merge-recursive.c

   1 /*
   2  * Recursive Merge algorithm stolen from git-merge-recursive.py by
   3  * Fredrik Kuivinen.
   4  * The thieves were Alex Riesen and Johannes Schindelin, in June/July 2006
   5  */
   6 #include "advice.h"
   7 #include "cache.h"
   8 #include "cache-tree.h"
   9 #include "commit.h"
  10 #include "blob.h"
  11 #include "builtin.h"
  12 #include "tree-walk.h"
  13 #include "diff.h"
  14 #include "diffcore.h"
  15 #include "tag.h"
  16 #include "unpack-trees.h"
  17 #include "string-list.h"
  18 #include "xdiff-interface.h"
  19 #include "ll-merge.h"
  20 #include "attr.h"
  21 #include "merge-recursive.h"
  22 #include "dir.h"
  23 #include "submodule.h"
  24
  25 static struct tree *shift_tree_object(struct tree *one, struct tree *two,
  26                                       const char *subtree_shift)
  27 {
  28         unsigned char shifted[20];
  29
  30         if (!*subtree_shift) {
  31                 shift_tree(one->object.sha1, two->object.sha1, shifted, 0);
  32         } else {
  33                 shift_tree_by(one->object.sha1, two->object.sha1, shifted,
  34                               subtree_shift);
  35         }
  36         if (!hashcmp(two->object.sha1, shifted))
  37                 return two;
  38         return lookup_tree(shifted);
  39 }
  40
  41 /*
  42  * A virtual commit has (const char *)commit->util set to the name.
  43  */
  44
  45 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  46 {
  47         struct commit *commit = xcalloc(1, sizeof(struct commit));
  48         commit->tree = tree;
  49         commit->util = (void*)comment;
  50         /* avoid warnings */
  51         commit->object.parsed = 1;
  52         return commit;
  53 }
  54
  55 /*
  56  * Since we use get_tree_entry(), which does not put the read object into
  57  * the object pool, we cannot rely on a == b.
  58  */
  59 static int sha_eq(const unsigned char *a, const unsigned char *b)
  60 {
  61         if (!a && !b)
  62                 return 2;
  63         return a && b && hashcmp(a, b) == 0;
  64 }
  65
  66 enum rename_type {
  67         RENAME_NORMAL = 0,
  68         RENAME_DELETE,
  69         RENAME_ONE_FILE_TO_ONE,
  70         RENAME_ONE_FILE_TO_TWO
  71 };
  72
  73 struct rename_conflict_info {
  74         enum rename_type rename_type;
  75         struct diff_filepair *pair1;
  76         struct diff_filepair *pair2;
  77         const char *branch1;
  78         const char *branch2;
  79         struct stage_data *dst_entry1;
  80         struct stage_data *dst_entry2;
  81 };
  82
  83 /*
  84  * Since we want to write the index eventually, we cannot reuse the index
  85  * for these (temporary) data.
  86  */
  87 struct stage_data {
  88         struct {
  89                 unsigned mode;
  90                 unsigned char sha[20];
  91         } stages[4];
  92         struct rename_conflict_info *rename_conflict_info;
  93         unsigned processed:1;
  94 };
  95
  96 static inline void setup_rename_conflict_info(enum rename_type rename_type,
  97                                               struct diff_filepair *pair1,
  98                                               struct diff_filepair *pair2,
  99                                               const char *branch1,
 100                                               const char *branch2,
 101                                               struct stage_data *dst_entry1,
 102                                               struct stage_data *dst_entry2)
 103 {
 104         struct rename_conflict_info *ci = xcalloc(1, sizeof(struct rename_conflict_info));
 105         ci->rename_type = rename_type;
 106         ci->pair1 = pair1;
 107         ci->branch1 = branch1;
 108         ci->branch2 = branch2;
 109
 110         ci->dst_entry1 = dst_entry1;
 111         dst_entry1->rename_conflict_info = ci;
 112         dst_entry1->processed = 0;
 113
 114         assert(!pair2 == !dst_entry2);
 115         if (dst_entry2) {
 116                 ci->dst_entry2 = dst_entry2;
 117                 ci->pair2 = pair2;
 118                 dst_entry2->rename_conflict_info = ci;
 119         }
 120 }
 121
 122 static int show(struct merge_options *o, int v)
 123 {
 124         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
 125 }
 126
 127 static void flush_output(struct merge_options *o)
 128 {
 129         if (o->obuf.len) {
 130                 fputs(o->obuf.buf, stdout);
 131                 strbuf_reset(&o->obuf);
 132         }
 133 }
 134
 135 __attribute__((format (printf, 3, 4)))
 136 static void output(struct merge_options *o, int v, const char *fmt, ...)
 137 {
 138         va_list ap;
 139
 140         if (!show(o, v))
 141                 return;
 142
 143         strbuf_grow(&o->obuf, o->call_depth * 2 + 2);
 144         memset(o->obuf.buf + o->obuf.len, ' ', o->call_depth * 2);
 145         strbuf_setlen(&o->obuf, o->obuf.len + o->call_depth * 2);
 146
 147         va_start(ap, fmt);
 148         strbuf_vaddf(&o->obuf, fmt, ap);
 149         va_end(ap);
 150
 151         strbuf_add(&o->obuf, "\n", 1);
 152         if (!o->buffer_output)
 153                 flush_output(o);
 154 }
 155
 156 static void output_commit_title(struct merge_options *o, struct commit *commit)
 157 {
 158         int i;
 159         flush_output(o);
 160         for (i = o->call_depth; i--;)
 161                 fputs("  ", stdout);
 162         if (commit->util)
 163                 printf("virtual %s\n", (char *)commit->util);
 164         else {
 165                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 166                 if (parse_commit(commit) != 0)
 167                         printf("(bad commit)\n");
 168                 else {
 169                         const char *title;
 170                         int len = find_commit_subject(commit->buffer, &title);
 171                         if (len)
 172                                 printf("%.*s\n", len, title);
 173                 }
 174         }
 175 }
 176
 177 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 178                 const char *path, int stage, int refresh, int options)
 179 {
 180         struct cache_entry *ce;
 181         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 182         if (!ce)
 183                 return error("addinfo_cache failed for path '%s'", path);
 184         return add_cache_entry(ce, options);
 185 }
 186
 187 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 188 {
 189         parse_tree(tree);
 190         init_tree_desc(desc, tree->buffer, tree->size);
 191 }
 192
 193 static int git_merge_trees(int index_only,
 194                            struct tree *common,
 195                            struct tree *head,
 196                            struct tree *merge)
 197 {
 198         int rc;
 199         struct tree_desc t[3];
 200         struct unpack_trees_options opts;
 201
 202         memset(&opts, 0, sizeof(opts));
 203         if (index_only)
 204                 opts.index_only = 1;
 205         else
 206                 opts.update = 1;
 207         opts.merge = 1;
 208         opts.head_idx = 2;
 209         opts.fn = threeway_merge;
 210         opts.src_index = &the_index;
 211         opts.dst_index = &the_index;
 212         setup_unpack_trees_porcelain(&opts, "merge");
 213
 214         init_tree_desc_from_tree(t+0, common);
 215         init_tree_desc_from_tree(t+1, head);
 216         init_tree_desc_from_tree(t+2, merge);
 217
 218         rc = unpack_trees(3, t, &opts);
 219         cache_tree_free(&active_cache_tree);
 220         return rc;
 221 }
 222
 223 struct tree *write_tree_from_memory(struct merge_options *o)
 224 {
 225         struct tree *result = NULL;
 226
 227         if (unmerged_cache()) {
 228                 int i;
 229                 fprintf(stderr, "BUG: There are unmerged index entries:\n");
 230                 for (i = 0; i < active_nr; i++) {
 231                         struct cache_entry *ce = active_cache[i];
 232                         if (ce_stage(ce))
 233                                 fprintf(stderr, "BUG: %d %.*s\n", ce_stage(ce),
 234                                         (int)ce_namelen(ce), ce->name);
 235                 }
 236                 die("Bug in merge-recursive.c");
 237         }
 238
 239         if (!active_cache_tree)
 240                 active_cache_tree = cache_tree();
 241
 242         if (!cache_tree_fully_valid(active_cache_tree) &&
 243             cache_tree_update(active_cache_tree,
 244                               active_cache, active_nr, 0, 0) < 0)
 245                 die("error building trees");
 246
 247         result = lookup_tree(active_cache_tree->sha1);
 248
 249         return result;
 250 }
 251
 252 static int save_files_dirs(const unsigned char *sha1,
 253                 const char *base, int baselen, const char *path,
 254                 unsigned int mode, int stage, void *context)
 255 {
 256         int len = strlen(path);
 257         char *newpath = xmalloc(baselen + len + 1);
 258         struct merge_options *o = context;
 259
 260         memcpy(newpath, base, baselen);
 261         memcpy(newpath + baselen, path, len);
 262         newpath[baselen + len] = '\0';
 263
 264         if (S_ISDIR(mode))
 265                 string_list_insert(&o->current_directory_set, newpath);
 266         else
 267                 string_list_insert(&o->current_file_set, newpath);
 268         free(newpath);
 269
 270         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
 271 }
 272
 273 static int get_files_dirs(struct merge_options *o, struct tree *tree)
 274 {
 275         int n;
 276         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs, o))
 277                 return 0;
 278         n = o->current_file_set.nr + o->current_directory_set.nr;
 279         return n;
 280 }
 281
 282 /*
 283  * Returns an index_entry instance which doesn't have to correspond to
 284  * a real cache entry in Git's index.
 285  */
 286 static struct stage_data *insert_stage_data(const char *path,
 287                 struct tree *o, struct tree *a, struct tree *b,
 288                 struct string_list *entries)
 289 {
 290         struct string_list_item *item;
 291         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 292         get_tree_entry(o->object.sha1, path,
 293                         e->stages[1].sha, &e->stages[1].mode);
 294         get_tree_entry(a->object.sha1, path,
 295                         e->stages[2].sha, &e->stages[2].mode);
 296         get_tree_entry(b->object.sha1, path,
 297                         e->stages[3].sha, &e->stages[3].mode);
 298         item = string_list_insert(entries, path);
 299         item->util = e;
 300         return e;
 301 }
 302
 303 /*
 304  * Create a dictionary mapping file names to stage_data objects. The
 305  * dictionary contains one entry for every path with a non-zero stage entry.
 306  */
 307 static struct string_list *get_unmerged(void)
 308 {
 309         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
 310         int i;
 311
 312         unmerged->strdup_strings = 1;
 313
 314         for (i = 0; i < active_nr; i++) {
 315                 struct string_list_item *item;
 316                 struct stage_data *e;
 317                 struct cache_entry *ce = active_cache[i];
 318                 if (!ce_stage(ce))
 319                         continue;
 320
 321                 item = string_list_lookup(unmerged, ce->name);
 322                 if (!item) {
 323                         item = string_list_insert(unmerged, ce->name);
 324                         item->util = xcalloc(1, sizeof(struct stage_data));
 325                 }
 326                 e = item->util;
 327                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
 328                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 329         }
 330
 331         return unmerged;
 332 }
 333
 334 static int string_list_df_name_compare(const void *a, const void *b)
 335 {
 336         const struct string_list_item *one = a;
 337         const struct string_list_item *two = b;
 338         int onelen = strlen(one->string);
 339         int twolen = strlen(two->string);
 340         /*
 341          * Here we only care that entries for D/F conflicts are
 342          * adjacent, in particular with the file of the D/F conflict
 343          * appearing before files below the corresponding directory.
 344          * The order of the rest of the list is irrelevant for us.
 345          *
 346          * To achieve this, we sort with df_name_compare and provide
 347          * the mode S_IFDIR so that D/F conflicts will sort correctly.
 348          * We use the mode S_IFDIR for everything else for simplicity,
 349          * since in other cases any changes in their order due to
 350          * sorting cause no problems for us.
 351          */
 352         int cmp = df_name_compare(one->string, onelen, S_IFDIR,
 353                                   two->string, twolen, S_IFDIR);
 354         /*
 355          * Now that 'foo' and 'foo/bar' compare equal, we have to make sure
 356          * that 'foo' comes before 'foo/bar'.
 357          */
 358         if (cmp)
 359                 return cmp;
 360         return onelen - twolen;
 361 }
 362
 363 static void record_df_conflict_files(struct merge_options *o,
 364                                      struct string_list *entries)
 365 {
 366         /* If there is a D/F conflict and the file for such a conflict
 367          * currently exist in the working copy, we want to allow it to be
 368          * removed to make room for the corresponding directory if needed.
 369          * The files underneath the directories of such D/F conflicts will
 370          * be processed before the corresponding file involved in the D/F
 371          * conflict.  If the D/F directory ends up being removed by the
 372          * merge, then we won't have to touch the D/F file.  If the D/F
 373          * directory needs to be written to the working copy, then the D/F
 374          * file will simply be removed (in make_room_for_path()) to make
 375          * room for the necessary paths.  Note that if both the directory
 376          * and the file need to be present, then the D/F file will be
 377          * reinstated with a new unique name at the time it is processed.
 378          */
 379         const char *last_file = NULL;
 380         int last_len = 0;
 381         int i;
 382
 383         /*
 384          * If we're merging merge-bases, we don't want to bother with
 385          * any working directory changes.
 386          */
 387         if (o->call_depth)
 388                 return;
 389
 390         /* Ensure D/F conflicts are adjacent in the entries list. */
 391         qsort(entries->items, entries->nr, sizeof(*entries->items),
 392               string_list_df_name_compare);
 393
 394         string_list_clear(&o->df_conflict_file_set, 1);
 395         for (i = 0; i < entries->nr; i++) {
 396                 const char *path = entries->items[i].string;
 397                 int len = strlen(path);
 398                 struct stage_data *e = entries->items[i].util;
 399
 400                 /*
 401                  * Check if last_file & path correspond to a D/F conflict;
 402                  * i.e. whether path is last_file+'/'+<something>.
 403                  * If so, record that it's okay to remove last_file to make
 404                  * room for path and friends if needed.
 405                  */
 406                 if (last_file &&
 407                     len > last_len &&
 408                     memcmp(path, last_file, last_len) == 0 &&
 409                     path[last_len] == '/') {
 410                         string_list_insert(&o->df_conflict_file_set, last_file);
 411                 }
 412
 413                 /*
 414                  * Determine whether path could exist as a file in the
 415                  * working directory as a possible D/F conflict.  This
 416                  * will only occur when it exists in stage 2 as a
 417                  * file.
 418                  */
 419                 if (S_ISREG(e->stages[2].mode) || S_ISLNK(e->stages[2].mode)) {
 420                         last_file = path;
 421                         last_len = len;
 422                 } else {
 423                         last_file = NULL;
 424                 }
 425         }
 426 }
 427
 428 struct rename {
 429         struct diff_filepair *pair;
 430         struct stage_data *src_entry;
 431         struct stage_data *dst_entry;
 432         unsigned processed:1;
 433 };
 434
 435 /*
 436  * Get information of all renames which occurred between 'o_tree' and
 437  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 438  * 'b_tree') to be able to associate the correct cache entries with
 439  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 440  */
 441 static struct string_list *get_renames(struct merge_options *o,
 442                                        struct tree *tree,
 443                                        struct tree *o_tree,
 444                                        struct tree *a_tree,
 445                                        struct tree *b_tree,
 446                                        struct string_list *entries)
 447 {
 448         int i;
 449         struct string_list *renames;
 450         struct diff_options opts;
 451
 452         renames = xcalloc(1, sizeof(struct string_list));
 453         diff_setup(&opts);
 454         DIFF_OPT_SET(&opts, RECURSIVE);
 455         opts.detect_rename = DIFF_DETECT_RENAME;
 456         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 457                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 458                             1000;
 459         opts.rename_score = o->rename_score;
 460         opts.show_rename_progress = o->show_rename_progress;
 461         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 462         if (diff_setup_done(&opts) < 0)
 463                 die("diff setup failed");
 464         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 465         diffcore_std(&opts);
 466         if (opts.needed_rename_limit > o->needed_rename_limit)
 467                 o->needed_rename_limit = opts.needed_rename_limit;
 468         for (i = 0; i < diff_queued_diff.nr; ++i) {
 469                 struct string_list_item *item;
 470                 struct rename *re;
 471                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 472                 if (pair->status != 'R') {
 473                         diff_free_filepair(pair);
 474                         continue;
 475                 }
 476                 re = xmalloc(sizeof(*re));
 477                 re->processed = 0;
 478                 re->pair = pair;
 479                 item = string_list_lookup(entries, re->pair->one->path);
 480                 if (!item)
 481                         re->src_entry = insert_stage_data(re->pair->one->path,
 482                                         o_tree, a_tree, b_tree, entries);
 483                 else
 484                         re->src_entry = item->util;
 485
 486                 item = string_list_lookup(entries, re->pair->two->path);
 487                 if (!item)
 488                         re->dst_entry = insert_stage_data(re->pair->two->path,
 489                                         o_tree, a_tree, b_tree, entries);
 490                 else
 491                         re->dst_entry = item->util;
 492                 item = string_list_insert(renames, pair->one->path);
 493                 item->util = re;
 494         }
 495         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 496         diff_queued_diff.nr = 0;
 497         diff_flush(&opts);
 498         return renames;
 499 }
 500
 501 static int update_stages(const char *path, const struct diff_filespec *o,
 502                          const struct diff_filespec *a,
 503                          const struct diff_filespec *b)
 504 {
 505         int clear = 1;
 506         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_SKIP_DFCHECK;
 507         if (clear)
 508                 if (remove_file_from_cache(path))
 509                         return -1;
 510         if (o)
 511                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 512                         return -1;
 513         if (a)
 514                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 515                         return -1;
 516         if (b)
 517                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 518                         return -1;
 519         return 0;
 520 }
 521
 522 static void update_entry(struct stage_data *entry,
 523                          struct diff_filespec *o,
 524                          struct diff_filespec *a,
 525                          struct diff_filespec *b)
 526 {
 527         entry->processed = 0;
 528         entry->stages[1].mode = o->mode;
 529         entry->stages[2].mode = a->mode;
 530         entry->stages[3].mode = b->mode;
 531         hashcpy(entry->stages[1].sha, o->sha1);
 532         hashcpy(entry->stages[2].sha, a->sha1);
 533         hashcpy(entry->stages[3].sha, b->sha1);
 534 }
 535
 536 static int remove_file(struct merge_options *o, int clean,
 537                        const char *path, int no_wd)
 538 {
 539         int update_cache = o->call_depth || clean;
 540         int update_working_directory = !o->call_depth && !no_wd;
 541
 542         if (update_cache) {
 543                 if (remove_file_from_cache(path))
 544                         return -1;
 545         }
 546         if (update_working_directory) {
 547                 if (remove_path(path))
 548                         return -1;
 549         }
 550         return 0;
 551 }
 552
 553 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
 554 {
 555         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 556         int suffix = 0;
 557         struct stat st;
 558         char *p = newpath + strlen(path);
 559         strcpy(newpath, path);
 560         *(p++) = '~';
 561         strcpy(p, branch);
 562         for (; *p; ++p)
 563                 if ('/' == *p)
 564                         *p = '_';
 565         while (string_list_has_string(&o->current_file_set, newpath) ||
 566                string_list_has_string(&o->current_directory_set, newpath) ||
 567                lstat(newpath, &st) == 0)
 568                 sprintf(p, "_%d", suffix++);
 569
 570         string_list_insert(&o->current_file_set, newpath);
 571         return newpath;
 572 }
 573
 574 static void flush_buffer(int fd, const char *buf, unsigned long size)
 575 {
 576         while (size > 0) {
 577                 long ret = write_in_full(fd, buf, size);
 578                 if (ret < 0) {
 579                         /* Ignore epipe */
 580                         if (errno == EPIPE)
 581                                 break;
 582                         die_errno("merge-recursive");
 583                 } else if (!ret) {
 584                         die("merge-recursive: disk full?");
 585                 }
 586                 size -= ret;
 587                 buf += ret;
 588         }
 589 }
 590
 591 static int dir_in_way(const char *path, int check_working_copy)
 592 {
 593         int pos, pathlen = strlen(path);
 594         char *dirpath = xmalloc(pathlen + 2);
 595         struct stat st;
 596
 597         strcpy(dirpath, path);
 598         dirpath[pathlen] = '/';
 599         dirpath[pathlen+1] = '\0';
 600
 601         pos = cache_name_pos(dirpath, pathlen+1);
 602
 603         if (pos < 0)
 604                 pos = -1 - pos;
 605         if (pos < active_nr &&
 606             !strncmp(dirpath, active_cache[pos]->name, pathlen+1)) {
 607                 free(dirpath);
 608                 return 1;
 609         }
 610
 611         free(dirpath);
 612         return check_working_copy && !lstat(path, &st) && S_ISDIR(st.st_mode);
 613 }
 614
 615 static int was_tracked(const char *path)
 616 {
 617         int pos = cache_name_pos(path, strlen(path));
 618
 619         if (pos < 0)
 620                 pos = -1 - pos;
 621         while (pos < active_nr &&
 622                !strcmp(path, active_cache[pos]->name)) {
 623                 /*
 624                  * If stage #0, it is definitely tracked.
 625                  * If it has stage #2 then it was tracked
 626                  * before this merge started.  All other
 627                  * cases the path was not tracked.
 628                  */
 629                 switch (ce_stage(active_cache[pos])) {
 630                 case 0:
 631                 case 2:
 632                         return 1;
 633                 }
 634                 pos++;
 635         }
 636         return 0;
 637 }
 638
 639 static int would_lose_untracked(const char *path)
 640 {
 641         return !was_tracked(path) && file_exists(path);
 642 }
 643
 644 static int make_room_for_path(struct merge_options *o, const char *path)
 645 {
 646         int status, i;
 647         const char *msg = "failed to create path '%s'%s";
 648
 649         /* Unlink any D/F conflict files that are in the way */
 650         for (i = 0; i < o->df_conflict_file_set.nr; i++) {
 651                 const char *df_path = o->df_conflict_file_set.items[i].string;
 652                 size_t pathlen = strlen(path);
 653                 size_t df_pathlen = strlen(df_path);
 654                 if (df_pathlen < pathlen &&
 655                     path[df_pathlen] == '/' &&
 656                     strncmp(path, df_path, df_pathlen) == 0) {
 657                         output(o, 3,
 658                                "Removing %s to make room for subdirectory\n",
 659                                df_path);
 660                         unlink(df_path);
 661                         unsorted_string_list_delete_item(&o->df_conflict_file_set,
 662                                                          i, 0);
 663                         break;
 664                 }
 665         }
 666
 667         /* Make sure leading directories are created */
 668         status = safe_create_leading_directories_const(path);
 669         if (status) {
 670                 if (status == -3) {
 671                         /* something else exists */
 672                         error(msg, path, ": perhaps a D/F conflict?");
 673                         return -1;
 674                 }
 675                 die(msg, path, "");
 676         }
 677
 678         /*
 679          * Do not unlink a file in the work tree if we are not
 680          * tracking it.
 681          */
 682         if (would_lose_untracked(path))
 683                 return error("refusing to lose untracked file at '%s'",
 684                              path);
 685
 686         /* Successful unlink is good.. */
 687         if (!unlink(path))
 688                 return 0;
 689         /* .. and so is no existing file */
 690         if (errno == ENOENT)
 691                 return 0;
 692         /* .. but not some other error (who really cares what?) */
 693         return error(msg, path, ": perhaps a D/F conflict?");
 694 }
 695
 696 static void update_file_flags(struct merge_options *o,
 697                               const unsigned char *sha,
 698                               unsigned mode,
 699                               const char *path,
 700                               int update_cache,
 701                               int update_wd)
 702 {
 703         if (o->call_depth)
 704                 update_wd = 0;
 705
 706         if (update_wd) {
 707                 enum object_type type;
 708                 void *buf;
 709                 unsigned long size;
 710
 711                 if (S_ISGITLINK(mode)) {
 712                         /*
 713                          * We may later decide to recursively descend into
 714                          * the submodule directory and update its index
 715                          * and/or work tree, but we do not do that now.
 716                          */
 717                         update_wd = 0;
 718                         goto update_index;
 719                 }
 720
 721                 buf = read_sha1_file(sha, &type, &size);
 722                 if (!buf)
 723                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 724                 if (type != OBJ_BLOB)
 725                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 726                 if (S_ISREG(mode)) {
 727                         struct strbuf strbuf = STRBUF_INIT;
 728                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
 729                                 free(buf);
 730                                 size = strbuf.len;
 731                                 buf = strbuf_detach(&strbuf, NULL);
 732                         }
 733                 }
 734
 735                 if (make_room_for_path(o, path) < 0) {
 736                         update_wd = 0;
 737                         free(buf);
 738                         goto update_index;
 739                 }
 740                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 741                         int fd;
 742                         if (mode & 0100)
 743                                 mode = 0777;
 744                         else
 745                                 mode = 0666;
 746                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 747                         if (fd < 0)
 748                                 die_errno("failed to open '%s'", path);
 749                         flush_buffer(fd, buf, size);
 750                         close(fd);
 751                 } else if (S_ISLNK(mode)) {
 752                         char *lnk = xmemdupz(buf, size);
 753                         safe_create_leading_directories_const(path);
 754                         unlink(path);
 755                         if (symlink(lnk, path))
 756                                 die_errno("failed to symlink '%s'", path);
 757                         free(lnk);
 758                 } else
 759                         die("do not know what to do with %06o %s '%s'",
 760                             mode, sha1_to_hex(sha), path);
 761                 free(buf);
 762         }
 763  update_index:
 764         if (update_cache)
 765                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 766 }
 767
 768 static void update_file(struct merge_options *o,
 769                         int clean,
 770                         const unsigned char *sha,
 771                         unsigned mode,
 772                         const char *path)
 773 {
 774         update_file_flags(o, sha, mode, path, o->call_depth || clean, !o->call_depth);
 775 }
 776
 777 /* Low level file merging, update and removal */
 778
 779 struct merge_file_info {
 780         unsigned char sha[20];
 781         unsigned mode;
 782         unsigned clean:1,
 783                  merge:1;
 784 };
 785
 786 static int merge_3way(struct merge_options *o,
 787                       mmbuffer_t *result_buf,
 788                       const struct diff_filespec *one,
 789                       const struct diff_filespec *a,
 790                       const struct diff_filespec *b,
 791                       const char *branch1,
 792                       const char *branch2)
 793 {
 794         mmfile_t orig, src1, src2;
 795         struct ll_merge_options ll_opts = {0};
 796         char *base_name, *name1, *name2;
 797         int merge_status;
 798
 799         ll_opts.renormalize = o->renormalize;
 800         ll_opts.xdl_opts = o->xdl_opts;
 801
 802         if (o->call_depth) {
 803                 ll_opts.virtual_ancestor = 1;
 804                 ll_opts.variant = 0;
 805         } else {
 806                 switch (o->recursive_variant) {
 807                 case MERGE_RECURSIVE_OURS:
 808                         ll_opts.variant = XDL_MERGE_FAVOR_OURS;
 809                         break;
 810                 case MERGE_RECURSIVE_THEIRS:
 811                         ll_opts.variant = XDL_MERGE_FAVOR_THEIRS;
 812                         break;
 813                 default:
 814                         ll_opts.variant = 0;
 815                         break;
 816                 }
 817         }
 818
 819         if (strcmp(a->path, b->path) ||
 820             (o->ancestor != NULL && strcmp(a->path, one->path) != 0)) {
 821                 base_name = o->ancestor == NULL ? NULL :
 822                         xstrdup(mkpath("%s:%s", o->ancestor, one->path));
 823                 name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 824                 name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 825         } else {
 826                 base_name = o->ancestor == NULL ? NULL :
 827                         xstrdup(mkpath("%s", o->ancestor));
 828                 name1 = xstrdup(mkpath("%s", branch1));
 829                 name2 = xstrdup(mkpath("%s", branch2));
 830         }
 831
 832         read_mmblob(&orig, one->sha1);
 833         read_mmblob(&src1, a->sha1);
 834         read_mmblob(&src2, b->sha1);
 835
 836         merge_status = ll_merge(result_buf, a->path, &orig, base_name,
 837                                 &src1, name1, &src2, name2, &ll_opts);
 838
 839         free(name1);
 840         free(name2);
 841         free(orig.ptr);
 842         free(src1.ptr);
 843         free(src2.ptr);
 844         return merge_status;
 845 }
 846
 847 static struct merge_file_info merge_file_1(struct merge_options *o,
 848                                            const struct diff_filespec *one,
 849                                            const struct diff_filespec *a,
 850                                            const struct diff_filespec *b,
 851                                            const char *branch1,
 852                                            const char *branch2)
 853 {
 854         struct merge_file_info result;
 855         result.merge = 0;
 856         result.clean = 1;
 857
 858         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 859                 result.clean = 0;
 860                 if (S_ISREG(a->mode)) {
 861                         result.mode = a->mode;
 862                         hashcpy(result.sha, a->sha1);
 863                 } else {
 864                         result.mode = b->mode;
 865                         hashcpy(result.sha, b->sha1);
 866                 }
 867         } else {
 868                 if (!sha_eq(a->sha1, one->sha1) && !sha_eq(b->sha1, one->sha1))
 869                         result.merge = 1;
 870
 871                 /*
 872                  * Merge modes
 873                  */
 874                 if (a->mode == b->mode || a->mode == one->mode)
 875                         result.mode = b->mode;
 876                 else {
 877                         result.mode = a->mode;
 878                         if (b->mode != one->mode) {
 879                                 result.clean = 0;
 880                                 result.merge = 1;
 881                         }
 882                 }
 883
 884                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, one->sha1))
 885                         hashcpy(result.sha, b->sha1);
 886                 else if (sha_eq(b->sha1, one->sha1))
 887                         hashcpy(result.sha, a->sha1);
 888                 else if (S_ISREG(a->mode)) {
 889                         mmbuffer_t result_buf;
 890                         int merge_status;
 891
 892                         merge_status = merge_3way(o, &result_buf, one, a, b,
 893                                                   branch1, branch2);
 894
 895                         if ((merge_status < 0) || !result_buf.ptr)
 896                                 die("Failed to execute internal merge");
 897
 898                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 899                                             blob_type, result.sha))
 900                                 die("Unable to add %s to database",
 901                                     a->path);
 902
 903                         free(result_buf.ptr);
 904                         result.clean = (merge_status == 0);
 905                 } else if (S_ISGITLINK(a->mode)) {
 906                         result.clean = merge_submodule(result.sha, one->path, one->sha1,
 907                                                        a->sha1, b->sha1);
 908                 } else if (S_ISLNK(a->mode)) {
 909                         hashcpy(result.sha, a->sha1);
 910
 911                         if (!sha_eq(a->sha1, b->sha1))
 912                                 result.clean = 0;
 913                 } else {
 914                         die("unsupported object type in the tree");
 915                 }
 916         }
 917
 918         return result;
 919 }
 920
 921 static struct merge_file_info merge_file(struct merge_options *o,
 922                                          const char *path,
 923                                          const unsigned char *o_sha, int o_mode,
 924                                          const unsigned char *a_sha, int a_mode,
 925                                          const unsigned char *b_sha, int b_mode,
 926                                          const char *branch1,
 927                                          const char *branch2)
 928 {
 929         struct diff_filespec one, a, b;
 930
 931         one.path = a.path = b.path = (char *)path;
 932         hashcpy(one.sha1, o_sha);
 933         one.mode = o_mode;
 934         hashcpy(a.sha1, a_sha);
 935         a.mode = a_mode;
 936         hashcpy(b.sha1, b_sha);
 937         b.mode = b_mode;
 938         return merge_file_1(o, &one, &a, &b, branch1, branch2);
 939 }
 940
 941 static void conflict_rename_delete(struct merge_options *o,
 942                                    struct diff_filepair *pair,
 943                                    const char *rename_branch,
 944                                    const char *other_branch)
 945 {
 946         char *dest_name = pair->two->path;
 947         int df_conflict = 0;
 948
 949         output(o, 1, "CONFLICT (rename/delete): Rename %s->%s in %s "
 950                "and deleted in %s",
 951                pair->one->path, pair->two->path, rename_branch,
 952                other_branch);
 953         if (!o->call_depth)
 954                 update_stages(dest_name, NULL,
 955                               rename_branch == o->branch1 ? pair->two : NULL,
 956                               rename_branch == o->branch1 ? NULL : pair->two);
 957         if (dir_in_way(dest_name, !o->call_depth)) {
 958                 dest_name = unique_path(o, dest_name, rename_branch);
 959                 df_conflict = 1;
 960         }
 961         update_file(o, 0, pair->two->sha1, pair->two->mode, dest_name);
 962         if (df_conflict)
 963                 free(dest_name);
 964 }
 965
 966 static void conflict_rename_rename_1to2(struct merge_options *o,
 967                                         struct rename_conflict_info *ci)
 968 {
 969         /* One file was renamed in both branches, but to different names. */
 970         struct diff_filespec *one = ci->pair1->one;
 971         struct diff_filespec *a = ci->pair1->two;
 972         struct diff_filespec *b = ci->pair2->two;
 973         const char *dst_name_a = a->path;
 974         const char *dst_name_b = b->path;
 975         char *del[2];
 976         int delp = 0;
 977
 978         output(o, 1, "CONFLICT (rename/rename): "
 979                "Rename \"%s\"->\"%s\" in branch \"%s\" "
 980                "rename \"%s\"->\"%s\" in \"%s\"%s",
 981                one->path, a->path, ci->branch1,
 982                one->path, b->path, ci->branch2,
 983                o->call_depth ? " (left unresolved)" : "");
 984         if (dir_in_way(a->path, !o->call_depth)) {
 985                 dst_name_a = del[delp++] = unique_path(o, a->path, ci->branch1);
 986                 output(o, 1, "%s is a directory in %s adding as %s instead",
 987                        a->path, ci->branch2, dst_name_a);
 988         }
 989         if (dir_in_way(b->path, !o->call_depth)) {
 990                 dst_name_b = del[delp++] = unique_path(o, b->path, ci->branch2);
 991                 output(o, 1, "%s is a directory in %s adding as %s instead",
 992                        b->path, ci->branch1, dst_name_b);
 993         }
 994         if (o->call_depth) {
 995                 struct merge_file_info mfi;
 996                 mfi = merge_file(o, one->path,
 997                                  one->sha1, one->mode,
 998                                  a->sha1, a->mode,
 999                                  b->sha1, b->mode,
1000                                  ci->branch1, ci->branch2);
1001                 /*
1002                  * FIXME: For rename/add-source conflicts (if we could detect
1003                  * such), this is wrong.  We should instead find a unique
1004                  * pathname and then either rename the add-source file to that
1005                  * unique path, or use that unique path instead of src here.
1006                  */
1007                 update_file(o, 0, mfi.sha, mfi.mode, one->path);
1008                 remove_file_from_cache(a->path);
1009                 remove_file_from_cache(b->path);
1010         } else {
1011                 update_stages(a->path, NULL, a, NULL);
1012                 update_stages(b->path, NULL, NULL, b);
1013
1014                 update_file(o, 0, a->sha1, a->mode, dst_name_a);
1015                 update_file(o, 0, b->sha1, b->mode, dst_name_b);
1016         }
1017         while (delp--)
1018                 free(del[delp]);
1019 }
1020
1021 static void conflict_rename_rename_2to1(struct merge_options *o,
1022                                         struct rename *ren1,
1023                                         const char *branch1,
1024                                         struct rename *ren2,
1025                                         const char *branch2)
1026 {
1027         char *path = ren1->pair->two->path; /* same as ren2->pair->two->path */
1028         /* Two files were renamed to the same thing. */
1029         if (o->call_depth) {
1030                 struct merge_file_info mfi;
1031                 mfi = merge_file(o, path, null_sha1, 0,
1032                                  ren1->pair->two->sha1, ren1->pair->two->mode,
1033                                  ren2->pair->two->sha1, ren2->pair->two->mode,
1034                                  branch1, branch2);
1035                 output(o, 1, "Adding merged %s", path);
1036                 update_file(o, 0, mfi.sha, mfi.mode, path);
1037         } else {
1038                 char *new_path1 = unique_path(o, path, branch1);
1039                 char *new_path2 = unique_path(o, path, branch2);
1040                 output(o, 1, "Renaming %s to %s and %s to %s instead",
1041                        ren1->pair->one->path, new_path1,
1042                        ren2->pair->one->path, new_path2);
1043                 remove_file(o, 0, path, 0);
1044                 update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode,
1045                             new_path1);
1046                 update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode,
1047                             new_path2);
1048                 free(new_path2);
1049                 free(new_path1);
1050         }
1051 }
1052
1053 static int process_renames(struct merge_options *o,
1054                            struct string_list *a_renames,
1055                            struct string_list *b_renames)
1056 {
1057         int clean_merge = 1, i, j;
1058         struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
1059         struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
1060         const struct rename *sre;
1061
1062         for (i = 0; i < a_renames->nr; i++) {
1063                 sre = a_renames->items[i].util;
1064                 string_list_insert(&a_by_dst, sre->pair->two->path)->util
1065                         = (void *)sre;
1066         }
1067         for (i = 0; i < b_renames->nr; i++) {
1068                 sre = b_renames->items[i].util;
1069                 string_list_insert(&b_by_dst, sre->pair->two->path)->util
1070                         = (void *)sre;
1071         }
1072
1073         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
1074                 struct string_list *renames1, *renames2Dst;
1075                 struct rename *ren1 = NULL, *ren2 = NULL;
1076                 const char *branch1, *branch2;
1077                 const char *ren1_src, *ren1_dst;
1078
1079                 if (i >= a_renames->nr) {
1080                         ren2 = b_renames->items[j++].util;
1081                 } else if (j >= b_renames->nr) {
1082                         ren1 = a_renames->items[i++].util;
1083                 } else {
1084                         int compare = strcmp(a_renames->items[i].string,
1085                                              b_renames->items[j].string);
1086                         if (compare <= 0)
1087                                 ren1 = a_renames->items[i++].util;
1088                         if (compare >= 0)
1089                                 ren2 = b_renames->items[j++].util;
1090                 }
1091
1092                 /* TODO: refactor, so that 1/2 are not needed */
1093                 if (ren1) {
1094                         renames1 = a_renames;
1095                         renames2Dst = &b_by_dst;
1096                         branch1 = o->branch1;
1097                         branch2 = o->branch2;
1098                 } else {
1099                         struct rename *tmp;
1100                         renames1 = b_renames;
1101                         renames2Dst = &a_by_dst;
1102                         branch1 = o->branch2;
1103                         branch2 = o->branch1;
1104                         tmp = ren2;
1105                         ren2 = ren1;
1106                         ren1 = tmp;
1107                 }
1108
1109                 ren1->dst_entry->processed = 1;
1110                 /* BUG: We should only mark src_entry as processed if we
1111                  * are not dealing with a rename + add-source case.
1112                  */
1113                 ren1->src_entry->processed = 1;
1114
1115                 if (ren1->processed)
1116                         continue;
1117                 ren1->processed = 1;
1118
1119                 ren1_src = ren1->pair->one->path;
1120                 ren1_dst = ren1->pair->two->path;
1121
1122                 if (ren2) {
1123                         const char *ren2_src = ren2->pair->one->path;
1124                         const char *ren2_dst = ren2->pair->two->path;
1125                         enum rename_type rename_type;
1126                         /* Renamed in 1 and renamed in 2 */
1127                         if (strcmp(ren1_src, ren2_src) != 0)
1128                                 die("ren1.src != ren2.src");
1129                         ren2->dst_entry->processed = 1;
1130                         ren2->processed = 1;
1131                         if (strcmp(ren1_dst, ren2_dst) != 0) {
1132                                 rename_type = RENAME_ONE_FILE_TO_TWO;
1133                         } else {
1134                                 rename_type = RENAME_ONE_FILE_TO_ONE;
1135                                 /* BUG: We should only remove ren1_src in
1136                                  * the base stage (think of rename +
1137                                  * add-source cases).
1138                                  */
1139                                 remove_file(o, 1, ren1_src, 1);
1140                                 update_entry(ren1->dst_entry,
1141                                              ren1->pair->one,
1142                                              ren1->pair->two,
1143                                              ren2->pair->two);
1144                         }
1145                         setup_rename_conflict_info(rename_type,
1146                                                    ren1->pair,
1147                                                    ren2->pair,
1148                                                    branch1,
1149                                                    branch2,
1150                                                    ren1->dst_entry,
1151                                                    ren2->dst_entry);
1152                 } else {
1153                         /* Renamed in 1, maybe changed in 2 */
1154                         struct string_list_item *item;
1155                         /* we only use sha1 and mode of these */
1156                         struct diff_filespec src_other, dst_other;
1157                         int try_merge;
1158
1159                         /*
1160                          * unpack_trees loads entries from common-commit
1161                          * into stage 1, from head-commit into stage 2, and
1162                          * from merge-commit into stage 3.  We keep track
1163                          * of which side corresponds to the rename.
1164                          */
1165                         int renamed_stage = a_renames == renames1 ? 2 : 3;
1166                         int other_stage =   a_renames == renames1 ? 3 : 2;
1167
1168                         /* BUG: We should only remove ren1_src in the base
1169                          * stage and in other_stage (think of rename +
1170                          * add-source case).
1171                          */
1172                         remove_file(o, 1, ren1_src,
1173                                     renamed_stage == 2 || !was_tracked(ren1_src));
1174
1175                         hashcpy(src_other.sha1, ren1->src_entry->stages[other_stage].sha);
1176                         src_other.mode = ren1->src_entry->stages[other_stage].mode;
1177                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[other_stage].sha);
1178                         dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
1179                         try_merge = 0;
1180
1181                         if (sha_eq(src_other.sha1, null_sha1)) {
1182                                 setup_rename_conflict_info(RENAME_DELETE,
1183                                                            ren1->pair,
1184                                                            NULL,
1185                                                            branch1,
1186                                                            branch2,
1187                                                            ren1->dst_entry,
1188                                                            NULL);
1189                         } else if ((item = string_list_lookup(renames2Dst, ren1_dst))) {
1190                                 char *ren2_src, *ren2_dst;
1191                                 ren2 = item->util;
1192                                 ren2_src = ren2->pair->one->path;
1193                                 ren2_dst = ren2->pair->two->path;
1194
1195                                 clean_merge = 0;
1196                                 ren2->processed = 1;
1197                                 remove_file(o, 1, ren2_src,
1198                                             renamed_stage == 3 || would_lose_untracked(ren1_src));
1199
1200                                 output(o, 1, "CONFLICT (rename/rename): "
1201                                        "Rename %s->%s in %s. "
1202                                        "Rename %s->%s in %s",
1203                                        ren1_src, ren1_dst, branch1,
1204                                        ren2_src, ren2_dst, branch2);
1205                                 conflict_rename_rename_2to1(o, ren1, branch1, ren2, branch2);
1206                         } else if ((dst_other.mode == ren1->pair->two->mode) &&
1207                                    sha_eq(dst_other.sha1, ren1->pair->two->sha1)) {
1208                                 /* Added file on the other side
1209                                    identical to the file being
1210                                    renamed: clean merge */
1211                                 update_file(o, 1, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
1212                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
1213                                 clean_merge = 0;
1214                                 try_merge = 1;
1215                                 output(o, 1, "CONFLICT (rename/add): Rename %s->%s in %s. "
1216                                        "%s added in %s",
1217                                        ren1_src, ren1_dst, branch1,
1218                                        ren1_dst, branch2);
1219                                 if (o->call_depth) {
1220                                         struct merge_file_info mfi;
1221                                         mfi = merge_file(o, ren1_dst, null_sha1, 0,
1222                                                          ren1->pair->two->sha1, ren1->pair->two->mode,
1223                                                          dst_other.sha1, dst_other.mode,
1224                                                          branch1, branch2);
1225                                         output(o, 1, "Adding merged %s", ren1_dst);
1226                                         update_file(o, 0, mfi.sha, mfi.mode, ren1_dst);
1227                                         try_merge = 0;
1228                                 } else {
1229                                         char *new_path = unique_path(o, ren1_dst, branch2);
1230                                         output(o, 1, "Adding as %s instead", new_path);
1231                                         update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
1232                                         free(new_path);
1233                                 }
1234                         } else
1235                                 try_merge = 1;
1236
1237                         if (try_merge) {
1238                                 struct diff_filespec *one, *a, *b;
1239                                 src_other.path = (char *)ren1_src;
1240
1241                                 one = ren1->pair->one;
1242                                 if (a_renames == renames1) {
1243                                         a = ren1->pair->two;
1244                                         b = &src_other;
1245                                 } else {
1246                                         b = ren1->pair->two;
1247                                         a = &src_other;
1248                                 }
1249                                 update_entry(ren1->dst_entry, one, a, b);
1250                                 setup_rename_conflict_info(RENAME_NORMAL,
1251                                                            ren1->pair,
1252                                                            NULL,
1253                                                            branch1,
1254                                                            NULL,
1255                                                            ren1->dst_entry,
1256                                                            NULL);
1257                         }
1258                 }
1259         }
1260         string_list_clear(&a_by_dst, 0);
1261         string_list_clear(&b_by_dst, 0);
1262
1263         return clean_merge;
1264 }
1265
1266 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1267 {
1268         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1269 }
1270
1271 static int read_sha1_strbuf(const unsigned char *sha1, struct strbuf *dst)
1272 {
1273         void *buf;
1274         enum object_type type;
1275         unsigned long size;
1276         buf = read_sha1_file(sha1, &type, &size);
1277         if (!buf)
1278                 return error("cannot read object %s", sha1_to_hex(sha1));
1279         if (type != OBJ_BLOB) {
1280                 free(buf);
1281                 return error("object %s is not a blob", sha1_to_hex(sha1));
1282         }
1283         strbuf_attach(dst, buf, size, size + 1);
1284         return 0;
1285 }
1286
1287 static int blob_unchanged(const unsigned char *o_sha,
1288                           const unsigned char *a_sha,
1289                           int renormalize, const char *path)
1290 {
1291         struct strbuf o = STRBUF_INIT;
1292         struct strbuf a = STRBUF_INIT;
1293         int ret = 0; /* assume changed for safety */
1294
1295         if (sha_eq(o_sha, a_sha))
1296                 return 1;
1297         if (!renormalize)
1298                 return 0;
1299
1300         assert(o_sha && a_sha);
1301         if (read_sha1_strbuf(o_sha, &o) || read_sha1_strbuf(a_sha, &a))
1302                 goto error_return;
1303         /*
1304          * Note: binary | is used so that both renormalizations are
1305          * performed.  Comparison can be skipped if both files are
1306          * unchanged since their sha1s have already been compared.
1307          */
1308         if (renormalize_buffer(path, o.buf, o.len, &o) |
1309             renormalize_buffer(path, a.buf, o.len, &a))
1310                 ret = (o.len == a.len && !memcmp(o.buf, a.buf, o.len));
1311
1312 error_return:
1313         strbuf_release(&o);
1314         strbuf_release(&a);
1315         return ret;
1316 }
1317
1318 static void handle_delete_modify(struct merge_options *o,
1319                                  const char *path,
1320                                  unsigned char *o_sha, int o_mode,
1321                                  unsigned char *a_sha, int a_mode,
1322                                  unsigned char *b_sha, int b_mode)
1323 {
1324         char *renamed = NULL;
1325         if (dir_in_way(path, !o->call_depth)) {
1326                 renamed = unique_path(o, path, a_sha ? o->branch1 : o->branch2);
1327         }
1328
1329         if (o->call_depth) {
1330                 /*
1331                  * We cannot arbitrarily accept either a_sha or b_sha as
1332                  * correct; since there is no true "middle point" between
1333                  * them, simply reuse the base version for virtual merge base.
1334                  */
1335                 remove_file_from_cache(path);
1336                 update_file(o, 0, o_sha, o_mode, renamed ? renamed : path);
1337         } else if (!a_sha) {
1338                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1339                        "and modified in %s. Version %s of %s left in tree%s%s.",
1340                        path, o->branch1,
1341                        o->branch2, o->branch2, path,
1342                        NULL == renamed ? "" : " at ",
1343                        NULL == renamed ? "" : renamed);
1344                 update_file(o, 0, b_sha, b_mode, renamed ? renamed : path);
1345         } else {
1346                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1347                        "and modified in %s. Version %s of %s left in tree%s%s.",
1348                        path, o->branch2,
1349                        o->branch1, o->branch1, path,
1350                        NULL == renamed ? "" : " at ",
1351                        NULL == renamed ? "" : renamed);
1352                 update_file(o, 0, a_sha, a_mode, renamed ? renamed : path);
1353         }
1354         free(renamed);
1355
1356 }
1357
1358 static int merge_content(struct merge_options *o,
1359                          const char *path,
1360                          unsigned char *o_sha, int o_mode,
1361                          unsigned char *a_sha, int a_mode,
1362                          unsigned char *b_sha, int b_mode,
1363                          struct rename_conflict_info *rename_conflict_info)
1364 {
1365         const char *reason = "content";
1366         char *side1 = NULL, *side2 = NULL;
1367         const char *path1 = NULL, *path2 = NULL;
1368         struct merge_file_info mfi;
1369         struct diff_filespec one, a, b;
1370         unsigned df_conflict_remains = 0;
1371
1372         if (!o_sha) {
1373                 reason = "add/add";
1374                 o_sha = (unsigned char *)null_sha1;
1375         }
1376         one.path = a.path = b.path = (char *)path;
1377         hashcpy(one.sha1, o_sha);
1378         one.mode = o_mode;
1379         hashcpy(a.sha1, a_sha);
1380         a.mode = a_mode;
1381         hashcpy(b.sha1, b_sha);
1382         b.mode = b_mode;
1383
1384         if (rename_conflict_info) {
1385                 struct diff_filepair *pair1 = rename_conflict_info->pair1;
1386
1387                 path1 = (o->branch1 == rename_conflict_info->branch1) ?
1388                         pair1->two->path : pair1->one->path;
1389                 /* If rename_conflict_info->pair2 != NULL, we are in
1390                  * RENAME_ONE_FILE_TO_ONE case.  Otherwise, we have a
1391                  * normal rename.
1392                  */
1393                 path2 = (rename_conflict_info->pair2 ||
1394                          o->branch2 == rename_conflict_info->branch1) ?
1395                         pair1->two->path : pair1->one->path;
1396                 side1 = xmalloc(strlen(o->branch1) + strlen(path1) + 2);
1397                 side2 = xmalloc(strlen(o->branch2) + strlen(path2) + 2);
1398                 sprintf(side1, "%s:%s", o->branch1, path1);
1399                 sprintf(side2, "%s:%s", o->branch2, path2);
1400
1401                 if (dir_in_way(path, !o->call_depth))
1402                         df_conflict_remains = 1;
1403         }
1404         mfi = merge_file_1(o, &one, &a, &b,
1405                            side1 ? side1 : o->branch1, side2 ? side2 : o->branch2);
1406         free(side1);
1407         free(side2);
1408
1409         if (mfi.clean && !df_conflict_remains &&
1410             sha_eq(mfi.sha, a_sha) && mfi.mode == a_mode) {
1411                 int path_renamed_outside_HEAD;
1412                 output(o, 3, "Skipped %s (merged same as existing)", path);
1413                 /*
1414                  * The content merge resulted in the same file contents we
1415                  * already had.  We can return early if those file contents
1416                  * are recorded at the correct path (which may not be true
1417                  * if the merge involves a rename).
1418                  */
1419                 path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
1420                 if (!path_renamed_outside_HEAD) {
1421                         add_cacheinfo(mfi.mode, mfi.sha, path,
1422                                       0 /*stage*/, 1 /*refresh*/, 0 /*options*/);
1423                         return mfi.clean;
1424                 }
1425         } else
1426                 output(o, 2, "Auto-merging %s", path);
1427
1428         if (!mfi.clean) {
1429                 if (S_ISGITLINK(mfi.mode))
1430                         reason = "submodule";
1431                 output(o, 1, "CONFLICT (%s): Merge conflict in %s",
1432                                 reason, path);
1433                 if (rename_conflict_info && !df_conflict_remains)
1434                         update_stages(path, &one, &a, &b);
1435         }
1436
1437         if (df_conflict_remains) {
1438                 char *new_path;
1439                 if (o->call_depth) {
1440                         remove_file_from_cache(path);
1441                 } else {
1442                         if (!mfi.clean)
1443                                 update_stages(path, &one, &a, &b);
1444                         else {
1445                                 int file_from_stage2 = was_tracked(path);
1446                                 struct diff_filespec merged;
1447                                 hashcpy(merged.sha1, mfi.sha);
1448                                 merged.mode = mfi.mode;
1449
1450                                 update_stages(path, NULL,
1451                                               file_from_stage2 ? &merged : NULL,
1452                                               file_from_stage2 ? NULL : &merged);
1453                         }
1454
1455                 }
1456                 new_path = unique_path(o, path, rename_conflict_info->branch1);
1457                 output(o, 1, "Adding as %s instead", new_path);
1458                 update_file(o, 0, mfi.sha, mfi.mode, new_path);
1459                 free(new_path);
1460                 mfi.clean = 0;
1461         } else {
1462                 update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
1463         }
1464         return mfi.clean;
1465
1466 }
1467
1468 /* Per entry merge function */
1469 static int process_entry(struct merge_options *o,
1470                          const char *path, struct stage_data *entry)
1471 {
1472         /*
1473         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1474         print_index_entry("\tpath: ", entry);
1475         */
1476         int clean_merge = 1;
1477         int normalize = o->renormalize;
1478         unsigned o_mode = entry->stages[1].mode;
1479         unsigned a_mode = entry->stages[2].mode;
1480         unsigned b_mode = entry->stages[3].mode;
1481         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1482         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1483         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1484
1485         entry->processed = 1;
1486         if (entry->rename_conflict_info) {
1487                 struct rename_conflict_info *conflict_info = entry->rename_conflict_info;
1488                 switch (conflict_info->rename_type) {
1489                 case RENAME_NORMAL:
1490                 case RENAME_ONE_FILE_TO_ONE:
1491                         clean_merge = merge_content(o, path,
1492                                                     o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
1493                                                     conflict_info);
1494                         break;
1495                 case RENAME_DELETE:
1496                         clean_merge = 0;
1497                         conflict_rename_delete(o, conflict_info->pair1,
1498                                                conflict_info->branch1,
1499                                                conflict_info->branch2);
1500                         break;
1501                 case RENAME_ONE_FILE_TO_TWO:
1502                         clean_merge = 0;
1503                         conflict_rename_rename_1to2(o, conflict_info);
1504                         break;
1505                 default:
1506                         entry->processed = 0;
1507                         break;
1508                 }
1509         } else if (o_sha && (!a_sha || !b_sha)) {
1510                 /* Case A: Deleted in one */
1511                 if ((!a_sha && !b_sha) ||
1512                     (!b_sha && blob_unchanged(o_sha, a_sha, normalize, path)) ||
1513                     (!a_sha && blob_unchanged(o_sha, b_sha, normalize, path))) {
1514                         /* Deleted in both or deleted in one and
1515                          * unchanged in the other */
1516                         if (a_sha)
1517                                 output(o, 2, "Removing %s", path);
1518                         /* do not touch working file if it did not exist */
1519                         remove_file(o, 1, path, !a_sha);
1520                 } else {
1521                         /* Modify/delete; deleted side may have put a directory in the way */
1522                         clean_merge = 0;
1523                         handle_delete_modify(o, path, o_sha, o_mode,
1524                                              a_sha, a_mode, b_sha, b_mode);
1525                 }
1526         } else if ((!o_sha && a_sha && !b_sha) ||
1527                    (!o_sha && !a_sha && b_sha)) {
1528                 /* Case B: Added in one. */
1529                 /* [nothing|directory] -> ([nothing|directory], file) */
1530
1531                 const char *add_branch;
1532                 const char *other_branch;
1533                 unsigned mode;
1534                 const unsigned char *sha;
1535                 const char *conf;
1536
1537                 if (a_sha) {
1538                         add_branch = o->branch1;
1539                         other_branch = o->branch2;
1540                         mode = a_mode;
1541                         sha = a_sha;
1542                         conf = "file/directory";
1543                 } else {
1544                         add_branch = o->branch2;
1545                         other_branch = o->branch1;
1546                         mode = b_mode;
1547                         sha = b_sha;
1548                         conf = "directory/file";
1549                 }
1550                 if (dir_in_way(path, !o->call_depth)) {
1551                         char *new_path = unique_path(o, path, add_branch);
1552                         clean_merge = 0;
1553                         output(o, 1, "CONFLICT (%s): There is a directory with name %s in %s. "
1554                                "Adding %s as %s",
1555                                conf, path, other_branch, path, new_path);
1556                         if (o->call_depth)
1557                                 remove_file_from_cache(path);
1558                         update_file(o, 0, sha, mode, new_path);
1559                         if (o->call_depth)
1560                                 remove_file_from_cache(path);
1561                         free(new_path);
1562                 } else {
1563                         output(o, 2, "Adding %s", path);
1564                         update_file(o, 1, sha, mode, path);
1565                 }
1566         } else if (a_sha && b_sha) {
1567                 /* Case C: Added in both (check for same permissions) and */
1568                 /* case D: Modified in both, but differently. */
1569                 clean_merge = merge_content(o, path,
1570                                             o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
1571                                             NULL);
1572         } else if (!o_sha && !a_sha && !b_sha) {
1573                 /*
1574                  * this entry was deleted altogether. a_mode == 0 means
1575                  * we had that path and want to actively remove it.
1576                  */
1577                 remove_file(o, 1, path, !a_mode);
1578         } else
1579                 die("Fatal merge failure, shouldn't happen.");
1580
1581         return clean_merge;
1582 }
1583
1584 int merge_trees(struct merge_options *o,
1585                 struct tree *head,
1586                 struct tree *merge,
1587                 struct tree *common,
1588                 struct tree **result)
1589 {
1590         int code, clean;
1591
1592         if (o->subtree_shift) {
1593                 merge = shift_tree_object(head, merge, o->subtree_shift);
1594                 common = shift_tree_object(head, common, o->subtree_shift);
1595         }
1596
1597         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1598                 output(o, 0, "Already up-to-date!");
1599                 *result = head;
1600                 return 1;
1601         }
1602
1603         code = git_merge_trees(o->call_depth, common, head, merge);
1604
1605         if (code != 0) {
1606                 if (show(o, 4) || o->call_depth)
1607                         die("merging of trees %s and %s failed",
1608                             sha1_to_hex(head->object.sha1),
1609                             sha1_to_hex(merge->object.sha1));
1610                 else
1611                         exit(128);
1612         }
1613
1614         if (unmerged_cache()) {
1615                 struct string_list *entries, *re_head, *re_merge;
1616                 int i;
1617                 string_list_clear(&o->current_file_set, 1);
1618                 string_list_clear(&o->current_directory_set, 1);
1619                 get_files_dirs(o, head);
1620                 get_files_dirs(o, merge);
1621
1622                 entries = get_unmerged();
1623                 record_df_conflict_files(o, entries);
1624                 re_head  = get_renames(o, head, common, head, merge, entries);
1625                 re_merge = get_renames(o, merge, common, head, merge, entries);
1626                 clean = process_renames(o, re_head, re_merge);
1627                 for (i = entries->nr-1; 0 <= i; i--) {
1628                         const char *path = entries->items[i].string;
1629                         struct stage_data *e = entries->items[i].util;
1630                         if (!e->processed
1631                                 && !process_entry(o, path, e))
1632                                 clean = 0;
1633                 }
1634                 for (i = 0; i < entries->nr; i++) {
1635                         struct stage_data *e = entries->items[i].util;
1636                         if (!e->processed)
1637                                 die("Unprocessed path??? %s",
1638                                     entries->items[i].string);
1639                 }
1640
1641                 string_list_clear(re_merge, 0);
1642                 string_list_clear(re_head, 0);
1643                 string_list_clear(entries, 1);
1644
1645         }
1646         else
1647                 clean = 1;
1648
1649         if (o->call_depth)
1650                 *result = write_tree_from_memory(o);
1651
1652         return clean;
1653 }
1654
1655 static struct commit_list *reverse_commit_list(struct commit_list *list)
1656 {
1657         struct commit_list *next = NULL, *current, *backup;
1658         for (current = list; current; current = backup) {
1659                 backup = current->next;
1660                 current->next = next;
1661                 next = current;
1662         }
1663         return next;
1664 }
1665
1666 /*
1667  * Merge the commits h1 and h2, return the resulting virtual
1668  * commit object and a flag indicating the cleanness of the merge.
1669  */
1670 int merge_recursive(struct merge_options *o,
1671                     struct commit *h1,
1672                     struct commit *h2,
1673                     struct commit_list *ca,
1674                     struct commit **result)
1675 {
1676         struct commit_list *iter;
1677         struct commit *merged_common_ancestors;
1678         struct tree *mrtree = mrtree;
1679         int clean;
1680
1681         if (show(o, 4)) {
1682                 output(o, 4, "Merging:");
1683                 output_commit_title(o, h1);
1684                 output_commit_title(o, h2);
1685         }
1686
1687         if (!ca) {
1688                 ca = get_merge_bases(h1, h2, 1);
1689                 ca = reverse_commit_list(ca);
1690         }
1691
1692         if (show(o, 5)) {
1693                 output(o, 5, "found %u common ancestor(s):", commit_list_count(ca));
1694                 for (iter = ca; iter; iter = iter->next)
1695                         output_commit_title(o, iter->item);
1696         }
1697
1698         merged_common_ancestors = pop_commit(&ca);
1699         if (merged_common_ancestors == NULL) {
1700                 /* if there is no common ancestor, make an empty tree */
1701                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1702
1703                 tree->object.parsed = 1;
1704                 tree->object.type = OBJ_TREE;
1705                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1706                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1707         }
1708
1709         for (iter = ca; iter; iter = iter->next) {
1710                 const char *saved_b1, *saved_b2;
1711                 o->call_depth++;
1712                 /*
1713                  * When the merge fails, the result contains files
1714                  * with conflict markers. The cleanness flag is
1715                  * ignored, it was never actually used, as result of
1716                  * merge_trees has always overwritten it: the committed
1717                  * "conflicts" were already resolved.
1718                  */
1719                 discard_cache();
1720                 saved_b1 = o->branch1;
1721                 saved_b2 = o->branch2;
1722                 o->branch1 = "Temporary merge branch 1";
1723                 o->branch2 = "Temporary merge branch 2";
1724                 merge_recursive(o, merged_common_ancestors, iter->item,
1725                                 NULL, &merged_common_ancestors);
1726                 o->branch1 = saved_b1;
1727                 o->branch2 = saved_b2;
1728                 o->call_depth--;
1729
1730                 if (!merged_common_ancestors)
1731                         die("merge returned no commit");
1732         }
1733
1734         discard_cache();
1735         if (!o->call_depth)
1736                 read_cache();
1737
1738         o->ancestor = "merged common ancestors";
1739         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
1740                             &mrtree);
1741
1742         if (o->call_depth) {
1743                 *result = make_virtual_commit(mrtree, "merged tree");
1744                 commit_list_insert(h1, &(*result)->parents);
1745                 commit_list_insert(h2, &(*result)->parents->next);
1746         }
1747         flush_output(o);
1748         if (show(o, 2))
1749                 diff_warn_rename_limit("merge.renamelimit",
1750                                        o->needed_rename_limit, 0);
1751         return clean;
1752 }
1753
1754 static struct commit *get_ref(const unsigned char *sha1, const char *name)
1755 {
1756         struct object *object;
1757
1758         object = deref_tag(parse_object(sha1), name, strlen(name));
1759         if (!object)
1760                 return NULL;
1761         if (object->type == OBJ_TREE)
1762                 return make_virtual_commit((struct tree*)object, name);
1763         if (object->type != OBJ_COMMIT)
1764                 return NULL;
1765         if (parse_commit((struct commit *)object))
1766                 return NULL;
1767         return (struct commit *)object;
1768 }
1769
1770 int merge_recursive_generic(struct merge_options *o,
1771                             const unsigned char *head,
1772                             const unsigned char *merge,
1773                             int num_base_list,
1774                             const unsigned char **base_list,
1775                             struct commit **result)
1776 {
1777         int clean, index_fd;
1778         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1779         struct commit *head_commit = get_ref(head, o->branch1);
1780         struct commit *next_commit = get_ref(merge, o->branch2);
1781         struct commit_list *ca = NULL;
1782
1783         if (base_list) {
1784                 int i;
1785                 for (i = 0; i < num_base_list; ++i) {
1786                         struct commit *base;
1787                         if (!(base = get_ref(base_list[i], sha1_to_hex(base_list[i]))))
1788                                 return error("Could not parse object '%s'",
1789                                         sha1_to_hex(base_list[i]));
1790                         commit_list_insert(base, &ca);
1791                 }
1792         }
1793
1794         index_fd = hold_locked_index(lock, 1);
1795         clean = merge_recursive(o, head_commit, next_commit, ca,
1796                         result);
1797         if (active_cache_changed &&
1798                         (write_cache(index_fd, active_cache, active_nr) ||
1799                          commit_locked_index(lock)))
1800                 return error("Unable to write index.");
1801
1802         return clean ? 0 : 1;
1803 }
1804
1805 static int merge_recursive_config(const char *var, const char *value, void *cb)
1806 {
1807         struct merge_options *o = cb;
1808         if (!strcmp(var, "merge.verbosity")) {
1809                 o->verbosity = git_config_int(var, value);
1810                 return 0;
1811         }
1812         if (!strcmp(var, "diff.renamelimit")) {
1813                 o->diff_rename_limit = git_config_int(var, value);
1814                 return 0;
1815         }
1816         if (!strcmp(var, "merge.renamelimit")) {
1817                 o->merge_rename_limit = git_config_int(var, value);
1818                 return 0;
1819         }
1820         return git_xmerge_config(var, value, cb);
1821 }
1822
1823 void init_merge_options(struct merge_options *o)
1824 {
1825         memset(o, 0, sizeof(struct merge_options));
1826         o->verbosity = 2;
1827         o->buffer_output = 1;
1828         o->diff_rename_limit = -1;
1829         o->merge_rename_limit = -1;
1830         o->renormalize = 0;
1831         git_config(merge_recursive_config, o);
1832         if (getenv("GIT_MERGE_VERBOSITY"))
1833                 o->verbosity =
1834                         strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1835         if (o->verbosity >= 5)
1836                 o->buffer_output = 0;
1837         strbuf_init(&o->obuf, 0);
1838         memset(&o->current_file_set, 0, sizeof(struct string_list));
1839         o->current_file_set.strdup_strings = 1;
1840         memset(&o->current_directory_set, 0, sizeof(struct string_list));
1841         o->current_directory_set.strdup_strings = 1;
1842         memset(&o->df_conflict_file_set, 0, sizeof(struct string_list));
1843         o->df_conflict_file_set.strdup_strings = 1;
1844 }
1845
1846 int parse_merge_opt(struct merge_options *o, const char *s)
1847 {
1848         if (!s || !*s)
1849                 return -1;
1850         if (!strcmp(s, "ours"))
1851                 o->recursive_variant = MERGE_RECURSIVE_OURS;
1852         else if (!strcmp(s, "theirs"))
1853                 o->recursive_variant = MERGE_RECURSIVE_THEIRS;
1854         else if (!strcmp(s, "subtree"))
1855                 o->subtree_shift = "";
1856         else if (!prefixcmp(s, "subtree="))
1857                 o->subtree_shift = s + strlen("subtree=");
1858         else if (!strcmp(s, "patience"))
1859                 o->xdl_opts |= XDF_PATIENCE_DIFF;
1860         else if (!strcmp(s, "ignore-space-change"))
1861                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_CHANGE;
1862         else if (!strcmp(s, "ignore-all-space"))
1863                 o->xdl_opts |= XDF_IGNORE_WHITESPACE;
1864         else if (!strcmp(s, "ignore-space-at-eol"))
1865                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_AT_EOL;
1866         else if (!strcmp(s, "renormalize"))
1867                 o->renormalize = 1;
1868         else if (!strcmp(s, "no-renormalize"))
1869                 o->renormalize = 0;
1870         else if (!prefixcmp(s, "rename-threshold=")) {
1871                 const char *score = s + strlen("rename-threshold=");
1872                 if ((o->rename_score = parse_rename_score(&score)) == -1 || *score != 0)
1873                         return -1;
1874         }
1875         else
1876                 return -1;
1877         return 0;
1878 }