[PATCH 2/2] pack-refs: add fully-peeled trait
- From
Jeff King <peff@peff.net>
- Date
- Mar 16, 2013, 09:01 UTC
- Message-ID
- <20130316090116.GB26855@sigill.intra.peff.net>
- In-Reply-To
- <20130316090018.GA26708@sigill.intra.peff.net>
Older versions of pack-refs did not write peel lines for refs outside of refs/tags. This meant that on reading the pack-refs file, we might set the REF_KNOWS_PEELED flag for such a ref, even though we do not know anything about its peeled value.
The previous commit updated the writer to always peel, no matter what the ref is. That means that packed-refs files written by newer versions of git are fine to be read by both old and new versions of git. However, we still have the problem of reading packed-refs files written by older versions of git, or by other implementations which have not yet learned the same trick.
The simplest fix would be to always unset the REF_KNOWS_PEELED flag for refs outside of refs/tags that do not have a peel line (if it has a peel line, we know it is valid, but we cannot assume a missing peel line means anything). But that loses an important optimization, as upload-pack should not need to load the object pointed to by refs/heads/foo to determine that it is not a tag.
Instead, we add a "fully-peeled" trait to the packed-refs file. If it is set, we know that we can trust a missing peel line to mean that a ref cannot be peeled. Otherwise, we fall back to assuming nothing.
Signed-off-by: Jeff King <peff@peff.net> --- pack-refs.c | 2 +- refs.c | 16 +++++++++++++++- t/t3211-peel-ref.sh | 22 ++++++++++++++++++++++ 3 files changed, 38 insertions(+), 2 deletions(-)
diff --git a/pack-refs.c b/pack-refs.c index 10832d7..87ca04d 100644 --- a/pack-refs.c +++ b/pack-refs.c @@ -128,7 +128,7 @@ int pack_refs(unsigned int flags) die_errno("unable to create ref-pack file structure"); /* perhaps other traits later as well */ - fprintf(cbdata.refs_file, "# pack-refs with: peeled \n"); + fprintf(cbdata.refs_file, "# pack-refs with: peeled fully-peeled \n"); for_each_ref(handle_one_ref, &cbdata); if (ferror(cbdata.refs_file)) diff --git a/refs.c b/refs.c index 175b9fc..6a38c41 100644 --- a/refs.c +++ b/refs.c @@ -808,6 +808,7 @@ static void read_packed_refs(FILE *f, struct ref_dir *dir) struct ref_entry *last = NULL; char refline[PATH_MAX]; int flag = REF_ISPACKED; + int fully_peeled = 0; while (fgets(refline, sizeof(refline), f)) { unsigned char sha1[20]; @@ -818,13 +819,26 @@ static void read_packed_refs(FILE *f, struct ref_dir *dir) const char *traits = refline + sizeof(header) - 1; if (strstr(traits, " peeled ")) flag |= REF_KNOWS_PEELED; + if (strstr(traits, " fully-peeled ")) + fully_peeled = 1; /* perhaps other traits later as well */ continue; } refname = parse_ref_line(refline, sha1); if (refname) { - last = create_ref_entry(refname, sha1, flag, 1); + /* + * Older git did not write peel lines for anything + * outside of refs/tags/; if the fully-peeled trait + * is not set, we are dealing with such an older + * git and cannot assume an omitted peel value + * means the ref is not a tag object. + */ + int this_flag = flag; + if (!fully_peeled && prefixcmp(refname, "refs/tags/")) + this_flag &= ~REF_KNOWS_PEELED; + + last = create_ref_entry(refname, sha1, this_flag, 1); add_ref(dir, last); continue; } diff --git a/t/t3211-peel-ref.sh b/t/t3211-peel-ref.sh index dd5b48b..a8eb1aa 100755 --- a/t/t3211-peel-ref.sh +++ b/t/t3211-peel-ref.sh @@ -39,4 +39,26 @@ test_expect_success 'refs are peeled outside of refs/tags (packed)' ' test_cmp expect actual ' +test_expect_success 'create old-style pack-refs without fully-peeled' ' + # Git no longer writes without fully-peeled, so we just write our own + # from scratch; we could also munge the existing file to remove the + # fully-peeled bits, but that seems even more prone to failure, + # especially if the format ever changes again. At least this way we + # know we are emulating exactly what an older git would have written. + { + echo "# pack-refs with: peeled " && + print_ref "refs/heads/master" && + print_ref "refs/outside/foo" && + print_ref "refs/tags/base" && + print_ref "refs/tags/foo" && + echo "^$(git rev-parse "refs/tags/foo^{}")" + } >tmp && + mv tmp .git/packed-refs +' + +test_expect_success 'refs are peeled outside of refs/tags (old packed)' ' + git show-ref -d >actual && + test_cmp expect actual +' + test_done
-- 1.8.2.rc2.7.gef06216