Be careful when dereferencing tags.

One caller of deref_tag() was not careful enough to make sure
what deref_tag() returned was not NULL (i.e. we found a tag
object that points at an object we do not have).  Fix it, and
warn about refs that point at such an incomplete tag where
needed.

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

diff --git a/commit.c b/commit.c
index 8f40318..a8c9bfc 100644 (file)
--- a/commit.c
+++ b/commit.c
@@ -55,7 +55,7 @@ static struct commit *check_commit(struct object *obj,
 struct commit *lookup_commit_reference_gently(const unsigned char *sha1,
                                              int quiet)
 {
-       struct object *obj = deref_tag(parse_object(sha1));
+       struct object *obj = deref_tag(parse_object(sha1), NULL, 0);
 
        if (!obj)
                return NULL;

diff --git a/fetch-pack.c b/fetch-pack.c
index 3df9911..cb21715 100644 (file)
--- a/fetch-pack.c
+++ b/fetch-pack.c
@@ -38,9 +38,9 @@ static void rev_list_push(struct commit *commit, int mark)
 
 static int rev_list_insert_ref(const char *path, const unsigned char *sha1)
 {
-       struct object *o = deref_tag(parse_object(sha1));
+       struct object *o = deref_tag(parse_object(sha1), path, 0);
 
-       if (o->type == commit_type)
+       if (o && o->type == commit_type)
                rev_list_push((struct commit *)o, SEEN);
 
        return 0;
@@ -317,7 +317,8 @@ static int everything_local(struct ref **refs, int nr_match, char **match)
         * Don't mark them common yet; the server has to be told so first.
         */
        for (ref = *refs; ref; ref = ref->next) {
-               struct object *o = deref_tag(lookup_object(ref->old_sha1));
+               struct object *o = deref_tag(lookup_object(ref->old_sha1),
+                                            NULL, 0);
 
                if (!o || o->type != commit_type || !(o->flags & COMPLETE))
                        continue;

diff --git a/name-rev.c b/name-rev.c
index 21fecdf..59194f1 100644 (file)
--- a/name-rev.c
+++ b/name-rev.c
@@ -164,7 +164,7 @@ int main(int argc, char **argv)
                        continue;
                }
 
-               o = deref_tag(parse_object(sha1));
+               o = deref_tag(parse_object(sha1), *argv, 0);
                if (!o || o->type != commit_type) {
                        fprintf(stderr, "Could not get commit for %s. Skipping.\n",
                                        *argv);

diff --git a/send-pack.c b/send-pack.c
index 9f9a6e7..3eeb18f 100644 (file)
--- a/send-pack.c
+++ b/send-pack.c
@@ -126,12 +126,12 @@ static int ref_newer(const unsigned char *new_sha1,
        /* Both new and old must be commit-ish and new is descendant of
         * old.  Otherwise we require --force.
         */
-       o = deref_tag(parse_object(old_sha1));
+       o = deref_tag(parse_object(old_sha1), NULL, 0);
        if (!o || o->type != commit_type)
                return 0;
        old = (struct commit *) o;
 
-       o = deref_tag(parse_object(new_sha1));
+       o = deref_tag(parse_object(new_sha1), NULL, 0);
        if (!o || o->type != commit_type)
                return 0;
        new = (struct commit *) o;

diff --git a/server-info.c b/server-info.c
index ba53591..0cba8e1 100644 (file)
--- a/server-info.c
+++ b/server-info.c
@@ -13,9 +13,10 @@ static int add_info_ref(const char *path, const unsigned char *sha1)
 
        fprintf(info_ref_fp, "%s        %s\n", sha1_to_hex(sha1), path);
        if (o->type == tag_type) {
-               o = deref_tag(o);
-               fprintf(info_ref_fp, "%s        %s^{}\n",
-                       sha1_to_hex(o->sha1), path);
+               o = deref_tag(o, path, 0);
+               if (o)
+                       fprintf(info_ref_fp, "%s        %s^{}\n",
+                               sha1_to_hex(o->sha1), path);
        }
        return 0;
 }

diff --git a/sha1_name.c b/sha1_name.c
index fe409fb..be1755a 100644 (file)
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -349,7 +349,7 @@ static int peel_onion(const char *name, int len, unsigned char *sha1)
        if (!o)
                return -1;
        if (!type_string) {
-               o = deref_tag(o);
+               o = deref_tag(o, name, sp - name - 2);
                if (!o || (!o->parsed && !parse_object(o->sha1)))
                        return -1;
                memcpy(sha1, o->sha1, 20);

diff --git a/tag.c b/tag.c
index b1ab75f..e574c4b 100644 (file)
--- a/tag.c
+++ b/tag.c
@@ -3,10 +3,15 @@
 
 const char *tag_type = "tag";
 
-struct object *deref_tag(struct object *o)
+struct object *deref_tag(struct object *o, const char *warn, int warnlen)
 {
        while (o && o->type == tag_type)
                o = parse_object(((struct tag *)o)->tagged->sha1);
+       if (!o && warn) {
+               if (!warnlen)
+                       warnlen = strlen(warn);
+               error("missing object referenced by '%.*s'", warnlen, warn);
+       }
        return o;
 }
 

diff --git a/tag.h b/tag.h
index 36e5324..7a0cb00 100644 (file)
--- a/tag.h
+++ b/tag.h
@@ -15,6 +15,6 @@ struct tag {
 extern struct tag *lookup_tag(const unsigned char *sha1);
 extern int parse_tag_buffer(struct tag *item, void *data, unsigned long size);
 extern int parse_tag(struct tag *item);
-extern struct object *deref_tag(struct object *);
+extern struct object *deref_tag(struct object *, const char *, int);
 
 #endif /* TAG_H */

diff --git a/upload-pack.c b/upload-pack.c
index c5eff21..be63132 100644 (file)
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -226,7 +226,7 @@ static int send_ref(const char *refname, const unsigned char *sha1)
                nr_our_refs++;
        }
        if (o->type == tag_type) {
-               o = deref_tag(o);
+               o = deref_tag(o, refname, 0);
                packet_write(1, "%s %s^{}\n", sha1_to_hex(o->sha1), refname);
        }
        return 0;