merge-base.c

   1 #include <stdlib.h>
   2 #include "cache.h"
   3 #include "commit.h"
   4
   5 #define PARENT1 1
   6 #define PARENT2 2
   7 #define UNINTERESTING 4
   8
   9 static int interesting(struct commit_list *list)
  10 {
  11         while (list) {
  12                 struct commit *commit = list->item;
  13                 list = list->next;
  14                 if (commit->object.flags & UNINTERESTING)
  15                         continue;
  16                 return 1;
  17         }
  18         return 0;
  19 }
  20
  21 static struct commit *common_ancestor(struct commit *rev1, struct commit *rev2)
  22 {
  23         struct commit_list *list = NULL;
  24         struct commit_list *result = NULL;
  25
  26         if (rev1 == rev2)
  27                 return rev1;
  28
  29         parse_commit(rev1);
  30         parse_commit(rev2);
  31
  32         rev1->object.flags |= 1;
  33         rev2->object.flags |= 2;
  34         insert_by_date(rev1, &list);
  35         insert_by_date(rev2, &list);
  36
  37         while (interesting(list)) {
  38                 struct commit *commit = list->item;
  39                 struct commit_list *tmp = list, *parents;
  40                 int flags = commit->object.flags & 7;
  41
  42                 list = list->next;
  43                 free(tmp);
  44                 if (flags == 3) {
  45                         insert_by_date(commit, &result);
  46
  47                         /* Mark children of a found merge uninteresting */
  48                         flags |= UNINTERESTING;
  49                 }
  50                 parents = commit->parents;
  51                 while (parents) {
  52                         struct commit *p = parents->item;
  53                         parents = parents->next;
  54                         if ((p->object.flags & flags) == flags)
  55                                 continue;
  56                         parse_commit(p);
  57                         p->object.flags |= flags;
  58                         insert_by_date(p, &list);
  59                 }
  60         }
  61         if (!result)
  62                 return NULL;
  63         return result->item;
  64 }
  65
  66 int main(int argc, char **argv)
  67 {
  68         struct commit *rev1, *rev2, *ret;
  69         unsigned char rev1key[20], rev2key[20];
  70
  71         if (argc != 3 ||
  72             get_sha1(argv[1], rev1key) ||
  73             get_sha1(argv[2], rev2key)) {
  74                 usage("git-merge-base <commit-id> <commit-id>");
  75         }
  76         rev1 = lookup_commit_reference(rev1key);
  77         rev2 = lookup_commit_reference(rev2key);
  78         if (!rev1 || !rev2)
  79                 return 1;
  80         ret = common_ancestor(rev1, rev2);
  81         if (!ret)
  82                 return 1;
  83         printf("%s\n", sha1_to_hex(ret->object.sha1));
  84         return 0;
  85 }