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LocalStore: Allow the physical and logical store directories to differ

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This is primarily to subsume the functionality of the
copy-from-other-stores substituter. For example, in the NixOS
installer, we can now do (assuming we're in the target chroot, and the
Nix store of the installation CD is bind-mounted on /tmp/nix):

  $ nix-build ... --option substituters 'local?state=/tmp/nix/var&real=/tmp/nix/store'

However, unlike copy-from-other-stores, this also allows write access
to such a store. One application might be fetching substitutes for
/nix/store in a situation where the user doesn't have sufficient
privileges to create /nix, e.g.:

  $ NIX_REMOTE="local?state=/home/alice/nix/var&real=/home/alice/nix/store" nix-build ...
This commit is contained in:
Eelco Dolstra 2016-06-02 15:08:18 +02:00
parent 064816ab98
commit 4494000e04
7 changed files with 68 additions and 158 deletions
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1
.gitignore vendored
View file

@ -44,7 +44,6 @@ Makefile.config
/scripts/nix-copy-closure /scripts/nix-copy-closure
/scripts/NixConfig.pm /scripts/NixConfig.pm
/scripts/NixManifest.pm /scripts/NixManifest.pm
/scripts/copy-from-other-stores.pl
/scripts/download-from-binary-cache.pl /scripts/download-from-binary-cache.pl
/scripts/find-runtime-roots.pl /scripts/find-runtime-roots.pl
/scripts/build-remote.pl /scripts/build-remote.pl

103
scripts/copy-from-other-stores.pl.in
View file

@ -1,103 +0,0 @@
#! @perl@ -w @perlFlags@
use utf8;
use strict;
use File::Basename;
use IO::Handle;
my $binDir = $ENV{"NIX_BIN_DIR"} || "@bindir@";
STDOUT->autoflush(1);
binmode STDERR, ":encoding(utf8)";
my @remoteStoresAll = split ':', ($ENV{"NIX_OTHER_STORES"} or "");
my @remoteStores;
foreach my $dir (@remoteStoresAll) {
push @remoteStores, glob($dir);
}
exit if scalar @remoteStores == 0;
print "\n";
$ENV{"NIX_REMOTE"} = "";
sub findStorePath {
my $storePath = shift;
foreach my $store (@remoteStores) {
my $sourcePath = "$store/store/" . basename $storePath;
next unless -e $sourcePath || -l $sourcePath;
$ENV{"NIX_DB_DIR"} = "$store/var/nix/db";
return ($store, $sourcePath) if
system("$binDir/nix-store --check-validity $storePath") == 0;
}
return undef;
}
if ($ARGV[0] eq "--query") {
while (<STDIN>) {
chomp;
my ($cmd, @args) = split " ", $_;
if ($cmd eq "have") {
foreach my $storePath (@args) {
print "$storePath\n" if defined findStorePath($storePath);
}
print "\n";
}
elsif ($cmd eq "info") {
foreach my $storePath (@args) {
my ($store, $sourcePath) = findStorePath($storePath);
next unless defined $store;
$ENV{"NIX_DB_DIR"} = "$store/var/nix/db";
my $deriver = `$binDir/nix-store --query --deriver $storePath`;
die "cannot query deriver of ‘$storePath’" if $? != 0;
chomp $deriver;
$deriver = "" if $deriver eq "unknown-deriver";
my @references = split "\n",
`$binDir/nix-store --query --references $storePath`;
die "cannot query references of ‘$storePath’" if $? != 0;
my $narSize = `$binDir/nix-store --query --size $storePath`;
die "cannot query size of ‘$storePath’" if $? != 0;
chomp $narSize;
print "$storePath\n";
print "$deriver\n";
print scalar @references, "\n";
print "$_\n" foreach @references;
print "0\n";
print "$narSize\n";
}
print "\n";
}
else { die "unknown command ‘$cmd’"; }
}
}
elsif ($ARGV[0] eq "--substitute") {
die unless scalar @ARGV == 3;
my $storePath = $ARGV[1];
my $destPath = $ARGV[2];
my ($store, $sourcePath) = findStorePath $storePath;
die unless $store;
print STDERR "\n*** Copying ‘$storePath’ from ‘$sourcePath’\n\n";
system("@coreutils@/cp", "-rpd", $sourcePath, $destPath) == 0
or die "cannot copy ‘$sourcePath’ to ‘$storePath’";
print "\n"; # no hash to verify
}
else { die; }

3
src/libstore/build.cc
View file

@ -1269,6 +1269,9 @@ void DerivationGoal::tryToBuild()
{ {
trace("trying to build"); trace("trying to build");
if (worker.store.storeDir != worker.store.realStoreDir)
throw Error("building with a diverted Nix store is not supported");
/* Check for the possibility that some other goal in this process /* Check for the possibility that some other goal in this process
has locked the output since we checked in haveDerivation(). has locked the output since we checked in haveDerivation().
(It can't happen between here and the lockPaths() call below (It can't happen between here and the lockPaths() call below

39
src/libstore/gc.cc
View file

@ -370,7 +370,6 @@ struct LocalStore::GCState
bool gcKeepDerivations; bool gcKeepDerivations;
unsigned long long bytesInvalidated; unsigned long long bytesInvalidated;
bool moveToTrash = true; bool moveToTrash = true;
Path trashDir;
bool shouldDelete; bool shouldDelete;
GCState(GCResults & results_) : results(results_), bytesInvalidated(0) { } GCState(GCResults & results_) : results(results_), bytesInvalidated(0) { }
}; };
@ -407,10 +406,12 @@ void LocalStore::deletePathRecursive(GCState & state, const Path & path)
invalidatePathChecked(path); invalidatePathChecked(path);
} }
Path realPath = realStoreDir + "/" + baseNameOf(path);
struct stat st; struct stat st;
if (lstat(path.c_str(), &st)) { if (lstat(realPath.c_str(), &st)) {
if (errno == ENOENT) return; if (errno == ENOENT) return;
throw SysError(format("getting status of %1%") % path); throw SysError(format("getting status of %1%") % realPath);
} }
printMsg(lvlInfo, format("deleting ‘%1%’") % path); printMsg(lvlInfo, format("deleting ‘%1%’") % path);
@ -427,20 +428,20 @@ void LocalStore::deletePathRecursive(GCState & state, const Path & path)
// if the path was not valid, need to determine the actual // if the path was not valid, need to determine the actual
// size. // size.
try { try {
if (chmod(path.c_str(), st.st_mode | S_IWUSR) == -1) if (chmod(realPath.c_str(), st.st_mode | S_IWUSR) == -1)
throw SysError(format("making ‘%1%’ writable") % path); throw SysError(format("making ‘%1%’ writable") % realPath);
Path tmp = state.trashDir + "/" + baseNameOf(path); Path tmp = trashDir + "/" + baseNameOf(path);
if (rename(path.c_str(), tmp.c_str())) if (rename(realPath.c_str(), tmp.c_str()))
throw SysError(format("unable to rename ‘%1%’ to ‘%2%’") % path % tmp); throw SysError(format("unable to rename ‘%1%’ to ‘%2%’") % realPath % tmp);
state.bytesInvalidated += size; state.bytesInvalidated += size;
} catch (SysError & e) { } catch (SysError & e) {
if (e.errNo == ENOSPC) { if (e.errNo == ENOSPC) {
printMsg(lvlInfo, format("note: can't create move ‘%1%’: %2%") % path % e.msg()); printMsg(lvlInfo, format("note: can't create move ‘%1%’: %2%") % realPath % e.msg());
deleteGarbage(state, path); deleteGarbage(state, realPath);
} }
} }
} else } else
deleteGarbage(state, path); deleteGarbage(state, realPath);
if (state.results.bytesFreed + state.bytesInvalidated > state.options.maxFreed) { if (state.results.bytesFreed + state.bytesInvalidated > state.options.maxFreed) {
printMsg(lvlInfo, format("deleted or invalidated more than %1% bytes; stopping") % state.options.maxFreed); printMsg(lvlInfo, format("deleted or invalidated more than %1% bytes; stopping") % state.options.maxFreed);
@ -508,7 +509,8 @@ void LocalStore::tryToDelete(GCState & state, const Path & path)
{ {
checkInterrupt(); checkInterrupt();
if (path == linksDir || path == state.trashDir) return; auto realPath = realStoreDir + "/" + baseNameOf(path);
if (realPath == linksDir || realPath == trashDir) return;
Activity act(*logger, lvlDebug, format("considering whether to delete ‘%1%’") % path); Activity act(*logger, lvlDebug, format("considering whether to delete ‘%1%’") % path);
@ -590,7 +592,6 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
{ {
GCState state(results); GCState state(results);
state.options = options; state.options = options;
state.trashDir = storeDir + "/trash";
state.gcKeepOutputs = settings.gcKeepOutputs; state.gcKeepOutputs = settings.gcKeepOutputs;
state.gcKeepDerivations = settings.gcKeepDerivations; state.gcKeepDerivations = settings.gcKeepDerivations;
@ -639,9 +640,9 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
that is not reachable from `roots' is garbage. */ that is not reachable from `roots' is garbage. */
if (state.shouldDelete) { if (state.shouldDelete) {
if (pathExists(state.trashDir)) deleteGarbage(state, state.trashDir); if (pathExists(trashDir)) deleteGarbage(state, trashDir);
try { try {
createDirs(state.trashDir); createDirs(trashDir);
} catch (SysError & e) { } catch (SysError & e) {
if (e.errNo == ENOSPC) { if (e.errNo == ENOSPC) {
printMsg(lvlInfo, format("note: can't create trash directory: %1%") % e.msg()); printMsg(lvlInfo, format("note: can't create trash directory: %1%") % e.msg());
@ -671,8 +672,8 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
try { try {
AutoCloseDir dir = opendir(storeDir.c_str()); AutoCloseDir dir = opendir(realStoreDir.c_str());
if (!dir) throw SysError(format("opening directory ‘%1%’") % storeDir); if (!dir) throw SysError(format("opening directory ‘%1%’") % realStoreDir);
/* Read the store and immediately delete all paths that /* Read the store and immediately delete all paths that
aren't valid. When using --max-freed etc., deleting aren't valid. When using --max-freed etc., deleting
@ -725,8 +726,8 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
fds.clear(); fds.clear();
/* Delete the trash directory. */ /* Delete the trash directory. */
printMsg(lvlInfo, format("deleting ‘%1%’") % state.trashDir); printMsg(lvlInfo, format("deleting ‘%1%’") % trashDir);
deleteGarbage(state, state.trashDir); deleteGarbage(state, trashDir);
/* Clean up the links directory. */ /* Clean up the links directory. */
if (options.action == GCOptions::gcDeleteDead || options.action == GCOptions::gcDeleteSpecific) { if (options.action == GCOptions::gcDeleteDead || options.action == GCOptions::gcDeleteSpecific) {

72
src/libstore/local-store.cc
View file

@ -38,10 +38,12 @@ namespace nix {
LocalStore::LocalStore(const Params & params) LocalStore::LocalStore(const Params & params)
: LocalFSStore(params) : LocalFSStore(params)
, realStoreDir(get(params, "real", storeDir))
, dbDir(get(params, "state", "") != "" ? get(params, "state", "") + "/db" : settings.nixDBPath) , dbDir(get(params, "state", "") != "" ? get(params, "state", "") + "/db" : settings.nixDBPath)
, linksDir(storeDir + "/.links") , linksDir(realStoreDir + "/.links")
, reservedPath(dbDir + "/reserved") , reservedPath(dbDir + "/reserved")
, schemaPath(dbDir + "/schema") , schemaPath(dbDir + "/schema")
, trashDir(realStoreDir + "/trash")
, requireSigs(settings.get("signed-binary-caches", std::string("")) != "") // FIXME: rename option , requireSigs(settings.get("signed-binary-caches", std::string("")) != "") // FIXME: rename option
, publicKeys(getDefaultPublicKeys()) , publicKeys(getDefaultPublicKeys())
{ {
@ -53,7 +55,7 @@ LocalStore::LocalStore(const Params & params)
} }
/* Create missing state directories if they don't already exist. */ /* Create missing state directories if they don't already exist. */
createDirs(storeDir); createDirs(realStoreDir);
makeStoreWritable(); makeStoreWritable();
createDirs(linksDir); createDirs(linksDir);
Path profilesDir = stateDir + "/profiles"; Path profilesDir = stateDir + "/profiles";
@ -83,21 +85,21 @@ LocalStore::LocalStore(const Params & params)
% settings.buildUsersGroup); % settings.buildUsersGroup);
else { else {
struct stat st; struct stat st;
if (stat(storeDir.c_str(), &st)) if (stat(realStoreDir.c_str(), &st))
throw SysError(format("getting attributes of path ‘%1%’") % storeDir); throw SysError(format("getting attributes of path ‘%1%’") % realStoreDir);
if (st.st_uid != 0 || st.st_gid != gr->gr_gid || (st.st_mode & ~S_IFMT) != perm) { if (st.st_uid != 0 || st.st_gid != gr->gr_gid || (st.st_mode & ~S_IFMT) != perm) {
if (chown(storeDir.c_str(), 0, gr->gr_gid) == -1) if (chown(realStoreDir.c_str(), 0, gr->gr_gid) == -1)
throw SysError(format("changing ownership of path ‘%1%’") % storeDir); throw SysError(format("changing ownership of path ‘%1%’") % realStoreDir);
if (chmod(storeDir.c_str(), perm) == -1) if (chmod(realStoreDir.c_str(), perm) == -1)
throw SysError(format("changing permissions on path ‘%1%’") % storeDir); throw SysError(format("changing permissions on path ‘%1%’") % realStoreDir);
} }
} }
} }
/* Ensure that the store and its parents are not symlinks. */ /* Ensure that the store and its parents are not symlinks. */
if (getEnv("NIX_IGNORE_SYMLINK_STORE") != "1") { if (getEnv("NIX_IGNORE_SYMLINK_STORE") != "1") {
Path path = storeDir; Path path = realStoreDir;
struct stat st; struct stat st;
while (path != "/") { while (path != "/") {
if (lstat(path.c_str(), &st)) if (lstat(path.c_str(), &st))
@ -343,15 +345,15 @@ void LocalStore::makeStoreWritable()
if (getuid() != 0) return; if (getuid() != 0) return;
/* Check if /nix/store is on a read-only mount. */ /* Check if /nix/store is on a read-only mount. */
struct statvfs stat; struct statvfs stat;
if (statvfs(storeDir.c_str(), &stat) != 0) if (statvfs(realStoreDir.c_str(), &stat) != 0)
throw SysError("getting info about the Nix store mount point"); throw SysError("getting info about the Nix store mount point");
if (stat.f_flag & ST_RDONLY) { if (stat.f_flag & ST_RDONLY) {
if (unshare(CLONE_NEWNS) == -1) if (unshare(CLONE_NEWNS) == -1)
throw SysError("setting up a private mount namespace"); throw SysError("setting up a private mount namespace");
if (mount(0, storeDir.c_str(), "none", MS_REMOUNT | MS_BIND, 0) == -1) if (mount(0, realStoreDir.c_str(), "none", MS_REMOUNT | MS_BIND, 0) == -1)
throw SysError(format("remounting %1% writable") % storeDir); throw SysError(format("remounting %1% writable") % realStoreDir);
} }
#endif #endif
} }
@ -917,23 +919,25 @@ void LocalStore::addToStore(const ValidPathInfo & info, const std::string & nar,
PathLocks outputLock; PathLocks outputLock;
Path realPath = realStoreDir + "/" + baseNameOf(info.path);
/* Lock the output path. But don't lock if we're being called /* Lock the output path. But don't lock if we're being called
from a build hook (whose parent process already acquired a from a build hook (whose parent process already acquired a
lock on this path). */ lock on this path). */
Strings locksHeld = tokenizeString<Strings>(getEnv("NIX_HELD_LOCKS")); Strings locksHeld = tokenizeString<Strings>(getEnv("NIX_HELD_LOCKS"));
if (find(locksHeld.begin(), locksHeld.end(), info.path) == locksHeld.end()) if (find(locksHeld.begin(), locksHeld.end(), info.path) == locksHeld.end())
outputLock.lockPaths({info.path}); outputLock.lockPaths({realPath});
if (repair || !isValidPath(info.path)) { if (repair || !isValidPath(info.path)) {
deletePath(info.path); deletePath(realPath);
StringSource source(nar); StringSource source(nar);
restorePath(info.path, source); restorePath(realPath, source);
canonicalisePathMetaData(info.path, -1); canonicalisePathMetaData(realPath, -1);
optimisePath(info.path); // FIXME: combine with hashPath() optimisePath(realPath); // FIXME: combine with hashPath()
registerValidPath(info); registerValidPath(info);
} }
@ -957,19 +961,21 @@ Path LocalStore::addToStoreFromDump(const string & dump, const string & name,
/* The first check above is an optimisation to prevent /* The first check above is an optimisation to prevent
unnecessary lock acquisition. */ unnecessary lock acquisition. */
PathLocks outputLock({dstPath}); Path realPath = realStoreDir + "/" + baseNameOf(dstPath);
PathLocks outputLock({realPath});
if (repair || !isValidPath(dstPath)) { if (repair || !isValidPath(dstPath)) {
deletePath(dstPath); deletePath(realPath);
if (recursive) { if (recursive) {
StringSource source(dump); StringSource source(dump);
restorePath(dstPath, source); restorePath(realPath, source);
} else } else
writeFile(dstPath, dump); writeFile(realPath, dump);
canonicalisePathMetaData(dstPath, -1); canonicalisePathMetaData(realPath, -1);
/* Register the SHA-256 hash of the NAR serialisation of /* Register the SHA-256 hash of the NAR serialisation of
the path in the database. We may just have computed it the path in the database. We may just have computed it
@ -980,9 +986,9 @@ Path LocalStore::addToStoreFromDump(const string & dump, const string & name,
hash.first = hashAlgo == htSHA256 ? h : hashString(htSHA256, dump); hash.first = hashAlgo == htSHA256 ? h : hashString(htSHA256, dump);
hash.second = dump.size(); hash.second = dump.size();
} else } else
hash = hashPath(htSHA256, dstPath); hash = hashPath(htSHA256, realPath);
optimisePath(dstPath); // FIXME: combine with hashPath() optimisePath(realPath); // FIXME: combine with hashPath()
ValidPathInfo info; ValidPathInfo info;
info.path = dstPath; info.path = dstPath;
@ -1026,21 +1032,23 @@ Path LocalStore::addTextToStore(const string & name, const string & s,
if (repair || !isValidPath(dstPath)) { if (repair || !isValidPath(dstPath)) {
PathLocks outputLock({dstPath}); Path realPath = realStoreDir + "/" + baseNameOf(dstPath);
PathLocks outputLock({realPath});
if (repair || !isValidPath(dstPath)) { if (repair || !isValidPath(dstPath)) {
deletePath(dstPath); deletePath(realPath);
writeFile(dstPath, s); writeFile(realPath, s);
canonicalisePathMetaData(dstPath, -1); canonicalisePathMetaData(realPath, -1);
StringSink sink; StringSink sink;
dumpString(s, sink); dumpString(s, sink);
auto hash = hashString(htSHA256, *sink.s); auto hash = hashString(htSHA256, *sink.s);
optimisePath(dstPath); optimisePath(realPath);
ValidPathInfo info; ValidPathInfo info;
info.path = dstPath; info.path = dstPath;
@ -1067,7 +1075,7 @@ Path LocalStore::createTempDirInStore()
/* There is a slight possibility that `tmpDir' gets deleted by /* There is a slight possibility that `tmpDir' gets deleted by
the GC between createTempDir() and addTempRoot(), so repeat the GC between createTempDir() and addTempRoot(), so repeat
until `tmpDir' exists. */ until `tmpDir' exists. */
tmpDir = createTempDir(storeDir); tmpDir = createTempDir(realStoreDir);
addTempRoot(tmpDir); addTempRoot(tmpDir);
} while (!pathExists(tmpDir)); } while (!pathExists(tmpDir));
return tmpDir; return tmpDir;
@ -1107,7 +1115,7 @@ bool LocalStore::verifyStore(bool checkContents, bool repair)
AutoCloseFD fdGCLock = openGCLock(ltWrite); AutoCloseFD fdGCLock = openGCLock(ltWrite);
PathSet store; PathSet store;
for (auto & i : readDirectory(storeDir)) store.insert(i.name); for (auto & i : readDirectory(realStoreDir)) store.insert(i.name);
/* Check whether all valid paths actually exist. */ /* Check whether all valid paths actually exist. */
printMsg(lvlInfo, "checking path existence..."); printMsg(lvlInfo, "checking path existence...");
@ -1271,7 +1279,7 @@ void LocalStore::upgradeStore7()
{ {
if (getuid() != 0) return; if (getuid() != 0) return;
printMsg(lvlError, "removing immutable bits from the Nix store (this may take a while)..."); printMsg(lvlError, "removing immutable bits from the Nix store (this may take a while)...");
makeMutable(storeDir); makeMutable(realStoreDir);
} }
#else #else

2
src/libstore/local-store.hh
View file

@ -73,10 +73,12 @@ private:
Sync<State, std::recursive_mutex> _state; Sync<State, std::recursive_mutex> _state;
const Path realStoreDir;
const Path dbDir; const Path dbDir;
const Path linksDir; const Path linksDir;
const Path reservedPath; const Path reservedPath;
const Path schemaPath; const Path schemaPath;
const Path trashDir;
bool requireSigs; bool requireSigs;

6
src/libstore/optimise-store.cc
View file

@ -176,7 +176,7 @@ void LocalStore::optimisePath_(OptimiseStats & stats, const Path & path, InodeHa
/* Make the containing directory writable, but only if it's not /* Make the containing directory writable, but only if it's not
the store itself (we don't want or need to mess with its the store itself (we don't want or need to mess with its
permissions). */ permissions). */
bool mustToggle = !isStorePath(path); bool mustToggle = dirOf(path) != realStoreDir;
if (mustToggle) makeWritable(dirOf(path)); if (mustToggle) makeWritable(dirOf(path));
/* When we're done, make the directory read-only again and reset /* When we're done, make the directory read-only again and reset
@ -184,7 +184,7 @@ void LocalStore::optimisePath_(OptimiseStats & stats, const Path & path, InodeHa
MakeReadOnly makeReadOnly(mustToggle ? dirOf(path) : ""); MakeReadOnly makeReadOnly(mustToggle ? dirOf(path) : "");
Path tempLink = (format("%1%/.tmp-link-%2%-%3%") Path tempLink = (format("%1%/.tmp-link-%2%-%3%")
% storeDir % getpid() % rand()).str(); % realStoreDir % getpid() % rand()).str();
if (link(linkPath.c_str(), tempLink.c_str()) == -1) { if (link(linkPath.c_str(), tempLink.c_str()) == -1) {
if (errno == EMLINK) { if (errno == EMLINK) {
@ -229,7 +229,7 @@ void LocalStore::optimiseStore(OptimiseStats & stats)
addTempRoot(i); addTempRoot(i);
if (!isValidPath(i)) continue; /* path was GC'ed, probably */ if (!isValidPath(i)) continue; /* path was GC'ed, probably */
Activity act(*logger, lvlChatty, format("hashing files in ‘%1%’") % i); Activity act(*logger, lvlChatty, format("hashing files in ‘%1%’") % i);
optimisePath_(stats, i, inodeHash); optimisePath_(stats, realStoreDir + "/" + baseNameOf(i), inodeHash);
} }
} }