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* In addPermRoot, check that the root that we just registered can be

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found by the garbage collector.  This addresses NIX-71 and is a
  particular concern in multi-user stores.
This commit is contained in:
Eelco Dolstra 2006-12-05 00:34:42 +00:00
parent 74033a844f
commit d27a73b1a9
2 changed files with 42 additions and 18 deletions
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2
src/libmain/shared.cc
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@ -47,7 +47,7 @@ void printGCWarning()
{ {
static bool haveWarned = false; static bool haveWarned = false;
warnOnce(haveWarned, warnOnce(haveWarned,
"warning: you did not specify `--add-root'; " "you did not specify `--add-root'; "
"the result might be removed by the garbage collector"); "the result might be removed by the garbage collector");
} }

58
src/libstore/gc.cc
View file

@ -91,6 +91,9 @@ void LocalStore::addIndirectRoot(const Path & path)
} }
static void findRoots(PathSet & roots, bool ignoreUnreadable);
Path addPermRoot(const Path & _storePath, const Path & _gcRoot, Path addPermRoot(const Path & _storePath, const Path & _gcRoot,
bool indirect, bool allowOutsideRootsDir) bool indirect, bool allowOutsideRootsDir)
{ {
@ -115,6 +118,18 @@ Path addPermRoot(const Path & _storePath, const Path & _gcRoot,
} }
createSymlink(gcRoot, storePath, false); createSymlink(gcRoot, storePath, false);
/* Check that the root can be found by the garbage collector. */
PathSet roots;
findRoots(roots, true);
if (roots.find(storePath) == roots.end()) {
static bool haveWarned = false;
warnOnce(haveWarned,
format(
"the path `%1%' is not reachable from the roots directory of the garbage collector; "
"therefore, `%2%' might be removed by the garbage collector")
% gcRoot % storePath);
}
} }
/* Grab the global GC root, causing us to block while a GC is in /* Grab the global GC root, causing us to block while a GC is in
@ -292,7 +307,7 @@ static void readTempRoots(PathSet & tempRoots, FDs & fds)
static void findRoots(const Path & path, bool recurseSymlinks, static void findRoots(const Path & path, bool recurseSymlinks,
PathSet & roots) bool ignoreUnreadable, PathSet & roots)
{ {
struct stat st; struct stat st;
if (lstat(path.c_str(), &st) == -1) if (lstat(path.c_str(), &st) == -1)
@ -303,39 +318,50 @@ static void findRoots(const Path & path, bool recurseSymlinks,
if (S_ISDIR(st.st_mode)) { if (S_ISDIR(st.st_mode)) {
Strings names = readDirectory(path); Strings names = readDirectory(path);
for (Strings::iterator i = names.begin(); i != names.end(); ++i) for (Strings::iterator i = names.begin(); i != names.end(); ++i)
findRoots(path + "/" + *i, recurseSymlinks, roots); findRoots(path + "/" + *i, recurseSymlinks, ignoreUnreadable, roots);
} }
else if (S_ISLNK(st.st_mode)) { else if (S_ISLNK(st.st_mode)) {
string target = readLink(path); Path target = absPath(readLink(path), dirOf(path));
Path target2 = absPath(target, dirOf(path));
if (isInStore(target2)) { if (isInStore(target)) {
debug(format("found root `%1%' in `%2%'") debug(format("found root `%1%' in `%2%'")
% target2 % path); % target % path);
Path target3 = toStorePath(target2); Path storePath = toStorePath(target);
if (store->isValidPath(target3)) if (store->isValidPath(storePath))
roots.insert(target3); roots.insert(storePath);
else else
printMsg(lvlInfo, format("skipping invalid root from `%1%' to `%2%'") printMsg(lvlInfo, format("skipping invalid root from `%1%' to `%2%'")
% path % target3); % path % storePath);
} }
else if (recurseSymlinks) { else if (recurseSymlinks) {
if (pathExists(target2)) struct stat st2;
findRoots(target2, false, roots); if (lstat(target.c_str(), &st2) == 0)
else { findRoots(target, false, ignoreUnreadable, roots);
printMsg(lvlInfo, format("removing stale link from `%1%' to `%2%'") % path % target2); else if (ignoreUnreadable && errno == EACCES)
/* ignore */ ;
else if (errno == ENOENT || errno == ENOTDIR) {
printMsg(lvlInfo, format("removing stale link from `%1%' to `%2%'") % path % target);
/* Note that we only delete when recursing, i.e., when /* Note that we only delete when recursing, i.e., when
we are still in the `gcroots' tree. We never we are still in the `gcroots' tree. We never
delete stuff outside that tree. */ delete stuff outside that tree. */
unlink(path.c_str()); unlink(path.c_str());
} }
else
throw SysError(format("statting `%1%'") % target);
} }
} }
} }
static void findRoots(PathSet & roots, bool ignoreUnreadable)
{
Path rootsDir = canonPath((format("%1%/%2%") % nixStateDir % gcRootsDir).str());
findRoots(rootsDir, true, ignoreUnreadable, roots);
}
static void addAdditionalRoots(PathSet & roots) static void addAdditionalRoots(PathSet & roots)
{ {
Path rootFinder = getEnv("NIX_ROOT_FINDER", Path rootFinder = getEnv("NIX_ROOT_FINDER",
@ -410,10 +436,8 @@ void collectGarbage(GCAction action, const PathSet & pathsToDelete,
/* Find the roots. Since we've grabbed the GC lock, the set of /* Find the roots. Since we've grabbed the GC lock, the set of
permanent roots cannot increase now. */ permanent roots cannot increase now. */
Path rootsDir = canonPath((format("%1%/%2%") % nixStateDir % gcRootsDir).str());
PathSet roots; PathSet roots;
if (!ignoreLiveness) findRoots(roots, false);
findRoots(rootsDir, true, roots);
/* Add additional roots returned by the program specified by the /* Add additional roots returned by the program specified by the
NIX_ROOT_FINDER environment variable. This is typically used NIX_ROOT_FINDER environment variable. This is typically used