commit: add "lookup_commit_reference()" helper function

diff --git a/commit.c b/commit.c
index 2502688262819033f5b8ed60a7bef5eed0aa2d6a..e83056406f54495fe8a1090a816c425375858d4d 100644 (file)
--- a/commit.c
+++ b/commit.c
@@ -1,3 +1,4 @@
+#include "tag.h"
 #include "commit.h"
 #include "cache.h"
 #include <string.h>
@@ -5,21 +6,38 @@
 
 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);
        if (!obj) {
-               struct commit *ret = malloc(sizeof(struct commit));
+               struct commit *ret = xmalloc(sizeof(struct commit));
                memset(ret, 0, sizeof(struct commit));
                created_object(sha1, &ret->object);
+               ret->object.type = commit_type;
                return ret;
        }
-       if (obj->parsed && 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)
@@ -40,42 +58,58 @@ static unsigned long parse_commit_date(const char *buf)
        return date;
 }
 
-int parse_commit(struct commit *item)
+int parse_commit_buffer(struct commit *item, void *buffer, unsigned long size)
 {
-       char type[20];
-       void * buffer, *bufptr;
-       unsigned long size;
+       void *bufptr = buffer;
        unsigned char parent[20];
+
        if (item->object.parsed)
                return 0;
        item->object.parsed = 1;
-       buffer = bufptr = read_sha1_file(item->object.sha1, type, &size);
-       if (!buffer)
-               return error("Could not read %s",
-                            sha1_to_hex(item->object.sha1));
-       if (strcmp(type, commit_type))
-               return error("Object %s not a commit",
-                            sha1_to_hex(item->object.sha1));
-       item->object.type = commit_type;
        get_sha1_hex(bufptr + 5, parent);
        item->tree = lookup_tree(parent);
-       add_ref(&item->object, &item->tree->object);
+       if (item->tree)
+               add_ref(&item->object, &item->tree->object);
        bufptr += 46; /* "tree " + "hex sha1" + "\n" */
        while (!memcmp(bufptr, "parent ", 7) &&
               !get_sha1_hex(bufptr + 7, parent)) {
                struct commit *new_parent = lookup_commit(parent);
-               commit_list_insert(new_parent, &item->parents);
-               add_ref(&item->object, &new_parent->object);
+               if (new_parent) {
+                       commit_list_insert(new_parent, &item->parents);
+                       add_ref(&item->object, &new_parent->object);
+               }
                bufptr += 48;
        }
        item->date = parse_commit_date(bufptr);
-       free(buffer);
        return 0;
 }
 
+int parse_commit(struct commit *item)
+{
+       char type[20];
+       void *buffer;
+       unsigned long size;
+       int ret;
+
+       if (item->object.parsed)
+               return 0;
+       buffer = read_sha1_file(item->object.sha1, type, &size);
+       if (!buffer)
+               return error("Could not read %s",
+                            sha1_to_hex(item->object.sha1));
+       if (strcmp(type, commit_type)) {
+               free(buffer);
+               return error("Object %s not a commit",
+                            sha1_to_hex(item->object.sha1));
+       }
+       ret = parse_commit_buffer(item, buffer, size);
+       free(buffer);
+       return ret;
+}
+
 void commit_list_insert(struct commit *item, struct commit_list **list_p)
 {
-       struct commit_list *new_list = malloc(sizeof(struct commit_list));
+       struct commit_list *new_list = xmalloc(sizeof(struct commit_list));
        new_list->item = item;
        new_list->next = *list_p;
        *list_p = new_list;