forked from lix-project/lix
953 lines
31 KiB
C++
953 lines
31 KiB
C++
#include "derivations.hh"
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#include "globals.hh"
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#include "local-store.hh"
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#include "finally.hh"
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#include <functional>
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#include <queue>
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#include <algorithm>
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#include <regex>
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#include <random>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/statvfs.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <climits>
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namespace nix {
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static string gcLockName = "gc.lock";
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static string gcRootsDir = "gcroots";
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/* Acquire the global GC lock. This is used to prevent new Nix
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processes from starting after the temporary root files have been
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read. To be precise: when they try to create a new temporary root
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file, they will block until the garbage collector has finished /
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yielded the GC lock. */
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AutoCloseFD LocalStore::openGCLock(LockType lockType)
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{
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Path fnGCLock = (format("%1%/%2%")
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% stateDir % gcLockName).str();
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debug(format("acquiring global GC lock '%1%'") % fnGCLock);
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AutoCloseFD fdGCLock = open(fnGCLock.c_str(), O_RDWR | O_CREAT | O_CLOEXEC, 0600);
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if (!fdGCLock)
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throw SysError(format("opening global GC lock '%1%'") % fnGCLock);
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if (!lockFile(fdGCLock.get(), lockType, false)) {
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printError(format("waiting for the big garbage collector lock..."));
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lockFile(fdGCLock.get(), lockType, true);
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}
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/* !!! Restrict read permission on the GC root. Otherwise any
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process that can open the file for reading can DoS the
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collector. */
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return fdGCLock;
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}
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static void makeSymlink(const Path & link, const Path & target)
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{
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/* Create directories up to `gcRoot'. */
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createDirs(dirOf(link));
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/* Create the new symlink. */
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Path tempLink = (format("%1%.tmp-%2%-%3%")
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% link % getpid() % random()).str();
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createSymlink(target, tempLink);
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/* Atomically replace the old one. */
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if (rename(tempLink.c_str(), link.c_str()) == -1)
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throw SysError(format("cannot rename '%1%' to '%2%'")
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% tempLink % link);
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}
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void LocalStore::syncWithGC()
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{
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AutoCloseFD fdGCLock = openGCLock(ltRead);
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}
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void LocalStore::addIndirectRoot(const Path & path)
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{
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string hash = hashString(htSHA1, path).to_string(Base32, false);
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Path realRoot = canonPath((format("%1%/%2%/auto/%3%")
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% stateDir % gcRootsDir % hash).str());
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makeSymlink(realRoot, path);
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}
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Path LocalFSStore::addPermRoot(const Path & _storePath,
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const Path & _gcRoot, bool indirect, bool allowOutsideRootsDir)
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{
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Path storePath(canonPath(_storePath));
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Path gcRoot(canonPath(_gcRoot));
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assertStorePath(storePath);
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if (isInStore(gcRoot))
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throw Error(format(
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"creating a garbage collector root (%1%) in the Nix store is forbidden "
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"(are you running nix-build inside the store?)") % gcRoot);
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if (indirect) {
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/* Don't clobber the link if it already exists and doesn't
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point to the Nix store. */
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if (pathExists(gcRoot) && (!isLink(gcRoot) || !isInStore(readLink(gcRoot))))
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throw Error(format("cannot create symlink '%1%'; already exists") % gcRoot);
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makeSymlink(gcRoot, storePath);
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addIndirectRoot(gcRoot);
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}
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else {
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if (!allowOutsideRootsDir) {
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Path rootsDir = canonPath((format("%1%/%2%") % stateDir % gcRootsDir).str());
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if (string(gcRoot, 0, rootsDir.size() + 1) != rootsDir + "/")
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throw Error(format(
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"path '%1%' is not a valid garbage collector root; "
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"it's not in the directory '%2%'")
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% gcRoot % rootsDir);
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}
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if (baseNameOf(gcRoot) == baseNameOf(storePath))
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writeFile(gcRoot, "");
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else
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makeSymlink(gcRoot, storePath);
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}
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/* Check that the root can be found by the garbage collector.
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!!! This can be very slow on machines that have many roots.
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Instead of reading all the roots, it would be more efficient to
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check if the root is in a directory in or linked from the
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gcroots directory. */
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if (settings.checkRootReachability) {
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Roots roots = findRoots(false);
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if (roots[storePath].count(gcRoot) == 0)
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printError(
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format(
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"warning: '%1%' is not in a directory where the garbage collector looks for roots; "
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"therefore, '%2%' might be removed by the garbage collector")
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% gcRoot % storePath);
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}
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/* Grab the global GC root, causing us to block while a GC is in
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progress. This prevents the set of permanent roots from
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increasing while a GC is in progress. */
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syncWithGC();
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return gcRoot;
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}
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void LocalStore::addTempRoot(const Path & path)
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{
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auto state(_state.lock());
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/* Create the temporary roots file for this process. */
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if (!state->fdTempRoots) {
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while (1) {
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AutoCloseFD fdGCLock = openGCLock(ltRead);
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if (pathExists(fnTempRoots))
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/* It *must* be stale, since there can be no two
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processes with the same pid. */
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unlink(fnTempRoots.c_str());
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state->fdTempRoots = openLockFile(fnTempRoots, true);
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fdGCLock = -1;
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debug(format("acquiring read lock on '%1%'") % fnTempRoots);
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lockFile(state->fdTempRoots.get(), ltRead, true);
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/* Check whether the garbage collector didn't get in our
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way. */
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struct stat st;
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if (fstat(state->fdTempRoots.get(), &st) == -1)
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throw SysError(format("statting '%1%'") % fnTempRoots);
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if (st.st_size == 0) break;
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/* The garbage collector deleted this file before we could
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get a lock. (It won't delete the file after we get a
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lock.) Try again. */
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}
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}
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/* Upgrade the lock to a write lock. This will cause us to block
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if the garbage collector is holding our lock. */
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debug(format("acquiring write lock on '%1%'") % fnTempRoots);
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lockFile(state->fdTempRoots.get(), ltWrite, true);
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string s = path + '\0';
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writeFull(state->fdTempRoots.get(), s);
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/* Downgrade to a read lock. */
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debug(format("downgrading to read lock on '%1%'") % fnTempRoots);
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lockFile(state->fdTempRoots.get(), ltRead, true);
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}
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static std::string censored = "{censored}";
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void LocalStore::findTempRoots(FDs & fds, Roots & tempRoots, bool censor)
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{
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/* Read the `temproots' directory for per-process temporary root
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files. */
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for (auto & i : readDirectory(tempRootsDir)) {
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Path path = tempRootsDir + "/" + i.name;
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pid_t pid = std::stoi(i.name);
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debug(format("reading temporary root file '%1%'") % path);
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FDPtr fd(new AutoCloseFD(open(path.c_str(), O_CLOEXEC | O_RDWR, 0666)));
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if (!*fd) {
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/* It's okay if the file has disappeared. */
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if (errno == ENOENT) continue;
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throw SysError(format("opening temporary roots file '%1%'") % path);
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}
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/* This should work, but doesn't, for some reason. */
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//FDPtr fd(new AutoCloseFD(openLockFile(path, false)));
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//if (*fd == -1) continue;
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/* Try to acquire a write lock without blocking. This can
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only succeed if the owning process has died. In that case
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we don't care about its temporary roots. */
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if (lockFile(fd->get(), ltWrite, false)) {
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printError(format("removing stale temporary roots file '%1%'") % path);
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unlink(path.c_str());
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writeFull(fd->get(), "d");
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continue;
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}
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/* Acquire a read lock. This will prevent the owning process
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from upgrading to a write lock, therefore it will block in
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addTempRoot(). */
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debug(format("waiting for read lock on '%1%'") % path);
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lockFile(fd->get(), ltRead, true);
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/* Read the entire file. */
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string contents = readFile(fd->get());
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/* Extract the roots. */
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string::size_type pos = 0, end;
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while ((end = contents.find((char) 0, pos)) != string::npos) {
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Path root(contents, pos, end - pos);
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debug("got temporary root '%s'", root);
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assertStorePath(root);
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tempRoots[root].emplace(censor ? censored : fmt("{temp:%d}", pid));
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pos = end + 1;
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}
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fds.push_back(fd); /* keep open */
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}
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}
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void LocalStore::findRoots(const Path & path, unsigned char type, Roots & roots)
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{
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auto foundRoot = [&](const Path & path, const Path & target) {
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Path storePath = toStorePath(target);
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if (isStorePath(storePath) && isValidPath(storePath))
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roots[storePath].emplace(path);
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else
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printInfo(format("skipping invalid root from '%1%' to '%2%'") % path % storePath);
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};
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try {
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if (type == DT_UNKNOWN)
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type = getFileType(path);
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if (type == DT_DIR) {
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for (auto & i : readDirectory(path))
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findRoots(path + "/" + i.name, i.type, roots);
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}
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else if (type == DT_LNK) {
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Path target = readLink(path);
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if (isInStore(target))
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foundRoot(path, target);
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/* Handle indirect roots. */
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else {
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target = absPath(target, dirOf(path));
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if (!pathExists(target)) {
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if (isInDir(path, stateDir + "/" + gcRootsDir + "/auto")) {
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printInfo(format("removing stale link from '%1%' to '%2%'") % path % target);
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unlink(path.c_str());
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}
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} else {
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struct stat st2 = lstat(target);
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if (!S_ISLNK(st2.st_mode)) return;
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Path target2 = readLink(target);
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if (isInStore(target2)) foundRoot(target, target2);
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}
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}
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}
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else if (type == DT_REG) {
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Path storePath = storeDir + "/" + baseNameOf(path);
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if (isStorePath(storePath) && isValidPath(storePath))
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roots[storePath].emplace(path);
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}
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}
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catch (SysError & e) {
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/* We only ignore permanent failures. */
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if (e.errNo == EACCES || e.errNo == ENOENT || e.errNo == ENOTDIR)
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printInfo(format("cannot read potential root '%1%'") % path);
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else
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throw;
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}
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}
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void LocalStore::findRootsNoTemp(Roots & roots, bool censor)
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{
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/* Process direct roots in {gcroots,profiles}. */
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findRoots(stateDir + "/" + gcRootsDir, DT_UNKNOWN, roots);
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findRoots(stateDir + "/profiles", DT_UNKNOWN, roots);
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/* Add additional roots returned by different platforms-specific
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heuristics. This is typically used to add running programs to
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the set of roots (to prevent them from being garbage collected). */
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findRuntimeRoots(roots, censor);
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}
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Roots LocalStore::findRoots(bool censor)
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{
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Roots roots;
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findRootsNoTemp(roots, censor);
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FDs fds;
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findTempRoots(fds, roots, censor);
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return roots;
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}
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static void readProcLink(const string & file, Roots & roots)
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{
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/* 64 is the starting buffer size gnu readlink uses... */
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auto bufsiz = ssize_t{64};
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try_again:
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char buf[bufsiz];
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auto res = readlink(file.c_str(), buf, bufsiz);
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if (res == -1) {
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if (errno == ENOENT || errno == EACCES || errno == ESRCH)
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return;
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throw SysError("reading symlink");
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}
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if (res == bufsiz) {
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if (SSIZE_MAX / 2 < bufsiz)
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throw Error("stupidly long symlink");
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bufsiz *= 2;
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goto try_again;
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}
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if (res > 0 && buf[0] == '/')
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roots[std::string(static_cast<char *>(buf), res)]
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.emplace(file);
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}
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static string quoteRegexChars(const string & raw)
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{
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static auto specialRegex = std::regex(R"([.^$\\*+?()\[\]{}|])");
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return std::regex_replace(raw, specialRegex, R"(\$&)");
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}
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static void readFileRoots(const char * path, Roots & roots)
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{
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try {
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roots[readFile(path)].emplace(path);
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} catch (SysError & e) {
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if (e.errNo != ENOENT && e.errNo != EACCES)
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throw;
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}
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}
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void LocalStore::findRuntimeRoots(Roots & roots, bool censor)
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{
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Roots unchecked;
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auto procDir = AutoCloseDir{opendir("/proc")};
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if (procDir) {
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struct dirent * ent;
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auto digitsRegex = std::regex(R"(^\d+$)");
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auto mapRegex = std::regex(R"(^\s*\S+\s+\S+\s+\S+\s+\S+\s+\S+\s+(/\S+)\s*$)");
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auto storePathRegex = std::regex(quoteRegexChars(storeDir) + R"(/[0-9a-z]+[0-9a-zA-Z\+\-\._\?=]*)");
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while (errno = 0, ent = readdir(procDir.get())) {
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checkInterrupt();
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if (std::regex_match(ent->d_name, digitsRegex)) {
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readProcLink(fmt("/proc/%s/exe" ,ent->d_name), unchecked);
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readProcLink(fmt("/proc/%s/cwd", ent->d_name), unchecked);
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auto fdStr = fmt("/proc/%s/fd", ent->d_name);
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auto fdDir = AutoCloseDir(opendir(fdStr.c_str()));
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if (!fdDir) {
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if (errno == ENOENT || errno == EACCES)
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continue;
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throw SysError(format("opening %1%") % fdStr);
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}
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struct dirent * fd_ent;
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while (errno = 0, fd_ent = readdir(fdDir.get())) {
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if (fd_ent->d_name[0] != '.')
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readProcLink(fmt("%s/%s", fdStr, fd_ent->d_name), unchecked);
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}
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if (errno) {
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if (errno == ESRCH)
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continue;
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throw SysError(format("iterating /proc/%1%/fd") % ent->d_name);
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}
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fdDir.reset();
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try {
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auto mapFile = fmt("/proc/%s/maps", ent->d_name);
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auto mapLines = tokenizeString<std::vector<string>>(readFile(mapFile, true), "\n");
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for (const auto & line : mapLines) {
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auto match = std::smatch{};
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if (std::regex_match(line, match, mapRegex))
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unchecked[match[1]].emplace(mapFile);
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}
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auto envFile = fmt("/proc/%s/environ", ent->d_name);
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auto envString = readFile(envFile, true);
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auto env_end = std::sregex_iterator{};
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for (auto i = std::sregex_iterator{envString.begin(), envString.end(), storePathRegex}; i != env_end; ++i)
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unchecked[i->str()].emplace(envFile);
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} catch (SysError & e) {
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if (errno == ENOENT || errno == EACCES || errno == ESRCH)
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continue;
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throw;
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}
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}
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}
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if (errno)
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throw SysError("iterating /proc");
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}
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#if !defined(__linux__)
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// lsof is really slow on OS X. This actually causes the gc-concurrent.sh test to fail.
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// See: https://github.com/NixOS/nix/issues/3011
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// Because of this we disable lsof when running the tests.
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if (getEnv("_NIX_TEST_NO_LSOF") == "") {
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try {
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std::regex lsofRegex(R"(^n(/.*)$)");
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auto lsofLines =
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tokenizeString<std::vector<string>>(runProgram(LSOF, true, { "-n", "-w", "-F", "n" }), "\n");
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for (const auto & line : lsofLines) {
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std::smatch match;
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if (std::regex_match(line, match, lsofRegex))
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unchecked[match[1]].emplace("{lsof}");
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}
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} catch (ExecError & e) {
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/* lsof not installed, lsof failed */
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}
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}
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#endif
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#if defined(__linux__)
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readFileRoots("/proc/sys/kernel/modprobe", unchecked);
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readFileRoots("/proc/sys/kernel/fbsplash", unchecked);
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readFileRoots("/proc/sys/kernel/poweroff_cmd", unchecked);
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#endif
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for (auto & [target, links] : unchecked) {
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if (isInStore(target)) {
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Path path = toStorePath(target);
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if (isStorePath(path) && isValidPath(path)) {
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debug(format("got additional root '%1%'") % path);
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if (censor)
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roots[path].insert(censored);
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else
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roots[path].insert(links.begin(), links.end());
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}
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}
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}
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}
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struct GCLimitReached { };
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struct LocalStore::GCState
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{
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GCOptions options;
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GCResults & results;
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PathSet roots;
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PathSet tempRoots;
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PathSet dead;
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PathSet alive;
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bool gcKeepOutputs;
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bool gcKeepDerivations;
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unsigned long long bytesInvalidated;
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bool moveToTrash = true;
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bool shouldDelete;
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GCState(GCResults & results_) : results(results_), bytesInvalidated(0) { }
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};
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bool LocalStore::isActiveTempFile(const GCState & state,
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const Path & path, const string & suffix)
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{
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return hasSuffix(path, suffix)
|
||
&& state.tempRoots.find(string(path, 0, path.size() - suffix.size())) != state.tempRoots.end();
|
||
}
|
||
|
||
|
||
void LocalStore::deleteGarbage(GCState & state, const Path & path)
|
||
{
|
||
unsigned long long bytesFreed;
|
||
deletePath(path, bytesFreed);
|
||
state.results.bytesFreed += bytesFreed;
|
||
}
|
||
|
||
|
||
void LocalStore::deletePathRecursive(GCState & state, const Path & path)
|
||
{
|
||
checkInterrupt();
|
||
|
||
unsigned long long size = 0;
|
||
|
||
if (isStorePath(path) && isValidPath(path)) {
|
||
PathSet referrers;
|
||
queryReferrers(path, referrers);
|
||
for (auto & i : referrers)
|
||
if (i != path) deletePathRecursive(state, i);
|
||
size = queryPathInfo(path)->narSize;
|
||
invalidatePathChecked(path);
|
||
}
|
||
|
||
Path realPath = realStoreDir + "/" + baseNameOf(path);
|
||
|
||
struct stat st;
|
||
if (lstat(realPath.c_str(), &st)) {
|
||
if (errno == ENOENT) return;
|
||
throw SysError(format("getting status of %1%") % realPath);
|
||
}
|
||
|
||
printInfo(format("deleting '%1%'") % path);
|
||
|
||
state.results.paths.insert(path);
|
||
|
||
/* If the path is not a regular file or symlink, move it to the
|
||
trash directory. The move is to ensure that later (when we're
|
||
not holding the global GC lock) we can delete the path without
|
||
being afraid that the path has become alive again. Otherwise
|
||
delete it right away. */
|
||
if (state.moveToTrash && S_ISDIR(st.st_mode)) {
|
||
// Estimate the amount freed using the narSize field. FIXME:
|
||
// if the path was not valid, need to determine the actual
|
||
// size.
|
||
try {
|
||
if (chmod(realPath.c_str(), st.st_mode | S_IWUSR) == -1)
|
||
throw SysError(format("making '%1%' writable") % realPath);
|
||
Path tmp = trashDir + "/" + baseNameOf(path);
|
||
if (rename(realPath.c_str(), tmp.c_str()))
|
||
throw SysError(format("unable to rename '%1%' to '%2%'") % realPath % tmp);
|
||
state.bytesInvalidated += size;
|
||
} catch (SysError & e) {
|
||
if (e.errNo == ENOSPC) {
|
||
printInfo(format("note: can't create move '%1%': %2%") % realPath % e.msg());
|
||
deleteGarbage(state, realPath);
|
||
}
|
||
}
|
||
} else
|
||
deleteGarbage(state, realPath);
|
||
|
||
if (state.results.bytesFreed + state.bytesInvalidated > state.options.maxFreed) {
|
||
printInfo(format("deleted or invalidated more than %1% bytes; stopping") % state.options.maxFreed);
|
||
throw GCLimitReached();
|
||
}
|
||
}
|
||
|
||
|
||
bool LocalStore::canReachRoot(GCState & state, PathSet & visited, const Path & path)
|
||
{
|
||
if (visited.count(path)) return false;
|
||
|
||
if (state.alive.count(path)) return true;
|
||
|
||
if (state.dead.count(path)) return false;
|
||
|
||
if (state.roots.count(path)) {
|
||
debug(format("cannot delete '%1%' because it's a root") % path);
|
||
state.alive.insert(path);
|
||
return true;
|
||
}
|
||
|
||
visited.insert(path);
|
||
|
||
if (!isStorePath(path) || !isValidPath(path)) return false;
|
||
|
||
PathSet incoming;
|
||
|
||
/* Don't delete this path if any of its referrers are alive. */
|
||
queryReferrers(path, incoming);
|
||
|
||
/* If keep-derivations is set and this is a derivation, then
|
||
don't delete the derivation if any of the outputs are alive. */
|
||
if (state.gcKeepDerivations && isDerivation(path)) {
|
||
PathSet outputs = queryDerivationOutputs(path);
|
||
for (auto & i : outputs)
|
||
if (isValidPath(i) && queryPathInfo(i)->deriver == path)
|
||
incoming.insert(i);
|
||
}
|
||
|
||
/* If keep-outputs is set, then don't delete this path if there
|
||
are derivers of this path that are not garbage. */
|
||
if (state.gcKeepOutputs) {
|
||
PathSet derivers = queryValidDerivers(path);
|
||
for (auto & i : derivers)
|
||
incoming.insert(i);
|
||
}
|
||
|
||
for (auto & i : incoming)
|
||
if (i != path)
|
||
if (canReachRoot(state, visited, i)) {
|
||
state.alive.insert(path);
|
||
return true;
|
||
}
|
||
|
||
return false;
|
||
}
|
||
|
||
|
||
void LocalStore::tryToDelete(GCState & state, const Path & path)
|
||
{
|
||
checkInterrupt();
|
||
|
||
auto realPath = realStoreDir + "/" + baseNameOf(path);
|
||
if (realPath == linksDir || realPath == trashDir) return;
|
||
|
||
//Activity act(*logger, lvlDebug, format("considering whether to delete '%1%'") % path);
|
||
|
||
if (!isStorePath(path) || !isValidPath(path)) {
|
||
/* A lock file belonging to a path that we're building right
|
||
now isn't garbage. */
|
||
if (isActiveTempFile(state, path, ".lock")) return;
|
||
|
||
/* Don't delete .chroot directories for derivations that are
|
||
currently being built. */
|
||
if (isActiveTempFile(state, path, ".chroot")) return;
|
||
|
||
/* Don't delete .check directories for derivations that are
|
||
currently being built, because we may need to run
|
||
diff-hook. */
|
||
if (isActiveTempFile(state, path, ".check")) return;
|
||
}
|
||
|
||
PathSet visited;
|
||
|
||
if (canReachRoot(state, visited, path)) {
|
||
debug(format("cannot delete '%1%' because it's still reachable") % path);
|
||
} else {
|
||
/* No path we visited was a root, so everything is garbage.
|
||
But we only delete ‘path’ and its referrers here so that
|
||
‘nix-store --delete’ doesn't have the unexpected effect of
|
||
recursing into derivations and outputs. */
|
||
state.dead.insert(visited.begin(), visited.end());
|
||
if (state.shouldDelete)
|
||
deletePathRecursive(state, path);
|
||
}
|
||
}
|
||
|
||
|
||
/* Unlink all files in /nix/store/.links that have a link count of 1,
|
||
which indicates that there are no other links and so they can be
|
||
safely deleted. FIXME: race condition with optimisePath(): we
|
||
might see a link count of 1 just before optimisePath() increases
|
||
the link count. */
|
||
void LocalStore::removeUnusedLinks(const GCState & state)
|
||
{
|
||
AutoCloseDir dir(opendir(linksDir.c_str()));
|
||
if (!dir) throw SysError(format("opening directory '%1%'") % linksDir);
|
||
|
||
long long actualSize = 0, unsharedSize = 0;
|
||
|
||
struct dirent * dirent;
|
||
while (errno = 0, dirent = readdir(dir.get())) {
|
||
checkInterrupt();
|
||
string name = dirent->d_name;
|
||
if (name == "." || name == "..") continue;
|
||
Path path = linksDir + "/" + name;
|
||
|
||
struct stat st;
|
||
if (lstat(path.c_str(), &st) == -1)
|
||
throw SysError(format("statting '%1%'") % path);
|
||
|
||
if (st.st_nlink != 1) {
|
||
actualSize += st.st_size;
|
||
unsharedSize += (st.st_nlink - 1) * st.st_size;
|
||
continue;
|
||
}
|
||
|
||
printMsg(lvlTalkative, format("deleting unused link '%1%'") % path);
|
||
|
||
if (unlink(path.c_str()) == -1)
|
||
throw SysError(format("deleting '%1%'") % path);
|
||
|
||
state.results.bytesFreed += st.st_size;
|
||
}
|
||
|
||
struct stat st;
|
||
if (stat(linksDir.c_str(), &st) == -1)
|
||
throw SysError(format("statting '%1%'") % linksDir);
|
||
long long overhead = st.st_blocks * 512ULL;
|
||
|
||
printInfo(format("note: currently hard linking saves %.2f MiB")
|
||
% ((unsharedSize - actualSize - overhead) / (1024.0 * 1024.0)));
|
||
}
|
||
|
||
|
||
void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
|
||
{
|
||
GCState state(results);
|
||
state.options = options;
|
||
state.gcKeepOutputs = settings.gcKeepOutputs;
|
||
state.gcKeepDerivations = settings.gcKeepDerivations;
|
||
|
||
/* Using `--ignore-liveness' with `--delete' can have unintended
|
||
consequences if `keep-outputs' or `keep-derivations' are true
|
||
(the garbage collector will recurse into deleting the outputs
|
||
or derivers, respectively). So disable them. */
|
||
if (options.action == GCOptions::gcDeleteSpecific && options.ignoreLiveness) {
|
||
state.gcKeepOutputs = false;
|
||
state.gcKeepDerivations = false;
|
||
}
|
||
|
||
state.shouldDelete = options.action == GCOptions::gcDeleteDead || options.action == GCOptions::gcDeleteSpecific;
|
||
|
||
if (state.shouldDelete)
|
||
deletePath(reservedPath);
|
||
|
||
/* Acquire the global GC root. This prevents
|
||
a) New roots from being added.
|
||
b) Processes from creating new temporary root files. */
|
||
AutoCloseFD fdGCLock = openGCLock(ltWrite);
|
||
|
||
/* Find the roots. Since we've grabbed the GC lock, the set of
|
||
permanent roots cannot increase now. */
|
||
printError(format("finding garbage collector roots..."));
|
||
Roots rootMap;
|
||
if (!options.ignoreLiveness)
|
||
findRootsNoTemp(rootMap, true);
|
||
|
||
for (auto & i : rootMap) state.roots.insert(i.first);
|
||
|
||
/* Read the temporary roots. This acquires read locks on all
|
||
per-process temporary root files. So after this point no paths
|
||
can be added to the set of temporary roots. */
|
||
FDs fds;
|
||
Roots tempRoots;
|
||
findTempRoots(fds, tempRoots, true);
|
||
for (auto & root : tempRoots)
|
||
state.tempRoots.insert(root.first);
|
||
state.roots.insert(state.tempRoots.begin(), state.tempRoots.end());
|
||
|
||
/* After this point the set of roots or temporary roots cannot
|
||
increase, since we hold locks on everything. So everything
|
||
that is not reachable from `roots' is garbage. */
|
||
|
||
if (state.shouldDelete) {
|
||
if (pathExists(trashDir)) deleteGarbage(state, trashDir);
|
||
try {
|
||
createDirs(trashDir);
|
||
} catch (SysError & e) {
|
||
if (e.errNo == ENOSPC) {
|
||
printInfo(format("note: can't create trash directory: %1%") % e.msg());
|
||
state.moveToTrash = false;
|
||
}
|
||
}
|
||
}
|
||
|
||
/* Now either delete all garbage paths, or just the specified
|
||
paths (for gcDeleteSpecific). */
|
||
|
||
if (options.action == GCOptions::gcDeleteSpecific) {
|
||
|
||
for (auto & i : options.pathsToDelete) {
|
||
assertStorePath(i);
|
||
tryToDelete(state, i);
|
||
if (state.dead.find(i) == state.dead.end())
|
||
throw Error(format(
|
||
"cannot delete path '%1%' since it is still alive. "
|
||
"To find out why use: "
|
||
"nix-store --query --roots"
|
||
) % i);
|
||
}
|
||
|
||
} else if (options.maxFreed > 0) {
|
||
|
||
if (state.shouldDelete)
|
||
printError(format("deleting garbage..."));
|
||
else
|
||
printError(format("determining live/dead paths..."));
|
||
|
||
try {
|
||
|
||
AutoCloseDir dir(opendir(realStoreDir.c_str()));
|
||
if (!dir) throw SysError(format("opening directory '%1%'") % realStoreDir);
|
||
|
||
/* Read the store and immediately delete all paths that
|
||
aren't valid. When using --max-freed etc., deleting
|
||
invalid paths is preferred over deleting unreachable
|
||
paths, since unreachable paths could become reachable
|
||
again. We don't use readDirectory() here so that GCing
|
||
can start faster. */
|
||
Paths entries;
|
||
struct dirent * dirent;
|
||
while (errno = 0, dirent = readdir(dir.get())) {
|
||
checkInterrupt();
|
||
string name = dirent->d_name;
|
||
if (name == "." || name == "..") continue;
|
||
Path path = storeDir + "/" + name;
|
||
if (isStorePath(path) && isValidPath(path))
|
||
entries.push_back(path);
|
||
else
|
||
tryToDelete(state, path);
|
||
}
|
||
|
||
dir.reset();
|
||
|
||
/* Now delete the unreachable valid paths. Randomise the
|
||
order in which we delete entries to make the collector
|
||
less biased towards deleting paths that come
|
||
alphabetically first (e.g. /nix/store/000...). This
|
||
matters when using --max-freed etc. */
|
||
vector<Path> entries_(entries.begin(), entries.end());
|
||
std::mt19937 gen(1);
|
||
std::shuffle(entries_.begin(), entries_.end(), gen);
|
||
|
||
for (auto & i : entries_)
|
||
tryToDelete(state, i);
|
||
|
||
} catch (GCLimitReached & e) {
|
||
}
|
||
}
|
||
|
||
if (state.options.action == GCOptions::gcReturnLive) {
|
||
state.results.paths = state.alive;
|
||
return;
|
||
}
|
||
|
||
if (state.options.action == GCOptions::gcReturnDead) {
|
||
state.results.paths = state.dead;
|
||
return;
|
||
}
|
||
|
||
/* Allow other processes to add to the store from here on. */
|
||
fdGCLock = -1;
|
||
fds.clear();
|
||
|
||
/* Delete the trash directory. */
|
||
printInfo(format("deleting '%1%'") % trashDir);
|
||
deleteGarbage(state, trashDir);
|
||
|
||
/* Clean up the links directory. */
|
||
if (options.action == GCOptions::gcDeleteDead || options.action == GCOptions::gcDeleteSpecific) {
|
||
printError(format("deleting unused links..."));
|
||
removeUnusedLinks(state);
|
||
}
|
||
|
||
/* While we're at it, vacuum the database. */
|
||
//if (options.action == GCOptions::gcDeleteDead) vacuumDB();
|
||
}
|
||
|
||
|
||
void LocalStore::autoGC(bool sync)
|
||
{
|
||
static auto fakeFreeSpaceFile = getEnv("_NIX_TEST_FREE_SPACE_FILE", "");
|
||
|
||
auto getAvail = [this]() -> uint64_t {
|
||
if (!fakeFreeSpaceFile.empty())
|
||
return std::stoll(readFile(fakeFreeSpaceFile));
|
||
|
||
struct statvfs st;
|
||
if (statvfs(realStoreDir.c_str(), &st))
|
||
throw SysError("getting filesystem info about '%s'", realStoreDir);
|
||
|
||
return (uint64_t) st.f_bavail * st.f_bsize;
|
||
};
|
||
|
||
std::shared_future<void> future;
|
||
|
||
{
|
||
auto state(_state.lock());
|
||
|
||
if (state->gcRunning) {
|
||
future = state->gcFuture;
|
||
debug("waiting for auto-GC to finish");
|
||
goto sync;
|
||
}
|
||
|
||
auto now = std::chrono::steady_clock::now();
|
||
|
||
if (now < state->lastGCCheck + std::chrono::seconds(settings.minFreeCheckInterval)) return;
|
||
|
||
auto avail = getAvail();
|
||
|
||
state->lastGCCheck = now;
|
||
|
||
if (avail >= settings.minFree || avail >= settings.maxFree) return;
|
||
|
||
if (avail > state->availAfterGC * 0.97) return;
|
||
|
||
state->gcRunning = true;
|
||
|
||
std::promise<void> promise;
|
||
future = state->gcFuture = promise.get_future().share();
|
||
|
||
std::thread([promise{std::move(promise)}, this, avail, getAvail]() mutable {
|
||
|
||
try {
|
||
|
||
/* Wake up any threads waiting for the auto-GC to finish. */
|
||
Finally wakeup([&]() {
|
||
auto state(_state.lock());
|
||
state->gcRunning = false;
|
||
state->lastGCCheck = std::chrono::steady_clock::now();
|
||
promise.set_value();
|
||
});
|
||
|
||
GCOptions options;
|
||
options.maxFreed = settings.maxFree - avail;
|
||
|
||
printInfo("running auto-GC to free %d bytes", options.maxFreed);
|
||
|
||
GCResults results;
|
||
|
||
collectGarbage(options, results);
|
||
|
||
_state.lock()->availAfterGC = getAvail();
|
||
|
||
} catch (...) {
|
||
// FIXME: we could propagate the exception to the
|
||
// future, but we don't really care.
|
||
ignoreException();
|
||
}
|
||
|
||
}).detach();
|
||
}
|
||
|
||
sync:
|
||
// Wait for the future outside of the state lock.
|
||
if (sync) future.get();
|
||
}
|
||
|
||
|
||
}
|