X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=merge-base.c;h=4856ca01c33896843c366f3fb5edadd2ea3ced37;hb=fb6a9f93d39e4e5fdb83673a927f71a34e9fb7c0;hp=923256c821582f38daffed4fb0df2a97fe66d74b;hpb=9d34c29db39bdb5c2443475dd6a24cfc5c2c9e37;p=git.git

diff --git a/merge-base.c b/merge-base.c
index 923256c8..4856ca01 100644
--- a/merge-base.c
+++ b/merge-base.c
@@ -80,15 +80,103 @@ static struct commit *interesting(struct commit_list *list)
  * Now, list does not have any interesting commit.  So we find the newest
  * commit from the result list that is not marked uninteresting.  Which is
  * commit B.
+ *
+ *
+ * Another pathological example how this thing used to fail to mark an
+ * ancestor of a merge base as UNINTERESTING before we introduced the
+ * postprocessing phase (mark_reachable_commits).
+ *
+ *		  2
+ *		  H
+ *	    1    / \
+ *	    G   A   \
+ *	    |\ /     \ 
+ *	    | B       \
+ *	    |  \       \
+ *	     \  C       F
+ *	      \  \     / 
+ *	       \  D   /   
+ *		\ |  /
+ *		 \| /
+ *		  E
+ *
+ *	 list			A B C D E F G H
+ *	 G1 H2			- - - - - - 1 2
+ *	 H2 E1 B1		- 1 - - 1 - 1 2
+ *	 F2 E1 B1 A2		2 1 - - 1 2 1 2
+ *	 E3 B1 A2		2 1 - - 3 2 1 2
+ *	 B1 A2			2 1 - - 3 2 1 2
+ *	 C1 A2			2 1 1 - 3 2 1 2
+ *	 D1 A2			2 1 1 1 3 2 1 2
+ *	 A2			2 1 1 1 3 2 1 2
+ *	 B3			2 3 1 1 3 2 1 2
+ *	 C7			2 3 7 1 3 2 1 2
+ *
+ * At this point, unfortunately, everybody in the list is
+ * uninteresting, so we fail to complete the following two
+ * steps to fully marking uninteresting commits.
+ *
+ *	 D7			2 3 7 7 3 2 1 2
+ *	 E7			2 3 7 7 7 2 1 2
+ *
+ * and we ended up showing E as an interesting merge base.
+ * The postprocessing phase re-injects C and continues traversal
+ * to contaminate D and E.
  */
 
-static struct commit *common_ancestor(struct commit *rev1, struct commit *rev2)
+static int show_all = 0;
+
+static void mark_reachable_commits(struct commit_list *result,
+				   struct commit_list *list)
+{
+	struct commit_list *tmp;
+
+	/*
+	 * Postprocess to fully contaminate the well.
+	 */
+	for (tmp = result; tmp; tmp = tmp->next) {
+		struct commit *c = tmp->item;
+		/* Reinject uninteresting ones to list,
+		 * so we can scan their parents.
+		 */
+		if (c->object.flags & UNINTERESTING)
+			commit_list_insert(c, &list);
+	}
+	while (list) {
+		struct commit *c = list->item;
+		struct commit_list *parents;
+
+		tmp = list;
+		list = list->next;
+		free(tmp);
+
+		/* Anything taken out of the list is uninteresting, so
+		 * mark all its parents uninteresting.  We do not
+		 * parse new ones (we already parsed all the relevant
+		 * ones).
+		 */
+		parents = c->parents;
+		while (parents) {
+			struct commit *p = parents->item;
+			parents = parents->next;
+			if (!(p->object.flags & UNINTERESTING)) {
+				p->object.flags |= UNINTERESTING;
+				commit_list_insert(p, &list);
+			}
+		}
+	}
+}
+
+static int merge_base(struct commit *rev1, struct commit *rev2)
 {
 	struct commit_list *list = NULL;
 	struct commit_list *result = NULL;
+	struct commit_list *tmp = NULL;
 
-	if (rev1 == rev2)
-		return rev1;
+	if (rev1 == rev2) {
+		printf("%s\n", sha1_to_hex(rev1->object.sha1));
+		return 0;
+	}
 
 	parse_commit(rev1);
 	parse_commit(rev2);
@@ -100,15 +188,16 @@ static struct commit *common_ancestor(struct commit *rev1, struct commit *rev2)
 
 	while (interesting(list)) {
 		struct commit *commit = list->item;
-		struct commit_list *tmp = list, *parents;
+		struct commit_list *parents;
 		int flags = commit->object.flags & 7;
 
+		tmp = list;
 		list = list->next;
 		free(tmp);
 		if (flags == 3) {
 			insert_by_date(commit, &result);
 
-			/* Mark children of a found merge uninteresting */
+			/* Mark parents of a found merge uninteresting */
 			flags |= UNINTERESTING;
 		}
 		parents = commit->parents;
@@ -122,26 +211,54 @@ static struct commit *common_ancestor(struct commit *rev1, struct commit *rev2)
 			insert_by_date(p, &list);
 		}
 	}
-	return interesting(result);
+
+	if (!result)
+		return 1;
+
+	if (result->next && list)
+		mark_reachable_commits(result, list);
+
+	while (result) {
+		struct commit *commit = result->item;
+		result = result->next;
+		if (commit->object.flags & UNINTERESTING)
+			continue;
+		printf("%s\n", sha1_to_hex(commit->object.sha1));
+		if (!show_all)
+			return 0;
+		commit->object.flags |= UNINTERESTING;
+	}
+	return 0;
 }
 
+static const char merge_base_usage[] =
+"git-merge-base [--all] <commit-id> <commit-id>";
+
 int main(int argc, char **argv)
 {
-	struct commit *rev1, *rev2, *ret;
+	struct commit *rev1, *rev2;
 	unsigned char rev1key[20], rev2key[20];
 
-	if (argc != 3 ||
-	    get_sha1(argv[1], rev1key) ||
-	    get_sha1(argv[2], rev2key)) {
-		usage("git-merge-base <commit-id> <commit-id>");
+	setup_git_directory();
+	git_config(git_default_config);
+
+	while (1 < argc && argv[1][0] == '-') {
+		char *arg = argv[1];
+		if (!strcmp(arg, "-a") || !strcmp(arg, "--all"))
+			show_all = 1;
+		else
+			usage(merge_base_usage);
+		argc--; argv++;
 	}
+	if (argc != 3)
+		usage(merge_base_usage);
+	if (get_sha1(argv[1], rev1key))
+		die("Not a valid object name %s", argv[1]);
+	if (get_sha1(argv[2], rev2key))
+		die("Not a valid object name %s", argv[2]);
 	rev1 = lookup_commit_reference(rev1key);
 	rev2 = lookup_commit_reference(rev2key);
 	if (!rev1 || !rev2)
 		return 1;
-	ret = common_ancestor(rev1, rev2);
-	if (!ret)
-		return 1;
-	printf("%s\n", sha1_to_hex(ret->object.sha1));
-	return 0;
+	return merge_base(rev1, rev2);
 }