-#include <stdlib.h>
#include "cache.h"
#include "commit.h"
-#define PARENT1 1
-#define PARENT2 2
-#define UNINTERESTING 4
+static int show_all;
-static struct commit *interesting(struct commit_list *list)
+static int merge_base(struct commit *rev1, struct commit *rev2)
{
- while (list) {
- struct commit *commit = list->item;
- list = list->next;
- if (commit->object.flags & UNINTERESTING)
- continue;
- return commit;
- }
- return NULL;
-}
-
-/*
- * A pathological example of how this thing works.
- *
- * Suppose we had this commit graph, where chronologically
- * the timestamp on the commit are A <= B <= C <= D <= E <= F
- * and we are trying to figure out the merge base for E and F
- * commits.
- *
- * F
- * / \
- * E A D
- * \ / /
- * B /
- * \ /
- * C
- *
- * First we push E and F to list to be processed. E gets bit 1
- * and F gets bit 2. The list becomes:
- *
- * list=F(2) E(1), result=empty
- *
- * Then we pop F, the newest commit, from the list. Its flag is 2.
- * We scan its parents, mark them reachable from the side that F is
- * reachable from, and push them to the list:
- *
- * list=E(1) D(2) A(2), result=empty
- *
- * Next pop E and do the same.
- *
- * list=D(2) B(1) A(2), result=empty
- *
- * Next pop D and do the same.
- *
- * list=C(2) B(1) A(2), result=empty
- *
- * Next pop C and do the same.
- *
- * list=B(1) A(2), result=empty
- *
- * Now it is B's turn. We mark its parent, C, reachable from B's side,
- * and push it to the list:
- *
- * list=C(3) A(2), result=empty
- *
- * Now pop C and notice it has flags==3. It is placed on the result list,
- * and the list now contains:
- *
- * list=A(2), result=C(3)
- *
- * We pop A and do the same.
- *
- * list=B(3), result=C(3)
- *
- * Next, we pop B and something very interesting happens. It has flags==3
- * so it is also placed on the result list, and its parents are marked
- * uninteresting, retroactively, and placed back on the list:
- *
- * list=C(7), result=C(7) B(3)
- *
- * 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.
- */
-
-static struct commit *common_ancestor(struct commit *rev1, struct commit *rev2)
-{
- struct commit_list *list = NULL;
- struct commit_list *result = NULL;
-
- if (rev1 == rev2)
- return rev1;
-
- parse_commit(rev1);
- parse_commit(rev2);
-
- rev1->object.flags |= 1;
- rev2->object.flags |= 2;
- insert_by_date(rev1, &list);
- insert_by_date(rev2, &list);
+ struct commit_list *result = get_merge_bases(rev1, rev2, 0);
- while (interesting(list)) {
- struct commit *commit = list->item;
- struct commit_list *tmp = list, *parents;
- int flags = commit->object.flags & 7;
-
- list = list->next;
- free(tmp);
- if (flags == 3) {
- insert_by_date(commit, &result);
+ if (!result)
+ return 1;
- /* Mark children of a found merge uninteresting */
- flags |= UNINTERESTING;
- }
- parents = commit->parents;
- while (parents) {
- struct commit *p = parents->item;
- parents = parents->next;
- if ((p->object.flags & flags) == flags)
- continue;
- parse_commit(p);
- p->object.flags |= flags;
- insert_by_date(p, &list);
- }
+ while (result) {
+ printf("%s\n", sha1_to_hex(result->item->object.sha1));
+ if (!show_all)
+ return 0;
+ result = result->next;
}
- return interesting(result);
+
+ 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);
}