Do not feed rev-list an invalid SHA1 expression.

The previous round to optimize fetch-pack has a small bug that
feeds SHA1^ ("parent commit") before making sure SHA1 is
actually a commit (or a tag that eventually dereferences to a
commit).  Also it did not help culling the known-to-be-common
parents if the common one was a merge.

Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/fetch-pack.c b/fetch-pack.c
index 9dfd072..4ee91f2 100644 (file)
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -28,22 +28,36 @@ static int find_common(int fd[2], unsigned char *result_sha1,
        fetching = 0;
        for ( ; refs ; refs = refs->next) {
                unsigned char *remote = refs->old_sha1;
+               struct object *o;
 
                /*
-                  If that object is complete (i.e. it is a descendant of a
-                  local ref), we don't want it, nor its descendants.
-               */
-               if (has_sha1_file(remote)
-                               && parse_object(remote)->flags & COMPLETE) {
-                       if (rev_command_len + 44 < sizeof(rev_command)) {
+                * If that object is complete (i.e. it is an ancestor of a
+                * local ref), we tell them we have it but do not have to
+                * tell them about its ancestors, which they already know
+                * about.
+                */
+               if (has_sha1_file(remote) &&
+                   ((o = parse_object(remote)) != NULL) &&
+                   (o->flags & COMPLETE)) {
+                       struct commit_list *p;
+                       struct commit *commit =
+                               (struct commit *) (o = deref_tag(o));
+                       if (!o)
+                               goto repair;
+                       if (o->type != commit_type)
+                               continue;
+                       p = commit->parents;
+                       while (p &&
+                              rev_command_len + 44 < sizeof(rev_command)) {
                                snprintf(rev_command + rev_command_len, 44,
-                                       " ^%s^", sha1_to_hex(remote));
+                                        " ^%s",
+                                        sha1_to_hex(p->item->object.sha1));
                                rev_command_len += 43;
+                               p = p->next;
                        }
-
                        continue;
                }
-
+       repair:
                packet_write(fd[1], "want %s\n", sha1_to_hex(remote));
                fetching++;
        }