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 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  42 {
  43         struct commit *commit = xcalloc(1, sizeof(struct commit));
  44         struct merge_remote_desc *desc = xmalloc(sizeof(*desc));
  45
  46         desc->name = comment;
  47         desc->obj = (struct object *)commit;
  48         commit->tree = tree;
  49         commit->util = desc;
  50         commit->object.parsed = 1;
  51         return commit;
  52 }
  53
  54 /*
  55  * Since we use get_tree_entry(), which does not put the read object into
  56  * the object pool, we cannot rely on a == b.
  57  */
  58 static int sha_eq(const unsigned char *a, const unsigned char *b)
  59 {
  60         if (!a && !b)
  61                 return 2;
  62         return a && b && hashcmp(a, b) == 0;
  63 }
  64
  65 enum rename_type {
  66         RENAME_NORMAL = 0,
  67         RENAME_DELETE,
  68         RENAME_ONE_FILE_TO_ONE,
  69         RENAME_ONE_FILE_TO_TWO,
  70         RENAME_TWO_FILES_TO_ONE
  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         struct diff_filespec ren1_other;
  82         struct diff_filespec ren2_other;
  83 };
  84
  85 /*
  86  * Since we want to write the index eventually, we cannot reuse the index
  87  * for these (temporary) data.
  88  */
  89 struct stage_data {
  90         struct {
  91                 unsigned mode;
  92                 unsigned char sha[20];
  93         } stages[4];
  94         struct rename_conflict_info *rename_conflict_info;
  95         unsigned processed:1;
  96 };
  97
  98 static inline void setup_rename_conflict_info(enum rename_type rename_type,
  99                                               struct diff_filepair *pair1,
 100                                               struct diff_filepair *pair2,
 101                                               const char *branch1,
 102                                               const char *branch2,
 103                                               struct stage_data *dst_entry1,
 104                                               struct stage_data *dst_entry2,
 105                                               struct merge_options *o,
 106                                               struct stage_data *src_entry1,
 107                                               struct stage_data *src_entry2)
 108 {
 109         struct rename_conflict_info *ci = xcalloc(1, sizeof(struct rename_conflict_info));
 110         ci->rename_type = rename_type;
 111         ci->pair1 = pair1;
 112         ci->branch1 = branch1;
 113         ci->branch2 = branch2;
 114
 115         ci->dst_entry1 = dst_entry1;
 116         dst_entry1->rename_conflict_info = ci;
 117         dst_entry1->processed = 0;
 118
 119         assert(!pair2 == !dst_entry2);
 120         if (dst_entry2) {
 121                 ci->dst_entry2 = dst_entry2;
 122                 ci->pair2 = pair2;
 123                 dst_entry2->rename_conflict_info = ci;
 124         }
 125
 126         if (rename_type == RENAME_TWO_FILES_TO_ONE) {
 127                 /*
 128                  * For each rename, there could have been
 129                  * modifications on the side of history where that
 130                  * file was not renamed.
 131                  */
 132                 int ostage1 = o->branch1 == branch1 ? 3 : 2;
 133                 int ostage2 = ostage1 ^ 1;
 134
 135                 ci->ren1_other.path = pair1->one->path;
 136                 hashcpy(ci->ren1_other.sha1, src_entry1->stages[ostage1].sha);
 137                 ci->ren1_other.mode = src_entry1->stages[ostage1].mode;
 138
 139                 ci->ren2_other.path = pair2->one->path;
 140                 hashcpy(ci->ren2_other.sha1, src_entry2->stages[ostage2].sha);
 141                 ci->ren2_other.mode = src_entry2->stages[ostage2].mode;
 142         }
 143 }
 144
 145 static int show(struct merge_options *o, int v)
 146 {
 147         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
 148 }
 149
 150 static void flush_output(struct merge_options *o)
 151 {
 152         if (o->obuf.len) {
 153                 fputs(o->obuf.buf, stdout);
 154                 strbuf_reset(&o->obuf);
 155         }
 156 }
 157
 158 __attribute__((format (printf, 3, 4)))
 159 static void output(struct merge_options *o, int v, const char *fmt, ...)
 160 {
 161         va_list ap;
 162
 163         if (!show(o, v))
 164                 return;
 165
 166         strbuf_grow(&o->obuf, o->call_depth * 2 + 2);
 167         memset(o->obuf.buf + o->obuf.len, ' ', o->call_depth * 2);
 168         strbuf_setlen(&o->obuf, o->obuf.len + o->call_depth * 2);
 169
 170         va_start(ap, fmt);
 171         strbuf_vaddf(&o->obuf, fmt, ap);
 172         va_end(ap);
 173
 174         strbuf_add(&o->obuf, "\n", 1);
 175         if (!o->buffer_output)
 176                 flush_output(o);
 177 }
 178
 179 static void output_commit_title(struct merge_options *o, struct commit *commit)
 180 {
 181         int i;
 182         flush_output(o);
 183         for (i = o->call_depth; i--;)
 184                 fputs("  ", stdout);
 185         if (commit->util)
 186                 printf("virtual %s\n", merge_remote_util(commit)->name);
 187         else {
 188                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 189                 if (parse_commit(commit) != 0)
 190                         printf("(bad commit)\n");
 191                 else {
 192                         const char *title;
 193                         int len = find_commit_subject(commit->buffer, &title);
 194                         if (len)
 195                                 printf("%.*s\n", len, title);
 196                 }
 197         }
 198 }
 199
 200 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 201                 const char *path, int stage, int refresh, int options)
 202 {
 203         struct cache_entry *ce;
 204         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 205         if (!ce)
 206                 return error("addinfo_cache failed for path '%s'", path);
 207         return add_cache_entry(ce, options);
 208 }
 209
 210 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 211 {
 212         parse_tree(tree);
 213         init_tree_desc(desc, tree->buffer, tree->size);
 214 }
 215
 216 static int git_merge_trees(int index_only,
 217                            struct tree *common,
 218                            struct tree *head,
 219                            struct tree *merge)
 220 {
 221         int rc;
 222         struct tree_desc t[3];
 223         struct unpack_trees_options opts;
 224
 225         memset(&opts, 0, sizeof(opts));
 226         if (index_only)
 227                 opts.index_only = 1;
 228         else
 229                 opts.update = 1;
 230         opts.merge = 1;
 231         opts.head_idx = 2;
 232         opts.fn = threeway_merge;
 233         opts.src_index = &the_index;
 234         opts.dst_index = &the_index;
 235         setup_unpack_trees_porcelain(&opts, "merge");
 236
 237         init_tree_desc_from_tree(t+0, common);
 238         init_tree_desc_from_tree(t+1, head);
 239         init_tree_desc_from_tree(t+2, merge);
 240
 241         rc = unpack_trees(3, t, &opts);
 242         cache_tree_free(&active_cache_tree);
 243         return rc;
 244 }
 245
 246 struct tree *write_tree_from_memory(struct merge_options *o)
 247 {
 248         struct tree *result = NULL;
 249
 250         if (unmerged_cache()) {
 251                 int i;
 252                 fprintf(stderr, "BUG: There are unmerged index entries:\n");
 253                 for (i = 0; i < active_nr; i++) {
 254                         struct cache_entry *ce = active_cache[i];
 255                         if (ce_stage(ce))
 256                                 fprintf(stderr, "BUG: %d %.*s\n", ce_stage(ce),
 257                                         (int)ce_namelen(ce), ce->name);
 258                 }
 259                 die("Bug in merge-recursive.c");
 260         }
 261
 262         if (!active_cache_tree)
 263                 active_cache_tree = cache_tree();
 264
 265         if (!cache_tree_fully_valid(active_cache_tree) &&
 266             cache_tree_update(active_cache_tree,
 267                               active_cache, active_nr, 0) < 0)
 268                 die("error building trees");
 269
 270         result = lookup_tree(active_cache_tree->sha1);
 271
 272         return result;
 273 }
 274
 275 static int save_files_dirs(const unsigned char *sha1,
 276                 const char *base, int baselen, const char *path,
 277                 unsigned int mode, int stage, void *context)
 278 {
 279         int len = strlen(path);
 280         char *newpath = xmalloc(baselen + len + 1);
 281         struct merge_options *o = context;
 282
 283         memcpy(newpath, base, baselen);
 284         memcpy(newpath + baselen, path, len);
 285         newpath[baselen + len] = '\0';
 286
 287         if (S_ISDIR(mode))
 288                 string_list_insert(&o->current_directory_set, newpath);
 289         else
 290                 string_list_insert(&o->current_file_set, newpath);
 291         free(newpath);
 292
 293         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
 294 }
 295
 296 static int get_files_dirs(struct merge_options *o, struct tree *tree)
 297 {
 298         int n;
 299         struct pathspec match_all;
 300         init_pathspec(&match_all, NULL);
 301         if (read_tree_recursive(tree, "", 0, 0, &match_all, save_files_dirs, o))
 302                 return 0;
 303         n = o->current_file_set.nr + o->current_directory_set.nr;
 304         return n;
 305 }
 306
 307 /*
 308  * Returns an index_entry instance which doesn't have to correspond to
 309  * a real cache entry in Git's index.
 310  */
 311 static struct stage_data *insert_stage_data(const char *path,
 312                 struct tree *o, struct tree *a, struct tree *b,
 313                 struct string_list *entries)
 314 {
 315         struct string_list_item *item;
 316         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 317         get_tree_entry(o->object.sha1, path,
 318                         e->stages[1].sha, &e->stages[1].mode);
 319         get_tree_entry(a->object.sha1, path,
 320                         e->stages[2].sha, &e->stages[2].mode);
 321         get_tree_entry(b->object.sha1, path,
 322                         e->stages[3].sha, &e->stages[3].mode);
 323         item = string_list_insert(entries, path);
 324         item->util = e;
 325         return e;
 326 }
 327
 328 /*
 329  * Create a dictionary mapping file names to stage_data objects. The
 330  * dictionary contains one entry for every path with a non-zero stage entry.
 331  */
 332 static struct string_list *get_unmerged(void)
 333 {
 334         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
 335         int i;
 336
 337         unmerged->strdup_strings = 1;
 338
 339         for (i = 0; i < active_nr; i++) {
 340                 struct string_list_item *item;
 341                 struct stage_data *e;
 342                 struct cache_entry *ce = active_cache[i];
 343                 if (!ce_stage(ce))
 344                         continue;
 345
 346                 item = string_list_lookup(unmerged, ce->name);
 347                 if (!item) {
 348                         item = string_list_insert(unmerged, ce->name);
 349                         item->util = xcalloc(1, sizeof(struct stage_data));
 350                 }
 351                 e = item->util;
 352                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
 353                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 354         }
 355
 356         return unmerged;
 357 }
 358
 359 static int string_list_df_name_compare(const void *a, const void *b)
 360 {
 361         const struct string_list_item *one = a;
 362         const struct string_list_item *two = b;
 363         int onelen = strlen(one->string);
 364         int twolen = strlen(two->string);
 365         /*
 366          * Here we only care that entries for D/F conflicts are
 367          * adjacent, in particular with the file of the D/F conflict
 368          * appearing before files below the corresponding directory.
 369          * The order of the rest of the list is irrelevant for us.
 370          *
 371          * To achieve this, we sort with df_name_compare and provide
 372          * the mode S_IFDIR so that D/F conflicts will sort correctly.
 373          * We use the mode S_IFDIR for everything else for simplicity,
 374          * since in other cases any changes in their order due to
 375          * sorting cause no problems for us.
 376          */
 377         int cmp = df_name_compare(one->string, onelen, S_IFDIR,
 378                                   two->string, twolen, S_IFDIR);
 379         /*
 380          * Now that 'foo' and 'foo/bar' compare equal, we have to make sure
 381          * that 'foo' comes before 'foo/bar'.
 382          */
 383         if (cmp)
 384                 return cmp;
 385         return onelen - twolen;
 386 }
 387
 388 static void record_df_conflict_files(struct merge_options *o,
 389                                      struct string_list *entries)
 390 {
 391         /* If there is a D/F conflict and the file for such a conflict
 392          * currently exist in the working tree, we want to allow it to be
 393          * removed to make room for the corresponding directory if needed.
 394          * The files underneath the directories of such D/F conflicts will
 395          * be processed before the corresponding file involved in the D/F
 396          * conflict.  If the D/F directory ends up being removed by the
 397          * merge, then we won't have to touch the D/F file.  If the D/F
 398          * directory needs to be written to the working copy, then the D/F
 399          * file will simply be removed (in make_room_for_path()) to make
 400          * room for the necessary paths.  Note that if both the directory
 401          * and the file need to be present, then the D/F file will be
 402          * reinstated with a new unique name at the time it is processed.
 403          */
 404         struct string_list df_sorted_entries;
 405         const char *last_file = NULL;
 406         int last_len = 0;
 407         int i;
 408
 409         /*
 410          * If we're merging merge-bases, we don't want to bother with
 411          * any working directory changes.
 412          */
 413         if (o->call_depth)
 414                 return;
 415
 416         /* Ensure D/F conflicts are adjacent in the entries list. */
 417         memset(&df_sorted_entries, 0, sizeof(struct string_list));
 418         for (i = 0; i < entries->nr; i++) {
 419                 struct string_list_item *next = &entries->items[i];
 420                 string_list_append(&df_sorted_entries, next->string)->util =
 421                                    next->util;
 422         }
 423         qsort(df_sorted_entries.items, entries->nr, sizeof(*entries->items),
 424               string_list_df_name_compare);
 425
 426         string_list_clear(&o->df_conflict_file_set, 1);
 427         for (i = 0; i < df_sorted_entries.nr; i++) {
 428                 const char *path = df_sorted_entries.items[i].string;
 429                 int len = strlen(path);
 430                 struct stage_data *e = df_sorted_entries.items[i].util;
 431
 432                 /*
 433                  * Check if last_file & path correspond to a D/F conflict;
 434                  * i.e. whether path is last_file+'/'+<something>.
 435                  * If so, record that it's okay to remove last_file to make
 436                  * room for path and friends if needed.
 437                  */
 438                 if (last_file &&
 439                     len > last_len &&
 440                     memcmp(path, last_file, last_len) == 0 &&
 441                     path[last_len] == '/') {
 442                         string_list_insert(&o->df_conflict_file_set, last_file);
 443                 }
 444
 445                 /*
 446                  * Determine whether path could exist as a file in the
 447                  * working directory as a possible D/F conflict.  This
 448                  * will only occur when it exists in stage 2 as a
 449                  * file.
 450                  */
 451                 if (S_ISREG(e->stages[2].mode) || S_ISLNK(e->stages[2].mode)) {
 452                         last_file = path;
 453                         last_len = len;
 454                 } else {
 455                         last_file = NULL;
 456                 }
 457         }
 458         string_list_clear(&df_sorted_entries, 0);
 459 }
 460
 461 struct rename {
 462         struct diff_filepair *pair;
 463         struct stage_data *src_entry;
 464         struct stage_data *dst_entry;
 465         unsigned processed:1;
 466 };
 467
 468 /*
 469  * Get information of all renames which occurred between 'o_tree' and
 470  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 471  * 'b_tree') to be able to associate the correct cache entries with
 472  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 473  */
 474 static struct string_list *get_renames(struct merge_options *o,
 475                                        struct tree *tree,
 476                                        struct tree *o_tree,
 477                                        struct tree *a_tree,
 478                                        struct tree *b_tree,
 479                                        struct string_list *entries)
 480 {
 481         int i;
 482         struct string_list *renames;
 483         struct diff_options opts;
 484
 485         renames = xcalloc(1, sizeof(struct string_list));
 486         diff_setup(&opts);
 487         DIFF_OPT_SET(&opts, RECURSIVE);
 488         DIFF_OPT_CLR(&opts, RENAME_EMPTY);
 489         opts.detect_rename = DIFF_DETECT_RENAME;
 490         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 491                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 492                             1000;
 493         opts.rename_score = o->rename_score;
 494         opts.show_rename_progress = o->show_rename_progress;
 495         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 496         diff_setup_done(&opts);
 497         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 498         diffcore_std(&opts);
 499         if (opts.needed_rename_limit > o->needed_rename_limit)
 500                 o->needed_rename_limit = opts.needed_rename_limit;
 501         for (i = 0; i < diff_queued_diff.nr; ++i) {
 502                 struct string_list_item *item;
 503                 struct rename *re;
 504                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 505                 if (pair->status != 'R') {
 506                         diff_free_filepair(pair);
 507                         continue;
 508                 }
 509                 re = xmalloc(sizeof(*re));
 510                 re->processed = 0;
 511                 re->pair = pair;
 512                 item = string_list_lookup(entries, re->pair->one->path);
 513                 if (!item)
 514                         re->src_entry = insert_stage_data(re->pair->one->path,
 515                                         o_tree, a_tree, b_tree, entries);
 516                 else
 517                         re->src_entry = item->util;
 518
 519                 item = string_list_lookup(entries, re->pair->two->path);
 520                 if (!item)
 521                         re->dst_entry = insert_stage_data(re->pair->two->path,
 522                                         o_tree, a_tree, b_tree, entries);
 523                 else
 524                         re->dst_entry = item->util;
 525                 item = string_list_insert(renames, pair->one->path);
 526                 item->util = re;
 527         }
 528         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 529         diff_queued_diff.nr = 0;
 530         diff_flush(&opts);
 531         return renames;
 532 }
 533
 534 static int update_stages(const char *path, const struct diff_filespec *o,
 535                          const struct diff_filespec *a,
 536                          const struct diff_filespec *b)
 537 {
 538
 539         /*
 540          * NOTE: It is usually a bad idea to call update_stages on a path
 541          * before calling update_file on that same path, since it can
 542          * sometimes lead to spurious "refusing to lose untracked file..."
 543          * messages from update_file (via make_room_for path via
 544          * would_lose_untracked).  Instead, reverse the order of the calls
 545          * (executing update_file first and then update_stages).
 546          */
 547         int clear = 1;
 548         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_SKIP_DFCHECK;
 549         if (clear)
 550                 if (remove_file_from_cache(path))
 551                         return -1;
 552         if (o)
 553                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 554                         return -1;
 555         if (a)
 556                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 557                         return -1;
 558         if (b)
 559                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 560                         return -1;
 561         return 0;
 562 }
 563
 564 static void update_entry(struct stage_data *entry,
 565                          struct diff_filespec *o,
 566                          struct diff_filespec *a,
 567                          struct diff_filespec *b)
 568 {
 569         entry->processed = 0;
 570         entry->stages[1].mode = o->mode;
 571         entry->stages[2].mode = a->mode;
 572         entry->stages[3].mode = b->mode;
 573         hashcpy(entry->stages[1].sha, o->sha1);
 574         hashcpy(entry->stages[2].sha, a->sha1);
 575         hashcpy(entry->stages[3].sha, b->sha1);
 576 }
 577
 578 static int remove_file(struct merge_options *o, int clean,
 579                        const char *path, int no_wd)
 580 {
 581         int update_cache = o->call_depth || clean;
 582         int update_working_directory = !o->call_depth && !no_wd;
 583
 584         if (update_cache) {
 585                 if (remove_file_from_cache(path))
 586                         return -1;
 587         }
 588         if (update_working_directory) {
 589                 if (remove_path(path))
 590                         return -1;
 591         }
 592         return 0;
 593 }
 594
 595 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
 596 {
 597         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 598         int suffix = 0;
 599         struct stat st;
 600         char *p = newpath + strlen(path);
 601         strcpy(newpath, path);
 602         *(p++) = '~';
 603         strcpy(p, branch);
 604         for (; *p; ++p)
 605                 if ('/' == *p)
 606                         *p = '_';
 607         while (string_list_has_string(&o->current_file_set, newpath) ||
 608                string_list_has_string(&o->current_directory_set, newpath) ||
 609                lstat(newpath, &st) == 0)
 610                 sprintf(p, "_%d", suffix++);
 611
 612         string_list_insert(&o->current_file_set, newpath);
 613         return newpath;
 614 }
 615
 616 static int dir_in_way(const char *path, int check_working_copy)
 617 {
 618         int pos, pathlen = strlen(path);
 619         char *dirpath = xmalloc(pathlen + 2);
 620         struct stat st;
 621
 622         strcpy(dirpath, path);
 623         dirpath[pathlen] = '/';
 624         dirpath[pathlen+1] = '\0';
 625
 626         pos = cache_name_pos(dirpath, pathlen+1);
 627
 628         if (pos < 0)
 629                 pos = -1 - pos;
 630         if (pos < active_nr &&
 631             !strncmp(dirpath, active_cache[pos]->name, pathlen+1)) {
 632                 free(dirpath);
 633                 return 1;
 634         }
 635
 636         free(dirpath);
 637         return check_working_copy && !lstat(path, &st) && S_ISDIR(st.st_mode);
 638 }
 639
 640 static int was_tracked(const char *path)
 641 {
 642         int pos = cache_name_pos(path, strlen(path));
 643
 644         if (pos < 0)
 645                 pos = -1 - pos;
 646         while (pos < active_nr &&
 647                !strcmp(path, active_cache[pos]->name)) {
 648                 /*
 649                  * If stage #0, it is definitely tracked.
 650                  * If it has stage #2 then it was tracked
 651                  * before this merge started.  All other
 652                  * cases the path was not tracked.
 653                  */
 654                 switch (ce_stage(active_cache[pos])) {
 655                 case 0:
 656                 case 2:
 657                         return 1;
 658                 }
 659                 pos++;
 660         }
 661         return 0;
 662 }
 663
 664 static int would_lose_untracked(const char *path)
 665 {
 666         return !was_tracked(path) && file_exists(path);
 667 }
 668
 669 static int make_room_for_path(struct merge_options *o, const char *path)
 670 {
 671         int status, i;
 672         const char *msg = "failed to create path '%s'%s";
 673
 674         /* Unlink any D/F conflict files that are in the way */
 675         for (i = 0; i < o->df_conflict_file_set.nr; i++) {
 676                 const char *df_path = o->df_conflict_file_set.items[i].string;
 677                 size_t pathlen = strlen(path);
 678                 size_t df_pathlen = strlen(df_path);
 679                 if (df_pathlen < pathlen &&
 680                     path[df_pathlen] == '/' &&
 681                     strncmp(path, df_path, df_pathlen) == 0) {
 682                         output(o, 3,
 683                                "Removing %s to make room for subdirectory\n",
 684                                df_path);
 685                         unlink(df_path);
 686                         unsorted_string_list_delete_item(&o->df_conflict_file_set,
 687                                                          i, 0);
 688                         break;
 689                 }
 690         }
 691
 692         /* Make sure leading directories are created */
 693         status = safe_create_leading_directories_const(path);
 694         if (status) {
 695                 if (status == -3) {
 696                         /* something else exists */
 697                         error(msg, path, ": perhaps a D/F conflict?");
 698                         return -1;
 699                 }
 700                 die(msg, path, "");
 701         }
 702
 703         /*
 704          * Do not unlink a file in the work tree if we are not
 705          * tracking it.
 706          */
 707         if (would_lose_untracked(path))
 708                 return error("refusing to lose untracked file at '%s'",
 709                              path);
 710
 711         /* Successful unlink is good.. */
 712         if (!unlink(path))
 713                 return 0;
 714         /* .. and so is no existing file */
 715         if (errno == ENOENT)
 716                 return 0;
 717         /* .. but not some other error (who really cares what?) */
 718         return error(msg, path, ": perhaps a D/F conflict?");
 719 }
 720
 721 static void update_file_flags(struct merge_options *o,
 722                               const unsigned char *sha,
 723                               unsigned mode,
 724                               const char *path,
 725                               int update_cache,
 726                               int update_wd)
 727 {
 728         if (o->call_depth)
 729                 update_wd = 0;
 730
 731         if (update_wd) {
 732                 enum object_type type;
 733                 void *buf;
 734                 unsigned long size;
 735
 736                 if (S_ISGITLINK(mode)) {
 737                         /*
 738                          * We may later decide to recursively descend into
 739                          * the submodule directory and update its index
 740                          * and/or work tree, but we do not do that now.
 741                          */
 742                         update_wd = 0;
 743                         goto update_index;
 744                 }
 745
 746                 buf = read_sha1_file(sha, &type, &size);
 747                 if (!buf)
 748                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 749                 if (type != OBJ_BLOB)
 750                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 751                 if (S_ISREG(mode)) {
 752                         struct strbuf strbuf = STRBUF_INIT;
 753                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
 754                                 free(buf);
 755                                 size = strbuf.len;
 756                                 buf = strbuf_detach(&strbuf, NULL);
 757                         }
 758                 }
 759
 760                 if (make_room_for_path(o, path) < 0) {
 761                         update_wd = 0;
 762                         free(buf);
 763                         goto update_index;
 764                 }
 765                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 766                         int fd;
 767                         if (mode & 0100)
 768                                 mode = 0777;
 769                         else
 770                                 mode = 0666;
 771                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 772                         if (fd < 0)
 773                                 die_errno("failed to open '%s'", path);
 774                         write_in_full(fd, buf, size);
 775                         close(fd);
 776                 } else if (S_ISLNK(mode)) {
 777                         char *lnk = xmemdupz(buf, size);
 778                         safe_create_leading_directories_const(path);
 779                         unlink(path);
 780                         if (symlink(lnk, path))
 781                                 die_errno("failed to symlink '%s'", path);
 782                         free(lnk);
 783                 } else
 784                         die("do not know what to do with %06o %s '%s'",
 785                             mode, sha1_to_hex(sha), path);
 786                 free(buf);
 787         }
 788  update_index:
 789         if (update_cache)
 790                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 791 }
 792
 793 static void update_file(struct merge_options *o,
 794                         int clean,
 795                         const unsigned char *sha,
 796                         unsigned mode,
 797                         const char *path)
 798 {
 799         update_file_flags(o, sha, mode, path, o->call_depth || clean, !o->call_depth);
 800 }
 801
 802 /* Low level file merging, update and removal */
 803
 804 struct merge_file_info {
 805         unsigned char sha[20];
 806         unsigned mode;
 807         unsigned clean:1,
 808                  merge:1;
 809 };
 810
 811 static int merge_3way(struct merge_options *o,
 812                       mmbuffer_t *result_buf,
 813                       const struct diff_filespec *one,
 814                       const struct diff_filespec *a,
 815                       const struct diff_filespec *b,
 816                       const char *branch1,
 817                       const char *branch2)
 818 {
 819         mmfile_t orig, src1, src2;
 820         struct ll_merge_options ll_opts = {0};
 821         char *base_name, *name1, *name2;
 822         int merge_status;
 823
 824         ll_opts.renormalize = o->renormalize;
 825         ll_opts.xdl_opts = o->xdl_opts;
 826
 827         if (o->call_depth) {
 828                 ll_opts.virtual_ancestor = 1;
 829                 ll_opts.variant = 0;
 830         } else {
 831                 switch (o->recursive_variant) {
 832                 case MERGE_RECURSIVE_OURS:
 833                         ll_opts.variant = XDL_MERGE_FAVOR_OURS;
 834                         break;
 835                 case MERGE_RECURSIVE_THEIRS:
 836                         ll_opts.variant = XDL_MERGE_FAVOR_THEIRS;
 837                         break;
 838                 default:
 839                         ll_opts.variant = 0;
 840                         break;
 841                 }
 842         }
 843
 844         if (strcmp(a->path, b->path) ||
 845             (o->ancestor != NULL && strcmp(a->path, one->path) != 0)) {
 846                 base_name = o->ancestor == NULL ? NULL :
 847                         xstrdup(mkpath("%s:%s", o->ancestor, one->path));
 848                 name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 849                 name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 850         } else {
 851                 base_name = o->ancestor == NULL ? NULL :
 852                         xstrdup(mkpath("%s", o->ancestor));
 853                 name1 = xstrdup(mkpath("%s", branch1));
 854                 name2 = xstrdup(mkpath("%s", branch2));
 855         }
 856
 857         read_mmblob(&orig, one->sha1);
 858         read_mmblob(&src1, a->sha1);
 859         read_mmblob(&src2, b->sha1);
 860
 861         merge_status = ll_merge(result_buf, a->path, &orig, base_name,
 862                                 &src1, name1, &src2, name2, &ll_opts);
 863
 864         free(name1);
 865         free(name2);
 866         free(orig.ptr);
 867         free(src1.ptr);
 868         free(src2.ptr);
 869         return merge_status;
 870 }
 871
 872 static struct merge_file_info merge_file_1(struct merge_options *o,
 873                                            const struct diff_filespec *one,
 874                                            const struct diff_filespec *a,
 875                                            const struct diff_filespec *b,
 876                                            const char *branch1,
 877                                            const char *branch2)
 878 {
 879         struct merge_file_info result;
 880         result.merge = 0;
 881         result.clean = 1;
 882
 883         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 884                 result.clean = 0;
 885                 if (S_ISREG(a->mode)) {
 886                         result.mode = a->mode;
 887                         hashcpy(result.sha, a->sha1);
 888                 } else {
 889                         result.mode = b->mode;
 890                         hashcpy(result.sha, b->sha1);
 891                 }
 892         } else {
 893                 if (!sha_eq(a->sha1, one->sha1) && !sha_eq(b->sha1, one->sha1))
 894                         result.merge = 1;
 895
 896                 /*
 897                  * Merge modes
 898                  */
 899                 if (a->mode == b->mode || a->mode == one->mode)
 900                         result.mode = b->mode;
 901                 else {
 902                         result.mode = a->mode;
 903                         if (b->mode != one->mode) {
 904                                 result.clean = 0;
 905                                 result.merge = 1;
 906                         }
 907                 }
 908
 909                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, one->sha1))
 910                         hashcpy(result.sha, b->sha1);
 911                 else if (sha_eq(b->sha1, one->sha1))
 912                         hashcpy(result.sha, a->sha1);
 913                 else if (S_ISREG(a->mode)) {
 914                         mmbuffer_t result_buf;
 915                         int merge_status;
 916
 917                         merge_status = merge_3way(o, &result_buf, one, a, b,
 918                                                   branch1, branch2);
 919
 920                         if ((merge_status < 0) || !result_buf.ptr)
 921                                 die("Failed to execute internal merge");
 922
 923                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 924                                             blob_type, result.sha))
 925                                 die("Unable to add %s to database",
 926                                     a->path);
 927
 928                         free(result_buf.ptr);
 929                         result.clean = (merge_status == 0);
 930                 } else if (S_ISGITLINK(a->mode)) {
 931                         result.clean = merge_submodule(result.sha,
 932                                                        one->path, one->sha1,
 933                                                        a->sha1, b->sha1,
 934                                                        !o->call_depth);
 935                 } else if (S_ISLNK(a->mode)) {
 936                         hashcpy(result.sha, a->sha1);
 937
 938                         if (!sha_eq(a->sha1, b->sha1))
 939                                 result.clean = 0;
 940                 } else {
 941                         die("unsupported object type in the tree");
 942                 }
 943         }
 944
 945         return result;
 946 }
 947
 948 static struct merge_file_info
 949 merge_file_special_markers(struct merge_options *o,
 950                            const struct diff_filespec *one,
 951                            const struct diff_filespec *a,
 952                            const struct diff_filespec *b,
 953                            const char *branch1,
 954                            const char *filename1,
 955                            const char *branch2,
 956                            const char *filename2)
 957 {
 958         char *side1 = NULL;
 959         char *side2 = NULL;
 960         struct merge_file_info mfi;
 961
 962         if (filename1) {
 963                 side1 = xmalloc(strlen(branch1) + strlen(filename1) + 2);
 964                 sprintf(side1, "%s:%s", branch1, filename1);
 965         }
 966         if (filename2) {
 967                 side2 = xmalloc(strlen(branch2) + strlen(filename2) + 2);
 968                 sprintf(side2, "%s:%s", branch2, filename2);
 969         }
 970
 971         mfi = merge_file_1(o, one, a, b,
 972                            side1 ? side1 : branch1, side2 ? side2 : branch2);
 973         free(side1);
 974         free(side2);
 975         return mfi;
 976 }
 977
 978 static struct merge_file_info merge_file(struct merge_options *o,
 979                                          const char *path,
 980                                          const unsigned char *o_sha, int o_mode,
 981                                          const unsigned char *a_sha, int a_mode,
 982                                          const unsigned char *b_sha, int b_mode,
 983                                          const char *branch1,
 984                                          const char *branch2)
 985 {
 986         struct diff_filespec one, a, b;
 987
 988         one.path = a.path = b.path = (char *)path;
 989         hashcpy(one.sha1, o_sha);
 990         one.mode = o_mode;
 991         hashcpy(a.sha1, a_sha);
 992         a.mode = a_mode;
 993         hashcpy(b.sha1, b_sha);
 994         b.mode = b_mode;
 995         return merge_file_1(o, &one, &a, &b, branch1, branch2);
 996 }
 997
 998 static void handle_change_delete(struct merge_options *o,
 999                                  const char *path,
1000                                  const unsigned char *o_sha, int o_mode,
1001                                  const unsigned char *a_sha, int a_mode,
1002                                  const unsigned char *b_sha, int b_mode,
1003                                  const char *change, const char *change_past)
1004 {
1005         char *renamed = NULL;
1006         if (dir_in_way(path, !o->call_depth)) {
1007                 renamed = unique_path(o, path, a_sha ? o->branch1 : o->branch2);
1008         }
1009
1010         if (o->call_depth) {
1011                 /*
1012                  * We cannot arbitrarily accept either a_sha or b_sha as
1013                  * correct; since there is no true "middle point" between
1014                  * them, simply reuse the base version for virtual merge base.
1015                  */
1016                 remove_file_from_cache(path);
1017                 update_file(o, 0, o_sha, o_mode, renamed ? renamed : path);
1018         } else if (!a_sha) {
1019                 output(o, 1, "CONFLICT (%s/delete): %s deleted in %s "
1020                        "and %s in %s. Version %s of %s left in tree%s%s.",
1021                        change, path, o->branch1,
1022                        change_past, o->branch2, o->branch2, path,
1023                        NULL == renamed ? "" : " at ",
1024                        NULL == renamed ? "" : renamed);
1025                 update_file(o, 0, b_sha, b_mode, renamed ? renamed : path);
1026         } else {
1027                 output(o, 1, "CONFLICT (%s/delete): %s deleted in %s "
1028                        "and %s in %s. Version %s of %s left in tree%s%s.",
1029                        change, path, o->branch2,
1030                        change_past, o->branch1, o->branch1, path,
1031                        NULL == renamed ? "" : " at ",
1032                        NULL == renamed ? "" : renamed);
1033                 if (renamed)
1034                         update_file(o, 0, a_sha, a_mode, renamed);
1035                 /*
1036                  * No need to call update_file() on path when !renamed, since
1037                  * that would needlessly touch path.  We could call
1038                  * update_file_flags() with update_cache=0 and update_wd=0,
1039                  * but that's a no-op.
1040                  */
1041         }
1042         free(renamed);
1043 }
1044
1045 static void conflict_rename_delete(struct merge_options *o,
1046                                    struct diff_filepair *pair,
1047                                    const char *rename_branch,
1048                                    const char *other_branch)
1049 {
1050         const struct diff_filespec *orig = pair->one;
1051         const struct diff_filespec *dest = pair->two;
1052         const unsigned char *a_sha = NULL;
1053         const unsigned char *b_sha = NULL;
1054         int a_mode = 0;
1055         int b_mode = 0;
1056
1057         if (rename_branch == o->branch1) {
1058                 a_sha = dest->sha1;
1059                 a_mode = dest->mode;
1060         } else {
1061                 b_sha = dest->sha1;
1062                 b_mode = dest->mode;
1063         }
1064
1065         handle_change_delete(o,
1066                              o->call_depth ? orig->path : dest->path,
1067                              orig->sha1, orig->mode,
1068                              a_sha, a_mode,
1069                              b_sha, b_mode,
1070                              "rename", "renamed");
1071
1072         if (o->call_depth) {
1073                 remove_file_from_cache(dest->path);
1074         } else {
1075                 update_stages(dest->path, NULL,
1076                               rename_branch == o->branch1 ? dest : NULL,
1077                               rename_branch == o->branch1 ? NULL : dest);
1078         }
1079
1080 }
1081
1082 static struct diff_filespec *filespec_from_entry(struct diff_filespec *target,
1083                                                  struct stage_data *entry,
1084                                                  int stage)
1085 {
1086         unsigned char *sha = entry->stages[stage].sha;
1087         unsigned mode = entry->stages[stage].mode;
1088         if (mode == 0 || is_null_sha1(sha))
1089                 return NULL;
1090         hashcpy(target->sha1, sha);
1091         target->mode = mode;
1092         return target;
1093 }
1094
1095 static void handle_file(struct merge_options *o,
1096                         struct diff_filespec *rename,
1097                         int stage,
1098                         struct rename_conflict_info *ci)
1099 {
1100         char *dst_name = rename->path;
1101         struct stage_data *dst_entry;
1102         const char *cur_branch, *other_branch;
1103         struct diff_filespec other;
1104         struct diff_filespec *add;
1105
1106         if (stage == 2) {
1107                 dst_entry = ci->dst_entry1;
1108                 cur_branch = ci->branch1;
1109                 other_branch = ci->branch2;
1110         } else {
1111                 dst_entry = ci->dst_entry2;
1112                 cur_branch = ci->branch2;
1113                 other_branch = ci->branch1;
1114         }
1115
1116         add = filespec_from_entry(&other, dst_entry, stage ^ 1);
1117         if (add) {
1118                 char *add_name = unique_path(o, rename->path, other_branch);
1119                 update_file(o, 0, add->sha1, add->mode, add_name);
1120
1121                 remove_file(o, 0, rename->path, 0);
1122                 dst_name = unique_path(o, rename->path, cur_branch);
1123         } else {
1124                 if (dir_in_way(rename->path, !o->call_depth)) {
1125                         dst_name = unique_path(o, rename->path, cur_branch);
1126                         output(o, 1, "%s is a directory in %s adding as %s instead",
1127                                rename->path, other_branch, dst_name);
1128                 }
1129         }
1130         update_file(o, 0, rename->sha1, rename->mode, dst_name);
1131         if (stage == 2)
1132                 update_stages(rename->path, NULL, rename, add);
1133         else
1134                 update_stages(rename->path, NULL, add, rename);
1135
1136         if (dst_name != rename->path)
1137                 free(dst_name);
1138 }
1139
1140 static void conflict_rename_rename_1to2(struct merge_options *o,
1141                                         struct rename_conflict_info *ci)
1142 {
1143         /* One file was renamed in both branches, but to different names. */
1144         struct diff_filespec *one = ci->pair1->one;
1145         struct diff_filespec *a = ci->pair1->two;
1146         struct diff_filespec *b = ci->pair2->two;
1147
1148         output(o, 1, "CONFLICT (rename/rename): "
1149                "Rename \"%s\"->\"%s\" in branch \"%s\" "
1150                "rename \"%s\"->\"%s\" in \"%s\"%s",
1151                one->path, a->path, ci->branch1,
1152                one->path, b->path, ci->branch2,
1153                o->call_depth ? " (left unresolved)" : "");
1154         if (o->call_depth) {
1155                 struct merge_file_info mfi;
1156                 struct diff_filespec other;
1157                 struct diff_filespec *add;
1158                 mfi = merge_file(o, one->path,
1159                                  one->sha1, one->mode,
1160                                  a->sha1, a->mode,
1161                                  b->sha1, b->mode,
1162                                  ci->branch1, ci->branch2);
1163                 /*
1164                  * FIXME: For rename/add-source conflicts (if we could detect
1165                  * such), this is wrong.  We should instead find a unique
1166                  * pathname and then either rename the add-source file to that
1167                  * unique path, or use that unique path instead of src here.
1168                  */
1169                 update_file(o, 0, mfi.sha, mfi.mode, one->path);
1170
1171                 /*
1172                  * Above, we put the merged content at the merge-base's
1173                  * path.  Now we usually need to delete both a->path and
1174                  * b->path.  However, the rename on each side of the merge
1175                  * could also be involved in a rename/add conflict.  In
1176                  * such cases, we should keep the added file around,
1177                  * resolving the conflict at that path in its favor.
1178                  */
1179                 add = filespec_from_entry(&other, ci->dst_entry1, 2 ^ 1);
1180                 if (add)
1181                         update_file(o, 0, add->sha1, add->mode, a->path);
1182                 else
1183                         remove_file_from_cache(a->path);
1184                 add = filespec_from_entry(&other, ci->dst_entry2, 3 ^ 1);
1185                 if (add)
1186                         update_file(o, 0, add->sha1, add->mode, b->path);
1187                 else
1188                         remove_file_from_cache(b->path);
1189         } else {
1190                 handle_file(o, a, 2, ci);
1191                 handle_file(o, b, 3, ci);
1192         }
1193 }
1194
1195 static void conflict_rename_rename_2to1(struct merge_options *o,
1196                                         struct rename_conflict_info *ci)
1197 {
1198         /* Two files, a & b, were renamed to the same thing, c. */
1199         struct diff_filespec *a = ci->pair1->one;
1200         struct diff_filespec *b = ci->pair2->one;
1201         struct diff_filespec *c1 = ci->pair1->two;
1202         struct diff_filespec *c2 = ci->pair2->two;
1203         char *path = c1->path; /* == c2->path */
1204         struct merge_file_info mfi_c1;
1205         struct merge_file_info mfi_c2;
1206
1207         output(o, 1, "CONFLICT (rename/rename): "
1208                "Rename %s->%s in %s. "
1209                "Rename %s->%s in %s",
1210                a->path, c1->path, ci->branch1,
1211                b->path, c2->path, ci->branch2);
1212
1213         remove_file(o, 1, a->path, would_lose_untracked(a->path));
1214         remove_file(o, 1, b->path, would_lose_untracked(b->path));
1215
1216         mfi_c1 = merge_file_special_markers(o, a, c1, &ci->ren1_other,
1217                                             o->branch1, c1->path,
1218                                             o->branch2, ci->ren1_other.path);
1219         mfi_c2 = merge_file_special_markers(o, b, &ci->ren2_other, c2,
1220                                             o->branch1, ci->ren2_other.path,
1221                                             o->branch2, c2->path);
1222
1223         if (o->call_depth) {
1224                 /*
1225                  * If mfi_c1.clean && mfi_c2.clean, then it might make
1226                  * sense to do a two-way merge of those results.  But, I
1227                  * think in all cases, it makes sense to have the virtual
1228                  * merge base just undo the renames; they can be detected
1229                  * again later for the non-recursive merge.
1230                  */
1231                 remove_file(o, 0, path, 0);
1232                 update_file(o, 0, mfi_c1.sha, mfi_c1.mode, a->path);
1233                 update_file(o, 0, mfi_c2.sha, mfi_c2.mode, b->path);
1234         } else {
1235                 char *new_path1 = unique_path(o, path, ci->branch1);
1236                 char *new_path2 = unique_path(o, path, ci->branch2);
1237                 output(o, 1, "Renaming %s to %s and %s to %s instead",
1238                        a->path, new_path1, b->path, new_path2);
1239                 remove_file(o, 0, path, 0);
1240                 update_file(o, 0, mfi_c1.sha, mfi_c1.mode, new_path1);
1241                 update_file(o, 0, mfi_c2.sha, mfi_c2.mode, new_path2);
1242                 free(new_path2);
1243                 free(new_path1);
1244         }
1245 }
1246
1247 static int process_renames(struct merge_options *o,
1248                            struct string_list *a_renames,
1249                            struct string_list *b_renames)
1250 {
1251         int clean_merge = 1, i, j;
1252         struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
1253         struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
1254         const struct rename *sre;
1255
1256         for (i = 0; i < a_renames->nr; i++) {
1257                 sre = a_renames->items[i].util;
1258                 string_list_insert(&a_by_dst, sre->pair->two->path)->util
1259                         = (void *)sre;
1260         }
1261         for (i = 0; i < b_renames->nr; i++) {
1262                 sre = b_renames->items[i].util;
1263                 string_list_insert(&b_by_dst, sre->pair->two->path)->util
1264                         = (void *)sre;
1265         }
1266
1267         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
1268                 struct string_list *renames1, *renames2Dst;
1269                 struct rename *ren1 = NULL, *ren2 = NULL;
1270                 const char *branch1, *branch2;
1271                 const char *ren1_src, *ren1_dst;
1272                 struct string_list_item *lookup;
1273
1274                 if (i >= a_renames->nr) {
1275                         ren2 = b_renames->items[j++].util;
1276                 } else if (j >= b_renames->nr) {
1277                         ren1 = a_renames->items[i++].util;
1278                 } else {
1279                         int compare = strcmp(a_renames->items[i].string,
1280                                              b_renames->items[j].string);
1281                         if (compare <= 0)
1282                                 ren1 = a_renames->items[i++].util;
1283                         if (compare >= 0)
1284                                 ren2 = b_renames->items[j++].util;
1285                 }
1286
1287                 /* TODO: refactor, so that 1/2 are not needed */
1288                 if (ren1) {
1289                         renames1 = a_renames;
1290                         renames2Dst = &b_by_dst;
1291                         branch1 = o->branch1;
1292                         branch2 = o->branch2;
1293                 } else {
1294                         struct rename *tmp;
1295                         renames1 = b_renames;
1296                         renames2Dst = &a_by_dst;
1297                         branch1 = o->branch2;
1298                         branch2 = o->branch1;
1299                         tmp = ren2;
1300                         ren2 = ren1;
1301                         ren1 = tmp;
1302                 }
1303
1304                 if (ren1->processed)
1305                         continue;
1306                 ren1->processed = 1;
1307                 ren1->dst_entry->processed = 1;
1308                 /* BUG: We should only mark src_entry as processed if we
1309                  * are not dealing with a rename + add-source case.
1310                  */
1311                 ren1->src_entry->processed = 1;
1312
1313                 ren1_src = ren1->pair->one->path;
1314                 ren1_dst = ren1->pair->two->path;
1315
1316                 if (ren2) {
1317                         /* One file renamed on both sides */
1318                         const char *ren2_src = ren2->pair->one->path;
1319                         const char *ren2_dst = ren2->pair->two->path;
1320                         enum rename_type rename_type;
1321                         if (strcmp(ren1_src, ren2_src) != 0)
1322                                 die("ren1_src != ren2_src");
1323                         ren2->dst_entry->processed = 1;
1324                         ren2->processed = 1;
1325                         if (strcmp(ren1_dst, ren2_dst) != 0) {
1326                                 rename_type = RENAME_ONE_FILE_TO_TWO;
1327                                 clean_merge = 0;
1328                         } else {
1329                                 rename_type = RENAME_ONE_FILE_TO_ONE;
1330                                 /* BUG: We should only remove ren1_src in
1331                                  * the base stage (think of rename +
1332                                  * add-source cases).
1333                                  */
1334                                 remove_file(o, 1, ren1_src, 1);
1335                                 update_entry(ren1->dst_entry,
1336                                              ren1->pair->one,
1337                                              ren1->pair->two,
1338                                              ren2->pair->two);
1339                         }
1340                         setup_rename_conflict_info(rename_type,
1341                                                    ren1->pair,
1342                                                    ren2->pair,
1343                                                    branch1,
1344                                                    branch2,
1345                                                    ren1->dst_entry,
1346                                                    ren2->dst_entry,
1347                                                    o,
1348                                                    NULL,
1349                                                    NULL);
1350                 } else if ((lookup = string_list_lookup(renames2Dst, ren1_dst))) {
1351                         /* Two different files renamed to the same thing */
1352                         char *ren2_dst;
1353                         ren2 = lookup->util;
1354                         ren2_dst = ren2->pair->two->path;
1355                         if (strcmp(ren1_dst, ren2_dst) != 0)
1356                                 die("ren1_dst != ren2_dst");
1357
1358                         clean_merge = 0;
1359                         ren2->processed = 1;
1360                         /*
1361                          * BUG: We should only mark src_entry as processed
1362                          * if we are not dealing with a rename + add-source
1363                          * case.
1364                          */
1365                         ren2->src_entry->processed = 1;
1366
1367                         setup_rename_conflict_info(RENAME_TWO_FILES_TO_ONE,
1368                                                    ren1->pair,
1369                                                    ren2->pair,
1370                                                    branch1,
1371                                                    branch2,
1372                                                    ren1->dst_entry,
1373                                                    ren2->dst_entry,
1374                                                    o,
1375                                                    ren1->src_entry,
1376                                                    ren2->src_entry);
1377
1378                 } else {
1379                         /* Renamed in 1, maybe changed in 2 */
1380                         /* we only use sha1 and mode of these */
1381                         struct diff_filespec src_other, dst_other;
1382                         int try_merge;
1383
1384                         /*
1385                          * unpack_trees loads entries from common-commit
1386                          * into stage 1, from head-commit into stage 2, and
1387                          * from merge-commit into stage 3.  We keep track
1388                          * of which side corresponds to the rename.
1389                          */
1390                         int renamed_stage = a_renames == renames1 ? 2 : 3;
1391                         int other_stage =   a_renames == renames1 ? 3 : 2;
1392
1393                         /* BUG: We should only remove ren1_src in the base
1394                          * stage and in other_stage (think of rename +
1395                          * add-source case).
1396                          */
1397                         remove_file(o, 1, ren1_src,
1398                                     renamed_stage == 2 || !was_tracked(ren1_src));
1399
1400                         hashcpy(src_other.sha1, ren1->src_entry->stages[other_stage].sha);
1401                         src_other.mode = ren1->src_entry->stages[other_stage].mode;
1402                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[other_stage].sha);
1403                         dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
1404                         try_merge = 0;
1405
1406                         if (sha_eq(src_other.sha1, null_sha1)) {
1407                                 setup_rename_conflict_info(RENAME_DELETE,
1408                                                            ren1->pair,
1409                                                            NULL,
1410                                                            branch1,
1411                                                            branch2,
1412                                                            ren1->dst_entry,
1413                                                            NULL,
1414                                                            o,
1415                                                            NULL,
1416                                                            NULL);
1417                         } else if ((dst_other.mode == ren1->pair->two->mode) &&
1418                                    sha_eq(dst_other.sha1, ren1->pair->two->sha1)) {
1419                                 /*
1420                                  * Added file on the other side identical to
1421                                  * the file being renamed: clean merge.
1422                                  * Also, there is no need to overwrite the
1423                                  * file already in the working copy, so call
1424                                  * update_file_flags() instead of
1425                                  * update_file().
1426                                  */
1427                                 update_file_flags(o,
1428                                                   ren1->pair->two->sha1,
1429                                                   ren1->pair->two->mode,
1430                                                   ren1_dst,
1431                                                   1, /* update_cache */
1432                                                   0  /* update_wd    */);
1433                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
1434                                 clean_merge = 0;
1435                                 try_merge = 1;
1436                                 output(o, 1, "CONFLICT (rename/add): Rename %s->%s in %s. "
1437                                        "%s added in %s",
1438                                        ren1_src, ren1_dst, branch1,
1439                                        ren1_dst, branch2);
1440                                 if (o->call_depth) {
1441                                         struct merge_file_info mfi;
1442                                         mfi = merge_file(o, ren1_dst, null_sha1, 0,
1443                                                          ren1->pair->two->sha1, ren1->pair->two->mode,
1444                                                          dst_other.sha1, dst_other.mode,
1445                                                          branch1, branch2);
1446                                         output(o, 1, "Adding merged %s", ren1_dst);
1447                                         update_file(o, 0, mfi.sha, mfi.mode, ren1_dst);
1448                                         try_merge = 0;
1449                                 } else {
1450                                         char *new_path = unique_path(o, ren1_dst, branch2);
1451                                         output(o, 1, "Adding as %s instead", new_path);
1452                                         update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
1453                                         free(new_path);
1454                                 }
1455                         } else
1456                                 try_merge = 1;
1457
1458                         if (try_merge) {
1459                                 struct diff_filespec *one, *a, *b;
1460                                 src_other.path = (char *)ren1_src;
1461
1462                                 one = ren1->pair->one;
1463                                 if (a_renames == renames1) {
1464                                         a = ren1->pair->two;
1465                                         b = &src_other;
1466                                 } else {
1467                                         b = ren1->pair->two;
1468                                         a = &src_other;
1469                                 }
1470                                 update_entry(ren1->dst_entry, one, a, b);
1471                                 setup_rename_conflict_info(RENAME_NORMAL,
1472                                                            ren1->pair,
1473                                                            NULL,
1474                                                            branch1,
1475                                                            NULL,
1476                                                            ren1->dst_entry,
1477                                                            NULL,
1478                                                            o,
1479                                                            NULL,
1480                                                            NULL);
1481                         }
1482                 }
1483         }
1484         string_list_clear(&a_by_dst, 0);
1485         string_list_clear(&b_by_dst, 0);
1486
1487         return clean_merge;
1488 }
1489
1490 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1491 {
1492         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1493 }
1494
1495 static int read_sha1_strbuf(const unsigned char *sha1, struct strbuf *dst)
1496 {
1497         void *buf;
1498         enum object_type type;
1499         unsigned long size;
1500         buf = read_sha1_file(sha1, &type, &size);
1501         if (!buf)
1502                 return error("cannot read object %s", sha1_to_hex(sha1));
1503         if (type != OBJ_BLOB) {
1504                 free(buf);
1505                 return error("object %s is not a blob", sha1_to_hex(sha1));
1506         }
1507         strbuf_attach(dst, buf, size, size + 1);
1508         return 0;
1509 }
1510
1511 static int blob_unchanged(const unsigned char *o_sha,
1512                           const unsigned char *a_sha,
1513                           int renormalize, const char *path)
1514 {
1515         struct strbuf o = STRBUF_INIT;
1516         struct strbuf a = STRBUF_INIT;
1517         int ret = 0; /* assume changed for safety */
1518
1519         if (sha_eq(o_sha, a_sha))
1520                 return 1;
1521         if (!renormalize)
1522                 return 0;
1523
1524         assert(o_sha && a_sha);
1525         if (read_sha1_strbuf(o_sha, &o) || read_sha1_strbuf(a_sha, &a))
1526                 goto error_return;
1527         /*
1528          * Note: binary | is used so that both renormalizations are
1529          * performed.  Comparison can be skipped if both files are
1530          * unchanged since their sha1s have already been compared.
1531          */
1532         if (renormalize_buffer(path, o.buf, o.len, &o) |
1533             renormalize_buffer(path, a.buf, o.len, &a))
1534                 ret = (o.len == a.len && !memcmp(o.buf, a.buf, o.len));
1535
1536 error_return:
1537         strbuf_release(&o);
1538         strbuf_release(&a);
1539         return ret;
1540 }
1541
1542 static void handle_modify_delete(struct merge_options *o,
1543                                  const char *path,
1544                                  unsigned char *o_sha, int o_mode,
1545                                  unsigned char *a_sha, int a_mode,
1546                                  unsigned char *b_sha, int b_mode)
1547 {
1548         handle_change_delete(o,
1549                              path,
1550                              o_sha, o_mode,
1551                              a_sha, a_mode,
1552                              b_sha, b_mode,
1553                              "modify", "modified");
1554 }
1555
1556 static int merge_content(struct merge_options *o,
1557                          const char *path,
1558                          unsigned char *o_sha, int o_mode,
1559                          unsigned char *a_sha, int a_mode,
1560                          unsigned char *b_sha, int b_mode,
1561                          struct rename_conflict_info *rename_conflict_info)
1562 {
1563         const char *reason = "content";
1564         const char *path1 = NULL, *path2 = NULL;
1565         struct merge_file_info mfi;
1566         struct diff_filespec one, a, b;
1567         unsigned df_conflict_remains = 0;
1568
1569         if (!o_sha) {
1570                 reason = "add/add";
1571                 o_sha = (unsigned char *)null_sha1;
1572         }
1573         one.path = a.path = b.path = (char *)path;
1574         hashcpy(one.sha1, o_sha);
1575         one.mode = o_mode;
1576         hashcpy(a.sha1, a_sha);
1577         a.mode = a_mode;
1578         hashcpy(b.sha1, b_sha);
1579         b.mode = b_mode;
1580
1581         if (rename_conflict_info) {
1582                 struct diff_filepair *pair1 = rename_conflict_info->pair1;
1583
1584                 path1 = (o->branch1 == rename_conflict_info->branch1) ?
1585                         pair1->two->path : pair1->one->path;
1586                 /* If rename_conflict_info->pair2 != NULL, we are in
1587                  * RENAME_ONE_FILE_TO_ONE case.  Otherwise, we have a
1588                  * normal rename.
1589                  */
1590                 path2 = (rename_conflict_info->pair2 ||
1591                          o->branch2 == rename_conflict_info->branch1) ?
1592                         pair1->two->path : pair1->one->path;
1593
1594                 if (dir_in_way(path, !o->call_depth))
1595                         df_conflict_remains = 1;
1596         }
1597         mfi = merge_file_special_markers(o, &one, &a, &b,
1598                                          o->branch1, path1,
1599                                          o->branch2, path2);
1600
1601         if (mfi.clean && !df_conflict_remains &&
1602             sha_eq(mfi.sha, a_sha) && mfi.mode == a_mode) {
1603                 int path_renamed_outside_HEAD;
1604                 output(o, 3, "Skipped %s (merged same as existing)", path);
1605                 /*
1606                  * The content merge resulted in the same file contents we
1607                  * already had.  We can return early if those file contents
1608                  * are recorded at the correct path (which may not be true
1609                  * if the merge involves a rename).
1610                  */
1611                 path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
1612                 if (!path_renamed_outside_HEAD) {
1613                         add_cacheinfo(mfi.mode, mfi.sha, path,
1614                                       0, (!o->call_depth), 0);
1615                         return mfi.clean;
1616                 }
1617         } else
1618                 output(o, 2, "Auto-merging %s", path);
1619
1620         if (!mfi.clean) {
1621                 if (S_ISGITLINK(mfi.mode))
1622                         reason = "submodule";
1623                 output(o, 1, "CONFLICT (%s): Merge conflict in %s",
1624                                 reason, path);
1625                 if (rename_conflict_info && !df_conflict_remains)
1626                         update_stages(path, &one, &a, &b);
1627         }
1628
1629         if (df_conflict_remains) {
1630                 char *new_path;
1631                 if (o->call_depth) {
1632                         remove_file_from_cache(path);
1633                 } else {
1634                         if (!mfi.clean)
1635                                 update_stages(path, &one, &a, &b);
1636                         else {
1637                                 int file_from_stage2 = was_tracked(path);
1638                                 struct diff_filespec merged;
1639                                 hashcpy(merged.sha1, mfi.sha);
1640                                 merged.mode = mfi.mode;
1641
1642                                 update_stages(path, NULL,
1643                                               file_from_stage2 ? &merged : NULL,
1644                                               file_from_stage2 ? NULL : &merged);
1645                         }
1646
1647                 }
1648                 new_path = unique_path(o, path, rename_conflict_info->branch1);
1649                 output(o, 1, "Adding as %s instead", new_path);
1650                 update_file(o, 0, mfi.sha, mfi.mode, new_path);
1651                 free(new_path);
1652                 mfi.clean = 0;
1653         } else {
1654                 update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
1655         }
1656         return mfi.clean;
1657
1658 }
1659
1660 /* Per entry merge function */
1661 static int process_entry(struct merge_options *o,
1662                          const char *path, struct stage_data *entry)
1663 {
1664         /*
1665         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1666         print_index_entry("\tpath: ", entry);
1667         */
1668         int clean_merge = 1;
1669         int normalize = o->renormalize;
1670         unsigned o_mode = entry->stages[1].mode;
1671         unsigned a_mode = entry->stages[2].mode;
1672         unsigned b_mode = entry->stages[3].mode;
1673         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1674         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1675         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1676
1677         entry->processed = 1;
1678         if (entry->rename_conflict_info) {
1679                 struct rename_conflict_info *conflict_info = entry->rename_conflict_info;
1680                 switch (conflict_info->rename_type) {
1681                 case RENAME_NORMAL:
1682                 case RENAME_ONE_FILE_TO_ONE:
1683                         clean_merge = merge_content(o, path,
1684                                                     o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
1685                                                     conflict_info);
1686                         break;
1687                 case RENAME_DELETE:
1688                         clean_merge = 0;
1689                         conflict_rename_delete(o, conflict_info->pair1,
1690                                                conflict_info->branch1,
1691                                                conflict_info->branch2);
1692                         break;
1693                 case RENAME_ONE_FILE_TO_TWO:
1694                         clean_merge = 0;
1695                         conflict_rename_rename_1to2(o, conflict_info);
1696                         break;
1697                 case RENAME_TWO_FILES_TO_ONE:
1698                         clean_merge = 0;
1699                         conflict_rename_rename_2to1(o, conflict_info);
1700                         break;
1701                 default:
1702                         entry->processed = 0;
1703                         break;
1704                 }
1705         } else if (o_sha && (!a_sha || !b_sha)) {
1706                 /* Case A: Deleted in one */
1707                 if ((!a_sha && !b_sha) ||
1708                     (!b_sha && blob_unchanged(o_sha, a_sha, normalize, path)) ||
1709                     (!a_sha && blob_unchanged(o_sha, b_sha, normalize, path))) {
1710                         /* Deleted in both or deleted in one and
1711                          * unchanged in the other */
1712                         if (a_sha)
1713                                 output(o, 2, "Removing %s", path);
1714                         /* do not touch working file if it did not exist */
1715                         remove_file(o, 1, path, !a_sha);
1716                 } else {
1717                         /* Modify/delete; deleted side may have put a directory in the way */
1718                         clean_merge = 0;
1719                         handle_modify_delete(o, path, o_sha, o_mode,
1720                                              a_sha, a_mode, b_sha, b_mode);
1721                 }
1722         } else if ((!o_sha && a_sha && !b_sha) ||
1723                    (!o_sha && !a_sha && b_sha)) {
1724                 /* Case B: Added in one. */
1725                 /* [nothing|directory] -> ([nothing|directory], file) */
1726
1727                 const char *add_branch;
1728                 const char *other_branch;
1729                 unsigned mode;
1730                 const unsigned char *sha;
1731                 const char *conf;
1732
1733                 if (a_sha) {
1734                         add_branch = o->branch1;
1735                         other_branch = o->branch2;
1736                         mode = a_mode;
1737                         sha = a_sha;
1738                         conf = "file/directory";
1739                 } else {
1740                         add_branch = o->branch2;
1741                         other_branch = o->branch1;
1742                         mode = b_mode;
1743                         sha = b_sha;
1744                         conf = "directory/file";
1745                 }
1746                 if (dir_in_way(path, !o->call_depth)) {
1747                         char *new_path = unique_path(o, path, add_branch);
1748                         clean_merge = 0;
1749                         output(o, 1, "CONFLICT (%s): There is a directory with name %s in %s. "
1750                                "Adding %s as %s",
1751                                conf, path, other_branch, path, new_path);
1752                         if (o->call_depth)
1753                                 remove_file_from_cache(path);
1754                         update_file(o, 0, sha, mode, new_path);
1755                         if (o->call_depth)
1756                                 remove_file_from_cache(path);
1757                         free(new_path);
1758                 } else {
1759                         output(o, 2, "Adding %s", path);
1760                         /* do not overwrite file if already present */
1761                         update_file_flags(o, sha, mode, path, 1, !a_sha);
1762                 }
1763         } else if (a_sha && b_sha) {
1764                 /* Case C: Added in both (check for same permissions) and */
1765                 /* case D: Modified in both, but differently. */
1766                 clean_merge = merge_content(o, path,
1767                                             o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
1768                                             NULL);
1769         } else if (!o_sha && !a_sha && !b_sha) {
1770                 /*
1771                  * this entry was deleted altogether. a_mode == 0 means
1772                  * we had that path and want to actively remove it.
1773                  */
1774                 remove_file(o, 1, path, !a_mode);
1775         } else
1776                 die("Fatal merge failure, shouldn't happen.");
1777
1778         return clean_merge;
1779 }
1780
1781 int merge_trees(struct merge_options *o,
1782                 struct tree *head,
1783                 struct tree *merge,
1784                 struct tree *common,
1785                 struct tree **result)
1786 {
1787         int code, clean;
1788
1789         if (o->subtree_shift) {
1790                 merge = shift_tree_object(head, merge, o->subtree_shift);
1791                 common = shift_tree_object(head, common, o->subtree_shift);
1792         }
1793
1794         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1795                 output(o, 0, "Already up-to-date!");
1796                 *result = head;
1797                 return 1;
1798         }
1799
1800         code = git_merge_trees(o->call_depth, common, head, merge);
1801
1802         if (code != 0) {
1803                 if (show(o, 4) || o->call_depth)
1804                         die("merging of trees %s and %s failed",
1805                             sha1_to_hex(head->object.sha1),
1806                             sha1_to_hex(merge->object.sha1));
1807                 else
1808                         exit(128);
1809         }
1810
1811         if (unmerged_cache()) {
1812                 struct string_list *entries, *re_head, *re_merge;
1813                 int i;
1814                 string_list_clear(&o->current_file_set, 1);
1815                 string_list_clear(&o->current_directory_set, 1);
1816                 get_files_dirs(o, head);
1817                 get_files_dirs(o, merge);
1818
1819                 entries = get_unmerged();
1820                 record_df_conflict_files(o, entries);
1821                 re_head  = get_renames(o, head, common, head, merge, entries);
1822                 re_merge = get_renames(o, merge, common, head, merge, entries);
1823                 clean = process_renames(o, re_head, re_merge);
1824                 for (i = entries->nr-1; 0 <= i; i--) {
1825                         const char *path = entries->items[i].string;
1826                         struct stage_data *e = entries->items[i].util;
1827                         if (!e->processed
1828                                 && !process_entry(o, path, e))
1829                                 clean = 0;
1830                 }
1831                 for (i = 0; i < entries->nr; i++) {
1832                         struct stage_data *e = entries->items[i].util;
1833                         if (!e->processed)
1834                                 die("Unprocessed path??? %s",
1835                                     entries->items[i].string);
1836                 }
1837
1838                 string_list_clear(re_merge, 0);
1839                 string_list_clear(re_head, 0);
1840                 string_list_clear(entries, 1);
1841
1842         }
1843         else
1844                 clean = 1;
1845
1846         if (o->call_depth)
1847                 *result = write_tree_from_memory(o);
1848
1849         return clean;
1850 }
1851
1852 static struct commit_list *reverse_commit_list(struct commit_list *list)
1853 {
1854         struct commit_list *next = NULL, *current, *backup;
1855         for (current = list; current; current = backup) {
1856                 backup = current->next;
1857                 current->next = next;
1858                 next = current;
1859         }
1860         return next;
1861 }
1862
1863 /*
1864  * Merge the commits h1 and h2, return the resulting virtual
1865  * commit object and a flag indicating the cleanness of the merge.
1866  */
1867 int merge_recursive(struct merge_options *o,
1868                     struct commit *h1,
1869                     struct commit *h2,
1870                     struct commit_list *ca,
1871                     struct commit **result)
1872 {
1873         struct commit_list *iter;
1874         struct commit *merged_common_ancestors;
1875         struct tree *mrtree = mrtree;
1876         int clean;
1877
1878         if (show(o, 4)) {
1879                 output(o, 4, "Merging:");
1880                 output_commit_title(o, h1);
1881                 output_commit_title(o, h2);
1882         }
1883
1884         if (!ca) {
1885                 ca = get_merge_bases(h1, h2, 1);
1886                 ca = reverse_commit_list(ca);
1887         }
1888
1889         if (show(o, 5)) {
1890                 output(o, 5, "found %u common ancestor(s):", commit_list_count(ca));
1891                 for (iter = ca; iter; iter = iter->next)
1892                         output_commit_title(o, iter->item);
1893         }
1894
1895         merged_common_ancestors = pop_commit(&ca);
1896         if (merged_common_ancestors == NULL) {
1897                 /* if there is no common ancestor, use an empty tree */
1898                 struct tree *tree;
1899
1900                 tree = lookup_tree(EMPTY_TREE_SHA1_BIN);
1901                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1902         }
1903
1904         for (iter = ca; iter; iter = iter->next) {
1905                 const char *saved_b1, *saved_b2;
1906                 o->call_depth++;
1907                 /*
1908                  * When the merge fails, the result contains files
1909                  * with conflict markers. The cleanness flag is
1910                  * ignored, it was never actually used, as result of
1911                  * merge_trees has always overwritten it: the committed
1912                  * "conflicts" were already resolved.
1913                  */
1914                 discard_cache();
1915                 saved_b1 = o->branch1;
1916                 saved_b2 = o->branch2;
1917                 o->branch1 = "Temporary merge branch 1";
1918                 o->branch2 = "Temporary merge branch 2";
1919                 merge_recursive(o, merged_common_ancestors, iter->item,
1920                                 NULL, &merged_common_ancestors);
1921                 o->branch1 = saved_b1;
1922                 o->branch2 = saved_b2;
1923                 o->call_depth--;
1924
1925                 if (!merged_common_ancestors)
1926                         die("merge returned no commit");
1927         }
1928
1929         discard_cache();
1930         if (!o->call_depth)
1931                 read_cache();
1932
1933         o->ancestor = "merged common ancestors";
1934         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
1935                             &mrtree);
1936
1937         if (o->call_depth) {
1938                 *result = make_virtual_commit(mrtree, "merged tree");
1939                 commit_list_insert(h1, &(*result)->parents);
1940                 commit_list_insert(h2, &(*result)->parents->next);
1941         }
1942         flush_output(o);
1943         if (show(o, 2))
1944                 diff_warn_rename_limit("merge.renamelimit",
1945                                        o->needed_rename_limit, 0);
1946         return clean;
1947 }
1948
1949 static struct commit *get_ref(const unsigned char *sha1, const char *name)
1950 {
1951         struct object *object;
1952
1953         object = deref_tag(parse_object(sha1), name, strlen(name));
1954         if (!object)
1955                 return NULL;
1956         if (object->type == OBJ_TREE)
1957                 return make_virtual_commit((struct tree*)object, name);
1958         if (object->type != OBJ_COMMIT)
1959                 return NULL;
1960         if (parse_commit((struct commit *)object))
1961                 return NULL;
1962         return (struct commit *)object;
1963 }
1964
1965 int merge_recursive_generic(struct merge_options *o,
1966                             const unsigned char *head,
1967                             const unsigned char *merge,
1968                             int num_base_list,
1969                             const unsigned char **base_list,
1970                             struct commit **result)
1971 {
1972         int clean, index_fd;
1973         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1974         struct commit *head_commit = get_ref(head, o->branch1);
1975         struct commit *next_commit = get_ref(merge, o->branch2);
1976         struct commit_list *ca = NULL;
1977
1978         if (base_list) {
1979                 int i;
1980                 for (i = 0; i < num_base_list; ++i) {
1981                         struct commit *base;
1982                         if (!(base = get_ref(base_list[i], sha1_to_hex(base_list[i]))))
1983                                 return error("Could not parse object '%s'",
1984                                         sha1_to_hex(base_list[i]));
1985                         commit_list_insert(base, &ca);
1986                 }
1987         }
1988
1989         index_fd = hold_locked_index(lock, 1);
1990         clean = merge_recursive(o, head_commit, next_commit, ca,
1991                         result);
1992         if (active_cache_changed &&
1993                         (write_cache(index_fd, active_cache, active_nr) ||
1994                          commit_locked_index(lock)))
1995                 return error("Unable to write index.");
1996
1997         return clean ? 0 : 1;
1998 }
1999
2000 static int merge_recursive_config(const char *var, const char *value, void *cb)
2001 {
2002         struct merge_options *o = cb;
2003         if (!strcmp(var, "merge.verbosity")) {
2004                 o->verbosity = git_config_int(var, value);
2005                 return 0;
2006         }
2007         if (!strcmp(var, "diff.renamelimit")) {
2008                 o->diff_rename_limit = git_config_int(var, value);
2009                 return 0;
2010         }
2011         if (!strcmp(var, "merge.renamelimit")) {
2012                 o->merge_rename_limit = git_config_int(var, value);
2013                 return 0;
2014         }
2015         return git_xmerge_config(var, value, cb);
2016 }
2017
2018 void init_merge_options(struct merge_options *o)
2019 {
2020         memset(o, 0, sizeof(struct merge_options));
2021         o->verbosity = 2;
2022         o->buffer_output = 1;
2023         o->diff_rename_limit = -1;
2024         o->merge_rename_limit = -1;
2025         o->renormalize = 0;
2026         git_config(merge_recursive_config, o);
2027         if (getenv("GIT_MERGE_VERBOSITY"))
2028                 o->verbosity =
2029                         strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
2030         if (o->verbosity >= 5)
2031                 o->buffer_output = 0;
2032         strbuf_init(&o->obuf, 0);
2033         memset(&o->current_file_set, 0, sizeof(struct string_list));
2034         o->current_file_set.strdup_strings = 1;
2035         memset(&o->current_directory_set, 0, sizeof(struct string_list));
2036         o->current_directory_set.strdup_strings = 1;
2037         memset(&o->df_conflict_file_set, 0, sizeof(struct string_list));
2038         o->df_conflict_file_set.strdup_strings = 1;
2039 }
2040
2041 int parse_merge_opt(struct merge_options *o, const char *s)
2042 {
2043         if (!s || !*s)
2044                 return -1;
2045         if (!strcmp(s, "ours"))
2046                 o->recursive_variant = MERGE_RECURSIVE_OURS;
2047         else if (!strcmp(s, "theirs"))
2048                 o->recursive_variant = MERGE_RECURSIVE_THEIRS;
2049         else if (!strcmp(s, "subtree"))
2050                 o->subtree_shift = "";
2051         else if (!prefixcmp(s, "subtree="))
2052                 o->subtree_shift = s + strlen("subtree=");
2053         else if (!strcmp(s, "patience"))
2054                 o->xdl_opts = DIFF_WITH_ALG(o, PATIENCE_DIFF);
2055         else if (!strcmp(s, "histogram"))
2056                 o->xdl_opts = DIFF_WITH_ALG(o, HISTOGRAM_DIFF);
2057         else if (!strcmp(s, "ignore-space-change"))
2058                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_CHANGE;
2059         else if (!strcmp(s, "ignore-all-space"))
2060                 o->xdl_opts |= XDF_IGNORE_WHITESPACE;
2061         else if (!strcmp(s, "ignore-space-at-eol"))
2062                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_AT_EOL;
2063         else if (!strcmp(s, "renormalize"))
2064                 o->renormalize = 1;
2065         else if (!strcmp(s, "no-renormalize"))
2066                 o->renormalize = 0;
2067         else if (!prefixcmp(s, "rename-threshold=")) {
2068                 const char *score = s + strlen("rename-threshold=");
2069                 if ((o->rename_score = parse_rename_score(&score)) == -1 || *score != 0)
2070                         return -1;
2071         }
2072         else
2073                 return -1;
2074         return 0;
2075 }