git.oblomov.eu Git - git/blob - 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_TWO
  70 };
  71
  72 struct rename_df_conflict_info {
  73         enum rename_type rename_type;
  74         struct diff_filepair *pair1;
  75         struct diff_filepair *pair2;
  76         const char *branch1;
  77         const char *branch2;
  78         struct stage_data *dst_entry1;
  79         struct stage_data *dst_entry2;
  80 };
  81
  82 /*
  83  * Since we want to write the index eventually, we cannot reuse the index
  84  * for these (temporary) data.
  85  */
  86 struct stage_data {
  87         struct {
  88                 unsigned mode;
  89                 unsigned char sha[20];
  90         } stages[4];
  91         struct rename_df_conflict_info *rename_df_conflict_info;
  92         unsigned processed:1;
  93 };
  94
  95 static inline void setup_rename_df_conflict_info(enum rename_type rename_type,
  96                                                  struct diff_filepair *pair1,
  97                                                  struct diff_filepair *pair2,
  98                                                  const char *branch1,
  99                                                  const char *branch2,
 100                                                  struct stage_data *dst_entry1,
 101                                                  struct stage_data *dst_entry2)
 102 {
 103         struct rename_df_conflict_info *ci = xcalloc(1, sizeof(struct rename_df_conflict_info));
 104         ci->rename_type = rename_type;
 105         ci->pair1 = pair1;
 106         ci->branch1 = branch1;
 107         ci->branch2 = branch2;
 108
 109         ci->dst_entry1 = dst_entry1;
 110         dst_entry1->rename_df_conflict_info = ci;
 111         dst_entry1->processed = 0;
 112
 113         assert(!pair2 == !dst_entry2);
 114         if (dst_entry2) {
 115                 ci->dst_entry2 = dst_entry2;
 116                 ci->pair2 = pair2;
 117                 dst_entry2->rename_df_conflict_info = ci;
 118                 dst_entry2->processed = 0;
 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
 368          * be removed to make room for the corresponding directory if
 369          * needed.  The files underneath the directories of such D/F
 370          * conflicts will be handled in process_entry(), while the
 371          * files of such D/F conflicts will be processed later in
 372          * process_df_entry().  If the corresponding directory ends up
 373          * being removed by the merge, then no additional work needs
 374          * to be done by process_df_entry() for the conflicting file.
 375          * If the directory needs to be written to the working copy,
 376          * then the conflicting file will simply be removed (e.g. in
 377          * make_room_for_path).  If the directory is written to the
 378          * working copy but the file also has a conflict that needs to
 379          * be resolved, then process_df_entry() will reinstate the
 380          * file with a new unique name.
 381          */
 382         const char *last_file = NULL;
 383         int last_len = 0;
 384         int i;
 385
 386         /*
 387          * If we're merging merge-bases, we don't want to bother with
 388          * any working directory changes.
 389          */
 390         if (o->call_depth)
 391                 return;
 392
 393         /* Ensure D/F conflicts are adjacent in the entries list. */
 394         qsort(entries->items, entries->nr, sizeof(*entries->items),
 395               string_list_df_name_compare);
 396
 397         string_list_clear(&o->df_conflict_file_set, 1);
 398         for (i = 0; i < entries->nr; i++) {
 399                 const char *path = entries->items[i].string;
 400                 int len = strlen(path);
 401                 struct stage_data *e = entries->items[i].util;
 402
 403                 /*
 404                  * Check if last_file & path correspond to a D/F conflict;
 405                  * i.e. whether path is last_file+'/'+<something>.
 406                  * If so, record that it's okay to remove last_file to make
 407                  * room for path and friends if needed.
 408                  */
 409                 if (last_file &&
 410                     len > last_len &&
 411                     memcmp(path, last_file, last_len) == 0 &&
 412                     path[last_len] == '/') {
 413                         output(o, 3, "Removing %s to make room for subdirectory; may re-add later.", last_file);
 414                         string_list_insert(&o->df_conflict_file_set, last_file);
 415                 }
 416
 417                 /*
 418                  * Determine whether path could exist as a file in the
 419                  * working directory as a possible D/F conflict.  This
 420                  * will only occur when it exists in stage 2 as a
 421                  * file.
 422                  */
 423                 if (S_ISREG(e->stages[2].mode) || S_ISLNK(e->stages[2].mode)) {
 424                         last_file = path;
 425                         last_len = len;
 426                 } else {
 427                         last_file = NULL;
 428                 }
 429         }
 430 }
 431
 432 struct rename {
 433         struct diff_filepair *pair;
 434         struct stage_data *src_entry;
 435         struct stage_data *dst_entry;
 436         unsigned processed:1;
 437 };
 438
 439 /*
 440  * Get information of all renames which occurred between 'o_tree' and
 441  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 442  * 'b_tree') to be able to associate the correct cache entries with
 443  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 444  */
 445 static struct string_list *get_renames(struct merge_options *o,
 446                                        struct tree *tree,
 447                                        struct tree *o_tree,
 448                                        struct tree *a_tree,
 449                                        struct tree *b_tree,
 450                                        struct string_list *entries)
 451 {
 452         int i;
 453         struct string_list *renames;
 454         struct diff_options opts;
 455
 456         renames = xcalloc(1, sizeof(struct string_list));
 457         diff_setup(&opts);
 458         DIFF_OPT_SET(&opts, RECURSIVE);
 459         opts.detect_rename = DIFF_DETECT_RENAME;
 460         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 461                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 462                             1000;
 463         opts.rename_score = o->rename_score;
 464         opts.show_rename_progress = o->show_rename_progress;
 465         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 466         if (diff_setup_done(&opts) < 0)
 467                 die("diff setup failed");
 468         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 469         diffcore_std(&opts);
 470         if (opts.needed_rename_limit > o->needed_rename_limit)
 471                 o->needed_rename_limit = opts.needed_rename_limit;
 472         for (i = 0; i < diff_queued_diff.nr; ++i) {
 473                 struct string_list_item *item;
 474                 struct rename *re;
 475                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 476                 if (pair->status != 'R') {
 477                         diff_free_filepair(pair);
 478                         continue;
 479                 }
 480                 re = xmalloc(sizeof(*re));
 481                 re->processed = 0;
 482                 re->pair = pair;
 483                 item = string_list_lookup(entries, re->pair->one->path);
 484                 if (!item)
 485                         re->src_entry = insert_stage_data(re->pair->one->path,
 486                                         o_tree, a_tree, b_tree, entries);
 487                 else
 488                         re->src_entry = item->util;
 489
 490                 item = string_list_lookup(entries, re->pair->two->path);
 491                 if (!item)
 492                         re->dst_entry = insert_stage_data(re->pair->two->path,
 493                                         o_tree, a_tree, b_tree, entries);
 494                 else
 495                         re->dst_entry = item->util;
 496                 item = string_list_insert(renames, pair->one->path);
 497                 item->util = re;
 498         }
 499         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 500         diff_queued_diff.nr = 0;
 501         diff_flush(&opts);
 502         return renames;
 503 }
 504
 505 static int update_stages(const char *path, const struct diff_filespec *o,
 506                          const struct diff_filespec *a,
 507                          const struct diff_filespec *b)
 508 {
 509         int clear = 1;
 510         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_SKIP_DFCHECK;
 511         if (clear)
 512                 if (remove_file_from_cache(path))
 513                         return -1;
 514         if (o)
 515                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 516                         return -1;
 517         if (a)
 518                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 519                         return -1;
 520         if (b)
 521                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 522                         return -1;
 523         return 0;
 524 }
 525
 526 static int update_stages_and_entry(const char *path,
 527                                    struct stage_data *entry,
 528                                    struct diff_filespec *o,
 529                                    struct diff_filespec *a,
 530                                    struct diff_filespec *b,
 531                                    int clear)
 532 {
 533         int options;
 534
 535         entry->processed = 0;
 536         entry->stages[1].mode = o->mode;
 537         entry->stages[2].mode = a->mode;
 538         entry->stages[3].mode = b->mode;
 539         hashcpy(entry->stages[1].sha, o->sha1);
 540         hashcpy(entry->stages[2].sha, a->sha1);
 541         hashcpy(entry->stages[3].sha, b->sha1);
 542         return update_stages(path, o, a, b);
 543 }
 544
 545 static int remove_file(struct merge_options *o, int clean,
 546                        const char *path, int no_wd)
 547 {
 548         int update_cache = o->call_depth || clean;
 549         int update_working_directory = !o->call_depth && !no_wd;
 550
 551         if (update_cache) {
 552                 if (remove_file_from_cache(path))
 553                         return -1;
 554         }
 555         if (update_working_directory) {
 556                 if (remove_path(path))
 557                         return -1;
 558         }
 559         return 0;
 560 }
 561
 562 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
 563 {
 564         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 565         int suffix = 0;
 566         struct stat st;
 567         char *p = newpath + strlen(path);
 568         strcpy(newpath, path);
 569         *(p++) = '~';
 570         strcpy(p, branch);
 571         for (; *p; ++p)
 572                 if ('/' == *p)
 573                         *p = '_';
 574         while (string_list_has_string(&o->current_file_set, newpath) ||
 575                string_list_has_string(&o->current_directory_set, newpath) ||
 576                lstat(newpath, &st) == 0)
 577                 sprintf(p, "_%d", suffix++);
 578
 579         string_list_insert(&o->current_file_set, newpath);
 580         return newpath;
 581 }
 582
 583 static void flush_buffer(int fd, const char *buf, unsigned long size)
 584 {
 585         while (size > 0) {
 586                 long ret = write_in_full(fd, buf, size);
 587                 if (ret < 0) {
 588                         /* Ignore epipe */
 589                         if (errno == EPIPE)
 590                                 break;
 591                         die_errno("merge-recursive");
 592                 } else if (!ret) {
 593                         die("merge-recursive: disk full?");
 594                 }
 595                 size -= ret;
 596                 buf += ret;
 597         }
 598 }
 599
 600 static int dir_in_way(const char *path, int check_working_copy)
 601 {
 602         int pos, pathlen = strlen(path);
 603         char *dirpath = xmalloc(pathlen + 2);
 604         struct stat st;
 605
 606         strcpy(dirpath, path);
 607         dirpath[pathlen] = '/';
 608         dirpath[pathlen+1] = '\0';
 609
 610         pos = cache_name_pos(dirpath, pathlen+1);
 611
 612         if (pos < 0)
 613                 pos = -1 - pos;
 614         if (pos < active_nr &&
 615             !strncmp(dirpath, active_cache[pos]->name, pathlen+1)) {
 616                 free(dirpath);
 617                 return 1;
 618         }
 619
 620         free(dirpath);
 621         return check_working_copy && !lstat(path, &st) && S_ISDIR(st.st_mode);
 622 }
 623
 624 static int would_lose_untracked(const char *path)
 625 {
 626         int pos = cache_name_pos(path, strlen(path));
 627
 628         if (pos < 0)
 629                 pos = -1 - pos;
 630         while (pos < active_nr &&
 631                !strcmp(path, active_cache[pos]->name)) {
 632                 /*
 633                  * If stage #0, it is definitely tracked.
 634                  * If it has stage #2 then it was tracked
 635                  * before this merge started.  All other
 636                  * cases the path was not tracked.
 637                  */
 638                 switch (ce_stage(active_cache[pos])) {
 639                 case 0:
 640                 case 2:
 641                         return 0;
 642                 }
 643                 pos++;
 644         }
 645         return file_exists(path);
 646 }
 647
 648 static int make_room_for_path(const char *path)
 649 {
 650         int status;
 651         const char *msg = "failed to create path '%s'%s";
 652
 653         status = safe_create_leading_directories_const(path);
 654         if (status) {
 655                 if (status == -3) {
 656                         /* something else exists */
 657                         error(msg, path, ": perhaps a D/F conflict?");
 658                         return -1;
 659                 }
 660                 die(msg, path, "");
 661         }
 662
 663         /*
 664          * Do not unlink a file in the work tree if we are not
 665          * tracking it.
 666          */
 667         if (would_lose_untracked(path))
 668                 return error("refusing to lose untracked file at '%s'",
 669                              path);
 670
 671         /* Successful unlink is good.. */
 672         if (!unlink(path))
 673                 return 0;
 674         /* .. and so is no existing file */
 675         if (errno == ENOENT)
 676                 return 0;
 677         /* .. but not some other error (who really cares what?) */
 678         return error(msg, path, ": perhaps a D/F conflict?");
 679 }
 680
 681 static void update_file_flags(struct merge_options *o,
 682                               const unsigned char *sha,
 683                               unsigned mode,
 684                               const char *path,
 685                               int update_cache,
 686                               int update_wd)
 687 {
 688         if (o->call_depth)
 689                 update_wd = 0;
 690
 691         if (update_wd) {
 692                 enum object_type type;
 693                 void *buf;
 694                 unsigned long size;
 695
 696                 if (S_ISGITLINK(mode)) {
 697                         /*
 698                          * We may later decide to recursively descend into
 699                          * the submodule directory and update its index
 700                          * and/or work tree, but we do not do that now.
 701                          */
 702                         update_wd = 0;
 703                         goto update_index;
 704                 }
 705
 706                 buf = read_sha1_file(sha, &type, &size);
 707                 if (!buf)
 708                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 709                 if (type != OBJ_BLOB)
 710                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 711                 if (S_ISREG(mode)) {
 712                         struct strbuf strbuf = STRBUF_INIT;
 713                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
 714                                 free(buf);
 715                                 size = strbuf.len;
 716                                 buf = strbuf_detach(&strbuf, NULL);
 717                         }
 718                 }
 719
 720                 if (make_room_for_path(path) < 0) {
 721                         update_wd = 0;
 722                         free(buf);
 723                         goto update_index;
 724                 }
 725                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 726                         int fd;
 727                         if (mode & 0100)
 728                                 mode = 0777;
 729                         else
 730                                 mode = 0666;
 731                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 732                         if (fd < 0)
 733                                 die_errno("failed to open '%s'", path);
 734                         flush_buffer(fd, buf, size);
 735                         close(fd);
 736                 } else if (S_ISLNK(mode)) {
 737                         char *lnk = xmemdupz(buf, size);
 738                         safe_create_leading_directories_const(path);
 739                         unlink(path);
 740                         if (symlink(lnk, path))
 741                                 die_errno("failed to symlink '%s'", path);
 742                         free(lnk);
 743                 } else
 744                         die("do not know what to do with %06o %s '%s'",
 745                             mode, sha1_to_hex(sha), path);
 746                 free(buf);
 747         }
 748  update_index:
 749         if (update_cache)
 750                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 751 }
 752
 753 static void update_file(struct merge_options *o,
 754                         int clean,
 755                         const unsigned char *sha,
 756                         unsigned mode,
 757                         const char *path)
 758 {
 759         update_file_flags(o, sha, mode, path, o->call_depth || clean, !o->call_depth);
 760 }
 761
 762 /* Low level file merging, update and removal */
 763
 764 struct merge_file_info {
 765         unsigned char sha[20];
 766         unsigned mode;
 767         unsigned clean:1,
 768                  merge:1;
 769 };
 770
 771 static int merge_3way(struct merge_options *o,
 772                       mmbuffer_t *result_buf,
 773                       const struct diff_filespec *one,
 774                       const struct diff_filespec *a,
 775                       const struct diff_filespec *b,
 776                       const char *branch1,
 777                       const char *branch2)
 778 {
 779         mmfile_t orig, src1, src2;
 780         struct ll_merge_options ll_opts = {0};
 781         char *base_name, *name1, *name2;
 782         int merge_status;
 783
 784         ll_opts.renormalize = o->renormalize;
 785         ll_opts.xdl_opts = o->xdl_opts;
 786
 787         if (o->call_depth) {
 788                 ll_opts.virtual_ancestor = 1;
 789                 ll_opts.variant = 0;
 790         } else {
 791                 switch (o->recursive_variant) {
 792                 case MERGE_RECURSIVE_OURS:
 793                         ll_opts.variant = XDL_MERGE_FAVOR_OURS;
 794                         break;
 795                 case MERGE_RECURSIVE_THEIRS:
 796                         ll_opts.variant = XDL_MERGE_FAVOR_THEIRS;
 797                         break;
 798                 default:
 799                         ll_opts.variant = 0;
 800                         break;
 801                 }
 802         }
 803
 804         if (strcmp(a->path, b->path) ||
 805             (o->ancestor != NULL && strcmp(a->path, one->path) != 0)) {
 806                 base_name = o->ancestor == NULL ? NULL :
 807                         xstrdup(mkpath("%s:%s", o->ancestor, one->path));
 808                 name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 809                 name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 810         } else {
 811                 base_name = o->ancestor == NULL ? NULL :
 812                         xstrdup(mkpath("%s", o->ancestor));
 813                 name1 = xstrdup(mkpath("%s", branch1));
 814                 name2 = xstrdup(mkpath("%s", branch2));
 815         }
 816
 817         read_mmblob(&orig, one->sha1);
 818         read_mmblob(&src1, a->sha1);
 819         read_mmblob(&src2, b->sha1);
 820
 821         merge_status = ll_merge(result_buf, a->path, &orig, base_name,
 822                                 &src1, name1, &src2, name2, &ll_opts);
 823
 824         free(name1);
 825         free(name2);
 826         free(orig.ptr);
 827         free(src1.ptr);
 828         free(src2.ptr);
 829         return merge_status;
 830 }
 831
 832 static struct merge_file_info merge_file(struct merge_options *o,
 833                                          const struct diff_filespec *one,
 834                                          const struct diff_filespec *a,
 835                                          const struct diff_filespec *b,
 836                                          const char *branch1,
 837                                          const char *branch2)
 838 {
 839         struct merge_file_info result;
 840         result.merge = 0;
 841         result.clean = 1;
 842
 843         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 844                 result.clean = 0;
 845                 if (S_ISREG(a->mode)) {
 846                         result.mode = a->mode;
 847                         hashcpy(result.sha, a->sha1);
 848                 } else {
 849                         result.mode = b->mode;
 850                         hashcpy(result.sha, b->sha1);
 851                 }
 852         } else {
 853                 if (!sha_eq(a->sha1, one->sha1) && !sha_eq(b->sha1, one->sha1))
 854                         result.merge = 1;
 855
 856                 /*
 857                  * Merge modes
 858                  */
 859                 if (a->mode == b->mode || a->mode == one->mode)
 860                         result.mode = b->mode;
 861                 else {
 862                         result.mode = a->mode;
 863                         if (b->mode != one->mode) {
 864                                 result.clean = 0;
 865                                 result.merge = 1;
 866                         }
 867                 }
 868
 869                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, one->sha1))
 870                         hashcpy(result.sha, b->sha1);
 871                 else if (sha_eq(b->sha1, one->sha1))
 872                         hashcpy(result.sha, a->sha1);
 873                 else if (S_ISREG(a->mode)) {
 874                         mmbuffer_t result_buf;
 875                         int merge_status;
 876
 877                         merge_status = merge_3way(o, &result_buf, one, a, b,
 878                                                   branch1, branch2);
 879
 880                         if ((merge_status < 0) || !result_buf.ptr)
 881                                 die("Failed to execute internal merge");
 882
 883                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 884                                             blob_type, result.sha))
 885                                 die("Unable to add %s to database",
 886                                     a->path);
 887
 888                         free(result_buf.ptr);
 889                         result.clean = (merge_status == 0);
 890                 } else if (S_ISGITLINK(a->mode)) {
 891                         result.clean = merge_submodule(result.sha, one->path, one->sha1,
 892                                                        a->sha1, b->sha1);
 893                 } else if (S_ISLNK(a->mode)) {
 894                         hashcpy(result.sha, a->sha1);
 895
 896                         if (!sha_eq(a->sha1, b->sha1))
 897                                 result.clean = 0;
 898                 } else {
 899                         die("unsupported object type in the tree");
 900                 }
 901         }
 902
 903         return result;
 904 }
 905
 906 static void conflict_rename_delete(struct merge_options *o,
 907                                    struct diff_filepair *pair,
 908                                    const char *rename_branch,
 909                                    const char *other_branch)
 910 {
 911         char *dest_name = pair->two->path;
 912         int df_conflict = 0;
 913
 914         output(o, 1, "CONFLICT (rename/delete): Rename %s->%s in %s "
 915                "and deleted in %s",
 916                pair->one->path, pair->two->path, rename_branch,
 917                other_branch);
 918         if (!o->call_depth)
 919                 update_stages(dest_name, NULL,
 920                               rename_branch == o->branch1 ? pair->two : NULL,
 921                               rename_branch == o->branch1 ? NULL : pair->two);
 922         if (dir_in_way(dest_name, !o->call_depth)) {
 923                 dest_name = unique_path(o, dest_name, rename_branch);
 924                 df_conflict = 1;
 925         }
 926         update_file(o, 0, pair->two->sha1, pair->two->mode, dest_name);
 927         if (df_conflict)
 928                 free(dest_name);
 929 }
 930
 931 static void conflict_rename_rename_1to2(struct merge_options *o,
 932                                         struct diff_filepair *pair1,
 933                                         const char *branch1,
 934                                         struct diff_filepair *pair2,
 935                                         const char *branch2)
 936 {
 937         /* One file was renamed in both branches, but to different names. */
 938         char *del[2];
 939         int delp = 0;
 940         const char *ren1_dst = pair1->two->path;
 941         const char *ren2_dst = pair2->two->path;
 942         const char *dst_name1 = ren1_dst;
 943         const char *dst_name2 = ren2_dst;
 944         if (dir_in_way(ren1_dst, !o->call_depth)) {
 945                 dst_name1 = del[delp++] = unique_path(o, ren1_dst, branch1);
 946                 output(o, 1, "%s is a directory in %s adding as %s instead",
 947                        ren1_dst, branch2, dst_name1);
 948         }
 949         if (dir_in_way(ren2_dst, !o->call_depth)) {
 950                 dst_name2 = del[delp++] = unique_path(o, ren2_dst, branch2);
 951                 output(o, 1, "%s is a directory in %s adding as %s instead",
 952                        ren2_dst, branch1, dst_name2);
 953         }
 954         if (o->call_depth) {
 955                 remove_file_from_cache(dst_name1);
 956                 remove_file_from_cache(dst_name2);
 957                 /*
 958                  * Uncomment to leave the conflicting names in the resulting tree
 959                  *
 960                  * update_file(o, 0, pair1->two->sha1, pair1->two->mode, dst_name1);
 961                  * update_file(o, 0, pair2->two->sha1, pair2->two->mode, dst_name2);
 962                  */
 963         } else {
 964                 update_stages(ren1_dst, NULL, pair1->two, NULL);
 965                 update_stages(ren2_dst, NULL, NULL, pair2->two);
 966
 967                 update_file(o, 0, pair1->two->sha1, pair1->two->mode, dst_name1);
 968                 update_file(o, 0, pair2->two->sha1, pair2->two->mode, dst_name2);
 969         }
 970         while (delp--)
 971                 free(del[delp]);
 972 }
 973
 974 static void conflict_rename_rename_2to1(struct merge_options *o,
 975                                         struct rename *ren1,
 976                                         const char *branch1,
 977                                         struct rename *ren2,
 978                                         const char *branch2)
 979 {
 980         /* Two files were renamed to the same thing. */
 981         char *new_path1 = unique_path(o, ren1->pair->two->path, branch1);
 982         char *new_path2 = unique_path(o, ren2->pair->two->path, branch2);
 983         output(o, 1, "Renaming %s to %s and %s to %s instead",
 984                ren1->pair->one->path, new_path1,
 985                ren2->pair->one->path, new_path2);
 986         remove_file(o, 0, ren1->pair->two->path, 0);
 987         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 988         update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 989         free(new_path2);
 990         free(new_path1);
 991 }
 992
 993 static int process_renames(struct merge_options *o,
 994                            struct string_list *a_renames,
 995                            struct string_list *b_renames)
 996 {
 997         int clean_merge = 1, i, j;
 998         struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
 999         struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
1000         const struct rename *sre;
1001
1002         for (i = 0; i < a_renames->nr; i++) {
1003                 sre = a_renames->items[i].util;
1004                 string_list_insert(&a_by_dst, sre->pair->two->path)->util
1005                         = sre->dst_entry;
1006         }
1007         for (i = 0; i < b_renames->nr; i++) {
1008                 sre = b_renames->items[i].util;
1009                 string_list_insert(&b_by_dst, sre->pair->two->path)->util
1010                         = sre->dst_entry;
1011         }
1012
1013         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
1014                 struct string_list *renames1, *renames2Dst;
1015                 struct rename *ren1 = NULL, *ren2 = NULL;
1016                 const char *branch1, *branch2;
1017                 const char *ren1_src, *ren1_dst;
1018
1019                 if (i >= a_renames->nr) {
1020                         ren2 = b_renames->items[j++].util;
1021                 } else if (j >= b_renames->nr) {
1022                         ren1 = a_renames->items[i++].util;
1023                 } else {
1024                         int compare = strcmp(a_renames->items[i].string,
1025                                              b_renames->items[j].string);
1026                         if (compare <= 0)
1027                                 ren1 = a_renames->items[i++].util;
1028                         if (compare >= 0)
1029                                 ren2 = b_renames->items[j++].util;
1030                 }
1031
1032                 /* TODO: refactor, so that 1/2 are not needed */
1033                 if (ren1) {
1034                         renames1 = a_renames;
1035                         renames2Dst = &b_by_dst;
1036                         branch1 = o->branch1;
1037                         branch2 = o->branch2;
1038                 } else {
1039                         struct rename *tmp;
1040                         renames1 = b_renames;
1041                         renames2Dst = &a_by_dst;
1042                         branch1 = o->branch2;
1043                         branch2 = o->branch1;
1044                         tmp = ren2;
1045                         ren2 = ren1;
1046                         ren1 = tmp;
1047                 }
1048
1049                 ren1->dst_entry->processed = 1;
1050                 ren1->src_entry->processed = 1;
1051
1052                 if (ren1->processed)
1053                         continue;
1054                 ren1->processed = 1;
1055
1056                 ren1_src = ren1->pair->one->path;
1057                 ren1_dst = ren1->pair->two->path;
1058
1059                 if (ren2) {
1060                         const char *ren2_src = ren2->pair->one->path;
1061                         const char *ren2_dst = ren2->pair->two->path;
1062                         /* Renamed in 1 and renamed in 2 */
1063                         if (strcmp(ren1_src, ren2_src) != 0)
1064                                 die("ren1.src != ren2.src");
1065                         ren2->dst_entry->processed = 1;
1066                         ren2->processed = 1;
1067                         if (strcmp(ren1_dst, ren2_dst) != 0) {
1068                                 setup_rename_df_conflict_info(RENAME_ONE_FILE_TO_TWO,
1069                                                               ren1->pair,
1070                                                               ren2->pair,
1071                                                               branch1,
1072                                                               branch2,
1073                                                               ren1->dst_entry,
1074                                                               ren2->dst_entry);
1075                         } else {
1076                                 remove_file(o, 1, ren1_src, 1);
1077                                 update_stages_and_entry(ren1_dst,
1078                                                         ren1->dst_entry,
1079                                                         ren1->pair->one,
1080                                                         ren1->pair->two,
1081                                                         ren2->pair->two,
1082                                                         1 /* clear */);
1083                         }
1084                 } else {
1085                         /* Renamed in 1, maybe changed in 2 */
1086                         struct string_list_item *item;
1087                         /* we only use sha1 and mode of these */
1088                         struct diff_filespec src_other, dst_other;
1089                         int try_merge;
1090
1091                         /*
1092                          * unpack_trees loads entries from common-commit
1093                          * into stage 1, from head-commit into stage 2, and
1094                          * from merge-commit into stage 3.  We keep track
1095                          * of which side corresponds to the rename.
1096                          */
1097                         int renamed_stage = a_renames == renames1 ? 2 : 3;
1098                         int other_stage =   a_renames == renames1 ? 3 : 2;
1099
1100                         remove_file(o, 1, ren1_src, o->call_depth || renamed_stage == 2);
1101
1102                         hashcpy(src_other.sha1, ren1->src_entry->stages[other_stage].sha);
1103                         src_other.mode = ren1->src_entry->stages[other_stage].mode;
1104                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[other_stage].sha);
1105                         dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
1106                         try_merge = 0;
1107
1108                         if (sha_eq(src_other.sha1, null_sha1)) {
1109                                 if (dir_in_way(ren1_dst, 0 /*check_wc*/)) {
1110                                         ren1->dst_entry->processed = 0;
1111                                         setup_rename_df_conflict_info(RENAME_DELETE,
1112                                                                       ren1->pair,
1113                                                                       NULL,
1114                                                                       branch1,
1115                                                                       branch2,
1116                                                                       ren1->dst_entry,
1117                                                                       NULL);
1118                                 } else {
1119                                         clean_merge = 0;
1120                                         conflict_rename_delete(o, ren1->pair, branch1, branch2);
1121                                 }
1122                         } else if ((dst_other.mode == ren1->pair->two->mode) &&
1123                                    sha_eq(dst_other.sha1, ren1->pair->two->sha1)) {
1124                                 /* Added file on the other side
1125                                    identical to the file being
1126                                    renamed: clean merge */
1127                                 update_file(o, 1, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
1128                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
1129                                 clean_merge = 0;
1130                                 try_merge = 1;
1131                                 output(o, 1, "CONFLICT (rename/add): Rename %s->%s in %s. "
1132                                        "%s added in %s",
1133                                        ren1_src, ren1_dst, branch1,
1134                                        ren1_dst, branch2);
1135                                 if (o->call_depth) {
1136                                         struct merge_file_info mfi;
1137                                         struct diff_filespec one, a, b;
1138
1139                                         one.path = a.path = b.path =
1140                                                 (char *)ren1_dst;
1141                                         hashcpy(one.sha1, null_sha1);
1142                                         one.mode = 0;
1143                                         hashcpy(a.sha1, ren1->pair->two->sha1);
1144                                         a.mode = ren1->pair->two->mode;
1145                                         hashcpy(b.sha1, dst_other.sha1);
1146                                         b.mode = dst_other.mode;
1147                                         mfi = merge_file(o, &one, &a, &b,
1148                                                          branch1,
1149                                                          branch2);
1150                                         output(o, 1, "Adding merged %s", ren1_dst);
1151                                         update_file(o, 0,
1152                                                     mfi.sha,
1153                                                     mfi.mode,
1154                                                     ren1_dst);
1155                                         try_merge = 0;
1156                                 } else {
1157                                         char *new_path = unique_path(o, ren1_dst, branch2);
1158                                         output(o, 1, "Adding as %s instead", new_path);
1159                                         update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
1160                                         free(new_path);
1161                                 }
1162                         } else if ((item = string_list_lookup(renames2Dst, ren1_dst))) {
1163                                 ren2 = item->util;
1164                                 clean_merge = 0;
1165                                 ren2->processed = 1;
1166                                 output(o, 1, "CONFLICT (rename/rename): "
1167                                        "Rename %s->%s in %s. "
1168                                        "Rename %s->%s in %s",
1169                                        ren1_src, ren1_dst, branch1,
1170                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
1171                                 conflict_rename_rename_2to1(o, ren1, branch1, ren2, branch2);
1172                         } else
1173                                 try_merge = 1;
1174
1175                         if (try_merge) {
1176                                 struct diff_filespec *one, *a, *b;
1177                                 src_other.path = (char *)ren1_src;
1178
1179                                 one = ren1->pair->one;
1180                                 if (a_renames == renames1) {
1181                                         a = ren1->pair->two;
1182                                         b = &src_other;
1183                                 } else {
1184                                         b = ren1->pair->two;
1185                                         a = &src_other;
1186                                 }
1187                                 update_stages_and_entry(ren1_dst, ren1->dst_entry, one, a, b, 1);
1188                                 if (dir_in_way(ren1_dst, 0 /*check_wc*/)) {
1189                                         setup_rename_df_conflict_info(RENAME_NORMAL,
1190                                                                       ren1->pair,
1191                                                                       NULL,
1192                                                                       branch1,
1193                                                                       NULL,
1194                                                                       ren1->dst_entry,
1195                                                                       NULL);
1196                                 }
1197                         }
1198                 }
1199         }
1200         string_list_clear(&a_by_dst, 0);
1201         string_list_clear(&b_by_dst, 0);
1202
1203         return clean_merge;
1204 }
1205
1206 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1207 {
1208         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1209 }
1210
1211 static int read_sha1_strbuf(const unsigned char *sha1, struct strbuf *dst)
1212 {
1213         void *buf;
1214         enum object_type type;
1215         unsigned long size;
1216         buf = read_sha1_file(sha1, &type, &size);
1217         if (!buf)
1218                 return error("cannot read object %s", sha1_to_hex(sha1));
1219         if (type != OBJ_BLOB) {
1220                 free(buf);
1221                 return error("object %s is not a blob", sha1_to_hex(sha1));
1222         }
1223         strbuf_attach(dst, buf, size, size + 1);
1224         return 0;
1225 }
1226
1227 static int blob_unchanged(const unsigned char *o_sha,
1228                           const unsigned char *a_sha,
1229                           int renormalize, const char *path)
1230 {
1231         struct strbuf o = STRBUF_INIT;
1232         struct strbuf a = STRBUF_INIT;
1233         int ret = 0; /* assume changed for safety */
1234
1235         if (sha_eq(o_sha, a_sha))
1236                 return 1;
1237         if (!renormalize)
1238                 return 0;
1239
1240         assert(o_sha && a_sha);
1241         if (read_sha1_strbuf(o_sha, &o) || read_sha1_strbuf(a_sha, &a))
1242                 goto error_return;
1243         /*
1244          * Note: binary | is used so that both renormalizations are
1245          * performed.  Comparison can be skipped if both files are
1246          * unchanged since their sha1s have already been compared.
1247          */
1248         if (renormalize_buffer(path, o.buf, o.len, &o) |
1249             renormalize_buffer(path, a.buf, o.len, &a))
1250                 ret = (o.len == a.len && !memcmp(o.buf, a.buf, o.len));
1251
1252 error_return:
1253         strbuf_release(&o);
1254         strbuf_release(&a);
1255         return ret;
1256 }
1257
1258 static void handle_delete_modify(struct merge_options *o,
1259                                  const char *path,
1260                                  const char *new_path,
1261                                  unsigned char *a_sha, int a_mode,
1262                                  unsigned char *b_sha, int b_mode)
1263 {
1264         if (!a_sha) {
1265                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1266                        "and modified in %s. Version %s of %s left in tree%s%s.",
1267                        path, o->branch1,
1268                        o->branch2, o->branch2, path,
1269                        path == new_path ? "" : " at ",
1270                        path == new_path ? "" : new_path);
1271                 update_file(o, 0, b_sha, b_mode, new_path);
1272         } else {
1273                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1274                        "and modified in %s. Version %s of %s left in tree%s%s.",
1275                        path, o->branch2,
1276                        o->branch1, o->branch1, path,
1277                        path == new_path ? "" : " at ",
1278                        path == new_path ? "" : new_path);
1279                 update_file(o, 0, a_sha, a_mode, new_path);
1280         }
1281 }
1282
1283 static int merge_content(struct merge_options *o,
1284                          const char *path,
1285                          unsigned char *o_sha, int o_mode,
1286                          unsigned char *a_sha, int a_mode,
1287                          unsigned char *b_sha, int b_mode,
1288                          const char *df_rename_conflict_branch)
1289 {
1290         const char *reason = "content";
1291         struct merge_file_info mfi;
1292         struct diff_filespec one, a, b;
1293         unsigned df_conflict_remains = 0;
1294
1295         if (!o_sha) {
1296                 reason = "add/add";
1297                 o_sha = (unsigned char *)null_sha1;
1298         }
1299         one.path = a.path = b.path = (char *)path;
1300         hashcpy(one.sha1, o_sha);
1301         one.mode = o_mode;
1302         hashcpy(a.sha1, a_sha);
1303         a.mode = a_mode;
1304         hashcpy(b.sha1, b_sha);
1305         b.mode = b_mode;
1306
1307         mfi = merge_file(o, &one, &a, &b, o->branch1, o->branch2);
1308         if (df_rename_conflict_branch &&
1309             dir_in_way(path, !o->call_depth)) {
1310                 df_conflict_remains = 1;
1311         }
1312
1313         if (mfi.clean && !df_conflict_remains &&
1314             sha_eq(mfi.sha, a_sha) && mfi.mode == a.mode)
1315                 output(o, 3, "Skipped %s (merged same as existing)", path);
1316         else
1317                 output(o, 2, "Auto-merging %s", path);
1318
1319         if (!mfi.clean) {
1320                 if (S_ISGITLINK(mfi.mode))
1321                         reason = "submodule";
1322                 output(o, 1, "CONFLICT (%s): Merge conflict in %s",
1323                                 reason, path);
1324         }
1325
1326         if (df_conflict_remains) {
1327                 char *new_path;
1328                 update_file_flags(o, mfi.sha, mfi.mode, path,
1329                                   o->call_depth || mfi.clean, 0);
1330                 new_path = unique_path(o, path, df_rename_conflict_branch);
1331                 mfi.clean = 0;
1332                 output(o, 1, "Adding as %s instead", new_path);
1333                 update_file_flags(o, mfi.sha, mfi.mode, new_path, 0, 1);
1334                 free(new_path);
1335         } else {
1336                 update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
1337         }
1338         return mfi.clean;
1339
1340 }
1341
1342 /* Per entry merge function */
1343 static int process_entry(struct merge_options *o,
1344                          const char *path, struct stage_data *entry)
1345 {
1346         /*
1347         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1348         print_index_entry("\tpath: ", entry);
1349         */
1350         int clean_merge = 1;
1351         int normalize = o->renormalize;
1352         unsigned o_mode = entry->stages[1].mode;
1353         unsigned a_mode = entry->stages[2].mode;
1354         unsigned b_mode = entry->stages[3].mode;
1355         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1356         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1357         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1358
1359         if (entry->rename_df_conflict_info)
1360                 return 1; /* Such cases are handled elsewhere. */
1361
1362         entry->processed = 1;
1363         if (o_sha && (!a_sha || !b_sha)) {
1364                 /* Case A: Deleted in one */
1365                 if ((!a_sha && !b_sha) ||
1366                     (!b_sha && blob_unchanged(o_sha, a_sha, normalize, path)) ||
1367                     (!a_sha && blob_unchanged(o_sha, b_sha, normalize, path))) {
1368                         /* Deleted in both or deleted in one and
1369                          * unchanged in the other */
1370                         if (a_sha)
1371                                 output(o, 2, "Removing %s", path);
1372                         /* do not touch working file if it did not exist */
1373                         remove_file(o, 1, path, !a_sha);
1374                 } else if (dir_in_way(path, 0 /*check_wc*/)) {
1375                         entry->processed = 0;
1376                         return 1; /* Assume clean until processed */
1377                 } else {
1378                         /* Deleted in one and changed in the other */
1379                         clean_merge = 0;
1380                         handle_delete_modify(o, path, path,
1381                                              a_sha, a_mode, b_sha, b_mode);
1382                 }
1383
1384         } else if ((!o_sha && a_sha && !b_sha) ||
1385                    (!o_sha && !a_sha && b_sha)) {
1386                 /* Case B: Added in one. */
1387                 unsigned mode;
1388                 const unsigned char *sha;
1389
1390                 if (a_sha) {
1391                         mode = a_mode;
1392                         sha = a_sha;
1393                 } else {
1394                         mode = b_mode;
1395                         sha = b_sha;
1396                 }
1397                 if (dir_in_way(path, 0 /*check_wc*/)) {
1398                         /* Handle D->F conflicts after all subfiles */
1399                         entry->processed = 0;
1400                         return 1; /* Assume clean until processed */
1401                 } else {
1402                         output(o, 2, "Adding %s", path);
1403                         update_file(o, 1, sha, mode, path);
1404                 }
1405         } else if (a_sha && b_sha) {
1406                 /* Case C: Added in both (check for same permissions) and */
1407                 /* case D: Modified in both, but differently. */
1408                 clean_merge = merge_content(o, path,
1409                                             o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
1410                                             NULL);
1411         } else if (!o_sha && !a_sha && !b_sha) {
1412                 /*
1413                  * this entry was deleted altogether. a_mode == 0 means
1414                  * we had that path and want to actively remove it.
1415                  */
1416                 remove_file(o, 1, path, !a_mode);
1417         } else
1418                 die("Fatal merge failure, shouldn't happen.");
1419
1420         return clean_merge;
1421 }
1422
1423 /*
1424  * Per entry merge function for D/F (and/or rename) conflicts.  In the
1425  * cases we can cleanly resolve D/F conflicts, process_entry() can
1426  * clean out all the files below the directory for us.  All D/F
1427  * conflict cases must be handled here at the end to make sure any
1428  * directories that can be cleaned out, are.
1429  *
1430  * Some rename conflicts may also be handled here that don't necessarily
1431  * involve D/F conflicts, since the code to handle them is generic enough
1432  * to handle those rename conflicts with or without D/F conflicts also
1433  * being involved.
1434  */
1435 static int process_df_entry(struct merge_options *o,
1436                             const char *path, struct stage_data *entry)
1437 {
1438         int clean_merge = 1;
1439         unsigned o_mode = entry->stages[1].mode;
1440         unsigned a_mode = entry->stages[2].mode;
1441         unsigned b_mode = entry->stages[3].mode;
1442         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1443         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1444         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1445
1446         entry->processed = 1;
1447         if (entry->rename_df_conflict_info) {
1448                 struct rename_df_conflict_info *conflict_info = entry->rename_df_conflict_info;
1449                 char *src;
1450                 switch (conflict_info->rename_type) {
1451                 case RENAME_NORMAL:
1452                         clean_merge = merge_content(o, path,
1453                                                     o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
1454                                                     conflict_info->branch1);
1455                         break;
1456                 case RENAME_DELETE:
1457                         clean_merge = 0;
1458                         conflict_rename_delete(o, conflict_info->pair1,
1459                                                conflict_info->branch1,
1460                                                conflict_info->branch2);
1461                         break;
1462                 case RENAME_ONE_FILE_TO_TWO:
1463                         src = conflict_info->pair1->one->path;
1464                         clean_merge = 0;
1465                         output(o, 1, "CONFLICT (rename/rename): "
1466                                "Rename \"%s\"->\"%s\" in branch \"%s\" "
1467                                "rename \"%s\"->\"%s\" in \"%s\"%s",
1468                                src, conflict_info->pair1->two->path, conflict_info->branch1,
1469                                src, conflict_info->pair2->two->path, conflict_info->branch2,
1470                                o->call_depth ? " (left unresolved)" : "");
1471                         if (o->call_depth) {
1472                                 remove_file_from_cache(src);
1473                                 update_file(o, 0, conflict_info->pair1->one->sha1,
1474                                             conflict_info->pair1->one->mode, src);
1475                         }
1476                         conflict_rename_rename_1to2(o, conflict_info->pair1,
1477                                                     conflict_info->branch1,
1478                                                     conflict_info->pair2,
1479                                                     conflict_info->branch2);
1480                         conflict_info->dst_entry2->processed = 1;
1481                         break;
1482                 default:
1483                         entry->processed = 0;
1484                         break;
1485                 }
1486         } else if (o_sha && (!a_sha || !b_sha)) {
1487                 /* Modify/delete; deleted side may have put a directory in the way */
1488                 char *renamed = NULL;
1489                 if (dir_in_way(path, !o->call_depth)) {
1490                         renamed = unique_path(o, path, a_sha ? o->branch1 : o->branch2);
1491                 }
1492                 clean_merge = 0;
1493                 handle_delete_modify(o, path, renamed ? renamed : path,
1494                                      a_sha, a_mode, b_sha, b_mode);
1495                 free(renamed);
1496         } else if (!o_sha && !!a_sha != !!b_sha) {
1497                 /* directory -> (directory, file) or <nothing> -> (directory, file) */
1498                 const char *add_branch;
1499                 const char *other_branch;
1500                 unsigned mode;
1501                 const unsigned char *sha;
1502                 const char *conf;
1503
1504                 if (a_sha) {
1505                         add_branch = o->branch1;
1506                         other_branch = o->branch2;
1507                         mode = a_mode;
1508                         sha = a_sha;
1509                         conf = "file/directory";
1510                 } else {
1511                         add_branch = o->branch2;
1512                         other_branch = o->branch1;
1513                         mode = b_mode;
1514                         sha = b_sha;
1515                         conf = "directory/file";
1516                 }
1517                 if (dir_in_way(path, !o->call_depth)) {
1518                         char *new_path = unique_path(o, path, add_branch);
1519                         clean_merge = 0;
1520                         output(o, 1, "CONFLICT (%s): There is a directory with name %s in %s. "
1521                                "Adding %s as %s",
1522                                conf, path, other_branch, path, new_path);
1523                         update_file(o, 0, sha, mode, new_path);
1524                         if (o->call_depth)
1525                                 remove_file_from_cache(path);
1526                         free(new_path);
1527                 } else {
1528                         output(o, 2, "Adding %s", path);
1529                         update_file(o, 1, sha, mode, path);
1530                 }
1531         } else {
1532                 entry->processed = 0;
1533                 return 1; /* not handled; assume clean until processed */
1534         }
1535
1536         return clean_merge;
1537 }
1538
1539 int merge_trees(struct merge_options *o,
1540                 struct tree *head,
1541                 struct tree *merge,
1542                 struct tree *common,
1543                 struct tree **result)
1544 {
1545         int code, clean;
1546
1547         if (o->subtree_shift) {
1548                 merge = shift_tree_object(head, merge, o->subtree_shift);
1549                 common = shift_tree_object(head, common, o->subtree_shift);
1550         }
1551
1552         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1553                 output(o, 0, "Already up-to-date!");
1554                 *result = head;
1555                 return 1;
1556         }
1557
1558         code = git_merge_trees(o->call_depth, common, head, merge);
1559
1560         if (code != 0) {
1561                 if (show(o, 4) || o->call_depth)
1562                         die("merging of trees %s and %s failed",
1563                             sha1_to_hex(head->object.sha1),
1564                             sha1_to_hex(merge->object.sha1));
1565                 else
1566                         exit(128);
1567         }
1568
1569         if (unmerged_cache()) {
1570                 struct string_list *entries, *re_head, *re_merge;
1571                 int i;
1572                 string_list_clear(&o->current_file_set, 1);
1573                 string_list_clear(&o->current_directory_set, 1);
1574                 get_files_dirs(o, head);
1575                 get_files_dirs(o, merge);
1576
1577                 entries = get_unmerged();
1578                 record_df_conflict_files(o, entries);
1579                 re_head  = get_renames(o, head, common, head, merge, entries);
1580                 re_merge = get_renames(o, merge, common, head, merge, entries);
1581                 clean = process_renames(o, re_head, re_merge);
1582                 for (i = 0; i < entries->nr; i++) {
1583                         const char *path = entries->items[i].string;
1584                         struct stage_data *e = entries->items[i].util;
1585                         if (!e->processed
1586                                 && !process_entry(o, path, e))
1587                                 clean = 0;
1588                 }
1589                 for (i = 0; i < entries->nr; i++) {
1590                         const char *path = entries->items[i].string;
1591                         struct stage_data *e = entries->items[i].util;
1592                         if (!e->processed
1593                                 && !process_df_entry(o, path, e))
1594                                 clean = 0;
1595                 }
1596                 for (i = 0; i < entries->nr; i++) {
1597                         struct stage_data *e = entries->items[i].util;
1598                         if (!e->processed)
1599                                 die("Unprocessed path??? %s",
1600                                     entries->items[i].string);
1601                 }
1602
1603                 string_list_clear(re_merge, 0);
1604                 string_list_clear(re_head, 0);
1605                 string_list_clear(entries, 1);
1606
1607         }
1608         else
1609                 clean = 1;
1610
1611         if (o->call_depth)
1612                 *result = write_tree_from_memory(o);
1613
1614         return clean;
1615 }
1616
1617 static struct commit_list *reverse_commit_list(struct commit_list *list)
1618 {
1619         struct commit_list *next = NULL, *current, *backup;
1620         for (current = list; current; current = backup) {
1621                 backup = current->next;
1622                 current->next = next;
1623                 next = current;
1624         }
1625         return next;
1626 }
1627
1628 /*
1629  * Merge the commits h1 and h2, return the resulting virtual
1630  * commit object and a flag indicating the cleanness of the merge.
1631  */
1632 int merge_recursive(struct merge_options *o,
1633                     struct commit *h1,
1634                     struct commit *h2,
1635                     struct commit_list *ca,
1636                     struct commit **result)
1637 {
1638         struct commit_list *iter;
1639         struct commit *merged_common_ancestors;
1640         struct tree *mrtree = mrtree;
1641         int clean;
1642
1643         if (show(o, 4)) {
1644                 output(o, 4, "Merging:");
1645                 output_commit_title(o, h1);
1646                 output_commit_title(o, h2);
1647         }
1648
1649         if (!ca) {
1650                 ca = get_merge_bases(h1, h2, 1);
1651                 ca = reverse_commit_list(ca);
1652         }
1653
1654         if (show(o, 5)) {
1655                 output(o, 5, "found %u common ancestor(s):", commit_list_count(ca));
1656                 for (iter = ca; iter; iter = iter->next)
1657                         output_commit_title(o, iter->item);
1658         }
1659
1660         merged_common_ancestors = pop_commit(&ca);
1661         if (merged_common_ancestors == NULL) {
1662                 /* if there is no common ancestor, make an empty tree */
1663                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1664
1665                 tree->object.parsed = 1;
1666                 tree->object.type = OBJ_TREE;
1667                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1668                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1669         }
1670
1671         for (iter = ca; iter; iter = iter->next) {
1672                 const char *saved_b1, *saved_b2;
1673                 o->call_depth++;
1674                 /*
1675                  * When the merge fails, the result contains files
1676                  * with conflict markers. The cleanness flag is
1677                  * ignored, it was never actually used, as result of
1678                  * merge_trees has always overwritten it: the committed
1679                  * "conflicts" were already resolved.
1680                  */
1681                 discard_cache();
1682                 saved_b1 = o->branch1;
1683                 saved_b2 = o->branch2;
1684                 o->branch1 = "Temporary merge branch 1";
1685                 o->branch2 = "Temporary merge branch 2";
1686                 merge_recursive(o, merged_common_ancestors, iter->item,
1687                                 NULL, &merged_common_ancestors);
1688                 o->branch1 = saved_b1;
1689                 o->branch2 = saved_b2;
1690                 o->call_depth--;
1691
1692                 if (!merged_common_ancestors)
1693                         die("merge returned no commit");
1694         }
1695
1696         discard_cache();
1697         if (!o->call_depth)
1698                 read_cache();
1699
1700         o->ancestor = "merged common ancestors";
1701         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
1702                             &mrtree);
1703
1704         if (o->call_depth) {
1705                 *result = make_virtual_commit(mrtree, "merged tree");
1706                 commit_list_insert(h1, &(*result)->parents);
1707                 commit_list_insert(h2, &(*result)->parents->next);
1708         }
1709         flush_output(o);
1710         if (show(o, 2))
1711                 diff_warn_rename_limit("merge.renamelimit",
1712                                        o->needed_rename_limit, 0);
1713         return clean;
1714 }
1715
1716 static struct commit *get_ref(const unsigned char *sha1, const char *name)
1717 {
1718         struct object *object;
1719
1720         object = deref_tag(parse_object(sha1), name, strlen(name));
1721         if (!object)
1722                 return NULL;
1723         if (object->type == OBJ_TREE)
1724                 return make_virtual_commit((struct tree*)object, name);
1725         if (object->type != OBJ_COMMIT)
1726                 return NULL;
1727         if (parse_commit((struct commit *)object))
1728                 return NULL;
1729         return (struct commit *)object;
1730 }
1731
1732 int merge_recursive_generic(struct merge_options *o,
1733                             const unsigned char *head,
1734                             const unsigned char *merge,
1735                             int num_base_list,
1736                             const unsigned char **base_list,
1737                             struct commit **result)
1738 {
1739         int clean, index_fd;
1740         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1741         struct commit *head_commit = get_ref(head, o->branch1);
1742         struct commit *next_commit = get_ref(merge, o->branch2);
1743         struct commit_list *ca = NULL;
1744
1745         if (base_list) {
1746                 int i;
1747                 for (i = 0; i < num_base_list; ++i) {
1748                         struct commit *base;
1749                         if (!(base = get_ref(base_list[i], sha1_to_hex(base_list[i]))))
1750                                 return error("Could not parse object '%s'",
1751                                         sha1_to_hex(base_list[i]));
1752                         commit_list_insert(base, &ca);
1753                 }
1754         }
1755
1756         index_fd = hold_locked_index(lock, 1);
1757         clean = merge_recursive(o, head_commit, next_commit, ca,
1758                         result);
1759         if (active_cache_changed &&
1760                         (write_cache(index_fd, active_cache, active_nr) ||
1761                          commit_locked_index(lock)))
1762                 return error("Unable to write index.");
1763
1764         return clean ? 0 : 1;
1765 }
1766
1767 static int merge_recursive_config(const char *var, const char *value, void *cb)
1768 {
1769         struct merge_options *o = cb;
1770         if (!strcmp(var, "merge.verbosity")) {
1771                 o->verbosity = git_config_int(var, value);
1772                 return 0;
1773         }
1774         if (!strcmp(var, "diff.renamelimit")) {
1775                 o->diff_rename_limit = git_config_int(var, value);
1776                 return 0;
1777         }
1778         if (!strcmp(var, "merge.renamelimit")) {
1779                 o->merge_rename_limit = git_config_int(var, value);
1780                 return 0;
1781         }
1782         return git_xmerge_config(var, value, cb);
1783 }
1784
1785 void init_merge_options(struct merge_options *o)
1786 {
1787         memset(o, 0, sizeof(struct merge_options));
1788         o->verbosity = 2;
1789         o->buffer_output = 1;
1790         o->diff_rename_limit = -1;
1791         o->merge_rename_limit = -1;
1792         o->renormalize = 0;
1793         git_config(merge_recursive_config, o);
1794         if (getenv("GIT_MERGE_VERBOSITY"))
1795                 o->verbosity =
1796                         strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1797         if (o->verbosity >= 5)
1798                 o->buffer_output = 0;
1799         strbuf_init(&o->obuf, 0);
1800         memset(&o->current_file_set, 0, sizeof(struct string_list));
1801         o->current_file_set.strdup_strings = 1;
1802         memset(&o->current_directory_set, 0, sizeof(struct string_list));
1803         o->current_directory_set.strdup_strings = 1;
1804         memset(&o->df_conflict_file_set, 0, sizeof(struct string_list));
1805         o->df_conflict_file_set.strdup_strings = 1;
1806 }
1807
1808 int parse_merge_opt(struct merge_options *o, const char *s)
1809 {
1810         if (!s || !*s)
1811                 return -1;
1812         if (!strcmp(s, "ours"))
1813                 o->recursive_variant = MERGE_RECURSIVE_OURS;
1814         else if (!strcmp(s, "theirs"))
1815                 o->recursive_variant = MERGE_RECURSIVE_THEIRS;
1816         else if (!strcmp(s, "subtree"))
1817                 o->subtree_shift = "";
1818         else if (!prefixcmp(s, "subtree="))
1819                 o->subtree_shift = s + strlen("subtree=");
1820         else if (!strcmp(s, "patience"))
1821                 o->xdl_opts |= XDF_PATIENCE_DIFF;
1822         else if (!strcmp(s, "ignore-space-change"))
1823                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_CHANGE;
1824         else if (!strcmp(s, "ignore-all-space"))
1825                 o->xdl_opts |= XDF_IGNORE_WHITESPACE;
1826         else if (!strcmp(s, "ignore-space-at-eol"))
1827                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_AT_EOL;
1828         else if (!strcmp(s, "renormalize"))
1829                 o->renormalize = 1;
1830         else if (!strcmp(s, "no-renormalize"))
1831                 o->renormalize = 0;
1832         else if (!prefixcmp(s, "rename-threshold=")) {
1833                 const char *score = s + strlen("rename-threshold=");
1834                 if ((o->rename_score = parse_rename_score(&score)) == -1 || *score != 0)
1835                         return -1;
1836         }
1837         else
1838                 return -1;
1839         return 0;
1840 }