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 "cache-tree.h"
   8 #include "commit.h"
   9 #include "blob.h"
  10 #include "tree-walk.h"
  11 #include "diff.h"
  12 #include "diffcore.h"
  13 #include "run-command.h"
  14 #include "tag.h"
  15 #include "unpack-trees.h"
  16 #include "path-list.h"
  17 #include "xdiff-interface.h"
  18
  19 static int subtree_merge;
  20
  21 static struct tree *shift_tree_object(struct tree *one, struct tree *two)
  22 {
  23         unsigned char shifted[20];
  24
  25         /*
  26          * NEEDSWORK: this limits the recursion depth to hardcoded
  27          * value '2' to avoid excessive overhead.
  28          */
  29         shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
  30         if (!hashcmp(two->object.sha1, shifted))
  31                 return two;
  32         return lookup_tree(shifted);
  33 }
  34
  35 /*
  36  * A virtual commit has
  37  * - (const char *)commit->util set to the name, and
  38  * - *(int *)commit->object.sha1 set to the virtual id.
  39  */
  40
  41 static unsigned commit_list_count(const struct commit_list *l)
  42 {
  43         unsigned c = 0;
  44         for (; l; l = l->next )
  45                 c++;
  46         return c;
  47 }
  48
  49 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  50 {
  51         struct commit *commit = xcalloc(1, sizeof(struct commit));
  52         static unsigned virtual_id = 1;
  53         commit->tree = tree;
  54         commit->util = (void*)comment;
  55         *(int*)commit->object.sha1 = virtual_id++;
  56         /* avoid warnings */
  57         commit->object.parsed = 1;
  58         return commit;
  59 }
  60
  61 /*
  62  * Since we use get_tree_entry(), which does not put the read object into
  63  * the object pool, we cannot rely on a == b.
  64  */
  65 static int sha_eq(const unsigned char *a, const unsigned char *b)
  66 {
  67         if (!a && !b)
  68                 return 2;
  69         return a && b && hashcmp(a, b) == 0;
  70 }
  71
  72 /*
  73  * Since we want to write the index eventually, we cannot reuse the index
  74  * for these (temporary) data.
  75  */
  76 struct stage_data
  77 {
  78         struct
  79         {
  80                 unsigned mode;
  81                 unsigned char sha[20];
  82         } stages[4];
  83         unsigned processed:1;
  84 };
  85
  86 struct output_buffer
  87 {
  88         struct output_buffer *next;
  89         char *str;
  90 };
  91
  92 static struct path_list current_file_set = {NULL, 0, 0, 1};
  93 static struct path_list current_directory_set = {NULL, 0, 0, 1};
  94
  95 static int call_depth = 0;
  96 static int verbosity = 2;
  97 static int buffer_output = 1;
  98 static int do_progress = 1;
  99 static unsigned last_percent;
 100 static unsigned merged_cnt;
 101 static unsigned total_cnt;
 102 static volatile sig_atomic_t progress_update;
 103 static struct output_buffer *output_list, *output_end;
 104
 105 static int show (int v)
 106 {
 107         return (!call_depth && verbosity >= v) || verbosity >= 5;
 108 }
 109
 110 static void output(int v, const char *fmt, ...)
 111 {
 112         va_list args;
 113         va_start(args, fmt);
 114         if (buffer_output && show(v)) {
 115                 struct output_buffer *b = xmalloc(sizeof(*b));
 116                 nfvasprintf(&b->str, fmt, args);
 117                 b->next = NULL;
 118                 if (output_end)
 119                         output_end->next = b;
 120                 else
 121                         output_list = b;
 122                 output_end = b;
 123         } else if (show(v)) {
 124                 int i;
 125                 for (i = call_depth; i--;)
 126                         fputs("  ", stdout);
 127                 vfprintf(stdout, fmt, args);
 128                 fputc('\n', stdout);
 129         }
 130         va_end(args);
 131 }
 132
 133 static void flush_output()
 134 {
 135         struct output_buffer *b, *n;
 136         for (b = output_list; b; b = n) {
 137                 int i;
 138                 for (i = call_depth; i--;)
 139                         fputs("  ", stdout);
 140                 fputs(b->str, stdout);
 141                 fputc('\n', stdout);
 142                 n = b->next;
 143                 free(b->str);
 144                 free(b);
 145         }
 146         output_list = NULL;
 147         output_end = NULL;
 148 }
 149
 150 static void output_commit_title(struct commit *commit)
 151 {
 152         int i;
 153         flush_output();
 154         for (i = call_depth; i--;)
 155                 fputs("  ", stdout);
 156         if (commit->util)
 157                 printf("virtual %s\n", (char *)commit->util);
 158         else {
 159                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 160                 if (parse_commit(commit) != 0)
 161                         printf("(bad commit)\n");
 162                 else {
 163                         const char *s;
 164                         int len;
 165                         for (s = commit->buffer; *s; s++)
 166                                 if (*s == '\n' && s[1] == '\n') {
 167                                         s += 2;
 168                                         break;
 169                                 }
 170                         for (len = 0; s[len] && '\n' != s[len]; len++)
 171                                 ; /* do nothing */
 172                         printf("%.*s\n", len, s);
 173                 }
 174         }
 175 }
 176
 177 static void progress_interval(int signum)
 178 {
 179         progress_update = 1;
 180 }
 181
 182 static void setup_progress_signal(void)
 183 {
 184         struct sigaction sa;
 185         struct itimerval v;
 186
 187         memset(&sa, 0, sizeof(sa));
 188         sa.sa_handler = progress_interval;
 189         sigemptyset(&sa.sa_mask);
 190         sa.sa_flags = SA_RESTART;
 191         sigaction(SIGALRM, &sa, NULL);
 192
 193         v.it_interval.tv_sec = 1;
 194         v.it_interval.tv_usec = 0;
 195         v.it_value = v.it_interval;
 196         setitimer(ITIMER_REAL, &v, NULL);
 197 }
 198
 199 static void display_progress()
 200 {
 201         unsigned percent = total_cnt ? merged_cnt * 100 / total_cnt : 0;
 202         if (progress_update || percent != last_percent) {
 203                 fprintf(stderr, "%4u%% (%u/%u) done\r",
 204                         percent, merged_cnt, total_cnt);
 205                 progress_update = 0;
 206                 last_percent = percent;
 207         }
 208 }
 209
 210 static struct cache_entry *make_cache_entry(unsigned int mode,
 211                 const unsigned char *sha1, const char *path, int stage, int refresh)
 212 {
 213         int size, len;
 214         struct cache_entry *ce;
 215
 216         if (!verify_path(path))
 217                 return NULL;
 218
 219         len = strlen(path);
 220         size = cache_entry_size(len);
 221         ce = xcalloc(1, size);
 222
 223         hashcpy(ce->sha1, sha1);
 224         memcpy(ce->name, path, len);
 225         ce->ce_flags = create_ce_flags(len, stage);
 226         ce->ce_mode = create_ce_mode(mode);
 227
 228         if (refresh)
 229                 return refresh_cache_entry(ce, 0);
 230
 231         return ce;
 232 }
 233
 234 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 235                 const char *path, int stage, int refresh, int options)
 236 {
 237         struct cache_entry *ce;
 238         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 239         if (!ce)
 240                 return error("addinfo_cache failed for path '%s'", path);
 241         return add_cache_entry(ce, options);
 242 }
 243
 244 /*
 245  * This is a global variable which is used in a number of places but
 246  * only written to in the 'merge' function.
 247  *
 248  * index_only == 1    => Don't leave any non-stage 0 entries in the cache and
 249  *                       don't update the working directory.
 250  *               0    => Leave unmerged entries in the cache and update
 251  *                       the working directory.
 252  */
 253 static int index_only = 0;
 254
 255 static int git_merge_trees(int index_only,
 256                            struct tree *common,
 257                            struct tree *head,
 258                            struct tree *merge)
 259 {
 260         int rc;
 261         struct object_list *trees = NULL;
 262         struct unpack_trees_options opts;
 263
 264         memset(&opts, 0, sizeof(opts));
 265         if (index_only)
 266                 opts.index_only = 1;
 267         else
 268                 opts.update = 1;
 269         opts.merge = 1;
 270         opts.head_idx = 2;
 271         opts.fn = threeway_merge;
 272
 273         object_list_append(&common->object, &trees);
 274         object_list_append(&head->object, &trees);
 275         object_list_append(&merge->object, &trees);
 276
 277         rc = unpack_trees(trees, &opts);
 278         cache_tree_free(&active_cache_tree);
 279         return rc;
 280 }
 281
 282 static int unmerged_index(void)
 283 {
 284         int i;
 285         for (i = 0; i < active_nr; i++) {
 286                 struct cache_entry *ce = active_cache[i];
 287                 if (ce_stage(ce))
 288                         return 1;
 289         }
 290         return 0;
 291 }
 292
 293 static struct tree *git_write_tree(void)
 294 {
 295         struct tree *result = NULL;
 296
 297         if (unmerged_index()) {
 298                 int i;
 299                 output(0, "There are unmerged index entries:");
 300                 for (i = 0; i < active_nr; i++) {
 301                         struct cache_entry *ce = active_cache[i];
 302                         if (ce_stage(ce))
 303                                 output(0, "%d %.*s", ce_stage(ce), ce_namelen(ce), ce->name);
 304                 }
 305                 return NULL;
 306         }
 307
 308         if (!active_cache_tree)
 309                 active_cache_tree = cache_tree();
 310
 311         if (!cache_tree_fully_valid(active_cache_tree) &&
 312             cache_tree_update(active_cache_tree,
 313                               active_cache, active_nr, 0, 0) < 0)
 314                 die("error building trees");
 315
 316         result = lookup_tree(active_cache_tree->sha1);
 317
 318         return result;
 319 }
 320
 321 static int save_files_dirs(const unsigned char *sha1,
 322                 const char *base, int baselen, const char *path,
 323                 unsigned int mode, int stage)
 324 {
 325         int len = strlen(path);
 326         char *newpath = xmalloc(baselen + len + 1);
 327         memcpy(newpath, base, baselen);
 328         memcpy(newpath + baselen, path, len);
 329         newpath[baselen + len] = '\0';
 330
 331         if (S_ISDIR(mode))
 332                 path_list_insert(newpath, &current_directory_set);
 333         else
 334                 path_list_insert(newpath, &current_file_set);
 335         free(newpath);
 336
 337         return READ_TREE_RECURSIVE;
 338 }
 339
 340 static int get_files_dirs(struct tree *tree)
 341 {
 342         int n;
 343         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs) != 0)
 344                 return 0;
 345         n = current_file_set.nr + current_directory_set.nr;
 346         return n;
 347 }
 348
 349 /*
 350  * Returns a index_entry instance which doesn't have to correspond to
 351  * a real cache entry in Git's index.
 352  */
 353 static struct stage_data *insert_stage_data(const char *path,
 354                 struct tree *o, struct tree *a, struct tree *b,
 355                 struct path_list *entries)
 356 {
 357         struct path_list_item *item;
 358         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 359         get_tree_entry(o->object.sha1, path,
 360                         e->stages[1].sha, &e->stages[1].mode);
 361         get_tree_entry(a->object.sha1, path,
 362                         e->stages[2].sha, &e->stages[2].mode);
 363         get_tree_entry(b->object.sha1, path,
 364                         e->stages[3].sha, &e->stages[3].mode);
 365         item = path_list_insert(path, entries);
 366         item->util = e;
 367         return e;
 368 }
 369
 370 /*
 371  * Create a dictionary mapping file names to stage_data objects. The
 372  * dictionary contains one entry for every path with a non-zero stage entry.
 373  */
 374 static struct path_list *get_unmerged(void)
 375 {
 376         struct path_list *unmerged = xcalloc(1, sizeof(struct path_list));
 377         int i;
 378
 379         unmerged->strdup_paths = 1;
 380         total_cnt += active_nr;
 381
 382         for (i = 0; i < active_nr; i++, merged_cnt++) {
 383                 struct path_list_item *item;
 384                 struct stage_data *e;
 385                 struct cache_entry *ce = active_cache[i];
 386                 if (do_progress)
 387                         display_progress();
 388                 if (!ce_stage(ce))
 389                         continue;
 390
 391                 item = path_list_lookup(ce->name, unmerged);
 392                 if (!item) {
 393                         item = path_list_insert(ce->name, unmerged);
 394                         item->util = xcalloc(1, sizeof(struct stage_data));
 395                 }
 396                 e = item->util;
 397                 e->stages[ce_stage(ce)].mode = ntohl(ce->ce_mode);
 398                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 399         }
 400
 401         return unmerged;
 402 }
 403
 404 struct rename
 405 {
 406         struct diff_filepair *pair;
 407         struct stage_data *src_entry;
 408         struct stage_data *dst_entry;
 409         unsigned processed:1;
 410 };
 411
 412 /*
 413  * Get information of all renames which occurred between 'o_tree' and
 414  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 415  * 'b_tree') to be able to associate the correct cache entries with
 416  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 417  */
 418 static struct path_list *get_renames(struct tree *tree,
 419                                         struct tree *o_tree,
 420                                         struct tree *a_tree,
 421                                         struct tree *b_tree,
 422                                         struct path_list *entries)
 423 {
 424         int i;
 425         struct path_list *renames;
 426         struct diff_options opts;
 427
 428         renames = xcalloc(1, sizeof(struct path_list));
 429         diff_setup(&opts);
 430         opts.recursive = 1;
 431         opts.detect_rename = DIFF_DETECT_RENAME;
 432         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 433         if (diff_setup_done(&opts) < 0)
 434                 die("diff setup failed");
 435         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 436         diffcore_std(&opts);
 437         for (i = 0; i < diff_queued_diff.nr; ++i) {
 438                 struct path_list_item *item;
 439                 struct rename *re;
 440                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 441                 if (pair->status != 'R') {
 442                         diff_free_filepair(pair);
 443                         continue;
 444                 }
 445                 re = xmalloc(sizeof(*re));
 446                 re->processed = 0;
 447                 re->pair = pair;
 448                 item = path_list_lookup(re->pair->one->path, entries);
 449                 if (!item)
 450                         re->src_entry = insert_stage_data(re->pair->one->path,
 451                                         o_tree, a_tree, b_tree, entries);
 452                 else
 453                         re->src_entry = item->util;
 454
 455                 item = path_list_lookup(re->pair->two->path, entries);
 456                 if (!item)
 457                         re->dst_entry = insert_stage_data(re->pair->two->path,
 458                                         o_tree, a_tree, b_tree, entries);
 459                 else
 460                         re->dst_entry = item->util;
 461                 item = path_list_insert(pair->one->path, renames);
 462                 item->util = re;
 463         }
 464         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 465         diff_queued_diff.nr = 0;
 466         diff_flush(&opts);
 467         return renames;
 468 }
 469
 470 static int update_stages(const char *path, struct diff_filespec *o,
 471                          struct diff_filespec *a, struct diff_filespec *b,
 472                          int clear)
 473 {
 474         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 475         if (clear)
 476                 if (remove_file_from_cache(path))
 477                         return -1;
 478         if (o)
 479                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 480                         return -1;
 481         if (a)
 482                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 483                         return -1;
 484         if (b)
 485                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 486                         return -1;
 487         return 0;
 488 }
 489
 490 static int remove_path(const char *name)
 491 {
 492         int ret, len;
 493         char *slash, *dirs;
 494
 495         ret = unlink(name);
 496         if (ret)
 497                 return ret;
 498         len = strlen(name);
 499         dirs = xmalloc(len+1);
 500         memcpy(dirs, name, len);
 501         dirs[len] = '\0';
 502         while ((slash = strrchr(name, '/'))) {
 503                 *slash = '\0';
 504                 len = slash - name;
 505                 if (rmdir(name) != 0)
 506                         break;
 507         }
 508         free(dirs);
 509         return ret;
 510 }
 511
 512 static int remove_file(int clean, const char *path, int no_wd)
 513 {
 514         int update_cache = index_only || clean;
 515         int update_working_directory = !index_only && !no_wd;
 516
 517         if (update_cache) {
 518                 if (remove_file_from_cache(path))
 519                         return -1;
 520         }
 521         if (update_working_directory) {
 522                 unlink(path);
 523                 if (errno != ENOENT || errno != EISDIR)
 524                         return -1;
 525                 remove_path(path);
 526         }
 527         return 0;
 528 }
 529
 530 static char *unique_path(const char *path, const char *branch)
 531 {
 532         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 533         int suffix = 0;
 534         struct stat st;
 535         char *p = newpath + strlen(path);
 536         strcpy(newpath, path);
 537         *(p++) = '~';
 538         strcpy(p, branch);
 539         for (; *p; ++p)
 540                 if ('/' == *p)
 541                         *p = '_';
 542         while (path_list_has_path(&current_file_set, newpath) ||
 543                path_list_has_path(&current_directory_set, newpath) ||
 544                lstat(newpath, &st) == 0)
 545                 sprintf(p, "_%d", suffix++);
 546
 547         path_list_insert(newpath, &current_file_set);
 548         return newpath;
 549 }
 550
 551 static int mkdir_p(const char *path, unsigned long mode)
 552 {
 553         /* path points to cache entries, so xstrdup before messing with it */
 554         char *buf = xstrdup(path);
 555         int result = safe_create_leading_directories(buf);
 556         free(buf);
 557         return result;
 558 }
 559
 560 static void flush_buffer(int fd, const char *buf, unsigned long size)
 561 {
 562         while (size > 0) {
 563                 long ret = write_in_full(fd, buf, size);
 564                 if (ret < 0) {
 565                         /* Ignore epipe */
 566                         if (errno == EPIPE)
 567                                 break;
 568                         die("merge-recursive: %s", strerror(errno));
 569                 } else if (!ret) {
 570                         die("merge-recursive: disk full?");
 571                 }
 572                 size -= ret;
 573                 buf += ret;
 574         }
 575 }
 576
 577 static void update_file_flags(const unsigned char *sha,
 578                               unsigned mode,
 579                               const char *path,
 580                               int update_cache,
 581                               int update_wd)
 582 {
 583         if (index_only)
 584                 update_wd = 0;
 585
 586         if (update_wd) {
 587                 enum object_type type;
 588                 void *buf;
 589                 unsigned long size;
 590
 591                 buf = read_sha1_file(sha, &type, &size);
 592                 if (!buf)
 593                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 594                 if (type != OBJ_BLOB)
 595                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 596
 597                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 598                         int fd;
 599                         if (mkdir_p(path, 0777))
 600                                 die("failed to create path %s: %s", path, strerror(errno));
 601                         unlink(path);
 602                         if (mode & 0100)
 603                                 mode = 0777;
 604                         else
 605                                 mode = 0666;
 606                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 607                         if (fd < 0)
 608                                 die("failed to open %s: %s", path, strerror(errno));
 609                         flush_buffer(fd, buf, size);
 610                         close(fd);
 611                 } else if (S_ISLNK(mode)) {
 612                         char *lnk = xmalloc(size + 1);
 613                         memcpy(lnk, buf, size);
 614                         lnk[size] = '\0';
 615                         mkdir_p(path, 0777);
 616                         unlink(path);
 617                         symlink(lnk, path);
 618                         free(lnk);
 619                 } else
 620                         die("do not know what to do with %06o %s '%s'",
 621                             mode, sha1_to_hex(sha), path);
 622         }
 623         if (update_cache)
 624                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 625 }
 626
 627 static void update_file(int clean,
 628                         const unsigned char *sha,
 629                         unsigned mode,
 630                         const char *path)
 631 {
 632         update_file_flags(sha, mode, path, index_only || clean, !index_only);
 633 }
 634
 635 /* Low level file merging, update and removal */
 636
 637 struct merge_file_info
 638 {
 639         unsigned char sha[20];
 640         unsigned mode;
 641         unsigned clean:1,
 642                  merge:1;
 643 };
 644
 645 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 646 {
 647         unsigned long size;
 648         enum object_type type;
 649
 650         if (!hashcmp(sha1, null_sha1)) {
 651                 mm->ptr = xstrdup("");
 652                 mm->size = 0;
 653                 return;
 654         }
 655
 656         mm->ptr = read_sha1_file(sha1, &type, &size);
 657         if (!mm->ptr || type != OBJ_BLOB)
 658                 die("unable to read blob object %s", sha1_to_hex(sha1));
 659         mm->size = size;
 660 }
 661
 662 static int ll_merge(mmbuffer_t *result_buf,
 663                     struct diff_filespec *o,
 664                     struct diff_filespec *a,
 665                     struct diff_filespec *b,
 666                     const char *branch1,
 667                     const char *branch2)
 668 {
 669         mmfile_t orig, src1, src2;
 670         xpparam_t xpp;
 671         char *name1, *name2;
 672         int merge_status;
 673
 674         name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 675         name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 676
 677         fill_mm(o->sha1, &orig);
 678         fill_mm(a->sha1, &src1);
 679         fill_mm(b->sha1, &src2);
 680
 681         memset(&xpp, 0, sizeof(xpp));
 682         merge_status = xdl_merge(&orig,
 683                                  &src1, name1,
 684                                  &src2, name2,
 685                                  &xpp, XDL_MERGE_ZEALOUS,
 686                                  result_buf);
 687         free(name1);
 688         free(name2);
 689         free(orig.ptr);
 690         free(src1.ptr);
 691         free(src2.ptr);
 692         return merge_status;
 693 }
 694
 695 static struct merge_file_info merge_file(struct diff_filespec *o,
 696                 struct diff_filespec *a, struct diff_filespec *b,
 697                 const char *branch1, const char *branch2)
 698 {
 699         struct merge_file_info result;
 700         result.merge = 0;
 701         result.clean = 1;
 702
 703         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 704                 result.clean = 0;
 705                 if (S_ISREG(a->mode)) {
 706                         result.mode = a->mode;
 707                         hashcpy(result.sha, a->sha1);
 708                 } else {
 709                         result.mode = b->mode;
 710                         hashcpy(result.sha, b->sha1);
 711                 }
 712         } else {
 713                 if (!sha_eq(a->sha1, o->sha1) && !sha_eq(b->sha1, o->sha1))
 714                         result.merge = 1;
 715
 716                 result.mode = a->mode == o->mode ? b->mode: a->mode;
 717
 718                 if (sha_eq(a->sha1, o->sha1))
 719                         hashcpy(result.sha, b->sha1);
 720                 else if (sha_eq(b->sha1, o->sha1))
 721                         hashcpy(result.sha, a->sha1);
 722                 else if (S_ISREG(a->mode)) {
 723                         mmbuffer_t result_buf;
 724                         int merge_status;
 725
 726                         merge_status = ll_merge(&result_buf, o, a, b,
 727                                                 branch1, branch2);
 728
 729                         if ((merge_status < 0) || !result_buf.ptr)
 730                                 die("Failed to execute internal merge");
 731
 732                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 733                                             blob_type, result.sha))
 734                                 die("Unable to add %s to database",
 735                                     a->path);
 736
 737                         free(result_buf.ptr);
 738                         result.clean = (merge_status == 0);
 739                 } else {
 740                         if (!(S_ISLNK(a->mode) || S_ISLNK(b->mode)))
 741                                 die("cannot merge modes?");
 742
 743                         hashcpy(result.sha, a->sha1);
 744
 745                         if (!sha_eq(a->sha1, b->sha1))
 746                                 result.clean = 0;
 747                 }
 748         }
 749
 750         return result;
 751 }
 752
 753 static void conflict_rename_rename(struct rename *ren1,
 754                                    const char *branch1,
 755                                    struct rename *ren2,
 756                                    const char *branch2)
 757 {
 758         char *del[2];
 759         int delp = 0;
 760         const char *ren1_dst = ren1->pair->two->path;
 761         const char *ren2_dst = ren2->pair->two->path;
 762         const char *dst_name1 = ren1_dst;
 763         const char *dst_name2 = ren2_dst;
 764         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 765                 dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
 766                 output(1, "%s is a directory in %s added as %s instead",
 767                        ren1_dst, branch2, dst_name1);
 768                 remove_file(0, ren1_dst, 0);
 769         }
 770         if (path_list_has_path(&current_directory_set, ren2_dst)) {
 771                 dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
 772                 output(1, "%s is a directory in %s added as %s instead",
 773                        ren2_dst, branch1, dst_name2);
 774                 remove_file(0, ren2_dst, 0);
 775         }
 776         if (index_only) {
 777                 remove_file_from_cache(dst_name1);
 778                 remove_file_from_cache(dst_name2);
 779                 /*
 780                  * Uncomment to leave the conflicting names in the resulting tree
 781                  *
 782                  * update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
 783                  * update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
 784                  */
 785         } else {
 786                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
 787                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
 788         }
 789         while (delp--)
 790                 free(del[delp]);
 791 }
 792
 793 static void conflict_rename_dir(struct rename *ren1,
 794                                 const char *branch1)
 795 {
 796         char *new_path = unique_path(ren1->pair->two->path, branch1);
 797         output(1, "Renamed %s to %s instead", ren1->pair->one->path, new_path);
 798         remove_file(0, ren1->pair->two->path, 0);
 799         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
 800         free(new_path);
 801 }
 802
 803 static void conflict_rename_rename_2(struct rename *ren1,
 804                                      const char *branch1,
 805                                      struct rename *ren2,
 806                                      const char *branch2)
 807 {
 808         char *new_path1 = unique_path(ren1->pair->two->path, branch1);
 809         char *new_path2 = unique_path(ren2->pair->two->path, branch2);
 810         output(1, "Renamed %s to %s and %s to %s instead",
 811                ren1->pair->one->path, new_path1,
 812                ren2->pair->one->path, new_path2);
 813         remove_file(0, ren1->pair->two->path, 0);
 814         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 815         update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 816         free(new_path2);
 817         free(new_path1);
 818 }
 819
 820 static int process_renames(struct path_list *a_renames,
 821                            struct path_list *b_renames,
 822                            const char *a_branch,
 823                            const char *b_branch)
 824 {
 825         int clean_merge = 1, i, j;
 826         struct path_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
 827         const struct rename *sre;
 828
 829         for (i = 0; i < a_renames->nr; i++) {
 830                 sre = a_renames->items[i].util;
 831                 path_list_insert(sre->pair->two->path, &a_by_dst)->util
 832                         = sre->dst_entry;
 833         }
 834         for (i = 0; i < b_renames->nr; i++) {
 835                 sre = b_renames->items[i].util;
 836                 path_list_insert(sre->pair->two->path, &b_by_dst)->util
 837                         = sre->dst_entry;
 838         }
 839
 840         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 841                 int compare;
 842                 char *src;
 843                 struct path_list *renames1, *renames2, *renames2Dst;
 844                 struct rename *ren1 = NULL, *ren2 = NULL;
 845                 const char *branch1, *branch2;
 846                 const char *ren1_src, *ren1_dst;
 847
 848                 if (i >= a_renames->nr) {
 849                         compare = 1;
 850                         ren2 = b_renames->items[j++].util;
 851                 } else if (j >= b_renames->nr) {
 852                         compare = -1;
 853                         ren1 = a_renames->items[i++].util;
 854                 } else {
 855                         compare = strcmp(a_renames->items[i].path,
 856                                         b_renames->items[j].path);
 857                         if (compare <= 0)
 858                                 ren1 = a_renames->items[i++].util;
 859                         if (compare >= 0)
 860                                 ren2 = b_renames->items[j++].util;
 861                 }
 862
 863                 /* TODO: refactor, so that 1/2 are not needed */
 864                 if (ren1) {
 865                         renames1 = a_renames;
 866                         renames2 = b_renames;
 867                         renames2Dst = &b_by_dst;
 868                         branch1 = a_branch;
 869                         branch2 = b_branch;
 870                 } else {
 871                         struct rename *tmp;
 872                         renames1 = b_renames;
 873                         renames2 = a_renames;
 874                         renames2Dst = &a_by_dst;
 875                         branch1 = b_branch;
 876                         branch2 = a_branch;
 877                         tmp = ren2;
 878                         ren2 = ren1;
 879                         ren1 = tmp;
 880                 }
 881                 src = ren1->pair->one->path;
 882
 883                 ren1->dst_entry->processed = 1;
 884                 ren1->src_entry->processed = 1;
 885
 886                 if (ren1->processed)
 887                         continue;
 888                 ren1->processed = 1;
 889
 890                 ren1_src = ren1->pair->one->path;
 891                 ren1_dst = ren1->pair->two->path;
 892
 893                 if (ren2) {
 894                         const char *ren2_src = ren2->pair->one->path;
 895                         const char *ren2_dst = ren2->pair->two->path;
 896                         /* Renamed in 1 and renamed in 2 */
 897                         if (strcmp(ren1_src, ren2_src) != 0)
 898                                 die("ren1.src != ren2.src");
 899                         ren2->dst_entry->processed = 1;
 900                         ren2->processed = 1;
 901                         if (strcmp(ren1_dst, ren2_dst) != 0) {
 902                                 clean_merge = 0;
 903                                 output(1, "CONFLICT (rename/rename): "
 904                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
 905                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
 906                                        src, ren1_dst, branch1,
 907                                        src, ren2_dst, branch2,
 908                                        index_only ? " (left unresolved)": "");
 909                                 if (index_only) {
 910                                         remove_file_from_cache(src);
 911                                         update_file(0, ren1->pair->one->sha1,
 912                                                     ren1->pair->one->mode, src);
 913                                 }
 914                                 conflict_rename_rename(ren1, branch1, ren2, branch2);
 915                         } else {
 916                                 struct merge_file_info mfi;
 917                                 remove_file(1, ren1_src, 1);
 918                                 mfi = merge_file(ren1->pair->one,
 919                                                  ren1->pair->two,
 920                                                  ren2->pair->two,
 921                                                  branch1,
 922                                                  branch2);
 923                                 if (mfi.merge || !mfi.clean)
 924                                         output(1, "Renamed %s->%s", src, ren1_dst);
 925
 926                                 if (mfi.merge)
 927                                         output(2, "Auto-merged %s", ren1_dst);
 928
 929                                 if (!mfi.clean) {
 930                                         output(1, "CONFLICT (content): merge conflict in %s",
 931                                                ren1_dst);
 932                                         clean_merge = 0;
 933
 934                                         if (!index_only)
 935                                                 update_stages(ren1_dst,
 936                                                               ren1->pair->one,
 937                                                               ren1->pair->two,
 938                                                               ren2->pair->two,
 939                                                               1 /* clear */);
 940                                 }
 941                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 942                         }
 943                 } else {
 944                         /* Renamed in 1, maybe changed in 2 */
 945                         struct path_list_item *item;
 946                         /* we only use sha1 and mode of these */
 947                         struct diff_filespec src_other, dst_other;
 948                         int try_merge, stage = a_renames == renames1 ? 3: 2;
 949
 950                         remove_file(1, ren1_src, index_only || stage == 3);
 951
 952                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
 953                         src_other.mode = ren1->src_entry->stages[stage].mode;
 954                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
 955                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
 956
 957                         try_merge = 0;
 958
 959                         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 960                                 clean_merge = 0;
 961                                 output(1, "CONFLICT (rename/directory): Renamed %s->%s in %s "
 962                                        " directory %s added in %s",
 963                                        ren1_src, ren1_dst, branch1,
 964                                        ren1_dst, branch2);
 965                                 conflict_rename_dir(ren1, branch1);
 966                         } else if (sha_eq(src_other.sha1, null_sha1)) {
 967                                 clean_merge = 0;
 968                                 output(1, "CONFLICT (rename/delete): Renamed %s->%s in %s "
 969                                        "and deleted in %s",
 970                                        ren1_src, ren1_dst, branch1,
 971                                        branch2);
 972                                 update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
 973                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
 974                                 const char *new_path;
 975                                 clean_merge = 0;
 976                                 try_merge = 1;
 977                                 output(1, "CONFLICT (rename/add): Renamed %s->%s in %s. "
 978                                        "%s added in %s",
 979                                        ren1_src, ren1_dst, branch1,
 980                                        ren1_dst, branch2);
 981                                 new_path = unique_path(ren1_dst, branch2);
 982                                 output(1, "Added as %s instead", new_path);
 983                                 update_file(0, dst_other.sha1, dst_other.mode, new_path);
 984                         } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
 985                                 ren2 = item->util;
 986                                 clean_merge = 0;
 987                                 ren2->processed = 1;
 988                                 output(1, "CONFLICT (rename/rename): Renamed %s->%s in %s. "
 989                                        "Renamed %s->%s in %s",
 990                                        ren1_src, ren1_dst, branch1,
 991                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
 992                                 conflict_rename_rename_2(ren1, branch1, ren2, branch2);
 993                         } else
 994                                 try_merge = 1;
 995
 996                         if (try_merge) {
 997                                 struct diff_filespec *o, *a, *b;
 998                                 struct merge_file_info mfi;
 999                                 src_other.path = (char *)ren1_src;
1000
1001                                 o = ren1->pair->one;
1002                                 if (a_renames == renames1) {
1003                                         a = ren1->pair->two;
1004                                         b = &src_other;
1005                                 } else {
1006                                         b = ren1->pair->two;
1007                                         a = &src_other;
1008                                 }
1009                                 mfi = merge_file(o, a, b,
1010                                                 a_branch, b_branch);
1011
1012                                 if (mfi.merge || !mfi.clean)
1013                                         output(1, "Renamed %s => %s", ren1_src, ren1_dst);
1014                                 if (mfi.merge)
1015                                         output(2, "Auto-merged %s", ren1_dst);
1016                                 if (!mfi.clean) {
1017                                         output(1, "CONFLICT (rename/modify): Merge conflict in %s",
1018                                                ren1_dst);
1019                                         clean_merge = 0;
1020
1021                                         if (!index_only)
1022                                                 update_stages(ren1_dst,
1023                                                                 o, a, b, 1);
1024                                 }
1025                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1026                         }
1027                 }
1028         }
1029         path_list_clear(&a_by_dst, 0);
1030         path_list_clear(&b_by_dst, 0);
1031
1032         return clean_merge;
1033 }
1034
1035 static unsigned char *has_sha(const unsigned char *sha)
1036 {
1037         return is_null_sha1(sha) ? NULL: (unsigned char *)sha;
1038 }
1039
1040 /* Per entry merge function */
1041 static int process_entry(const char *path, struct stage_data *entry,
1042                          const char *branch1,
1043                          const char *branch2)
1044 {
1045         /*
1046         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1047         print_index_entry("\tpath: ", entry);
1048         */
1049         int clean_merge = 1;
1050         unsigned char *o_sha = has_sha(entry->stages[1].sha);
1051         unsigned char *a_sha = has_sha(entry->stages[2].sha);
1052         unsigned char *b_sha = has_sha(entry->stages[3].sha);
1053         unsigned o_mode = entry->stages[1].mode;
1054         unsigned a_mode = entry->stages[2].mode;
1055         unsigned b_mode = entry->stages[3].mode;
1056
1057         if (o_sha && (!a_sha || !b_sha)) {
1058                 /* Case A: Deleted in one */
1059                 if ((!a_sha && !b_sha) ||
1060                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1061                     (!a_sha && sha_eq(b_sha, o_sha))) {
1062                         /* Deleted in both or deleted in one and
1063                          * unchanged in the other */
1064                         if (a_sha)
1065                                 output(2, "Removed %s", path);
1066                         /* do not touch working file if it did not exist */
1067                         remove_file(1, path, !a_sha);
1068                 } else {
1069                         /* Deleted in one and changed in the other */
1070                         clean_merge = 0;
1071                         if (!a_sha) {
1072                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1073                                        "and modified in %s. Version %s of %s left in tree.",
1074                                        path, branch1,
1075                                        branch2, branch2, path);
1076                                 update_file(0, b_sha, b_mode, path);
1077                         } else {
1078                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1079                                        "and modified in %s. Version %s of %s left in tree.",
1080                                        path, branch2,
1081                                        branch1, branch1, path);
1082                                 update_file(0, a_sha, a_mode, path);
1083                         }
1084                 }
1085
1086         } else if ((!o_sha && a_sha && !b_sha) ||
1087                    (!o_sha && !a_sha && b_sha)) {
1088                 /* Case B: Added in one. */
1089                 const char *add_branch;
1090                 const char *other_branch;
1091                 unsigned mode;
1092                 const unsigned char *sha;
1093                 const char *conf;
1094
1095                 if (a_sha) {
1096                         add_branch = branch1;
1097                         other_branch = branch2;
1098                         mode = a_mode;
1099                         sha = a_sha;
1100                         conf = "file/directory";
1101                 } else {
1102                         add_branch = branch2;
1103                         other_branch = branch1;
1104                         mode = b_mode;
1105                         sha = b_sha;
1106                         conf = "directory/file";
1107                 }
1108                 if (path_list_has_path(&current_directory_set, path)) {
1109                         const char *new_path = unique_path(path, add_branch);
1110                         clean_merge = 0;
1111                         output(1, "CONFLICT (%s): There is a directory with name %s in %s. "
1112                                "Added %s as %s",
1113                                conf, path, other_branch, path, new_path);
1114                         remove_file(0, path, 0);
1115                         update_file(0, sha, mode, new_path);
1116                 } else {
1117                         output(2, "Added %s", path);
1118                         update_file(1, sha, mode, path);
1119                 }
1120         } else if (a_sha && b_sha) {
1121                 /* Case C: Added in both (check for same permissions) and */
1122                 /* case D: Modified in both, but differently. */
1123                 const char *reason = "content";
1124                 struct merge_file_info mfi;
1125                 struct diff_filespec o, a, b;
1126
1127                 if (!o_sha) {
1128                         reason = "add/add";
1129                         o_sha = (unsigned char *)null_sha1;
1130                 }
1131                 output(2, "Auto-merged %s", path);
1132                 o.path = a.path = b.path = (char *)path;
1133                 hashcpy(o.sha1, o_sha);
1134                 o.mode = o_mode;
1135                 hashcpy(a.sha1, a_sha);
1136                 a.mode = a_mode;
1137                 hashcpy(b.sha1, b_sha);
1138                 b.mode = b_mode;
1139
1140                 mfi = merge_file(&o, &a, &b,
1141                                  branch1, branch2);
1142
1143                 if (mfi.clean)
1144                         update_file(1, mfi.sha, mfi.mode, path);
1145                 else {
1146                         clean_merge = 0;
1147                         output(1, "CONFLICT (%s): Merge conflict in %s",
1148                                         reason, path);
1149
1150                         if (index_only)
1151                                 update_file(0, mfi.sha, mfi.mode, path);
1152                         else
1153                                 update_file_flags(mfi.sha, mfi.mode, path,
1154                                               0 /* update_cache */, 1 /* update_working_directory */);
1155                 }
1156         } else
1157                 die("Fatal merge failure, shouldn't happen.");
1158
1159         return clean_merge;
1160 }
1161
1162 static int merge_trees(struct tree *head,
1163                        struct tree *merge,
1164                        struct tree *common,
1165                        const char *branch1,
1166                        const char *branch2,
1167                        struct tree **result)
1168 {
1169         int code, clean;
1170
1171         if (subtree_merge) {
1172                 merge = shift_tree_object(head, merge);
1173                 common = shift_tree_object(head, common);
1174         }
1175
1176         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1177                 output(0, "Already uptodate!");
1178                 *result = head;
1179                 return 1;
1180         }
1181
1182         code = git_merge_trees(index_only, common, head, merge);
1183
1184         if (code != 0)
1185                 die("merging of trees %s and %s failed",
1186                     sha1_to_hex(head->object.sha1),
1187                     sha1_to_hex(merge->object.sha1));
1188
1189         if (unmerged_index()) {
1190                 struct path_list *entries, *re_head, *re_merge;
1191                 int i;
1192                 path_list_clear(&current_file_set, 1);
1193                 path_list_clear(&current_directory_set, 1);
1194                 get_files_dirs(head);
1195                 get_files_dirs(merge);
1196
1197                 entries = get_unmerged();
1198                 re_head  = get_renames(head, common, head, merge, entries);
1199                 re_merge = get_renames(merge, common, head, merge, entries);
1200                 clean = process_renames(re_head, re_merge,
1201                                 branch1, branch2);
1202                 total_cnt += entries->nr;
1203                 for (i = 0; i < entries->nr; i++, merged_cnt++) {
1204                         const char *path = entries->items[i].path;
1205                         struct stage_data *e = entries->items[i].util;
1206                         if (!e->processed
1207                                 && !process_entry(path, e, branch1, branch2))
1208                                 clean = 0;
1209                         if (do_progress)
1210                                 display_progress();
1211                 }
1212
1213                 path_list_clear(re_merge, 0);
1214                 path_list_clear(re_head, 0);
1215                 path_list_clear(entries, 1);
1216
1217         }
1218         else
1219                 clean = 1;
1220
1221         if (index_only)
1222                 *result = git_write_tree();
1223
1224         return clean;
1225 }
1226
1227 static struct commit_list *reverse_commit_list(struct commit_list *list)
1228 {
1229         struct commit_list *next = NULL, *current, *backup;
1230         for (current = list; current; current = backup) {
1231                 backup = current->next;
1232                 current->next = next;
1233                 next = current;
1234         }
1235         return next;
1236 }
1237
1238 /*
1239  * Merge the commits h1 and h2, return the resulting virtual
1240  * commit object and a flag indicating the cleanness of the merge.
1241  */
1242 static int merge(struct commit *h1,
1243                  struct commit *h2,
1244                  const char *branch1,
1245                  const char *branch2,
1246                  struct commit_list *ca,
1247                  struct commit **result)
1248 {
1249         struct commit_list *iter;
1250         struct commit *merged_common_ancestors;
1251         struct tree *mrtree;
1252         int clean;
1253
1254         if (show(4)) {
1255                 output(4, "Merging:");
1256                 output_commit_title(h1);
1257                 output_commit_title(h2);
1258         }
1259
1260         if (!ca) {
1261                 ca = get_merge_bases(h1, h2, 1);
1262                 ca = reverse_commit_list(ca);
1263         }
1264
1265         if (show(5)) {
1266                 output(5, "found %u common ancestor(s):", commit_list_count(ca));
1267                 for (iter = ca; iter; iter = iter->next)
1268                         output_commit_title(iter->item);
1269         }
1270
1271         merged_common_ancestors = pop_commit(&ca);
1272         if (merged_common_ancestors == NULL) {
1273                 /* if there is no common ancestor, make an empty tree */
1274                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1275
1276                 tree->object.parsed = 1;
1277                 tree->object.type = OBJ_TREE;
1278                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1279                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1280         }
1281
1282         for (iter = ca; iter; iter = iter->next) {
1283                 call_depth++;
1284                 /*
1285                  * When the merge fails, the result contains files
1286                  * with conflict markers. The cleanness flag is
1287                  * ignored, it was never actually used, as result of
1288                  * merge_trees has always overwritten it: the committed
1289                  * "conflicts" were already resolved.
1290                  */
1291                 discard_cache();
1292                 merge(merged_common_ancestors, iter->item,
1293                       "Temporary merge branch 1",
1294                       "Temporary merge branch 2",
1295                       NULL,
1296                       &merged_common_ancestors);
1297                 call_depth--;
1298
1299                 if (!merged_common_ancestors)
1300                         die("merge returned no commit");
1301         }
1302
1303         discard_cache();
1304         if (!call_depth) {
1305                 read_cache();
1306                 index_only = 0;
1307         } else
1308                 index_only = 1;
1309
1310         clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
1311                             branch1, branch2, &mrtree);
1312
1313         if (index_only) {
1314                 *result = make_virtual_commit(mrtree, "merged tree");
1315                 commit_list_insert(h1, &(*result)->parents);
1316                 commit_list_insert(h2, &(*result)->parents->next);
1317         }
1318         if (!call_depth && do_progress) {
1319                 /* Make sure we end at 100% */
1320                 if (!total_cnt)
1321                         total_cnt = 1;
1322                 merged_cnt = total_cnt;
1323                 progress_update = 1;
1324                 display_progress();
1325                 fputc('\n', stderr);
1326         }
1327         flush_output();
1328         return clean;
1329 }
1330
1331 static const char *better_branch_name(const char *branch)
1332 {
1333         static char githead_env[8 + 40 + 1];
1334         char *name;
1335
1336         if (strlen(branch) != 40)
1337                 return branch;
1338         sprintf(githead_env, "GITHEAD_%s", branch);
1339         name = getenv(githead_env);
1340         return name ? name : branch;
1341 }
1342
1343 static struct commit *get_ref(const char *ref)
1344 {
1345         unsigned char sha1[20];
1346         struct object *object;
1347
1348         if (get_sha1(ref, sha1))
1349                 die("Could not resolve ref '%s'", ref);
1350         object = deref_tag(parse_object(sha1), ref, strlen(ref));
1351         if (object->type == OBJ_TREE)
1352                 return make_virtual_commit((struct tree*)object,
1353                         better_branch_name(ref));
1354         if (object->type != OBJ_COMMIT)
1355                 return NULL;
1356         if (parse_commit((struct commit *)object))
1357                 die("Could not parse commit '%s'", sha1_to_hex(object->sha1));
1358         return (struct commit *)object;
1359 }
1360
1361 static int merge_config(const char *var, const char *value)
1362 {
1363         if (!strcasecmp(var, "merge.verbosity")) {
1364                 verbosity = git_config_int(var, value);
1365                 return 0;
1366         }
1367         return git_default_config(var, value);
1368 }
1369
1370 int main(int argc, char *argv[])
1371 {
1372         static const char *bases[20];
1373         static unsigned bases_count = 0;
1374         int i, clean;
1375         const char *branch1, *branch2;
1376         struct commit *result, *h1, *h2;
1377         struct commit_list *ca = NULL;
1378         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1379         int index_fd;
1380
1381         if (argv[0]) {
1382                 int namelen = strlen(argv[0]);
1383                 if (8 < namelen &&
1384                     !strcmp(argv[0] + namelen - 8, "-subtree"))
1385                         subtree_merge = 1;
1386         }
1387
1388         git_config(merge_config);
1389         if (getenv("GIT_MERGE_VERBOSITY"))
1390                 verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1391
1392         if (argc < 4)
1393                 die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
1394
1395         for (i = 1; i < argc; ++i) {
1396                 if (!strcmp(argv[i], "--"))
1397                         break;
1398                 if (bases_count < sizeof(bases)/sizeof(*bases))
1399                         bases[bases_count++] = argv[i];
1400         }
1401         if (argc - i != 3) /* "--" "<head>" "<remote>" */
1402                 die("Not handling anything other than two heads merge.");
1403         if (verbosity >= 5) {
1404                 buffer_output = 0;
1405                 do_progress = 0;
1406         }
1407         else
1408                 do_progress = isatty(1);
1409
1410         branch1 = argv[++i];
1411         branch2 = argv[++i];
1412
1413         h1 = get_ref(branch1);
1414         h2 = get_ref(branch2);
1415
1416         branch1 = better_branch_name(branch1);
1417         branch2 = better_branch_name(branch2);
1418
1419         if (do_progress)
1420                 setup_progress_signal();
1421         if (show(3))
1422                 printf("Merging %s with %s\n", branch1, branch2);
1423
1424         index_fd = hold_locked_index(lock, 1);
1425
1426         for (i = 0; i < bases_count; i++) {
1427                 struct commit *ancestor = get_ref(bases[i]);
1428                 ca = commit_list_insert(ancestor, &ca);
1429         }
1430         clean = merge(h1, h2, branch1, branch2, ca, &result);
1431
1432         if (active_cache_changed &&
1433             (write_cache(index_fd, active_cache, active_nr) ||
1434              close(index_fd) || commit_locked_index(lock)))
1435                         die ("unable to write %s", get_index_file());
1436
1437         return clean ? 0: 1;
1438 }