+static int dotdot_missing(const char *arg, char *dotdot,
+ struct rev_info *revs, int symmetric)
+{
+ if (revs->ignore_missing)
+ return 0;
+ /* de-munge so we report the full argument */
+ *dotdot = '.';
+ die(symmetric
+ ? "Invalid symmetric difference expression %s"
+ : "Invalid revision range %s", arg);
+}
+
+static int handle_dotdot_1(const char *arg, char *dotdot,
+ struct rev_info *revs, int flags,
+ int cant_be_filename,
+ struct object_context *a_oc,
+ struct object_context *b_oc)
+{
+ const char *a_name, *b_name;
+ struct object_id a_oid, b_oid;
+ struct object *a_obj, *b_obj;
+ unsigned int a_flags, b_flags;
+ int symmetric = 0;
+ unsigned int flags_exclude = flags ^ (UNINTERESTING | BOTTOM);
+ unsigned int oc_flags = GET_SHA1_COMMITTISH | GET_SHA1_RECORD_PATH;
+
+ a_name = arg;
+ if (!*a_name)
+ a_name = "HEAD";
+
+ b_name = dotdot + 2;
+ if (*b_name == '.') {
+ symmetric = 1;
+ b_name++;
+ }
+ if (!*b_name)
+ b_name = "HEAD";
+
+ if (get_sha1_with_context(a_name, oc_flags, a_oid.hash, a_oc) ||
+ get_sha1_with_context(b_name, oc_flags, b_oid.hash, b_oc))
+ return -1;
+
+ if (!cant_be_filename) {
+ *dotdot = '.';
+ verify_non_filename(revs->prefix, arg);
+ *dotdot = '\0';
+ }
+
+ a_obj = parse_object(a_oid.hash);
+ b_obj = parse_object(b_oid.hash);
+ if (!a_obj || !b_obj)
+ return dotdot_missing(arg, dotdot, revs, symmetric);
+
+ if (!symmetric) {
+ /* just A..B */
+ b_flags = flags;
+ a_flags = flags_exclude;
+ } else {
+ /* A...B -- find merge bases between the two */
+ struct commit *a, *b;
+ struct commit_list *exclude;
+
+ a = lookup_commit_reference(a_obj->oid.hash);
+ b = lookup_commit_reference(b_obj->oid.hash);
+ if (!a || !b)
+ return dotdot_missing(arg, dotdot, revs, symmetric);
+
+ exclude = get_merge_bases(a, b);
+ add_rev_cmdline_list(revs, exclude, REV_CMD_MERGE_BASE,
+ flags_exclude);
+ add_pending_commit_list(revs, exclude, flags_exclude);
+ free_commit_list(exclude);
+
+ b_flags = flags;
+ a_flags = flags | SYMMETRIC_LEFT;
+ }
+
+ a_obj->flags |= a_flags;
+ b_obj->flags |= b_flags;
+ add_rev_cmdline(revs, a_obj, a_name, REV_CMD_LEFT, a_flags);
+ add_rev_cmdline(revs, b_obj, b_name, REV_CMD_RIGHT, b_flags);
+ add_pending_object_with_path(revs, a_obj, a_name, a_oc->mode, a_oc->path);
+ add_pending_object_with_path(revs, b_obj, b_name, b_oc->mode, b_oc->path);
+ return 0;
+}
+
+static int handle_dotdot(const char *arg,
+ struct rev_info *revs, int flags,
+ int cant_be_filename)
+{
+ struct object_context a_oc, b_oc;
+ char *dotdot = strstr(arg, "..");
+ int ret;
+
+ if (!dotdot)
+ return -1;
+
+ memset(&a_oc, 0, sizeof(a_oc));
+ memset(&b_oc, 0, sizeof(b_oc));
+
+ *dotdot = '\0';
+ ret = handle_dotdot_1(arg, dotdot, revs, flags, cant_be_filename,
+ &a_oc, &b_oc);
+ *dotdot = '.';
+
+ free(a_oc.path);
+ free(b_oc.path);
+
+ return ret;
+}
+