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         unsigned char shifted[20];
  30
  31         if (!*subtree_shift) {
  32                 shift_tree(one->object.sha1, two->object.sha1, shifted, 0);
  33         } else {
  34                 shift_tree_by(one->object.sha1, two->object.sha1, shifted,
  35                               subtree_shift);
  36         }
  37         if (!hashcmp(two->object.sha1, shifted))
  38                 return two;
  39         return lookup_tree(shifted);
  40 }
  41
  42 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  43 {
  44         struct commit *commit = alloc_commit_node();
  45         struct merge_remote_desc *desc = xmalloc(sizeof(*desc));
  46
  47         desc->name = comment;
  48         desc->obj = (struct object *)commit;
  49         commit->tree = tree;
  50         commit->util = desc;
  51         commit->object.parsed = 1;
  52         return commit;
  53 }
  54
  55 /*
  56  * Since we use get_tree_entry(), which does not put the read object into
  57  * the object pool, we cannot rely on a == b.
  58  */
  59 static int sha_eq(const unsigned char *a, const unsigned char *b)
  60 {
  61         if (!a && !b)
  62                 return 2;
  63         return a && b && hashcmp(a, b) == 0;
  64 }
  65
  66 enum rename_type {
  67         RENAME_NORMAL = 0,
  68         RENAME_DELETE,
  69         RENAME_ONE_FILE_TO_ONE,
  70         RENAME_ONE_FILE_TO_TWO,
  71         RENAME_TWO_FILES_TO_ONE
  72 };
  73
  74 struct rename_conflict_info {
  75         enum rename_type rename_type;
  76         struct diff_filepair *pair1;
  77         struct diff_filepair *pair2;
  78         const char *branch1;
  79         const char *branch2;
  80         struct stage_data *dst_entry1;
  81         struct stage_data *dst_entry2;
  82         struct diff_filespec ren1_other;
  83         struct diff_filespec ren2_other;
  84 };
  85
  86 /*
  87  * Since we want to write the index eventually, we cannot reuse the index
  88  * for these (temporary) data.
  89  */
  90 struct stage_data {
  91         struct {
  92                 unsigned mode;
  93                 unsigned char sha[20];
  94         } stages[4];
  95         struct rename_conflict_info *rename_conflict_info;
  96         unsigned processed:1;
  97 };
  98
  99 static inline void setup_rename_conflict_info(enum rename_type rename_type,
 100                                               struct diff_filepair *pair1,
 101                                               struct diff_filepair *pair2,
 102                                               const char *branch1,
 103                                               const char *branch2,
 104                                               struct stage_data *dst_entry1,
 105                                               struct stage_data *dst_entry2,
 106                                               struct merge_options *o,
 107                                               struct stage_data *src_entry1,
 108                                               struct stage_data *src_entry2)
 109 {
 110         struct rename_conflict_info *ci = xcalloc(1, sizeof(struct rename_conflict_info));
 111         ci->rename_type = rename_type;
 112         ci->pair1 = pair1;
 113         ci->branch1 = branch1;
 114         ci->branch2 = branch2;
 115
 116         ci->dst_entry1 = dst_entry1;
 117         dst_entry1->rename_conflict_info = ci;
 118         dst_entry1->processed = 0;
 119
 120         assert(!pair2 == !dst_entry2);
 121         if (dst_entry2) {
 122                 ci->dst_entry2 = dst_entry2;
 123                 ci->pair2 = pair2;
 124                 dst_entry2->rename_conflict_info = ci;
 125         }
 126
 127         if (rename_type == RENAME_TWO_FILES_TO_ONE) {
 128                 /*
 129                  * For each rename, there could have been
 130                  * modifications on the side of history where that
 131                  * file was not renamed.
 132                  */
 133                 int ostage1 = o->branch1 == branch1 ? 3 : 2;
 134                 int ostage2 = ostage1 ^ 1;
 135
 136                 ci->ren1_other.path = pair1->one->path;
 137                 hashcpy(ci->ren1_other.sha1, src_entry1->stages[ostage1].sha);
 138                 ci->ren1_other.mode = src_entry1->stages[ostage1].mode;
 139
 140                 ci->ren2_other.path = pair2->one->path;
 141                 hashcpy(ci->ren2_other.sha1, src_entry2->stages[ostage2].sha);
 142                 ci->ren2_other.mode = src_entry2->stages[ostage2].mode;
 143         }
 144 }
 145
 146 static int show(struct merge_options *o, int v)
 147 {
 148         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
 149 }
 150
 151 static void flush_output(struct merge_options *o)
 152 {
 153         if (o->obuf.len) {
 154                 fputs(o->obuf.buf, stdout);
 155                 strbuf_reset(&o->obuf);
 156         }
 157 }
 158
 159 __attribute__((format (printf, 3, 4)))
 160 static void output(struct merge_options *o, int v, const char *fmt, ...)
 161 {
 162         va_list ap;
 163
 164         if (!show(o, v))
 165                 return;
 166
 167         strbuf_addchars(&o->obuf, ' ', o->call_depth * 2);
 168
 169         va_start(ap, fmt);
 170         strbuf_vaddf(&o->obuf, fmt, ap);
 171         va_end(ap);
 172
 173         strbuf_addch(&o->obuf, '\n');
 174         if (!o->buffer_output)
 175                 flush_output(o);
 176 }
 177
 178 static void output_commit_title(struct merge_options *o, struct commit *commit)
 179 {
 180         int i;
 181         flush_output(o);
 182         for (i = o->call_depth; i--;)
 183                 fputs("  ", stdout);
 184         if (commit->util)
 185                 printf("virtual %s\n", merge_remote_util(commit)->name);
 186         else {
 187                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 188                 if (parse_commit(commit) != 0)
 189                         printf(_("(bad commit)\n"));
 190                 else {
 191                         const char *title;
 192                         const char *msg = get_commit_buffer(commit, NULL);
 193                         int len = find_commit_subject(msg, &title);
 194                         if (len)
 195                                 printf("%.*s\n", len, title);
 196                         unuse_commit_buffer(commit, msg);
 197                 }
 198         }
 199 }
 200
 201 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 202                 const char *path, int stage, int refresh, int options)
 203 {
 204         struct cache_entry *ce;
 205         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage,
 206                               (refresh ? (CE_MATCH_REFRESH |
 207                                           CE_MATCH_IGNORE_MISSING) : 0 ));
 208         if (!ce)
 209                 return error(_("addinfo_cache failed for path '%s'"), path);
 210         return add_cache_entry(ce, options);
 211 }
 212
 213 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 214 {
 215         parse_tree(tree);
 216         init_tree_desc(desc, tree->buffer, tree->size);
 217 }
 218
 219 static int git_merge_trees(int index_only,
 220                            struct tree *common,
 221                            struct tree *head,
 222                            struct tree *merge)
 223 {
 224         int rc;
 225         struct tree_desc t[3];
 226         struct unpack_trees_options opts;
 227
 228         memset(&opts, 0, sizeof(opts));
 229         if (index_only)
 230                 opts.index_only = 1;
 231         else
 232                 opts.update = 1;
 233         opts.merge = 1;
 234         opts.head_idx = 2;
 235         opts.fn = threeway_merge;
 236         opts.src_index = &the_index;
 237         opts.dst_index = &the_index;
 238         setup_unpack_trees_porcelain(&opts, "merge");
 239
 240         init_tree_desc_from_tree(t+0, common);
 241         init_tree_desc_from_tree(t+1, head);
 242         init_tree_desc_from_tree(t+2, merge);
 243
 244         rc = unpack_trees(3, t, &opts);
 245         cache_tree_free(&active_cache_tree);
 246         return rc;
 247 }
 248
 249 struct tree *write_tree_from_memory(struct merge_options *o)
 250 {
 251         struct tree *result = NULL;
 252
 253         if (unmerged_cache()) {
 254                 int i;
 255                 fprintf(stderr, "BUG: There are unmerged index entries:\n");
 256                 for (i = 0; i < active_nr; i++) {
 257                         const struct cache_entry *ce = active_cache[i];
 258                         if (ce_stage(ce))
 259                                 fprintf(stderr, "BUG: %d %.*s\n", ce_stage(ce),
 260                                         (int)ce_namelen(ce), ce->name);
 261                 }
 262                 die("Bug in merge-recursive.c");
 263         }
 264
 265         if (!active_cache_tree)
 266                 active_cache_tree = cache_tree();
 267
 268         if (!cache_tree_fully_valid(active_cache_tree) &&
 269             cache_tree_update(&the_index, 0) < 0)
 270                 die(_("error building trees"));
 271
 272         result = lookup_tree(active_cache_tree->sha1);
 273
 274         return result;
 275 }
 276
 277 static int save_files_dirs(const unsigned char *sha1,
 278                 struct strbuf *base, const char *path,
 279                 unsigned int mode, int stage, void *context)
 280 {
 281         int baselen = base->len;
 282         struct merge_options *o = context;
 283
 284         strbuf_addstr(base, path);
 285
 286         if (S_ISDIR(mode))
 287                 string_list_insert(&o->current_directory_set, base->buf);
 288         else
 289                 string_list_insert(&o->current_file_set, base->buf);
 290
 291         strbuf_setlen(base, baselen);
 292         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
 293 }
 294
 295 static int get_files_dirs(struct merge_options *o, struct tree *tree)
 296 {
 297         int n;
 298         struct pathspec match_all;
 299         memset(&match_all, 0, sizeof(match_all));
 300         if (read_tree_recursive(tree, "", 0, 0, &match_all, save_files_dirs, o))
 301                 return 0;
 302         n = o->current_file_set.nr + o->current_directory_set.nr;
 303         return n;
 304 }
 305
 306 /*
 307  * Returns an index_entry instance which doesn't have to correspond to
 308  * a real cache entry in Git's index.
 309  */
 310 static struct stage_data *insert_stage_data(const char *path,
 311                 struct tree *o, struct tree *a, struct tree *b,
 312                 struct string_list *entries)
 313 {
 314         struct string_list_item *item;
 315         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 316         get_tree_entry(o->object.sha1, path,
 317                         e->stages[1].sha, &e->stages[1].mode);
 318         get_tree_entry(a->object.sha1, path,
 319                         e->stages[2].sha, &e->stages[2].mode);
 320         get_tree_entry(b->object.sha1, path,
 321                         e->stages[3].sha, &e->stages[3].mode);
 322         item = string_list_insert(entries, path);
 323         item->util = e;
 324         return e;
 325 }
 326
 327 /*
 328  * Create a dictionary mapping file names to stage_data objects. The
 329  * dictionary contains one entry for every path with a non-zero stage entry.
 330  */
 331 static struct string_list *get_unmerged(void)
 332 {
 333         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
 334         int i;
 335
 336         unmerged->strdup_strings = 1;
 337
 338         for (i = 0; i < active_nr; i++) {
 339                 struct string_list_item *item;
 340                 struct stage_data *e;
 341                 const struct cache_entry *ce = active_cache[i];
 342                 if (!ce_stage(ce))
 343                         continue;
 344
 345                 item = string_list_lookup(unmerged, ce->name);
 346                 if (!item) {
 347                         item = string_list_insert(unmerged, ce->name);
 348                         item->util = xcalloc(1, sizeof(struct stage_data));
 349                 }
 350                 e = item->util;
 351                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
 352                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 353         }
 354
 355         return unmerged;
 356 }
 357
 358 static int string_list_df_name_compare(const void *a, const void *b)
 359 {
 360         const struct string_list_item *one = a;
 361         const struct string_list_item *two = b;
 362         int onelen = strlen(one->string);
 363         int twolen = strlen(two->string);
 364         /*
 365          * Here we only care that entries for D/F conflicts are
 366          * adjacent, in particular with the file of the D/F conflict
 367          * appearing before files below the corresponding directory.
 368          * The order of the rest of the list is irrelevant for us.
 369          *
 370          * To achieve this, we sort with df_name_compare and provide
 371          * the mode S_IFDIR so that D/F conflicts will sort correctly.
 372          * We use the mode S_IFDIR for everything else for simplicity,
 373          * since in other cases any changes in their order due to
 374          * sorting cause no problems for us.
 375          */
 376         int cmp = df_name_compare(one->string, onelen, S_IFDIR,
 377                                   two->string, twolen, S_IFDIR);
 378         /*
 379          * Now that 'foo' and 'foo/bar' compare equal, we have to make sure
 380          * that 'foo' comes before 'foo/bar'.
 381          */
 382         if (cmp)
 383                 return cmp;
 384         return onelen - twolen;
 385 }
 386
 387 static void record_df_conflict_files(struct merge_options *o,
 388                                      struct string_list *entries)
 389 {
 390         /* If there is a D/F conflict and the file for such a conflict
 391          * currently exist in the working tree, we want to allow it to be
 392          * removed to make room for the corresponding directory if needed.
 393          * The files underneath the directories of such D/F conflicts will
 394          * be processed before the corresponding file involved in the D/F
 395          * conflict.  If the D/F directory ends up being removed by the
 396          * merge, then we won't have to touch the D/F file.  If the D/F
 397          * directory needs to be written to the working copy, then the D/F
 398          * file will simply be removed (in make_room_for_path()) to make
 399          * room for the necessary paths.  Note that if both the directory
 400          * and the file need to be present, then the D/F file will be
 401          * reinstated with a new unique name at the time it is processed.
 402          */
 403         struct string_list df_sorted_entries;
 404         const char *last_file = NULL;
 405         int last_len = 0;
 406         int i;
 407
 408         /*
 409          * If we're merging merge-bases, we don't want to bother with
 410          * any working directory changes.
 411          */
 412         if (o->call_depth)
 413                 return;
 414
 415         /* Ensure D/F conflicts are adjacent in the entries list. */
 416         memset(&df_sorted_entries, 0, sizeof(struct string_list));
 417         for (i = 0; i < entries->nr; i++) {
 418                 struct string_list_item *next = &entries->items[i];
 419                 string_list_append(&df_sorted_entries, next->string)->util =
 420                                    next->util;
 421         }
 422         qsort(df_sorted_entries.items, entries->nr, sizeof(*entries->items),
 423               string_list_df_name_compare);
 424
 425         string_list_clear(&o->df_conflict_file_set, 1);
 426         for (i = 0; i < df_sorted_entries.nr; i++) {
 427                 const char *path = df_sorted_entries.items[i].string;
 428                 int len = strlen(path);
 429                 struct stage_data *e = df_sorted_entries.items[i].util;
 430
 431                 /*
 432                  * Check if last_file & path correspond to a D/F conflict;
 433                  * i.e. whether path is last_file+'/'+<something>.
 434                  * If so, record that it's okay to remove last_file to make
 435                  * room for path and friends if needed.
 436                  */
 437                 if (last_file &&
 438                     len > last_len &&
 439                     memcmp(path, last_file, last_len) == 0 &&
 440                     path[last_len] == '/') {
 441                         string_list_insert(&o->df_conflict_file_set, last_file);
 442                 }
 443
 444                 /*
 445                  * Determine whether path could exist as a file in the
 446                  * working directory as a possible D/F conflict.  This
 447                  * will only occur when it exists in stage 2 as a
 448                  * file.
 449                  */
 450                 if (S_ISREG(e->stages[2].mode) || S_ISLNK(e->stages[2].mode)) {
 451                         last_file = path;
 452                         last_len = len;
 453                 } else {
 454                         last_file = NULL;
 455                 }
 456         }
 457         string_list_clear(&df_sorted_entries, 0);
 458 }
 459
 460 struct rename {
 461         struct diff_filepair *pair;
 462         struct stage_data *src_entry;
 463         struct stage_data *dst_entry;
 464         unsigned processed:1;
 465 };
 466
 467 /*
 468  * Get information of all renames which occurred between 'o_tree' and
 469  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 470  * 'b_tree') to be able to associate the correct cache entries with
 471  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 472  */
 473 static struct string_list *get_renames(struct merge_options *o,
 474                                        struct tree *tree,
 475                                        struct tree *o_tree,
 476                                        struct tree *a_tree,
 477                                        struct tree *b_tree,
 478                                        struct string_list *entries)
 479 {
 480         int i;
 481         struct string_list *renames;
 482         struct diff_options opts;
 483
 484         renames = xcalloc(1, sizeof(struct string_list));
 485         diff_setup(&opts);
 486         DIFF_OPT_SET(&opts, RECURSIVE);
 487         DIFF_OPT_CLR(&opts, RENAME_EMPTY);
 488         opts.detect_rename = DIFF_DETECT_RENAME;
 489         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 490                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 491                             1000;
 492         opts.rename_score = o->rename_score;
 493         opts.show_rename_progress = o->show_rename_progress;
 494         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 495         diff_setup_done(&opts);
 496         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 497         diffcore_std(&opts);
 498         if (opts.needed_rename_limit > o->needed_rename_limit)
 499                 o->needed_rename_limit = opts.needed_rename_limit;
 500         for (i = 0; i < diff_queued_diff.nr; ++i) {
 501                 struct string_list_item *item;
 502                 struct rename *re;
 503                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 504                 if (pair->status != 'R') {
 505                         diff_free_filepair(pair);
 506                         continue;
 507                 }
 508                 re = xmalloc(sizeof(*re));
 509                 re->processed = 0;
 510                 re->pair = pair;
 511                 item = string_list_lookup(entries, re->pair->one->path);
 512                 if (!item)
 513                         re->src_entry = insert_stage_data(re->pair->one->path,
 514                                         o_tree, a_tree, b_tree, entries);
 515                 else
 516                         re->src_entry = item->util;
 517
 518                 item = string_list_lookup(entries, re->pair->two->path);
 519                 if (!item)
 520                         re->dst_entry = insert_stage_data(re->pair->two->path,
 521                                         o_tree, a_tree, b_tree, entries);
 522                 else
 523                         re->dst_entry = item->util;
 524                 item = string_list_insert(renames, pair->one->path);
 525                 item->util = re;
 526         }
 527         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 528         diff_queued_diff.nr = 0;
 529         diff_flush(&opts);
 530         return renames;
 531 }
 532
 533 static int update_stages(const char *path, const struct diff_filespec *o,
 534                          const struct diff_filespec *a,
 535                          const struct diff_filespec *b)
 536 {
 537
 538         /*
 539          * NOTE: It is usually a bad idea to call update_stages on a path
 540          * before calling update_file on that same path, since it can
 541          * sometimes lead to spurious "refusing to lose untracked file..."
 542          * messages from update_file (via make_room_for path via
 543          * would_lose_untracked).  Instead, reverse the order of the calls
 544          * (executing update_file first and then update_stages).
 545          */
 546         int clear = 1;
 547         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_SKIP_DFCHECK;
 548         if (clear)
 549                 if (remove_file_from_cache(path))
 550                         return -1;
 551         if (o)
 552                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 553                         return -1;
 554         if (a)
 555                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 556                         return -1;
 557         if (b)
 558                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 559                         return -1;
 560         return 0;
 561 }
 562
 563 static void update_entry(struct stage_data *entry,
 564                          struct diff_filespec *o,
 565                          struct diff_filespec *a,
 566                          struct diff_filespec *b)
 567 {
 568         entry->processed = 0;
 569         entry->stages[1].mode = o->mode;
 570         entry->stages[2].mode = a->mode;
 571         entry->stages[3].mode = b->mode;
 572         hashcpy(entry->stages[1].sha, o->sha1);
 573         hashcpy(entry->stages[2].sha, a->sha1);
 574         hashcpy(entry->stages[3].sha, b->sha1);
 575 }
 576
 577 static int remove_file(struct merge_options *o, int clean,
 578                        const char *path, int no_wd)
 579 {
 580         int update_cache = o->call_depth || clean;
 581         int update_working_directory = !o->call_depth && !no_wd;
 582
 583         if (update_cache) {
 584                 if (remove_file_from_cache(path))
 585                         return -1;
 586         }
 587         if (update_working_directory) {
 588                 if (ignore_case) {
 589                         struct cache_entry *ce;
 590                         ce = cache_file_exists(path, strlen(path), ignore_case);
 591                         if (ce && ce_stage(ce) == 0)
 592                                 return 0;
 593                 }
 594                 if (remove_path(path))
 595                         return -1;
 596         }
 597         return 0;
 598 }
 599
 600 /* add a string to a strbuf, but converting "/" to "_" */
 601 static void add_flattened_path(struct strbuf *out, const char *s)
 602 {
 603         size_t i = out->len;
 604         strbuf_addstr(out, s);
 605         for (; i < out->len; i++)
 606                 if (out->buf[i] == '/')
 607                         out->buf[i] = '_';
 608 }
 609
 610 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
 611 {
 612         struct strbuf newpath = STRBUF_INIT;
 613         int suffix = 0;
 614         struct stat st;
 615         size_t base_len;
 616
 617         strbuf_addf(&newpath, "%s~", path);
 618         add_flattened_path(&newpath, branch);
 619
 620         base_len = newpath.len;
 621         while (string_list_has_string(&o->current_file_set, newpath.buf) ||
 622                string_list_has_string(&o->current_directory_set, newpath.buf) ||
 623                lstat(newpath.buf, &st) == 0) {
 624                 strbuf_setlen(&newpath, base_len);
 625                 strbuf_addf(&newpath, "_%d", suffix++);
 626         }
 627
 628         string_list_insert(&o->current_file_set, newpath.buf);
 629         return strbuf_detach(&newpath, NULL);
 630 }
 631
 632 static int dir_in_way(const char *path, int check_working_copy)
 633 {
 634         int pos, pathlen = strlen(path);
 635         char *dirpath = xmalloc(pathlen + 2);
 636         struct stat st;
 637
 638         strcpy(dirpath, path);
 639         dirpath[pathlen] = '/';
 640         dirpath[pathlen+1] = '\0';
 641
 642         pos = cache_name_pos(dirpath, pathlen+1);
 643
 644         if (pos < 0)
 645                 pos = -1 - pos;
 646         if (pos < active_nr &&
 647             !strncmp(dirpath, active_cache[pos]->name, pathlen+1)) {
 648                 free(dirpath);
 649                 return 1;
 650         }
 651
 652         free(dirpath);
 653         return check_working_copy && !lstat(path, &st) && S_ISDIR(st.st_mode);
 654 }
 655
 656 static int was_tracked(const char *path)
 657 {
 658         int pos = cache_name_pos(path, strlen(path));
 659
 660         if (pos < 0)
 661                 pos = -1 - pos;
 662         while (pos < active_nr &&
 663                !strcmp(path, active_cache[pos]->name)) {
 664                 /*
 665                  * If stage #0, it is definitely tracked.
 666                  * If it has stage #2 then it was tracked
 667                  * before this merge started.  All other
 668                  * cases the path was not tracked.
 669                  */
 670                 switch (ce_stage(active_cache[pos])) {
 671                 case 0:
 672                 case 2:
 673                         return 1;
 674                 }
 675                 pos++;
 676         }
 677         return 0;
 678 }
 679
 680 static int would_lose_untracked(const char *path)
 681 {
 682         return !was_tracked(path) && file_exists(path);
 683 }
 684
 685 static int make_room_for_path(struct merge_options *o, const char *path)
 686 {
 687         int status, i;
 688         const char *msg = _("failed to create path '%s'%s");
 689
 690         /* Unlink any D/F conflict files that are in the way */
 691         for (i = 0; i < o->df_conflict_file_set.nr; i++) {
 692                 const char *df_path = o->df_conflict_file_set.items[i].string;
 693                 size_t pathlen = strlen(path);
 694                 size_t df_pathlen = strlen(df_path);
 695                 if (df_pathlen < pathlen &&
 696                     path[df_pathlen] == '/' &&
 697                     strncmp(path, df_path, df_pathlen) == 0) {
 698                         output(o, 3,
 699                                _("Removing %s to make room for subdirectory\n"),
 700                                df_path);
 701                         unlink(df_path);
 702                         unsorted_string_list_delete_item(&o->df_conflict_file_set,
 703                                                          i, 0);
 704                         break;
 705                 }
 706         }
 707
 708         /* Make sure leading directories are created */
 709         status = safe_create_leading_directories_const(path);
 710         if (status) {
 711                 if (status == SCLD_EXISTS) {
 712                         /* something else exists */
 713                         error(msg, path, _(": perhaps a D/F conflict?"));
 714                         return -1;
 715                 }
 716                 die(msg, path, "");
 717         }
 718
 719         /*
 720          * Do not unlink a file in the work tree if we are not
 721          * tracking it.
 722          */
 723         if (would_lose_untracked(path))
 724                 return error(_("refusing to lose untracked file at '%s'"),
 725                              path);
 726
 727         /* Successful unlink is good.. */
 728         if (!unlink(path))
 729                 return 0;
 730         /* .. and so is no existing file */
 731         if (errno == ENOENT)
 732                 return 0;
 733         /* .. but not some other error (who really cares what?) */
 734         return error(msg, path, _(": perhaps a D/F conflict?"));
 735 }
 736
 737 static void update_file_flags(struct merge_options *o,
 738                               const unsigned char *sha,
 739                               unsigned mode,
 740                               const char *path,
 741                               int update_cache,
 742                               int update_wd)
 743 {
 744         if (o->call_depth)
 745                 update_wd = 0;
 746
 747         if (update_wd) {
 748                 enum object_type type;
 749                 void *buf;
 750                 unsigned long size;
 751
 752                 if (S_ISGITLINK(mode)) {
 753                         /*
 754                          * We may later decide to recursively descend into
 755                          * the submodule directory and update its index
 756                          * and/or work tree, but we do not do that now.
 757                          */
 758                         update_wd = 0;
 759                         goto update_index;
 760                 }
 761
 762                 buf = read_sha1_file(sha, &type, &size);
 763                 if (!buf)
 764                         die(_("cannot read object %s '%s'"), sha1_to_hex(sha), path);
 765                 if (type != OBJ_BLOB)
 766                         die(_("blob expected for %s '%s'"), sha1_to_hex(sha), path);
 767                 if (S_ISREG(mode)) {
 768                         struct strbuf strbuf = STRBUF_INIT;
 769                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
 770                                 free(buf);
 771                                 size = strbuf.len;
 772                                 buf = strbuf_detach(&strbuf, NULL);
 773                         }
 774                 }
 775
 776                 if (make_room_for_path(o, path) < 0) {
 777                         update_wd = 0;
 778                         free(buf);
 779                         goto update_index;
 780                 }
 781                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 782                         int fd;
 783                         if (mode & 0100)
 784                                 mode = 0777;
 785                         else
 786                                 mode = 0666;
 787                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 788                         if (fd < 0)
 789                                 die_errno(_("failed to open '%s'"), path);
 790                         write_in_full(fd, buf, size);
 791                         close(fd);
 792                 } else if (S_ISLNK(mode)) {
 793                         char *lnk = xmemdupz(buf, size);
 794                         safe_create_leading_directories_const(path);
 795                         unlink(path);
 796                         if (symlink(lnk, path))
 797                                 die_errno(_("failed to symlink '%s'"), path);
 798                         free(lnk);
 799                 } else
 800                         die(_("do not know what to do with %06o %s '%s'"),
 801                             mode, sha1_to_hex(sha), path);
 802                 free(buf);
 803         }
 804  update_index:
 805         if (update_cache)
 806                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 807 }
 808
 809 static void update_file(struct merge_options *o,
 810                         int clean,
 811                         const unsigned char *sha,
 812                         unsigned mode,
 813                         const char *path)
 814 {
 815         update_file_flags(o, sha, mode, path, o->call_depth || clean, !o->call_depth);
 816 }
 817
 818 /* Low level file merging, update and removal */
 819
 820 struct merge_file_info {
 821         unsigned char sha[20];
 822         unsigned mode;
 823         unsigned clean:1,
 824                  merge:1;
 825 };
 826
 827 static int merge_3way(struct merge_options *o,
 828                       mmbuffer_t *result_buf,
 829                       const struct diff_filespec *one,
 830                       const struct diff_filespec *a,
 831                       const struct diff_filespec *b,
 832                       const char *branch1,
 833                       const char *branch2)
 834 {
 835         mmfile_t orig, src1, src2;
 836         struct ll_merge_options ll_opts = {0};
 837         char *base_name, *name1, *name2;
 838         int merge_status;
 839
 840         ll_opts.renormalize = o->renormalize;
 841         ll_opts.xdl_opts = o->xdl_opts;
 842
 843         if (o->call_depth) {
 844                 ll_opts.virtual_ancestor = 1;
 845                 ll_opts.variant = 0;
 846         } else {
 847                 switch (o->recursive_variant) {
 848                 case MERGE_RECURSIVE_OURS:
 849                         ll_opts.variant = XDL_MERGE_FAVOR_OURS;
 850                         break;
 851                 case MERGE_RECURSIVE_THEIRS:
 852                         ll_opts.variant = XDL_MERGE_FAVOR_THEIRS;
 853                         break;
 854                 default:
 855                         ll_opts.variant = 0;
 856                         break;
 857                 }
 858         }
 859
 860         if (strcmp(a->path, b->path) ||
 861             (o->ancestor != NULL && strcmp(a->path, one->path) != 0)) {
 862                 base_name = o->ancestor == NULL ? NULL :
 863                         mkpathdup("%s:%s", o->ancestor, one->path);
 864                 name1 = mkpathdup("%s:%s", branch1, a->path);
 865                 name2 = mkpathdup("%s:%s", branch2, b->path);
 866         } else {
 867                 base_name = o->ancestor == NULL ? NULL :
 868                         mkpathdup("%s", o->ancestor);
 869                 name1 = mkpathdup("%s", branch1);
 870                 name2 = mkpathdup("%s", branch2);
 871         }
 872
 873         read_mmblob(&orig, one->sha1);
 874         read_mmblob(&src1, a->sha1);
 875         read_mmblob(&src2, b->sha1);
 876
 877         merge_status = ll_merge(result_buf, a->path, &orig, base_name,
 878                                 &src1, name1, &src2, name2, &ll_opts);
 879
 880         free(base_name);
 881         free(name1);
 882         free(name2);
 883         free(orig.ptr);
 884         free(src1.ptr);
 885         free(src2.ptr);
 886         return merge_status;
 887 }
 888
 889 static struct merge_file_info merge_file_1(struct merge_options *o,
 890                                            const struct diff_filespec *one,
 891                                            const struct diff_filespec *a,
 892                                            const struct diff_filespec *b,
 893                                            const char *branch1,
 894                                            const char *branch2)
 895 {
 896         struct merge_file_info result;
 897         result.merge = 0;
 898         result.clean = 1;
 899
 900         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 901                 result.clean = 0;
 902                 if (S_ISREG(a->mode)) {
 903                         result.mode = a->mode;
 904                         hashcpy(result.sha, a->sha1);
 905                 } else {
 906                         result.mode = b->mode;
 907                         hashcpy(result.sha, b->sha1);
 908                 }
 909         } else {
 910                 if (!sha_eq(a->sha1, one->sha1) && !sha_eq(b->sha1, one->sha1))
 911                         result.merge = 1;
 912
 913                 /*
 914                  * Merge modes
 915                  */
 916                 if (a->mode == b->mode || a->mode == one->mode)
 917                         result.mode = b->mode;
 918                 else {
 919                         result.mode = a->mode;
 920                         if (b->mode != one->mode) {
 921                                 result.clean = 0;
 922                                 result.merge = 1;
 923                         }
 924                 }
 925
 926                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, one->sha1))
 927                         hashcpy(result.sha, b->sha1);
 928                 else if (sha_eq(b->sha1, one->sha1))
 929                         hashcpy(result.sha, a->sha1);
 930                 else if (S_ISREG(a->mode)) {
 931                         mmbuffer_t result_buf;
 932                         int merge_status;
 933
 934                         merge_status = merge_3way(o, &result_buf, one, a, b,
 935                                                   branch1, branch2);
 936
 937                         if ((merge_status < 0) || !result_buf.ptr)
 938                                 die(_("Failed to execute internal merge"));
 939
 940                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 941                                             blob_type, result.sha))
 942                                 die(_("Unable to add %s to database"),
 943                                     a->path);
 944
 945                         free(result_buf.ptr);
 946                         result.clean = (merge_status == 0);
 947                 } else if (S_ISGITLINK(a->mode)) {
 948                         result.clean = merge_submodule(result.sha,
 949                                                        one->path, one->sha1,
 950                                                        a->sha1, b->sha1,
 951                                                        !o->call_depth);
 952                 } else if (S_ISLNK(a->mode)) {
 953                         hashcpy(result.sha, a->sha1);
 954
 955                         if (!sha_eq(a->sha1, b->sha1))
 956                                 result.clean = 0;
 957                 } else {
 958                         die(_("unsupported object type in the tree"));
 959                 }
 960         }
 961
 962         return result;
 963 }
 964
 965 static struct merge_file_info
 966 merge_file_special_markers(struct merge_options *o,
 967                            const struct diff_filespec *one,
 968                            const struct diff_filespec *a,
 969                            const struct diff_filespec *b,
 970                            const char *branch1,
 971                            const char *filename1,
 972                            const char *branch2,
 973                            const char *filename2)
 974 {
 975         char *side1 = NULL;
 976         char *side2 = NULL;
 977         struct merge_file_info mfi;
 978
 979         if (filename1)
 980                 side1 = xstrfmt("%s:%s", branch1, filename1);
 981         if (filename2)
 982                 side2 = xstrfmt("%s:%s", branch2, filename2);
 983
 984         mfi = merge_file_1(o, one, a, b,
 985                            side1 ? side1 : branch1, side2 ? side2 : branch2);
 986         free(side1);
 987         free(side2);
 988         return mfi;
 989 }
 990
 991 static struct merge_file_info merge_file_one(struct merge_options *o,
 992                                          const char *path,
 993                                          const unsigned char *o_sha, int o_mode,
 994                                          const unsigned char *a_sha, int a_mode,
 995                                          const unsigned char *b_sha, int b_mode,
 996                                          const char *branch1,
 997                                          const char *branch2)
 998 {
 999         struct diff_filespec one, a, b;
1000
1001         one.path = a.path = b.path = (char *)path;
1002         hashcpy(one.sha1, o_sha);
1003         one.mode = o_mode;
1004         hashcpy(a.sha1, a_sha);
1005         a.mode = a_mode;
1006         hashcpy(b.sha1, b_sha);
1007         b.mode = b_mode;
1008         return merge_file_1(o, &one, &a, &b, branch1, branch2);
1009 }
1010
1011 static void handle_change_delete(struct merge_options *o,
1012                                  const char *path,
1013                                  const unsigned char *o_sha, int o_mode,
1014                                  const unsigned char *a_sha, int a_mode,
1015                                  const unsigned char *b_sha, int b_mode,
1016                                  const char *change, const char *change_past)
1017 {
1018         char *renamed = NULL;
1019         if (dir_in_way(path, !o->call_depth)) {
1020                 renamed = unique_path(o, path, a_sha ? o->branch1 : o->branch2);
1021         }
1022
1023         if (o->call_depth) {
1024                 /*
1025                  * We cannot arbitrarily accept either a_sha or b_sha as
1026                  * correct; since there is no true "middle point" between
1027                  * them, simply reuse the base version for virtual merge base.
1028                  */
1029                 remove_file_from_cache(path);
1030                 update_file(o, 0, o_sha, o_mode, renamed ? renamed : path);
1031         } else if (!a_sha) {
1032                 if (!renamed) {
1033                         output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1034                                "and %s in %s. Version %s of %s left in tree."),
1035                                change, path, o->branch1, change_past,
1036                                o->branch2, o->branch2, path);
1037                         update_file(o, 0, b_sha, b_mode, path);
1038                 } else {
1039                         output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1040                                "and %s in %s. Version %s of %s left in tree at %s."),
1041                                change, path, o->branch1, change_past,
1042                                o->branch2, o->branch2, path, renamed);
1043                         update_file(o, 0, b_sha, b_mode, renamed);
1044                 }
1045         } else {
1046                 if (!renamed) {
1047                         output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1048                                "and %s in %s. Version %s of %s left in tree."),
1049                                change, path, o->branch2, change_past,
1050                                o->branch1, o->branch1, path);
1051                 } else {
1052                         output(o, 1, _("CONFLICT (%s/delete): %s deleted in %s "
1053                                "and %s in %s. Version %s of %s left in tree at %s."),
1054                                change, path, o->branch2, change_past,
1055                                o->branch1, o->branch1, path, renamed);
1056                         update_file(o, 0, a_sha, a_mode, renamed);
1057                 }
1058                 /*
1059                  * No need to call update_file() on path when !renamed, since
1060                  * that would needlessly touch path.  We could call
1061                  * update_file_flags() with update_cache=0 and update_wd=0,
1062                  * but that's a no-op.
1063                  */
1064         }
1065         free(renamed);
1066 }
1067
1068 static void conflict_rename_delete(struct merge_options *o,
1069                                    struct diff_filepair *pair,
1070                                    const char *rename_branch,
1071                                    const char *other_branch)
1072 {
1073         const struct diff_filespec *orig = pair->one;
1074         const struct diff_filespec *dest = pair->two;
1075         const unsigned char *a_sha = NULL;
1076         const unsigned char *b_sha = NULL;
1077         int a_mode = 0;
1078         int b_mode = 0;
1079
1080         if (rename_branch == o->branch1) {
1081                 a_sha = dest->sha1;
1082                 a_mode = dest->mode;
1083         } else {
1084                 b_sha = dest->sha1;
1085                 b_mode = dest->mode;
1086         }
1087
1088         handle_change_delete(o,
1089                              o->call_depth ? orig->path : dest->path,
1090                              orig->sha1, orig->mode,
1091                              a_sha, a_mode,
1092                              b_sha, b_mode,
1093                              _("rename"), _("renamed"));
1094
1095         if (o->call_depth) {
1096                 remove_file_from_cache(dest->path);
1097         } else {
1098                 update_stages(dest->path, NULL,
1099                               rename_branch == o->branch1 ? dest : NULL,
1100                               rename_branch == o->branch1 ? NULL : dest);
1101         }
1102
1103 }
1104
1105 static struct diff_filespec *filespec_from_entry(struct diff_filespec *target,
1106                                                  struct stage_data *entry,
1107                                                  int stage)
1108 {
1109         unsigned char *sha = entry->stages[stage].sha;
1110         unsigned mode = entry->stages[stage].mode;
1111         if (mode == 0 || is_null_sha1(sha))
1112                 return NULL;
1113         hashcpy(target->sha1, sha);
1114         target->mode = mode;
1115         return target;
1116 }
1117
1118 static void handle_file(struct merge_options *o,
1119                         struct diff_filespec *rename,
1120                         int stage,
1121                         struct rename_conflict_info *ci)
1122 {
1123         char *dst_name = rename->path;
1124         struct stage_data *dst_entry;
1125         const char *cur_branch, *other_branch;
1126         struct diff_filespec other;
1127         struct diff_filespec *add;
1128
1129         if (stage == 2) {
1130                 dst_entry = ci->dst_entry1;
1131                 cur_branch = ci->branch1;
1132                 other_branch = ci->branch2;
1133         } else {
1134                 dst_entry = ci->dst_entry2;
1135                 cur_branch = ci->branch2;
1136                 other_branch = ci->branch1;
1137         }
1138
1139         add = filespec_from_entry(&other, dst_entry, stage ^ 1);
1140         if (add) {
1141                 char *add_name = unique_path(o, rename->path, other_branch);
1142                 update_file(o, 0, add->sha1, add->mode, add_name);
1143
1144                 remove_file(o, 0, rename->path, 0);
1145                 dst_name = unique_path(o, rename->path, cur_branch);
1146         } else {
1147                 if (dir_in_way(rename->path, !o->call_depth)) {
1148                         dst_name = unique_path(o, rename->path, cur_branch);
1149                         output(o, 1, _("%s is a directory in %s adding as %s instead"),
1150                                rename->path, other_branch, dst_name);
1151                 }
1152         }
1153         update_file(o, 0, rename->sha1, rename->mode, dst_name);
1154         if (stage == 2)
1155                 update_stages(rename->path, NULL, rename, add);
1156         else
1157                 update_stages(rename->path, NULL, add, rename);
1158
1159         if (dst_name != rename->path)
1160                 free(dst_name);
1161 }
1162
1163 static void conflict_rename_rename_1to2(struct merge_options *o,
1164                                         struct rename_conflict_info *ci)
1165 {
1166         /* One file was renamed in both branches, but to different names. */
1167         struct diff_filespec *one = ci->pair1->one;
1168         struct diff_filespec *a = ci->pair1->two;
1169         struct diff_filespec *b = ci->pair2->two;
1170
1171         output(o, 1, _("CONFLICT (rename/rename): "
1172                "Rename \"%s\"->\"%s\" in branch \"%s\" "
1173                "rename \"%s\"->\"%s\" in \"%s\"%s"),
1174                one->path, a->path, ci->branch1,
1175                one->path, b->path, ci->branch2,
1176                o->call_depth ? _(" (left unresolved)") : "");
1177         if (o->call_depth) {
1178                 struct merge_file_info mfi;
1179                 struct diff_filespec other;
1180                 struct diff_filespec *add;
1181                 mfi = merge_file_one(o, one->path,
1182                                  one->sha1, one->mode,
1183                                  a->sha1, a->mode,
1184                                  b->sha1, b->mode,
1185                                  ci->branch1, ci->branch2);
1186                 /*
1187                  * FIXME: For rename/add-source conflicts (if we could detect
1188                  * such), this is wrong.  We should instead find a unique
1189                  * pathname and then either rename the add-source file to that
1190                  * unique path, or use that unique path instead of src here.
1191                  */
1192                 update_file(o, 0, mfi.sha, mfi.mode, one->path);
1193
1194                 /*
1195                  * Above, we put the merged content at the merge-base's
1196                  * path.  Now we usually need to delete both a->path and
1197                  * b->path.  However, the rename on each side of the merge
1198                  * could also be involved in a rename/add conflict.  In
1199                  * such cases, we should keep the added file around,
1200                  * resolving the conflict at that path in its favor.
1201                  */
1202                 add = filespec_from_entry(&other, ci->dst_entry1, 2 ^ 1);
1203                 if (add)
1204                         update_file(o, 0, add->sha1, add->mode, a->path);
1205                 else
1206                         remove_file_from_cache(a->path);
1207                 add = filespec_from_entry(&other, ci->dst_entry2, 3 ^ 1);
1208                 if (add)
1209                         update_file(o, 0, add->sha1, add->mode, b->path);
1210                 else
1211                         remove_file_from_cache(b->path);
1212         } else {
1213                 handle_file(o, a, 2, ci);
1214                 handle_file(o, b, 3, ci);
1215         }
1216 }
1217
1218 static void conflict_rename_rename_2to1(struct merge_options *o,
1219                                         struct rename_conflict_info *ci)
1220 {
1221         /* Two files, a & b, were renamed to the same thing, c. */
1222         struct diff_filespec *a = ci->pair1->one;
1223         struct diff_filespec *b = ci->pair2->one;
1224         struct diff_filespec *c1 = ci->pair1->two;
1225         struct diff_filespec *c2 = ci->pair2->two;
1226         char *path = c1->path; /* == c2->path */
1227         struct merge_file_info mfi_c1;
1228         struct merge_file_info mfi_c2;
1229
1230         output(o, 1, _("CONFLICT (rename/rename): "
1231                "Rename %s->%s in %s. "
1232                "Rename %s->%s in %s"),
1233                a->path, c1->path, ci->branch1,
1234                b->path, c2->path, ci->branch2);
1235
1236         remove_file(o, 1, a->path, would_lose_untracked(a->path));
1237         remove_file(o, 1, b->path, would_lose_untracked(b->path));
1238
1239         mfi_c1 = merge_file_special_markers(o, a, c1, &ci->ren1_other,
1240                                             o->branch1, c1->path,
1241                                             o->branch2, ci->ren1_other.path);
1242         mfi_c2 = merge_file_special_markers(o, b, &ci->ren2_other, c2,
1243                                             o->branch1, ci->ren2_other.path,
1244                                             o->branch2, c2->path);
1245
1246         if (o->call_depth) {
1247                 /*
1248                  * If mfi_c1.clean && mfi_c2.clean, then it might make
1249                  * sense to do a two-way merge of those results.  But, I
1250                  * think in all cases, it makes sense to have the virtual
1251                  * merge base just undo the renames; they can be detected
1252                  * again later for the non-recursive merge.
1253                  */
1254                 remove_file(o, 0, path, 0);
1255                 update_file(o, 0, mfi_c1.sha, mfi_c1.mode, a->path);
1256                 update_file(o, 0, mfi_c2.sha, mfi_c2.mode, b->path);
1257         } else {
1258                 char *new_path1 = unique_path(o, path, ci->branch1);
1259                 char *new_path2 = unique_path(o, path, ci->branch2);
1260                 output(o, 1, _("Renaming %s to %s and %s to %s instead"),
1261                        a->path, new_path1, b->path, new_path2);
1262                 remove_file(o, 0, path, 0);
1263                 update_file(o, 0, mfi_c1.sha, mfi_c1.mode, new_path1);
1264                 update_file(o, 0, mfi_c2.sha, mfi_c2.mode, new_path2);
1265                 free(new_path2);
1266                 free(new_path1);
1267         }
1268 }
1269
1270 static int process_renames(struct merge_options *o,
1271                            struct string_list *a_renames,
1272                            struct string_list *b_renames)
1273 {
1274         int clean_merge = 1, i, j;
1275         struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
1276         struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
1277         const struct rename *sre;
1278
1279         for (i = 0; i < a_renames->nr; i++) {
1280                 sre = a_renames->items[i].util;
1281                 string_list_insert(&a_by_dst, sre->pair->two->path)->util
1282                         = (void *)sre;
1283         }
1284         for (i = 0; i < b_renames->nr; i++) {
1285                 sre = b_renames->items[i].util;
1286                 string_list_insert(&b_by_dst, sre->pair->two->path)->util
1287                         = (void *)sre;
1288         }
1289
1290         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
1291                 struct string_list *renames1, *renames2Dst;
1292                 struct rename *ren1 = NULL, *ren2 = NULL;
1293                 const char *branch1, *branch2;
1294                 const char *ren1_src, *ren1_dst;
1295                 struct string_list_item *lookup;
1296
1297                 if (i >= a_renames->nr) {
1298                         ren2 = b_renames->items[j++].util;
1299                 } else if (j >= b_renames->nr) {
1300                         ren1 = a_renames->items[i++].util;
1301                 } else {
1302                         int compare = strcmp(a_renames->items[i].string,
1303                                              b_renames->items[j].string);
1304                         if (compare <= 0)
1305                                 ren1 = a_renames->items[i++].util;
1306                         if (compare >= 0)
1307                                 ren2 = b_renames->items[j++].util;
1308                 }
1309
1310                 /* TODO: refactor, so that 1/2 are not needed */
1311                 if (ren1) {
1312                         renames1 = a_renames;
1313                         renames2Dst = &b_by_dst;
1314                         branch1 = o->branch1;
1315                         branch2 = o->branch2;
1316                 } else {
1317                         struct rename *tmp;
1318                         renames1 = b_renames;
1319                         renames2Dst = &a_by_dst;
1320                         branch1 = o->branch2;
1321                         branch2 = o->branch1;
1322                         tmp = ren2;
1323                         ren2 = ren1;
1324                         ren1 = tmp;
1325                 }
1326
1327                 if (ren1->processed)
1328                         continue;
1329                 ren1->processed = 1;
1330                 ren1->dst_entry->processed = 1;
1331                 /* BUG: We should only mark src_entry as processed if we
1332                  * are not dealing with a rename + add-source case.
1333                  */
1334                 ren1->src_entry->processed = 1;
1335
1336                 ren1_src = ren1->pair->one->path;
1337                 ren1_dst = ren1->pair->two->path;
1338
1339                 if (ren2) {
1340                         /* One file renamed on both sides */
1341                         const char *ren2_src = ren2->pair->one->path;
1342                         const char *ren2_dst = ren2->pair->two->path;
1343                         enum rename_type rename_type;
1344                         if (strcmp(ren1_src, ren2_src) != 0)
1345                                 die("ren1_src != ren2_src");
1346                         ren2->dst_entry->processed = 1;
1347                         ren2->processed = 1;
1348                         if (strcmp(ren1_dst, ren2_dst) != 0) {
1349                                 rename_type = RENAME_ONE_FILE_TO_TWO;
1350                                 clean_merge = 0;
1351                         } else {
1352                                 rename_type = RENAME_ONE_FILE_TO_ONE;
1353                                 /* BUG: We should only remove ren1_src in
1354                                  * the base stage (think of rename +
1355                                  * add-source cases).
1356                                  */
1357                                 remove_file(o, 1, ren1_src, 1);
1358                                 update_entry(ren1->dst_entry,
1359                                              ren1->pair->one,
1360                                              ren1->pair->two,
1361                                              ren2->pair->two);
1362                         }
1363                         setup_rename_conflict_info(rename_type,
1364                                                    ren1->pair,
1365                                                    ren2->pair,
1366                                                    branch1,
1367                                                    branch2,
1368                                                    ren1->dst_entry,
1369                                                    ren2->dst_entry,
1370                                                    o,
1371                                                    NULL,
1372                                                    NULL);
1373                 } else if ((lookup = string_list_lookup(renames2Dst, ren1_dst))) {
1374                         /* Two different files renamed to the same thing */
1375                         char *ren2_dst;
1376                         ren2 = lookup->util;
1377                         ren2_dst = ren2->pair->two->path;
1378                         if (strcmp(ren1_dst, ren2_dst) != 0)
1379                                 die("ren1_dst != ren2_dst");
1380
1381                         clean_merge = 0;
1382                         ren2->processed = 1;
1383                         /*
1384                          * BUG: We should only mark src_entry as processed
1385                          * if we are not dealing with a rename + add-source
1386                          * case.
1387                          */
1388                         ren2->src_entry->processed = 1;
1389
1390                         setup_rename_conflict_info(RENAME_TWO_FILES_TO_ONE,
1391                                                    ren1->pair,
1392                                                    ren2->pair,
1393                                                    branch1,
1394                                                    branch2,
1395                                                    ren1->dst_entry,
1396                                                    ren2->dst_entry,
1397                                                    o,
1398                                                    ren1->src_entry,
1399                                                    ren2->src_entry);
1400
1401                 } else {
1402                         /* Renamed in 1, maybe changed in 2 */
1403                         /* we only use sha1 and mode of these */
1404                         struct diff_filespec src_other, dst_other;
1405                         int try_merge;
1406
1407                         /*
1408                          * unpack_trees loads entries from common-commit
1409                          * into stage 1, from head-commit into stage 2, and
1410                          * from merge-commit into stage 3.  We keep track
1411                          * of which side corresponds to the rename.
1412                          */
1413                         int renamed_stage = a_renames == renames1 ? 2 : 3;
1414                         int other_stage =   a_renames == renames1 ? 3 : 2;
1415
1416                         /* BUG: We should only remove ren1_src in the base
1417                          * stage and in other_stage (think of rename +
1418                          * add-source case).
1419                          */
1420                         remove_file(o, 1, ren1_src,
1421                                     renamed_stage == 2 || !was_tracked(ren1_src));
1422
1423                         hashcpy(src_other.sha1, ren1->src_entry->stages[other_stage].sha);
1424                         src_other.mode = ren1->src_entry->stages[other_stage].mode;
1425                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[other_stage].sha);
1426                         dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
1427                         try_merge = 0;
1428
1429                         if (sha_eq(src_other.sha1, null_sha1)) {
1430                                 setup_rename_conflict_info(RENAME_DELETE,
1431                                                            ren1->pair,
1432                                                            NULL,
1433                                                            branch1,
1434                                                            branch2,
1435                                                            ren1->dst_entry,
1436                                                            NULL,
1437                                                            o,
1438                                                            NULL,
1439                                                            NULL);
1440                         } else if ((dst_other.mode == ren1->pair->two->mode) &&
1441                                    sha_eq(dst_other.sha1, ren1->pair->two->sha1)) {
1442                                 /*
1443                                  * Added file on the other side identical to
1444                                  * the file being renamed: clean merge.
1445                                  * Also, there is no need to overwrite the
1446                                  * file already in the working copy, so call
1447                                  * update_file_flags() instead of
1448                                  * update_file().
1449                                  */
1450                                 update_file_flags(o,
1451                                                   ren1->pair->two->sha1,
1452                                                   ren1->pair->two->mode,
1453                                                   ren1_dst,
1454                                                   1, /* update_cache */
1455                                                   0  /* update_wd    */);
1456                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
1457                                 clean_merge = 0;
1458                                 try_merge = 1;
1459                                 output(o, 1, _("CONFLICT (rename/add): Rename %s->%s in %s. "
1460                                        "%s added in %s"),
1461                                        ren1_src, ren1_dst, branch1,
1462                                        ren1_dst, branch2);
1463                                 if (o->call_depth) {
1464                                         struct merge_file_info mfi;
1465                                         mfi = merge_file_one(o, ren1_dst, null_sha1, 0,
1466                                                          ren1->pair->two->sha1, ren1->pair->two->mode,
1467                                                          dst_other.sha1, dst_other.mode,
1468                                                          branch1, branch2);
1469                                         output(o, 1, _("Adding merged %s"), ren1_dst);
1470                                         update_file(o, 0, mfi.sha, mfi.mode, ren1_dst);
1471                                         try_merge = 0;
1472                                 } else {
1473                                         char *new_path = unique_path(o, ren1_dst, branch2);
1474                                         output(o, 1, _("Adding as %s instead"), new_path);
1475                                         update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
1476                                         free(new_path);
1477                                 }
1478                         } else
1479                                 try_merge = 1;
1480
1481                         if (try_merge) {
1482                                 struct diff_filespec *one, *a, *b;
1483                                 src_other.path = (char *)ren1_src;
1484
1485                                 one = ren1->pair->one;
1486                                 if (a_renames == renames1) {
1487                                         a = ren1->pair->two;
1488                                         b = &src_other;
1489                                 } else {
1490                                         b = ren1->pair->two;
1491                                         a = &src_other;
1492                                 }
1493                                 update_entry(ren1->dst_entry, one, a, b);
1494                                 setup_rename_conflict_info(RENAME_NORMAL,
1495                                                            ren1->pair,
1496                                                            NULL,
1497                                                            branch1,
1498                                                            NULL,
1499                                                            ren1->dst_entry,
1500                                                            NULL,
1501                                                            o,
1502                                                            NULL,
1503                                                            NULL);
1504                         }
1505                 }
1506         }
1507         string_list_clear(&a_by_dst, 0);
1508         string_list_clear(&b_by_dst, 0);
1509
1510         return clean_merge;
1511 }
1512
1513 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1514 {
1515         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1516 }
1517
1518 static int read_sha1_strbuf(const unsigned char *sha1, struct strbuf *dst)
1519 {
1520         void *buf;
1521         enum object_type type;
1522         unsigned long size;
1523         buf = read_sha1_file(sha1, &type, &size);
1524         if (!buf)
1525                 return error(_("cannot read object %s"), sha1_to_hex(sha1));
1526         if (type != OBJ_BLOB) {
1527                 free(buf);
1528                 return error(_("object %s is not a blob"), sha1_to_hex(sha1));
1529         }
1530         strbuf_attach(dst, buf, size, size + 1);
1531         return 0;
1532 }
1533
1534 static int blob_unchanged(const unsigned char *o_sha,
1535                           const unsigned char *a_sha,
1536                           int renormalize, const char *path)
1537 {
1538         struct strbuf o = STRBUF_INIT;
1539         struct strbuf a = STRBUF_INIT;
1540         int ret = 0; /* assume changed for safety */
1541
1542         if (sha_eq(o_sha, a_sha))
1543                 return 1;
1544         if (!renormalize)
1545                 return 0;
1546
1547         assert(o_sha && a_sha);
1548         if (read_sha1_strbuf(o_sha, &o) || read_sha1_strbuf(a_sha, &a))
1549                 goto error_return;
1550         /*
1551          * Note: binary | is used so that both renormalizations are
1552          * performed.  Comparison can be skipped if both files are
1553          * unchanged since their sha1s have already been compared.
1554          */
1555         if (renormalize_buffer(path, o.buf, o.len, &o) |
1556             renormalize_buffer(path, a.buf, a.len, &a))
1557                 ret = (o.len == a.len && !memcmp(o.buf, a.buf, o.len));
1558
1559 error_return:
1560         strbuf_release(&o);
1561         strbuf_release(&a);
1562         return ret;
1563 }
1564
1565 static void handle_modify_delete(struct merge_options *o,
1566                                  const char *path,
1567                                  unsigned char *o_sha, int o_mode,
1568                                  unsigned char *a_sha, int a_mode,
1569                                  unsigned char *b_sha, int b_mode)
1570 {
1571         handle_change_delete(o,
1572                              path,
1573                              o_sha, o_mode,
1574                              a_sha, a_mode,
1575                              b_sha, b_mode,
1576                              _("modify"), _("modified"));
1577 }
1578
1579 static int merge_content(struct merge_options *o,
1580                          const char *path,
1581                          unsigned char *o_sha, int o_mode,
1582                          unsigned char *a_sha, int a_mode,
1583                          unsigned char *b_sha, int b_mode,
1584                          struct rename_conflict_info *rename_conflict_info)
1585 {
1586         const char *reason = _("content");
1587         const char *path1 = NULL, *path2 = NULL;
1588         struct merge_file_info mfi;
1589         struct diff_filespec one, a, b;
1590         unsigned df_conflict_remains = 0;
1591
1592         if (!o_sha) {
1593                 reason = _("add/add");
1594                 o_sha = (unsigned char *)null_sha1;
1595         }
1596         one.path = a.path = b.path = (char *)path;
1597         hashcpy(one.sha1, o_sha);
1598         one.mode = o_mode;
1599         hashcpy(a.sha1, a_sha);
1600         a.mode = a_mode;
1601         hashcpy(b.sha1, b_sha);
1602         b.mode = b_mode;
1603
1604         if (rename_conflict_info) {
1605                 struct diff_filepair *pair1 = rename_conflict_info->pair1;
1606
1607                 path1 = (o->branch1 == rename_conflict_info->branch1) ?
1608                         pair1->two->path : pair1->one->path;
1609                 /* If rename_conflict_info->pair2 != NULL, we are in
1610                  * RENAME_ONE_FILE_TO_ONE case.  Otherwise, we have a
1611                  * normal rename.
1612                  */
1613                 path2 = (rename_conflict_info->pair2 ||
1614                          o->branch2 == rename_conflict_info->branch1) ?
1615                         pair1->two->path : pair1->one->path;
1616
1617                 if (dir_in_way(path, !o->call_depth))
1618                         df_conflict_remains = 1;
1619         }
1620         mfi = merge_file_special_markers(o, &one, &a, &b,
1621                                          o->branch1, path1,
1622                                          o->branch2, path2);
1623
1624         if (mfi.clean && !df_conflict_remains &&
1625             sha_eq(mfi.sha, a_sha) && mfi.mode == a_mode) {
1626                 int path_renamed_outside_HEAD;
1627                 output(o, 3, _("Skipped %s (merged same as existing)"), path);
1628                 /*
1629                  * The content merge resulted in the same file contents we
1630                  * already had.  We can return early if those file contents
1631                  * are recorded at the correct path (which may not be true
1632                  * if the merge involves a rename).
1633                  */
1634                 path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
1635                 if (!path_renamed_outside_HEAD) {
1636                         add_cacheinfo(mfi.mode, mfi.sha, path,
1637                                       0, (!o->call_depth), 0);
1638                         return mfi.clean;
1639                 }
1640         } else
1641                 output(o, 2, _("Auto-merging %s"), path);
1642
1643         if (!mfi.clean) {
1644                 if (S_ISGITLINK(mfi.mode))
1645                         reason = _("submodule");
1646                 output(o, 1, _("CONFLICT (%s): Merge conflict in %s"),
1647                                 reason, path);
1648                 if (rename_conflict_info && !df_conflict_remains)
1649                         update_stages(path, &one, &a, &b);
1650         }
1651
1652         if (df_conflict_remains) {
1653                 char *new_path;
1654                 if (o->call_depth) {
1655                         remove_file_from_cache(path);
1656                 } else {
1657                         if (!mfi.clean)
1658                                 update_stages(path, &one, &a, &b);
1659                         else {
1660                                 int file_from_stage2 = was_tracked(path);
1661                                 struct diff_filespec merged;
1662                                 hashcpy(merged.sha1, mfi.sha);
1663                                 merged.mode = mfi.mode;
1664
1665                                 update_stages(path, NULL,
1666                                               file_from_stage2 ? &merged : NULL,
1667                                               file_from_stage2 ? NULL : &merged);
1668                         }
1669
1670                 }
1671                 new_path = unique_path(o, path, rename_conflict_info->branch1);
1672                 output(o, 1, _("Adding as %s instead"), new_path);
1673                 update_file(o, 0, mfi.sha, mfi.mode, new_path);
1674                 free(new_path);
1675                 mfi.clean = 0;
1676         } else {
1677                 update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
1678         }
1679         return mfi.clean;
1680
1681 }
1682
1683 /* Per entry merge function */
1684 static int process_entry(struct merge_options *o,
1685                          const char *path, struct stage_data *entry)
1686 {
1687         int clean_merge = 1;
1688         int normalize = o->renormalize;
1689         unsigned o_mode = entry->stages[1].mode;
1690         unsigned a_mode = entry->stages[2].mode;
1691         unsigned b_mode = entry->stages[3].mode;
1692         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1693         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1694         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1695
1696         entry->processed = 1;
1697         if (entry->rename_conflict_info) {
1698                 struct rename_conflict_info *conflict_info = entry->rename_conflict_info;
1699                 switch (conflict_info->rename_type) {
1700                 case RENAME_NORMAL:
1701                 case RENAME_ONE_FILE_TO_ONE:
1702                         clean_merge = merge_content(o, path,
1703                                                     o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
1704                                                     conflict_info);
1705                         break;
1706                 case RENAME_DELETE:
1707                         clean_merge = 0;
1708                         conflict_rename_delete(o, conflict_info->pair1,
1709                                                conflict_info->branch1,
1710                                                conflict_info->branch2);
1711                         break;
1712                 case RENAME_ONE_FILE_TO_TWO:
1713                         clean_merge = 0;
1714                         conflict_rename_rename_1to2(o, conflict_info);
1715                         break;
1716                 case RENAME_TWO_FILES_TO_ONE:
1717                         clean_merge = 0;
1718                         conflict_rename_rename_2to1(o, conflict_info);
1719                         break;
1720                 default:
1721                         entry->processed = 0;
1722                         break;
1723                 }
1724         } else if (o_sha && (!a_sha || !b_sha)) {
1725                 /* Case A: Deleted in one */
1726                 if ((!a_sha && !b_sha) ||
1727                     (!b_sha && blob_unchanged(o_sha, a_sha, normalize, path)) ||
1728                     (!a_sha && blob_unchanged(o_sha, b_sha, normalize, path))) {
1729                         /* Deleted in both or deleted in one and
1730                          * unchanged in the other */
1731                         if (a_sha)
1732                                 output(o, 2, _("Removing %s"), path);
1733                         /* do not touch working file if it did not exist */
1734                         remove_file(o, 1, path, !a_sha);
1735                 } else {
1736                         /* Modify/delete; deleted side may have put a directory in the way */
1737                         clean_merge = 0;
1738                         handle_modify_delete(o, path, o_sha, o_mode,
1739                                              a_sha, a_mode, b_sha, b_mode);
1740                 }
1741         } else if ((!o_sha && a_sha && !b_sha) ||
1742                    (!o_sha && !a_sha && b_sha)) {
1743                 /* Case B: Added in one. */
1744                 /* [nothing|directory] -> ([nothing|directory], file) */
1745
1746                 const char *add_branch;
1747                 const char *other_branch;
1748                 unsigned mode;
1749                 const unsigned char *sha;
1750                 const char *conf;
1751
1752                 if (a_sha) {
1753                         add_branch = o->branch1;
1754                         other_branch = o->branch2;
1755                         mode = a_mode;
1756                         sha = a_sha;
1757                         conf = _("file/directory");
1758                 } else {
1759                         add_branch = o->branch2;
1760                         other_branch = o->branch1;
1761                         mode = b_mode;
1762                         sha = b_sha;
1763                         conf = _("directory/file");
1764                 }
1765                 if (dir_in_way(path, !o->call_depth)) {
1766                         char *new_path = unique_path(o, path, add_branch);
1767                         clean_merge = 0;
1768                         output(o, 1, _("CONFLICT (%s): There is a directory with name %s in %s. "
1769                                "Adding %s as %s"),
1770                                conf, path, other_branch, path, new_path);
1771                         if (o->call_depth)
1772                                 remove_file_from_cache(path);
1773                         update_file(o, 0, sha, mode, new_path);
1774                         if (o->call_depth)
1775                                 remove_file_from_cache(path);
1776                         free(new_path);
1777                 } else {
1778                         output(o, 2, _("Adding %s"), path);
1779                         /* do not overwrite file if already present */
1780                         update_file_flags(o, sha, mode, path, 1, !a_sha);
1781                 }
1782         } else if (a_sha && b_sha) {
1783                 /* Case C: Added in both (check for same permissions) and */
1784                 /* case D: Modified in both, but differently. */
1785                 clean_merge = merge_content(o, path,
1786                                             o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
1787                                             NULL);
1788         } else if (!o_sha && !a_sha && !b_sha) {
1789                 /*
1790                  * this entry was deleted altogether. a_mode == 0 means
1791                  * we had that path and want to actively remove it.
1792                  */
1793                 remove_file(o, 1, path, !a_mode);
1794         } else
1795                 die(_("Fatal merge failure, shouldn't happen."));
1796
1797         return clean_merge;
1798 }
1799
1800 int merge_trees(struct merge_options *o,
1801                 struct tree *head,
1802                 struct tree *merge,
1803                 struct tree *common,
1804                 struct tree **result)
1805 {
1806         int code, clean;
1807
1808         if (o->subtree_shift) {
1809                 merge = shift_tree_object(head, merge, o->subtree_shift);
1810                 common = shift_tree_object(head, common, o->subtree_shift);
1811         }
1812
1813         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1814                 output(o, 0, _("Already up-to-date!"));
1815                 *result = head;
1816                 return 1;
1817         }
1818
1819         code = git_merge_trees(o->call_depth, common, head, merge);
1820
1821         if (code != 0) {
1822                 if (show(o, 4) || o->call_depth)
1823                         die(_("merging of trees %s and %s failed"),
1824                             sha1_to_hex(head->object.sha1),
1825                             sha1_to_hex(merge->object.sha1));
1826                 else
1827                         exit(128);
1828         }
1829
1830         if (unmerged_cache()) {
1831                 struct string_list *entries, *re_head, *re_merge;
1832                 int i;
1833                 string_list_clear(&o->current_file_set, 1);
1834                 string_list_clear(&o->current_directory_set, 1);
1835                 get_files_dirs(o, head);
1836                 get_files_dirs(o, merge);
1837
1838                 entries = get_unmerged();
1839                 record_df_conflict_files(o, entries);
1840                 re_head  = get_renames(o, head, common, head, merge, entries);
1841                 re_merge = get_renames(o, merge, common, head, merge, entries);
1842                 clean = process_renames(o, re_head, re_merge);
1843                 for (i = entries->nr-1; 0 <= i; i--) {
1844                         const char *path = entries->items[i].string;
1845                         struct stage_data *e = entries->items[i].util;
1846                         if (!e->processed
1847                                 && !process_entry(o, path, e))
1848                                 clean = 0;
1849                 }
1850                 for (i = 0; i < entries->nr; i++) {
1851                         struct stage_data *e = entries->items[i].util;
1852                         if (!e->processed)
1853                                 die(_("Unprocessed path??? %s"),
1854                                     entries->items[i].string);
1855                 }
1856
1857                 string_list_clear(re_merge, 0);
1858                 string_list_clear(re_head, 0);
1859                 string_list_clear(entries, 1);
1860
1861                 free(re_merge);
1862                 free(re_head);
1863                 free(entries);
1864         }
1865         else
1866                 clean = 1;
1867
1868         if (o->call_depth)
1869                 *result = write_tree_from_memory(o);
1870
1871         return clean;
1872 }
1873
1874 static struct commit_list *reverse_commit_list(struct commit_list *list)
1875 {
1876         struct commit_list *next = NULL, *current, *backup;
1877         for (current = list; current; current = backup) {
1878                 backup = current->next;
1879                 current->next = next;
1880                 next = current;
1881         }
1882         return next;
1883 }
1884
1885 /*
1886  * Merge the commits h1 and h2, return the resulting virtual
1887  * commit object and a flag indicating the cleanness of the merge.
1888  */
1889 int merge_recursive(struct merge_options *o,
1890                     struct commit *h1,
1891                     struct commit *h2,
1892                     struct commit_list *ca,
1893                     struct commit **result)
1894 {
1895         struct commit_list *iter;
1896         struct commit *merged_common_ancestors;
1897         struct tree *mrtree = mrtree;
1898         int clean;
1899
1900         if (show(o, 4)) {
1901                 output(o, 4, _("Merging:"));
1902                 output_commit_title(o, h1);
1903                 output_commit_title(o, h2);
1904         }
1905
1906         if (!ca) {
1907                 ca = get_merge_bases(h1, h2);
1908                 ca = reverse_commit_list(ca);
1909         }
1910
1911         if (show(o, 5)) {
1912                 unsigned cnt = commit_list_count(ca);
1913
1914                 output(o, 5, Q_("found %u common ancestor:",
1915                                 "found %u common ancestors:", cnt), cnt);
1916                 for (iter = ca; iter; iter = iter->next)
1917                         output_commit_title(o, iter->item);
1918         }
1919
1920         merged_common_ancestors = pop_commit(&ca);
1921         if (merged_common_ancestors == NULL) {
1922                 /* if there is no common ancestor, use an empty tree */
1923                 struct tree *tree;
1924
1925                 tree = lookup_tree(EMPTY_TREE_SHA1_BIN);
1926                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1927         }
1928
1929         for (iter = ca; iter; iter = iter->next) {
1930                 const char *saved_b1, *saved_b2;
1931                 o->call_depth++;
1932                 /*
1933                  * When the merge fails, the result contains files
1934                  * with conflict markers. The cleanness flag is
1935                  * ignored, it was never actually used, as result of
1936                  * merge_trees has always overwritten it: the committed
1937                  * "conflicts" were already resolved.
1938                  */
1939                 discard_cache();
1940                 saved_b1 = o->branch1;
1941                 saved_b2 = o->branch2;
1942                 o->branch1 = "Temporary merge branch 1";
1943                 o->branch2 = "Temporary merge branch 2";
1944                 merge_recursive(o, merged_common_ancestors, iter->item,
1945                                 NULL, &merged_common_ancestors);
1946                 o->branch1 = saved_b1;
1947                 o->branch2 = saved_b2;
1948                 o->call_depth--;
1949
1950                 if (!merged_common_ancestors)
1951                         die(_("merge returned no commit"));
1952         }
1953
1954         discard_cache();
1955         if (!o->call_depth)
1956                 read_cache();
1957
1958         o->ancestor = "merged common ancestors";
1959         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
1960                             &mrtree);
1961
1962         if (o->call_depth) {
1963                 *result = make_virtual_commit(mrtree, "merged tree");
1964                 commit_list_insert(h1, &(*result)->parents);
1965                 commit_list_insert(h2, &(*result)->parents->next);
1966         }
1967         flush_output(o);
1968         if (show(o, 2))
1969                 diff_warn_rename_limit("merge.renamelimit",
1970                                        o->needed_rename_limit, 0);
1971         return clean;
1972 }
1973
1974 static struct commit *get_ref(const unsigned char *sha1, const char *name)
1975 {
1976         struct object *object;
1977
1978         object = deref_tag(parse_object(sha1), name, strlen(name));
1979         if (!object)
1980                 return NULL;
1981         if (object->type == OBJ_TREE)
1982                 return make_virtual_commit((struct tree*)object, name);
1983         if (object->type != OBJ_COMMIT)
1984                 return NULL;
1985         if (parse_commit((struct commit *)object))
1986                 return NULL;
1987         return (struct commit *)object;
1988 }
1989
1990 int merge_recursive_generic(struct merge_options *o,
1991                             const unsigned char *head,
1992                             const unsigned char *merge,
1993                             int num_base_list,
1994                             const unsigned char **base_list,
1995                             struct commit **result)
1996 {
1997         int clean;
1998         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1999         struct commit *head_commit = get_ref(head, o->branch1);
2000         struct commit *next_commit = get_ref(merge, o->branch2);
2001         struct commit_list *ca = NULL;
2002
2003         if (base_list) {
2004                 int i;
2005                 for (i = 0; i < num_base_list; ++i) {
2006                         struct commit *base;
2007                         if (!(base = get_ref(base_list[i], sha1_to_hex(base_list[i]))))
2008                                 return error(_("Could not parse object '%s'"),
2009                                         sha1_to_hex(base_list[i]));
2010                         commit_list_insert(base, &ca);
2011                 }
2012         }
2013
2014         hold_locked_index(lock, 1);
2015         clean = merge_recursive(o, head_commit, next_commit, ca,
2016                         result);
2017         if (active_cache_changed &&
2018             write_locked_index(&the_index, lock, COMMIT_LOCK))
2019                 return error(_("Unable to write index."));
2020
2021         return clean ? 0 : 1;
2022 }
2023
2024 static void merge_recursive_config(struct merge_options *o)
2025 {
2026         git_config_get_int("merge.verbosity", &o->verbosity);
2027         git_config_get_int("diff.renamelimit", &o->diff_rename_limit);
2028         git_config_get_int("merge.renamelimit", &o->merge_rename_limit);
2029         git_config(git_xmerge_config, NULL);
2030 }
2031
2032 void init_merge_options(struct merge_options *o)
2033 {
2034         memset(o, 0, sizeof(struct merge_options));
2035         o->verbosity = 2;
2036         o->buffer_output = 1;
2037         o->diff_rename_limit = -1;
2038         o->merge_rename_limit = -1;
2039         o->renormalize = 0;
2040         merge_recursive_config(o);
2041         if (getenv("GIT_MERGE_VERBOSITY"))
2042                 o->verbosity =
2043                         strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
2044         if (o->verbosity >= 5)
2045                 o->buffer_output = 0;
2046         strbuf_init(&o->obuf, 0);
2047         string_list_init(&o->current_file_set, 1);
2048         string_list_init(&o->current_directory_set, 1);
2049         string_list_init(&o->df_conflict_file_set, 1);
2050 }
2051
2052 int parse_merge_opt(struct merge_options *o, const char *s)
2053 {
2054         const char *arg;
2055
2056         if (!s || !*s)
2057                 return -1;
2058         if (!strcmp(s, "ours"))
2059                 o->recursive_variant = MERGE_RECURSIVE_OURS;
2060         else if (!strcmp(s, "theirs"))
2061                 o->recursive_variant = MERGE_RECURSIVE_THEIRS;
2062         else if (!strcmp(s, "subtree"))
2063                 o->subtree_shift = "";
2064         else if (skip_prefix(s, "subtree=", &arg))
2065                 o->subtree_shift = arg;
2066         else if (!strcmp(s, "patience"))
2067                 o->xdl_opts = DIFF_WITH_ALG(o, PATIENCE_DIFF);
2068         else if (!strcmp(s, "histogram"))
2069                 o->xdl_opts = DIFF_WITH_ALG(o, HISTOGRAM_DIFF);
2070         else if (skip_prefix(s, "diff-algorithm=", &arg)) {
2071                 long value = parse_algorithm_value(arg);
2072                 if (value < 0)
2073                         return -1;
2074                 /* clear out previous settings */
2075                 DIFF_XDL_CLR(o, NEED_MINIMAL);
2076                 o->xdl_opts &= ~XDF_DIFF_ALGORITHM_MASK;
2077                 o->xdl_opts |= value;
2078         }
2079         else if (!strcmp(s, "ignore-space-change"))
2080                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_CHANGE;
2081         else if (!strcmp(s, "ignore-all-space"))
2082                 o->xdl_opts |= XDF_IGNORE_WHITESPACE;
2083         else if (!strcmp(s, "ignore-space-at-eol"))
2084                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_AT_EOL;
2085         else if (!strcmp(s, "renormalize"))
2086                 o->renormalize = 1;
2087         else if (!strcmp(s, "no-renormalize"))
2088                 o->renormalize = 0;
2089         else if (skip_prefix(s, "rename-threshold=", &arg)) {
2090                 if ((o->rename_score = parse_rename_score(&arg)) == -1 || *arg != 0)
2091                         return -1;
2092         }
2093         else
2094                 return -1;
2095         return 0;
2096 }