diff options
Diffstat (limited to 'third_party/nix/src/libstore/builtins/buildenv.cc')
-rw-r--r-- | third_party/nix/src/libstore/builtins/buildenv.cc | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/third_party/nix/src/libstore/builtins/buildenv.cc b/third_party/nix/src/libstore/builtins/buildenv.cc new file mode 100644 index 000000000000..433082a0f9de --- /dev/null +++ b/third_party/nix/src/libstore/builtins/buildenv.cc @@ -0,0 +1,240 @@ +#include <algorithm> + +#include <absl/strings/match.h> +#include <absl/strings/str_split.h> +#include <fcntl.h> +#include <glog/logging.h> +#include <sys/stat.h> +#include <sys/types.h> + +#include "libstore/builtins.hh" + +namespace nix { + +typedef std::map<Path, int> Priorities; + +// FIXME: change into local variables. + +static Priorities priorities; + +static unsigned long symlinks; + +/* For each activated package, create symlinks */ +static void createLinks(const Path& srcDir, const Path& dstDir, int priority) { + DirEntries srcFiles; + + try { + srcFiles = readDirectory(srcDir); + } catch (SysError& e) { + if (e.errNo == ENOTDIR) { + LOG(ERROR) << "warning: not including '" << srcDir + << "' in the user environment because it's not a directory"; + return; + } + throw; + } + + for (const auto& ent : srcFiles) { + if (ent.name[0] == '.') { /* not matched by glob */ + continue; + } + auto srcFile = srcDir + "/" + ent.name; + auto dstFile = dstDir + "/" + ent.name; + + struct stat srcSt; + try { + if (stat(srcFile.c_str(), &srcSt) == -1) { + throw SysError("getting status of '%1%'", srcFile); + } + } catch (SysError& e) { + if (e.errNo == ENOENT || e.errNo == ENOTDIR) { + LOG(ERROR) << "warning: skipping dangling symlink '" << dstFile << "'"; + continue; + } + throw; + } + + /* The files below are special-cased to that they don't show up + * in user profiles, either because they are useless, or + * because they would cauase pointless collisions (e.g., each + * Python package brings its own + * `$out/lib/pythonX.Y/site-packages/easy-install.pth'.) + */ + if (absl::EndsWith(srcFile, "/propagated-build-inputs") || + absl::EndsWith(srcFile, "/nix-support") || + absl::EndsWith(srcFile, "/perllocal.pod") || + absl::EndsWith(srcFile, "/info/dir") || + absl::EndsWith(srcFile, "/log")) { + continue; + + } else if (S_ISDIR(srcSt.st_mode)) { + struct stat dstSt; + auto res = lstat(dstFile.c_str(), &dstSt); + if (res == 0) { + if (S_ISDIR(dstSt.st_mode)) { + createLinks(srcFile, dstFile, priority); + continue; + } else if (S_ISLNK(dstSt.st_mode)) { + auto target = canonPath(dstFile, true); + if (!S_ISDIR(lstat(target).st_mode)) { + throw Error("collision between '%1%' and non-directory '%2%'", + srcFile, target); + } + if (unlink(dstFile.c_str()) == -1) { + throw SysError(format("unlinking '%1%'") % dstFile); + } + if (mkdir(dstFile.c_str(), 0755) == -1) { + throw SysError(format("creating directory '%1%'")); + } + createLinks(target, dstFile, priorities[dstFile]); + createLinks(srcFile, dstFile, priority); + continue; + } + } else if (errno != ENOENT) { + throw SysError(format("getting status of '%1%'") % dstFile); + } + } + + else { + struct stat dstSt; + auto res = lstat(dstFile.c_str(), &dstSt); + if (res == 0) { + if (S_ISLNK(dstSt.st_mode)) { + auto prevPriority = priorities[dstFile]; + if (prevPriority == priority) { + throw Error( + "packages '%1%' and '%2%' have the same priority %3%; " + "use 'nix-env --set-flag priority NUMBER INSTALLED_PKGNAME' " + "to change the priority of one of the conflicting packages" + " (0 being the highest priority)", + srcFile, readLink(dstFile), priority); + } + if (prevPriority < priority) { + continue; + } + if (unlink(dstFile.c_str()) == -1) { + throw SysError(format("unlinking '%1%'") % dstFile); + } + } else if (S_ISDIR(dstSt.st_mode)) { + throw Error( + "collision between non-directory '%1%' and directory '%2%'", + srcFile, dstFile); + } + } else if (errno != ENOENT) { + throw SysError(format("getting status of '%1%'") % dstFile); + } + } + + createSymlink(srcFile, dstFile); + priorities[dstFile] = priority; + symlinks++; + } +} + +using FileProp = std::set<Path>; + +static FileProp done; +static FileProp postponed = FileProp{}; + +static Path out; + +static void addPkg(const Path& pkgDir, int priority) { + if (done.count(pkgDir)) { + return; + } + done.insert(pkgDir); + createLinks(pkgDir, out, priority); + + try { + for (auto p : absl::StrSplit( + readFile(pkgDir + "/nix-support/propagated-user-env-packages"), + absl::ByAnyChar(" \n"), absl::SkipEmpty())) { + auto pkg = std::string(p); + if (!done.count(pkg)) { + postponed.insert(pkg); + } + } + } catch (SysError& e) { + if (e.errNo != ENOENT && e.errNo != ENOTDIR) { + throw; + } + } +} + +struct Package { + Path path; + bool active; + int priority; + Package(Path path, bool active, int priority) + : path{path}, active{active}, priority{priority} {} +}; + +using Packages = std::vector<Package>; + +void builtinBuildenv(const BasicDerivation& drv) { + auto getAttr = [&](const std::string& name) { + auto i = drv.env.find(name); + if (i == drv.env.end()) { + throw Error("attribute '%s' missing", name); + } + return i->second; + }; + + out = getAttr("out"); + createDirs(out); + + /* Convert the stuff we get from the environment back into a + * coherent data type. */ + Packages pkgs; + Strings derivations = absl::StrSplit( + getAttr("derivations"), absl::ByAnyChar(" \t\n\r"), absl::SkipEmpty()); + while (!derivations.empty()) { + /* !!! We're trusting the caller to structure derivations env var correctly + */ + auto active = derivations.front(); + derivations.pop_front(); + auto priority = stoi(derivations.front()); + derivations.pop_front(); + auto outputs = stoi(derivations.front()); + derivations.pop_front(); + for (auto n = 0; n < outputs; n++) { + auto path = derivations.front(); + derivations.pop_front(); + pkgs.emplace_back(path, active != "false", priority); + } + } + + /* Symlink to the packages that have been installed explicitly by the + * user. Process in priority order to reduce unnecessary + * symlink/unlink steps. + */ + std::sort(pkgs.begin(), pkgs.end(), [](const Package& a, const Package& b) { + return a.priority < b.priority || + (a.priority == b.priority && a.path < b.path); + }); + for (const auto& pkg : pkgs) { + if (pkg.active) { + addPkg(pkg.path, pkg.priority); + } + } + + /* Symlink to the packages that have been "propagated" by packages + * installed by the user (i.e., package X declares that it wants Y + * installed as well). We do these later because they have a lower + * priority in case of collisions. + */ + auto priorityCounter = 1000; + while (!postponed.empty()) { + auto pkgDirs = postponed; + postponed = FileProp{}; + for (const auto& pkgDir : pkgDirs) { + addPkg(pkgDir, priorityCounter++); + } + } + + LOG(INFO) << "created " << symlinks << " symlinks in user environment"; + + createSymlink(getAttr("manifest"), out + "/manifest.nix"); +} + +} // namespace nix |