git am: Display some help text when patch is empty

diff --git a/tag.c b/tag.c
index f62bcdd994509323080683ce19c1a4d8241f9dec..85607c219e25d63b0d1f3344649104c60f5b96e2 100644 (file)
--- a/tag.c
+++ b/tag.c
@@ -9,7 +9,10 @@ const char *tag_type = "tag";
 struct object *deref_tag(struct object *o, const char *warn, int warnlen)
 {
        while (o && o->type == OBJ_TAG)
-               o = parse_object(((struct tag *)o)->tagged->sha1);
+               if (((struct tag *)o)->tagged)
+                       o = parse_object(((struct tag *)o)->tagged->sha1);
+               else
+                       o = NULL;
        if (!o && warn) {
                if (!warnlen)
                        warnlen = strlen(warn);
@@ -33,42 +36,50 @@ struct tag *lookup_tag(const unsigned char *sha1)
         return (struct tag *) obj;
 }
 
+static unsigned long parse_tag_date(const char *buf, const char *tail)
+{
+       const char *dateptr;
+
+       while (buf < tail && *buf++ != '>')
+               /* nada */;
+       if (buf >= tail)
+               return 0;
+       dateptr = buf;
+       while (buf < tail && *buf++ != '\n')
+               /* nada */;
+       if (buf >= tail)
+               return 0;
+       /* dateptr < buf && buf[-1] == '\n', so strtoul will stop at buf-1 */
+       return strtoul(dateptr, NULL, 10);
+}
+
 int parse_tag_buffer(struct tag *item, void *data, unsigned long size)
 {
-       int typelen, taglen;
        unsigned char sha1[20];
-       const char *type_line, *tag_line, *sig_line;
        char type[20];
+       const char *bufptr = data;
+       const char *tail = bufptr + size;
+       const char *nl;
 
-        if (item->object.parsed)
-                return 0;
-        item->object.parsed = 1;
+       if (item->object.parsed)
+               return 0;
+       item->object.parsed = 1;
 
        if (size < 64)
                return -1;
-       if (memcmp("object ", data, 7) || get_sha1_hex((char *) data + 7, sha1))
+       if (memcmp("object ", bufptr, 7) || get_sha1_hex(bufptr + 7, sha1) || bufptr[47] != '\n')
                return -1;
+       bufptr += 48; /* "object " + sha1 + "\n" */
 
-       type_line = (char *) data + 48;
-       if (memcmp("\ntype ", type_line-1, 6))
+       if (prefixcmp(bufptr, "type "))
                return -1;
-
-       tag_line = strchr(type_line, '\n');
-       if (!tag_line || memcmp("tag ", ++tag_line, 4))
+       bufptr += 5;
+       nl = memchr(bufptr, '\n', tail - bufptr);
+       if (!nl || sizeof(type) <= (nl - bufptr))
                return -1;
-
-       sig_line = strchr(tag_line, '\n');
-       if (!sig_line)
-               return -1;
-       sig_line++;
-
-       typelen = tag_line - type_line - strlen("type \n");
-       if (typelen >= 20)
-               return -1;
-       memcpy(type, type_line + 5, typelen);
-       type[typelen] = '\0';
-       taglen = sig_line - tag_line - strlen("tag \n");
-       item->tag = xmemdupz(tag_line + 4, taglen);
+       strncpy(type, bufptr, nl - bufptr);
+       type[nl - bufptr] = '\0';
+       bufptr = nl + 1;
 
        if (!strcmp(type, blob_type)) {
                item->tagged = &lookup_blob(sha1)->object;
@@ -83,11 +94,19 @@ int parse_tag_buffer(struct tag *item, void *data, unsigned long size)
                item->tagged = NULL;
        }
 
-       if (item->tagged && track_object_refs) {
-               struct object_refs *refs = alloc_object_refs(1);
-               refs->ref[0] = item->tagged;
-               set_object_refs(&item->object, refs);
-       }
+       if (prefixcmp(bufptr, "tag "))
+               return -1;
+       bufptr += 4;
+       nl = memchr(bufptr, '\n', tail - bufptr);
+       if (!nl)
+               return -1;
+       item->tag = xmemdupz(bufptr, nl - bufptr);
+       bufptr = nl + 1;
+
+       if (!prefixcmp(bufptr, "tagger "))
+               item->date = parse_tag_date(bufptr, tail);
+       else
+               item->date = 0;
 
        return 0;
 }