git.oblomov.eu Git - git/blob - notes-merge.c

   1 #include "cache.h"
   2 #include "commit.h"
   3 #include "refs.h"
   4 #include "diff.h"
   5 #include "diffcore.h"
   6 #include "notes.h"
   7 #include "notes-merge.h"
   8
   9 struct notes_merge_pair {
  10         unsigned char obj[20], base[20], local[20], remote[20];
  11 };
  12
  13 void init_notes_merge_options(struct notes_merge_options *o)
  14 {
  15         memset(o, 0, sizeof(struct notes_merge_options));
  16         o->verbosity = NOTES_MERGE_VERBOSITY_DEFAULT;
  17 }
  18
  19 #define OUTPUT(o, v, ...) \
  20         do { \
  21                 if ((o)->verbosity >= (v)) { \
  22                         printf(__VA_ARGS__); \
  23                         puts(""); \
  24                 } \
  25         } while (0)
  26
  27 static int path_to_sha1(const char *path, unsigned char *sha1)
  28 {
  29         char hex_sha1[40];
  30         int i = 0;
  31         while (*path && i < 40) {
  32                 if (*path != '/')
  33                         hex_sha1[i++] = *path;
  34                 path++;
  35         }
  36         if (*path || i != 40)
  37                 return -1;
  38         return get_sha1_hex(hex_sha1, sha1);
  39 }
  40
  41 static int verify_notes_filepair(struct diff_filepair *p, unsigned char *sha1)
  42 {
  43         switch (p->status) {
  44         case DIFF_STATUS_MODIFIED:
  45                 assert(p->one->mode == p->two->mode);
  46                 assert(!is_null_sha1(p->one->sha1));
  47                 assert(!is_null_sha1(p->two->sha1));
  48                 break;
  49         case DIFF_STATUS_ADDED:
  50                 assert(is_null_sha1(p->one->sha1));
  51                 break;
  52         case DIFF_STATUS_DELETED:
  53                 assert(is_null_sha1(p->two->sha1));
  54                 break;
  55         default:
  56                 return -1;
  57         }
  58         assert(!strcmp(p->one->path, p->two->path));
  59         return path_to_sha1(p->one->path, sha1);
  60 }
  61
  62 static struct notes_merge_pair *find_notes_merge_pair_pos(
  63                 struct notes_merge_pair *list, int len, unsigned char *obj,
  64                 int insert_new, int *occupied)
  65 {
  66         /*
  67          * Both diff_tree_remote() and diff_tree_local() tend to process
  68          * merge_pairs in ascending order. Therefore, cache last returned
  69          * index, and search sequentially from there until the appropriate
  70          * position is found.
  71          *
  72          * Since inserts only happen from diff_tree_remote() (which mainly
  73          * _appends_), we don't care that inserting into the middle of the
  74          * list is expensive (using memmove()).
  75          */
  76         static int last_index;
  77         int i = last_index < len ? last_index : len - 1;
  78         int prev_cmp = 0, cmp = -1;
  79         while (i >= 0 && i < len) {
  80                 cmp = hashcmp(obj, list[i].obj);
  81                 if (!cmp) /* obj belongs @ i */
  82                         break;
  83                 else if (cmp < 0 && prev_cmp <= 0) /* obj belongs < i */
  84                         i--;
  85                 else if (cmp < 0) /* obj belongs between i-1 and i */
  86                         break;
  87                 else if (cmp > 0 && prev_cmp >= 0) /* obj belongs > i */
  88                         i++;
  89                 else /* if (cmp > 0) */ { /* obj belongs between i and i+1 */
  90                         i++;
  91                         break;
  92                 }
  93                 prev_cmp = cmp;
  94         }
  95         if (i < 0)
  96                 i = 0;
  97         /* obj belongs at, or immediately preceding, index i (0 <= i <= len) */
  98
  99         if (!cmp)
 100                 *occupied = 1;
 101         else {
 102                 *occupied = 0;
 103                 if (insert_new && i < len) {
 104                         memmove(list + i + 1, list + i,
 105                                 (len - i) * sizeof(struct notes_merge_pair));
 106                         memset(list + i, 0, sizeof(struct notes_merge_pair));
 107                 }
 108         }
 109         last_index = i;
 110         return list + i;
 111 }
 112
 113 static unsigned char uninitialized[20] =
 114         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff" \
 115         "\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff";
 116
 117 static struct notes_merge_pair *diff_tree_remote(struct notes_merge_options *o,
 118                                                  const unsigned char *base,
 119                                                  const unsigned char *remote,
 120                                                  int *num_changes)
 121 {
 122         struct diff_options opt;
 123         struct notes_merge_pair *changes;
 124         int i, len = 0;
 125
 126         trace_printf("\tdiff_tree_remote(base = %.7s, remote = %.7s)\n",
 127                sha1_to_hex(base), sha1_to_hex(remote));
 128
 129         diff_setup(&opt);
 130         DIFF_OPT_SET(&opt, RECURSIVE);
 131         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 132         if (diff_setup_done(&opt) < 0)
 133                 die("diff_setup_done failed");
 134         diff_tree_sha1(base, remote, "", &opt);
 135         diffcore_std(&opt);
 136
 137         changes = xcalloc(diff_queued_diff.nr, sizeof(struct notes_merge_pair));
 138
 139         for (i = 0; i < diff_queued_diff.nr; i++) {
 140                 struct diff_filepair *p = diff_queued_diff.queue[i];
 141                 struct notes_merge_pair *mp;
 142                 int occupied;
 143                 unsigned char obj[20];
 144
 145                 if (verify_notes_filepair(p, obj)) {
 146                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 147                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 148                                p->status, sha1_to_hex(p->one->sha1),
 149                                sha1_to_hex(p->two->sha1));
 150                         continue;
 151                 }
 152                 mp = find_notes_merge_pair_pos(changes, len, obj, 1, &occupied);
 153                 if (occupied) {
 154                         /* We've found an addition/deletion pair */
 155                         assert(!hashcmp(mp->obj, obj));
 156                         if (is_null_sha1(p->one->sha1)) { /* addition */
 157                                 assert(is_null_sha1(mp->remote));
 158                                 hashcpy(mp->remote, p->two->sha1);
 159                         } else if (is_null_sha1(p->two->sha1)) { /* deletion */
 160                                 assert(is_null_sha1(mp->base));
 161                                 hashcpy(mp->base, p->one->sha1);
 162                         } else
 163                                 assert(!"Invalid existing change recorded");
 164                 } else {
 165                         hashcpy(mp->obj, obj);
 166                         hashcpy(mp->base, p->one->sha1);
 167                         hashcpy(mp->local, uninitialized);
 168                         hashcpy(mp->remote, p->two->sha1);
 169                         len++;
 170                 }
 171                 trace_printf("\t\tStored remote change for %s: %.7s -> %.7s\n",
 172                        sha1_to_hex(mp->obj), sha1_to_hex(mp->base),
 173                        sha1_to_hex(mp->remote));
 174         }
 175         diff_flush(&opt);
 176         diff_tree_release_paths(&opt);
 177
 178         *num_changes = len;
 179         return changes;
 180 }
 181
 182 static void diff_tree_local(struct notes_merge_options *o,
 183                             struct notes_merge_pair *changes, int len,
 184                             const unsigned char *base,
 185                             const unsigned char *local)
 186 {
 187         struct diff_options opt;
 188         int i;
 189
 190         trace_printf("\tdiff_tree_local(len = %i, base = %.7s, local = %.7s)\n",
 191                len, sha1_to_hex(base), sha1_to_hex(local));
 192
 193         diff_setup(&opt);
 194         DIFF_OPT_SET(&opt, RECURSIVE);
 195         opt.output_format = DIFF_FORMAT_NO_OUTPUT;
 196         if (diff_setup_done(&opt) < 0)
 197                 die("diff_setup_done failed");
 198         diff_tree_sha1(base, local, "", &opt);
 199         diffcore_std(&opt);
 200
 201         for (i = 0; i < diff_queued_diff.nr; i++) {
 202                 struct diff_filepair *p = diff_queued_diff.queue[i];
 203                 struct notes_merge_pair *mp;
 204                 int match;
 205                 unsigned char obj[20];
 206
 207                 if (verify_notes_filepair(p, obj)) {
 208                         trace_printf("\t\tCannot merge entry '%s' (%c): "
 209                                "%.7s -> %.7s. Skipping!\n", p->one->path,
 210                                p->status, sha1_to_hex(p->one->sha1),
 211                                sha1_to_hex(p->two->sha1));
 212                         continue;
 213                 }
 214                 mp = find_notes_merge_pair_pos(changes, len, obj, 0, &match);
 215                 if (!match) {
 216                         trace_printf("\t\tIgnoring local-only change for %s: "
 217                                "%.7s -> %.7s\n", sha1_to_hex(obj),
 218                                sha1_to_hex(p->one->sha1),
 219                                sha1_to_hex(p->two->sha1));
 220                         continue;
 221                 }
 222
 223                 assert(!hashcmp(mp->obj, obj));
 224                 if (is_null_sha1(p->two->sha1)) { /* deletion */
 225                         /*
 226                          * Either this is a true deletion (1), or it is part
 227                          * of an A/D pair (2), or D/A pair (3):
 228                          *
 229                          * (1) mp->local is uninitialized; set it to null_sha1
 230                          * (2) mp->local is not uninitialized; don't touch it
 231                          * (3) mp->local is uninitialized; set it to null_sha1
 232                          *     (will be overwritten by following addition)
 233                          */
 234                         if (!hashcmp(mp->local, uninitialized))
 235                                 hashclr(mp->local);
 236                 } else if (is_null_sha1(p->one->sha1)) { /* addition */
 237                         /*
 238                          * Either this is a true addition (1), or it is part
 239                          * of an A/D pair (2), or D/A pair (3):
 240                          *
 241                          * (1) mp->local is uninitialized; set to p->two->sha1
 242                          * (2) mp->local is uninitialized; set to p->two->sha1
 243                          * (3) mp->local is null_sha1;     set to p->two->sha1
 244                          */
 245                         assert(is_null_sha1(mp->local) ||
 246                                !hashcmp(mp->local, uninitialized));
 247                         hashcpy(mp->local, p->two->sha1);
 248                 } else { /* modification */
 249                         /*
 250                          * This is a true modification. p->one->sha1 shall
 251                          * match mp->base, and mp->local shall be uninitialized.
 252                          * Set mp->local to p->two->sha1.
 253                          */
 254                         assert(!hashcmp(p->one->sha1, mp->base));
 255                         assert(!hashcmp(mp->local, uninitialized));
 256                         hashcpy(mp->local, p->two->sha1);
 257                 }
 258                 trace_printf("\t\tStored local change for %s: %.7s -> %.7s\n",
 259                        sha1_to_hex(mp->obj), sha1_to_hex(mp->base),
 260                        sha1_to_hex(mp->local));
 261         }
 262         diff_flush(&opt);
 263         diff_tree_release_paths(&opt);
 264 }
 265
 266 static int merge_changes(struct notes_merge_options *o,
 267                          struct notes_merge_pair *changes, int *num_changes,
 268                          struct notes_tree *t)
 269 {
 270         int i, conflicts = 0;
 271
 272         trace_printf("\tmerge_changes(num_changes = %i)\n", *num_changes);
 273         for (i = 0; i < *num_changes; i++) {
 274                 struct notes_merge_pair *p = changes + i;
 275                 trace_printf("\t\t%.7s: %.7s -> %.7s/%.7s\n",
 276                        sha1_to_hex(p->obj), sha1_to_hex(p->base),
 277                        sha1_to_hex(p->local), sha1_to_hex(p->remote));
 278
 279                 if (!hashcmp(p->base, p->remote)) {
 280                         /* no remote change; nothing to do */
 281                         trace_printf("\t\t\tskipping (no remote change)\n");
 282                 } else if (!hashcmp(p->local, p->remote)) {
 283                         /* same change in local and remote; nothing to do */
 284                         trace_printf("\t\t\tskipping (local == remote)\n");
 285                 } else if (!hashcmp(p->local, uninitialized) ||
 286                            !hashcmp(p->local, p->base)) {
 287                         /* no local change; adopt remote change */
 288                         trace_printf("\t\t\tno local change, adopted remote\n");
 289                         if (add_note(t, p->obj, p->remote,
 290                                      combine_notes_overwrite))
 291                                 die("BUG: combine_notes_overwrite failed");
 292                 } else {
 293                         /* need file-level merge between local and remote */
 294                         trace_printf("\t\t\tneed content-level merge\n");
 295                         conflicts += 1; /* TODO */
 296                 }
 297         }
 298
 299         return conflicts;
 300 }
 301
 302 static int merge_from_diffs(struct notes_merge_options *o,
 303                             const unsigned char *base,
 304                             const unsigned char *local,
 305                             const unsigned char *remote, struct notes_tree *t)
 306 {
 307         struct notes_merge_pair *changes;
 308         int num_changes, conflicts;
 309
 310         trace_printf("\tmerge_from_diffs(base = %.7s, local = %.7s, "
 311                "remote = %.7s)\n", sha1_to_hex(base), sha1_to_hex(local),
 312                sha1_to_hex(remote));
 313
 314         changes = diff_tree_remote(o, base, remote, &num_changes);
 315         diff_tree_local(o, changes, num_changes, base, local);
 316
 317         conflicts = merge_changes(o, changes, &num_changes, t);
 318         free(changes);
 319
 320         OUTPUT(o, 4, "Merge result: %i unmerged notes and a %s notes tree",
 321                conflicts, t->dirty ? "dirty" : "clean");
 322
 323         return conflicts ? -1 : 1;
 324 }
 325
 326 void create_notes_commit(struct notes_tree *t, struct commit_list *parents,
 327                          const char *msg, unsigned char *result_sha1)
 328 {
 329         unsigned char tree_sha1[20];
 330
 331         assert(t->initialized);
 332
 333         if (write_notes_tree(t, tree_sha1))
 334                 die("Failed to write notes tree to database");
 335
 336         if (!parents) {
 337                 /* Deduce parent commit from t->ref */
 338                 unsigned char parent_sha1[20];
 339                 if (!read_ref(t->ref, parent_sha1)) {
 340                         struct commit *parent = lookup_commit(parent_sha1);
 341                         if (!parent || parse_commit(parent))
 342                                 die("Failed to find/parse commit %s", t->ref);
 343                         commit_list_insert(parent, &parents);
 344                 }
 345                 /* else: t->ref points to nothing, assume root/orphan commit */
 346         }
 347
 348         if (commit_tree(msg, tree_sha1, parents, result_sha1, NULL))
 349                 die("Failed to commit notes tree to database");
 350 }
 351
 352 int notes_merge(struct notes_merge_options *o,
 353                 struct notes_tree *local_tree,
 354                 unsigned char *result_sha1)
 355 {
 356         unsigned char local_sha1[20], remote_sha1[20];
 357         struct commit *local, *remote;
 358         struct commit_list *bases = NULL;
 359         const unsigned char *base_sha1, *base_tree_sha1;
 360         int result = 0;
 361
 362         assert(o->local_ref && o->remote_ref);
 363         assert(!strcmp(o->local_ref, local_tree->ref));
 364         hashclr(result_sha1);
 365
 366         trace_printf("notes_merge(o->local_ref = %s, o->remote_ref = %s)\n",
 367                o->local_ref, o->remote_ref);
 368
 369         /* Dereference o->local_ref into local_sha1 */
 370         if (!resolve_ref(o->local_ref, local_sha1, 0, NULL))
 371                 die("Failed to resolve local notes ref '%s'", o->local_ref);
 372         else if (!check_ref_format(o->local_ref) && is_null_sha1(local_sha1))
 373                 local = NULL; /* local_sha1 == null_sha1 indicates unborn ref */
 374         else if (!(local = lookup_commit_reference(local_sha1)))
 375                 die("Could not parse local commit %s (%s)",
 376                     sha1_to_hex(local_sha1), o->local_ref);
 377         trace_printf("\tlocal commit: %.7s\n", sha1_to_hex(local_sha1));
 378
 379         /* Dereference o->remote_ref into remote_sha1 */
 380         if (get_sha1(o->remote_ref, remote_sha1)) {
 381                 /*
 382                  * Failed to get remote_sha1. If o->remote_ref looks like an
 383                  * unborn ref, perform the merge using an empty notes tree.
 384                  */
 385                 if (!check_ref_format(o->remote_ref)) {
 386                         hashclr(remote_sha1);
 387                         remote = NULL;
 388                 } else {
 389                         die("Failed to resolve remote notes ref '%s'",
 390                             o->remote_ref);
 391                 }
 392         } else if (!(remote = lookup_commit_reference(remote_sha1))) {
 393                 die("Could not parse remote commit %s (%s)",
 394                     sha1_to_hex(remote_sha1), o->remote_ref);
 395         }
 396         trace_printf("\tremote commit: %.7s\n", sha1_to_hex(remote_sha1));
 397
 398         if (!local && !remote)
 399                 die("Cannot merge empty notes ref (%s) into empty notes ref "
 400                     "(%s)", o->remote_ref, o->local_ref);
 401         if (!local) {
 402                 /* result == remote commit */
 403                 hashcpy(result_sha1, remote_sha1);
 404                 goto found_result;
 405         }
 406         if (!remote) {
 407                 /* result == local commit */
 408                 hashcpy(result_sha1, local_sha1);
 409                 goto found_result;
 410         }
 411         assert(local && remote);
 412
 413         /* Find merge bases */
 414         bases = get_merge_bases(local, remote, 1);
 415         if (!bases) {
 416                 base_sha1 = null_sha1;
 417                 base_tree_sha1 = (unsigned char *)EMPTY_TREE_SHA1_BIN;
 418                 OUTPUT(o, 4, "No merge base found; doing history-less merge");
 419         } else if (!bases->next) {
 420                 base_sha1 = bases->item->object.sha1;
 421                 base_tree_sha1 = bases->item->tree->object.sha1;
 422                 OUTPUT(o, 4, "One merge base found (%.7s)",
 423                        sha1_to_hex(base_sha1));
 424         } else {
 425                 /* TODO: How to handle multiple merge-bases? */
 426                 base_sha1 = bases->item->object.sha1;
 427                 base_tree_sha1 = bases->item->tree->object.sha1;
 428                 OUTPUT(o, 3, "Multiple merge bases found. Using the first "
 429                        "(%.7s)", sha1_to_hex(base_sha1));
 430         }
 431
 432         OUTPUT(o, 4, "Merging remote commit %.7s into local commit %.7s with "
 433                "merge-base %.7s", sha1_to_hex(remote->object.sha1),
 434                sha1_to_hex(local->object.sha1), sha1_to_hex(base_sha1));
 435
 436         if (!hashcmp(remote->object.sha1, base_sha1)) {
 437                 /* Already merged; result == local commit */
 438                 OUTPUT(o, 2, "Already up-to-date!");
 439                 hashcpy(result_sha1, local->object.sha1);
 440                 goto found_result;
 441         }
 442         if (!hashcmp(local->object.sha1, base_sha1)) {
 443                 /* Fast-forward; result == remote commit */
 444                 OUTPUT(o, 2, "Fast-forward");
 445                 hashcpy(result_sha1, remote->object.sha1);
 446                 goto found_result;
 447         }
 448
 449         result = merge_from_diffs(o, base_tree_sha1, local->tree->object.sha1,
 450                                   remote->tree->object.sha1, local_tree);
 451
 452         if (result > 0) { /* successful non-trivial merge */
 453                 /* Commit result */
 454                 struct commit_list *parents = NULL;
 455                 commit_list_insert(remote, &parents); /* LIFO order */
 456                 commit_list_insert(local, &parents);
 457                 create_notes_commit(local_tree, parents, o->commit_msg,
 458                                     result_sha1);
 459         }
 460
 461 found_result:
 462         free_commit_list(bases);
 463         trace_printf("notes_merge(): result = %i, result_sha1 = %.7s\n",
 464                result, sha1_to_hex(result_sha1));
 465         return result;
 466 }