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 int make_room_for_path(const char *path)
 578 {
 579         int status;
 580         const char *msg = "failed to create path '%s'%s";
 581
 582         status = mkdir_p(path, 0777);
 583         if (status) {
 584                 if (status == -3) {
 585                         /* something else exists */
 586                         error(msg, path, ": perhaps a D/F conflict?");
 587                         return -1;
 588                 }
 589                 die(msg, path, "");
 590         }
 591
 592         /* Successful unlink is good.. */
 593         if (!unlink(path))
 594                 return 0;
 595         /* .. and so is no existing file */
 596         if (errno == ENOENT)
 597                 return 0;
 598         /* .. but not some other error (who really cares what?) */
 599         return error(msg, path, ": perhaps a D/F conflict?");
 600 }
 601
 602 static void update_file_flags(const unsigned char *sha,
 603                               unsigned mode,
 604                               const char *path,
 605                               int update_cache,
 606                               int update_wd)
 607 {
 608         if (index_only)
 609                 update_wd = 0;
 610
 611         if (update_wd) {
 612                 enum object_type type;
 613                 void *buf;
 614                 unsigned long size;
 615
 616                 buf = read_sha1_file(sha, &type, &size);
 617                 if (!buf)
 618                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 619                 if (type != OBJ_BLOB)
 620                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 621
 622                 if (make_room_for_path(path) < 0) {
 623                         update_wd = 0;
 624                         goto update_index;
 625                 }
 626                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 627                         int fd;
 628                         if (mode & 0100)
 629                                 mode = 0777;
 630                         else
 631                                 mode = 0666;
 632                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 633                         if (fd < 0)
 634                                 die("failed to open %s: %s", path, strerror(errno));
 635                         flush_buffer(fd, buf, size);
 636                         close(fd);
 637                 } else if (S_ISLNK(mode)) {
 638                         char *lnk = xmalloc(size + 1);
 639                         memcpy(lnk, buf, size);
 640                         lnk[size] = '\0';
 641                         mkdir_p(path, 0777);
 642                         unlink(path);
 643                         symlink(lnk, path);
 644                         free(lnk);
 645                 } else
 646                         die("do not know what to do with %06o %s '%s'",
 647                             mode, sha1_to_hex(sha), path);
 648         }
 649  update_index:
 650         if (update_cache)
 651                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 652 }
 653
 654 static void update_file(int clean,
 655                         const unsigned char *sha,
 656                         unsigned mode,
 657                         const char *path)
 658 {
 659         update_file_flags(sha, mode, path, index_only || clean, !index_only);
 660 }
 661
 662 /* Low level file merging, update and removal */
 663
 664 struct merge_file_info
 665 {
 666         unsigned char sha[20];
 667         unsigned mode;
 668         unsigned clean:1,
 669                  merge:1;
 670 };
 671
 672 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 673 {
 674         unsigned long size;
 675         enum object_type type;
 676
 677         if (!hashcmp(sha1, null_sha1)) {
 678                 mm->ptr = xstrdup("");
 679                 mm->size = 0;
 680                 return;
 681         }
 682
 683         mm->ptr = read_sha1_file(sha1, &type, &size);
 684         if (!mm->ptr || type != OBJ_BLOB)
 685                 die("unable to read blob object %s", sha1_to_hex(sha1));
 686         mm->size = size;
 687 }
 688
 689 static struct merge_file_info merge_file(struct diff_filespec *o,
 690                 struct diff_filespec *a, struct diff_filespec *b,
 691                 const char *branch1, const char *branch2)
 692 {
 693         struct merge_file_info result;
 694         result.merge = 0;
 695         result.clean = 1;
 696
 697         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 698                 result.clean = 0;
 699                 if (S_ISREG(a->mode)) {
 700                         result.mode = a->mode;
 701                         hashcpy(result.sha, a->sha1);
 702                 } else {
 703                         result.mode = b->mode;
 704                         hashcpy(result.sha, b->sha1);
 705                 }
 706         } else {
 707                 if (!sha_eq(a->sha1, o->sha1) && !sha_eq(b->sha1, o->sha1))
 708                         result.merge = 1;
 709
 710                 result.mode = a->mode == o->mode ? b->mode: a->mode;
 711
 712                 if (sha_eq(a->sha1, o->sha1))
 713                         hashcpy(result.sha, b->sha1);
 714                 else if (sha_eq(b->sha1, o->sha1))
 715                         hashcpy(result.sha, a->sha1);
 716                 else if (S_ISREG(a->mode)) {
 717                         mmfile_t orig, src1, src2;
 718                         mmbuffer_t result_buf;
 719                         xpparam_t xpp;
 720                         char *name1, *name2;
 721                         int merge_status;
 722
 723                         name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 724                         name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 725
 726                         fill_mm(o->sha1, &orig);
 727                         fill_mm(a->sha1, &src1);
 728                         fill_mm(b->sha1, &src2);
 729
 730                         memset(&xpp, 0, sizeof(xpp));
 731                         merge_status = xdl_merge(&orig,
 732                                                  &src1, name1,
 733                                                  &src2, name2,
 734                                                  &xpp, XDL_MERGE_ZEALOUS,
 735                                                  &result_buf);
 736                         free(name1);
 737                         free(name2);
 738                         free(orig.ptr);
 739                         free(src1.ptr);
 740                         free(src2.ptr);
 741
 742                         if ((merge_status < 0) || !result_buf.ptr)
 743                                 die("Failed to execute internal merge");
 744
 745                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 746                                             blob_type, result.sha))
 747                                 die("Unable to add %s to database",
 748                                     a->path);
 749
 750                         free(result_buf.ptr);
 751                         result.clean = (merge_status == 0);
 752                 } else {
 753                         if (!(S_ISLNK(a->mode) || S_ISLNK(b->mode)))
 754                                 die("cannot merge modes?");
 755
 756                         hashcpy(result.sha, a->sha1);
 757
 758                         if (!sha_eq(a->sha1, b->sha1))
 759                                 result.clean = 0;
 760                 }
 761         }
 762
 763         return result;
 764 }
 765
 766 static void conflict_rename_rename(struct rename *ren1,
 767                                    const char *branch1,
 768                                    struct rename *ren2,
 769                                    const char *branch2)
 770 {
 771         char *del[2];
 772         int delp = 0;
 773         const char *ren1_dst = ren1->pair->two->path;
 774         const char *ren2_dst = ren2->pair->two->path;
 775         const char *dst_name1 = ren1_dst;
 776         const char *dst_name2 = ren2_dst;
 777         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 778                 dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
 779                 output(1, "%s is a directory in %s added as %s instead",
 780                        ren1_dst, branch2, dst_name1);
 781                 remove_file(0, ren1_dst, 0);
 782         }
 783         if (path_list_has_path(&current_directory_set, ren2_dst)) {
 784                 dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
 785                 output(1, "%s is a directory in %s added as %s instead",
 786                        ren2_dst, branch1, dst_name2);
 787                 remove_file(0, ren2_dst, 0);
 788         }
 789         if (index_only) {
 790                 remove_file_from_cache(dst_name1);
 791                 remove_file_from_cache(dst_name2);
 792                 /*
 793                  * Uncomment to leave the conflicting names in the resulting tree
 794                  *
 795                  * update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
 796                  * update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
 797                  */
 798         } else {
 799                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
 800                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
 801         }
 802         while (delp--)
 803                 free(del[delp]);
 804 }
 805
 806 static void conflict_rename_dir(struct rename *ren1,
 807                                 const char *branch1)
 808 {
 809         char *new_path = unique_path(ren1->pair->two->path, branch1);
 810         output(1, "Renamed %s to %s instead", ren1->pair->one->path, new_path);
 811         remove_file(0, ren1->pair->two->path, 0);
 812         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
 813         free(new_path);
 814 }
 815
 816 static void conflict_rename_rename_2(struct rename *ren1,
 817                                      const char *branch1,
 818                                      struct rename *ren2,
 819                                      const char *branch2)
 820 {
 821         char *new_path1 = unique_path(ren1->pair->two->path, branch1);
 822         char *new_path2 = unique_path(ren2->pair->two->path, branch2);
 823         output(1, "Renamed %s to %s and %s to %s instead",
 824                ren1->pair->one->path, new_path1,
 825                ren2->pair->one->path, new_path2);
 826         remove_file(0, ren1->pair->two->path, 0);
 827         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 828         update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 829         free(new_path2);
 830         free(new_path1);
 831 }
 832
 833 static int process_renames(struct path_list *a_renames,
 834                            struct path_list *b_renames,
 835                            const char *a_branch,
 836                            const char *b_branch)
 837 {
 838         int clean_merge = 1, i, j;
 839         struct path_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
 840         const struct rename *sre;
 841
 842         for (i = 0; i < a_renames->nr; i++) {
 843                 sre = a_renames->items[i].util;
 844                 path_list_insert(sre->pair->two->path, &a_by_dst)->util
 845                         = sre->dst_entry;
 846         }
 847         for (i = 0; i < b_renames->nr; i++) {
 848                 sre = b_renames->items[i].util;
 849                 path_list_insert(sre->pair->two->path, &b_by_dst)->util
 850                         = sre->dst_entry;
 851         }
 852
 853         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 854                 int compare;
 855                 char *src;
 856                 struct path_list *renames1, *renames2, *renames2Dst;
 857                 struct rename *ren1 = NULL, *ren2 = NULL;
 858                 const char *branch1, *branch2;
 859                 const char *ren1_src, *ren1_dst;
 860
 861                 if (i >= a_renames->nr) {
 862                         compare = 1;
 863                         ren2 = b_renames->items[j++].util;
 864                 } else if (j >= b_renames->nr) {
 865                         compare = -1;
 866                         ren1 = a_renames->items[i++].util;
 867                 } else {
 868                         compare = strcmp(a_renames->items[i].path,
 869                                         b_renames->items[j].path);
 870                         if (compare <= 0)
 871                                 ren1 = a_renames->items[i++].util;
 872                         if (compare >= 0)
 873                                 ren2 = b_renames->items[j++].util;
 874                 }
 875
 876                 /* TODO: refactor, so that 1/2 are not needed */
 877                 if (ren1) {
 878                         renames1 = a_renames;
 879                         renames2 = b_renames;
 880                         renames2Dst = &b_by_dst;
 881                         branch1 = a_branch;
 882                         branch2 = b_branch;
 883                 } else {
 884                         struct rename *tmp;
 885                         renames1 = b_renames;
 886                         renames2 = a_renames;
 887                         renames2Dst = &a_by_dst;
 888                         branch1 = b_branch;
 889                         branch2 = a_branch;
 890                         tmp = ren2;
 891                         ren2 = ren1;
 892                         ren1 = tmp;
 893                 }
 894                 src = ren1->pair->one->path;
 895
 896                 ren1->dst_entry->processed = 1;
 897                 ren1->src_entry->processed = 1;
 898
 899                 if (ren1->processed)
 900                         continue;
 901                 ren1->processed = 1;
 902
 903                 ren1_src = ren1->pair->one->path;
 904                 ren1_dst = ren1->pair->two->path;
 905
 906                 if (ren2) {
 907                         const char *ren2_src = ren2->pair->one->path;
 908                         const char *ren2_dst = ren2->pair->two->path;
 909                         /* Renamed in 1 and renamed in 2 */
 910                         if (strcmp(ren1_src, ren2_src) != 0)
 911                                 die("ren1.src != ren2.src");
 912                         ren2->dst_entry->processed = 1;
 913                         ren2->processed = 1;
 914                         if (strcmp(ren1_dst, ren2_dst) != 0) {
 915                                 clean_merge = 0;
 916                                 output(1, "CONFLICT (rename/rename): "
 917                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
 918                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
 919                                        src, ren1_dst, branch1,
 920                                        src, ren2_dst, branch2,
 921                                        index_only ? " (left unresolved)": "");
 922                                 if (index_only) {
 923                                         remove_file_from_cache(src);
 924                                         update_file(0, ren1->pair->one->sha1,
 925                                                     ren1->pair->one->mode, src);
 926                                 }
 927                                 conflict_rename_rename(ren1, branch1, ren2, branch2);
 928                         } else {
 929                                 struct merge_file_info mfi;
 930                                 remove_file(1, ren1_src, 1);
 931                                 mfi = merge_file(ren1->pair->one,
 932                                                  ren1->pair->two,
 933                                                  ren2->pair->two,
 934                                                  branch1,
 935                                                  branch2);
 936                                 if (mfi.merge || !mfi.clean)
 937                                         output(1, "Renamed %s->%s", src, ren1_dst);
 938
 939                                 if (mfi.merge)
 940                                         output(2, "Auto-merged %s", ren1_dst);
 941
 942                                 if (!mfi.clean) {
 943                                         output(1, "CONFLICT (content): merge conflict in %s",
 944                                                ren1_dst);
 945                                         clean_merge = 0;
 946
 947                                         if (!index_only)
 948                                                 update_stages(ren1_dst,
 949                                                               ren1->pair->one,
 950                                                               ren1->pair->two,
 951                                                               ren2->pair->two,
 952                                                               1 /* clear */);
 953                                 }
 954                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 955                         }
 956                 } else {
 957                         /* Renamed in 1, maybe changed in 2 */
 958                         struct path_list_item *item;
 959                         /* we only use sha1 and mode of these */
 960                         struct diff_filespec src_other, dst_other;
 961                         int try_merge, stage = a_renames == renames1 ? 3: 2;
 962
 963                         remove_file(1, ren1_src, index_only || stage == 3);
 964
 965                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
 966                         src_other.mode = ren1->src_entry->stages[stage].mode;
 967                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
 968                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
 969
 970                         try_merge = 0;
 971
 972                         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 973                                 clean_merge = 0;
 974                                 output(1, "CONFLICT (rename/directory): Renamed %s->%s in %s "
 975                                        " directory %s added in %s",
 976                                        ren1_src, ren1_dst, branch1,
 977                                        ren1_dst, branch2);
 978                                 conflict_rename_dir(ren1, branch1);
 979                         } else if (sha_eq(src_other.sha1, null_sha1)) {
 980                                 clean_merge = 0;
 981                                 output(1, "CONFLICT (rename/delete): Renamed %s->%s in %s "
 982                                        "and deleted in %s",
 983                                        ren1_src, ren1_dst, branch1,
 984                                        branch2);
 985                                 update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
 986                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
 987                                 const char *new_path;
 988                                 clean_merge = 0;
 989                                 try_merge = 1;
 990                                 output(1, "CONFLICT (rename/add): Renamed %s->%s in %s. "
 991                                        "%s added in %s",
 992                                        ren1_src, ren1_dst, branch1,
 993                                        ren1_dst, branch2);
 994                                 new_path = unique_path(ren1_dst, branch2);
 995                                 output(1, "Added as %s instead", new_path);
 996                                 update_file(0, dst_other.sha1, dst_other.mode, new_path);
 997                         } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
 998                                 ren2 = item->util;
 999                                 clean_merge = 0;
1000                                 ren2->processed = 1;
1001                                 output(1, "CONFLICT (rename/rename): Renamed %s->%s in %s. "
1002                                        "Renamed %s->%s in %s",
1003                                        ren1_src, ren1_dst, branch1,
1004                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
1005                                 conflict_rename_rename_2(ren1, branch1, ren2, branch2);
1006                         } else
1007                                 try_merge = 1;
1008
1009                         if (try_merge) {
1010                                 struct diff_filespec *o, *a, *b;
1011                                 struct merge_file_info mfi;
1012                                 src_other.path = (char *)ren1_src;
1013
1014                                 o = ren1->pair->one;
1015                                 if (a_renames == renames1) {
1016                                         a = ren1->pair->two;
1017                                         b = &src_other;
1018                                 } else {
1019                                         b = ren1->pair->two;
1020                                         a = &src_other;
1021                                 }
1022                                 mfi = merge_file(o, a, b,
1023                                                 a_branch, b_branch);
1024
1025                                 if (mfi.merge || !mfi.clean)
1026                                         output(1, "Renamed %s => %s", ren1_src, ren1_dst);
1027                                 if (mfi.merge)
1028                                         output(2, "Auto-merged %s", ren1_dst);
1029                                 if (!mfi.clean) {
1030                                         output(1, "CONFLICT (rename/modify): Merge conflict in %s",
1031                                                ren1_dst);
1032                                         clean_merge = 0;
1033
1034                                         if (!index_only)
1035                                                 update_stages(ren1_dst,
1036                                                                 o, a, b, 1);
1037                                 }
1038                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1039                         }
1040                 }
1041         }
1042         path_list_clear(&a_by_dst, 0);
1043         path_list_clear(&b_by_dst, 0);
1044
1045         return clean_merge;
1046 }
1047
1048 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1049 {
1050         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1051 }
1052
1053 /* Per entry merge function */
1054 static int process_entry(const char *path, struct stage_data *entry,
1055                          const char *branch1,
1056                          const char *branch2)
1057 {
1058         /*
1059         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1060         print_index_entry("\tpath: ", entry);
1061         */
1062         int clean_merge = 1;
1063         unsigned o_mode = entry->stages[1].mode;
1064         unsigned a_mode = entry->stages[2].mode;
1065         unsigned b_mode = entry->stages[3].mode;
1066         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1067         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1068         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1069
1070         if (o_sha && (!a_sha || !b_sha)) {
1071                 /* Case A: Deleted in one */
1072                 if ((!a_sha && !b_sha) ||
1073                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1074                     (!a_sha && sha_eq(b_sha, o_sha))) {
1075                         /* Deleted in both or deleted in one and
1076                          * unchanged in the other */
1077                         if (a_sha)
1078                                 output(2, "Removed %s", path);
1079                         /* do not touch working file if it did not exist */
1080                         remove_file(1, path, !a_sha);
1081                 } else {
1082                         /* Deleted in one and changed in the other */
1083                         clean_merge = 0;
1084                         if (!a_sha) {
1085                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1086                                        "and modified in %s. Version %s of %s left in tree.",
1087                                        path, branch1,
1088                                        branch2, branch2, path);
1089                                 update_file(0, b_sha, b_mode, path);
1090                         } else {
1091                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1092                                        "and modified in %s. Version %s of %s left in tree.",
1093                                        path, branch2,
1094                                        branch1, branch1, path);
1095                                 update_file(0, a_sha, a_mode, path);
1096                         }
1097                 }
1098
1099         } else if ((!o_sha && a_sha && !b_sha) ||
1100                    (!o_sha && !a_sha && b_sha)) {
1101                 /* Case B: Added in one. */
1102                 const char *add_branch;
1103                 const char *other_branch;
1104                 unsigned mode;
1105                 const unsigned char *sha;
1106                 const char *conf;
1107
1108                 if (a_sha) {
1109                         add_branch = branch1;
1110                         other_branch = branch2;
1111                         mode = a_mode;
1112                         sha = a_sha;
1113                         conf = "file/directory";
1114                 } else {
1115                         add_branch = branch2;
1116                         other_branch = branch1;
1117                         mode = b_mode;
1118                         sha = b_sha;
1119                         conf = "directory/file";
1120                 }
1121                 if (path_list_has_path(&current_directory_set, path)) {
1122                         const char *new_path = unique_path(path, add_branch);
1123                         clean_merge = 0;
1124                         output(1, "CONFLICT (%s): There is a directory with name %s in %s. "
1125                                "Added %s as %s",
1126                                conf, path, other_branch, path, new_path);
1127                         remove_file(0, path, 0);
1128                         update_file(0, sha, mode, new_path);
1129                 } else {
1130                         output(2, "Added %s", path);
1131                         update_file(1, sha, mode, path);
1132                 }
1133         } else if (a_sha && b_sha) {
1134                 /* Case C: Added in both (check for same permissions) and */
1135                 /* case D: Modified in both, but differently. */
1136                 const char *reason = "content";
1137                 struct merge_file_info mfi;
1138                 struct diff_filespec o, a, b;
1139
1140                 if (!o_sha) {
1141                         reason = "add/add";
1142                         o_sha = (unsigned char *)null_sha1;
1143                 }
1144                 output(2, "Auto-merged %s", path);
1145                 o.path = a.path = b.path = (char *)path;
1146                 hashcpy(o.sha1, o_sha);
1147                 o.mode = o_mode;
1148                 hashcpy(a.sha1, a_sha);
1149                 a.mode = a_mode;
1150                 hashcpy(b.sha1, b_sha);
1151                 b.mode = b_mode;
1152
1153                 mfi = merge_file(&o, &a, &b,
1154                                  branch1, branch2);
1155
1156                 if (mfi.clean)
1157                         update_file(1, mfi.sha, mfi.mode, path);
1158                 else {
1159                         clean_merge = 0;
1160                         output(1, "CONFLICT (%s): Merge conflict in %s",
1161                                         reason, path);
1162
1163                         if (index_only)
1164                                 update_file(0, mfi.sha, mfi.mode, path);
1165                         else
1166                                 update_file_flags(mfi.sha, mfi.mode, path,
1167                                               0 /* update_cache */, 1 /* update_working_directory */);
1168                 }
1169         } else if (!o_sha && !a_sha && !b_sha) {
1170                 /*
1171                  * this entry was deleted altogether. a_mode == 0 means
1172                  * we had that path and want to actively remove it.
1173                  */
1174                 remove_file(1, path, !a_mode);
1175         } else
1176                 die("Fatal merge failure, shouldn't happen.");
1177
1178         return clean_merge;
1179 }
1180
1181 static int merge_trees(struct tree *head,
1182                        struct tree *merge,
1183                        struct tree *common,
1184                        const char *branch1,
1185                        const char *branch2,
1186                        struct tree **result)
1187 {
1188         int code, clean;
1189
1190         if (subtree_merge) {
1191                 merge = shift_tree_object(head, merge);
1192                 common = shift_tree_object(head, common);
1193         }
1194
1195         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1196                 output(0, "Already uptodate!");
1197                 *result = head;
1198                 return 1;
1199         }
1200
1201         code = git_merge_trees(index_only, common, head, merge);
1202
1203         if (code != 0)
1204                 die("merging of trees %s and %s failed",
1205                     sha1_to_hex(head->object.sha1),
1206                     sha1_to_hex(merge->object.sha1));
1207
1208         if (unmerged_index()) {
1209                 struct path_list *entries, *re_head, *re_merge;
1210                 int i;
1211                 path_list_clear(&current_file_set, 1);
1212                 path_list_clear(&current_directory_set, 1);
1213                 get_files_dirs(head);
1214                 get_files_dirs(merge);
1215
1216                 entries = get_unmerged();
1217                 re_head  = get_renames(head, common, head, merge, entries);
1218                 re_merge = get_renames(merge, common, head, merge, entries);
1219                 clean = process_renames(re_head, re_merge,
1220                                 branch1, branch2);
1221                 total_cnt += entries->nr;
1222                 for (i = 0; i < entries->nr; i++, merged_cnt++) {
1223                         const char *path = entries->items[i].path;
1224                         struct stage_data *e = entries->items[i].util;
1225                         if (!e->processed
1226                                 && !process_entry(path, e, branch1, branch2))
1227                                 clean = 0;
1228                         if (do_progress)
1229                                 display_progress();
1230                 }
1231
1232                 path_list_clear(re_merge, 0);
1233                 path_list_clear(re_head, 0);
1234                 path_list_clear(entries, 1);
1235
1236         }
1237         else
1238                 clean = 1;
1239
1240         if (index_only)
1241                 *result = git_write_tree();
1242
1243         return clean;
1244 }
1245
1246 static struct commit_list *reverse_commit_list(struct commit_list *list)
1247 {
1248         struct commit_list *next = NULL, *current, *backup;
1249         for (current = list; current; current = backup) {
1250                 backup = current->next;
1251                 current->next = next;
1252                 next = current;
1253         }
1254         return next;
1255 }
1256
1257 /*
1258  * Merge the commits h1 and h2, return the resulting virtual
1259  * commit object and a flag indicating the cleanness of the merge.
1260  */
1261 static int merge(struct commit *h1,
1262                  struct commit *h2,
1263                  const char *branch1,
1264                  const char *branch2,
1265                  struct commit_list *ca,
1266                  struct commit **result)
1267 {
1268         struct commit_list *iter;
1269         struct commit *merged_common_ancestors;
1270         struct tree *mrtree;
1271         int clean;
1272
1273         if (show(4)) {
1274                 output(4, "Merging:");
1275                 output_commit_title(h1);
1276                 output_commit_title(h2);
1277         }
1278
1279         if (!ca) {
1280                 ca = get_merge_bases(h1, h2, 1);
1281                 ca = reverse_commit_list(ca);
1282         }
1283
1284         if (show(5)) {
1285                 output(5, "found %u common ancestor(s):", commit_list_count(ca));
1286                 for (iter = ca; iter; iter = iter->next)
1287                         output_commit_title(iter->item);
1288         }
1289
1290         merged_common_ancestors = pop_commit(&ca);
1291         if (merged_common_ancestors == NULL) {
1292                 /* if there is no common ancestor, make an empty tree */
1293                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1294
1295                 tree->object.parsed = 1;
1296                 tree->object.type = OBJ_TREE;
1297                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1298                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1299         }
1300
1301         for (iter = ca; iter; iter = iter->next) {
1302                 call_depth++;
1303                 /*
1304                  * When the merge fails, the result contains files
1305                  * with conflict markers. The cleanness flag is
1306                  * ignored, it was never actually used, as result of
1307                  * merge_trees has always overwritten it: the committed
1308                  * "conflicts" were already resolved.
1309                  */
1310                 discard_cache();
1311                 merge(merged_common_ancestors, iter->item,
1312                       "Temporary merge branch 1",
1313                       "Temporary merge branch 2",
1314                       NULL,
1315                       &merged_common_ancestors);
1316                 call_depth--;
1317
1318                 if (!merged_common_ancestors)
1319                         die("merge returned no commit");
1320         }
1321
1322         discard_cache();
1323         if (!call_depth) {
1324                 read_cache();
1325                 index_only = 0;
1326         } else
1327                 index_only = 1;
1328
1329         clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
1330                             branch1, branch2, &mrtree);
1331
1332         if (index_only) {
1333                 *result = make_virtual_commit(mrtree, "merged tree");
1334                 commit_list_insert(h1, &(*result)->parents);
1335                 commit_list_insert(h2, &(*result)->parents->next);
1336         }
1337         if (!call_depth && do_progress) {
1338                 /* Make sure we end at 100% */
1339                 if (!total_cnt)
1340                         total_cnt = 1;
1341                 merged_cnt = total_cnt;
1342                 progress_update = 1;
1343                 display_progress();
1344                 fputc('\n', stderr);
1345         }
1346         flush_output();
1347         return clean;
1348 }
1349
1350 static const char *better_branch_name(const char *branch)
1351 {
1352         static char githead_env[8 + 40 + 1];
1353         char *name;
1354
1355         if (strlen(branch) != 40)
1356                 return branch;
1357         sprintf(githead_env, "GITHEAD_%s", branch);
1358         name = getenv(githead_env);
1359         return name ? name : branch;
1360 }
1361
1362 static struct commit *get_ref(const char *ref)
1363 {
1364         unsigned char sha1[20];
1365         struct object *object;
1366
1367         if (get_sha1(ref, sha1))
1368                 die("Could not resolve ref '%s'", ref);
1369         object = deref_tag(parse_object(sha1), ref, strlen(ref));
1370         if (object->type == OBJ_TREE)
1371                 return make_virtual_commit((struct tree*)object,
1372                         better_branch_name(ref));
1373         if (object->type != OBJ_COMMIT)
1374                 return NULL;
1375         if (parse_commit((struct commit *)object))
1376                 die("Could not parse commit '%s'", sha1_to_hex(object->sha1));
1377         return (struct commit *)object;
1378 }
1379
1380 static int merge_config(const char *var, const char *value)
1381 {
1382         if (!strcasecmp(var, "merge.verbosity")) {
1383                 verbosity = git_config_int(var, value);
1384                 return 0;
1385         }
1386         return git_default_config(var, value);
1387 }
1388
1389 int main(int argc, char *argv[])
1390 {
1391         static const char *bases[20];
1392         static unsigned bases_count = 0;
1393         int i, clean;
1394         const char *branch1, *branch2;
1395         struct commit *result, *h1, *h2;
1396         struct commit_list *ca = NULL;
1397         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1398         int index_fd;
1399
1400         if (argv[0]) {
1401                 int namelen = strlen(argv[0]);
1402                 if (8 < namelen &&
1403                     !strcmp(argv[0] + namelen - 8, "-subtree"))
1404                         subtree_merge = 1;
1405         }
1406
1407         git_config(merge_config);
1408         if (getenv("GIT_MERGE_VERBOSITY"))
1409                 verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1410
1411         if (argc < 4)
1412                 die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
1413
1414         for (i = 1; i < argc; ++i) {
1415                 if (!strcmp(argv[i], "--"))
1416                         break;
1417                 if (bases_count < sizeof(bases)/sizeof(*bases))
1418                         bases[bases_count++] = argv[i];
1419         }
1420         if (argc - i != 3) /* "--" "<head>" "<remote>" */
1421                 die("Not handling anything other than two heads merge.");
1422         if (verbosity >= 5) {
1423                 buffer_output = 0;
1424                 do_progress = 0;
1425         }
1426         else
1427                 do_progress = isatty(1);
1428
1429         branch1 = argv[++i];
1430         branch2 = argv[++i];
1431
1432         h1 = get_ref(branch1);
1433         h2 = get_ref(branch2);
1434
1435         branch1 = better_branch_name(branch1);
1436         branch2 = better_branch_name(branch2);
1437
1438         if (do_progress)
1439                 setup_progress_signal();
1440         if (show(3))
1441                 printf("Merging %s with %s\n", branch1, branch2);
1442
1443         index_fd = hold_locked_index(lock, 1);
1444
1445         for (i = 0; i < bases_count; i++) {
1446                 struct commit *ancestor = get_ref(bases[i]);
1447                 ca = commit_list_insert(ancestor, &ca);
1448         }
1449         clean = merge(h1, h2, branch1, branch2, ca, &result);
1450
1451         if (active_cache_changed &&
1452             (write_cache(index_fd, active_cache, active_nr) ||
1453              close(index_fd) || commit_locked_index(lock)))
1454                         die ("unable to write %s", get_index_file());
1455
1456         return clean ? 0: 1;
1457 }