diff options
Diffstat (limited to 'src/buildenv/buildenv.cc')
| -rw-r--r-- | src/buildenv/buildenv.cc | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/src/buildenv/buildenv.cc b/src/buildenv/buildenv.cc new file mode 100644 index 000000000..f997096ed --- /dev/null +++ b/src/buildenv/buildenv.cc @@ -0,0 +1,186 @@ +#include "shared.hh" +#include <sys/stat.h> +#include <sys/types.h> +#include <fcntl.h> +#include <algorithm> + +using namespace nix; + +typedef std::map<Path,int> Priorities; + +static bool isDirectory (const Path & path) +{ + struct stat st; + if (stat(path.c_str(), &st) == -1) + throw SysError(format("getting status of ‘%1%’") % path); + return S_ISDIR(st.st_mode); +} + +static auto priorities = Priorities{}; + +static auto symlinks = 0; + +/* For each activated package, create symlinks */ +static void createLinks(const Path & srcDir, const Path & dstDir, int priority) +{ + auto srcFiles = readDirectory(srcDir); + for (const auto & ent : srcFiles) { + if (ent.name[0] == '.') + /* not matched by glob */ + continue; + const auto & srcFile = srcDir + "/" + ent.name; + auto dstFile = dstDir + "/" + ent.name; + + /* 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 (hasSuffix(srcFile, "/propagated-build-inputs") || + hasSuffix(srcFile, "/nix-support") || + hasSuffix(srcFile, "/perllocal.pod") || + hasSuffix(srcFile, "/info/dir") || + hasSuffix(srcFile, "/log")) { + continue; + } else if (isDirectory(srcFile)) { + 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 = readLink(dstFile); + if (!isDirectory(target)) + throw Error(format("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 target = readLink(dstFile); + auto prevPriority = priorities[dstFile]; + if (prevPriority == priority) + throw Error(format( + "collision between ‘%1%’ and ‘%2%’; " + "use ‘nix-env --set-flag priority NUMBER PKGNAME’ " + "to change the priority of one of the conflicting packages" + ) % srcFile % target); + if (prevPriority < priority) + continue; + if (unlink(dstFile.c_str()) == -1) + throw SysError(format("unlinking ‘%1%’") % dstFile); + } + } else if (errno != ENOENT) + throw SysError(format("getting status of ‘%1%’") % dstFile); + } + createSymlink(srcFile, dstFile); + priorities[dstFile] = priority; + symlinks++; + } +} + +typedef std::set<Path> FileProp; + +static auto done = FileProp{}; +static auto postponed = FileProp{}; + +static auto out = string{}; + +static void addPkg(const Path & pkgDir, int priority) +{ + if (done.find(pkgDir) != done.end()) + return; + done.insert(pkgDir); + createLinks(pkgDir, out, priority); + auto propagatedFN = pkgDir + "/nix-support/propagated-user-env-packages"; + auto propagated = string{}; + { + AutoCloseFD fd = open(propagatedFN.c_str(), O_RDONLY | O_CLOEXEC); + if (!fd) { + if (errno == ENOENT) + return; + throw SysError(format("opening ‘%1%’") % propagatedFN); + } + propagated = readLine(fd.get()); + } + for (const auto & p : tokenizeString<std::vector<string>>(propagated, " ")) + if (done.find(p) == done.end()) + postponed.insert(p); +} + +struct Package { + Path path; + bool active; + int priority; + Package(Path path, bool active, int priority) : path{std::move(path)}, active{active}, priority{priority} {} +}; + +typedef std::vector<Package> Packages; + +int main(int argc, char ** argv) +{ + return handleExceptions(argv[0], [&]() { + initNix(); + out = getEnv("out"); + if (mkdir(out.c_str(), 0755) == -1) + throw SysError(format("creating %1%") % out); + + /* Convert the stuff we get from the environment back into a coherent + * data type. + */ + auto pkgs = Packages{}; + auto derivations = tokenizeString<Strings>(getEnv("derivations")); + 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++); + } + + std::cerr << "created " << symlinks << " symlinks in user environment\n"; + + createSymlink(getEnv("manifest"), out + "/manifest.nix"); + }); +} + |