Ahh, the heady days of 0.99 patchfiles
[git.git] / merge-base.c
1 #include <stdlib.h>
2 #include "cache.h"
3 #include "commit.h"
4
5 static struct commit *process_list(struct commit_list **list_p, int this_mark,
6                                    int other_mark)
7 {
8         struct commit *item = (*list_p)->item;
9
10         if (item->object.flags & other_mark) {
11                 return item;
12         } else {
13                 pop_most_recent_commit(list_p, this_mark);
14         }
15         return NULL;
16 }
17
18 static struct commit *common_ancestor(struct commit *rev1, struct commit *rev2)
19 {
20         struct commit_list *rev1list = NULL;
21         struct commit_list *rev2list = NULL;
22
23         commit_list_insert(rev1, &rev1list);
24         rev1->object.flags |= 0x1;
25         commit_list_insert(rev2, &rev2list);
26         rev2->object.flags |= 0x2;
27
28         parse_commit(rev1);
29         parse_commit(rev2);
30
31         while (rev1list || rev2list) {
32                 struct commit *ret;
33                 if (!rev1list) {
34                         // process 2
35                         ret = process_list(&rev2list, 0x2, 0x1);
36                 } else if (!rev2list) {
37                         // process 1
38                         ret = process_list(&rev1list, 0x1, 0x2);
39                 } else if (rev1list->item->date < rev2list->item->date) {
40                         // process 2
41                         ret = process_list(&rev2list, 0x2, 0x1);
42                 } else {
43                         // process 1
44                         ret = process_list(&rev1list, 0x1, 0x2);
45                 }
46                 if (ret) {
47                         free_commit_list(rev1list);
48                         free_commit_list(rev2list);
49                         return ret;
50                 }
51         }
52         return NULL;
53 }
54
55 int main(int argc, char **argv)
56 {
57         struct commit *rev1, *rev2, *ret;
58         unsigned char rev1key[20], rev2key[20];
59
60         if (argc != 3 ||
61             get_sha1(argv[1], rev1key) ||
62             get_sha1(argv[2], rev2key)) {
63                 usage("git-merge-base <commit-id> <commit-id>");
64         }
65         rev1 = lookup_commit_reference(rev1key);
66         rev2 = lookup_commit_reference(rev2key);
67         ret = common_ancestor(rev1, rev2);
68         if (!ret)
69                 return 1;
70         printf("%s\n", sha1_to_hex(ret->object.sha1));
71         return 0;
72 }