notes-merge.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "refs.h"
   4 #include "notes-merge.h"
   5
   6 void init_notes_merge_options(struct notes_merge_options *o)
   7 {
   8         memset(o, 0, sizeof(struct notes_merge_options));
   9         o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
  10 }
  11
  12 #define OUTPUT(o, v, ...) \
  13         do { \
  14                 if ((o)->verbosity >= (v)) { \
  15                         printf(__VA_ARGS__); \
  16                         puts(""); \
  17                 } \
  18         } while (0)
  19
  20 int notes_merge(struct notes_merge_options *o,
  21                 unsigned char *result_sha1)
  22 {
  23         unsigned char local_sha1[20], remote_sha1[20];
  24         struct commit *local, *remote;
  25         struct commit_list *bases = NULL;
  26         const unsigned char *base_sha1;
  27         int result = 0;
  28
  29         assert(o->local_ref && o->remote_ref);
  30         hashclr(result_sha1);
  31
  32         trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
  33                o->local_ref, o->remote_ref);
  34
  35         /* Dereference o->local_ref into local_sha1 */
  36         if (!resolve_ref(o->local_ref, local_sha1, 0, NULL))
  37                 die("Failed to resolve local notes ref '%s'", o->local_ref);
  38         else if (!check_ref_format(o->local_ref) && is_null_sha1(local_sha1))
  39                 local = NULL; /* local_sha1 == null_sha1 indicates unborn ref */
  40         else if (!(local = lookup_commit_reference(local_sha1)))
  41                 die("Could not parse local commit %s (%s)",
  42                     sha1_to_hex(local_sha1), o->local_ref);
  43         trace_printf("\tlocal commit: %.7s\n", sha1_to_hex(local_sha1));
  44
  45         /* Dereference o->remote_ref into remote_sha1 */
  46         if (get_sha1(o->remote_ref, remote_sha1)) {
  47                 /*
  48                  * Failed to get remote_sha1. If o->remote_ref looks like an
  49                  * unborn ref, perform the merge using an empty notes tree.
  50                  */
  51                 if (!check_ref_format(o->remote_ref)) {
  52                         hashclr(remote_sha1);
  53                         remote = NULL;
  54                 } else {
  55                         die("Failed to resolve remote notes ref '%s'",
  56                             o->remote_ref);
  57                 }
  58         } else if (!(remote = lookup_commit_reference(remote_sha1))) {
  59                 die("Could not parse remote commit %s (%s)",
  60                     sha1_to_hex(remote_sha1), o->remote_ref);
  61         }
  62         trace_printf("\tremote commit: %.7s\n", sha1_to_hex(remote_sha1));
  63
  64         if (!local && !remote)
  65                 die("Cannot merge empty notes ref (%s) into empty notes ref "
  66                     "(%s)", o->remote_ref, o->local_ref);
  67         if (!local) {
  68                 /* result == remote commit */
  69                 hashcpy(result_sha1, remote_sha1);
  70                 goto found_result;
  71         }
  72         if (!remote) {
  73                 /* result == local commit */
  74                 hashcpy(result_sha1, local_sha1);
  75                 goto found_result;
  76         }
  77         assert(local && remote);
  78
  79         /* Find merge bases */
  80         bases = get_merge_bases(local, remote, 1);
  81         if (!bases) {
  82                 base_sha1 = null_sha1;
  83                 OUTPUT(o, 4, "No merge base found; doing history-less merge");
  84         } else if (!bases->next) {
  85                 base_sha1 = bases->item->object.sha1;
  86                 OUTPUT(o, 4, "One merge base found (%.7s)",
  87                        sha1_to_hex(base_sha1));
  88         } else {
  89                 /* TODO: How to handle multiple merge-bases? */
  90                 base_sha1 = bases->item->object.sha1;
  91                 OUTPUT(o, 3, "Multiple merge bases found. Using the first "
  92                        "(%.7s)", sha1_to_hex(base_sha1));
  93         }
  94
  95         OUTPUT(o, 4, "Merging remote commit %.7s into local commit %.7s with "
  96                "merge-base %.7s", sha1_to_hex(remote->object.sha1),
  97                sha1_to_hex(local->object.sha1), sha1_to_hex(base_sha1));
  98
  99         if (!hashcmp(remote->object.sha1, base_sha1)) {
 100                 /* Already merged; result == local commit */
 101                 OUTPUT(o, 2, "Already up-to-date!");
 102                 hashcpy(result_sha1, local->object.sha1);
 103                 goto found_result;
 104         }
 105         if (!hashcmp(local->object.sha1, base_sha1)) {
 106                 /* Fast-forward; result == remote commit */
 107                 OUTPUT(o, 2, "Fast-forward");
 108                 hashcpy(result_sha1, remote->object.sha1);
 109                 goto found_result;
 110         }
 111
 112         /* TODO: */
 113         result = error("notes_merge() cannot yet handle real merges.");
 114
 115 found_result:
 116         free_commit_list(bases);
 117         trace_printf("notes_merge(): result = %i, result_sha1 = %.7s\n",
 118                result, sha1_to_hex(result_sha1));
 119         return result;
 120 }