Commit 40ffa07f4ff3616acb814ff3ef93df7206f5b5c5
2015-12-31T14:51:42
sortedcache: check file size after opening the file Checking the size before we open the file descriptor can lead to the file being replaced from under us when renames aren't quite atomic, so we can end up reading too little of the file, leading to us thinking the file is corrupted.
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diff --git a/src/sortedcache.c b/src/sortedcache.c
index 5c2a167..ed4199b 100644
--- a/src/sortedcache.c
+++ b/src/sortedcache.c
@@ -200,6 +200,7 @@ void git_sortedcache_runlock(git_sortedcache *sc)
int git_sortedcache_lockandload(git_sortedcache *sc, git_buf *buf)
{
int error, fd;
+ struct stat st;
if ((error = git_sortedcache_wlock(sc)) < 0)
return error;
@@ -207,19 +208,26 @@ int git_sortedcache_lockandload(git_sortedcache *sc, git_buf *buf)
if ((error = git_futils_filestamp_check(&sc->stamp, sc->path)) <= 0)
goto unlock;
- if (!git__is_sizet(sc->stamp.size)) {
- giterr_set(GITERR_INVALID, "Unable to load file larger than size_t");
+ if ((fd = git_futils_open_ro(sc->path)) < 0) {
+ error = fd;
+ goto unlock;
+ }
+
+ if (p_fstat(fd, &st) < 0) {
+ giterr_set(GITERR_OS, "failed to stat file");
error = -1;
goto unlock;
}
- if ((fd = git_futils_open_ro(sc->path)) < 0) {
- error = fd;
+ if (!git__is_sizet(st.st_size)) {
+ giterr_set(GITERR_INVALID, "Unable to load file larger than size_t");
+ error = -1;
+ (void)p_close(fd);
goto unlock;
}
if (buf)
- error = git_futils_readbuffer_fd(buf, fd, (size_t)sc->stamp.size);
+ error = git_futils_readbuffer_fd(buf, fd, (size_t)st.st_size);
(void)p_close(fd);