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packed_ref_store: handle a packed-refs file that is a symlink

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One of the tricks that `contrib/workdir/git-new-workdir` plays is to
making `packed-refs` in the new workdir a symlink to the `packed-refs`
file in the original repository. Before
42dfa7ecef ("commit_packed_refs(): use a staging file separate from
the lockfile", 2017-06-23), a lockfile was used as the staging file,
and because the `LOCK_NO_DEREF` was not used, the pointed-to file was
locked and modified.

But after that commit, the staging file was created using a tempfile,
with the end result that rewriting the `packed-refs` file in the
workdir overwrote the symlink rather than the original `packed-refs`
file.

Change `commit_packed_refs()` to use `get_locked_file_path()` to find
the path of the file that it should overwrite. Since that path was
properly resolved when the lockfile was created, this restores the
pre-42dfa7ecef behavior.

Also add a test case to document this use case and prevent a
regression like this from recurring.

Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
Michael Haggerty 2017-07-26 16:39:42 -07:00 committed by Junio C Hamano
parent 9308b7f3ca
commit 198b808e20
2 changed files with 33 additions and 6 deletions
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24
refs/packed-backend.c
View file

@ -610,19 +610,27 @@ int commit_packed_refs(struct ref_store *ref_store, struct strbuf *err)
struct packed_ref_cache *packed_ref_cache =
get_packed_ref_cache(refs);
int ok;
int ret = -1;
struct strbuf sb = STRBUF_INIT;
FILE *out;
struct ref_iterator *iter;
char *packed_refs_path;
if (!is_lock_file_locked(&refs->lock))
die("BUG: commit_packed_refs() called when unlocked");
strbuf_addf(&sb, "%s.new", refs->path);
/*
* If packed-refs is a symlink, we want to overwrite the
* symlinked-to file, not the symlink itself. Also, put the
* staging file next to it:
*/
packed_refs_path = get_locked_file_path(&refs->lock);
strbuf_addf(&sb, "%s.new", packed_refs_path);
if (create_tempfile(&refs->tempfile, sb.buf) < 0) {
strbuf_addf(err, "unable to create file %s: %s",
sb.buf, strerror(errno));
strbuf_release(&sb);
return -1;
goto out;
}
strbuf_release(&sb);
@ -660,17 +668,21 @@ int commit_packed_refs(struct ref_store *ref_store, struct strbuf *err)
goto error;
}
if (rename_tempfile(&refs->tempfile, refs->path)) {
if (rename_tempfile(&refs->tempfile, packed_refs_path)) {
strbuf_addf(err, "error replacing %s: %s",
refs->path, strerror(errno));
return -1;
goto out;
}
return 0;
ret = 0;
goto out;
error:
delete_tempfile(&refs->tempfile);
return -1;
out:
free(packed_refs_path);
return ret;
}
/*

15
t/t3210-pack-refs.sh
View file

@ -238,4 +238,19 @@ test_expect_success 'retry acquiring packed-refs.lock' '
git -c core.packedrefstimeout=3000 pack-refs --all --prune
'
test_expect_success SYMLINKS 'pack symlinked packed-refs' '
# First make sure that symlinking works when reading:
git update-ref refs/heads/loosy refs/heads/master &&
git for-each-ref >all-refs-before &&
mv .git/packed-refs .git/my-deviant-packed-refs &&
ln -s my-deviant-packed-refs .git/packed-refs &&
git for-each-ref >all-refs-linked &&
test_cmp all-refs-before all-refs-linked &&
git pack-refs --all --prune &&
git for-each-ref >all-refs-packed &&
test_cmp all-refs-before all-refs-packed &&
test -h .git/packed-refs &&
test "$(readlink .git/packed-refs)" = "my-deviant-packed-refs"
'
test_done