merge(3p/git): Merge git subtree at v2.29.2 r/1890

This also bumps the stable nixpkgs to 20.09 as of 2020-11-21, because
there is some breakage in the git build related to the netrc
credentials helper which someone has taken care of in nixpkgs.

The stable channel is not used for anything other than git, so this
should be fine.

Change-Id: I3575a19dab09e1e9556cf8231d717de9890484fb

1 files changed, 26 insertions, 4 deletions

diff --git a/third_party/git/tag.c b/third_party/git/tag.c
index 5db870edb9..1ed2684e45 100644
--- a/third_party/git/tag.c
+++ b/third_party/git/tag.c
@@ -103,7 +103,7 @@ struct tag *lookup_tag(struct repository *r, const struct object_id *oid)
 	struct object *obj = lookup_object(r, oid);
 	if (!obj)
 		return create_object(r, oid, alloc_tag_node(r));
-	return object_as_type(r, obj, OBJ_TAG, 0);
+	return object_as_type(obj, OBJ_TAG, 0);
 }
 
 static timestamp_t parse_tag_date(const char *buf, const char *tail)
@@ -141,7 +141,16 @@ int parse_tag_buffer(struct repository *r, struct tag *item, const void *data, u
 
 	if (item->object.parsed)
 		return 0;
-	item->object.parsed = 1;
+
+	if (item->tag) {
+		/*
+		 * Presumably left over from a previous failed parse;
+		 * clear it out in preparation for re-parsing (we'll probably
+		 * hit the same error, which lets us tell our current caller
+		 * about the problem).
+		 */
+		FREE_AND_NULL(item->tag);
+	}
 
 	if (size < the_hash_algo->hexsz + 24)
 		return -1;
@@ -167,10 +176,15 @@ int parse_tag_buffer(struct repository *r, struct tag *item, const void *data, u
 	} else if (!strcmp(type, tag_type)) {
 		item->tagged = (struct object *)lookup_tag(r, &oid);
 	} else {
-		error("Unknown type %s", type);
-		item->tagged = NULL;
+		return error("unknown tag type '%s' in %s",
+			     type, oid_to_hex(&item->object.oid));
 	}
 
+	if (!item->tagged)
+		return error("bad tag pointer to %s in %s",
+			     oid_to_hex(&oid),
+			     oid_to_hex(&item->object.oid));
+
 	if (bufptr + 4 < tail && starts_with(bufptr, "tag "))
 		; 		/* good */
 	else
@@ -187,6 +201,7 @@ int parse_tag_buffer(struct repository *r, struct tag *item, const void *data, u
 	else
 		item->date = 0;
 
+	item->object.parsed = 1;
 	return 0;
 }
 
@@ -212,3 +227,10 @@ int parse_tag(struct tag *item)
 	free(data);
 	return ret;
 }
+
+struct object_id *get_tagged_oid(struct tag *tag)
+{
+	if (!tag->tagged)
+		die("bad tag");
+	return &tag->tagged->oid;
+}