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 "cache.h"
   7 #include "advice.h"
   8 #include "lockfile.h"
   9 #include "cache-tree.h"
  10 #include "commit.h"
  11 #include "blob.h"
  12 #include "builtin.h"
  13 #include "tree-walk.h"
  14 #include "diff.h"
  15 #include "diffcore.h"
  16 #include "tag.h"
  17 #include "unpack-trees.h"
  18 #include "string-list.h"
  19 #include "xdiff-interface.h"
  20 #include "ll-merge.h"
  21 #include "attr.h"
  22 #include "merge-recursive.h"
  23 #include "dir.h"
  24 #include "submodule.h"
  25
  26 static struct tree *shift_tree_object(struct tree *one, struct tree *two,
  27                                       const char *subtree_shift)
  28 {
  29         struct object_id shifted;
  30
  31         if (!*subtree_shift) {
  32                 shift_tree(&one->object.oid, &two->object.oid, &shifted, 0);
  33         } else {
  34                 shift_tree_by(&one->object.oid, &two->object.oid, &shifted,
  35                               subtree_shift);
  36         }
  37         if (!oidcmp(&two->object.oid, &shifted))
  38                 return two;
  39         return lookup_tree(shifted.hash);
  40 }
  41
  42 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  43 {
  44         struct commit *commit = alloc_commit_node();
  45
  46         set_merge_remote_desc(commit, comment, (struct object *)commit);
  47         commit->tree = tree;
  48         commit->object.parsed = 1;
  49         return commit;
  50 }
  51
  52 /*
  53  * Since we use get_tree_entry(), which does not put the read object into
  54  * the object pool, we cannot rely on a == b.
  55  */
  56 static int sha_eq(const unsigned char *a, const unsigned char *b)
  57 {
  58         if (!a && !b)
  59                 return 2;
  60         return a && b && hashcmp(a, b) == 0;
  61 }
  62
  63 enum rename_type {
  64         RENAME_NORMAL = 0,
  65         RENAME_DELETE,
  66         RENAME_ONE_FILE_TO_ONE,
  67         RENAME_ONE_FILE_TO_TWO,
  68         RENAME_TWO_FILES_TO_ONE
  69 };
  70
  71 struct rename_conflict_info {
  72         enum rename_type rename_type;
  73         struct diff_filepair *pair1;
  74         struct diff_filepair *pair2;
  75         const char *branch1;
  76         const char *branch2;
  77         struct stage_data *dst_entry1;
  78         struct stage_data *dst_entry2;
  79         struct diff_filespec ren1_other;
  80         struct diff_filespec ren2_other;
  81 };
  82
  83 /*
  84  * Since we want to write the index eventually, we cannot reuse the index
  85  * for these (temporary) data.
  86  */
  87 struct stage_data {
  88         struct {
  89                 unsigned mode;
  90                 unsigned char sha[20];
  91         } stages[4];
  92         struct rename_conflict_info *rename_conflict_info;
  93         unsigned processed:1;
  94 };
  95
  96 static inline void setup_rename_conflict_info(enum rename_type rename_type,
  97                                               struct diff_filepair *pair1,
  98                                               struct diff_filepair *pair2,
  99                                               const char *branch1,
 100                                               const char *branch2,
 101                                               struct stage_data *dst_entry1,
 102                                               struct stage_data *dst_entry2,
 103                                               struct merge_options *o,
 104                                               struct stage_data *src_entry1,
 105                                               struct stage_data *src_entry2)
 106 {
 107         struct rename_conflict_info *ci = xcalloc(1, sizeof(struct rename_conflict_info));
 108         ci->rename_type = rename_type;
 109         ci->pair1 = pair1;
 110         ci->branch1 = branch1;
 111         ci->branch2 = branch2;
 112
 113         ci->dst_entry1 = dst_entry1;
 114         dst_entry1->rename_conflict_info = ci;
 115         dst_entry1->processed = 0;
 116
 117         assert(!pair2 == !dst_entry2);
 118         if (dst_entry2) {
 119                 ci->dst_entry2 = dst_entry2;
 120                 ci->pair2 = pair2;
 121                 dst_entry2->rename_conflict_info = ci;
 122         }
 123
 124         if (rename_type == RENAME_TWO_FILES_TO_ONE) {
 125                 /*
 126                  * For each rename, there could have been
 127                  * modifications on the side of history where that
 128                  * file was not renamed.
 129                  */
 130                 int ostage1 = o->branch1 == branch1 ? 3 : 2;
 131                 int ostage2 = ostage1 ^ 1;
 132
 133                 ci->ren1_other.path = pair1->one->path;
 134                 hashcpy(ci->ren1_other.sha1, src_entry1->stages[ostage1].sha);
 135                 ci->ren1_other.mode = src_entry1->stages[ostage1].mode;
 136
 137                 ci->ren2_other.path = pair2->one->path;
 138                 hashcpy(ci->ren2_other.sha1, src_entry2->stages[ostage2].sha);
 139                 ci->ren2_other.mode = src_entry2->stages[ostage2].mode;
 140         }
 141 }
 142
 143 static int show(struct merge_options *o, int v)
 144 {
 145         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
 146 }
 147
 148 static void flush_output(struct merge_options *o)
 149 {
 150         if (o->obuf.len) {
 151                 fputs(o->obuf.buf, stdout);
 152                 strbuf_reset(&o->obuf);
 153         }
 154 }
 155
 156 __attribute__((format (printf, 3, 4)))
 157 static void output(struct merge_options *o, int v, const char *fmt, ...)
 158 {
 159         va_list ap;
 160
 161         if (!show(o, v))
 162                 return;
 163
 164         strbuf_addchars(&o->obuf, ' ', o->call_depth * 2);
 165
 166         va_start(ap, fmt);
 167         strbuf_vaddf(&o->obuf, fmt, ap);
 168         va_end(ap);
 169
 170         strbuf_addch(&o->obuf, '\n');
 171         if (!o->buffer_output)
 172                 flush_output(o);
 173 }
 174
 175 static void output_commit_title(struct merge_options *o, struct commit *commit)
 176 {
 177         int i;
 178         flush_output(o);
 179         for (i = o->call_depth; i--;)
 180                 fputs("  ", stdout);
 181         if (commit->util)
 182                 printf("virtual %s\n", merge_remote_util(commit)->name);
 183         else {
 184                 printf("%s ", find_unique_abbrev(commit->object.oid.hash, DEFAULT_ABBREV));
 185                 if (parse_commit(commit) != 0)
 186                         printf(_("(bad commit)\n"));
 187                 else {
 188                         const char *title;
 189                         const char *msg = get_commit_buffer(commit, NULL);
 190                         int len = find_commit_subject(msg, &title);
 191                         if (len)
 192                                 printf("%.*s\n", len, title);
 193                         unuse_commit_buffer(commit, msg);
 194                 }
 195         }
 196 }
 197
 198 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 199                 const char *path, int stage, int refresh, int options)
 200 {
 201         struct cache_entry *ce;
 202         int ret;
 203
 204         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, 0);
 205         if (!ce)
 206                 return error(_("addinfo_cache failed for path '%s'"), path);
 207
 208         ret = add_cache_entry(ce, options);
 209         if (refresh) {
 210                 struct cache_entry *nce;
 211
 212                 nce = refresh_cache_entry(ce, CE_MATCH_REFRESH | CE_MATCH_IGNORE_MISSING);
 213                 if (nce != ce)
 214                         ret = add_cache_entry(nce, options);
 215         }
 216         return ret;
 217 }
 218
 219 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 220 {
 221         parse_tree(tree);
 222         init_tree_desc(desc, tree->buffer, tree->size);
 223 }
 224
 225 static int git_merge_trees(int index_only,
 226                            struct tree *common,
 227                            struct tree *head,
 228                            struct tree *merge)
 229 {
 230         int rc;
 231         struct tree_desc t[3];
 232         struct unpack_trees_options opts;
 233
 234         memset(&opts, 0, sizeof(opts));
 235         if (index_only)
 236                 opts.index_only = 1;
 237         else
 238                 opts.update = 1;
 239         opts.merge = 1;
 240         opts.head_idx = 2;
 241         opts.fn = threeway_merge;
 242         opts.src_index = &the_index;
 243         opts.dst_index = &the_index;
 244         setup_unpack_trees_porcelain(&opts, "merge");
 245
 246         init_tree_desc_from_tree(t+0, common);
 247         init_tree_desc_from_tree(t+1, head);
 248         init_tree_desc_from_tree(t+2, merge);
 249
 250         rc = unpack_trees(3, t, &opts);
 251         cache_tree_free(&active_cache_tree);
 252         return rc;
 253 }
 254
 255 struct tree *write_tree_from_memory(struct merge_options *o)
 256 {
 257         struct tree *result = NULL;
 258
 259         if (unmerged_cache()) {
 260                 int i;
 261                 fprintf(stderr, "BUG: There are unmerged index entries:\n");
 262                 for (i = 0; i < active_nr; i++) {
 263                         const struct cache_entry *ce = active_cache[i];
 264                         if (ce_stage(ce))
 265                                 fprintf(stderr, "BUG: %d %.*s\n", ce_stage(ce),
 266                                         (int)ce_namelen(ce), ce->name);
 267                 }
 268                 die("Bug in merge-recursive.c");
 269         }
 270
 271         if (!active_cache_tree)
 272                 active_cache_tree = cache_tree();
 273
 274         if (!cache_tree_fully_valid(active_cache_tree) &&
 275             cache_tree_update(&the_index, 0) < 0)
 276                 die(_("error building trees"));
 277
 278         result = lookup_tree(active_cache_tree->sha1);
 279
 280         return result;
 281 }
 282
 283 static int save_files_dirs(const unsigned char *sha1,
 284                 struct strbuf *base, const char *path,
 285                 unsigned int mode, int stage, void *context)
 286 {
 287         int baselen = base->len;
 288         struct merge_options *o = context;
 289
 290         strbuf_addstr(base, path);
 291
 292         if (S_ISDIR(mode))
 293                 string_list_insert(&o->current_directory_set, base->buf);
 294         else
 295                 string_list_insert(&o->current_file_set, base->buf);
 296
 297         strbuf_setlen(base, baselen);
 298         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
 299 }
 300
 301 static int get_files_dirs(struct merge_options *o, struct tree *tree)
 302 {
 303         int n;
 304         struct pathspec match_all;
 305         memset(&match_all, 0, sizeof(match_all));
 306         if (read_tree_recursive(tree, "", 0, 0, &match_all, save_files_dirs, o))
 307                 return 0;
 308         n = o->current_file_set.nr + o->current_directory_set.nr;
 309         return n;
 310 }
 311
 312 /*
 313  * Returns an index_entry instance which doesn't have to correspond to
 314  * a real cache entry in Git's index.
 315  */
 316 static struct stage_data *insert_stage_data(const char *path,
 317                 struct tree *o, struct tree *a, struct tree *b,
 318                 struct string_list *entries)
 319 {
 320         struct string_list_item *item;
 321         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 322         get_tree_entry(o->object.oid.hash, path,
 323                         e->stages[1].sha, &e->stages[1].mode);
 324         get_tree_entry(a->object.oid.hash, path,
 325                         e->stages[2].sha, &e->stages[2].mode);
 326         get_tree_entry(b->object.oid.hash, path,
 327                         e->stages[3].sha, &e->stages[3].mode);
 328         item = string_list_insert(entries, path);
 329         item->util = e;
 330         return e;
 331 }
 332
 333 /*
 334  * Create a dictionary mapping file names to stage_data objects. The
 335  * dictionary contains one entry for every path with a non-zero stage entry.
 336  */
 337 static struct string_list *get_unmerged(void)
 338 {
 339         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
 340         int i;
 341
 342         unmerged->strdup_strings = 1;
 343
 344         for (i = 0; i < active_nr; i++) {
 345                 struct string_list_item *item;
 346                 struct stage_data *e;
 347                 const struct cache_entry *ce = active_cache[i];
 348                 if (!ce_stage(ce))
 349                         continue;
 350
 351                 item = string_list_lookup(unmerged, ce->name);
 352                 if (!item) {
 353                         item = string_list_insert(unmerged, ce->name);
 354                         item->util = xcalloc(1, sizeof(struct stage_data));
 355                 }
 356                 e = item->util;
 357                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
 358                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 359         }
 360
 361         return unmerged;
 362 }
 363
 364 static int string_list_df_name_compare(const void *a, const void *b)
 365 {
 366         const struct string_list_item *one = a;
 367         const struct string_list_item *two = b;
 368         int onelen = strlen(one->string);
 369         int twolen = strlen(two->string);
 370         /*
 371          * Here we only care that entries for D/F conflicts are
 372          * adjacent, in particular with the file of the D/F conflict
 373          * appearing before files below the corresponding directory.
 374          * The order of the rest of the list is irrelevant for us.
 375          *
 376          * To achieve this, we sort with df_name_compare and provide
 377          * the mode S_IFDIR so that D/F conflicts will sort correctly.
 378          * We use the mode S_IFDIR for everything else for simplicity,
 379          * since in other cases any changes in their order due to
 380          * sorting cause no problems for us.
 381          */
 382         int cmp = df_name_compare(one->string, onelen, S_IFDIR,
 383                                   two->string, twolen, S_IFDIR);
 384         /*
 385          * Now that 'foo' and 'foo/bar' compare equal, we have to make sure
 386          * that 'foo' comes before 'foo/bar'.
 387          */
 388         if (cmp)
 389                 return cmp;
 390         return onelen - twolen;
 391 }
 392
 393 static void record_df_conflict_files(struct merge_options *o,
 394                                      struct string_list *entries)
 395 {
 396         /* If there is a D/F conflict and the file for such a conflict
 397          * currently exist in the working tree, we want to allow it to be
 398          * removed to make room for the corresponding directory if needed.
 399          * The files underneath the directories of such D/F conflicts will
 400          * be processed before the corresponding file involved in the D/F
 401          * conflict.  If the D/F directory ends up being removed by the
 402          * merge, then we won't have to touch the D/F file.  If the D/F
 403          * directory needs to be written to the working copy, then the D/F
 404          * file will simply be removed (in make_room_for_path()) to make
 405          * room for the necessary paths.  Note that if both the directory
 406          * and the file need to be present, then the D/F file will be
 407          * reinstated with a new unique name at the time it is processed.
 408          */
 409         struct string_list df_sorted_entries;
 410         const char *last_file = NULL;
 411         int last_len = 0;
 412         int i;
 413
 414         /*
 415          * If we're merging merge-bases, we don't want to bother with
 416          * any working directory changes.
 417          */
 418         if (o->call_depth)
 419                 return;
 420
 421         /* Ensure D/F conflicts are adjacent in the entries list. */
 422         memset(&df_sorted_entries, 0, sizeof(struct string_list));
 423         for (i = 0; i < entries->nr; i++) {
 424                 struct string_list_item *next = &entries->items[i];
 425                 string_list_append(&df_sorted_entries, next->string)->util =
 426                                    next->util;
 427         }
 428         qsort(df_sorted_entries.items, entries->nr, sizeof(*entries->items),
 429               string_list_df_name_compare);
 430
 431         string_list_clear(&o->df_conflict_file_set, 1);
 432         for (i = 0; i < df_sorted_entries.nr; i++) {
 433                 const char *path = df_sorted_entries.items[i].string;
 434                 int len = strlen(path);
 435                 struct stage_data *e = df_sorted_entries.items[i].util;
 436
 437                 /*
 438                  * Check if last_file & path correspond to a D/F conflict;
 439                  * i.e. whether path is last_file+'/'+<something>.
 440                  * If so, record that it's okay to remove last_file to make
 441                  * room for path and friends if needed.
 442                  */
 443                 if (last_file &&
 444                     len > last_len &&
 445                     memcmp(path, last_file, last_len) == 0 &&
 446                     path[last_len] == '/') {
 447                         string_list_insert(&o->df_conflict_file_set, last_file);
 448                 }
 449
 450                 /*
 451                  * Determine whether path could exist as a file in the
 452                  * working directory as a possible D/F conflict.  This
 453                  * will only occur when it exists in stage 2 as a
 454                  * file.
 455                  */
 456                 if (S_ISREG(e->stages[2].mode) || S_ISLNK(e->stages[2].mode)) {
 457                         last_file = path;
 458                         last_len = len;
 459                 } else {
 460                         last_file = NULL;
 461                 }
 462         }
 463         string_list_clear(&df_sorted_entries, 0);
 464 }
 465
 466 struct rename {
 467         struct diff_filepair *pair;
 468         struct stage_data *src_entry;
 469         struct stage_data *dst_entry;
 470         unsigned processed:1;
 471 };
 472
 473 /*
 474  * Get information of all renames which occurred between 'o_tree' and
 475  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 476  * 'b_tree') to be able to associate the correct cache entries with
 477  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 478  */
 479 static struct string_list *get_renames(struct merge_options *o,
 480                                        struct tree *tree,
 481                                        struct tree *o_tree,
 482                                        struct tree *a_tree,
 483                                        struct tree *b_tree,
 484                                        struct string_list *entries)
 485 {
 486         int i;
 487         struct string_list *renames;
 488         struct diff_options opts;
 489
 490         renames = xcalloc(1, sizeof(struct string_list));
 491         if (!o->detect_rename)
 492                 return renames;
 493
 494         diff_setup(&opts);
 495         DIFF_OPT_SET(&opts, RECURSIVE);
 496         DIFF_OPT_CLR(&opts, RENAME_EMPTY);
 497         opts.detect_rename = DIFF_DETECT_RENAME;
 498         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 499                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 500                             1000;
 501         opts.rename_score = o->rename_score;
 502         opts.show_rename_progress = o->show_rename_progress;
 503         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 504         diff_setup_done(&opts);
 505         diff_tree_sha1(o_tree->object.oid.hash, tree->object.oid.hash, "", &opts);
 506         diffcore_std(&opts);
 507         if (opts.needed_rename_limit > o->needed_rename_limit)
 508                 o->needed_rename_limit = opts.needed_rename_limit;
 509         for (i = 0; i < diff_queued_diff.nr; ++i) {
 510                 struct string_list_item *item;
 511                 struct rename *re;
 512                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 513                 if (pair->status != 'R') {
 514                         diff_free_filepair(pair);
 515                         continue;
 516                 }
 517                 re = xmalloc(sizeof(*re));
 518                 re->processed = 0;
 519                 re->pair = pair;
 520                 item = string_list_lookup(entries, re->pair->one->path);
 521                 if (!item)
 522                         re->src_entry = insert_stage_data(re->pair->one->path,
 523                                         o_tree, a_tree, b_tree, entries);
 524                 else
 525                         re->src_entry = item->util;
 526
 527                 item = string_list_lookup(entries, re->pair->two->path);
 528                 if (!item)
 529                         re->dst_entry = insert_stage_data(re->pair->two->path,
 530                                         o_tree, a_tree, b_tree, entries);
 531                 else
 532                         re->dst_entry = item->util;
 533                 item = string_list_insert(renames, pair->one->path);
 534                 item->util = re;
 535         }
 536         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 537         diff_queued_diff.nr = 0;
 538         diff_flush(&opts);
 539         return renames;
 540 }
 541
 542 static int update_stages(const char *path, const struct diff_filespec *o,
 543                          const struct diff_filespec *a,
 544                          const struct diff_filespec *b)
 545 {
 546
 547         /*
 548          * NOTE: It is usually a bad idea to call update_stages on a path
 549          * before calling update_file on that same path, since it can
 550          * sometimes lead to spurious "refusing to lose untracked file..."
 551          * messages from update_file (via make_room_for path via
 552          * would_lose_untracked).  Instead, reverse the order of the calls
 553          * (executing update_file first and then update_stages).
 554          */
 555         int clear = 1;
 556         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_SKIP_DFCHECK;
 557         if (clear)
 558                 if (remove_file_from_cache(path))
 559                         return -1;
 560         if (o)
 561                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 562                         return -1;
 563         if (a)
 564                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 565                         return -1;
 566         if (b)
 567                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 568                         return -1;
 569         return 0;
 570 }
 571
 572 static void update_entry(struct stage_data *entry,
 573                          struct diff_filespec *o,
 574                          struct diff_filespec *a,
 575                          struct diff_filespec *b)
 576 {
 577         entry->processed = 0;
 578         entry->stages[1].mode = o->mode;
 579         entry->stages[2].mode = a->mode;
 580         entry->stages[3].mode = b->mode;
 581         hashcpy(entry->stages[1].sha, o->sha1);
 582         hashcpy(entry->stages[2].sha, a->sha1);
 583         hashcpy(entry->stages[3].sha, b->sha1);
 584 }
 585
 586 static int remove_file(struct merge_options *o, int clean,
 587                        const char *path, int no_wd)
 588 {
 589         int update_cache = o->call_depth || clean;
 590         int update_working_directory = !o->call_depth && !no_wd;
 591
 592         if (update_cache) {
 593                 if (remove_file_from_cache(path))
 594                         return -1;
 595         }
 596         if (update_working_directory) {
 597                 if (ignore_case) {
 598                         struct cache_entry *ce;
 599                         ce = cache_file_exists(path, strlen(path), ignore_case);
 600                         if (ce && ce_stage(ce) == 0)
 601                                 return 0;
 602                 }
 603                 if (remove_path(path))
 604                         return -1;
 605         }
 606         return 0;
 607 }
 608
 609 /* add a string to a strbuf, but converting "/" to "_" */
 610 static void add_flattened_path(struct strbuf *out, const char *s)
 611 {
 612         size_t i = out->len;
 613         strbuf_addstr(out, s);
 614         for (; i < out->len; i++)
 615                 if (out->buf[i] == '/')
 616                         out->buf[i] = '_';
 617 }
 618
 619 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
 620 {
 621         struct strbuf newpath = STRBUF_INIT;
 622         int suffix = 0;
 623         size_t base_len;
 624
 625         strbuf_addf(&newpath, "%s~", path);
 626         add_flattened_path(&newpath, branch);
 627
 628         base_len = newpath.len;
 629         while (string_list_has_string(&o->current_file_set, newpath.buf) ||
 630                string_list_has_string(&o->current_directory_set, newpath.buf) ||
 631                (!o->call_depth && file_exists(newpath.buf))) {
 632                 strbuf_setlen(&newpath, base_len);
 633                 strbuf_addf(&newpath, "_%d", suffix++);
 634         }
 635
 636         string_list_insert(&o->current_file_set, newpath.buf);
 637         return strbuf_detach(&newpath, NULL);
 638 }
 639
 640 static int dir_in_way(const char *path, int check_working_copy)
 641 {
 642         int pos;
 643         struct strbuf dirpath = STRBUF_INIT;
 644         struct stat st;
 645
 646         strbuf_addstr(&dirpath, path);
 647         strbuf_addch(&dirpath, '/');
 648
 649         pos = cache_name_pos(dirpath.buf, dirpath.len);
 650
 651         if (pos < 0)
 652                 pos = -1 - pos;
 653         if (pos < active_nr &&
 654             !strncmp(dirpath.buf, active_cache[pos]->name, dirpath.len)) {
 655                 strbuf_release(&dirpath);
 656                 return 1;
 657         }
 658
 659         strbuf_release(&dirpath);
 660         return check_working_copy && !lstat(path, &st) && S_ISDIR(st.st_mode);
 661 }
 662
 663 static int was_tracked(const char *path)
 664 {
 665         int pos = cache_name_pos(path, strlen(path));
 666
 667         if (pos < 0)
 668                 pos = -1 - pos;
 669         while (pos < active_nr &&
 670                !strcmp(path, active_cache[pos]->name)) {
 671                 /*
 672                  * If stage #0, it is definitely tracked.
 673                  * If it has stage #2 then it was tracked
 674                  * before this merge started.  All other
 675                  * cases the path was not tracked.
 676                  */
 677                 switch (ce_stage(active_cache[pos])) {
 678                 case 0:
 679                 case 2:
 680                         return 1;
 681                 }
 682                 pos++;
 683         }
 684         return 0;
 685 }
 686
 687 static int would_lose_untracked(const char *path)
 688 {
 689         return !was_tracked(path) && file_exists(path);
 690 }
 691
 692 static int make_room_for_path(struct merge_options *o, const char *path)
 693 {
 694         int status, i;
 695         const char *msg = _("failed to create path '%s'%s");
 696
 697         /* Unlink any D/F conflict files that are in the way */
 698         for (i = 0; i < o->df_conflict_file_set.nr; i++) {
 699                 const char *df_path = o->df_conflict_file_set.items[i].string;
 700                 size_t pathlen = strlen(path);
 701                 size_t df_pathlen = strlen(df_path);
 702                 if (df_pathlen < pathlen &&
 703                     path[df_pathlen] == '/' &&
 704                     strncmp(path, df_path, df_pathlen) == 0) {
 705                         output(o, 3,
 706                                _("Removing %s to make room for subdirectory\n"),
 707                                df_path);
 708                         unlink(df_path);
 709                         unsorted_string_list_delete_item(&o->df_conflict_file_set,
 710                                                          i, 0);
 711                         break;
 712                 }
 713         }
 714
 715         /* Make sure leading directories are created */
 716         status = safe_create_leading_directories_const(path);
 717         if (status) {
 718                 if (status == SCLD_EXISTS) {
 719                         /* something else exists */
 720                         error(msg, path, _(": perhaps a D/F conflict?"));
 721                         return -1;
 722                 }
 723                 die(msg, path, "");
 724         }
 725
 726         /*
 727          * Do not unlink a file in the work tree if we are not
 728          * tracking it.
 729          */
 730         if (would_lose_untracked(path))
 731                 return error(_("refusing to lose untracked file at '%s'"),
 732                              path);
 733
 734         /* Successful unlink is good.. */
 735         if (!unlink(path))
 736                 return 0;
 737         /* .. and so is no existing file */
 738         if (errno == ENOENT)
 739                 return 0;
 740         /* .. but not some other error (who really cares what?) */
 741         return error(msg, path, _(": perhaps a D/F conflict?"));
 742 }
 743
 744 static void update_file_flags(struct merge_options *o,
 745                               const unsigned char *sha,
 746                               unsigned mode,
 747                               const char *path,
 748                               int update_cache,
 749                               int update_wd)
 750 {
 751         if (o->call_depth)
 752                 update_wd = 0;
 753
 754         if (update_wd) {
 755                 enum object_type type;
 756                 void *buf;
 757                 unsigned long size;
 758
 759                 if (S_ISGITLINK(mode)) {
 760                         /*
 761                          * We may later decide to recursively descend into
 762                          * the submodule directory and update its index
 763                          * and/or work tree, but we do not do that now.
 764                          */
 765                         update_wd = 0;
 766                         goto update_index;
 767                 }
 768
 769                 buf = read_sha1_file(sha, &type, &size);
 770                 if (!buf)
 771                         die(_("cannot read object %s '%s'"), sha1_to_hex(sha), path);
 772                 if (type != OBJ_BLOB)
 773                         die(_("blob expected for %s '%s'"), sha1_to_hex(sha), path);
 774                 if (S_ISREG(mode)) {
 775                         struct strbuf strbuf = STRBUF_INIT;
 776                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
 777                                 free(buf);
 778                                 size = strbuf.len;
 779                                 buf = strbuf_detach(&strbuf, NULL);
 780                         }
 781                 }
 782
 783                 if (make_room_for_path(o, path) < 0) {
 784                         update_wd = 0;
 785                         free(buf);
 786                         goto update_index;
 787                 }
 788                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 789                         int fd;
 790                         if (mode & 0100)
 791                                 mode = 0777;
 792                         else
 793                                 mode = 0666;
 794                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 795                         if (fd < 0)
 796                                 die_errno(_("failed to open '%s'"), path);
 797                         write_in_full(fd, buf, size);
 798                         close(fd);
 799                 } else if (S_ISLNK(mode)) {
 800                         char *lnk = xmemdupz(buf, size);
 801                         safe_create_leading_directories_const(path);
 802                         unlink(path);
 803                         if (symlink(lnk, path))
 804                                 die_errno(_("failed to symlink '%s'"), path);
 805                         free(lnk);
 806                 } else
 807                         die(_("do not know what to do with %06o %s '%s'"),
 808                             mode, sha1_to_hex(sha), path);
 809                 free(buf);
 810         }
 811  update_index:
 812         if (update_cache)
 813                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 814 }
 815
 816 static void update_file(struct merge_options *o,
 817                         int clean,
 818                         const unsigned char *sha,
 819                         unsigned mode,
 820                         const char *path)
 821 {
 822         update_file_flags(o, sha, mode, path, o->call_depth || clean, !o->call_depth);
 823 }
 824
 825 /* Low level file merging, update and removal */
 826
 827 struct merge_file_info {
 828         unsigned char sha[20];
 829         unsigned mode;
 830         unsigned clean:1,
 831                  merge:1;
 832 };
 833
 834 static int merge_3way(struct merge_options *o,
 835                       mmbuffer_t *result_buf,
 836                       const struct diff_filespec *one,
 837                       const struct diff_filespec *a,
 838                       const struct diff_filespec *b,
 839                       const char *branch1,
 840                       const char *branch2)
 841 {
 842         mmfile_t orig, src1, src2;
 843         struct ll_merge_options ll_opts = {0};
 844         char *base_name, *name1, *name2;
 845         int merge_status;
 846
 847         ll_opts.renormalize = o->renormalize;
 848         ll_opts.xdl_opts = o->xdl_opts;
 849
 850         if (o->call_depth) {
 851                 ll_opts.virtual_ancestor = 1;
 852                 ll_opts.variant = 0;
 853         } else {
 854                 switch (o->recursive_variant) {
 855                 case MERGE_RECURSIVE_OURS:
 856                         ll_opts.variant = XDL_MERGE_FAVOR_OURS;
 857                         break;
 858                 case MERGE_RECURSIVE_THEIRS:
 859                         ll_opts.variant = XDL_MERGE_FAVOR_THEIRS;
 860                         break;
 861                 default:
 862                         ll_opts.variant = 0;
 863                         break;
 864                 }
 865         }
 866
 867         if (strcmp(a->path, b->path) ||
 868             (o->ancestor != NULL && strcmp(a->path, one->path) != 0)) {
 869                 base_name = o->ancestor == NULL ? NULL :
 870                         mkpathdup("%s:%s", o->ancestor, one->path);
 871                 name1 = mkpathdup("%s:%s", branch1, a->path);
 872                 name2 = mkpathdup("%s:%s", branch2, b->path);
 873         } else {
 874                 base_name = o->ancestor == NULL ? NULL :
 875                         mkpathdup("%s", o->ancestor);
 876                 name1 = mkpathdup("%s", branch1);
 877                 name2 = mkpathdup("%s", branch2);
 878         }
 879
 880         read_mmblob(&orig, one->sha1);
 881         read_mmblob(&src1, a->sha1);
 882         read_mmblob(&src2, b->sha1);
 883
 884         merge_status = ll_merge(result_buf, a->path, &orig, base_name,
 885                                 &src1, name1, &src2, name2, &ll_opts);
 886
 887         free(base_name);
 888         free(name1);
 889         free(name2);
 890         free(orig.ptr);
 891         free(src1.ptr);
 892         free(src2.ptr);
 893         return merge_status;
 894 }
 895
 896 static struct merge_file_info merge_file_1(struct merge_options *o,
 897                                            const struct diff_filespec *one,
 898                                            const struct diff_filespec *a,
 899                                            const struct diff_filespec *b,
 900                                            const char *branch1,
 901                                            const char *branch2)
 902 {
 903         struct merge_file_info result;
 904         result.merge = 0;
 905         result.clean = 1;
 906
 907         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 908                 result.clean = 0;
 909                 if (S_ISREG(a->mode)) {
 910                         result.mode = a->mode;
 911                         hashcpy(result.sha, a->sha1);
 912                 } else {
 913                         result.mode = b->mode;
 914                         hashcpy(result.sha, b->sha1);
 915                 }
 916         } else {
 917                 if (!sha_eq(a->sha1, one->sha1) && !sha_eq(b->sha1, one->sha1))
 918                         result.merge = 1;
 919
 920                 /*
 921                  * Merge modes
 922                  */
 923                 if (a->mode == b->mode || a->mode == one->mode)
 924                         result.mode = b->mode;
 925                 else {
 926                         result.mode = a->mode;
 927                         if (b->mode != one->mode) {
 928                                 result.clean = 0;
 929                                 result.merge = 1;
 930                         }
 931                 }
 932
 933                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, one->sha1))
 934                         hashcpy(result.sha, b->sha1);
 935                 else if (sha_eq(b->sha1, one->sha1))
 936                         hashcpy(result.sha, a->sha1);
 937                 else if (S_ISREG(a->mode)) {
 938                         mmbuffer_t result_buf;
 939                         int merge_status;
 940
 941                         merge_status = merge_3way(o, &result_buf, one, a, b,
 942                                                   branch1, branch2);
 943
 944                         if ((merge_status < 0) || !result_buf.ptr)
 945                                 die(_("Failed to execute internal merge"));
 946
 947                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 948                                             blob_type, result.sha))
 949                                 die(_("Unable to add %s to database"),
 950                                     a->path);
 951
 952                         free(result_buf.ptr);
 953                         result.clean = (merge_status == 0);
 954                 } else if (S_ISGITLINK(a->mode)) {
 955                         result.clean = merge_submodule(result.sha,
 956                                                        one->path, one->sha1,
 957                                                        a->sha1, b->sha1,
 958                                                        !o->call_depth);
 959                 } else if (S_ISLNK(a->mode)) {
 960                         hashcpy(result.sha, a->sha1);
 961
 962                         if (!sha_eq(a->sha1, b->sha1))
 963                                 result.clean = 0;
 964                 } else {
 965                         die(_("unsupported object type in the tree"));
 966                 }
 967         }
 968
 969         return result;
 970 }
 971
 972 static struct merge_file_info
 973 merge_file_special_markers(struct merge_options *o,
 974                            const struct diff_filespec *one,
 975                            const struct diff_filespec *a,
 976                            const struct diff_filespec *b,
 977                            const char *branch1,
 978                            const char *filename1,
 979                            const char *branch2,
 980                            const char *filename2)
 981 {
 982         char *side1 = NULL;
 983         char *side2 = NULL;
 984         struct merge_file_info mfi;
 985
 986         if (filename1)
 987                 side1 = xstrfmt("%s:%s", branch1, filename1);
 988         if (filename2)
 989                 side2 = xstrfmt("%s:%s", branch2, filename2);
 990
 991         mfi = merge_file_1(o, one, a, b,
 992                            side1 ? side1 : branch1, side2 ? side2 : branch2);
 993         free(side1);
 994         free(side2);
 995         return mfi;
 996 }
 997
 998 static struct merge_file_info merge_file_one(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 *branch1,
1004                                          const char *branch2)
1005 {
1006         struct diff_filespec one, a, b;
1007
1008         one.path = a.path = b.path = (char *)path;
1009         hashcpy(one.sha1, o_sha);
1010         one.mode = o_mode;
1011         hashcpy(a.sha1, a_sha);
1012         a.mode = a_mode;
1013         hashcpy(b.sha1, b_sha);
1014         b.mode = b_mode;
1015         return merge_file_1(o, &one, &a, &b, branch1, branch2);
1016 }
1017
1018 static void handle_change_delete(struct merge_options *o,
1019                                  const char *path,
1020                                  const unsigned char *o_sha, int o_mode,
1021                                  const unsigned char *a_sha, int a_mode,
1022                                  const unsigned char *b_sha, int b_mode,
1023                                  const char *change, const char *change_past)
1024 {
1025         char *renamed = NULL;
1026         if (dir_in_way(path, !o->call_depth)) {
1027                 renamed = unique_path(o, path, a_sha ? o->branch1 : o->branch2);
1028         }
1029
1030         if (o->call_depth) {
1031                 /*
1032                  * We cannot arbitrarily accept either a_sha or b_sha as
1033                  * correct; since there is no true "middle point" between
1034                  * them, simply reuse the base version for virtual merge base.
1035                  */
1036                 remove_file_from_cache(path);
1037                 update_file(o, 0, o_sha, o_mode, renamed ? renamed : path);
1038         } else if (!a_sha) {
1039                 if (!renamed) {
1040                         output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1041                                "and %s in %s. Version %s of %s left in tree."),
1042                                change, path, o->branch1, change_past,
1043                                o->branch2, o->branch2, path);
1044                         update_file(o, 0, b_sha, b_mode, path);
1045                 } else {
1046                         output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1047                                "and %s in %s. Version %s of %s left in tree at %s."),
1048                                change, path, o->branch1, change_past,
1049                                o->branch2, o->branch2, path, renamed);
1050                         update_file(o, 0, b_sha, b_mode, renamed);
1051                 }
1052         } else {
1053                 if (!renamed) {
1054                         output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1055                                "and %s in %s. Version %s of %s left in tree."),
1056                                change, path, o->branch2, change_past,
1057                                o->branch1, o->branch1, path);
1058                 } else {
1059                         output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1060                                "and %s in %s. Version %s of %s left in tree at %s."),
1061                                change, path, o->branch2, change_past,
1062                                o->branch1, o->branch1, path, renamed);
1063                         update_file(o, 0, a_sha, a_mode, renamed);
1064                 }
1065                 /*
1066                  * No need to call update_file() on path when !renamed, since
1067                  * that would needlessly touch path.  We could call
1068                  * update_file_flags() with update_cache=0 and update_wd=0,
1069                  * but that's a no-op.
1070                  */
1071         }
1072         free(renamed);
1073 }
1074
1075 static void conflict_rename_delete(struct merge_options *o,
1076                                    struct diff_filepair *pair,
1077                                    const char *rename_branch,
1078                                    const char *other_branch)
1079 {
1080         const struct diff_filespec *orig = pair->one;
1081         const struct diff_filespec *dest = pair->two;
1082         const unsigned char *a_sha = NULL;
1083         const unsigned char *b_sha = NULL;
1084         int a_mode = 0;
1085         int b_mode = 0;
1086
1087         if (rename_branch == o->branch1) {
1088                 a_sha = dest->sha1;
1089                 a_mode = dest->mode;
1090         } else {
1091                 b_sha = dest->sha1;
1092                 b_mode = dest->mode;
1093         }
1094
1095         handle_change_delete(o,
1096                              o->call_depth ? orig->path : dest->path,
1097                              orig->sha1, orig->mode,
1098                              a_sha, a_mode,
1099                              b_sha, b_mode,
1100                              _("rename"), _("renamed"));
1101
1102         if (o->call_depth) {
1103                 remove_file_from_cache(dest->path);
1104         } else {
1105                 update_stages(dest->path, NULL,
1106                               rename_branch == o->branch1 ? dest : NULL,
1107                               rename_branch == o->branch1 ? NULL : dest);
1108         }
1109
1110 }
1111
1112 static struct diff_filespec *filespec_from_entry(struct diff_filespec *target,
1113                                                  struct stage_data *entry,
1114                                                  int stage)
1115 {
1116         unsigned char *sha = entry->stages[stage].sha;
1117         unsigned mode = entry->stages[stage].mode;
1118         if (mode == 0 || is_null_sha1(sha))
1119                 return NULL;
1120         hashcpy(target->sha1, sha);
1121         target->mode = mode;
1122         return target;
1123 }
1124
1125 static void handle_file(struct merge_options *o,
1126                         struct diff_filespec *rename,
1127                         int stage,
1128                         struct rename_conflict_info *ci)
1129 {
1130         char *dst_name = rename->path;
1131         struct stage_data *dst_entry;
1132         const char *cur_branch, *other_branch;
1133         struct diff_filespec other;
1134         struct diff_filespec *add;
1135
1136         if (stage == 2) {
1137                 dst_entry = ci->dst_entry1;
1138                 cur_branch = ci->branch1;
1139                 other_branch = ci->branch2;
1140         } else {
1141                 dst_entry = ci->dst_entry2;
1142                 cur_branch = ci->branch2;
1143                 other_branch = ci->branch1;
1144         }
1145
1146         add = filespec_from_entry(&other, dst_entry, stage ^ 1);
1147         if (add) {
1148                 char *add_name = unique_path(o, rename->path, other_branch);
1149                 update_file(o, 0, add->sha1, add->mode, add_name);
1150
1151                 remove_file(o, 0, rename->path, 0);
1152                 dst_name = unique_path(o, rename->path, cur_branch);
1153         } else {
1154                 if (dir_in_way(rename->path, !o->call_depth)) {
1155                         dst_name = unique_path(o, rename->path, cur_branch);
1156                         output(o, 1, _("%s is a directory in %s adding as %s instead"),
1157                                rename->path, other_branch, dst_name);
1158                 }
1159         }
1160         update_file(o, 0, rename->sha1, rename->mode, dst_name);
1161         if (stage == 2)
1162                 update_stages(rename->path, NULL, rename, add);
1163         else
1164                 update_stages(rename->path, NULL, add, rename);
1165
1166         if (dst_name != rename->path)
1167                 free(dst_name);
1168 }
1169
1170 static void conflict_rename_rename_1to2(struct merge_options *o,
1171                                         struct rename_conflict_info *ci)
1172 {
1173         /* One file was renamed in both branches, but to different names. */
1174         struct diff_filespec *one = ci->pair1->one;
1175         struct diff_filespec *a = ci->pair1->two;
1176         struct diff_filespec *b = ci->pair2->two;
1177
1178         output(o, 1, _("CONFLICT (rename/rename): "
1179                "Rename \"%s\"->\"%s\" in branch \"%s\" "
1180                "rename \"%s\"->\"%s\" in \"%s\"%s"),
1181                one->path, a->path, ci->branch1,
1182                one->path, b->path, ci->branch2,
1183                o->call_depth ? _(" (left unresolved)") : "");
1184         if (o->call_depth) {
1185                 struct merge_file_info mfi;
1186                 struct diff_filespec other;
1187                 struct diff_filespec *add;
1188                 mfi = merge_file_one(o, one->path,
1189                                  one->sha1, one->mode,
1190                                  a->sha1, a->mode,
1191                                  b->sha1, b->mode,
1192                                  ci->branch1, ci->branch2);
1193                 /*
1194                  * FIXME: For rename/add-source conflicts (if we could detect
1195                  * such), this is wrong.  We should instead find a unique
1196                  * pathname and then either rename the add-source file to that
1197                  * unique path, or use that unique path instead of src here.
1198                  */
1199                 update_file(o, 0, mfi.sha, mfi.mode, one->path);
1200
1201                 /*
1202                  * Above, we put the merged content at the merge-base's
1203                  * path.  Now we usually need to delete both a->path and
1204                  * b->path.  However, the rename on each side of the merge
1205                  * could also be involved in a rename/add conflict.  In
1206                  * such cases, we should keep the added file around,
1207                  * resolving the conflict at that path in its favor.
1208                  */
1209                 add = filespec_from_entry(&other, ci->dst_entry1, 2 ^ 1);
1210                 if (add)
1211                         update_file(o, 0, add->sha1, add->mode, a->path);
1212                 else
1213                         remove_file_from_cache(a->path);
1214                 add = filespec_from_entry(&other, ci->dst_entry2, 3 ^ 1);
1215                 if (add)
1216                         update_file(o, 0, add->sha1, add->mode, b->path);
1217                 else
1218                         remove_file_from_cache(b->path);
1219         } else {
1220                 handle_file(o, a, 2, ci);
1221                 handle_file(o, b, 3, ci);
1222         }
1223 }
1224
1225 static void conflict_rename_rename_2to1(struct merge_options *o,
1226                                         struct rename_conflict_info *ci)
1227 {
1228         /* Two files, a & b, were renamed to the same thing, c. */
1229         struct diff_filespec *a = ci->pair1->one;
1230         struct diff_filespec *b = ci->pair2->one;
1231         struct diff_filespec *c1 = ci->pair1->two;
1232         struct diff_filespec *c2 = ci->pair2->two;
1233         char *path = c1->path; /* == c2->path */
1234         struct merge_file_info mfi_c1;
1235         struct merge_file_info mfi_c2;
1236
1237         output(o, 1, _("CONFLICT (rename/rename): "
1238                "Rename %s->%s in %s. "
1239                "Rename %s->%s in %s"),
1240                a->path, c1->path, ci->branch1,
1241                b->path, c2->path, ci->branch2);
1242
1243         remove_file(o, 1, a->path, o->call_depth || would_lose_untracked(a->path));
1244         remove_file(o, 1, b->path, o->call_depth || would_lose_untracked(b->path));
1245
1246         mfi_c1 = merge_file_special_markers(o, a, c1, &ci->ren1_other,
1247                                             o->branch1, c1->path,
1248                                             o->branch2, ci->ren1_other.path);
1249         mfi_c2 = merge_file_special_markers(o, b, &ci->ren2_other, c2,
1250                                             o->branch1, ci->ren2_other.path,
1251                                             o->branch2, c2->path);
1252
1253         if (o->call_depth) {
1254                 /*
1255                  * If mfi_c1.clean && mfi_c2.clean, then it might make
1256                  * sense to do a two-way merge of those results.  But, I
1257                  * think in all cases, it makes sense to have the virtual
1258                  * merge base just undo the renames; they can be detected
1259                  * again later for the non-recursive merge.
1260                  */
1261                 remove_file(o, 0, path, 0);
1262                 update_file(o, 0, mfi_c1.sha, mfi_c1.mode, a->path);
1263                 update_file(o, 0, mfi_c2.sha, mfi_c2.mode, b->path);
1264         } else {
1265                 char *new_path1 = unique_path(o, path, ci->branch1);
1266                 char *new_path2 = unique_path(o, path, ci->branch2);
1267                 output(o, 1, _("Renaming %s to %s and %s to %s instead"),
1268                        a->path, new_path1, b->path, new_path2);
1269                 remove_file(o, 0, path, 0);
1270                 update_file(o, 0, mfi_c1.sha, mfi_c1.mode, new_path1);
1271                 update_file(o, 0, mfi_c2.sha, mfi_c2.mode, new_path2);
1272                 free(new_path2);
1273                 free(new_path1);
1274         }
1275 }
1276
1277 static int process_renames(struct merge_options *o,
1278                            struct string_list *a_renames,
1279                            struct string_list *b_renames)
1280 {
1281         int clean_merge = 1, i, j;
1282         struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
1283         struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
1284         const struct rename *sre;
1285
1286         for (i = 0; i < a_renames->nr; i++) {
1287                 sre = a_renames->items[i].util;
1288                 string_list_insert(&a_by_dst, sre->pair->two->path)->util
1289                         = (void *)sre;
1290         }
1291         for (i = 0; i < b_renames->nr; i++) {
1292                 sre = b_renames->items[i].util;
1293                 string_list_insert(&b_by_dst, sre->pair->two->path)->util
1294                         = (void *)sre;
1295         }
1296
1297         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
1298                 struct string_list *renames1, *renames2Dst;
1299                 struct rename *ren1 = NULL, *ren2 = NULL;
1300                 const char *branch1, *branch2;
1301                 const char *ren1_src, *ren1_dst;
1302                 struct string_list_item *lookup;
1303
1304                 if (i >= a_renames->nr) {
1305                         ren2 = b_renames->items[j++].util;
1306                 } else if (j >= b_renames->nr) {
1307                         ren1 = a_renames->items[i++].util;
1308                 } else {
1309                         int compare = strcmp(a_renames->items[i].string,
1310                                              b_renames->items[j].string);
1311                         if (compare <= 0)
1312                                 ren1 = a_renames->items[i++].util;
1313                         if (compare >= 0)
1314                                 ren2 = b_renames->items[j++].util;
1315                 }
1316
1317                 /* TODO: refactor, so that 1/2 are not needed */
1318                 if (ren1) {
1319                         renames1 = a_renames;
1320                         renames2Dst = &b_by_dst;
1321                         branch1 = o->branch1;
1322                         branch2 = o->branch2;
1323                 } else {
1324                         struct rename *tmp;
1325                         renames1 = b_renames;
1326                         renames2Dst = &a_by_dst;
1327                         branch1 = o->branch2;
1328                         branch2 = o->branch1;
1329                         tmp = ren2;
1330                         ren2 = ren1;
1331                         ren1 = tmp;
1332                 }
1333
1334                 if (ren1->processed)
1335                         continue;
1336                 ren1->processed = 1;
1337                 ren1->dst_entry->processed = 1;
1338                 /* BUG: We should only mark src_entry as processed if we
1339                  * are not dealing with a rename + add-source case.
1340                  */
1341                 ren1->src_entry->processed = 1;
1342
1343                 ren1_src = ren1->pair->one->path;
1344                 ren1_dst = ren1->pair->two->path;
1345
1346                 if (ren2) {
1347                         /* One file renamed on both sides */
1348                         const char *ren2_src = ren2->pair->one->path;
1349                         const char *ren2_dst = ren2->pair->two->path;
1350                         enum rename_type rename_type;
1351                         if (strcmp(ren1_src, ren2_src) != 0)
1352                                 die("ren1_src != ren2_src");
1353                         ren2->dst_entry->processed = 1;
1354                         ren2->processed = 1;
1355                         if (strcmp(ren1_dst, ren2_dst) != 0) {
1356                                 rename_type = RENAME_ONE_FILE_TO_TWO;
1357                                 clean_merge = 0;
1358                         } else {
1359                                 rename_type = RENAME_ONE_FILE_TO_ONE;
1360                                 /* BUG: We should only remove ren1_src in
1361                                  * the base stage (think of rename +
1362                                  * add-source cases).
1363                                  */
1364                                 remove_file(o, 1, ren1_src, 1);
1365                                 update_entry(ren1->dst_entry,
1366                                              ren1->pair->one,
1367                                              ren1->pair->two,
1368                                              ren2->pair->two);
1369                         }
1370                         setup_rename_conflict_info(rename_type,
1371                                                    ren1->pair,
1372                                                    ren2->pair,
1373                                                    branch1,
1374                                                    branch2,
1375                                                    ren1->dst_entry,
1376                                                    ren2->dst_entry,
1377                                                    o,
1378                                                    NULL,
1379                                                    NULL);
1380                 } else if ((lookup = string_list_lookup(renames2Dst, ren1_dst))) {
1381                         /* Two different files renamed to the same thing */
1382                         char *ren2_dst;
1383                         ren2 = lookup->util;
1384                         ren2_dst = ren2->pair->two->path;
1385                         if (strcmp(ren1_dst, ren2_dst) != 0)
1386                                 die("ren1_dst != ren2_dst");
1387
1388                         clean_merge = 0;
1389                         ren2->processed = 1;
1390                         /*
1391                          * BUG: We should only mark src_entry as processed
1392                          * if we are not dealing with a rename + add-source
1393                          * case.
1394                          */
1395                         ren2->src_entry->processed = 1;
1396
1397                         setup_rename_conflict_info(RENAME_TWO_FILES_TO_ONE,
1398                                                    ren1->pair,
1399                                                    ren2->pair,
1400                                                    branch1,
1401                                                    branch2,
1402                                                    ren1->dst_entry,
1403                                                    ren2->dst_entry,
1404                                                    o,
1405                                                    ren1->src_entry,
1406                                                    ren2->src_entry);
1407
1408                 } else {
1409                         /* Renamed in 1, maybe changed in 2 */
1410                         /* we only use sha1 and mode of these */
1411                         struct diff_filespec src_other, dst_other;
1412                         int try_merge;
1413
1414                         /*
1415                          * unpack_trees loads entries from common-commit
1416                          * into stage 1, from head-commit into stage 2, and
1417                          * from merge-commit into stage 3.  We keep track
1418                          * of which side corresponds to the rename.
1419                          */
1420                         int renamed_stage = a_renames == renames1 ? 2 : 3;
1421                         int other_stage =   a_renames == renames1 ? 3 : 2;
1422
1423                         /* BUG: We should only remove ren1_src in the base
1424                          * stage and in other_stage (think of rename +
1425                          * add-source case).
1426                          */
1427                         remove_file(o, 1, ren1_src,
1428                                     renamed_stage == 2 || !was_tracked(ren1_src));
1429
1430                         hashcpy(src_other.sha1, ren1->src_entry->stages[other_stage].sha);
1431                         src_other.mode = ren1->src_entry->stages[other_stage].mode;
1432                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[other_stage].sha);
1433                         dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
1434                         try_merge = 0;
1435
1436                         if (sha_eq(src_other.sha1, null_sha1)) {
1437                                 setup_rename_conflict_info(RENAME_DELETE,
1438                                                            ren1->pair,
1439                                                            NULL,
1440                                                            branch1,
1441                                                            branch2,
1442                                                            ren1->dst_entry,
1443                                                            NULL,
1444                                                            o,
1445                                                            NULL,
1446                                                            NULL);
1447                         } else if ((dst_other.mode == ren1->pair->two->mode) &&
1448                                    sha_eq(dst_other.sha1, ren1->pair->two->sha1)) {
1449                                 /*
1450                                  * Added file on the other side identical to
1451                                  * the file being renamed: clean merge.
1452                                  * Also, there is no need to overwrite the
1453                                  * file already in the working copy, so call
1454                                  * update_file_flags() instead of
1455                                  * update_file().
1456                                  */
1457                                 update_file_flags(o,
1458                                                   ren1->pair->two->sha1,
1459                                                   ren1->pair->two->mode,
1460                                                   ren1_dst,
1461                                                   1, /* update_cache */
1462                                                   0  /* update_wd    */);
1463                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
1464                                 clean_merge = 0;
1465                                 try_merge = 1;
1466                                 output(o, 1, _("CONFLICT (rename/add): Rename %s->%s in %s. "
1467                                        "%s added in %s"),
1468                                        ren1_src, ren1_dst, branch1,
1469                                        ren1_dst, branch2);
1470                                 if (o->call_depth) {
1471                                         struct merge_file_info mfi;
1472                                         mfi = merge_file_one(o, ren1_dst, null_sha1, 0,
1473                                                          ren1->pair->two->sha1, ren1->pair->two->mode,
1474                                                          dst_other.sha1, dst_other.mode,
1475                                                          branch1, branch2);
1476                                         output(o, 1, _("Adding merged %s"), ren1_dst);
1477                                         update_file(o, 0, mfi.sha, mfi.mode, ren1_dst);
1478                                         try_merge = 0;
1479                                 } else {
1480                                         char *new_path = unique_path(o, ren1_dst, branch2);
1481                                         output(o, 1, _("Adding as %s instead"), new_path);
1482                                         update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
1483                                         free(new_path);
1484                                 }
1485                         } else
1486                                 try_merge = 1;
1487
1488                         if (try_merge) {
1489                                 struct diff_filespec *one, *a, *b;
1490                                 src_other.path = (char *)ren1_src;
1491
1492                                 one = ren1->pair->one;
1493                                 if (a_renames == renames1) {
1494                                         a = ren1->pair->two;
1495                                         b = &src_other;
1496                                 } else {
1497                                         b = ren1->pair->two;
1498                                         a = &src_other;
1499                                 }
1500                                 update_entry(ren1->dst_entry, one, a, b);
1501                                 setup_rename_conflict_info(RENAME_NORMAL,
1502                                                            ren1->pair,
1503                                                            NULL,
1504                                                            branch1,
1505                                                            NULL,
1506                                                            ren1->dst_entry,
1507                                                            NULL,
1508                                                            o,
1509                                                            NULL,
1510                                                            NULL);
1511                         }
1512                 }
1513         }
1514         string_list_clear(&a_by_dst, 0);
1515         string_list_clear(&b_by_dst, 0);
1516
1517         return clean_merge;
1518 }
1519
1520 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1521 {
1522         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1523 }
1524
1525 static int read_sha1_strbuf(const unsigned char *sha1, struct strbuf *dst)
1526 {
1527         void *buf;
1528         enum object_type type;
1529         unsigned long size;
1530         buf = read_sha1_file(sha1, &type, &size);
1531         if (!buf)
1532                 return error(_("cannot read object %s"), sha1_to_hex(sha1));
1533         if (type != OBJ_BLOB) {
1534                 free(buf);
1535                 return error(_("object %s is not a blob"), sha1_to_hex(sha1));
1536         }
1537         strbuf_attach(dst, buf, size, size + 1);
1538         return 0;
1539 }
1540
1541 static int blob_unchanged(const unsigned char *o_sha,
1542                           unsigned o_mode,
1543                           const unsigned char *a_sha,
1544                           unsigned a_mode,
1545                           int renormalize, const char *path)
1546 {
1547         struct strbuf o = STRBUF_INIT;
1548         struct strbuf a = STRBUF_INIT;
1549         int ret = 0; /* assume changed for safety */
1550
1551         if (a_mode != o_mode)
1552                 return 0;
1553         if (sha_eq(o_sha, a_sha))
1554                 return 1;
1555         if (!renormalize)
1556                 return 0;
1557
1558         assert(o_sha && a_sha);
1559         if (read_sha1_strbuf(o_sha, &o) || read_sha1_strbuf(a_sha, &a))
1560                 goto error_return;
1561         /*
1562          * Note: binary | is used so that both renormalizations are
1563          * performed.  Comparison can be skipped if both files are
1564          * unchanged since their sha1s have already been compared.
1565          */
1566         if (renormalize_buffer(path, o.buf, o.len, &o) |
1567             renormalize_buffer(path, a.buf, a.len, &a))
1568                 ret = (o.len == a.len && !memcmp(o.buf, a.buf, o.len));
1569
1570 error_return:
1571         strbuf_release(&o);
1572         strbuf_release(&a);
1573         return ret;
1574 }
1575
1576 static void handle_modify_delete(struct merge_options *o,
1577                                  const char *path,
1578                                  unsigned char *o_sha, int o_mode,
1579                                  unsigned char *a_sha, int a_mode,
1580                                  unsigned char *b_sha, int b_mode)
1581 {
1582         handle_change_delete(o,
1583                              path,
1584                              o_sha, o_mode,
1585                              a_sha, a_mode,
1586                              b_sha, b_mode,
1587                              _("modify"), _("modified"));
1588 }
1589
1590 static int merge_content(struct merge_options *o,
1591                          const char *path,
1592                          unsigned char *o_sha, int o_mode,
1593                          unsigned char *a_sha, int a_mode,
1594                          unsigned char *b_sha, int b_mode,
1595                          struct rename_conflict_info *rename_conflict_info)
1596 {
1597         const char *reason = _("content");
1598         const char *path1 = NULL, *path2 = NULL;
1599         struct merge_file_info mfi;
1600         struct diff_filespec one, a, b;
1601         unsigned df_conflict_remains = 0;
1602
1603         if (!o_sha) {
1604                 reason = _("add/add");
1605                 o_sha = (unsigned char *)null_sha1;
1606         }
1607         one.path = a.path = b.path = (char *)path;
1608         hashcpy(one.sha1, o_sha);
1609         one.mode = o_mode;
1610         hashcpy(a.sha1, a_sha);
1611         a.mode = a_mode;
1612         hashcpy(b.sha1, b_sha);
1613         b.mode = b_mode;
1614
1615         if (rename_conflict_info) {
1616                 struct diff_filepair *pair1 = rename_conflict_info->pair1;
1617
1618                 path1 = (o->branch1 == rename_conflict_info->branch1) ?
1619                         pair1->two->path : pair1->one->path;
1620                 /* If rename_conflict_info->pair2 != NULL, we are in
1621                  * RENAME_ONE_FILE_TO_ONE case.  Otherwise, we have a
1622                  * normal rename.
1623                  */
1624                 path2 = (rename_conflict_info->pair2 ||
1625                          o->branch2 == rename_conflict_info->branch1) ?
1626                         pair1->two->path : pair1->one->path;
1627
1628                 if (dir_in_way(path, !o->call_depth))
1629                         df_conflict_remains = 1;
1630         }
1631         mfi = merge_file_special_markers(o, &one, &a, &b,
1632                                          o->branch1, path1,
1633                                          o->branch2, path2);
1634
1635         if (mfi.clean && !df_conflict_remains &&
1636             sha_eq(mfi.sha, a_sha) && mfi.mode == a_mode) {
1637                 int path_renamed_outside_HEAD;
1638                 output(o, 3, _("Skipped %s (merged same as existing)"), path);
1639                 /*
1640                  * The content merge resulted in the same file contents we
1641                  * already had.  We can return early if those file contents
1642                  * are recorded at the correct path (which may not be true
1643                  * if the merge involves a rename).
1644                  */
1645                 path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
1646                 if (!path_renamed_outside_HEAD) {
1647                         add_cacheinfo(mfi.mode, mfi.sha, path,
1648                                       0, (!o->call_depth), 0);
1649                         return mfi.clean;
1650                 }
1651         } else
1652                 output(o, 2, _("Auto-merging %s"), path);
1653
1654         if (!mfi.clean) {
1655                 if (S_ISGITLINK(mfi.mode))
1656                         reason = _("submodule");
1657                 output(o, 1, _("CONFLICT (%s): Merge conflict in %s"),
1658                                 reason, path);
1659                 if (rename_conflict_info && !df_conflict_remains)
1660                         update_stages(path, &one, &a, &b);
1661         }
1662
1663         if (df_conflict_remains) {
1664                 char *new_path;
1665                 if (o->call_depth) {
1666                         remove_file_from_cache(path);
1667                 } else {
1668                         if (!mfi.clean)
1669                                 update_stages(path, &one, &a, &b);
1670                         else {
1671                                 int file_from_stage2 = was_tracked(path);
1672                                 struct diff_filespec merged;
1673                                 hashcpy(merged.sha1, mfi.sha);
1674                                 merged.mode = mfi.mode;
1675
1676                                 update_stages(path, NULL,
1677                                               file_from_stage2 ? &merged : NULL,
1678                                               file_from_stage2 ? NULL : &merged);
1679                         }
1680
1681                 }
1682                 new_path = unique_path(o, path, rename_conflict_info->branch1);
1683                 output(o, 1, _("Adding as %s instead"), new_path);
1684                 update_file(o, 0, mfi.sha, mfi.mode, new_path);
1685                 free(new_path);
1686                 mfi.clean = 0;
1687         } else {
1688                 update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
1689         }
1690         return mfi.clean;
1691
1692 }
1693
1694 /* Per entry merge function */
1695 static int process_entry(struct merge_options *o,
1696                          const char *path, struct stage_data *entry)
1697 {
1698         int clean_merge = 1;
1699         int normalize = o->renormalize;
1700         unsigned o_mode = entry->stages[1].mode;
1701         unsigned a_mode = entry->stages[2].mode;
1702         unsigned b_mode = entry->stages[3].mode;
1703         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1704         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1705         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1706
1707         entry->processed = 1;
1708         if (entry->rename_conflict_info) {
1709                 struct rename_conflict_info *conflict_info = entry->rename_conflict_info;
1710                 switch (conflict_info->rename_type) {
1711                 case RENAME_NORMAL:
1712                 case RENAME_ONE_FILE_TO_ONE:
1713                         clean_merge = merge_content(o, path,
1714                                                     o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
1715                                                     conflict_info);
1716                         break;
1717                 case RENAME_DELETE:
1718                         clean_merge = 0;
1719                         conflict_rename_delete(o, conflict_info->pair1,
1720                                                conflict_info->branch1,
1721                                                conflict_info->branch2);
1722                         break;
1723                 case RENAME_ONE_FILE_TO_TWO:
1724                         clean_merge = 0;
1725                         conflict_rename_rename_1to2(o, conflict_info);
1726                         break;
1727                 case RENAME_TWO_FILES_TO_ONE:
1728                         clean_merge = 0;
1729                         conflict_rename_rename_2to1(o, conflict_info);
1730                         break;
1731                 default:
1732                         entry->processed = 0;
1733                         break;
1734                 }
1735         } else if (o_sha && (!a_sha || !b_sha)) {
1736                 /* Case A: Deleted in one */
1737                 if ((!a_sha && !b_sha) ||
1738                     (!b_sha && blob_unchanged(o_sha, o_mode, a_sha, a_mode, normalize, path)) ||
1739                     (!a_sha && blob_unchanged(o_sha, o_mode, b_sha, b_mode, normalize, path))) {
1740                         /* Deleted in both or deleted in one and
1741                          * unchanged in the other */
1742                         if (a_sha)
1743                                 output(o, 2, _("Removing %s"), path);
1744                         /* do not touch working file if it did not exist */
1745                         remove_file(o, 1, path, !a_sha);
1746                 } else {
1747                         /* Modify/delete; deleted side may have put a directory in the way */
1748                         clean_merge = 0;
1749                         handle_modify_delete(o, path, o_sha, o_mode,
1750                                              a_sha, a_mode, b_sha, b_mode);
1751                 }
1752         } else if ((!o_sha && a_sha && !b_sha) ||
1753                    (!o_sha && !a_sha && b_sha)) {
1754                 /* Case B: Added in one. */
1755                 /* [nothing|directory] -> ([nothing|directory], file) */
1756
1757                 const char *add_branch;
1758                 const char *other_branch;
1759                 unsigned mode;
1760                 const unsigned char *sha;
1761                 const char *conf;
1762
1763                 if (a_sha) {
1764                         add_branch = o->branch1;
1765                         other_branch = o->branch2;
1766                         mode = a_mode;
1767                         sha = a_sha;
1768                         conf = _("file/directory");
1769                 } else {
1770                         add_branch = o->branch2;
1771                         other_branch = o->branch1;
1772                         mode = b_mode;
1773                         sha = b_sha;
1774                         conf = _("directory/file");
1775                 }
1776                 if (dir_in_way(path, !o->call_depth)) {
1777                         char *new_path = unique_path(o, path, add_branch);
1778                         clean_merge = 0;
1779                         output(o, 1, _("CONFLICT (%s): There is a directory with name %s in %s. "
1780                                "Adding %s as %s"),
1781                                conf, path, other_branch, path, new_path);
1782                         update_file(o, 0, sha, mode, new_path);
1783                         if (o->call_depth)
1784                                 remove_file_from_cache(path);
1785                         free(new_path);
1786                 } else {
1787                         output(o, 2, _("Adding %s"), path);
1788                         /* do not overwrite file if already present */
1789                         update_file_flags(o, sha, mode, path, 1, !a_sha);
1790                 }
1791         } else if (a_sha && b_sha) {
1792                 /* Case C: Added in both (check for same permissions) and */
1793                 /* case D: Modified in both, but differently. */
1794                 clean_merge = merge_content(o, path,
1795                                             o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
1796                                             NULL);
1797         } else if (!o_sha && !a_sha && !b_sha) {
1798                 /*
1799                  * this entry was deleted altogether. a_mode == 0 means
1800                  * we had that path and want to actively remove it.
1801                  */
1802                 remove_file(o, 1, path, !a_mode);
1803         } else
1804                 die(_("Fatal merge failure, shouldn't happen."));
1805
1806         return clean_merge;
1807 }
1808
1809 int merge_trees(struct merge_options *o,
1810                 struct tree *head,
1811                 struct tree *merge,
1812                 struct tree *common,
1813                 struct tree **result)
1814 {
1815         int code, clean;
1816
1817         if (o->subtree_shift) {
1818                 merge = shift_tree_object(head, merge, o->subtree_shift);
1819                 common = shift_tree_object(head, common, o->subtree_shift);
1820         }
1821
1822         if (sha_eq(common->object.oid.hash, merge->object.oid.hash)) {
1823                 output(o, 0, _("Already up-to-date!"));
1824                 *result = head;
1825                 return 1;
1826         }
1827
1828         code = git_merge_trees(o->call_depth, common, head, merge);
1829
1830         if (code != 0) {
1831                 if (show(o, 4) || o->call_depth)
1832                         die(_("merging of trees %s and %s failed"),
1833                             oid_to_hex(&head->object.oid),
1834                             oid_to_hex(&merge->object.oid));
1835                 else
1836                         exit(128);
1837         }
1838
1839         if (unmerged_cache()) {
1840                 struct string_list *entries, *re_head, *re_merge;
1841                 int i;
1842                 string_list_clear(&o->current_file_set, 1);
1843                 string_list_clear(&o->current_directory_set, 1);
1844                 get_files_dirs(o, head);
1845                 get_files_dirs(o, merge);
1846
1847                 entries = get_unmerged();
1848                 record_df_conflict_files(o, entries);
1849                 re_head  = get_renames(o, head, common, head, merge, entries);
1850                 re_merge = get_renames(o, merge, common, head, merge, entries);
1851                 clean = process_renames(o, re_head, re_merge);
1852                 for (i = entries->nr-1; 0 <= i; i--) {
1853                         const char *path = entries->items[i].string;
1854                         struct stage_data *e = entries->items[i].util;
1855                         if (!e->processed
1856                                 && !process_entry(o, path, e))
1857                                 clean = 0;
1858                 }
1859                 for (i = 0; i < entries->nr; i++) {
1860                         struct stage_data *e = entries->items[i].util;
1861                         if (!e->processed)
1862                                 die(_("Unprocessed path??? %s"),
1863                                     entries->items[i].string);
1864                 }
1865
1866                 string_list_clear(re_merge, 0);
1867                 string_list_clear(re_head, 0);
1868                 string_list_clear(entries, 1);
1869
1870                 free(re_merge);
1871                 free(re_head);
1872                 free(entries);
1873         }
1874         else
1875                 clean = 1;
1876
1877         if (o->call_depth)
1878                 *result = write_tree_from_memory(o);
1879
1880         return clean;
1881 }
1882
1883 static struct commit_list *reverse_commit_list(struct commit_list *list)
1884 {
1885         struct commit_list *next = NULL, *current, *backup;
1886         for (current = list; current; current = backup) {
1887                 backup = current->next;
1888                 current->next = next;
1889                 next = current;
1890         }
1891         return next;
1892 }
1893
1894 /*
1895  * Merge the commits h1 and h2, return the resulting virtual
1896  * commit object and a flag indicating the cleanness of the merge.
1897  */
1898 int merge_recursive(struct merge_options *o,
1899                     struct commit *h1,
1900                     struct commit *h2,
1901                     struct commit_list *ca,
1902                     struct commit **result)
1903 {
1904         struct commit_list *iter;
1905         struct commit *merged_common_ancestors;
1906         struct tree *mrtree = mrtree;
1907         int clean;
1908
1909         if (show(o, 4)) {
1910                 output(o, 4, _("Merging:"));
1911                 output_commit_title(o, h1);
1912                 output_commit_title(o, h2);
1913         }
1914
1915         if (!ca) {
1916                 ca = get_merge_bases(h1, h2);
1917                 ca = reverse_commit_list(ca);
1918         }
1919
1920         if (show(o, 5)) {
1921                 unsigned cnt = commit_list_count(ca);
1922
1923                 output(o, 5, Q_("found %u common ancestor:",
1924                                 "found %u common ancestors:", cnt), cnt);
1925                 for (iter = ca; iter; iter = iter->next)
1926                         output_commit_title(o, iter->item);
1927         }
1928
1929         merged_common_ancestors = pop_commit(&ca);
1930         if (merged_common_ancestors == NULL) {
1931                 /* if there is no common ancestor, use an empty tree */
1932                 struct tree *tree;
1933
1934                 tree = lookup_tree(EMPTY_TREE_SHA1_BIN);
1935                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1936         }
1937
1938         for (iter = ca; iter; iter = iter->next) {
1939                 const char *saved_b1, *saved_b2;
1940                 o->call_depth++;
1941                 /*
1942                  * When the merge fails, the result contains files
1943                  * with conflict markers. The cleanness flag is
1944                  * ignored, it was never actually used, as result of
1945                  * merge_trees has always overwritten it: the committed
1946                  * "conflicts" were already resolved.
1947                  */
1948                 discard_cache();
1949                 saved_b1 = o->branch1;
1950                 saved_b2 = o->branch2;
1951                 o->branch1 = "Temporary merge branch 1";
1952                 o->branch2 = "Temporary merge branch 2";
1953                 merge_recursive(o, merged_common_ancestors, iter->item,
1954                                 NULL, &merged_common_ancestors);
1955                 o->branch1 = saved_b1;
1956                 o->branch2 = saved_b2;
1957                 o->call_depth--;
1958
1959                 if (!merged_common_ancestors)
1960                         die(_("merge returned no commit"));
1961         }
1962
1963         discard_cache();
1964         if (!o->call_depth)
1965                 read_cache();
1966
1967         o->ancestor = "merged common ancestors";
1968         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
1969                             &mrtree);
1970
1971         if (o->call_depth) {
1972                 *result = make_virtual_commit(mrtree, "merged tree");
1973                 commit_list_insert(h1, &(*result)->parents);
1974                 commit_list_insert(h2, &(*result)->parents->next);
1975         }
1976         flush_output(o);
1977         if (show(o, 2))
1978                 diff_warn_rename_limit("merge.renamelimit",
1979                                        o->needed_rename_limit, 0);
1980         return clean;
1981 }
1982
1983 static struct commit *get_ref(const unsigned char *sha1, const char *name)
1984 {
1985         struct object *object;
1986
1987         object = deref_tag(parse_object(sha1), name, strlen(name));
1988         if (!object)
1989                 return NULL;
1990         if (object->type == OBJ_TREE)
1991                 return make_virtual_commit((struct tree*)object, name);
1992         if (object->type != OBJ_COMMIT)
1993                 return NULL;
1994         if (parse_commit((struct commit *)object))
1995                 return NULL;
1996         return (struct commit *)object;
1997 }
1998
1999 int merge_recursive_generic(struct merge_options *o,
2000                             const unsigned char *head,
2001                             const unsigned char *merge,
2002                             int num_base_list,
2003                             const unsigned char **base_list,
2004                             struct commit **result)
2005 {
2006         int clean;
2007         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
2008         struct commit *head_commit = get_ref(head, o->branch1);
2009         struct commit *next_commit = get_ref(merge, o->branch2);
2010         struct commit_list *ca = NULL;
2011
2012         if (base_list) {
2013                 int i;
2014                 for (i = 0; i < num_base_list; ++i) {
2015                         struct commit *base;
2016                         if (!(base = get_ref(base_list[i], sha1_to_hex(base_list[i]))))
2017                                 return error(_("Could not parse object '%s'"),
2018                                         sha1_to_hex(base_list[i]));
2019                         commit_list_insert(base, &ca);
2020                 }
2021         }
2022
2023         hold_locked_index(lock, 1);
2024         clean = merge_recursive(o, head_commit, next_commit, ca,
2025                         result);
2026         if (active_cache_changed &&
2027             write_locked_index(&the_index, lock, COMMIT_LOCK))
2028                 return error(_("Unable to write index."));
2029
2030         return clean ? 0 : 1;
2031 }
2032
2033 static void merge_recursive_config(struct merge_options *o)
2034 {
2035         git_config_get_int("merge.verbosity", &o->verbosity);
2036         git_config_get_int("diff.renamelimit", &o->diff_rename_limit);
2037         git_config_get_int("merge.renamelimit", &o->merge_rename_limit);
2038         git_config(git_xmerge_config, NULL);
2039 }
2040
2041 void init_merge_options(struct merge_options *o)
2042 {
2043         memset(o, 0, sizeof(struct merge_options));
2044         o->verbosity = 2;
2045         o->buffer_output = 1;
2046         o->diff_rename_limit = -1;
2047         o->merge_rename_limit = -1;
2048         o->renormalize = 0;
2049         o->detect_rename = 1;
2050         merge_recursive_config(o);
2051         if (getenv("GIT_MERGE_VERBOSITY"))
2052                 o->verbosity =
2053                         strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
2054         if (o->verbosity >= 5)
2055                 o->buffer_output = 0;
2056         strbuf_init(&o->obuf, 0);
2057         string_list_init(&o->current_file_set, 1);
2058         string_list_init(&o->current_directory_set, 1);
2059         string_list_init(&o->df_conflict_file_set, 1);
2060 }
2061
2062 int parse_merge_opt(struct merge_options *o, const char *s)
2063 {
2064         const char *arg;
2065
2066         if (!s || !*s)
2067                 return -1;
2068         if (!strcmp(s, "ours"))
2069                 o->recursive_variant = MERGE_RECURSIVE_OURS;
2070         else if (!strcmp(s, "theirs"))
2071                 o->recursive_variant = MERGE_RECURSIVE_THEIRS;
2072         else if (!strcmp(s, "subtree"))
2073                 o->subtree_shift = "";
2074         else if (skip_prefix(s, "subtree=", &arg))
2075                 o->subtree_shift = arg;
2076         else if (!strcmp(s, "patience"))
2077                 o->xdl_opts = DIFF_WITH_ALG(o, PATIENCE_DIFF);
2078         else if (!strcmp(s, "histogram"))
2079                 o->xdl_opts = DIFF_WITH_ALG(o, HISTOGRAM_DIFF);
2080         else if (skip_prefix(s, "diff-algorithm=", &arg)) {
2081                 long value = parse_algorithm_value(arg);
2082                 if (value < 0)
2083                         return -1;
2084                 /* clear out previous settings */
2085                 DIFF_XDL_CLR(o, NEED_MINIMAL);
2086                 o->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
2087                 o->xdl_opts |= value;
2088         }
2089         else if (!strcmp(s, "ignore-space-change"))
2090                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_CHANGE;
2091         else if (!strcmp(s, "ignore-all-space"))
2092                 o->xdl_opts |= XDF_IGNORE_WHITESPACE;
2093         else if (!strcmp(s, "ignore-space-at-eol"))
2094                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_AT_EOL;
2095         else if (!strcmp(s, "renormalize"))
2096                 o->renormalize = 1;
2097         else if (!strcmp(s, "no-renormalize"))
2098                 o->renormalize = 0;
2099         else if (!strcmp(s, "no-renames"))
2100                 o->detect_rename = 0;
2101         else if (!strcmp(s, "find-renames")) {
2102                 o->detect_rename = 1;
2103                 o->rename_score = 0;
2104         }
2105         else if (skip_prefix(s, "find-renames=", &arg) ||
2106                  skip_prefix(s, "rename-threshold=", &arg)) {
2107                 if ((o->rename_score = parse_rename_score(&arg)) == -1 || *arg != 0)
2108                         return -1;
2109                 o->detect_rename = 1;
2110         }
2111         else
2112                 return -1;
2113         return 0;
2114 }