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#include <stdlib.h>
#include "cache.h"
#include "commit.h"
#define PARENT1 1
#define PARENT2 2
#define UNINTERESTING 4
static int interesting(struct commit_list *list)
{
while (list) {
struct commit *commit = list->item;
list = list->next;
if (commit->object.flags & UNINTERESTING)
continue;
return 1;
}
return 0;
}
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);
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);
/* 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);
}
}
if (!result)
return NULL;
return result->item;
}
int main(int argc, char **argv)
{
struct commit *rev1, *rev2, *ret;
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>");
}
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;
}
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