merge-recursive.c

   1 /*
   2  * Recursive Merge algorithm stolen from git-merge-recursive.py by
   3  * Fredrik Kuivinen.
   4  * The thieves were Alex Riesen and Johannes Schindelin, in June/July 2006
   5  */
   6 #include "advice.h"
   7 #include "cache.h"
   8 #include "cache-tree.h"
   9 #include "commit.h"
  10 #include "blob.h"
  11 #include "builtin.h"
  12 #include "tree-walk.h"
  13 #include "diff.h"
  14 #include "diffcore.h"
  15 #include "tag.h"
  16 #include "unpack-trees.h"
  17 #include "string-list.h"
  18 #include "xdiff-interface.h"
  19 #include "ll-merge.h"
  20 #include "attr.h"
  21 #include "merge-recursive.h"
  22 #include "dir.h"
  23
  24 static struct tree *shift_tree_object(struct tree *one, struct tree *two)
  25 {
  26         unsigned char shifted[20];
  27
  28         /*
  29          * NEEDSWORK: this limits the recursion depth to hardcoded
  30          * value '2' to avoid excessive overhead.
  31          */
  32         shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
  33         if (!hashcmp(two->object.sha1, shifted))
  34                 return two;
  35         return lookup_tree(shifted);
  36 }
  37
  38 /*
  39  * A virtual commit has (const char *)commit->util set to the name.
  40  */
  41
  42 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  43 {
  44         struct commit *commit = xcalloc(1, sizeof(struct commit));
  45         commit->tree = tree;
  46         commit->util = (void*)comment;
  47         /* avoid warnings */
  48         commit->object.parsed = 1;
  49         return commit;
  50 }
  51
  52 /*
  53  * Since we use get_tree_entry(), which does not put the read object into
  54  * the object pool, we cannot rely on a == b.
  55  */
  56 static int sha_eq(const unsigned char *a, const unsigned char *b)
  57 {
  58         if (!a && !b)
  59                 return 2;
  60         return a && b && hashcmp(a, b) == 0;
  61 }
  62
  63 /*
  64  * Since we want to write the index eventually, we cannot reuse the index
  65  * for these (temporary) data.
  66  */
  67 struct stage_data
  68 {
  69         struct
  70         {
  71                 unsigned mode;
  72                 unsigned char sha[20];
  73         } stages[4];
  74         unsigned processed:1;
  75 };
  76
  77 static int show(struct merge_options *o, int v)
  78 {
  79         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
  80 }
  81
  82 static void flush_output(struct merge_options *o)
  83 {
  84         if (o->obuf.len) {
  85                 fputs(o->obuf.buf, stdout);
  86                 strbuf_reset(&o->obuf);
  87         }
  88 }
  89
  90 static void output(struct merge_options *o, int v, const char *fmt, ...)
  91 {
  92         int len;
  93         va_list ap;
  94
  95         if (!show(o, v))
  96                 return;
  97
  98         strbuf_grow(&o->obuf, o->call_depth * 2 + 2);
  99         memset(o->obuf.buf + o->obuf.len, ' ', o->call_depth * 2);
 100         strbuf_setlen(&o->obuf, o->obuf.len + o->call_depth * 2);
 101
 102         va_start(ap, fmt);
 103         len = vsnprintf(o->obuf.buf + o->obuf.len, strbuf_avail(&o->obuf), fmt, ap);
 104         va_end(ap);
 105
 106         if (len < 0)
 107                 len = 0;
 108         if (len >= strbuf_avail(&o->obuf)) {
 109                 strbuf_grow(&o->obuf, len + 2);
 110                 va_start(ap, fmt);
 111                 len = vsnprintf(o->obuf.buf + o->obuf.len, strbuf_avail(&o->obuf), fmt, ap);
 112                 va_end(ap);
 113                 if (len >= strbuf_avail(&o->obuf)) {
 114                         die("this should not happen, your snprintf is broken");
 115                 }
 116         }
 117         strbuf_setlen(&o->obuf, o->obuf.len + len);
 118         strbuf_add(&o->obuf, "\n", 1);
 119         if (!o->buffer_output)
 120                 flush_output(o);
 121 }
 122
 123 static void output_commit_title(struct merge_options *o, struct commit *commit)
 124 {
 125         int i;
 126         flush_output(o);
 127         for (i = o->call_depth; i--;)
 128                 fputs("  ", stdout);
 129         if (commit->util)
 130                 printf("virtual %s\n", (char *)commit->util);
 131         else {
 132                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 133                 if (parse_commit(commit) != 0)
 134                         printf("(bad commit)\n");
 135                 else {
 136                         const char *s;
 137                         int len;
 138                         for (s = commit->buffer; *s; s++)
 139                                 if (*s == '\n' && s[1] == '\n') {
 140                                         s += 2;
 141                                         break;
 142                                 }
 143                         for (len = 0; s[len] && '\n' != s[len]; len++)
 144                                 ; /* do nothing */
 145                         printf("%.*s\n", len, s);
 146                 }
 147         }
 148 }
 149
 150 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 151                 const char *path, int stage, int refresh, int options)
 152 {
 153         struct cache_entry *ce;
 154         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 155         if (!ce)
 156                 return error("addinfo_cache failed for path '%s'", path);
 157         return add_cache_entry(ce, options);
 158 }
 159
 160 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 161 {
 162         parse_tree(tree);
 163         init_tree_desc(desc, tree->buffer, tree->size);
 164 }
 165
 166 static int git_merge_trees(int index_only,
 167                            struct tree *common,
 168                            struct tree *head,
 169                            struct tree *merge)
 170 {
 171         int rc;
 172         struct tree_desc t[3];
 173         struct unpack_trees_options opts;
 174
 175         memset(&opts, 0, sizeof(opts));
 176         if (index_only)
 177                 opts.index_only = 1;
 178         else
 179                 opts.update = 1;
 180         opts.merge = 1;
 181         opts.head_idx = 2;
 182         opts.fn = threeway_merge;
 183         opts.src_index = &the_index;
 184         opts.dst_index = &the_index;
 185         opts.msgs = get_porcelain_error_msgs();
 186
 187         init_tree_desc_from_tree(t+0, common);
 188         init_tree_desc_from_tree(t+1, head);
 189         init_tree_desc_from_tree(t+2, merge);
 190
 191         rc = unpack_trees(3, t, &opts);
 192         cache_tree_free(&active_cache_tree);
 193         return rc;
 194 }
 195
 196 struct tree *write_tree_from_memory(struct merge_options *o)
 197 {
 198         struct tree *result = NULL;
 199
 200         if (unmerged_cache()) {
 201                 int i;
 202                 output(o, 0, "There are unmerged index entries:");
 203                 for (i = 0; i < active_nr; i++) {
 204                         struct cache_entry *ce = active_cache[i];
 205                         if (ce_stage(ce))
 206                                 output(o, 0, "%d %.*s", ce_stage(ce), ce_namelen(ce), ce->name);
 207                 }
 208                 return NULL;
 209         }
 210
 211         if (!active_cache_tree)
 212                 active_cache_tree = cache_tree();
 213
 214         if (!cache_tree_fully_valid(active_cache_tree) &&
 215             cache_tree_update(active_cache_tree,
 216                               active_cache, active_nr, 0, 0) < 0)
 217                 die("error building trees");
 218
 219         result = lookup_tree(active_cache_tree->sha1);
 220
 221         return result;
 222 }
 223
 224 static int save_files_dirs(const unsigned char *sha1,
 225                 const char *base, int baselen, const char *path,
 226                 unsigned int mode, int stage, void *context)
 227 {
 228         int len = strlen(path);
 229         char *newpath = xmalloc(baselen + len + 1);
 230         struct merge_options *o = context;
 231
 232         memcpy(newpath, base, baselen);
 233         memcpy(newpath + baselen, path, len);
 234         newpath[baselen + len] = '\0';
 235
 236         if (S_ISDIR(mode))
 237                 string_list_insert(newpath, &o->current_directory_set);
 238         else
 239                 string_list_insert(newpath, &o->current_file_set);
 240         free(newpath);
 241
 242         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
 243 }
 244
 245 static int get_files_dirs(struct merge_options *o, struct tree *tree)
 246 {
 247         int n;
 248         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs, o))
 249                 return 0;
 250         n = o->current_file_set.nr + o->current_directory_set.nr;
 251         return n;
 252 }
 253
 254 /*
 255  * Returns an index_entry instance which doesn't have to correspond to
 256  * a real cache entry in Git's index.
 257  */
 258 static struct stage_data *insert_stage_data(const char *path,
 259                 struct tree *o, struct tree *a, struct tree *b,
 260                 struct string_list *entries)
 261 {
 262         struct string_list_item *item;
 263         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 264         get_tree_entry(o->object.sha1, path,
 265                         e->stages[1].sha, &e->stages[1].mode);
 266         get_tree_entry(a->object.sha1, path,
 267                         e->stages[2].sha, &e->stages[2].mode);
 268         get_tree_entry(b->object.sha1, path,
 269                         e->stages[3].sha, &e->stages[3].mode);
 270         item = string_list_insert(path, entries);
 271         item->util = e;
 272         return e;
 273 }
 274
 275 /*
 276  * Create a dictionary mapping file names to stage_data objects. The
 277  * dictionary contains one entry for every path with a non-zero stage entry.
 278  */
 279 static struct string_list *get_unmerged(void)
 280 {
 281         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
 282         int i;
 283
 284         unmerged->strdup_strings = 1;
 285
 286         for (i = 0; i < active_nr; i++) {
 287                 struct string_list_item *item;
 288                 struct stage_data *e;
 289                 struct cache_entry *ce = active_cache[i];
 290                 if (!ce_stage(ce))
 291                         continue;
 292
 293                 item = string_list_lookup(ce->name, unmerged);
 294                 if (!item) {
 295                         item = string_list_insert(ce->name, unmerged);
 296                         item->util = xcalloc(1, sizeof(struct stage_data));
 297                 }
 298                 e = item->util;
 299                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
 300                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 301         }
 302
 303         return unmerged;
 304 }
 305
 306 struct rename
 307 {
 308         struct diff_filepair *pair;
 309         struct stage_data *src_entry;
 310         struct stage_data *dst_entry;
 311         unsigned processed:1;
 312 };
 313
 314 /*
 315  * Get information of all renames which occurred between 'o_tree' and
 316  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 317  * 'b_tree') to be able to associate the correct cache entries with
 318  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 319  */
 320 static struct string_list *get_renames(struct merge_options *o,
 321                                        struct tree *tree,
 322                                        struct tree *o_tree,
 323                                        struct tree *a_tree,
 324                                        struct tree *b_tree,
 325                                        struct string_list *entries)
 326 {
 327         int i;
 328         struct string_list *renames;
 329         struct diff_options opts;
 330
 331         renames = xcalloc(1, sizeof(struct string_list));
 332         diff_setup(&opts);
 333         DIFF_OPT_SET(&opts, RECURSIVE);
 334         opts.detect_rename = DIFF_DETECT_RENAME;
 335         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 336                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 337                             500;
 338         opts.warn_on_too_large_rename = 1;
 339         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 340         if (diff_setup_done(&opts) < 0)
 341                 die("diff setup failed");
 342         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 343         diffcore_std(&opts);
 344         for (i = 0; i < diff_queued_diff.nr; ++i) {
 345                 struct string_list_item *item;
 346                 struct rename *re;
 347                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 348                 if (pair->status != 'R') {
 349                         diff_free_filepair(pair);
 350                         continue;
 351                 }
 352                 re = xmalloc(sizeof(*re));
 353                 re->processed = 0;
 354                 re->pair = pair;
 355                 item = string_list_lookup(re->pair->one->path, entries);
 356                 if (!item)
 357                         re->src_entry = insert_stage_data(re->pair->one->path,
 358                                         o_tree, a_tree, b_tree, entries);
 359                 else
 360                         re->src_entry = item->util;
 361
 362                 item = string_list_lookup(re->pair->two->path, entries);
 363                 if (!item)
 364                         re->dst_entry = insert_stage_data(re->pair->two->path,
 365                                         o_tree, a_tree, b_tree, entries);
 366                 else
 367                         re->dst_entry = item->util;
 368                 item = string_list_insert(pair->one->path, renames);
 369                 item->util = re;
 370         }
 371         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 372         diff_queued_diff.nr = 0;
 373         diff_flush(&opts);
 374         return renames;
 375 }
 376
 377 static int update_stages(const char *path, struct diff_filespec *o,
 378                          struct diff_filespec *a, struct diff_filespec *b,
 379                          int clear)
 380 {
 381         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 382         if (clear)
 383                 if (remove_file_from_cache(path))
 384                         return -1;
 385         if (o)
 386                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 387                         return -1;
 388         if (a)
 389                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 390                         return -1;
 391         if (b)
 392                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 393                         return -1;
 394         return 0;
 395 }
 396
 397 static int remove_file(struct merge_options *o, int clean,
 398                        const char *path, int no_wd)
 399 {
 400         int update_cache = o->call_depth || clean;
 401         int update_working_directory = !o->call_depth && !no_wd;
 402
 403         if (update_cache) {
 404                 if (remove_file_from_cache(path))
 405                         return -1;
 406         }
 407         if (update_working_directory) {
 408                 if (remove_path(path) && errno != ENOENT)
 409                         return -1;
 410         }
 411         return 0;
 412 }
 413
 414 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
 415 {
 416         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 417         int suffix = 0;
 418         struct stat st;
 419         char *p = newpath + strlen(path);
 420         strcpy(newpath, path);
 421         *(p++) = '~';
 422         strcpy(p, branch);
 423         for (; *p; ++p)
 424                 if ('/' == *p)
 425                         *p = '_';
 426         while (string_list_has_string(&o->current_file_set, newpath) ||
 427                string_list_has_string(&o->current_directory_set, newpath) ||
 428                lstat(newpath, &st) == 0)
 429                 sprintf(p, "_%d", suffix++);
 430
 431         string_list_insert(newpath, &o->current_file_set);
 432         return newpath;
 433 }
 434
 435 static void flush_buffer(int fd, const char *buf, unsigned long size)
 436 {
 437         while (size > 0) {
 438                 long ret = write_in_full(fd, buf, size);
 439                 if (ret < 0) {
 440                         /* Ignore epipe */
 441                         if (errno == EPIPE)
 442                                 break;
 443                         die_errno("merge-recursive");
 444                 } else if (!ret) {
 445                         die("merge-recursive: disk full?");
 446                 }
 447                 size -= ret;
 448                 buf += ret;
 449         }
 450 }
 451
 452 static int would_lose_untracked(const char *path)
 453 {
 454         int pos = cache_name_pos(path, strlen(path));
 455
 456         if (pos < 0)
 457                 pos = -1 - pos;
 458         while (pos < active_nr &&
 459                !strcmp(path, active_cache[pos]->name)) {
 460                 /*
 461                  * If stage #0, it is definitely tracked.
 462                  * If it has stage #2 then it was tracked
 463                  * before this merge started.  All other
 464                  * cases the path was not tracked.
 465                  */
 466                 switch (ce_stage(active_cache[pos])) {
 467                 case 0:
 468                 case 2:
 469                         return 0;
 470                 }
 471                 pos++;
 472         }
 473         return file_exists(path);
 474 }
 475
 476 static int make_room_for_path(const char *path)
 477 {
 478         int status;
 479         const char *msg = "failed to create path '%s'%s";
 480
 481         status = safe_create_leading_directories_const(path);
 482         if (status) {
 483                 if (status == -3) {
 484                         /* something else exists */
 485                         error(msg, path, ": perhaps a D/F conflict?");
 486                         return -1;
 487                 }
 488                 die(msg, path, "");
 489         }
 490
 491         /*
 492          * Do not unlink a file in the work tree if we are not
 493          * tracking it.
 494          */
 495         if (would_lose_untracked(path))
 496                 return error("refusing to lose untracked file at '%s'",
 497                              path);
 498
 499         /* Successful unlink is good.. */
 500         if (!unlink(path))
 501                 return 0;
 502         /* .. and so is no existing file */
 503         if (errno == ENOENT)
 504                 return 0;
 505         /* .. but not some other error (who really cares what?) */
 506         return error(msg, path, ": perhaps a D/F conflict?");
 507 }
 508
 509 static void update_file_flags(struct merge_options *o,
 510                               const unsigned char *sha,
 511                               unsigned mode,
 512                               const char *path,
 513                               int update_cache,
 514                               int update_wd)
 515 {
 516         if (o->call_depth)
 517                 update_wd = 0;
 518
 519         if (update_wd) {
 520                 enum object_type type;
 521                 void *buf;
 522                 unsigned long size;
 523
 524                 if (S_ISGITLINK(mode))
 525                         /*
 526                          * We may later decide to recursively descend into
 527                          * the submodule directory and update its index
 528                          * and/or work tree, but we do not do that now.
 529                          */
 530                         goto update_index;
 531
 532                 buf = read_sha1_file(sha, &type, &size);
 533                 if (!buf)
 534                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 535                 if (type != OBJ_BLOB)
 536                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 537                 if (S_ISREG(mode)) {
 538                         struct strbuf strbuf = STRBUF_INIT;
 539                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
 540                                 free(buf);
 541                                 size = strbuf.len;
 542                                 buf = strbuf_detach(&strbuf, NULL);
 543                         }
 544                 }
 545
 546                 if (make_room_for_path(path) < 0) {
 547                         update_wd = 0;
 548                         free(buf);
 549                         goto update_index;
 550                 }
 551                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 552                         int fd;
 553                         if (mode & 0100)
 554                                 mode = 0777;
 555                         else
 556                                 mode = 0666;
 557                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 558                         if (fd < 0)
 559                                 die_errno("failed to open '%s'", path);
 560                         flush_buffer(fd, buf, size);
 561                         close(fd);
 562                 } else if (S_ISLNK(mode)) {
 563                         char *lnk = xmemdupz(buf, size);
 564                         safe_create_leading_directories_const(path);
 565                         unlink(path);
 566                         if (symlink(lnk, path))
 567                                 die_errno("failed to symlink '%s'", path);
 568                         free(lnk);
 569                 } else
 570                         die("do not know what to do with %06o %s '%s'",
 571                             mode, sha1_to_hex(sha), path);
 572                 free(buf);
 573         }
 574  update_index:
 575         if (update_cache)
 576                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 577 }
 578
 579 static void update_file(struct merge_options *o,
 580                         int clean,
 581                         const unsigned char *sha,
 582                         unsigned mode,
 583                         const char *path)
 584 {
 585         update_file_flags(o, sha, mode, path, o->call_depth || clean, !o->call_depth);
 586 }
 587
 588 /* Low level file merging, update and removal */
 589
 590 struct merge_file_info
 591 {
 592         unsigned char sha[20];
 593         unsigned mode;
 594         unsigned clean:1,
 595                  merge:1;
 596 };
 597
 598 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 599 {
 600         unsigned long size;
 601         enum object_type type;
 602
 603         if (!hashcmp(sha1, null_sha1)) {
 604                 mm->ptr = xstrdup("");
 605                 mm->size = 0;
 606                 return;
 607         }
 608
 609         mm->ptr = read_sha1_file(sha1, &type, &size);
 610         if (!mm->ptr || type != OBJ_BLOB)
 611                 die("unable to read blob object %s", sha1_to_hex(sha1));
 612         mm->size = size;
 613 }
 614
 615 static int merge_3way(struct merge_options *o,
 616                       mmbuffer_t *result_buf,
 617                       struct diff_filespec *one,
 618                       struct diff_filespec *a,
 619                       struct diff_filespec *b,
 620                       const char *branch1,
 621                       const char *branch2)
 622 {
 623         mmfile_t orig, src1, src2;
 624         char *name1, *name2;
 625         int merge_status;
 626
 627         if (strcmp(a->path, b->path)) {
 628                 name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 629                 name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 630         } else {
 631                 name1 = xstrdup(mkpath("%s", branch1));
 632                 name2 = xstrdup(mkpath("%s", branch2));
 633         }
 634
 635         fill_mm(one->sha1, &orig);
 636         fill_mm(a->sha1, &src1);
 637         fill_mm(b->sha1, &src2);
 638
 639         merge_status = ll_merge(result_buf, a->path, &orig,
 640                                 &src1, name1, &src2, name2,
 641                                 o->call_depth);
 642
 643         free(name1);
 644         free(name2);
 645         free(orig.ptr);
 646         free(src1.ptr);
 647         free(src2.ptr);
 648         return merge_status;
 649 }
 650
 651 static struct merge_file_info merge_file(struct merge_options *o,
 652                                          struct diff_filespec *one,
 653                                          struct diff_filespec *a,
 654                                          struct diff_filespec *b,
 655                                          const char *branch1,
 656                                          const char *branch2)
 657 {
 658         struct merge_file_info result;
 659         result.merge = 0;
 660         result.clean = 1;
 661
 662         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 663                 result.clean = 0;
 664                 if (S_ISREG(a->mode)) {
 665                         result.mode = a->mode;
 666                         hashcpy(result.sha, a->sha1);
 667                 } else {
 668                         result.mode = b->mode;
 669                         hashcpy(result.sha, b->sha1);
 670                 }
 671         } else {
 672                 if (!sha_eq(a->sha1, one->sha1) && !sha_eq(b->sha1, one->sha1))
 673                         result.merge = 1;
 674
 675                 /*
 676                  * Merge modes
 677                  */
 678                 if (a->mode == b->mode || a->mode == one->mode)
 679                         result.mode = b->mode;
 680                 else {
 681                         result.mode = a->mode;
 682                         if (b->mode != one->mode) {
 683                                 result.clean = 0;
 684                                 result.merge = 1;
 685                         }
 686                 }
 687
 688                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, one->sha1))
 689                         hashcpy(result.sha, b->sha1);
 690                 else if (sha_eq(b->sha1, one->sha1))
 691                         hashcpy(result.sha, a->sha1);
 692                 else if (S_ISREG(a->mode)) {
 693                         mmbuffer_t result_buf;
 694                         int merge_status;
 695
 696                         merge_status = merge_3way(o, &result_buf, one, a, b,
 697                                                   branch1, branch2);
 698
 699                         if ((merge_status < 0) || !result_buf.ptr)
 700                                 die("Failed to execute internal merge");
 701
 702                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 703                                             blob_type, result.sha))
 704                                 die("Unable to add %s to database",
 705                                     a->path);
 706
 707                         free(result_buf.ptr);
 708                         result.clean = (merge_status == 0);
 709                 } else if (S_ISGITLINK(a->mode)) {
 710                         result.clean = 0;
 711                         hashcpy(result.sha, a->sha1);
 712                 } else if (S_ISLNK(a->mode)) {
 713                         hashcpy(result.sha, a->sha1);
 714
 715                         if (!sha_eq(a->sha1, b->sha1))
 716                                 result.clean = 0;
 717                 } else {
 718                         die("unsupported object type in the tree");
 719                 }
 720         }
 721
 722         return result;
 723 }
 724
 725 static void conflict_rename_rename(struct merge_options *o,
 726                                    struct rename *ren1,
 727                                    const char *branch1,
 728                                    struct rename *ren2,
 729                                    const char *branch2)
 730 {
 731         char *del[2];
 732         int delp = 0;
 733         const char *ren1_dst = ren1->pair->two->path;
 734         const char *ren2_dst = ren2->pair->two->path;
 735         const char *dst_name1 = ren1_dst;
 736         const char *dst_name2 = ren2_dst;
 737         if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
 738                 dst_name1 = del[delp++] = unique_path(o, ren1_dst, branch1);
 739                 output(o, 1, "%s is a directory in %s adding as %s instead",
 740                        ren1_dst, branch2, dst_name1);
 741                 remove_file(o, 0, ren1_dst, 0);
 742         }
 743         if (string_list_has_string(&o->current_directory_set, ren2_dst)) {
 744                 dst_name2 = del[delp++] = unique_path(o, ren2_dst, branch2);
 745                 output(o, 1, "%s is a directory in %s adding as %s instead",
 746                        ren2_dst, branch1, dst_name2);
 747                 remove_file(o, 0, ren2_dst, 0);
 748         }
 749         if (o->call_depth) {
 750                 remove_file_from_cache(dst_name1);
 751                 remove_file_from_cache(dst_name2);
 752                 /*
 753                  * Uncomment to leave the conflicting names in the resulting tree
 754                  *
 755                  * update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
 756                  * update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
 757                  */
 758         } else {
 759                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
 760                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
 761         }
 762         while (delp--)
 763                 free(del[delp]);
 764 }
 765
 766 static void conflict_rename_dir(struct merge_options *o,
 767                                 struct rename *ren1,
 768                                 const char *branch1)
 769 {
 770         char *new_path = unique_path(o, ren1->pair->two->path, branch1);
 771         output(o, 1, "Renaming %s to %s instead", ren1->pair->one->path, new_path);
 772         remove_file(o, 0, ren1->pair->two->path, 0);
 773         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
 774         free(new_path);
 775 }
 776
 777 static void conflict_rename_rename_2(struct merge_options *o,
 778                                      struct rename *ren1,
 779                                      const char *branch1,
 780                                      struct rename *ren2,
 781                                      const char *branch2)
 782 {
 783         char *new_path1 = unique_path(o, ren1->pair->two->path, branch1);
 784         char *new_path2 = unique_path(o, ren2->pair->two->path, branch2);
 785         output(o, 1, "Renaming %s to %s and %s to %s instead",
 786                ren1->pair->one->path, new_path1,
 787                ren2->pair->one->path, new_path2);
 788         remove_file(o, 0, ren1->pair->two->path, 0);
 789         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 790         update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 791         free(new_path2);
 792         free(new_path1);
 793 }
 794
 795 static int process_renames(struct merge_options *o,
 796                            struct string_list *a_renames,
 797                            struct string_list *b_renames)
 798 {
 799         int clean_merge = 1, i, j;
 800         struct string_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
 801         const struct rename *sre;
 802
 803         for (i = 0; i < a_renames->nr; i++) {
 804                 sre = a_renames->items[i].util;
 805                 string_list_insert(sre->pair->two->path, &a_by_dst)->util
 806                         = sre->dst_entry;
 807         }
 808         for (i = 0; i < b_renames->nr; i++) {
 809                 sre = b_renames->items[i].util;
 810                 string_list_insert(sre->pair->two->path, &b_by_dst)->util
 811                         = sre->dst_entry;
 812         }
 813
 814         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 815                 char *src;
 816                 struct string_list *renames1, *renames2Dst;
 817                 struct rename *ren1 = NULL, *ren2 = NULL;
 818                 const char *branch1, *branch2;
 819                 const char *ren1_src, *ren1_dst;
 820
 821                 if (i >= a_renames->nr) {
 822                         ren2 = b_renames->items[j++].util;
 823                 } else if (j >= b_renames->nr) {
 824                         ren1 = a_renames->items[i++].util;
 825                 } else {
 826                         int compare = strcmp(a_renames->items[i].string,
 827                                              b_renames->items[j].string);
 828                         if (compare <= 0)
 829                                 ren1 = a_renames->items[i++].util;
 830                         if (compare >= 0)
 831                                 ren2 = b_renames->items[j++].util;
 832                 }
 833
 834                 /* TODO: refactor, so that 1/2 are not needed */
 835                 if (ren1) {
 836                         renames1 = a_renames;
 837                         renames2Dst = &b_by_dst;
 838                         branch1 = o->branch1;
 839                         branch2 = o->branch2;
 840                 } else {
 841                         struct rename *tmp;
 842                         renames1 = b_renames;
 843                         renames2Dst = &a_by_dst;
 844                         branch1 = o->branch2;
 845                         branch2 = o->branch1;
 846                         tmp = ren2;
 847                         ren2 = ren1;
 848                         ren1 = tmp;
 849                 }
 850                 src = ren1->pair->one->path;
 851
 852                 ren1->dst_entry->processed = 1;
 853                 ren1->src_entry->processed = 1;
 854
 855                 if (ren1->processed)
 856                         continue;
 857                 ren1->processed = 1;
 858
 859                 ren1_src = ren1->pair->one->path;
 860                 ren1_dst = ren1->pair->two->path;
 861
 862                 if (ren2) {
 863                         const char *ren2_src = ren2->pair->one->path;
 864                         const char *ren2_dst = ren2->pair->two->path;
 865                         /* Renamed in 1 and renamed in 2 */
 866                         if (strcmp(ren1_src, ren2_src) != 0)
 867                                 die("ren1.src != ren2.src");
 868                         ren2->dst_entry->processed = 1;
 869                         ren2->processed = 1;
 870                         if (strcmp(ren1_dst, ren2_dst) != 0) {
 871                                 clean_merge = 0;
 872                                 output(o, 1, "CONFLICT (rename/rename): "
 873                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
 874                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
 875                                        src, ren1_dst, branch1,
 876                                        src, ren2_dst, branch2,
 877                                        o->call_depth ? " (left unresolved)": "");
 878                                 if (o->call_depth) {
 879                                         remove_file_from_cache(src);
 880                                         update_file(o, 0, ren1->pair->one->sha1,
 881                                                     ren1->pair->one->mode, src);
 882                                 }
 883                                 conflict_rename_rename(o, ren1, branch1, ren2, branch2);
 884                         } else {
 885                                 struct merge_file_info mfi;
 886                                 remove_file(o, 1, ren1_src, 1);
 887                                 mfi = merge_file(o,
 888                                                  ren1->pair->one,
 889                                                  ren1->pair->two,
 890                                                  ren2->pair->two,
 891                                                  branch1,
 892                                                  branch2);
 893                                 if (mfi.merge || !mfi.clean)
 894                                         output(o, 1, "Renaming %s->%s", src, ren1_dst);
 895
 896                                 if (mfi.merge)
 897                                         output(o, 2, "Auto-merging %s", ren1_dst);
 898
 899                                 if (!mfi.clean) {
 900                                         output(o, 1, "CONFLICT (content): merge conflict in %s",
 901                                                ren1_dst);
 902                                         clean_merge = 0;
 903
 904                                         if (!o->call_depth)
 905                                                 update_stages(ren1_dst,
 906                                                               ren1->pair->one,
 907                                                               ren1->pair->two,
 908                                                               ren2->pair->two,
 909                                                               1 /* clear */);
 910                                 }
 911                                 update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 912                         }
 913                 } else {
 914                         /* Renamed in 1, maybe changed in 2 */
 915                         struct string_list_item *item;
 916                         /* we only use sha1 and mode of these */
 917                         struct diff_filespec src_other, dst_other;
 918                         int try_merge, stage = a_renames == renames1 ? 3: 2;
 919
 920                         remove_file(o, 1, ren1_src, o->call_depth || stage == 3);
 921
 922                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
 923                         src_other.mode = ren1->src_entry->stages[stage].mode;
 924                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
 925                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
 926
 927                         try_merge = 0;
 928
 929                         if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
 930                                 clean_merge = 0;
 931                                 output(o, 1, "CONFLICT (rename/directory): Rename %s->%s in %s "
 932                                        " directory %s added in %s",
 933                                        ren1_src, ren1_dst, branch1,
 934                                        ren1_dst, branch2);
 935                                 conflict_rename_dir(o, ren1, branch1);
 936                         } else if (sha_eq(src_other.sha1, null_sha1)) {
 937                                 clean_merge = 0;
 938                                 output(o, 1, "CONFLICT (rename/delete): Rename %s->%s in %s "
 939                                        "and deleted in %s",
 940                                        ren1_src, ren1_dst, branch1,
 941                                        branch2);
 942                                 update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
 943                                 if (!o->call_depth)
 944                                         update_stages(ren1_dst, NULL,
 945                                                         branch1 == o->branch1 ?
 946                                                         ren1->pair->two : NULL,
 947                                                         branch1 == o->branch1 ?
 948                                                         NULL : ren1->pair->two, 1);
 949                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
 950                                 const char *new_path;
 951                                 clean_merge = 0;
 952                                 try_merge = 1;
 953                                 output(o, 1, "CONFLICT (rename/add): Rename %s->%s in %s. "
 954                                        "%s added in %s",
 955                                        ren1_src, ren1_dst, branch1,
 956                                        ren1_dst, branch2);
 957                                 if (o->call_depth) {
 958                                         struct merge_file_info mfi;
 959                                         struct diff_filespec one, a, b;
 960
 961                                         one.path = a.path = b.path =
 962                                                 (char *)ren1_dst;
 963                                         hashcpy(one.sha1, null_sha1);
 964                                         one.mode = 0;
 965                                         hashcpy(a.sha1, ren1->pair->two->sha1);
 966                                         a.mode = ren1->pair->two->mode;
 967                                         hashcpy(b.sha1, dst_other.sha1);
 968                                         b.mode = dst_other.mode;
 969                                         mfi = merge_file(o, &one, &a, &b,
 970                                                          branch1,
 971                                                          branch2);
 972                                         output(o, 1, "Adding merged %s", ren1_dst);
 973                                         update_file(o, 0,
 974                                                     mfi.sha,
 975                                                     mfi.mode,
 976                                                     ren1_dst);
 977                                 } else {
 978                                         new_path = unique_path(o, ren1_dst, branch2);
 979                                         output(o, 1, "Adding as %s instead", new_path);
 980                                         update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
 981                                 }
 982                         } else if ((item = string_list_lookup(ren1_dst, renames2Dst))) {
 983                                 ren2 = item->util;
 984                                 clean_merge = 0;
 985                                 ren2->processed = 1;
 986                                 output(o, 1, "CONFLICT (rename/rename): "
 987                                        "Rename %s->%s in %s. "
 988                                        "Rename %s->%s in %s",
 989                                        ren1_src, ren1_dst, branch1,
 990                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
 991                                 conflict_rename_rename_2(o, ren1, branch1, ren2, branch2);
 992                         } else
 993                                 try_merge = 1;
 994
 995                         if (try_merge) {
 996                                 struct diff_filespec *one, *a, *b;
 997                                 struct merge_file_info mfi;
 998                                 src_other.path = (char *)ren1_src;
 999
1000                                 one = ren1->pair->one;
1001                                 if (a_renames == renames1) {
1002                                         a = ren1->pair->two;
1003                                         b = &src_other;
1004                                 } else {
1005                                         b = ren1->pair->two;
1006                                         a = &src_other;
1007                                 }
1008                                 mfi = merge_file(o, one, a, b,
1009                                                 o->branch1, o->branch2);
1010
1011                                 if (mfi.clean &&
1012                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
1013                                     mfi.mode == ren1->pair->two->mode)
1014                                         /*
1015                                          * This messaged is part of
1016                                          * t6022 test. If you change
1017                                          * it update the test too.
1018                                          */
1019                                         output(o, 3, "Skipped %s (merged same as existing)", ren1_dst);
1020                                 else {
1021                                         if (mfi.merge || !mfi.clean)
1022                                                 output(o, 1, "Renaming %s => %s", ren1_src, ren1_dst);
1023                                         if (mfi.merge)
1024                                                 output(o, 2, "Auto-merging %s", ren1_dst);
1025                                         if (!mfi.clean) {
1026                                                 output(o, 1, "CONFLICT (rename/modify): Merge conflict in %s",
1027                                                        ren1_dst);
1028                                                 clean_merge = 0;
1029
1030                                                 if (!o->call_depth)
1031                                                         update_stages(ren1_dst,
1032                                                                       one, a, b, 1);
1033                                         }
1034                                         update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1035                                 }
1036                         }
1037                 }
1038         }
1039         string_list_clear(&a_by_dst, 0);
1040         string_list_clear(&b_by_dst, 0);
1041
1042         return clean_merge;
1043 }
1044
1045 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1046 {
1047         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1048 }
1049
1050 /* Per entry merge function */
1051 static int process_entry(struct merge_options *o,
1052                          const char *path, struct stage_data *entry)
1053 {
1054         /*
1055         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1056         print_index_entry("\tpath: ", entry);
1057         */
1058         int clean_merge = 1;
1059         unsigned o_mode = entry->stages[1].mode;
1060         unsigned a_mode = entry->stages[2].mode;
1061         unsigned b_mode = entry->stages[3].mode;
1062         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1063         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1064         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1065
1066         if (o_sha && (!a_sha || !b_sha)) {
1067                 /* Case A: Deleted in one */
1068                 if ((!a_sha && !b_sha) ||
1069                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1070                     (!a_sha && sha_eq(b_sha, o_sha))) {
1071                         /* Deleted in both or deleted in one and
1072                          * unchanged in the other */
1073                         if (a_sha)
1074                                 output(o, 2, "Removing %s", path);
1075                         /* do not touch working file if it did not exist */
1076                         remove_file(o, 1, path, !a_sha);
1077                 } else {
1078                         /* Deleted in one and changed in the other */
1079                         clean_merge = 0;
1080                         if (!a_sha) {
1081                                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1082                                        "and modified in %s. Version %s of %s left in tree.",
1083                                        path, o->branch1,
1084                                        o->branch2, o->branch2, path);
1085                                 update_file(o, 0, b_sha, b_mode, path);
1086                         } else {
1087                                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1088                                        "and modified in %s. Version %s of %s left in tree.",
1089                                        path, o->branch2,
1090                                        o->branch1, o->branch1, path);
1091                                 update_file(o, 0, a_sha, a_mode, path);
1092                         }
1093                 }
1094
1095         } else if ((!o_sha && a_sha && !b_sha) ||
1096                    (!o_sha && !a_sha && b_sha)) {
1097                 /* Case B: Added in one. */
1098                 const char *add_branch;
1099                 const char *other_branch;
1100                 unsigned mode;
1101                 const unsigned char *sha;
1102                 const char *conf;
1103
1104                 if (a_sha) {
1105                         add_branch = o->branch1;
1106                         other_branch = o->branch2;
1107                         mode = a_mode;
1108                         sha = a_sha;
1109                         conf = "file/directory";
1110                 } else {
1111                         add_branch = o->branch2;
1112                         other_branch = o->branch1;
1113                         mode = b_mode;
1114                         sha = b_sha;
1115                         conf = "directory/file";
1116                 }
1117                 if (string_list_has_string(&o->current_directory_set, path)) {
1118                         const char *new_path = unique_path(o, path, add_branch);
1119                         clean_merge = 0;
1120                         output(o, 1, "CONFLICT (%s): There is a directory with name %s in %s. "
1121                                "Adding %s as %s",
1122                                conf, path, other_branch, path, new_path);
1123                         remove_file(o, 0, path, 0);
1124                         update_file(o, 0, sha, mode, new_path);
1125                 } else {
1126                         output(o, 2, "Adding %s", path);
1127                         update_file(o, 1, sha, mode, path);
1128                 }
1129         } else if (a_sha && b_sha) {
1130                 /* Case C: Added in both (check for same permissions) and */
1131                 /* case D: Modified in both, but differently. */
1132                 const char *reason = "content";
1133                 struct merge_file_info mfi;
1134                 struct diff_filespec one, a, b;
1135
1136                 if (!o_sha) {
1137                         reason = "add/add";
1138                         o_sha = (unsigned char *)null_sha1;
1139                 }
1140                 output(o, 2, "Auto-merging %s", path);
1141                 one.path = a.path = b.path = (char *)path;
1142                 hashcpy(one.sha1, o_sha);
1143                 one.mode = o_mode;
1144                 hashcpy(a.sha1, a_sha);
1145                 a.mode = a_mode;
1146                 hashcpy(b.sha1, b_sha);
1147                 b.mode = b_mode;
1148
1149                 mfi = merge_file(o, &one, &a, &b,
1150                                  o->branch1, o->branch2);
1151
1152                 clean_merge = mfi.clean;
1153                 if (!mfi.clean) {
1154                         if (S_ISGITLINK(mfi.mode))
1155                                 reason = "submodule";
1156                         output(o, 1, "CONFLICT (%s): Merge conflict in %s",
1157                                         reason, path);
1158                 }
1159                 update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
1160         } else if (!o_sha && !a_sha && !b_sha) {
1161                 /*
1162                  * this entry was deleted altogether. a_mode == 0 means
1163                  * we had that path and want to actively remove it.
1164                  */
1165                 remove_file(o, 1, path, !a_mode);
1166         } else
1167                 die("Fatal merge failure, shouldn't happen.");
1168
1169         return clean_merge;
1170 }
1171
1172 struct unpack_trees_error_msgs get_porcelain_error_msgs(void)
1173 {
1174         struct unpack_trees_error_msgs msgs = {
1175                 /* would_overwrite */
1176                 "Your local changes to '%s' would be overwritten by merge.  Aborting.",
1177                 /* not_uptodate_file */
1178                 "Your local changes to '%s' would be overwritten by merge.  Aborting.",
1179                 /* not_uptodate_dir */
1180                 "Updating '%s' would lose untracked files in it.  Aborting.",
1181                 /* would_lose_untracked */
1182                 "Untracked working tree file '%s' would be %s by merge.  Aborting",
1183                 /* bind_overlap -- will not happen here */
1184                 NULL,
1185         };
1186         if (advice_commit_before_merge) {
1187                 msgs.would_overwrite = msgs.not_uptodate_file =
1188                         "Your local changes to '%s' would be overwritten by merge.  Aborting.\n"
1189                         "Please, commit your changes or stash them before you can merge.";
1190         }
1191         return msgs;
1192 }
1193
1194 int merge_trees(struct merge_options *o,
1195                 struct tree *head,
1196                 struct tree *merge,
1197                 struct tree *common,
1198                 struct tree **result)
1199 {
1200         int code, clean;
1201
1202         if (o->subtree_merge) {
1203                 merge = shift_tree_object(head, merge);
1204                 common = shift_tree_object(head, common);
1205         }
1206
1207         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1208                 output(o, 0, "Already uptodate!");
1209                 *result = head;
1210                 return 1;
1211         }
1212
1213         code = git_merge_trees(o->call_depth, common, head, merge);
1214
1215         if (code != 0) {
1216                 if (show(o, 4) || o->call_depth)
1217                         die("merging of trees %s and %s failed",
1218                             sha1_to_hex(head->object.sha1),
1219                             sha1_to_hex(merge->object.sha1));
1220                 else
1221                         exit(128);
1222         }
1223
1224         if (unmerged_cache()) {
1225                 struct string_list *entries, *re_head, *re_merge;
1226                 int i;
1227                 string_list_clear(&o->current_file_set, 1);
1228                 string_list_clear(&o->current_directory_set, 1);
1229                 get_files_dirs(o, head);
1230                 get_files_dirs(o, merge);
1231
1232                 entries = get_unmerged();
1233                 re_head  = get_renames(o, head, common, head, merge, entries);
1234                 re_merge = get_renames(o, merge, common, head, merge, entries);
1235                 clean = process_renames(o, re_head, re_merge);
1236                 for (i = 0; i < entries->nr; i++) {
1237                         const char *path = entries->items[i].string;
1238                         struct stage_data *e = entries->items[i].util;
1239                         if (!e->processed
1240                                 && !process_entry(o, path, e))
1241                                 clean = 0;
1242                 }
1243
1244                 string_list_clear(re_merge, 0);
1245                 string_list_clear(re_head, 0);
1246                 string_list_clear(entries, 1);
1247
1248         }
1249         else
1250                 clean = 1;
1251
1252         if (o->call_depth)
1253                 *result = write_tree_from_memory(o);
1254
1255         return clean;
1256 }
1257
1258 static struct commit_list *reverse_commit_list(struct commit_list *list)
1259 {
1260         struct commit_list *next = NULL, *current, *backup;
1261         for (current = list; current; current = backup) {
1262                 backup = current->next;
1263                 current->next = next;
1264                 next = current;
1265         }
1266         return next;
1267 }
1268
1269 /*
1270  * Merge the commits h1 and h2, return the resulting virtual
1271  * commit object and a flag indicating the cleanness of the merge.
1272  */
1273 int merge_recursive(struct merge_options *o,
1274                     struct commit *h1,
1275                     struct commit *h2,
1276                     struct commit_list *ca,
1277                     struct commit **result)
1278 {
1279         struct commit_list *iter;
1280         struct commit *merged_common_ancestors;
1281         struct tree *mrtree = mrtree;
1282         int clean;
1283
1284         if (show(o, 4)) {
1285                 output(o, 4, "Merging:");
1286                 output_commit_title(o, h1);
1287                 output_commit_title(o, h2);
1288         }
1289
1290         if (!ca) {
1291                 ca = get_merge_bases(h1, h2, 1);
1292                 ca = reverse_commit_list(ca);
1293         }
1294
1295         if (show(o, 5)) {
1296                 output(o, 5, "found %u common ancestor(s):", commit_list_count(ca));
1297                 for (iter = ca; iter; iter = iter->next)
1298                         output_commit_title(o, iter->item);
1299         }
1300
1301         merged_common_ancestors = pop_commit(&ca);
1302         if (merged_common_ancestors == NULL) {
1303                 /* if there is no common ancestor, make an empty tree */
1304                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1305
1306                 tree->object.parsed = 1;
1307                 tree->object.type = OBJ_TREE;
1308                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1309                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1310         }
1311
1312         for (iter = ca; iter; iter = iter->next) {
1313                 const char *saved_b1, *saved_b2;
1314                 o->call_depth++;
1315                 /*
1316                  * When the merge fails, the result contains files
1317                  * with conflict markers. The cleanness flag is
1318                  * ignored, it was never actually used, as result of
1319                  * merge_trees has always overwritten it: the committed
1320                  * "conflicts" were already resolved.
1321                  */
1322                 discard_cache();
1323                 saved_b1 = o->branch1;
1324                 saved_b2 = o->branch2;
1325                 o->branch1 = "Temporary merge branch 1";
1326                 o->branch2 = "Temporary merge branch 2";
1327                 merge_recursive(o, merged_common_ancestors, iter->item,
1328                                 NULL, &merged_common_ancestors);
1329                 o->branch1 = saved_b1;
1330                 o->branch2 = saved_b2;
1331                 o->call_depth--;
1332
1333                 if (!merged_common_ancestors)
1334                         die("merge returned no commit");
1335         }
1336
1337         discard_cache();
1338         if (!o->call_depth)
1339                 read_cache();
1340
1341         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
1342                             &mrtree);
1343
1344         if (o->call_depth) {
1345                 *result = make_virtual_commit(mrtree, "merged tree");
1346                 commit_list_insert(h1, &(*result)->parents);
1347                 commit_list_insert(h2, &(*result)->parents->next);
1348         }
1349         flush_output(o);
1350         return clean;
1351 }
1352
1353 static struct commit *get_ref(const unsigned char *sha1, const char *name)
1354 {
1355         struct object *object;
1356
1357         object = deref_tag(parse_object(sha1), name, strlen(name));
1358         if (!object)
1359                 return NULL;
1360         if (object->type == OBJ_TREE)
1361                 return make_virtual_commit((struct tree*)object, name);
1362         if (object->type != OBJ_COMMIT)
1363                 return NULL;
1364         if (parse_commit((struct commit *)object))
1365                 return NULL;
1366         return (struct commit *)object;
1367 }
1368
1369 int merge_recursive_generic(struct merge_options *o,
1370                             const unsigned char *head,
1371                             const unsigned char *merge,
1372                             int num_base_list,
1373                             const unsigned char **base_list,
1374                             struct commit **result)
1375 {
1376         int clean, index_fd;
1377         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1378         struct commit *head_commit = get_ref(head, o->branch1);
1379         struct commit *next_commit = get_ref(merge, o->branch2);
1380         struct commit_list *ca = NULL;
1381
1382         if (base_list) {
1383                 int i;
1384                 for (i = 0; i < num_base_list; ++i) {
1385                         struct commit *base;
1386                         if (!(base = get_ref(base_list[i], sha1_to_hex(base_list[i]))))
1387                                 return error("Could not parse object '%s'",
1388                                         sha1_to_hex(base_list[i]));
1389                         commit_list_insert(base, &ca);
1390                 }
1391         }
1392
1393         index_fd = hold_locked_index(lock, 1);
1394         clean = merge_recursive(o, head_commit, next_commit, ca,
1395                         result);
1396         if (active_cache_changed &&
1397                         (write_cache(index_fd, active_cache, active_nr) ||
1398                          commit_locked_index(lock)))
1399                 return error("Unable to write index.");
1400
1401         return clean ? 0 : 1;
1402 }
1403
1404 static int merge_recursive_config(const char *var, const char *value, void *cb)
1405 {
1406         struct merge_options *o = cb;
1407         if (!strcasecmp(var, "merge.verbosity")) {
1408                 o->verbosity = git_config_int(var, value);
1409                 return 0;
1410         }
1411         if (!strcasecmp(var, "diff.renamelimit")) {
1412                 o->diff_rename_limit = git_config_int(var, value);
1413                 return 0;
1414         }
1415         if (!strcasecmp(var, "merge.renamelimit")) {
1416                 o->merge_rename_limit = git_config_int(var, value);
1417                 return 0;
1418         }
1419         return git_xmerge_config(var, value, cb);
1420 }
1421
1422 void init_merge_options(struct merge_options *o)
1423 {
1424         memset(o, 0, sizeof(struct merge_options));
1425         o->verbosity = 2;
1426         o->buffer_output = 1;
1427         o->diff_rename_limit = -1;
1428         o->merge_rename_limit = -1;
1429         git_config(merge_recursive_config, o);
1430         if (getenv("GIT_MERGE_VERBOSITY"))
1431                 o->verbosity =
1432                         strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1433         if (o->verbosity >= 5)
1434                 o->buffer_output = 0;
1435         strbuf_init(&o->obuf, 0);
1436         memset(&o->current_file_set, 0, sizeof(struct string_list));
1437         o->current_file_set.strdup_strings = 1;
1438         memset(&o->current_directory_set, 0, sizeof(struct string_list));
1439         o->current_directory_set.strdup_strings = 1;
1440 }