builtin-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 "builtin.h"
  11 #include "tree-walk.h"
  12 #include "diff.h"
  13 #include "diffcore.h"
  14 #include "tag.h"
  15 #include "unpack-trees.h"
  16 #include "path-list.h"
  17 #include "xdiff-interface.h"
  18 #include "ll-merge.h"
  19 #include "interpolate.h"
  20 #include "attr.h"
  21 #include "merge-recursive.h"
  22
  23 static int subtree_merge;
  24
  25 static struct tree *shift_tree_object(struct tree *one, struct tree *two)
  26 {
  27         unsigned char shifted[20];
  28
  29         /*
  30          * NEEDSWORK: this limits the recursion depth to hardcoded
  31          * value '2' to avoid excessive overhead.
  32          */
  33         shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
  34         if (!hashcmp(two->object.sha1, shifted))
  35                 return two;
  36         return lookup_tree(shifted);
  37 }
  38
  39 /*
  40  * A virtual commit has
  41  * - (const char *)commit->util set to the name, and
  42  * - *(int *)commit->object.sha1 set to the virtual id.
  43  */
  44
  45 static unsigned commit_list_count(const struct commit_list *l)
  46 {
  47         unsigned c = 0;
  48         for (; l; l = l->next )
  49                 c++;
  50         return c;
  51 }
  52
  53 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  54 {
  55         struct commit *commit = xcalloc(1, sizeof(struct commit));
  56         static unsigned virtual_id = 1;
  57         commit->tree = tree;
  58         commit->util = (void*)comment;
  59         *(int*)commit->object.sha1 = virtual_id++;
  60         /* avoid warnings */
  61         commit->object.parsed = 1;
  62         return commit;
  63 }
  64
  65 /*
  66  * Since we use get_tree_entry(), which does not put the read object into
  67  * the object pool, we cannot rely on a == b.
  68  */
  69 static int sha_eq(const unsigned char *a, const unsigned char *b)
  70 {
  71         if (!a && !b)
  72                 return 2;
  73         return a && b && hashcmp(a, b) == 0;
  74 }
  75
  76 /*
  77  * Since we want to write the index eventually, we cannot reuse the index
  78  * for these (temporary) data.
  79  */
  80 struct stage_data
  81 {
  82         struct
  83         {
  84                 unsigned mode;
  85                 unsigned char sha[20];
  86         } stages[4];
  87         unsigned processed:1;
  88 };
  89
  90 static struct path_list current_file_set = {NULL, 0, 0, 1};
  91 static struct path_list current_directory_set = {NULL, 0, 0, 1};
  92
  93 static int call_depth = 0;
  94 static int verbosity = 2;
  95 static int diff_rename_limit = -1;
  96 static int merge_rename_limit = -1;
  97 static int buffer_output = 1;
  98 static struct strbuf obuf = STRBUF_INIT;
  99
 100 static int show(int v)
 101 {
 102         return (!call_depth && verbosity >= v) || verbosity >= 5;
 103 }
 104
 105 static void flush_output(void)
 106 {
 107         if (obuf.len) {
 108                 fputs(obuf.buf, stdout);
 109                 strbuf_reset(&obuf);
 110         }
 111 }
 112
 113 static void output(int v, const char *fmt, ...)
 114 {
 115         int len;
 116         va_list ap;
 117
 118         if (!show(v))
 119                 return;
 120
 121         strbuf_grow(&obuf, call_depth * 2 + 2);
 122         memset(obuf.buf + obuf.len, ' ', call_depth * 2);
 123         strbuf_setlen(&obuf, obuf.len + call_depth * 2);
 124
 125         va_start(ap, fmt);
 126         len = vsnprintf(obuf.buf + obuf.len, strbuf_avail(&obuf), fmt, ap);
 127         va_end(ap);
 128
 129         if (len < 0)
 130                 len = 0;
 131         if (len >= strbuf_avail(&obuf)) {
 132                 strbuf_grow(&obuf, len + 2);
 133                 va_start(ap, fmt);
 134                 len = vsnprintf(obuf.buf + obuf.len, strbuf_avail(&obuf), fmt, ap);
 135                 va_end(ap);
 136                 if (len >= strbuf_avail(&obuf)) {
 137                         die("this should not happen, your snprintf is broken");
 138                 }
 139         }
 140         strbuf_setlen(&obuf, obuf.len + len);
 141         strbuf_add(&obuf, "\n", 1);
 142         if (!buffer_output)
 143                 flush_output();
 144 }
 145
 146 static void output_commit_title(struct commit *commit)
 147 {
 148         int i;
 149         flush_output();
 150         for (i = call_depth; i--;)
 151                 fputs("  ", stdout);
 152         if (commit->util)
 153                 printf("virtual %s\n", (char *)commit->util);
 154         else {
 155                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 156                 if (parse_commit(commit) != 0)
 157                         printf("(bad commit)\n");
 158                 else {
 159                         const char *s;
 160                         int len;
 161                         for (s = commit->buffer; *s; s++)
 162                                 if (*s == '\n' && s[1] == '\n') {
 163                                         s += 2;
 164                                         break;
 165                                 }
 166                         for (len = 0; s[len] && '\n' != s[len]; len++)
 167                                 ; /* do nothing */
 168                         printf("%.*s\n", len, s);
 169                 }
 170         }
 171 }
 172
 173 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 174                 const char *path, int stage, int refresh, int options)
 175 {
 176         struct cache_entry *ce;
 177         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 178         if (!ce)
 179                 return error("addinfo_cache failed for path '%s'", path);
 180         return add_cache_entry(ce, options);
 181 }
 182
 183 /*
 184  * This is a global variable which is used in a number of places but
 185  * only written to in the 'merge' function.
 186  *
 187  * index_only == 1    => Don't leave any non-stage 0 entries in the cache and
 188  *                       don't update the working directory.
 189  *               0    => Leave unmerged entries in the cache and update
 190  *                       the working directory.
 191  */
 192 static int index_only = 0;
 193
 194 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 195 {
 196         parse_tree(tree);
 197         init_tree_desc(desc, tree->buffer, tree->size);
 198 }
 199
 200 static int git_merge_trees(int index_only,
 201                            struct tree *common,
 202                            struct tree *head,
 203                            struct tree *merge)
 204 {
 205         int rc;
 206         struct tree_desc t[3];
 207         struct unpack_trees_options opts;
 208
 209         memset(&opts, 0, sizeof(opts));
 210         if (index_only)
 211                 opts.index_only = 1;
 212         else
 213                 opts.update = 1;
 214         opts.merge = 1;
 215         opts.head_idx = 2;
 216         opts.fn = threeway_merge;
 217         opts.src_index = &the_index;
 218         opts.dst_index = &the_index;
 219
 220         init_tree_desc_from_tree(t+0, common);
 221         init_tree_desc_from_tree(t+1, head);
 222         init_tree_desc_from_tree(t+2, merge);
 223
 224         rc = unpack_trees(3, t, &opts);
 225         cache_tree_free(&active_cache_tree);
 226         return rc;
 227 }
 228
 229 struct tree *write_tree_from_memory(void)
 230 {
 231         struct tree *result = NULL;
 232
 233         if (unmerged_cache()) {
 234                 int i;
 235                 output(0, "There are unmerged index entries:");
 236                 for (i = 0; i < active_nr; i++) {
 237                         struct cache_entry *ce = active_cache[i];
 238                         if (ce_stage(ce))
 239                                 output(0, "%d %.*s", ce_stage(ce), ce_namelen(ce), ce->name);
 240                 }
 241                 return NULL;
 242         }
 243
 244         if (!active_cache_tree)
 245                 active_cache_tree = cache_tree();
 246
 247         if (!cache_tree_fully_valid(active_cache_tree) &&
 248             cache_tree_update(active_cache_tree,
 249                               active_cache, active_nr, 0, 0) < 0)
 250                 die("error building trees");
 251
 252         result = lookup_tree(active_cache_tree->sha1);
 253
 254         return result;
 255 }
 256
 257 static int save_files_dirs(const unsigned char *sha1,
 258                 const char *base, int baselen, const char *path,
 259                 unsigned int mode, int stage)
 260 {
 261         int len = strlen(path);
 262         char *newpath = xmalloc(baselen + len + 1);
 263         memcpy(newpath, base, baselen);
 264         memcpy(newpath + baselen, path, len);
 265         newpath[baselen + len] = '\0';
 266
 267         if (S_ISDIR(mode))
 268                 path_list_insert(newpath, &current_directory_set);
 269         else
 270                 path_list_insert(newpath, &current_file_set);
 271         free(newpath);
 272
 273         return READ_TREE_RECURSIVE;
 274 }
 275
 276 static int get_files_dirs(struct tree *tree)
 277 {
 278         int n;
 279         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs) != 0)
 280                 return 0;
 281         n = current_file_set.nr + current_directory_set.nr;
 282         return n;
 283 }
 284
 285 /*
 286  * Returns an index_entry instance which doesn't have to correspond to
 287  * a real cache entry in Git's index.
 288  */
 289 static struct stage_data *insert_stage_data(const char *path,
 290                 struct tree *o, struct tree *a, struct tree *b,
 291                 struct path_list *entries)
 292 {
 293         struct path_list_item *item;
 294         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 295         get_tree_entry(o->object.sha1, path,
 296                         e->stages[1].sha, &e->stages[1].mode);
 297         get_tree_entry(a->object.sha1, path,
 298                         e->stages[2].sha, &e->stages[2].mode);
 299         get_tree_entry(b->object.sha1, path,
 300                         e->stages[3].sha, &e->stages[3].mode);
 301         item = path_list_insert(path, entries);
 302         item->util = e;
 303         return e;
 304 }
 305
 306 /*
 307  * Create a dictionary mapping file names to stage_data objects. The
 308  * dictionary contains one entry for every path with a non-zero stage entry.
 309  */
 310 static struct path_list *get_unmerged(void)
 311 {
 312         struct path_list *unmerged = xcalloc(1, sizeof(struct path_list));
 313         int i;
 314
 315         unmerged->strdup_paths = 1;
 316
 317         for (i = 0; i < active_nr; i++) {
 318                 struct path_list_item *item;
 319                 struct stage_data *e;
 320                 struct cache_entry *ce = active_cache[i];
 321                 if (!ce_stage(ce))
 322                         continue;
 323
 324                 item = path_list_lookup(ce->name, unmerged);
 325                 if (!item) {
 326                         item = path_list_insert(ce->name, unmerged);
 327                         item->util = xcalloc(1, sizeof(struct stage_data));
 328                 }
 329                 e = item->util;
 330                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
 331                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 332         }
 333
 334         return unmerged;
 335 }
 336
 337 struct rename
 338 {
 339         struct diff_filepair *pair;
 340         struct stage_data *src_entry;
 341         struct stage_data *dst_entry;
 342         unsigned processed:1;
 343 };
 344
 345 /*
 346  * Get information of all renames which occurred between 'o_tree' and
 347  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 348  * 'b_tree') to be able to associate the correct cache entries with
 349  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 350  */
 351 static struct path_list *get_renames(struct tree *tree,
 352                                         struct tree *o_tree,
 353                                         struct tree *a_tree,
 354                                         struct tree *b_tree,
 355                                         struct path_list *entries)
 356 {
 357         int i;
 358         struct path_list *renames;
 359         struct diff_options opts;
 360
 361         renames = xcalloc(1, sizeof(struct path_list));
 362         diff_setup(&opts);
 363         DIFF_OPT_SET(&opts, RECURSIVE);
 364         opts.detect_rename = DIFF_DETECT_RENAME;
 365         opts.rename_limit = merge_rename_limit >= 0 ? merge_rename_limit :
 366                             diff_rename_limit >= 0 ? diff_rename_limit :
 367                             500;
 368         opts.warn_on_too_large_rename = 1;
 369         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 370         if (diff_setup_done(&opts) < 0)
 371                 die("diff setup failed");
 372         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 373         diffcore_std(&opts);
 374         for (i = 0; i < diff_queued_diff.nr; ++i) {
 375                 struct path_list_item *item;
 376                 struct rename *re;
 377                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 378                 if (pair->status != 'R') {
 379                         diff_free_filepair(pair);
 380                         continue;
 381                 }
 382                 re = xmalloc(sizeof(*re));
 383                 re->processed = 0;
 384                 re->pair = pair;
 385                 item = path_list_lookup(re->pair->one->path, entries);
 386                 if (!item)
 387                         re->src_entry = insert_stage_data(re->pair->one->path,
 388                                         o_tree, a_tree, b_tree, entries);
 389                 else
 390                         re->src_entry = item->util;
 391
 392                 item = path_list_lookup(re->pair->two->path, entries);
 393                 if (!item)
 394                         re->dst_entry = insert_stage_data(re->pair->two->path,
 395                                         o_tree, a_tree, b_tree, entries);
 396                 else
 397                         re->dst_entry = item->util;
 398                 item = path_list_insert(pair->one->path, renames);
 399                 item->util = re;
 400         }
 401         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 402         diff_queued_diff.nr = 0;
 403         diff_flush(&opts);
 404         return renames;
 405 }
 406
 407 static int update_stages(const char *path, struct diff_filespec *o,
 408                          struct diff_filespec *a, struct diff_filespec *b,
 409                          int clear)
 410 {
 411         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 412         if (clear)
 413                 if (remove_file_from_cache(path))
 414                         return -1;
 415         if (o)
 416                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 417                         return -1;
 418         if (a)
 419                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 420                         return -1;
 421         if (b)
 422                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 423                         return -1;
 424         return 0;
 425 }
 426
 427 static int remove_path(const char *name)
 428 {
 429         int ret;
 430         char *slash, *dirs;
 431
 432         ret = unlink(name);
 433         if (ret)
 434                 return ret;
 435         dirs = xstrdup(name);
 436         while ((slash = strrchr(name, '/'))) {
 437                 *slash = '\0';
 438                 if (rmdir(name) != 0)
 439                         break;
 440         }
 441         free(dirs);
 442         return ret;
 443 }
 444
 445 static int remove_file(int clean, const char *path, int no_wd)
 446 {
 447         int update_cache = index_only || clean;
 448         int update_working_directory = !index_only && !no_wd;
 449
 450         if (update_cache) {
 451                 if (remove_file_from_cache(path))
 452                         return -1;
 453         }
 454         if (update_working_directory) {
 455                 unlink(path);
 456                 if (errno != ENOENT || errno != EISDIR)
 457                         return -1;
 458                 remove_path(path);
 459         }
 460         return 0;
 461 }
 462
 463 static char *unique_path(const char *path, const char *branch)
 464 {
 465         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 466         int suffix = 0;
 467         struct stat st;
 468         char *p = newpath + strlen(path);
 469         strcpy(newpath, path);
 470         *(p++) = '~';
 471         strcpy(p, branch);
 472         for (; *p; ++p)
 473                 if ('/' == *p)
 474                         *p = '_';
 475         while (path_list_has_path(&current_file_set, newpath) ||
 476                path_list_has_path(&current_directory_set, newpath) ||
 477                lstat(newpath, &st) == 0)
 478                 sprintf(p, "_%d", suffix++);
 479
 480         path_list_insert(newpath, &current_file_set);
 481         return newpath;
 482 }
 483
 484 static void flush_buffer(int fd, const char *buf, unsigned long size)
 485 {
 486         while (size > 0) {
 487                 long ret = write_in_full(fd, buf, size);
 488                 if (ret < 0) {
 489                         /* Ignore epipe */
 490                         if (errno == EPIPE)
 491                                 break;
 492                         die("merge-recursive: %s", strerror(errno));
 493                 } else if (!ret) {
 494                         die("merge-recursive: disk full?");
 495                 }
 496                 size -= ret;
 497                 buf += ret;
 498         }
 499 }
 500
 501 static int make_room_for_path(const char *path)
 502 {
 503         int status;
 504         const char *msg = "failed to create path '%s'%s";
 505
 506         status = safe_create_leading_directories_const(path);
 507         if (status) {
 508                 if (status == -3) {
 509                         /* something else exists */
 510                         error(msg, path, ": perhaps a D/F conflict?");
 511                         return -1;
 512                 }
 513                 die(msg, path, "");
 514         }
 515
 516         /* Successful unlink is good.. */
 517         if (!unlink(path))
 518                 return 0;
 519         /* .. and so is no existing file */
 520         if (errno == ENOENT)
 521                 return 0;
 522         /* .. but not some other error (who really cares what?) */
 523         return error(msg, path, ": perhaps a D/F conflict?");
 524 }
 525
 526 static void update_file_flags(const unsigned char *sha,
 527                               unsigned mode,
 528                               const char *path,
 529                               int update_cache,
 530                               int update_wd)
 531 {
 532         if (index_only)
 533                 update_wd = 0;
 534
 535         if (update_wd) {
 536                 enum object_type type;
 537                 void *buf;
 538                 unsigned long size;
 539
 540                 if (S_ISGITLINK(mode))
 541                         die("cannot read object %s '%s': It is a submodule!",
 542                             sha1_to_hex(sha), path);
 543
 544                 buf = read_sha1_file(sha, &type, &size);
 545                 if (!buf)
 546                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 547                 if (type != OBJ_BLOB)
 548                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 549                 if (S_ISREG(mode)) {
 550                         struct strbuf strbuf;
 551                         strbuf_init(&strbuf, 0);
 552                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
 553                                 free(buf);
 554                                 size = strbuf.len;
 555                                 buf = strbuf_detach(&strbuf, NULL);
 556                         }
 557                 }
 558
 559                 if (make_room_for_path(path) < 0) {
 560                         update_wd = 0;
 561                         free(buf);
 562                         goto update_index;
 563                 }
 564                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 565                         int fd;
 566                         if (mode & 0100)
 567                                 mode = 0777;
 568                         else
 569                                 mode = 0666;
 570                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 571                         if (fd < 0)
 572                                 die("failed to open %s: %s", path, strerror(errno));
 573                         flush_buffer(fd, buf, size);
 574                         close(fd);
 575                 } else if (S_ISLNK(mode)) {
 576                         char *lnk = xmemdupz(buf, size);
 577                         safe_create_leading_directories_const(path);
 578                         unlink(path);
 579                         symlink(lnk, path);
 580                         free(lnk);
 581                 } else
 582                         die("do not know what to do with %06o %s '%s'",
 583                             mode, sha1_to_hex(sha), path);
 584                 free(buf);
 585         }
 586  update_index:
 587         if (update_cache)
 588                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 589 }
 590
 591 static void update_file(int clean,
 592                         const unsigned char *sha,
 593                         unsigned mode,
 594                         const char *path)
 595 {
 596         update_file_flags(sha, mode, path, index_only || clean, !index_only);
 597 }
 598
 599 /* Low level file merging, update and removal */
 600
 601 struct merge_file_info
 602 {
 603         unsigned char sha[20];
 604         unsigned mode;
 605         unsigned clean:1,
 606                  merge:1;
 607 };
 608
 609 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 610 {
 611         unsigned long size;
 612         enum object_type type;
 613
 614         if (!hashcmp(sha1, null_sha1)) {
 615                 mm->ptr = xstrdup("");
 616                 mm->size = 0;
 617                 return;
 618         }
 619
 620         mm->ptr = read_sha1_file(sha1, &type, &size);
 621         if (!mm->ptr || type != OBJ_BLOB)
 622                 die("unable to read blob object %s", sha1_to_hex(sha1));
 623         mm->size = size;
 624 }
 625
 626 static int merge_3way(mmbuffer_t *result_buf,
 627                       struct diff_filespec *o,
 628                       struct diff_filespec *a,
 629                       struct diff_filespec *b,
 630                       const char *branch1,
 631                       const char *branch2)
 632 {
 633         mmfile_t orig, src1, src2;
 634         char *name1, *name2;
 635         int merge_status;
 636
 637         name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 638         name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 639
 640         fill_mm(o->sha1, &orig);
 641         fill_mm(a->sha1, &src1);
 642         fill_mm(b->sha1, &src2);
 643
 644         merge_status = ll_merge(result_buf, a->path, &orig,
 645                                 &src1, name1, &src2, name2,
 646                                 index_only);
 647
 648         free(name1);
 649         free(name2);
 650         free(orig.ptr);
 651         free(src1.ptr);
 652         free(src2.ptr);
 653         return merge_status;
 654 }
 655
 656 static struct merge_file_info merge_file(struct diff_filespec *o,
 657                 struct diff_filespec *a, struct diff_filespec *b,
 658                 const char *branch1, const char *branch2)
 659 {
 660         struct merge_file_info result;
 661         result.merge = 0;
 662         result.clean = 1;
 663
 664         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 665                 result.clean = 0;
 666                 if (S_ISREG(a->mode)) {
 667                         result.mode = a->mode;
 668                         hashcpy(result.sha, a->sha1);
 669                 } else {
 670                         result.mode = b->mode;
 671                         hashcpy(result.sha, b->sha1);
 672                 }
 673         } else {
 674                 if (!sha_eq(a->sha1, o->sha1) && !sha_eq(b->sha1, o->sha1))
 675                         result.merge = 1;
 676
 677                 /*
 678                  * Merge modes
 679                  */
 680                 if (a->mode == b->mode || a->mode == o->mode)
 681                         result.mode = b->mode;
 682                 else {
 683                         result.mode = a->mode;
 684                         if (b->mode != o->mode) {
 685                                 result.clean = 0;
 686                                 result.merge = 1;
 687                         }
 688                 }
 689
 690                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, o->sha1))
 691                         hashcpy(result.sha, b->sha1);
 692                 else if (sha_eq(b->sha1, o->sha1))
 693                         hashcpy(result.sha, a->sha1);
 694                 else if (S_ISREG(a->mode)) {
 695                         mmbuffer_t result_buf;
 696                         int merge_status;
 697
 698                         merge_status = merge_3way(&result_buf, o, a, b,
 699                                                   branch1, branch2);
 700
 701                         if ((merge_status < 0) || !result_buf.ptr)
 702                                 die("Failed to execute internal merge");
 703
 704                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 705                                             blob_type, result.sha))
 706                                 die("Unable to add %s to database",
 707                                     a->path);
 708
 709                         free(result_buf.ptr);
 710                         result.clean = (merge_status == 0);
 711                 } else if (S_ISGITLINK(a->mode)) {
 712                         result.clean = 0;
 713                         hashcpy(result.sha, a->sha1);
 714                 } else if (S_ISLNK(a->mode)) {
 715                         hashcpy(result.sha, a->sha1);
 716
 717                         if (!sha_eq(a->sha1, b->sha1))
 718                                 result.clean = 0;
 719                 } else {
 720                         die("unsupported object type in the tree");
 721                 }
 722         }
 723
 724         return result;
 725 }
 726
 727 static void conflict_rename_rename(struct rename *ren1,
 728                                    const char *branch1,
 729                                    struct rename *ren2,
 730                                    const char *branch2)
 731 {
 732         char *del[2];
 733         int delp = 0;
 734         const char *ren1_dst = ren1->pair->two->path;
 735         const char *ren2_dst = ren2->pair->two->path;
 736         const char *dst_name1 = ren1_dst;
 737         const char *dst_name2 = ren2_dst;
 738         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 739                 dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
 740                 output(1, "%s is a directory in %s added as %s instead",
 741                        ren1_dst, branch2, dst_name1);
 742                 remove_file(0, ren1_dst, 0);
 743         }
 744         if (path_list_has_path(&current_directory_set, ren2_dst)) {
 745                 dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
 746                 output(1, "%s is a directory in %s added as %s instead",
 747                        ren2_dst, branch1, dst_name2);
 748                 remove_file(0, ren2_dst, 0);
 749         }
 750         if (index_only) {
 751                 remove_file_from_cache(dst_name1);
 752                 remove_file_from_cache(dst_name2);
 753                 /*
 754                  * Uncomment to leave the conflicting names in the resulting tree
 755                  *
 756                  * update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
 757                  * update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
 758                  */
 759         } else {
 760                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
 761                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
 762         }
 763         while (delp--)
 764                 free(del[delp]);
 765 }
 766
 767 static void conflict_rename_dir(struct rename *ren1,
 768                                 const char *branch1)
 769 {
 770         char *new_path = unique_path(ren1->pair->two->path, branch1);
 771         output(1, "Renamed %s to %s instead", ren1->pair->one->path, new_path);
 772         remove_file(0, ren1->pair->two->path, 0);
 773         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
 774         free(new_path);
 775 }
 776
 777 static void conflict_rename_rename_2(struct rename *ren1,
 778                                      const char *branch1,
 779                                      struct rename *ren2,
 780                                      const char *branch2)
 781 {
 782         char *new_path1 = unique_path(ren1->pair->two->path, branch1);
 783         char *new_path2 = unique_path(ren2->pair->two->path, branch2);
 784         output(1, "Renamed %s to %s and %s to %s instead",
 785                ren1->pair->one->path, new_path1,
 786                ren2->pair->one->path, new_path2);
 787         remove_file(0, ren1->pair->two->path, 0);
 788         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 789         update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 790         free(new_path2);
 791         free(new_path1);
 792 }
 793
 794 static int process_renames(struct path_list *a_renames,
 795                            struct path_list *b_renames,
 796                            const char *a_branch,
 797                            const char *b_branch)
 798 {
 799         int clean_merge = 1, i, j;
 800         struct path_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
 801         const struct rename *sre;
 802
 803         for (i = 0; i < a_renames->nr; i++) {
 804                 sre = a_renames->items[i].util;
 805                 path_list_insert(sre->pair->two->path, &a_by_dst)->util
 806                         = sre->dst_entry;
 807         }
 808         for (i = 0; i < b_renames->nr; i++) {
 809                 sre = b_renames->items[i].util;
 810                 path_list_insert(sre->pair->two->path, &b_by_dst)->util
 811                         = sre->dst_entry;
 812         }
 813
 814         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 815                 int compare;
 816                 char *src;
 817                 struct path_list *renames1, *renames2, *renames2Dst;
 818                 struct rename *ren1 = NULL, *ren2 = NULL;
 819                 const char *branch1, *branch2;
 820                 const char *ren1_src, *ren1_dst;
 821
 822                 if (i >= a_renames->nr) {
 823                         compare = 1;
 824                         ren2 = b_renames->items[j++].util;
 825                 } else if (j >= b_renames->nr) {
 826                         compare = -1;
 827                         ren1 = a_renames->items[i++].util;
 828                 } else {
 829                         compare = strcmp(a_renames->items[i].path,
 830                                         b_renames->items[j].path);
 831                         if (compare <= 0)
 832                                 ren1 = a_renames->items[i++].util;
 833                         if (compare >= 0)
 834                                 ren2 = b_renames->items[j++].util;
 835                 }
 836
 837                 /* TODO: refactor, so that 1/2 are not needed */
 838                 if (ren1) {
 839                         renames1 = a_renames;
 840                         renames2 = b_renames;
 841                         renames2Dst = &b_by_dst;
 842                         branch1 = a_branch;
 843                         branch2 = b_branch;
 844                 } else {
 845                         struct rename *tmp;
 846                         renames1 = b_renames;
 847                         renames2 = a_renames;
 848                         renames2Dst = &a_by_dst;
 849                         branch1 = b_branch;
 850                         branch2 = a_branch;
 851                         tmp = ren2;
 852                         ren2 = ren1;
 853                         ren1 = tmp;
 854                 }
 855                 src = ren1->pair->one->path;
 856
 857                 ren1->dst_entry->processed = 1;
 858                 ren1->src_entry->processed = 1;
 859
 860                 if (ren1->processed)
 861                         continue;
 862                 ren1->processed = 1;
 863
 864                 ren1_src = ren1->pair->one->path;
 865                 ren1_dst = ren1->pair->two->path;
 866
 867                 if (ren2) {
 868                         const char *ren2_src = ren2->pair->one->path;
 869                         const char *ren2_dst = ren2->pair->two->path;
 870                         /* Renamed in 1 and renamed in 2 */
 871                         if (strcmp(ren1_src, ren2_src) != 0)
 872                                 die("ren1.src != ren2.src");
 873                         ren2->dst_entry->processed = 1;
 874                         ren2->processed = 1;
 875                         if (strcmp(ren1_dst, ren2_dst) != 0) {
 876                                 clean_merge = 0;
 877                                 output(1, "CONFLICT (rename/rename): "
 878                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
 879                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
 880                                        src, ren1_dst, branch1,
 881                                        src, ren2_dst, branch2,
 882                                        index_only ? " (left unresolved)": "");
 883                                 if (index_only) {
 884                                         remove_file_from_cache(src);
 885                                         update_file(0, ren1->pair->one->sha1,
 886                                                     ren1->pair->one->mode, src);
 887                                 }
 888                                 conflict_rename_rename(ren1, branch1, ren2, branch2);
 889                         } else {
 890                                 struct merge_file_info mfi;
 891                                 remove_file(1, ren1_src, 1);
 892                                 mfi = merge_file(ren1->pair->one,
 893                                                  ren1->pair->two,
 894                                                  ren2->pair->two,
 895                                                  branch1,
 896                                                  branch2);
 897                                 if (mfi.merge || !mfi.clean)
 898                                         output(1, "Renamed %s->%s", src, ren1_dst);
 899
 900                                 if (mfi.merge)
 901                                         output(2, "Auto-merged %s", ren1_dst);
 902
 903                                 if (!mfi.clean) {
 904                                         output(1, "CONFLICT (content): merge conflict in %s",
 905                                                ren1_dst);
 906                                         clean_merge = 0;
 907
 908                                         if (!index_only)
 909                                                 update_stages(ren1_dst,
 910                                                               ren1->pair->one,
 911                                                               ren1->pair->two,
 912                                                               ren2->pair->two,
 913                                                               1 /* clear */);
 914                                 }
 915                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 916                         }
 917                 } else {
 918                         /* Renamed in 1, maybe changed in 2 */
 919                         struct path_list_item *item;
 920                         /* we only use sha1 and mode of these */
 921                         struct diff_filespec src_other, dst_other;
 922                         int try_merge, stage = a_renames == renames1 ? 3: 2;
 923
 924                         remove_file(1, ren1_src, index_only || stage == 3);
 925
 926                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
 927                         src_other.mode = ren1->src_entry->stages[stage].mode;
 928                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
 929                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
 930
 931                         try_merge = 0;
 932
 933                         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 934                                 clean_merge = 0;
 935                                 output(1, "CONFLICT (rename/directory): Renamed %s->%s in %s "
 936                                        " directory %s added in %s",
 937                                        ren1_src, ren1_dst, branch1,
 938                                        ren1_dst, branch2);
 939                                 conflict_rename_dir(ren1, branch1);
 940                         } else if (sha_eq(src_other.sha1, null_sha1)) {
 941                                 clean_merge = 0;
 942                                 output(1, "CONFLICT (rename/delete): Renamed %s->%s in %s "
 943                                        "and deleted in %s",
 944                                        ren1_src, ren1_dst, branch1,
 945                                        branch2);
 946                                 update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
 947                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
 948                                 const char *new_path;
 949                                 clean_merge = 0;
 950                                 try_merge = 1;
 951                                 output(1, "CONFLICT (rename/add): Renamed %s->%s in %s. "
 952                                        "%s added in %s",
 953                                        ren1_src, ren1_dst, branch1,
 954                                        ren1_dst, branch2);
 955                                 new_path = unique_path(ren1_dst, branch2);
 956                                 output(1, "Added as %s instead", new_path);
 957                                 update_file(0, dst_other.sha1, dst_other.mode, new_path);
 958                         } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
 959                                 ren2 = item->util;
 960                                 clean_merge = 0;
 961                                 ren2->processed = 1;
 962                                 output(1, "CONFLICT (rename/rename): Renamed %s->%s in %s. "
 963                                        "Renamed %s->%s in %s",
 964                                        ren1_src, ren1_dst, branch1,
 965                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
 966                                 conflict_rename_rename_2(ren1, branch1, ren2, branch2);
 967                         } else
 968                                 try_merge = 1;
 969
 970                         if (try_merge) {
 971                                 struct diff_filespec *o, *a, *b;
 972                                 struct merge_file_info mfi;
 973                                 src_other.path = (char *)ren1_src;
 974
 975                                 o = ren1->pair->one;
 976                                 if (a_renames == renames1) {
 977                                         a = ren1->pair->two;
 978                                         b = &src_other;
 979                                 } else {
 980                                         b = ren1->pair->two;
 981                                         a = &src_other;
 982                                 }
 983                                 mfi = merge_file(o, a, b,
 984                                                 a_branch, b_branch);
 985
 986                                 if (mfi.clean &&
 987                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
 988                                     mfi.mode == ren1->pair->two->mode)
 989                                         /*
 990                                          * This messaged is part of
 991                                          * t6022 test. If you change
 992                                          * it update the test too.
 993                                          */
 994                                         output(3, "Skipped %s (merged same as existing)", ren1_dst);
 995                                 else {
 996                                         if (mfi.merge || !mfi.clean)
 997                                                 output(1, "Renamed %s => %s", ren1_src, ren1_dst);
 998                                         if (mfi.merge)
 999                                                 output(2, "Auto-merged %s", ren1_dst);
1000                                         if (!mfi.clean) {
1001                                                 output(1, "CONFLICT (rename/modify): Merge conflict in %s",
1002                                                        ren1_dst);
1003                                                 clean_merge = 0;
1004
1005                                                 if (!index_only)
1006                                                         update_stages(ren1_dst,
1007                                                                       o, a, b, 1);
1008                                         }
1009                                         update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1010                                 }
1011                         }
1012                 }
1013         }
1014         path_list_clear(&a_by_dst, 0);
1015         path_list_clear(&b_by_dst, 0);
1016
1017         return clean_merge;
1018 }
1019
1020 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1021 {
1022         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1023 }
1024
1025 /* Per entry merge function */
1026 static int process_entry(const char *path, struct stage_data *entry,
1027                          const char *branch1,
1028                          const char *branch2)
1029 {
1030         /*
1031         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1032         print_index_entry("\tpath: ", entry);
1033         */
1034         int clean_merge = 1;
1035         unsigned o_mode = entry->stages[1].mode;
1036         unsigned a_mode = entry->stages[2].mode;
1037         unsigned b_mode = entry->stages[3].mode;
1038         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1039         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1040         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1041
1042         if (o_sha && (!a_sha || !b_sha)) {
1043                 /* Case A: Deleted in one */
1044                 if ((!a_sha && !b_sha) ||
1045                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1046                     (!a_sha && sha_eq(b_sha, o_sha))) {
1047                         /* Deleted in both or deleted in one and
1048                          * unchanged in the other */
1049                         if (a_sha)
1050                                 output(2, "Removed %s", path);
1051                         /* do not touch working file if it did not exist */
1052                         remove_file(1, path, !a_sha);
1053                 } else {
1054                         /* Deleted in one and changed in the other */
1055                         clean_merge = 0;
1056                         if (!a_sha) {
1057                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1058                                        "and modified in %s. Version %s of %s left in tree.",
1059                                        path, branch1,
1060                                        branch2, branch2, path);
1061                                 update_file(0, b_sha, b_mode, path);
1062                         } else {
1063                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1064                                        "and modified in %s. Version %s of %s left in tree.",
1065                                        path, branch2,
1066                                        branch1, branch1, path);
1067                                 update_file(0, a_sha, a_mode, path);
1068                         }
1069                 }
1070
1071         } else if ((!o_sha && a_sha && !b_sha) ||
1072                    (!o_sha && !a_sha && b_sha)) {
1073                 /* Case B: Added in one. */
1074                 const char *add_branch;
1075                 const char *other_branch;
1076                 unsigned mode;
1077                 const unsigned char *sha;
1078                 const char *conf;
1079
1080                 if (a_sha) {
1081                         add_branch = branch1;
1082                         other_branch = branch2;
1083                         mode = a_mode;
1084                         sha = a_sha;
1085                         conf = "file/directory";
1086                 } else {
1087                         add_branch = branch2;
1088                         other_branch = branch1;
1089                         mode = b_mode;
1090                         sha = b_sha;
1091                         conf = "directory/file";
1092                 }
1093                 if (path_list_has_path(&current_directory_set, path)) {
1094                         const char *new_path = unique_path(path, add_branch);
1095                         clean_merge = 0;
1096                         output(1, "CONFLICT (%s): There is a directory with name %s in %s. "
1097                                "Added %s as %s",
1098                                conf, path, other_branch, path, new_path);
1099                         remove_file(0, path, 0);
1100                         update_file(0, sha, mode, new_path);
1101                 } else {
1102                         output(2, "Added %s", path);
1103                         update_file(1, sha, mode, path);
1104                 }
1105         } else if (a_sha && b_sha) {
1106                 /* Case C: Added in both (check for same permissions) and */
1107                 /* case D: Modified in both, but differently. */
1108                 const char *reason = "content";
1109                 struct merge_file_info mfi;
1110                 struct diff_filespec o, a, b;
1111
1112                 if (!o_sha) {
1113                         reason = "add/add";
1114                         o_sha = (unsigned char *)null_sha1;
1115                 }
1116                 output(2, "Auto-merged %s", path);
1117                 o.path = a.path = b.path = (char *)path;
1118                 hashcpy(o.sha1, o_sha);
1119                 o.mode = o_mode;
1120                 hashcpy(a.sha1, a_sha);
1121                 a.mode = a_mode;
1122                 hashcpy(b.sha1, b_sha);
1123                 b.mode = b_mode;
1124
1125                 mfi = merge_file(&o, &a, &b,
1126                                  branch1, branch2);
1127
1128                 clean_merge = mfi.clean;
1129                 if (mfi.clean)
1130                         update_file(1, mfi.sha, mfi.mode, path);
1131                 else if (S_ISGITLINK(mfi.mode))
1132                         output(1, "CONFLICT (submodule): Merge conflict in %s "
1133                                "- needs %s", path, sha1_to_hex(b.sha1));
1134                 else {
1135                         output(1, "CONFLICT (%s): Merge conflict in %s",
1136                                         reason, path);
1137
1138                         if (index_only)
1139                                 update_file(0, mfi.sha, mfi.mode, path);
1140                         else
1141                                 update_file_flags(mfi.sha, mfi.mode, path,
1142                                               0 /* update_cache */, 1 /* update_working_directory */);
1143                 }
1144         } else if (!o_sha && !a_sha && !b_sha) {
1145                 /*
1146                  * this entry was deleted altogether. a_mode == 0 means
1147                  * we had that path and want to actively remove it.
1148                  */
1149                 remove_file(1, path, !a_mode);
1150         } else
1151                 die("Fatal merge failure, shouldn't happen.");
1152
1153         return clean_merge;
1154 }
1155
1156 int merge_trees(struct tree *head,
1157                 struct tree *merge,
1158                 struct tree *common,
1159                 const char *branch1,
1160                 const char *branch2,
1161                 struct tree **result)
1162 {
1163         int code, clean;
1164
1165         if (subtree_merge) {
1166                 merge = shift_tree_object(head, merge);
1167                 common = shift_tree_object(head, common);
1168         }
1169
1170         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1171                 output(0, "Already uptodate!");
1172                 *result = head;
1173                 return 1;
1174         }
1175
1176         code = git_merge_trees(index_only, common, head, merge);
1177
1178         if (code != 0)
1179                 die("merging of trees %s and %s failed",
1180                     sha1_to_hex(head->object.sha1),
1181                     sha1_to_hex(merge->object.sha1));
1182
1183         if (unmerged_cache()) {
1184                 struct path_list *entries, *re_head, *re_merge;
1185                 int i;
1186                 path_list_clear(&current_file_set, 1);
1187                 path_list_clear(&current_directory_set, 1);
1188                 get_files_dirs(head);
1189                 get_files_dirs(merge);
1190
1191                 entries = get_unmerged();
1192                 re_head  = get_renames(head, common, head, merge, entries);
1193                 re_merge = get_renames(merge, common, head, merge, entries);
1194                 clean = process_renames(re_head, re_merge,
1195                                 branch1, branch2);
1196                 for (i = 0; i < entries->nr; i++) {
1197                         const char *path = entries->items[i].path;
1198                         struct stage_data *e = entries->items[i].util;
1199                         if (!e->processed
1200                                 && !process_entry(path, e, branch1, branch2))
1201                                 clean = 0;
1202                 }
1203
1204                 path_list_clear(re_merge, 0);
1205                 path_list_clear(re_head, 0);
1206                 path_list_clear(entries, 1);
1207
1208         }
1209         else
1210                 clean = 1;
1211
1212         if (index_only)
1213                 *result = write_tree_from_memory();
1214
1215         return clean;
1216 }
1217
1218 static struct commit_list *reverse_commit_list(struct commit_list *list)
1219 {
1220         struct commit_list *next = NULL, *current, *backup;
1221         for (current = list; current; current = backup) {
1222                 backup = current->next;
1223                 current->next = next;
1224                 next = current;
1225         }
1226         return next;
1227 }
1228
1229 /*
1230  * Merge the commits h1 and h2, return the resulting virtual
1231  * commit object and a flag indicating the cleanness of the merge.
1232  */
1233 int merge_recursive(struct commit *h1,
1234                     struct commit *h2,
1235                     const char *branch1,
1236                     const char *branch2,
1237                     struct commit_list *ca,
1238                     struct commit **result)
1239 {
1240         struct commit_list *iter;
1241         struct commit *merged_common_ancestors;
1242         struct tree *mrtree = mrtree;
1243         int clean;
1244
1245         if (show(4)) {
1246                 output(4, "Merging:");
1247                 output_commit_title(h1);
1248                 output_commit_title(h2);
1249         }
1250
1251         if (!ca) {
1252                 ca = get_merge_bases(h1, h2, 1);
1253                 ca = reverse_commit_list(ca);
1254         }
1255
1256         if (show(5)) {
1257                 output(5, "found %u common ancestor(s):", commit_list_count(ca));
1258                 for (iter = ca; iter; iter = iter->next)
1259                         output_commit_title(iter->item);
1260         }
1261
1262         merged_common_ancestors = pop_commit(&ca);
1263         if (merged_common_ancestors == NULL) {
1264                 /* if there is no common ancestor, make an empty tree */
1265                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1266
1267                 tree->object.parsed = 1;
1268                 tree->object.type = OBJ_TREE;
1269                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1270                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1271         }
1272
1273         for (iter = ca; iter; iter = iter->next) {
1274                 call_depth++;
1275                 /*
1276                  * When the merge fails, the result contains files
1277                  * with conflict markers. The cleanness flag is
1278                  * ignored, it was never actually used, as result of
1279                  * merge_trees has always overwritten it: the committed
1280                  * "conflicts" were already resolved.
1281                  */
1282                 discard_cache();
1283                 merge_recursive(merged_common_ancestors, iter->item,
1284                                 "Temporary merge branch 1",
1285                                 "Temporary merge branch 2",
1286                                 NULL,
1287                                 &merged_common_ancestors);
1288                 call_depth--;
1289
1290                 if (!merged_common_ancestors)
1291                         die("merge returned no commit");
1292         }
1293
1294         discard_cache();
1295         if (!call_depth) {
1296                 read_cache();
1297                 index_only = 0;
1298         } else
1299                 index_only = 1;
1300
1301         clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
1302                             branch1, branch2, &mrtree);
1303
1304         if (index_only) {
1305                 *result = make_virtual_commit(mrtree, "merged tree");
1306                 commit_list_insert(h1, &(*result)->parents);
1307                 commit_list_insert(h2, &(*result)->parents->next);
1308         }
1309         flush_output();
1310         return clean;
1311 }
1312
1313 static const char *better_branch_name(const char *branch)
1314 {
1315         static char githead_env[8 + 40 + 1];
1316         char *name;
1317
1318         if (strlen(branch) != 40)
1319                 return branch;
1320         sprintf(githead_env, "GITHEAD_%s", branch);
1321         name = getenv(githead_env);
1322         return name ? name : branch;
1323 }
1324
1325 static struct commit *get_ref(const char *ref)
1326 {
1327         unsigned char sha1[20];
1328         struct object *object;
1329
1330         if (get_sha1(ref, sha1))
1331                 die("Could not resolve ref '%s'", ref);
1332         object = deref_tag(parse_object(sha1), ref, strlen(ref));
1333         if (!object)
1334                 return NULL;
1335         if (object->type == OBJ_TREE)
1336                 return make_virtual_commit((struct tree*)object,
1337                         better_branch_name(ref));
1338         if (object->type != OBJ_COMMIT)
1339                 return NULL;
1340         if (parse_commit((struct commit *)object))
1341                 die("Could not parse commit '%s'", sha1_to_hex(object->sha1));
1342         return (struct commit *)object;
1343 }
1344
1345 static int merge_config(const char *var, const char *value, void *cb)
1346 {
1347         if (!strcasecmp(var, "merge.verbosity")) {
1348                 verbosity = git_config_int(var, value);
1349                 return 0;
1350         }
1351         if (!strcasecmp(var, "diff.renamelimit")) {
1352                 diff_rename_limit = git_config_int(var, value);
1353                 return 0;
1354         }
1355         if (!strcasecmp(var, "merge.renamelimit")) {
1356                 merge_rename_limit = git_config_int(var, value);
1357                 return 0;
1358         }
1359         return git_default_config(var, value, cb);
1360 }
1361
1362 int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
1363 {
1364         static const char *bases[20];
1365         static unsigned bases_count = 0;
1366         int i, clean;
1367         const char *branch1, *branch2;
1368         struct commit *result, *h1, *h2;
1369         struct commit_list *ca = NULL;
1370         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1371         int index_fd;
1372
1373         if (argv[0]) {
1374                 int namelen = strlen(argv[0]);
1375                 if (8 < namelen &&
1376                     !strcmp(argv[0] + namelen - 8, "-subtree"))
1377                         subtree_merge = 1;
1378         }
1379
1380         git_config(merge_config, NULL);
1381         if (getenv("GIT_MERGE_VERBOSITY"))
1382                 verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1383
1384         if (argc < 4)
1385                 die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
1386
1387         for (i = 1; i < argc; ++i) {
1388                 if (!strcmp(argv[i], "--"))
1389                         break;
1390                 if (bases_count < sizeof(bases)/sizeof(*bases))
1391                         bases[bases_count++] = argv[i];
1392         }
1393         if (argc - i != 3) /* "--" "<head>" "<remote>" */
1394                 die("Not handling anything other than two heads merge.");
1395         if (verbosity >= 5)
1396                 buffer_output = 0;
1397
1398         branch1 = argv[++i];
1399         branch2 = argv[++i];
1400
1401         h1 = get_ref(branch1);
1402         h2 = get_ref(branch2);
1403
1404         branch1 = better_branch_name(branch1);
1405         branch2 = better_branch_name(branch2);
1406
1407         if (show(3))
1408                 printf("Merging %s with %s\n", branch1, branch2);
1409
1410         index_fd = hold_locked_index(lock, 1);
1411
1412         for (i = 0; i < bases_count; i++) {
1413                 struct commit *ancestor = get_ref(bases[i]);
1414                 ca = commit_list_insert(ancestor, &ca);
1415         }
1416         clean = merge_recursive(h1, h2, branch1, branch2, ca, &result);
1417
1418         if (active_cache_changed &&
1419             (write_cache(index_fd, active_cache, active_nr) ||
1420              commit_locked_index(lock)))
1421                         die ("unable to write %s", get_index_file());
1422
1423         return clean ? 0: 1;
1424 }