[PATCH] fetch-pack: always allow fetching of literal SHA1s

[Jonathan Tan]

fetch-pack, when fetching a literal SHA-1 from a server that is not
configured with uploadpack.allowtipsha1inwant (or similar), always
returns an error message of the form "Server does not allow request for
unadvertised object %s". However, it is sometimes the case that such
object is advertised.

Teach fetch-pack to also check the SHA-1s of the refs in the received
ref advertisement if a literal SHA-1 was given by the user.

Signed-off-by: Jonathan Tan <jonathanta...@google.com>
---
 fetch-pack.c          | 30 ++++++++++++++++--------------
 t/t5500-fetch-pack.sh |  6 ++++++
 2 files changed, 22 insertions(+), 14 deletions(-)

diff --git a/fetch-pack.c b/fetch-pack.c
index afb8b0502..180405dff 100644
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -592,6 +592,14 @@ static void mark_recent_complete_commits(struct 
fetch_pack_args *args,
        }
 }
 
+static int is_literal_sha1(const struct ref *ref)
+{
+       struct object_id oid;
+       return !get_oid_hex(ref->name, &oid) &&
+              !ref->name[40] &&
+              !oidcmp(&oid, &ref->old_oid);
+}
+
 static void filter_refs(struct fetch_pack_args *args,
                        struct ref **refs,
                        struct ref **sought, int nr_sought)
@@ -601,7 +609,6 @@ static void filter_refs(struct fetch_pack_args *args,
        struct ref *ref, *next;
        int i;
 
-       i = 0;
        for (ref = *refs; ref; ref = next) {
                int keep = 0;
                next = ref->next;
@@ -610,15 +617,14 @@ static void filter_refs(struct fetch_pack_args *args,
                    check_refname_format(ref->name, 0))
                        ; /* trash */
                else {
-                       while (i < nr_sought) {
-                               int cmp = strcmp(ref->name, sought[i]->name);
-                               if (cmp < 0)
-                                       break; /* definitely do not have it */
-                               else if (cmp == 0) {
-                                       keep = 1; /* definitely have it */
-                                       sought[i]->match_status = REF_MATCHED;
+                       for (i = 0; i < nr_sought; i++) {
+                               struct ref *s = sought[i];
+                               if (!strcmp(ref->name, s->name) ||
+                                   (is_literal_sha1(s) &&
+                                    !oidcmp(&ref->old_oid, &s->old_oid))) {
+                                       keep = 1;
+                                       s->match_status = REF_MATCHED;
                                }
-                               i++;
                        }
                }
 
@@ -637,14 +643,10 @@ static void filter_refs(struct fetch_pack_args *args,
 
        /* Append unmatched requests to the list */
        for (i = 0; i < nr_sought; i++) {
-               unsigned char sha1[20];
-
                ref = sought[i];
                if (ref->match_status != REF_NOT_MATCHED)
                        continue;
-               if (get_sha1_hex(ref->name, sha1) ||
-                   ref->name[40] != '\0' ||
-                   hashcmp(sha1, ref->old_oid.hash))
+               if (!is_literal_sha1(ref))
                        continue;
 
                if ((allow_unadvertised_object_request &
diff --git a/t/t5500-fetch-pack.sh b/t/t5500-fetch-pack.sh
index b5865b385..d87983bc2 100755
--- a/t/t5500-fetch-pack.sh
+++ b/t/t5500-fetch-pack.sh
@@ -547,6 +547,12 @@ test_expect_success 'fetch-pack can fetch a raw sha1' '
        git fetch-pack hidden $(git -C hidden rev-parse refs/hidden/one)
 '
 
+test_expect_success 'fetch-pack can fetch a raw sha1 that is advertised as a 
ref' '
+       git init server &&
+       test_commit -C server 4 &&
+       git fetch-pack server $(git -C server rev-parse refs/heads/master)
+'
+
 check_prot_path () {
        cat >expected <<-EOF &&
        Diag: url=$1
-- 
2.13.0.rc2.291.g57267f2277-goog