#include "references.hh" #include "pathlocks.hh" #include "globals.hh" #include "local-store.hh" #include "util.hh" #include "archive.hh" #include "affinity.hh" #include "builtins.hh" #include "download.hh" #include "finally.hh" #include "compression.hh" #include "json.hh" #include "nar-info.hh" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* Includes required for chroot support. */ #if __linux__ #include #include #include #include #include #include #include #include #include #include #if HAVE_SECCOMP #include #endif #define pivot_root(new_root, put_old) (syscall(SYS_pivot_root, new_root, put_old)) #endif #if HAVE_STATVFS #include #endif #include namespace nix { using std::map; static string pathNullDevice = "/dev/null"; /* Forward definition. */ class Worker; struct HookInstance; /* A pointer to a goal. */ class Goal; class DerivationGoal; typedef std::shared_ptr GoalPtr; typedef std::weak_ptr WeakGoalPtr; struct CompareGoalPtrs { bool operator() (const GoalPtr & a, const GoalPtr & b) const; }; /* Set of goals. */ typedef set Goals; typedef list WeakGoals; /* A map of paths to goals (and the other way around). */ typedef map WeakGoalMap; class Goal : public std::enable_shared_from_this { public: typedef enum {ecBusy, ecSuccess, ecFailed, ecNoSubstituters, ecIncompleteClosure} ExitCode; 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. */ string name; /* Whether the goal is finished. */ ExitCode exitCode; Goal(Worker & worker) : worker(worker) { nrFailed = nrNoSubstituters = nrIncompleteClosure = 0; exitCode = ecBusy; } virtual ~Goal() { trace("goal destroyed"); } public: virtual void work() = 0; void addWaitee(GoalPtr waitee); virtual void waiteeDone(GoalPtr waitee, ExitCode result); virtual void handleChildOutput(int fd, const string & data) { abort(); } virtual void handleEOF(int fd) { abort(); } void trace(const FormatOrString & fs); 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 string key() = 0; protected: virtual void amDone(ExitCode result); }; bool CompareGoalPtrs::operator() (const GoalPtr & a, const GoalPtr & b) const { string s1 = a->key(); string s2 = b->key(); return s1 < s2; } typedef std::chrono::time_point steady_time_point; /* 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 set 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 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 pathContentsGoodCache; public: const Activity act; const Activity actDerivations; const Activity actSubstitutions; /* 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; LocalStore & store; std::unique_ptr 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); ~Worker(); /* Make a goal (with caching). */ GoalPtr makeDerivationGoal(const Path & drvPath, const StringSet & wantedOutputs, BuildMode buildMode = bmNormal); std::shared_ptr makeBasicDerivationGoal(const Path & drvPath, const BasicDerivation & drv, BuildMode buildMode = bmNormal); GoalPtr makeSubstitutionGoal(const Path & storePath, RepairFlag repair = NoRepair); /* Remove a dead goal. */ void removeGoal(GoalPtr goal); /* Wake up a goal (i.e., there is something for it to do). */ void wakeUp(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(GoalPtr goal, const set & 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(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); void updateProgress() { actDerivations.progress(doneBuilds, expectedBuilds + doneBuilds, runningBuilds, failedBuilds); actSubstitutions.progress(doneSubstitutions, expectedSubstitutions + doneSubstitutions, runningSubstitutions, failedSubstitutions); act.setExpected(actDownload, expectedDownloadSize + doneDownloadSize); act.setExpected(actCopyPath, expectedNarSize + doneNarSize); } }; ////////////////////////////////////////////////////////////////////// void addToWeakGoals(WeakGoals & goals, GoalPtr p) { // FIXME: necessary? // FIXME: O(n) for (auto & i : goals) if (i.lock() == p) return; goals.push_back(p); } void Goal::addWaitee(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) { debug("%1%: %2%", 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(pathNullDevice.c_str(), O_RDWR); if (fdDevNull == -1) throw SysError(format("cannot open '%1%'") % pathNullDevice); if (dup2(fdDevNull, STDIN_FILENO) == -1) throw SysError("cannot dup null device into stdin"); close(fdDevNull); } ////////////////////////////////////////////////////////////////////// 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 lockedPaths_; Path fnUserLock; AutoCloseFD fdUserLock; string user; uid_t uid; gid_t gid; std::vector supplementaryGIDs; public: UserLock(); ~UserLock(); void kill(); string getUser() { return user; } uid_t getUID() { assert(uid); return uid; } uid_t getGID() { assert(gid); return gid; } std::vector getSupplementaryGIDs() { return supplementaryGIDs; } bool enabled() { return uid != 0; } }; Sync 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) 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; ++p) { debug(format("found build user '%1%'") % *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) { debug(format("trying user '%1%'") % i); struct passwd * pw = getpwnam(i.c_str()); if (!pw) 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)) /* 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; std::map activities; HookInstance(); ~HookInstance(); }; HookInstance::HookInstance() { debug("starting build hook '%s'", 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), }; execv(settings.buildHook.get().c_str(), stringsToCharPtrs(args).data()); throw SysError("executing '%s'", settings.buildHook); }); pid.setSeparatePG(true); fromHook.writeSide = -1; toHook.readSide = -1; sink = FdSink(toHook.writeSide.get()); std::map settings; globalConfig.getSettings(settings); for (auto & setting : settings) sink << 1 << setting.first << setting.second.value; sink << 0; } HookInstance::~HookInstance() { try { toHook.writeSide = -1; if (pid != -1) pid.kill(); } catch (...) { ignoreException(); } } ////////////////////////////////////////////////////////////////////// typedef map StringRewrites; std::string rewriteStrings(std::string s, const StringRewrites & rewrites) { for (auto & i : rewrites) { size_t j = 0; while ((j = s.find(i.first, j)) != string::npos) s.replace(j, i.first.size(), i.second); } return s; } ////////////////////////////////////////////////////////////////////// typedef enum {rpAccept, rpDecline, rpPostpone} HookReply; 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 drv; /* The contents of drv->env["__json"]. */ std::experimental::optional structuredAttrs; /* 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 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 logFileSink, logSink; /* Number of bytes received from the builder's stdout/stderr. */ unsigned long logSize; /* The most recent log lines. */ std::list 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 hook; /* Whether we're currently doing a chroot build. */ bool useChroot = false; Path chrootRootDir; /* RAII object to delete the chroot directory. */ std::shared_ptr autoDelChroot; /* Whether this is a fixed-output derivation. */ bool fixedOutput; /* Whether to run the build in a private network namespace. */ bool privateNetwork = false; typedef void (DerivationGoal::*GoalState)(); GoalState state; /* Stuff we need to pass to initChild(). */ struct ChrootPath { Path source; bool optional; ChrootPath(Path source = "", bool optional = false) : source(source), optional(optional) { } }; typedef map DirsInChroot; // maps target path to source path DirsInChroot dirsInChroot; typedef map Environment; Environment env; #if __APPLE__ typedef string SandboxProfile; SandboxProfile additionalSandboxProfile; #endif /* Hash rewriting. */ StringRewrites inputRewrites, outputRewrites; typedef map RedirectedOutputs; 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. */ ValidPathInfos prevInfos; const uid_t sandboxUid = 1000; const gid_t sandboxGid = 100; const static Path homeDir; std::unique_ptr> mcExpectedBuilds, mcRunningBuilds; std::unique_ptr act; std::map builderActivities; /* The remote machine on which we're building. */ std::string machineName; public: DerivationGoal(const Path & drvPath, const StringSet & wantedOutputs, Worker & worker, BuildMode buildMode = bmNormal); DerivationGoal(const Path & drvPath, const BasicDerivation & drv, Worker & worker, BuildMode buildMode = bmNormal); ~DerivationGoal(); void timedOut() override; 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(); /* Get an attribute from drv->env or from drv->env["__json"]. */ std::experimental::optional getAttr(const std::string & name); bool getBoolAttr(const std::string & name, bool def = false); std::experimental::optional getStringsAttr(const std::string & name); /* 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 *); /* Check that the derivation outputs all exist and register them as valid. */ void registerOutputs(); /* 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 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 string & msg = ""); PathSet exportReferences(PathSet storePaths); }; const Path DerivationGoal::homeDir = "/homeless-shelter"; DerivationGoal::DerivationGoal(const Path & drvPath, const StringSet & wantedOutputs, Worker & worker, BuildMode buildMode) : Goal(worker) , useDerivation(true) , drvPath(drvPath) , wantedOutputs(wantedOutputs) , buildMode(buildMode) { state = &DerivationGoal::getDerivation; name = (format("building of '%1%'") % drvPath).str(); trace("created"); mcExpectedBuilds = std::make_unique>(worker.expectedBuilds); worker.updateProgress(); } DerivationGoal::DerivationGoal(const Path & drvPath, const BasicDerivation & drv, Worker & worker, BuildMode buildMode) : Goal(worker) , useDerivation(false) , drvPath(drvPath) , buildMode(buildMode) { this->drv = std::unique_ptr(new BasicDerivation(drv)); state = &DerivationGoal::haveDerivation; name = (format("building of %1%") % showPaths(drv.outputPaths())).str(); trace("created"); mcExpectedBuilds = std::make_unique>(worker.expectedBuilds); worker.updateProgress(); /* 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(); } } void DerivationGoal::killChild() { if (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(-pid, SIGKILL); /* ignore the result */ buildUser->kill(); pid.wait(); } else pid.kill(); assert(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) { printError(format("cannot build missing derivation '%1%'") % drvPath); 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(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.size() == 0 && buildMode == bmNormal) { done(BuildResult::AlreadyValid); return; } /* Parse the __json attribute, if any. */ auto jsonAttr = drv->env.find("__json"); if (jsonAttr != drv->env.end()) { try { structuredAttrs = nlohmann::json::parse(jsonAttr->second); } catch (std::exception & e) { throw Error("cannot process __json attribute of '%s': %s", drvPath, e.what()); } } /* 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 && drv->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(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 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; printError(format("found corrupted or missing path '%1%' in the output closure of '%2%'") % i % drvPath); Path drvPath2 = outputsToDrv[i]; if (drvPath2 == "") 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); printError( format("cannot build derivation '%1%': %2% dependencies couldn't be built") % drvPath % nrFailed); 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) { debug(format("building path '%1%'") % i.second.path); allPaths.insert(i.second.path); } /* Determine the full set of input paths. */ /* First, the input derivations. */ if (useDerivation) for (auto & i : dynamic_cast(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); debug(format("added input paths %1%") % 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()) { debug(format("skipping build of derivation '%1%', someone beat us to it") % drvPath); 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; debug(format("removing invalid path '%1%'") % 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 || drv->willBuildLocally(); auto started = [&]() { auto msg = fmt( buildMode == bmRepair ? "repairing outputs of '%s'" : buildMode == bmCheck ? "checking outputs of '%s'" : nrRounds > 1 ? "building '%s' (round %d/%d)" : "building '%s'", drvPath, curRound, nrRounds); fmt("building '%s'", drvPath); if (hook) msg += fmt(" on '%s'", machineName); act = std::make_unique(*logger, lvlInfo, actBuild, msg, Logger::Fields{drvPath, hook ? machineName : "", curRound, nrRounds}); mcRunningBuilds = std::make_unique>(worker.runningBuilds); worker.updateProgress(); }; /* 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(0); // 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) { printError(e.msg()); 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(); debug(format("builder process for '%1%' finished") % drvPath); result.timesBuilt++; result.stopTime = time(0); /* So the child is gone now. */ worker.childTerminated(this); /* Close the read side of the logger pipe. */ if (hook) { hook->builderOut.readSide = -1; hook->fromHook.readSide = -1; } else builderOut.readSide = -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 && (unsigned long long) st.f_bavail * st.f_bsize < required) diskFull = true; if (statvfs(tmpDir.c_str(), &st) == 0 && (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 (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) { printError(e.msg()); 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(&e) ? 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(); try { /* Tell the hook about system features (beyond the system type) required from the build machine. (The hook could parse the drv file itself, but this is easier.) */ auto features = getStringsAttr("requiredSystemFeatures").value_or(Strings()); for (auto & i : features) checkStoreName(i); /* !!! abuse */ /* Send the request to the hook. */ worker.hook->sink << "try" << (worker.getNrLocalBuilds() < settings.maxBuildJobs ? 1 : 0) << drv->platform << drvPath << features; worker.hook->sink.flush(); /* Read the first line of input, which should be a word indicating whether the hook wishes to perform the build. */ string reply; while (true) { string s = readLine(worker.hook->fromHook.readSide.get()); if (handleJSONLogMessage(s, worker.act, worker.hook->activities, true)) ; else if (string(s, 0, 2) == "# ") { reply = string(s, 2); break; } else { s += "\n"; writeToStderr(s); } } debug(format("hook reply is '%1%'") % reply); if (reply == "decline") return rpDecline; else if (reply == "decline-permanently") { worker.tryBuildHook = false; worker.hook = 0; 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) { printError("build hook died unexpectedly: %s", chomp(drainFD(worker.hook->fromHook.readSide.get()))); worker.hook = 0; return rpDecline; } else 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 = -1; /* Create the log file and pipe. */ Path logFile = openLogFile(); set 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) { ((DerivationGoal *) arg)->runChild(); return 1; } PathSet DerivationGoal::exportReferences(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)) 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 = NULL; if (getaddrinfo("this.pre-initializes.the.dns.resolvers.invalid.", "http", NULL, &res) != 0) { if (res) freeaddrinfo(res); } }); } void DerivationGoal::startBuilder() { /* Right platform? */ if (!drv->canBuildLocally()) { throw Error( format("a '%1%' is required to build '%3%', but I am a '%2%'") % drv->platform % settings.thisSystem % drvPath); } if (drv->isBuiltin()) preloadNSS(); #if __APPLE__ additionalSandboxProfile = getAttr("__sandboxProfile").value_or(""); #endif /* Are we doing a chroot build? */ { auto noChroot = 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); #if __APPLE__ if (additionalSandboxProfile != "") throw Error(format("derivation '%1%' specifies a sandbox profile, " "but this is only allowed when 'sandbox' is 'relaxed'") % drvPath); #endif useChroot = true; } else if (settings.sandboxMode == smDisabled) useChroot = false; else if (settings.sandboxMode == smRelaxed) useChroot = !fixedOutput && !noChroot; } if (worker.store.storeDir != worker.store.realStoreDir) { #if __linux__ useChroot = true; #else throw Error("building using a diverted store is not supported on this platform"); #endif } /* 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) { #if defined(__linux__) || defined(__APPLE__) buildUser = std::make_unique(); /* Make sure that no other processes are executing under this uid. */ buildUser->kill(); #else /* Don't know how to block the creation of setuid/setgid binaries on this platform. */ throw Error("build users are not supported on this platform for security reasons"); #endif } /* Create a temporary directory where the build will take place. */ auto drvName = storePathToName(drvPath); tmpDir = createTempDir("", "nix-build-" + drvName, false, false, 0700); /* In a sandbox, for determinism, always use the same temporary directory. */ #if __linux__ tmpDirInSandbox = useChroot ? settings.sandboxBuildDir : tmpDir; #else tmpDirInSandbox = tmpDir; #endif 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 (!structuredAttrs) { /* 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. */ string s = get(drv->env, "exportReferencesGraph"); Strings ss = tokenizeString(s); if (ss.size() % 2 != 0) throw BuildError(format("odd number of tokens in 'exportReferencesGraph': '%1%'") % s); for (Strings::iterator i = ss.begin(); i != ss.end(); ) { string fileName = *i++; checkStoreName(fileName); /* !!! abuse of this function */ Path storePath = *i++; /* Write closure info to . */ 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 == string::npos) dirsInChroot[i] = {i, optional}; else dirsInChroot[string(i, 0, p)] = {string(i, p + 1), optional}; } dirsInChroot[tmpDirInSandbox] = 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] = i; PathSet allowedPaths = settings.allowedImpureHostPrefixes; /* This works like the above, except on a per-derivation level */ auto impurePaths = 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] = i; } #if __linux__ /* 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(chrootRootDir); printMsg(lvlChatty, format("setting up chroot environment in '%1%'") % 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)) throw SysError(format("getting attributes of path '%1%'") % i); if (S_ISDIR(st.st_mode)) dirsInChroot[i] = r; else { Path p = chrootRootDir + i; debug("linking '%1%' to '%2%'", p, 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); #elif __APPLE__ /* We don't really have any parent prep work to do (yet?) All work happens in the child, instead. */ #else throw Error("sandboxing builds is not supported on this platform"); #endif } else { 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.size() > 0) 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(drv.get())) { printMsg(lvlChatty, format("executing pre-build hook '%1%'") % 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 != 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 == "") { state = stBegin; } else { auto p = line.find('='); if (p == string::npos) dirsInChroot[line] = line; else dirsInChroot[string(line, 0, p)] = string(line, p + 1); } } } } /* Run the builder. */ printMsg(lvlChatty, format("executing builder '%1%'") % drv->builder); /* Create the log file. */ Path logFile = openLogFile(); /* Create a pipe to get the output of the builder. */ builderOut.create(); result.startTime = time(0); /* 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(); options.allowVfork = false; 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, 0) == -1) throw SysError("setgroups failed"); size_t stackSize = 1 * 1024 * 1024; char * stack = (char *) mmap(0, 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. */ child = clone(childEntry, stack + stackSize, flags & ~CLONE_NEWPID, this); if (child == -1) throw SysError("cloning builder process"); writeFull(builderOut.writeSide.get(), std::to_string(child) + "\n"); _exit(0); }, options); if (helper.wait() != 0) throw Error("unable to start build process"); userNamespaceSync.readSide = -1; pid_t tmp; if (!string2Int(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(pid) + "/uid_map", (format("%d %d 1") % sandboxUid % hostUid).str()); writeFile("/proc/" + std::to_string(pid) + "/setgroups", "deny"); writeFile("/proc/" + std::to_string(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 = -1; } else #endif { options.allowVfork = !buildUser && !drv->isBuiltin(); pid = startProcess([&]() { runChild(); }, options); } /* parent */ pid.setSeparatePG(true); builderOut.writeSide = -1; worker.childStarted(shared_from_this(), {builderOut.readSide.get()}, true, true); /* Check if setting up the build environment failed. */ while (true) { string msg = readLine(builderOut.readSide.get()); if (string(msg, 0, 1) == "\1") { if (msg.size() == 1) break; throw Error(string(msg, 1)); } debug(msg); } } 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(); /* 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 (!structuredAttrs) { StringSet passAsFile = tokenizeString(get(drv->env, "passAsFile")); int fileNr = 0; for (auto & i : drv->env) { if (passAsFile.find(i.first) == passAsFile.end()) { env[i.first] = i.second; } else { string fn = ".attr-" + std::to_string(fileNr++); Path p = tmpDir + "/" + fn; writeFile(p, i.second); 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; /* 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 : getStringsAttr("impureEnvVars").value_or(Strings())) env[i] = getEnv(i); } /* 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"; } std::experimental::optional DerivationGoal::getAttr(const std::string & name) { if (structuredAttrs) { auto i = structuredAttrs->find(name); if (i == structuredAttrs->end()) return {}; else { if (!i->is_string()) throw Error("attribute '%s' of derivation '%s' must be a string", name, drvPath); return i->get(); } } else { auto i = drv->env.find(name); if (i == drv->env.end()) return {}; else return i->second; } } bool DerivationGoal::getBoolAttr(const std::string & name, bool def) { if (structuredAttrs) { auto i = structuredAttrs->find(name); if (i == structuredAttrs->end()) return def; else { if (!i->is_boolean()) throw Error("attribute '%s' of derivation '%s' must be a Boolean", name, drvPath); return i->get(); } } else { auto i = drv->env.find(name); if (i == drv->env.end()) return def; else return i->second == "1"; } } std::experimental::optional DerivationGoal::getStringsAttr(const std::string & name) { if (structuredAttrs) { auto i = structuredAttrs->find(name); if (i == structuredAttrs->end()) return {}; else { if (!i->is_array()) throw Error("attribute '%s' of derivation '%s' must be a list of strings", name, drvPath); Strings res; for (auto j = i->begin(); j != i->end(); ++j) { if (!j->is_string()) throw Error("attribute '%s' of derivation '%s' must be a list of strings", name, drvPath); res.push_back(j->get()); } return res; } } else { auto i = drv->env.find(name); if (i == drv->env.end()) return {}; else return tokenizeString(i->second); } } static std::regex shVarName("[A-Za-z_][A-Za-z0-9_]*"); void DerivationGoal::writeStructuredAttrs() { 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()); 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)); /* 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::experimental::optional { if (value.is_string()) return shellEscape(value); if (value.is_number()) { auto f = value.get(); if (std::ceil(f) == f) return std::to_string(value.get()); } if (value.is_null()) return std::string("''"); if (value.is_boolean()) return value.get() ? 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)); } 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))) throw SysError("unable to initialize seccomp mode 2"); Finally cleanup([&]() { seccomp_release(ctx); }); if (settings.thisSystem == "x86_64-linux" && seccomp_arch_add(ctx, SCMP_ARCH_X86) != 0) throw SysError("unable to add 32-bit seccomp architecture"); if (settings.thisSystem == "x86_64-linux" && seccomp_arch_add(ctx, SCMP_ARCH_X32) != 0) throw SysError("unable to add X32 seccomp architecture"); if (settings.thisSystem == "aarch64-linux" && seccomp_arch_add(ctx, SCMP_ARCH_ARM) != 0) printError("unsable 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") netrcData = readFile(settings.netrcFile); } catch (SysError &) { } #if __linux__ if (useChroot) { userNamespaceSync.writeSide = -1; if (drainFD(userNamespaceSync.readSide.get()) != "1") throw Error("user namespace initialisation failed"); userNamespaceSync.readSide = -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; strcpy(ifr.ifr_name, "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(0, "/", 0, MS_REC|MS_PRIVATE, 0) == -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(), 0, MS_BIND, 0) == -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 (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"); ss.push_back("/etc/nsswitch.conf"); 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) { debug(format("bind mounting '%1%' to '%2%'") % source % target); struct stat st; if (stat(source.c_str(), &st) == -1) { if (optional && errno == ENOENT) return; else 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, 0) == -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, 0) == -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")) { 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") && !strcmp(utsbuf.machine, "x86_64")))) { 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()) { ; } #if __APPLE__ else if (getEnv("_NIX_TEST_NO_SANDBOX") == "") { /* This has to appear before import statements. */ std::string sandboxProfile = "(version 1)\n"; if (useChroot) { /* Lots and lots and lots of file functions freak out if they can't stat their full ancestry */ PathSet ancestry; /* We build the ancestry before adding all inputPaths to the store because we know they'll all have the same parents (the store), and there might be lots of inputs. This isn't particularly efficient... I doubt it'll be a bottleneck in practice */ for (auto & i : dirsInChroot) { Path cur = i.first; while (cur.compare("/") != 0) { cur = dirOf(cur); ancestry.insert(cur); } } /* And we want the store in there regardless of how empty dirsInChroot. We include the innermost path component this time, since it's typically /nix/store and we care about that. */ Path cur = worker.store.storeDir; while (cur.compare("/") != 0) { ancestry.insert(cur); cur = dirOf(cur); } /* Add all our input paths to the chroot */ for (auto & i : inputPaths) dirsInChroot[i] = i; /* Violations will go to the syslog if you set this. Unfortunately the destination does not appear to be configurable */ if (settings.darwinLogSandboxViolations) { sandboxProfile += "(deny default)\n"; } else { sandboxProfile += "(deny default (with no-log))\n"; } sandboxProfile += "(import \"sandbox-defaults.sb\")\n"; if (fixedOutput) sandboxProfile += "(import \"sandbox-network.sb\")\n"; /* Our rwx outputs */ sandboxProfile += "(allow file-read* file-write* process-exec\n"; for (auto & i : missingPaths) { sandboxProfile += (format("\t(subpath \"%1%\")\n") % i.c_str()).str(); } sandboxProfile += ")\n"; /* Our inputs (transitive dependencies and any impurities computed above) without file-write* allowed, access() incorrectly returns EPERM */ sandboxProfile += "(allow file-read* file-write* process-exec\n"; for (auto & i : dirsInChroot) { if (i.first != i.second.source) throw Error(format( "can't map '%1%' to '%2%': mismatched impure paths not supported on Darwin") % i.first % i.second.source); string path = i.first; struct stat st; if (lstat(path.c_str(), &st)) { if (i.second.optional && errno == ENOENT) continue; throw SysError(format("getting attributes of path '%1%'") % path); } if (S_ISDIR(st.st_mode)) sandboxProfile += (format("\t(subpath \"%1%\")\n") % path).str(); else sandboxProfile += (format("\t(literal \"%1%\")\n") % path).str(); } sandboxProfile += ")\n"; /* Allow file-read* on full directory hierarchy to self. Allows realpath() */ sandboxProfile += "(allow file-read*\n"; for (auto & i : ancestry) { sandboxProfile += (format("\t(literal \"%1%\")\n") % i.c_str()).str(); } sandboxProfile += ")\n"; sandboxProfile += additionalSandboxProfile; } else sandboxProfile += "(import \"sandbox-minimal.sb\")\n"; debug("Generated sandbox profile:"); debug(sandboxProfile); Path sandboxFile = tmpDir + "/.sandbox.sb"; writeFile(sandboxFile, sandboxProfile); bool allowLocalNetworking = getBoolAttr("__darwinAllowLocalNetworking"); /* The tmpDir in scope points at the temporary build directory for our derivation. Some packages try different mechanisms to find temporary directories, so we want to open up a broader place for them to dump their files, if needed. */ Path globalTmpDir = canonPath(getEnv("TMPDIR", "/tmp"), true); /* They don't like trailing slashes on subpath directives */ if (globalTmpDir.back() == '/') globalTmpDir.pop_back(); builder = "/usr/bin/sandbox-exec"; args.push_back("sandbox-exec"); args.push_back("-f"); args.push_back(sandboxFile); args.push_back("-D"); args.push_back("_GLOBAL_TMP_DIR=" + globalTmpDir); args.push_back("-D"); args.push_back("IMPORT_DIR=" + settings.nixDataDir + "/nix/sandbox/"); if (allowLocalNetworking) { args.push_back("-D"); args.push_back(string("_ALLOW_LOCAL_NETWORKING=1")); } args.push_back(drv->builder); } #endif else { builder = drv->builder.c_str(); 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, string("\1\n")); /* Execute the program. This should not return. */ if (drv->isBuiltin()) { try { logger = makeJSONLogger(*logger); 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%'") % string(drv->builder, 8)); _exit(0); } catch (std::exception & e) { writeFull(STDERR_FILENO, "error: " + 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: " + 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; } ValidPathInfos 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 runDiffHook = settings.runDiffHook; bool keepPreviousRound = settings.keepFailed || 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); } else { Path redirected = redirectedOutputs[path]; if (buildMode == bmRepair && redirectedBadOutputs.find(path) != redirectedBadOutputs.end() && pathExists(redirected)) replaceValidPath(path, redirected); if (buildMode == bmCheck && redirected != "") 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))) || (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()) { printError(format("warning: rewriting hashes in '%1%'; cross fingers") % path); /* 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(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. */ delayedException = std::make_exception_ptr( BuildError("fixed-output derivation produced path '%s' with %s hash '%s' instead of the expected hash '%s'", dest, printHashType(h.type), printHash16or32(h2), printHash16or32(h))); 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. */ debug("scanning for references inside '%1%'", 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) { if (settings.keepFailed) { Path dst = worker.store.toRealPath(path + checkSuffix); deletePath(dst); if (rename(actualPath.c_str(), dst.c_str())) throw SysError(format("renaming '%1%' to '%2%'") % actualPath % dst); throw Error(format("derivation '%1%' may not be deterministic: output '%2%' differs from '%3%'") % drvPath % path % dst); } else throw Error(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) { PathSet::iterator j = references.find(i); if (j == references.end()) debug(format("unreferenced input: '%1%'") % i); else debug(format("referenced input: '%1%'") % i); } /* Enforce `allowedReferences' and friends. */ auto checkRefs = [&](const string & attrName, bool allowed, bool recursive) { auto value = getStringsAttr(attrName); if (!value) return; PathSet spec = parseReferenceSpecifiers(worker.store, *drv, *value); PathSet used; if (recursive) { /* Our requisites are the union of the closures of our references. */ for (auto & i : references) /* Don't call computeFSClosure on ourselves. */ if (path != i) worker.store.computeFSClosure(i, used); } else used = references; PathSet badPaths; for (auto & i : used) if (allowed) { if (spec.find(i) == spec.end()) badPaths.insert(i); } else { if (spec.find(i) != spec.end()) badPaths.insert(i); } if (!badPaths.empty()) { string badPathsStr; for (auto & i : badPaths) { badPathsStr += "\n\t"; badPathsStr += i; } throw BuildError(format("output '%1%' is not allowed to refer to the following paths:%2%") % actualPath % badPathsStr); } }; checkRefs("allowedReferences", true, false); checkRefs("allowedRequisites", true, true); checkRefs("disallowedReferences", false, false); checkRefs("disallowedRequisites", false, true); 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.push_back(info); } if (buildMode == bmCheck) return; /* 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->path + checkSuffix; bool prevExists = keepPreviousRound && pathExists(prev); auto msg = prevExists ? fmt("output '%1%' of '%2%' differs from '%3%' from previous round", i->path, drvPath, prev) : fmt("output '%1%' of '%2%' differs from previous round", i->path, drvPath); auto diffHook = settings.diffHook; if (prevExists && diffHook != "" && runDiffHook) { try { auto diff = runProgram(diffHook, true, {prev, i->path}); if (diff != "") printError(chomp(diff)); } catch (Error & error) { printError("diff hook execution failed: %s", error.what()); } } if (settings.enforceDeterminism) throw NotDeterministic(msg); printError(msg); 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())) 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. */ worker.store.registerValidPaths(infos); /* 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); } Path DerivationGoal::openLogFile() { logSize = 0; if (!settings.keepLog) return ""; string baseName = baseNameOf(drvPath); /* Create a log file. */ Path dir = fmt("%s/%s/%s/", worker.store.logDir, worker.store.drvsLogDir, string(baseName, 0, 2)); createDirs(dir); Path logFileName = fmt("%s/%s%s", dir, string(baseName, 2), settings.compressLog ? ".bz2" : ""); fdLogFile = 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(fdLogFile.get()); if (settings.compressLog) logSink = std::shared_ptr(makeCompressionSink("bzip2", *logFileSink)); else logSink = logFileSink; return logFileName; } void DerivationGoal::closeLogFile() { auto logSink2 = std::dynamic_pointer_cast(logSink); if (logSink2) logSink2->finish(); if (logFileSink) logFileSink->flush(); logSink = logFileSink = 0; fdLogFile = -1; } void DerivationGoal::deleteTmpDir(bool force) { if (tmpDir != "") { /* Don't keep temporary directories for builtins because they might have privileged stuff (like a copy of netrc). */ if (settings.keepFailed && !force && !drv->isBuiltin()) { printError( format("note: keeping build directory '%2%'") % drvPath % tmpDir); chmod(tmpDir.c_str(), 0755); } else deletePath(tmpDir); tmpDir = ""; } } void DerivationGoal::handleChildOutput(int fd, const string & data) { if ((hook && fd == hook->builderOut.readSide.get()) || (!hook && fd == builderOut.readSide.get())) { logSize += data.size(); if (settings.maxLogSize && logSize > settings.maxLogSize) { printError( format("%1% killed after writing more than %2% bytes of log output") % getName() % settings.maxLogSize); 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') { handleJSONLogMessage(currentHookLine, worker.act, hook->activities, true); currentHookLine.clear(); } else currentHookLine += c; } } void DerivationGoal::handleEOF(int fd) { if (!currentLogLine.empty()) flushLine(); worker.wakeUp(shared_from_this()); } void DerivationGoal::flushLine() { if (handleJSONLogMessage(currentLogLine, *act, builderActivities, false)) ; else { if (settings.verboseBuild && (settings.printRepeatedBuilds || curRound == 1)) printError(currentLogLine); else { logTail.push_back(currentLogLine); if (logTail.size() > settings.logLines) logTail.pop_front(); } act->result(resBuildLogLine, currentLogLine); } 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) { string h1 = string(path, worker.store.storeDir.size() + 1, 32); string h2 = string(hashString(htSHA256, "rewrite:" + drvPath + ":" + path).to_string(Base32, false), 0, 32); Path p = worker.store.storeDir + "/" + h2 + 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 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++; } worker.updateProgress(); } ////////////////////////////////////////////////////////////////////// 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> subs; /* The current substituter. */ std::shared_ptr sub; /* Whether a substituter failed. */ bool substituterFailed = false; /* Path info returned by the substituter's query info operation. */ std::shared_ptr info; /* Pipe for the substituter's standard output. */ Pipe outPipe; /* The substituter thread. */ std::thread thr; std::promise 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> maintainExpectedSubstitutions, maintainRunningSubstitutions, maintainExpectedNar, maintainExpectedDownload; typedef void (SubstitutionGoal::*GoalState)(); GoalState state; public: SubstitutionGoal(const Path & storePath, Worker & worker, RepairFlag repair = NoRepair); ~SubstitutionGoal(); void timedOut() override { abort(); }; 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 string & data) override; void handleEOF(int fd) override; Path getStorePath() { return storePath; } void amDone(ExitCode result) override { Goal::amDone(result); } }; SubstitutionGoal::SubstitutionGoal(const Path & storePath, Worker & worker, RepairFlag repair) : Goal(worker) , repair(repair) { this->storePath = storePath; state = &SubstitutionGoal::init; name = (format("substitution of '%1%'") % storePath).str(); trace("created"); maintainExpectedSubstitutions = std::make_unique>(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 && 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>(); tryNext(); } void SubstitutionGoal::tryNext() { trace("trying next substituter"); if (subs.size() == 0) { /* None left. Terminate this goal and let someone else deal with it. */ debug(format("path '%1%' is required, but there is no substituter that can build it") % storePath); /* 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++; worker.updateProgress(); } 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) { printError(e.what()); tryNext(); return; } throw; } /* Update the total expected download size. */ auto narInfo = std::dynamic_pointer_cast(info); maintainExpectedNar = std::make_unique>(worker.expectedNarSize, info->narSize); maintainExpectedDownload = narInfo && narInfo->fileSize ? std::make_unique>(worker.expectedDownloadSize, narInfo->fileSize) : nullptr; worker.updateProgress(); /* 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())) { printError("warning: substituter '%s' does not have a valid signature for path '%s'", sub->getUri(), storePath); 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) { debug(format("some references of path '%1%' could not be realised") % storePath); 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; } /* If the store path is already locked (probably by a DerivationGoal), then put this goal to sleep. Note: we don't acquire a lock here since that breaks addToStore(), so below we handle an AlreadyLocked exception from addToStore(). The check here is just an optimisation to prevent having to redo a download due to a locked path. */ if (pathIsLockedByMe(worker.store.toRealPath(storePath))) { worker.waitForAWhile(shared_from_this()); return; } maintainRunningSubstitutions = std::make_unique>(worker.runningSubstitutions); worker.updateProgress(); outPipe.create(); promise = std::promise(); thr = std::thread([this]() { try { /* Wake up the worker loop when we're done. */ Finally updateStats([this]() { outPipe.writeSide = -1; }); Activity act(*logger, actSubstitute, Logger::Fields{storePath, sub->getUri()}); PushActivity pact(act.id); copyStorePath(ref(sub), ref(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 (AlreadyLocked & e) { /* Probably a DerivationGoal is already building this store path. Sleep for a while and try again. */ state = &SubstitutionGoal::init; worker.waitForAWhile(shared_from_this()); return; } catch (std::exception & e) { printError(e.what()); /* 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); printMsg(lvlChatty, format("substitution of path '%1%' succeeded") % storePath); maintainRunningSubstitutions.reset(); maintainExpectedSubstitutions.reset(); worker.doneSubstitutions++; if (maintainExpectedDownload) { auto fileSize = maintainExpectedDownload->delta; maintainExpectedDownload.reset(); worker.doneDownloadSize += fileSize; } worker.doneNarSize += maintainExpectedNar->delta; maintainExpectedNar.reset(); worker.updateProgress(); amDone(ecSuccess); } void SubstitutionGoal::handleChildOutput(int fd, const string & data) { } void SubstitutionGoal::handleEOF(int fd) { if (fd == outPipe.readSide.get()) worker.wakeUp(shared_from_this()); } ////////////////////////////////////////////////////////////////////// static bool working = false; Worker::Worker(LocalStore & store) : act(*logger, actRealise) , actDerivations(*logger, actBuilds) , actSubstitutions(*logger, actCopyPaths) , store(store) { /* Debugging: prevent recursive workers. */ if (working) abort(); working = true; nrLocalBuilds = 0; lastWokenUp = steady_time_point::min(); permanentFailure = false; timedOut = 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 & path, const StringSet & wantedOutputs, BuildMode buildMode) { GoalPtr goal = derivationGoals[path].lock(); if (!goal) { goal = std::make_shared(path, wantedOutputs, *this, buildMode); derivationGoals[path] = goal; wakeUp(goal); } else (dynamic_cast(goal.get()))->addWantedOutputs(wantedOutputs); return goal; } std::shared_ptr Worker::makeBasicDerivationGoal(const Path & drvPath, const BasicDerivation & drv, BuildMode buildMode) { auto goal = std::make_shared(drvPath, drv, *this, buildMode); wakeUp(goal); return goal; } GoalPtr Worker::makeSubstitutionGoal(const Path & path, RepairFlag repair) { GoalPtr goal = substitutionGoals[path].lock(); if (!goal) { goal = std::make_shared(path, *this, repair); substitutionGoals[path] = goal; wakeUp(goal); } return goal; } static void removeGoal(GoalPtr goal, WeakGoalMap & goalMap) { /* !!! inefficient */ for (WeakGoalMap::iterator i = goalMap.begin(); i != goalMap.end(); ) if (i->second.lock() == goal) { WeakGoalMap::iterator j = i; ++j; goalMap.erase(i); i = j; } else ++i; } void Worker::removeGoal(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(GoalPtr goal) { goal->trace("woken up"); addToWeakGoals(awake, goal); } unsigned Worker::getNrLocalBuilds() { return nrLocalBuilds; } void Worker::childStarted(GoalPtr goal, const set & 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(GoalPtr goal) { debug("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) { debug("wait for any goal"); addToWeakGoals(waitingForAnyGoal, goal); } void Worker::waitForAWhile(GoalPtr goal) { debug("wait for a while"); addToWeakGoals(waitingForAWhile, goal); } void Worker::run(const Goals & _topGoals) { for (auto & i : _topGoals) topGoals.insert(i); debug("entered goal loop"); while (1) { 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() { printMsg(lvlVomit, "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, (long) std::chrono::duration_cast(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()) printError("waiting for locks or build slots..."); if (lastWokenUp == steady_time_point::min() || lastWokenUp > before) lastWokenUp = before; timeout.tv_sec = std::max(1L, (long) std::chrono::duration_cast( lastWokenUp + std::chrono::seconds(settings.pollInterval) - before).count()); } else lastWokenUp = steady_time_point::min(); if (useTimeout) vomit("sleeping %d seconds", timeout.tv_sec); /* 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, 0, 0, useTimeout ? &timeout : 0) == -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); set fds2(j->fds); std::vector buffer(4096); for (auto & k : fds2) { if (FD_ISSET(k, &fds)) { ssize_t rd = read(k, buffer.data(), buffer.size()); if (rd == -1) { if (errno != EINTR) throw SysError(format("reading from %1%") % goal->getName()); } else if (rd == 0) { debug(format("%1%: got EOF") % goal->getName()); goal->handleEOF(k); j->fds.erase(k); } else { printMsg(lvlVomit, format("%1%: read %2% bytes") % goal->getName() % rd); string data((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)) { printError( format("%1% timed out after %2% seconds of silence") % goal->getName() % settings.maxSilentTime); goal->timedOut(); } else if (goal->getExitCode() == Goal::ecBusy && 0 != settings.buildTimeout && j->respectTimeouts && after - j->timeStarted >= std::chrono::seconds(settings.buildTimeout)) { printError( format("%1% timed out after %2% seconds") % goal->getName() % settings.buildTimeout); 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() { return timedOut ? 101 : (permanentFailure ? 100 : 1); } bool Worker::pathContentsGood(const Path & path) { std::map::iterator i = pathContentsGoodCache.find(path); if (i != pathContentsGoodCache.end()) return i->second; printInfo(format("checking path '%1%'...") % 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) printError(format("path '%1%' is corrupted or missing!") % path); return res; } void Worker::markContentsGood(const Path & path) { pathContentsGoodCache[path] = true; } ////////////////////////////////////////////////////////////////////// static void primeCache(Store & store, const PathSet & paths) { PathSet willBuild, willSubstitute, unknown; unsigned long long downloadSize, narSize; store.queryMissing(paths, willBuild, willSubstitute, unknown, downloadSize, narSize); } void LocalStore::buildPaths(const PathSet & drvPaths, BuildMode buildMode) { Worker worker(*this); 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, buildMode)); else goals.insert(worker.makeSubstitutionGoal(i, buildMode == bmRepair ? Repair : NoRepair)); } worker.run(goals); PathSet failed; for (auto & i : goals) { if (i->getExitCode() != Goal::ecSuccess) { DerivationGoal * i2 = dynamic_cast(i.get()); if (i2) failed.insert(i2->getDrvPath()); else failed.insert(dynamic_cast(i.get())->getStorePath()); } } if (!failed.empty()) throw Error(worker.exitStatus(), "build of %s failed", showPaths(failed)); } BuildResult LocalStore::buildDerivation(const Path & drvPath, const BasicDerivation & drv, BuildMode buildMode) { Worker worker(*this); 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}); Worker worker(*this); 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) { Worker worker(*this); 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 != "" && isValidPath(deriver)) { goals.clear(); goals.insert(worker.makeDerivationGoal(deriver, StringSet(), bmRepair)); worker.run(goals); } else throw Error(worker.exitStatus(), "cannot repair path '%s'", path); } } }