read-tree.c

   1 /*
   2  * GIT - The information manager from hell
   3  *
   4  * Copyright (C) Linus Torvalds, 2005
   5  */
   6 #include "cache.h"
   7
   8 #include "object.h"
   9 #include "tree.h"
  10
  11 static int merge = 0;
  12 static int update = 0;
  13
  14 static int head_idx = -1;
  15 static int merge_size = 0;
  16
  17 static struct object_list *trees = NULL;
  18
  19 static struct cache_entry df_conflict_entry = {
  20 };
  21
  22 static struct tree_entry_list df_conflict_list = {
  23         .name = NULL,
  24         .next = &df_conflict_list
  25 };
  26
  27 typedef int (*merge_fn_t)(struct cache_entry **src);
  28
  29 static int entcmp(char *name1, int dir1, char *name2, int dir2)
  30 {
  31         int len1 = strlen(name1);
  32         int len2 = strlen(name2);
  33         int len = len1 < len2 ? len1 : len2;
  34         int ret = memcmp(name1, name2, len);
  35         unsigned char c1, c2;
  36         if (ret)
  37                 return ret;
  38         c1 = name1[len];
  39         c2 = name2[len];
  40         if (!c1 && dir1)
  41                 c1 = '/';
  42         if (!c2 && dir2)
  43                 c2 = '/';
  44         ret = (c1 < c2) ? -1 : (c1 > c2) ? 1 : 0;
  45         if (c1 && c2 && !ret)
  46                 ret = len1 - len2;
  47         return ret;
  48 }
  49
  50 static int unpack_trees_rec(struct tree_entry_list **posns, int len,
  51                             const char *base, merge_fn_t fn, int *indpos)
  52 {
  53         int baselen = strlen(base);
  54         int src_size = len + 1;
  55         do {
  56                 int i;
  57                 char *first;
  58                 int firstdir = 0;
  59                 int pathlen;
  60                 unsigned ce_size;
  61                 struct tree_entry_list **subposns;
  62                 struct cache_entry **src;
  63                 int any_files = 0;
  64                 int any_dirs = 0;
  65                 char *cache_name;
  66                 int ce_stage;
  67
  68                 /* Find the first name in the input. */
  69
  70                 first = NULL;
  71                 cache_name = NULL;
  72
  73                 /* Check the cache */
  74                 if (merge && *indpos < active_nr) {
  75                         /* This is a bit tricky: */
  76                         /* If the index has a subdirectory (with
  77                          * contents) as the first name, it'll get a
  78                          * filename like "foo/bar". But that's after
  79                          * "foo", so the entry in trees will get
  80                          * handled first, at which point we'll go into
  81                          * "foo", and deal with "bar" from the index,
  82                          * because the base will be "foo/". The only
  83                          * way we can actually have "foo/bar" first of
  84                          * all the things is if the trees don't
  85                          * contain "foo" at all, in which case we'll
  86                          * handle "foo/bar" without going into the
  87                          * directory, but that's fine (and will return
  88                          * an error anyway, with the added unknown
  89                          * file case.
  90                          */
  91
  92                         cache_name = active_cache[*indpos]->name;
  93                         if (strlen(cache_name) > baselen &&
  94                             !memcmp(cache_name, base, baselen)) {
  95                                 cache_name += baselen;
  96                                 first = cache_name;
  97                         } else {
  98                                 cache_name = NULL;
  99                         }
 100                 }
 101
 102                 if (first)
 103                         printf("index %s\n", first);
 104
 105                 for (i = 0; i < len; i++) {
 106                         if (!posns[i] || posns[i] == &df_conflict_list)
 107                                 continue;
 108                         printf("%d %s\n", i + 1, posns[i]->name);
 109                         if (!first || entcmp(first, firstdir,
 110                                              posns[i]->name,
 111                                              posns[i]->directory) > 0) {
 112                                 first = posns[i]->name;
 113                                 firstdir = posns[i]->directory;
 114                         }
 115                 }
 116                 /* No name means we're done */
 117                 if (!first)
 118                         return 0;
 119
 120                 pathlen = strlen(first);
 121                 ce_size = cache_entry_size(baselen + pathlen);
 122
 123                 src = xmalloc(sizeof(struct cache_entry *) * src_size);
 124                 memset(src, 0, sizeof(struct cache_entry *) * src_size);
 125
 126                 subposns = xmalloc(sizeof(struct tree_list_entry *) * len);
 127                 memset(subposns, 0, sizeof(struct tree_list_entry *) * len);
 128
 129                 if (cache_name && !strcmp(cache_name, first)) {
 130                         any_files = 1;
 131                         src[0] = active_cache[*indpos];
 132                         remove_cache_entry_at(*indpos);
 133                 }
 134
 135                 for (i = 0; i < len; i++) {
 136                         struct cache_entry *ce;
 137
 138                         if (!posns[i] ||
 139                             (posns[i] != &df_conflict_list &&
 140                              strcmp(first, posns[i]->name))) {
 141                                 continue;
 142                         }
 143
 144                         if (posns[i] == &df_conflict_list) {
 145                                 src[i + merge] = &df_conflict_entry;
 146                                 continue;
 147                         }
 148
 149                         if (posns[i]->directory) {
 150                                 any_dirs = 1;
 151                                 parse_tree(posns[i]->item.tree);
 152                                 subposns[i] = posns[i]->item.tree->entries;
 153                                 posns[i] = posns[i]->next;
 154                                 src[i + merge] = &df_conflict_entry;
 155                                 continue;
 156                         }
 157
 158                         if (!merge)
 159                                 ce_stage = 0;
 160                         else if (i + 1 < head_idx)
 161                                 ce_stage = 1;
 162                         else if (i + 1 > head_idx)
 163                                 ce_stage = 3;
 164                         else
 165                                 ce_stage = 2;
 166
 167                         ce = xmalloc(ce_size);
 168                         memset(ce, 0, ce_size);
 169                         ce->ce_mode = create_ce_mode(posns[i]->mode);
 170                         ce->ce_flags = create_ce_flags(baselen + pathlen,
 171                                                        ce_stage);
 172                         memcpy(ce->name, base, baselen);
 173                         memcpy(ce->name + baselen, first, pathlen + 1);
 174
 175                         any_files = 1;
 176
 177                         memcpy(ce->sha1, posns[i]->item.any->sha1, 20);
 178                         src[i + merge] = ce;
 179                         subposns[i] = &df_conflict_list;
 180                         posns[i] = posns[i]->next;
 181                 }
 182                 if (any_files) {
 183                         if (merge) {
 184                                 int ret;
 185
 186                                 printf("%s:\n", first);
 187                                 for (i = 0; i < src_size; i++) {
 188                                         printf(" %d ", i);
 189                                         if (src[i])
 190                                                 printf("%s\n", sha1_to_hex(src[i]->sha1));
 191                                         else
 192                                                 printf("\n");
 193                                 }
 194
 195                                 ret = fn(src);
 196
 197                                 printf("Added %d entries\n", ret);
 198
 199                                 *indpos += ret;
 200                         } else {
 201                                 for (i = 0; i < src_size; i++) {
 202                                         if (src[i]) {
 203                                                 add_cache_entry(src[i], ADD_CACHE_OK_TO_ADD|ADD_CACHE_SKIP_DFCHECK);
 204                                         }
 205                                 }
 206                         }
 207                 }
 208                 if (any_dirs) {
 209                         char *newbase = xmalloc(baselen + 2 + pathlen);
 210                         memcpy(newbase, base, baselen);
 211                         memcpy(newbase + baselen, first, pathlen);
 212                         newbase[baselen + pathlen] = '/';
 213                         newbase[baselen + pathlen + 1] = '\0';
 214                         if (unpack_trees_rec(subposns, len, newbase, fn,
 215                                              indpos))
 216                                 return -1;
 217                 }
 218                 free(subposns);
 219                 free(src);
 220         } while (1);
 221 }
 222
 223 static void reject_merge(struct cache_entry *ce)
 224 {
 225         die("Entry '%s' would be overwritten by merge. Cannot merge.",
 226             ce->name);
 227 }
 228
 229 static void check_updates(struct cache_entry **src, int nr)
 230 {
 231         static struct checkout state = {
 232                 .base_dir = "",
 233                 .force = 1,
 234                 .quiet = 1,
 235                 .refresh_cache = 1,
 236         };
 237         unsigned short mask = htons(CE_UPDATE);
 238         while (nr--) {
 239                 struct cache_entry *ce = *src++;
 240                 if (!ce->ce_mode) {
 241                         if (update)
 242                                 unlink(ce->name);
 243                         continue;
 244                 }
 245                 if (ce->ce_flags & mask) {
 246                         ce->ce_flags &= ~mask;
 247                         if (update)
 248                                 checkout_entry(ce, &state);
 249                 }
 250         }
 251 }
 252
 253 static int unpack_trees(merge_fn_t fn)
 254 {
 255         int indpos = 0;
 256         unsigned len = object_list_length(trees);
 257         struct tree_entry_list **posns =
 258                 xmalloc(len * sizeof(struct tree_entry_list *));
 259         int i;
 260         struct object_list *posn = trees;
 261         merge_size = len;
 262         for (i = 0; i < len; i++) {
 263                 posns[i] = ((struct tree *) posn->item)->entries;
 264                 posn = posn->next;
 265         }
 266         if (unpack_trees_rec(posns, len, "", fn, &indpos))
 267                 return -1;
 268
 269         check_updates(active_cache, active_nr);
 270         return 0;
 271 }
 272
 273 static int list_tree(unsigned char *sha1)
 274 {
 275         struct tree *tree = parse_tree_indirect(sha1);
 276         if (!tree)
 277                 return -1;
 278         object_list_append(&tree->object, &trees);
 279         return 0;
 280 }
 281
 282 static int same(struct cache_entry *a, struct cache_entry *b)
 283 {
 284         if (!!a != !!b)
 285                 return 0;
 286         if (!a && !b)
 287                 return 1;
 288         return a->ce_mode == b->ce_mode &&
 289                 !memcmp(a->sha1, b->sha1, 20);
 290 }
 291
 292
 293 /*
 294  * When a CE gets turned into an unmerged entry, we
 295  * want it to be up-to-date
 296  */
 297 static void verify_uptodate(struct cache_entry *ce)
 298 {
 299         struct stat st;
 300
 301         if (!lstat(ce->name, &st)) {
 302                 unsigned changed = ce_match_stat(ce, &st);
 303                 if (!changed)
 304                         return;
 305                 errno = 0;
 306         }
 307         if (errno == ENOENT)
 308                 return;
 309         die("Entry '%s' not uptodate. Cannot merge.", ce->name);
 310 }
 311
 312 static int merged_entry(struct cache_entry *merge, struct cache_entry *old)
 313 {
 314         merge->ce_flags |= htons(CE_UPDATE);
 315         if (old) {
 316                 /*
 317                  * See if we can re-use the old CE directly?
 318                  * That way we get the uptodate stat info.
 319                  *
 320                  * This also removes the UPDATE flag on
 321                  * a match.
 322                  */
 323                 if (same(old, merge)) {
 324                         *merge = *old;
 325                 } else {
 326                         verify_uptodate(old);
 327                 }
 328         }
 329         merge->ce_flags &= ~htons(CE_STAGEMASK);
 330         add_cache_entry(merge, ADD_CACHE_OK_TO_ADD);
 331         return 1;
 332 }
 333
 334 static int deleted_entry(struct cache_entry *ce, struct cache_entry *old)
 335 {
 336         if (old)
 337                 verify_uptodate(old);
 338         ce->ce_mode = 0;
 339         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
 340         return 1;
 341 }
 342
 343 static int keep_entry(struct cache_entry *ce)
 344 {
 345         add_cache_entry(ce, ADD_CACHE_OK_TO_ADD);
 346         return 1;
 347 }
 348
 349 static int threeway_merge(struct cache_entry **stages)
 350 {
 351         struct cache_entry *index;
 352         struct cache_entry *head;
 353         struct cache_entry *remote = stages[head_idx + 1];
 354         int count;
 355         int head_match = 0;
 356         int remote_match = 0;
 357
 358         int df_conflict_head = 0;
 359         int df_conflict_remote = 0;
 360
 361         int any_anc_missing = 0;
 362         int i;
 363
 364         for (i = 1; i < head_idx; i++) {
 365                 if (!stages[i])
 366                         any_anc_missing = 1;
 367         }
 368
 369         index = stages[0];
 370         head = stages[head_idx];
 371
 372         if (head == &df_conflict_entry) {
 373                 df_conflict_head = 1;
 374                 head = NULL;
 375         }
 376
 377         if (remote == &df_conflict_entry) {
 378                 df_conflict_remote = 1;
 379                 remote = NULL;
 380         }
 381
 382         /* First, if there's a #16 situation, note that to prevent #13
 383          * and #14.
 384          */
 385         if (!same(remote, head)) {
 386                 for (i = 1; i < head_idx; i++) {
 387                         if (same(stages[i], head)) {
 388                                 head_match = 1;
 389                         }
 390                         if (same(stages[i], remote)) {
 391                                 remote_match = 1;
 392                         }
 393                 }
 394         }
 395
 396         /* We start with cases where the index is allowed to match
 397          * something other than the head: #14(ALT) and #2ALT, where it
 398          * is permitted to match the result instead.
 399          */
 400         /* #14, #14ALT, #2ALT */
 401         if (remote && !df_conflict_head && head_match && !remote_match) {
 402                 if (index && !same(index, remote) && !same(index, head))
 403                         reject_merge(index);
 404                 return merged_entry(remote, index);
 405         }
 406         /*
 407          * If we have an entry in the index cache, then we want to
 408          * make sure that it matches head.
 409          */
 410         if (index && !same(index, head)) {
 411                 reject_merge(index);
 412         }
 413
 414         if (head) {
 415                 /* #5ALT, #15 */
 416                 if (same(head, remote))
 417                         return merged_entry(head, index);
 418                 /* #13, #3ALT */
 419                 if (!df_conflict_remote && remote_match && !head_match)
 420                         return merged_entry(head, index);
 421         }
 422
 423         /* #1 */
 424         if (!head && !remote && any_anc_missing)
 425                 return 0;
 426
 427         /* Below are "no merge" cases, which require that the index be
 428          * up-to-date to avoid the files getting overwritten with
 429          * conflict resolution files.
 430          */
 431         if (index) {
 432                 verify_uptodate(index);
 433         }
 434
 435         /* #2, #3, #4, #6, #7, #9, #11. */
 436         count = 0;
 437         if (!head_match || !remote_match) {
 438                 for (i = 1; i < head_idx; i++) {
 439                         if (stages[i]) {
 440                                 keep_entry(stages[i]);
 441                                 count++;
 442                                 break;
 443                         }
 444                 }
 445         }
 446         if (head) { count += keep_entry(head); }
 447         if (remote) { count += keep_entry(remote); }
 448         return count;
 449 }
 450
 451 /*
 452  * Two-way merge.
 453  *
 454  * The rule is to "carry forward" what is in the index without losing
 455  * information across a "fast forward", favoring a successful merge
 456  * over a merge failure when it makes sense.  For details of the
 457  * "carry forward" rule, please see <Documentation/git-read-tree.txt>.
 458  *
 459  */
 460 static int twoway_merge(struct cache_entry **src)
 461 {
 462         struct cache_entry *current = src[0];
 463         struct cache_entry *oldtree = src[1], *newtree = src[2];
 464
 465         if (merge_size != 2)
 466                 return error("Cannot do a twoway merge of %d trees\n",
 467                              merge_size);
 468
 469         if (current) {
 470                 if ((!oldtree && !newtree) || /* 4 and 5 */
 471                     (!oldtree && newtree &&
 472                      same(current, newtree)) || /* 6 and 7 */
 473                     (oldtree && newtree &&
 474                      same(oldtree, newtree)) || /* 14 and 15 */
 475                     (oldtree && newtree &&
 476                      !same(oldtree, newtree) && /* 18 and 19*/
 477                      same(current, newtree))) {
 478                         return keep_entry(current);
 479                 }
 480                 else if (oldtree && !newtree && same(current, oldtree)) {
 481                         /* 10 or 11 */
 482                         return deleted_entry(oldtree, current);
 483                 }
 484                 else if (oldtree && newtree &&
 485                          same(current, oldtree) && !same(current, newtree)) {
 486                         /* 20 or 21 */
 487                         return merged_entry(newtree, current);
 488                 }
 489                 else {
 490                         /* all other failures */
 491                         if (oldtree)
 492                                 reject_merge(oldtree);
 493                         if (current)
 494                                 reject_merge(current);
 495                         if (newtree)
 496                                 reject_merge(newtree);
 497                         return -1;
 498                 }
 499         }
 500         else if (newtree)
 501                 return merged_entry(newtree, current);
 502         else
 503                 return deleted_entry(oldtree, current);
 504 }
 505
 506 /*
 507  * One-way merge.
 508  *
 509  * The rule is:
 510  * - take the stat information from stage0, take the data from stage1
 511  */
 512 static int oneway_merge(struct cache_entry **src)
 513 {
 514         struct cache_entry *old = src[0];
 515         struct cache_entry *a = src[1];
 516
 517         if (merge_size != 1)
 518                 return error("Cannot do a oneway merge of %d trees\n",
 519                              merge_size);
 520
 521         if (!a)
 522                 return 0;
 523         if (old && same(old, a)) {
 524                 return keep_entry(old);
 525         }
 526         return merged_entry(a, NULL);
 527 }
 528
 529 static int read_cache_unmerged(void)
 530 {
 531         int i, deleted;
 532         struct cache_entry **dst;
 533
 534         read_cache();
 535         dst = active_cache;
 536         deleted = 0;
 537         for (i = 0; i < active_nr; i++) {
 538                 struct cache_entry *ce = active_cache[i];
 539                 if (ce_stage(ce)) {
 540                         deleted++;
 541                         continue;
 542                 }
 543                 if (deleted)
 544                         *dst = ce;
 545                 dst++;
 546         }
 547         active_nr -= deleted;
 548         return deleted;
 549 }
 550
 551 static const char read_tree_usage[] = "git-read-tree (<sha> | -m [-u] <sha1> [<sha2> [<sha3>]])";
 552
 553 static struct cache_file cache_file;
 554
 555 int main(int argc, char **argv)
 556 {
 557         int i, newfd, reset, stage = 0;
 558         unsigned char sha1[20];
 559         merge_fn_t fn = NULL;
 560
 561         newfd = hold_index_file_for_update(&cache_file, get_index_file());
 562         if (newfd < 0)
 563                 die("unable to create new cachefile");
 564
 565         merge = 0;
 566         reset = 0;
 567         for (i = 1; i < argc; i++) {
 568                 const char *arg = argv[i];
 569
 570                 /* "-u" means "update", meaning that a merge will update the working directory */
 571                 if (!strcmp(arg, "-u")) {
 572                         update = 1;
 573                         continue;
 574                 }
 575
 576                 /* This differs from "-m" in that we'll silently ignore unmerged entries */
 577                 if (!strcmp(arg, "--reset")) {
 578                         if (stage || merge)
 579                                 usage(read_tree_usage);
 580                         reset = 1;
 581                         merge = 1;
 582                         stage = 1;
 583                         read_cache_unmerged();
 584                         continue;
 585                 }
 586
 587                 if (!strcmp(arg, "--head")) {
 588                         head_idx = stage - 1;
 589                         fn = threeway_merge;
 590                 }
 591
 592                 /* "-m" stands for "merge", meaning we start in stage 1 */
 593                 if (!strcmp(arg, "-m")) {
 594                         if (stage || merge)
 595                                 usage(read_tree_usage);
 596                         if (read_cache_unmerged())
 597                                 die("you need to resolve your current index first");
 598                         stage = 1;
 599                         merge = 1;
 600                         continue;
 601                 }
 602
 603                 if (get_sha1(arg, sha1) < 0)
 604                         usage(read_tree_usage);
 605                 if (list_tree(sha1) < 0)
 606                         die("failed to unpack tree object %s", arg);
 607                 stage++;
 608         }
 609         if (update && !merge)
 610                 usage(read_tree_usage);
 611         if (merge && !fn) {
 612                 if (stage < 2)
 613                         die("just how do you expect me to merge %d trees?", stage-1);
 614                 switch (stage - 1) {
 615                 case 1:
 616                         fn = oneway_merge;
 617                         break;
 618                 case 2:
 619                         fn = twoway_merge;
 620                         break;
 621                 case 3:
 622                         fn = threeway_merge;
 623                         break;
 624                 default:
 625                         fn = threeway_merge;
 626                         break;
 627                 }
 628         }
 629
 630         if (head_idx < 0) {
 631                 if (stage - 1 >= 3)
 632                         head_idx = stage - 2;
 633                 else
 634                         head_idx = 1;
 635         }
 636
 637         unpack_trees(fn);
 638         if (write_cache(newfd, active_cache, active_nr) ||
 639             commit_index_file(&cache_file))
 640                 die("unable to write new index file");
 641         return 0;
 642 }