commit: add "lookup_commit_reference()" helper function

It's pretty much the same as "lookup_commit()", but it will take
tags too, and look up the commit (if any) associated with them.

diff --git a/commit.c b/commit.c
index 706c7cb..e830564 100644 (file)
--- a/commit.c
+++ b/commit.c
@@ -1,3 +1,4 @@
+#include "tag.h"
 #include "commit.h"
 #include "cache.h"
 #include <string.h>
@@ -5,6 +6,27 @@
 
 const char *commit_type = "commit";
 
+static struct commit *check_commit(struct object *obj, unsigned char *sha1)
+{
+       if (obj->type != commit_type) {
+               error("Object %s is a %s, not a commit", 
+                     sha1_to_hex(sha1), obj->type);
+               return NULL;
+       }
+       return (struct commit *) obj;
+}
+
+struct commit *lookup_commit_reference(unsigned char *sha1)
+{
+       struct object *obj = parse_object(sha1);
+
+       if (!obj)
+               return NULL;
+       if (obj->type == tag_type)
+               obj = ((struct tag *)obj)->tagged;
+       return check_commit(obj, sha1);
+}
+
 struct commit *lookup_commit(unsigned char *sha1)
 {
        struct object *obj = lookup_object(sha1);
@@ -15,12 +37,7 @@ struct commit *lookup_commit(unsigned char *sha1)
                ret->object.type = commit_type;
                return ret;
        }
-       if (obj->type != commit_type) {
-               error("Object %s is a %s, not a commit", 
-                     sha1_to_hex(sha1), obj->type);
-               return NULL;
-       }
-       return (struct commit *) obj;
+       return check_commit(obj, sha1);
 }
 
 static unsigned long parse_commit_date(const char *buf)

diff --git a/commit.h b/commit.h
index ce0b436..620e936 100644 (file)
--- a/commit.h
+++ b/commit.h
@@ -19,6 +19,7 @@ struct commit {
 extern const char *commit_type;
 
 struct commit *lookup_commit(unsigned char *sha1);
+struct commit *lookup_commit_reference(unsigned char *sha1);
 
 int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size);