merge-base.c

   1 #include <stdlib.h>
   2 #include "cache.h"
   3 #include "commit.h"
   4
   5 static struct commit *common_ancestor(struct commit *rev1, struct commit *rev2)
   6 {
   7         struct commit_list *list = NULL;
   8         struct commit_list *result = NULL;
   9
  10         if (rev1 == rev2)
  11                 return rev1;
  12
  13         parse_commit(rev1);
  14         parse_commit(rev2);
  15
  16         rev1->object.flags |= 1;
  17         rev2->object.flags |= 2;
  18         insert_by_date(rev1, &list);
  19         insert_by_date(rev2, &list);
  20
  21         while (list) {
  22                 struct commit *commit = list->item;
  23                 struct commit_list *tmp = list, *parents;
  24                 int flags = commit->object.flags & 3;
  25
  26                 list = list->next;
  27                 free(tmp);
  28                 switch (flags) {
  29                 case 3:
  30                         insert_by_date(commit, &result);
  31                         continue;
  32                 case 0:
  33                         die("git-merge-base: commit without either parent?");
  34                 }
  35                 parents = commit->parents;
  36                 while (parents) {
  37                         struct commit *p = parents->item;
  38                         parents = parents->next;
  39                         if ((p->object.flags & flags) == flags)
  40                                 continue;
  41                         parse_commit(p);
  42                         p->object.flags |= flags;
  43                         insert_by_date(p, &list);
  44                 }
  45         }
  46         if (!result)
  47                 return NULL;
  48         return result->item;
  49 }
  50
  51 int main(int argc, char **argv)
  52 {
  53         struct commit *rev1, *rev2, *ret;
  54         unsigned char rev1key[20], rev2key[20];
  55
  56         if (argc != 3 ||
  57             get_sha1(argv[1], rev1key) ||
  58             get_sha1(argv[2], rev2key)) {
  59                 usage("git-merge-base <commit-id> <commit-id>");
  60         }
  61         rev1 = lookup_commit_reference(rev1key);
  62         rev2 = lookup_commit_reference(rev2key);
  63         if (!rev1 || !rev2)
  64                 return 1;
  65         ret = common_ancestor(rev1, rev2);
  66         if (!ret)
  67                 return 1;
  68         printf("%s\n", sha1_to_hex(ret->object.sha1));
  69         return 0;
  70 }