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authorMichael Haggerty <mhagger@alum.mit.edu>2013-03-18 07:37:32 -0400
committerJunio C Hamano <gitster@pobox.com>2013-03-18 08:06:28 -0700
commitc29c46fa2e21e608ce2e603649af5bf38e7969c2 (patch)
tree80f08454a52aac4afe31b7bf0c7cb9c82bce417a /refs.c
parent03a8eddfd1bd7cdce0b2361753691f53c00e5ba6 (diff)
downloadgit-c29c46fa2e21e608ce2e603649af5bf38e7969c2.tar.gz
pack-refs: add fully-peeled trait
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. [commit message and tests by Jeff King <peff@peff.net>] Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu> Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'refs.c')
-rw-r--r--refs.c49
1 files changed, 44 insertions, 5 deletions
diff --git a/refs.c b/refs.c
index da74a2b29a..f5d954c27e 100644
--- a/refs.c
+++ b/refs.c
@@ -804,11 +804,38 @@ static const char *parse_ref_line(char *line, unsigned char *sha1)
return line;
}
+/*
+ * Read f, which is a packed-refs file, into dir.
+ *
+ * A comment line of the form "# pack-refs with: " may contain zero or
+ * more traits. We interpret the traits as follows:
+ *
+ * No traits:
+ *
+ * Probably no references are peeled. But if the file contains a
+ * peeled value for a reference, we will use it.
+ *
+ * peeled:
+ *
+ * References under "refs/tags/", if they *can* be peeled, *are*
+ * peeled in this file. References outside of "refs/tags/" are
+ * probably not peeled even if they could have been, but if we find
+ * a peeled value for such a reference we will use it.
+ *
+ * fully-peeled:
+ *
+ * All references in the file that can be peeled are peeled.
+ * Inversely (and this is more important), any references in the
+ * file for which no peeled value is recorded is not peelable. This
+ * trait should typically be written alongside "peeled" for
+ * compatibility with older clients, but we do not require it
+ * (i.e., "peeled" is a no-op if "fully-peeled" is set).
+ */
static void read_packed_refs(FILE *f, struct ref_dir *dir)
{
struct ref_entry *last = NULL;
char refline[PATH_MAX];
- int flag = REF_ISPACKED;
+ enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
while (fgets(refline, sizeof(refline), f)) {
unsigned char sha1[20];
@@ -817,15 +844,20 @@ static void read_packed_refs(FILE *f, struct ref_dir *dir)
if (!strncmp(refline, header, sizeof(header)-1)) {
const char *traits = refline + sizeof(header) - 1;
- if (strstr(traits, " peeled "))
- flag |= REF_KNOWS_PEELED;
+ if (strstr(traits, " fully-peeled "))
+ peeled = PEELED_FULLY;
+ else if (strstr(traits, " peeled "))
+ peeled = PEELED_TAGS;
/* perhaps other traits later as well */
continue;
}
refname = parse_ref_line(refline, sha1);
if (refname) {
- last = create_ref_entry(refname, sha1, flag, 1);
+ last = create_ref_entry(refname, sha1, REF_ISPACKED, 1);
+ if (peeled == PEELED_FULLY ||
+ (peeled == PEELED_TAGS && !prefixcmp(refname, "refs/tags/")))
+ last->flag |= REF_KNOWS_PEELED;
add_ref(dir, last);
continue;
}
@@ -833,8 +865,15 @@ static void read_packed_refs(FILE *f, struct ref_dir *dir)
refline[0] == '^' &&
strlen(refline) == 42 &&
refline[41] == '\n' &&
- !get_sha1_hex(refline + 1, sha1))
+ !get_sha1_hex(refline + 1, sha1)) {
hashcpy(last->u.value.peeled, sha1);
+ /*
+ * Regardless of what the file header said,
+ * we definitely know the value of *this*
+ * reference:
+ */
+ last->flag |= REF_KNOWS_PEELED;
+ }
}
}