1 files changed, 68 insertions, 0 deletions
diff --git a/builtin-merge-base.c b/builtin-merge-base.c
new file mode 100644
index 0000000000..b08da516e4
--- /dev/null
+++ b/builtin-merge-base.c
@@ -0,0 +1,68 @@
+#include "builtin.h"
+#include "cache.h"
+#include "commit.h"
+
+static int show_merge_base(struct commit **rev, int rev_nr, int show_all)
+{
+	struct commit_list *result;
+
+	result = get_merge_bases_many(rev[0], rev_nr - 1, rev + 1, 0);
+
+	if (!result)
+		return 1;
+
+	while (result) {
+		printf("%s\n", sha1_to_hex(result->item->object.sha1));
+		if (!show_all)
+			return 0;
+		result = result->next;
+	}
+
+	return 0;
+}
+
+static const char merge_base_usage[] =
+"git merge-base [--all] <commit-id> <commit-id>...";
+
+static struct commit *get_commit_reference(const char *arg)
+{
+	unsigned char revkey[20];
+	struct commit *r;
+
+	if (get_sha1(arg, revkey))
+		die("Not a valid object name %s", arg);
+	r = lookup_commit_reference(revkey);
+	if (!r)
+		die("Not a valid commit name %s", arg);
+
+	return r;
+}
+
+int cmd_merge_base(int argc, const char **argv, const char *prefix)
+{
+	struct commit **rev;
+	int rev_nr = 0;
+	int show_all = 0;
+
+	git_config(git_default_config, NULL);
+
+	while (1 < argc && argv[1][0] == '-') {
+		const 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);
+
+	rev = xmalloc((argc - 1) * sizeof(*rev));
+
+	do {
+		rev[rev_nr++] = get_commit_reference(argv[1]);
+		argc--; argv++;
+	} while (argc > 1);
+
+	return show_merge_base(rev, rev_nr, show_all);
+}