Add "look up parent" logic for the simple names.

It uses the jit syntax, at least for now. 0-xxxx is the first parent of xxxx,
while 1-xxxx is the second, and so on. You can use just "-xxxx" for the first
parent, but a lot of commands will think that the initial '-' implies a
command line flag.

diff --git a/sha1_file.c b/sha1_file.c
index d91e072..e1ee0ad 100644 (file)
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -60,17 +60,74 @@ int get_sha1_file(const char *path, unsigned char *result)
        return get_sha1_hex(buffer, result);
 }
 
+static int get_parent(int index, const char *str, unsigned char *result)
+{
+       unsigned char sha1[20];
+       char *buffer;
+       unsigned long size, offset;
+       int ret;
+
+       if (get_sha1(str, sha1) < 0)
+               return -1;
+       buffer = read_object_with_reference(sha1, "commit", &size, NULL);
+       if (!buffer)
+               return -1;
+       ret = -1;
+       offset = 46;
+       for (;;) {
+               if (offset + 48 > size)
+                       break;
+               if (memcmp(buffer + offset, "parent ", 7))
+                       break;
+               if (index > 0) {
+                       offset += 48;
+                       index--;
+                       continue;
+               }
+               ret = get_sha1_hex(buffer + offset + 7, result);
+               break;
+       }
+       free(buffer);
+       return ret;     
+}
+
 int get_sha1(const char *str, unsigned char *sha1)
 {
        static char pathname[PATH_MAX];
+       static const char *prefix[] = {
+               "",
+               "refs",
+               "refs/tags",
+               "refs/heads",
+               "refs/snap",
+               NULL
+       };
+       const char *gitdir;
+       const char **p;
 
        if (!get_sha1_hex(str, sha1))
                return 0;
-       if (!get_sha1_file(str, sha1))
-               return 0;
-       snprintf(pathname, sizeof(pathname), ".git/%s", str);
-       if (!get_sha1_file(pathname, sha1))
-               return 0;
+
+       switch (*str) {
+       case '/':
+               if (!get_sha1_file(str, sha1))
+                       return 0;
+               break;
+       case '-':
+               return get_parent(0, str+1, sha1);
+       case '0' ... '9':
+               if (str[1] == '-')
+                       return get_parent(*str - '0', str+2, sha1);
+               break;
+       }
+
+       gitdir = ".git";
+       for (p = prefix; *p; p++) {
+               snprintf(pathname, sizeof(pathname), "%s/%s/%s", gitdir, *p, str);
+               if (!get_sha1_file(pathname, sha1))
+                       return 0;
+       }
+
        return -1;
 }