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 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 }