath % dest); + } + } + + path = dest; + actualPath = actualDest; + } else { + assert(path == dest); + } + + info.ca = makeFixedOutputCA(recursive, h2); + } + + /* Get rid of all weird permissions. This also checks that + all files are owned by the build user, if applicable. */ + canonicalisePathMetaData(actualPath, + buildUser && !rewritten ? buildUser->getUID() : -1, + inodesSeen); + + /* For this output path, find the references to other paths + contained in it. Compute the SHA-256 NAR hash at the same + time. The hash is stored in the database so that we can + verify later on whether nobody has messed with the store. */ + DLOG(INFO) << "scanning for references inside '" << path << "'"; + HashResult hash; + PathSet references = scanForReferences(actualPath, allPaths, hash); + + if (buildMode == bmCheck) { + if (!worker.store.isValidPath(path)) { + continue; + } + auto info = *worker.store.queryPathInfo(path); + if (hash.first != info.narHash) { + worker.checkMismatch = true; + if (settings.runDiffHook || settings.keepFailed) { + Path dst = worker.store.toRealPath(path + checkSuffix); + deletePath(dst); + if (rename(actualPath.c_str(), dst.c_str()) != 0) { + throw SysError(format("renaming '%1%' to '%2%'") % actualPath % + dst); + } + + handleDiffHook(buildUser ? buildUser->getUID() : getuid(), + buildUser ? buildUser->getGID() : getgid(), path, dst, + drvPath, tmpDir, log_sink()); + + throw NotDeterministic( + format("derivation '%1%' may not be deterministic: output '%2%' " + "differs from '%3%'") % + drvPath % path % dst); + } + throw NotDeterministic(format("derivation '%1%' may not be " + "deterministic: output '%2%' differs") % + drvPath % path); + } + + /* Since we verified the build, it's now ultimately + trusted. */ + if (!info.ultimate) { + info.ultimate = true; + worker.store.signPathInfo(info); + worker.store.registerValidPaths({info}); + } + + continue; + } + + /* For debugging, print out the referenced and unreferenced + paths. */ + for (auto& i : inputPaths) { + auto j = references.find(i); + if (j == references.end()) { + DLOG(INFO) << "unreferenced input: '" << i << "'"; + } else { + DLOG(INFO) << "referenced input: '" << i << "'"; + } + } + + if (curRound == nrRounds) { + worker.store.optimisePath( + actualPath); // FIXME: combine with scanForReferences() + worker.markContentsGood(path); + } + + info.path = path; + info.narHash = hash.first; + info.narSize = hash.second; + info.references = references; + info.deriver = drvPath; + info.ultimate = true; + worker.store.signPathInfo(info); + + if (!info.references.empty()) { + info.ca.clear(); + } + + infos[i.first] = info; + } + + if (buildMode == bmCheck) { + return; + } + + /* Apply output checks. */ + checkOutputs(infos); + + /* Compare the result with the previous round, and report which + path is different, if any.*/ + if (curRound > 1 && prevInfos != infos) { + assert(prevInfos.size() == infos.size()); + for (auto i = prevInfos.begin(), j = infos.begin(); i != prevInfos.end(); + ++i, ++j) { + if (!(*i == *j)) { + result.isNonDeterministic = true; + Path prev = i->second.path + checkSuffix; + bool prevExists = keepPreviousRound && pathExists(prev); + auto msg = + prevExists + ? fmt("output '%1%' of '%2%' differs from '%3%' from previous " + "round", + i->second.path, drvPath, prev) + : fmt("output '%1%' of '%2%' differs from previous round", + i->second.path, drvPath); + + handleDiffHook(buildUser ? buildUser->getUID() : getuid(), + buildUser ? buildUser->getGID() : getgid(), prev, + i->second.path, drvPath, tmpDir, log_sink()); + + if (settings.enforceDeterminism) { + throw NotDeterministic(msg); + } + + log_sink() << msg << std::endl; + curRound = nrRounds; // we know enough, bail out early + } + } + } + + /* If this is the first round of several, then move the output out + of the way. */ + if (nrRounds > 1 && curRound == 1 && curRound < nrRounds && + keepPreviousRound) { + for (auto& i : drv->outputs) { + Path prev = i.second.path + checkSuffix; + deletePath(prev); + Path dst = i.second.path + checkSuffix; + if (rename(i.second.path.c_str(), dst.c_str()) != 0) { + throw SysError(format("renaming '%1%' to '%2%'") % i.second.path % dst); + } + } + } + + if (curRound < nrRounds) { + prevInfos = infos; + return; + } + + /* Remove the .check directories if we're done. FIXME: keep them + if the result was not determistic? */ + if (curRound == nrRounds) { + for (auto& i : drv->outputs) { + Path prev = i.second.path + checkSuffix; + deletePath(prev); + } + } + + /* Register each output path as valid, and register the sets of + paths referenced by each of them. If there are cycles in the + outputs, this will fail. */ + { + ValidPathInfos infos2; + for (auto& i : infos) { + infos2.push_back(i.second); + } + worker.store.registerValidPaths(infos2); + } + + /* In case of a fixed-output derivation hash mismatch, throw an + exception now that we have registered the output as valid. */ + if (delayedException) { + std::rethrow_exception(delayedException); + } +} + +void DerivationGoal::checkOutputs( + const std::map<Path, ValidPathInfo>& outputs) { + std::map<Path, const ValidPathInfo&> outputsByPath; + for (auto& output : outputs) { + outputsByPath.emplace(output.second.path, output.second); + } + + for (auto& output : outputs) { + auto& outputName = output.first; + auto& info = output.second; + + struct Checks { + bool ignoreSelfRefs = false; + std::optional<uint64_t> maxSize, maxClosureSize; + std::optional<Strings> allowedReferences, allowedRequisites, + disallowedReferences, disallowedRequisites; + }; + + /* Compute the closure and closure size of some output. This + is slightly tricky because some of its references (namely + other outputs) may not be valid yet. */ + auto getClosure = [&](const Path& path) { + uint64_t closureSize = 0; + PathSet pathsDone; + std::queue<Path> pathsLeft; + pathsLeft.push(path); + + while (!pathsLeft.empty()) { + auto path = pathsLeft.front(); + pathsLeft.pop(); + if (!pathsDone.insert(path).second) { + continue; + } + + auto i = outputsByPath.find(path); + if (i != outputsByPath.end()) { + closureSize += i->second.narSize; + for (auto& ref : i->second.references) { + pathsLeft.push(ref); + } + } else { + auto info = worker.store.queryPathInfo(path); + closureSize += info->narSize; + for (auto& ref : info->references) { + pathsLeft.push(ref); + } + } + } + + return std::make_pair(pathsDone, closureSize); + }; + + auto applyChecks = [&](const Checks& checks) { + if (checks.maxSize && info.narSize > *checks.maxSize) { + throw BuildError( + "path '%s' is too large at %d bytes; limit is %d bytes", info.path, + info.narSize, *checks.maxSize); + } + + if (checks.maxClosureSize) { + uint64_t closureSize = getClosure(info.path).second; + if (closureSize > *checks.maxClosureSize) { + throw BuildError( + "closure of path '%s' is too large at %d bytes; limit is %d " + "bytes", + info.path, closureSize, *checks.maxClosureSize); + } + } + + auto checkRefs = [&](const std::optional<Strings>& value, bool allowed, + bool recursive) { + if (!value) { + return; + } + + PathSet spec = parseReferenceSpecifiers(worker.store, *drv, *value); + + PathSet used = + recursive ? getClosure(info.path).first : info.references; + + if (recursive && checks.ignoreSelfRefs) { + used.erase(info.path); + } + + PathSet badPaths; + + for (auto& i : used) { + if (allowed) { + if (spec.count(i) == 0u) { + badPaths.insert(i); + } + } else { + if (spec.count(i) != 0u) { + badPaths.insert(i); + } + } + } + + if (!badPaths.empty()) { + std::string badPathsStr; + for (auto& i : badPaths) { + badPathsStr += "\n "; + badPathsStr += i; + } + throw BuildError( + "output '%s' is not allowed to refer to the following paths:%s", + info.path, badPathsStr); + } + }; + + checkRefs(checks.allowedReferences, true, false); + checkRefs(checks.allowedRequisites, true, true); + checkRefs(checks.disallowedReferences, false, false); + checkRefs(checks.disallowedRequisites, false, true); + }; + + if (auto structuredAttrs = parsedDrv->getStructuredAttrs()) { + auto outputChecks = structuredAttrs->find("outputChecks"); + if (outputChecks != structuredAttrs->end()) { + auto output = outputChecks->find(outputName); + + if (output != outputChecks->end()) { + Checks checks; + + auto maxSize = output->find("maxSize"); + if (maxSize != output->end()) { + checks.maxSize = maxSize->get<uint64_t>(); + } + + auto maxClosureSize = output->find("maxClosureSize"); + if (maxClosureSize != output->end()) { + checks.maxClosureSize = maxClosureSize->get<uint64_t>(); + } + + auto get = [&](const std::string& name) -> std::optional<Strings> { + auto i = output->find(name); + if (i != output->end()) { + Strings res; + for (auto& j : *i) { + if (!j.is_string()) { + throw Error( + "attribute '%s' of derivation '%s' must be a list of " + "strings", + name, drvPath); + } + res.push_back(j.get<std::string>()); + } + checks.disallowedRequisites = res; + return res; + } + return {}; + }; + + checks.allowedReferences = get("allowedReferences"); + checks.allowedRequisites = get("allowedRequisites"); + checks.disallowedReferences = get("disallowedReferences"); + checks.disallowedRequisites = get("disallowedRequisites"); + + applyChecks(checks); + } + } + } else { + // legacy non-structured-attributes case + Checks checks; + checks.ignoreSelfRefs = true; + checks.allowedReferences = parsedDrv->getStringsAttr("allowedReferences"); + checks.allowedRequisites = parsedDrv->getStringsAttr("allowedRequisites"); + checks.disallowedReferences = + parsedDrv->getStringsAttr("disallowedReferences"); + checks.disallowedRequisites = + parsedDrv->getStringsAttr("disallowedRequisites"); + applyChecks(checks); + } + } +} + +Path DerivationGoal::openLogFile() { + logSize = 0; + + if (!settings.keepLog) { + return ""; + } + + std::string baseName = baseNameOf(drvPath); + + /* Create a log file. */ + Path dir = fmt("%s/%s/%s/", worker.store.logDir, nix::LocalStore::drvsLogDir, + std::string(baseName, 0, 2)); + createDirs(dir); + + Path logFileName = fmt("%s/%s%s", dir, std::string(baseName, 2), + settings.compressLog ? ".bz2" : ""); + + fdLogFile = AutoCloseFD(open(logFileName.c_str(), + O_CREAT | O_WRONLY | O_TRUNC | O_CLOEXEC, 0666)); + if (!fdLogFile) { + throw SysError(format("creating log file '%1%'") % logFileName); + } + + logFileSink = std::make_shared<FdSink>(fdLogFile.get()); + + if (settings.compressLog) { + logSink = std::shared_ptr<CompressionSink>( + makeCompressionSink("bzip2", *logFileSink)); + } else { + logSink = logFileSink; + } + + return logFileName; +} + +void DerivationGoal::closeLogFile() { + auto logSink2 = std::dynamic_pointer_cast<CompressionSink>(logSink); + if (logSink2) { + logSink2->finish(); + } + if (logFileSink) { + logFileSink->flush(); + } + logSink = logFileSink = nullptr; + fdLogFile = AutoCloseFD(-1); +} + +void DerivationGoal::deleteTmpDir(bool force) { + if (!tmpDir.empty()) { + /* Don't keep temporary directories for builtins because they + might have privileged stuff (like a copy of netrc). */ + if (settings.keepFailed && !force && !drv->isBuiltin()) { + log_sink() << "note: keeping build directory '" << tmpDir << "'" + << std::endl; + chmod(tmpDir.c_str(), 0755); + } else { + deletePath(tmpDir); + } + tmpDir = ""; + } +} + +// TODO(tazjin): What ... what does this function ... do? +void DerivationGoal::handleChildOutput(int fd, const std::string& data) { + if ((hook && fd == hook->builderOut.readSide.get()) || + (!hook && fd == builderOut.readSide.get())) { + logSize += data.size(); + if (settings.maxLogSize && logSize > settings.maxLogSize) { + log_sink() << getName() << " killed after writing more than " + << settings.maxLogSize << " bytes of log output" << std::endl; + killChild(); + done(BuildResult::LogLimitExceeded); + return; + } + + for (auto c : data) { + if (c == '\r') { + currentLogLinePos = 0; + } else if (c == '\n') { + flushLine(); + } else { + if (currentLogLinePos >= currentLogLine.size()) { + currentLogLine.resize(currentLogLinePos + 1); + } + currentLogLine[currentLogLinePos++] = c; + } + } + + if (logSink) { + (*logSink)(data); + } + } + + if (hook && fd == hook->fromHook.readSide.get()) { + for (auto c : data) { + if (c == '\n') { + currentHookLine.clear(); + } else { + currentHookLine += c; + } + } + } +} + +void DerivationGoal::handleEOF(int /* fd */) { + if (!currentLogLine.empty()) { + flushLine(); + } + worker.wakeUp(shared_from_this()); +} + +void DerivationGoal::flushLine() { + if (settings.verboseBuild && + (settings.printRepeatedBuilds || curRound == 1)) { + log_sink() << currentLogLine << std::endl; + } else { + logTail.push_back(currentLogLine); + if (logTail.size() > settings.logLines) { + logTail.pop_front(); + } + } + + currentLogLine = ""; + currentLogLinePos = 0; +} + +PathSet DerivationGoal::checkPathValidity(bool returnValid, bool checkHash) { + PathSet result; + for (auto& i : drv->outputs) { + if (!wantOutput(i.first, wantedOutputs)) { + continue; + } + bool good = worker.store.isValidPath(i.second.path) && + (!checkHash || worker.pathContentsGood(i.second.path)); + if (good == returnValid) { + result.insert(i.second.path); + } + } + return result; +} + +Path DerivationGoal::addHashRewrite(const Path& path) { + std::string h1 = std::string(path, worker.store.storeDir.size() + 1, 32); + std::string h2 = + std::string(hashString(htSHA256, "rewrite:" + drvPath + ":" + path) + .to_string(Base32, false), + 0, 32); + Path p = worker.store.storeDir + "/" + h2 + + std::string(path, worker.store.storeDir.size() + 33); + deletePath(p); + assert(path.size() == p.size()); + inputRewrites[h1] = h2; + outputRewrites[h2] = h1; + redirectedOutputs[path] = p; + return p; +} + +void DerivationGoal::done(BuildResult::Status status, const std::string& msg) { + result.status = status; + result.errorMsg = msg; + amDone(result.success() ? ecSuccess : ecFailed); + if (result.status == BuildResult::TimedOut) { + worker.timedOut = true; + } + if (result.status == BuildResult::PermanentFailure) { + worker.permanentFailure = true; + } + + mcExpectedBuilds.reset(); + mcRunningBuilds.reset(); + + if (result.success()) { + if (status == BuildResult::Built) { + worker.doneBuilds++; + } + } else { + if (status != BuildResult::DependencyFailed) { + worker.failedBuilds++; + } + } +} + +////////////////////////////////////////////////////////////////////// + +class SubstitutionGoal : public Goal { + friend class Worker; + + private: + /* The store path that should be realised through a substitute. */ + Path storePath; + + /* The remaining substituters. */ + std::list<ref<Store>> subs; + + /* The current substituter. */ + std::shared_ptr<Store> sub; + + /* Whether a substituter failed. */ + bool substituterFailed = false; + + /* Path info returned by the substituter's query info operation. */ + std::shared_ptr<const ValidPathInfo> info; + + /* Pipe for the substituter's standard output. */ + Pipe outPipe; + + /* The substituter thread. */ + std::thread thr; + + std::promise<void> promise; + + /* Whether to try to repair a valid path. */ + RepairFlag repair; + + /* Location where we're downloading the substitute. Differs from + storePath when doing a repair. */ + Path destPath; + + std::unique_ptr<MaintainCount<uint64_t>> maintainExpectedSubstitutions, + maintainRunningSubstitutions, maintainExpectedNar, + maintainExpectedDownload; + + using GoalState = void (SubstitutionGoal::*)(); + GoalState state; + + public: + SubstitutionGoal(Worker& worker, const Path& storePath, + RepairFlag repair = NoRepair); + + ~SubstitutionGoal() override; + + void timedOut() override { abort(); }; + + std::string key() override { + /* "a$" ensures substitution goals happen before derivation + goals. */ + return "a$" + storePathToName(storePath) + "$" + storePath; + } + + void work() override; + + /* The states. */ + void init(); + void tryNext(); + void gotInfo(); + void referencesValid(); + void tryToRun(); + void finished(); + + /* Callback used by the worker to write to the log. */ + void handleChildOutput(int fd, const std::string& data) override; + void handleEOF(int fd) override; + + Path getStorePath() { return storePath; } + + void amDone(ExitCode result) override { Goal::amDone(result); } +}; + +SubstitutionGoal::SubstitutionGoal(Worker& worker, const Path& storePath, + RepairFlag repair) + : Goal(worker), repair(repair) { + this->storePath = storePath; + state = &SubstitutionGoal::init; + name = absl::StrCat("substitution of ", storePath); + trace("created"); + maintainExpectedSubstitutions = + std::make_unique<MaintainCount<uint64_t>>(worker.expectedSubstitutions); +} + +SubstitutionGoal::~SubstitutionGoal() { + try { + if (thr.joinable()) { + // FIXME: signal worker thread to quit. + thr.join(); + worker.childTerminated(this); + } + } catch (...) { + ignoreException(); + } +} + +void SubstitutionGoal::work() { (this->*state)(); } + +void SubstitutionGoal::init() { + trace("init"); + + worker.store.addTempRoot(storePath); + + /* If the path already exists we're done. */ + if ((repair == 0u) && worker.store.isValidPath(storePath)) { + amDone(ecSuccess); + return; + } + + if (settings.readOnlyMode) { + throw Error( + format( + "cannot substitute path '%1%' - no write access to the Nix store") % + storePath); + } + + subs = settings.useSubstitutes ? getDefaultSubstituters() + : std::list<ref<Store>>(); + + tryNext(); +} + +void SubstitutionGoal::tryNext() { + trace("trying next substituter"); + + if (subs.empty()) { + /* None left. Terminate this goal and let someone else deal + with it. */ + DLOG(WARNING) + << "path '" << storePath + << "' is required, but there is no substituter that can build it"; + + /* Hack: don't indicate failure if there were no substituters. + In that case the calling derivation should just do a + build. */ + amDone(substituterFailed ? ecFailed : ecNoSubstituters); + + if (substituterFailed) { + worker.failedSubstitutions++; + } + + return; + } + + sub = subs.front(); + subs.pop_front(); + + if (sub->storeDir != worker.store.storeDir) { + tryNext(); + return; + } + + try { + // FIXME: make async + info = sub->queryPathInfo(storePath); + } catch (InvalidPath&) { + tryNext(); + return; + } catch (SubstituterDisabled&) { + if (settings.tryFallback) { + tryNext(); + return; + } + throw; + } catch (Error& e) { + if (settings.tryFallback) { + log_sink() << e.what() << std::endl; + tryNext(); + return; + } + throw; + } + + /* Update the total expected download size. */ + auto narInfo = std::dynamic_pointer_cast<const NarInfo>(info); + + maintainExpectedNar = std::make_unique<MaintainCount<uint64_t>>( + worker.expectedNarSize, info->narSize); + + maintainExpectedDownload = + narInfo && (narInfo->fileSize != 0u) + ? std::make_unique<MaintainCount<uint64_t>>( + worker.expectedDownloadSize, narInfo->fileSize) + : nullptr; + + /* Bail out early if this substituter lacks a valid + signature. LocalStore::addToStore() also checks for this, but + only after we've downloaded the path. */ + if (worker.store.requireSigs && !sub->isTrusted && + (info->checkSignatures(worker.store, worker.store.getPublicKeys()) == + 0u)) { + log_sink() << "substituter '" << sub->getUri() + << "' does not have a valid signature for path '" << storePath + << "'" << std::endl; + tryNext(); + return; + } + + /* To maintain the closure invariant, we first have to realise the + paths referenced by this one. */ + for (auto& i : info->references) { + if (i != storePath) { /* ignore self-references */ + addWaitee(worker.makeSubstitutionGoal(i)); + } + } + + if (waitees.empty()) { /* to prevent hang (no wake-up event) */ + referencesValid(); + } else { + state = &SubstitutionGoal::referencesValid; + } +} + +void SubstitutionGoal::referencesValid() { + trace("all references realised"); + + if (nrFailed > 0) { + DLOG(WARNING) << "some references of path '" << storePath + << "' could not be realised"; + amDone(nrNoSubstituters > 0 || nrIncompleteClosure > 0 ? ecIncompleteClosure + : ecFailed); + return; + } + + for (auto& i : info->references) { + if (i != storePath) { /* ignore self-references */ + assert(worker.store.isValidPath(i)); + } + } + + state = &SubstitutionGoal::tryToRun; + worker.wakeUp(shared_from_this()); +} + +void SubstitutionGoal::tryToRun() { + trace("trying to run"); + + /* Make sure that we are allowed to start a build. Note that even + if maxBuildJobs == 0 (no local builds allowed), we still allow + a substituter to run. This is because substitutions cannot be + distributed to another machine via the build hook. */ + if (worker.getNrLocalBuilds() >= + std::max(1U, (unsigned int)settings.maxBuildJobs)) { + worker.waitForBuildSlot(shared_from_this()); + return; + } + + maintainRunningSubstitutions = + std::make_unique<MaintainCount<uint64_t>>(worker.runningSubstitutions); + + outPipe.create(); + + promise = std::promise<void>(); + + thr = std::thread([this]() { + try { + /* Wake up the worker loop when we're done. */ + Finally updateStats([this]() { outPipe.writeSide = AutoCloseFD(-1); }); + + copyStorePath(ref<Store>(sub), + ref<Store>(worker.store.shared_from_this()), storePath, + repair, sub->isTrusted ? NoCheckSigs : CheckSigs); + + promise.set_value(); + } catch (...) { + promise.set_exception(std::current_exception()); + } + }); + + worker.childStarted(shared_from_this(), {outPipe.readSide.get()}, true, + false); + + state = &SubstitutionGoal::finished; +} + +void SubstitutionGoal::finished() { + trace("substitute finished"); + + thr.join(); + worker.childTerminated(this); + + try { + promise.get_future().get(); + } catch (std::exception& e) { + log_sink() << e.what() << std::endl; + + /* Cause the parent build to fail unless --fallback is given, + or the substitute has disappeared. The latter case behaves + the same as the substitute never having existed in the + first place. */ + try { + throw; + } catch (SubstituteGone&) { + } catch (...) { + substituterFailed = true; + } + + /* Try the next substitute. */ + state = &SubstitutionGoal::tryNext; + worker.wakeUp(shared_from_this()); + return; + } + + worker.markContentsGood(storePath); + + DLOG(INFO) << "substitution of path '" << storePath << "' succeeded"; + + maintainRunningSubstitutions.reset(); + + maintainExpectedSubstitutions.reset(); + worker.doneSubstitutions++; + + if (maintainExpectedDownload) { + auto fileSize = maintainExpectedDownload->delta; + maintainExpectedDownload.reset(); + worker.doneDownloadSize += fileSize; + } + + worker.doneNarSize += maintainExpectedNar->delta; + maintainExpectedNar.reset(); + + amDone(ecSuccess); +} + +void SubstitutionGoal::handleChildOutput(int fd, const std::string& data) {} + +void SubstitutionGoal::handleEOF(int fd) { + if (fd == outPipe.readSide.get()) { + worker.wakeUp(shared_from_this()); + } +} + +////////////////////////////////////////////////////////////////////// + +ABSL_CONST_INIT static thread_local bool working = false; + +Worker::Worker(LocalStore& store, std::ostream& log_sink) + : log_sink_(log_sink), store(store) { + // Debugging: prevent recursive workers. + // TODO(grfn): Do we need this? + CHECK(!working) << "Worker initialized during execution of a worker"; + working = true; + nrLocalBuilds = 0; + lastWokenUp = steady_time_point::min(); + permanentFailure = false; + timedOut = false; + hashMismatch = false; + checkMismatch = false; +} + +Worker::~Worker() { + working = false; + + /* Explicitly get rid of all strong pointers now. After this all + goals that refer to this worker should be gone. (Otherwise we + are in trouble, since goals may call childTerminated() etc. in + their destructors). */ + topGoals.clear(); + + assert(expectedSubstitutions == 0); + assert(expectedDownloadSize == 0); + assert(expectedNarSize == 0); +} + +GoalPtr Worker::makeDerivationGoal(const Path& drv_path, + const StringSet& wantedOutputs, + BuildMode buildMode) { + GoalPtr goal = derivationGoals[drv_path].lock(); + if (!goal) { + goal = std::make_shared<DerivationGoal>(*this, drv_path, wantedOutputs, + buildMode); + derivationGoals[drv_path] = goal; + wakeUp(goal); + } else { + (dynamic_cast<DerivationGoal*>(goal.get())) + ->addWantedOutputs(wantedOutputs); + } + return goal; +} + +std::shared_ptr<DerivationGoal> Worker::makeBasicDerivationGoal( + const Path& drvPath, const BasicDerivation& drv, BuildMode buildMode) { + std::shared_ptr<DerivationGoal> goal = + std::make_shared<DerivationGoal>(*this, drvPath, drv, buildMode); + wakeUp(goal); + return goal; +} + +GoalPtr Worker::makeSubstitutionGoal(const Path& path, RepairFlag repair) { + GoalPtr goal = substitutionGoals[path].lock(); + if (!goal) { + goal = std::make_shared<SubstitutionGoal>(*this, path, repair); + substitutionGoals[path] = goal; + wakeUp(goal); + } + return goal; +} + +static void removeGoal(const GoalPtr& goal, WeakGoalMap& goalMap) { + /* !!! inefficient */ + for (auto i = goalMap.begin(); i != goalMap.end();) { + if (i->second.lock() == goal) { + auto j = i; + ++j; + goalMap.erase(i); + i = j; + } else { + ++i; + } + } +} + +void Worker::removeGoal(const GoalPtr& goal) { + nix::removeGoal(goal, derivationGoals); + nix::removeGoal(goal, substitutionGoals); + if (topGoals.find(goal) != topGoals.end()) { + topGoals.erase(goal); + /* If a top-level goal failed, then kill all other goals + (unless keepGoing was set). */ + if (goal->getExitCode() == Goal::ecFailed && !settings.keepGoing) { + topGoals.clear(); + } + } + + /* Wake up goals waiting for any goal to finish. */ + for (auto& i : waitingForAnyGoal) { + GoalPtr goal = i.lock(); + if (goal) { + wakeUp(goal); + } + } + + waitingForAnyGoal.clear(); +} + +void Worker::wakeUp(const GoalPtr& goal) { + goal->trace("woken up"); + addToWeakGoals(awake, goal); +} + +unsigned Worker::getNrLocalBuilds() { return nrLocalBuilds; } + +void Worker::childStarted(const GoalPtr& goal, const std::set<int>& fds, + bool inBuildSlot, bool respectTimeouts) { + Child child; + child.goal = goal; + child.goal2 = goal.get(); + child.fds = fds; + child.timeStarted = child.lastOutput = steady_time_point::clock::now(); + child.inBuildSlot = inBuildSlot; + child.respectTimeouts = respectTimeouts; + children.emplace_back(child); + if (inBuildSlot) { + nrLocalBuilds++; + } +} + +void Worker::childTerminated(Goal* goal, bool wakeSleepers) { + auto i = + std::find_if(children.begin(), children.end(), + [&](const Child& child) { return child.goal2 == goal; }); + if (i == children.end()) { + return; + } + + if (i->inBuildSlot) { + assert(nrLocalBuilds > 0); + nrLocalBuilds--; + } + + children.erase(i); + + if (wakeSleepers) { + /* Wake up goals waiting for a build slot. */ + for (auto& j : wantingToBuild) { + GoalPtr goal = j.lock(); + if (goal) { + wakeUp(goal); + } + } + + wantingToBuild.clear(); + } +} + +void Worker::waitForBuildSlot(const GoalPtr& goal) { + DLOG(INFO) << "wait for build slot"; + if (getNrLocalBuilds() < settings.maxBuildJobs) { + wakeUp(goal); /* we can do it right away */ + } else { + addToWeakGoals(wantingToBuild, goal); + } +} + +void Worker::waitForAnyGoal(GoalPtr goal) { + DLOG(INFO) << "wait for any goal"; + addToWeakGoals(waitingForAnyGoal, std::move(goal)); +} + +void Worker::waitForAWhile(GoalPtr goal) { + DLOG(INFO) << "wait for a while"; + addToWeakGoals(waitingForAWhile, std::move(goal)); +} + +void Worker::run(const Goals& _topGoals) { + for (auto& i : _topGoals) { + topGoals.insert(i); + } + + DLOG(INFO) << "entered goal loop"; + + while (true) { + checkInterrupt(); + + store.autoGC(false); + + /* Call every wake goal (in the ordering established by + CompareGoalPtrs). */ + while (!awake.empty() && !topGoals.empty()) { + Goals awake2; + for (auto& i : awake) { + GoalPtr goal = i.lock(); + if (goal) { + awake2.insert(goal); + } + } + awake.clear(); + for (auto& goal : awake2) { + checkInterrupt(); + goal->work(); + if (topGoals.empty()) { + break; + } // stuff may have been cancelled + } + } + + if (topGoals.empty()) { + break; + } + + /* Wait for input. */ + if (!children.empty() || !waitingForAWhile.empty()) { + waitForInput(); + } else { + if (awake.empty() && 0 == settings.maxBuildJobs) { + throw Error( + "unable to start any build; either increase '--max-jobs' " + "or enable remote builds"); + } + assert(!awake.empty()); + } + } + + /* If --keep-going is not set, it's possible that the main goal + exited while some of its subgoals were still active. But if + --keep-going *is* set, then they must all be finished now. */ + assert(!settings.keepGoing || awake.empty()); + assert(!settings.keepGoing || wantingToBuild.empty()); + assert(!settings.keepGoing || children.empty()); +} + +void Worker::waitForInput() { + DLOG(INFO) << "waiting for children"; + + /* Process output from the file descriptors attached to the + children, namely log output and output path creation commands. + We also use this to detect child termination: if we get EOF on + the logger pipe of a build, we assume that the builder has + terminated. */ + + bool useTimeout = false; + struct timeval timeout; + timeout.tv_usec = 0; + auto before = steady_time_point::clock::now(); + + /* If we're monitoring for silence on stdout/stderr, or if there + is a build timeout, then wait for input until the first + deadline for any child. */ + auto nearest = steady_time_point::max(); // nearest deadline + if (settings.minFree.get() != 0) { + // Periodicallty wake up to see if we need to run the garbage collector. + nearest = before + std::chrono::seconds(10); + } + for (auto& i : children) { + if (!i.respectTimeouts) { + continue; + } + if (0 != settings.maxSilentTime) { + nearest = std::min( + nearest, i.lastOutput + std::chrono::seconds(settings.maxSilentTime)); + } + if (0 != settings.buildTimeout) { + nearest = std::min( + nearest, i.timeStarted + std::chrono::seconds(settings.buildTimeout)); + } + } + if (nearest != steady_time_point::max()) { + timeout.tv_sec = std::max( + 1L, static_cast<long>(std::chrono::duration_cast<std::chrono::seconds>( + nearest - before) + .count())); + useTimeout = true; + } + + /* If we are polling goals that are waiting for a lock, then wake + up after a few seconds at most. */ + if (!waitingForAWhile.empty()) { + useTimeout = true; + if (lastWokenUp == steady_time_point::min()) { + DLOG(WARNING) << "waiting for locks or build slots..."; + } + if (lastWokenUp == steady_time_point::min() || lastWokenUp > before) { + lastWokenUp = before; + } + timeout.tv_sec = std::max( + 1L, static_cast<long>(std::chrono::duration_cast<std::chrono::seconds>( + lastWokenUp + + std::chrono::seconds(settings.pollInterval) - + before) + .count())); + } else { + lastWokenUp = steady_time_point::min(); + } + + if (useTimeout) { + DLOG(INFO) << "sleeping " << timeout.tv_sec << " seconds"; + } + + /* Use select() to wait for the input side of any logger pipe to + become `available'. Note that `available' (i.e., non-blocking) + includes EOF. */ + fd_set fds; + FD_ZERO(&fds); + int fdMax = 0; + for (auto& i : children) { + for (auto& j : i.fds) { + if (j >= FD_SETSIZE) { + throw Error("reached FD_SETSIZE limit"); + } + FD_SET(j, &fds); + if (j >= fdMax) { + fdMax = j + 1; + } + } + } + + if (select(fdMax, &fds, nullptr, nullptr, useTimeout ? &timeout : nullptr) == + -1) { + if (errno == EINTR) { + return; + } + throw SysError("waiting for input"); + } + + auto after = steady_time_point::clock::now(); + + /* Process all available file descriptors. FIXME: this is + O(children * fds). */ + decltype(children)::iterator i; + for (auto j = children.begin(); j != children.end(); j = i) { + i = std::next(j); + + checkInterrupt(); + + GoalPtr goal = j->goal.lock(); + assert(goal); + + std::set<int> fds2(j->fds); + std::vector<unsigned char> buffer(4096); + for (auto& k : fds2) { + if (FD_ISSET(k, &fds)) { + ssize_t rd = read(k, buffer.data(), buffer.size()); + // FIXME: is there a cleaner way to handle pt close + // than EIO? Is this even standard? + if (rd == 0 || (rd == -1 && errno == EIO)) { + DLOG(WARNING) << goal->getName() << ": got EOF"; + goal->handleEOF(k); + j->fds.erase(k); + } else if (rd == -1) { + if (errno != EINTR) { + throw SysError("%s: read failed", goal->getName()); + } + } else { + DLOG(INFO) << goal->getName() << ": read " << rd << " bytes"; + std::string data(reinterpret_cast<char*>(buffer.data()), rd); + j->lastOutput = after; + goal->handleChildOutput(k, data); + } + } + } + + if (goal->getExitCode() == Goal::ecBusy && 0 != settings.maxSilentTime && + j->respectTimeouts && + after - j->lastOutput >= std::chrono::seconds(settings.maxSilentTime)) { + log_sink_ << goal->getName() << " timed out after " + << settings.maxSilentTime << " seconds of silence"; + goal->timedOut(); + } + + else if (goal->getExitCode() == Goal::ecBusy && + 0 != settings.buildTimeout && j->respectTimeouts && + after - j->timeStarted >= + std::chrono::seconds(settings.buildTimeout)) { + log_sink_ << goal->getName() << " timed out after " + << settings.buildTimeout << " seconds"; + goal->timedOut(); + } + } + + if (!waitingForAWhile.empty() && + lastWokenUp + std::chrono::seconds(settings.pollInterval) <= after) { + lastWokenUp = after; + for (auto& i : waitingForAWhile) { + GoalPtr goal = i.lock(); + if (goal) { + wakeUp(goal); + } + } + waitingForAWhile.clear(); + } +} + +unsigned int Worker::exitStatus() { + /* + * 1100100 + * ^^^^ + * |||`- timeout + * ||`-- output hash mismatch + * |`--- build failure + * `---- not deterministic + */ + unsigned int mask = 0; + bool buildFailure = permanentFailure || timedOut || hashMismatch; + if (buildFailure) { + mask |= 0x04; // 100 + } + if (timedOut) { + mask |= 0x01; // 101 + } + if (hashMismatch) { + mask |= 0x02; // 102 + } + if (checkMismatch) { + mask |= 0x08; // 104 + } + + if (mask != 0u) { + mask |= 0x60; + } + return mask != 0u ? mask : 1; +} + +bool Worker::pathContentsGood(const Path& path) { + auto i = pathContentsGoodCache.find(path); + if (i != pathContentsGoodCache.end()) { + return i->second; + } + log_sink_ << "checking path '" << path << "'..."; + auto info = store.queryPathInfo(path); + bool res; + if (!pathExists(path)) { + res = false; + } else { + HashResult current = hashPath(info->narHash.type, path); + Hash nullHash(htSHA256); + res = info->narHash == nullHash || info->narHash == current.first; + } + pathContentsGoodCache[path] = res; + if (!res) { + log_sink_ << "path '" << path << "' is corrupted or missing!"; + } + return res; +} + +void Worker::markContentsGood(const Path& path) { + pathContentsGoodCache[path] = true; +} + +////////////////////////////////////////////////////////////////////// + +static void primeCache(Store& store, const PathSet& paths) { + PathSet willBuild; + PathSet willSubstitute; + PathSet unknown; + unsigned long long downloadSize; + unsigned long long narSize; + store.queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize, + narSize); + + if (!willBuild.empty() && 0 == settings.maxBuildJobs && + getMachines().empty()) { + throw Error( + "%d derivations need to be built, but neither local builds " + "('--max-jobs') " + "nor remote builds ('--builders') are enabled", + willBuild.size()); + } +} + +absl::Status LocalStore::buildPaths(std::ostream& log_sink, + const PathSet& drvPaths, + BuildMode build_mode) { + Worker worker(*this, log_sink); + + primeCache(*this, drvPaths); + + Goals goals; + for (auto& i : drvPaths) { + DrvPathWithOutputs i2 = parseDrvPathWithOutputs(i); + if (isDerivation(i2.first)) { + goals.insert(worker.makeDerivationGoal(i2.first, i2.second, build_mode)); + } else { + goals.insert(worker.makeSubstitutionGoal( + i, build_mode == bmRepair ? Repair : NoRepair)); + } + } + + worker.run(goals); + + PathSet failed; + for (auto& i : goals) { + if (i->getExitCode() != Goal::ecSuccess) { + auto* i2 = dynamic_cast<DerivationGoal*>(i.get()); + if (i2 != nullptr) { + failed.insert(i2->getDrvPath()); + } else { + failed.insert(dynamic_cast<SubstitutionGoal*>(i.get())->getStorePath()); + } + } + } + + if (!failed.empty()) { + return absl::Status( + absl::StatusCode::kInternal, + absl::StrFormat("build of %s failed (exit code %d)", showPaths(failed), + worker.exitStatus())); + } + return absl::OkStatus(); +} + +BuildResult LocalStore::buildDerivation(std::ostream& log_sink, + const Path& drvPath, + const BasicDerivation& drv, + BuildMode buildMode) { + Worker worker(*this, log_sink); + auto goal = worker.makeBasicDerivationGoal(drvPath, drv, buildMode); + + BuildResult result; + + try { + worker.run(Goals{goal}); + result = goal->getResult(); + } catch (Error& e) { + result.status = BuildResult::MiscFailure; + result.errorMsg = e.msg(); + } + + return result; +} + +void LocalStore::ensurePath(const Path& path) { + /* If the path is already valid, we're done. */ + if (isValidPath(path)) { + return; + } + + primeCache(*this, {path}); + + auto discard_logs = DiscardLogsSink(); + Worker worker(*this, discard_logs); + GoalPtr goal = worker.makeSubstitutionGoal(path); + Goals goals = {goal}; + + worker.run(goals); + + if (goal->getExitCode() != Goal::ecSuccess) { + throw Error(worker.exitStatus(), + "path '%s' does not exist and cannot be created", path); + } +} + +void LocalStore::repairPath(const Path& path) { + auto discard_logs = DiscardLogsSink(); + Worker worker(*this, discard_logs); + GoalPtr goal = worker.makeSubstitutionGoal(path, Repair); + Goals goals = {goal}; + + worker.run(goals); + + if (goal->getExitCode() != Goal::ecSuccess) { + /* Since substituting the path didn't work, if we have a valid + deriver, then rebuild the deriver. */ + auto deriver = queryPathInfo(path)->deriver; + if (!deriver.empty() && isValidPath(deriver)) { + goals.clear(); + goals.insert(worker.makeDerivationGoal(deriver, StringSet(), bmRepair)); + worker.run(goals); + } else { + throw Error(worker.exitStatus(), "cannot repair path '%s'", path); + } + } +} + +} // namespace nix |