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.output_format = DIFF_FORMAT_NO_OUTPUT;
 369         if (diff_setup_done(&opts) < 0)
 370                 die("diff setup failed");
 371         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 372         diffcore_std(&opts);
 373         for (i = 0; i < diff_queued_diff.nr; ++i) {
 374                 struct path_list_item *item;
 375                 struct rename *re;
 376                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 377                 if (pair->status != 'R') {
 378                         diff_free_filepair(pair);
 379                         continue;
 380                 }
 381                 re = xmalloc(sizeof(*re));
 382                 re->processed = 0;
 383                 re->pair = pair;
 384                 item = path_list_lookup(re->pair->one->path, entries);
 385                 if (!item)
 386                         re->src_entry = insert_stage_data(re->pair->one->path,
 387                                         o_tree, a_tree, b_tree, entries);
 388                 else
 389                         re->src_entry = item->util;
 390
 391                 item = path_list_lookup(re->pair->two->path, entries);
 392                 if (!item)
 393                         re->dst_entry = insert_stage_data(re->pair->two->path,
 394                                         o_tree, a_tree, b_tree, entries);
 395                 else
 396                         re->dst_entry = item->util;
 397                 item = path_list_insert(pair->one->path, renames);
 398                 item->util = re;
 399         }
 400         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 401         diff_queued_diff.nr = 0;
 402         diff_flush(&opts);
 403         return renames;
 404 }
 405
 406 static int update_stages(const char *path, struct diff_filespec *o,
 407                          struct diff_filespec *a, struct diff_filespec *b,
 408                          int clear)
 409 {
 410         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 411         if (clear)
 412                 if (remove_file_from_cache(path))
 413                         return -1;
 414         if (o)
 415                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 416                         return -1;
 417         if (a)
 418                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 419                         return -1;
 420         if (b)
 421                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 422                         return -1;
 423         return 0;
 424 }
 425
 426 static int remove_path(const char *name)
 427 {
 428         int ret;
 429         char *slash, *dirs;
 430
 431         ret = unlink(name);
 432         if (ret)
 433                 return ret;
 434         dirs = xstrdup(name);
 435         while ((slash = strrchr(name, '/'))) {
 436                 *slash = '\0';
 437                 if (rmdir(name) != 0)
 438                         break;
 439         }
 440         free(dirs);
 441         return ret;
 442 }
 443
 444 static int remove_file(int clean, const char *path, int no_wd)
 445 {
 446         int update_cache = index_only || clean;
 447         int update_working_directory = !index_only && !no_wd;
 448
 449         if (update_cache) {
 450                 if (remove_file_from_cache(path))
 451                         return -1;
 452         }
 453         if (update_working_directory) {
 454                 unlink(path);
 455                 if (errno != ENOENT || errno != EISDIR)
 456                         return -1;
 457                 remove_path(path);
 458         }
 459         return 0;
 460 }
 461
 462 static char *unique_path(const char *path, const char *branch)
 463 {
 464         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 465         int suffix = 0;
 466         struct stat st;
 467         char *p = newpath + strlen(path);
 468         strcpy(newpath, path);
 469         *(p++) = '~';
 470         strcpy(p, branch);
 471         for (; *p; ++p)
 472                 if ('/' == *p)
 473                         *p = '_';
 474         while (path_list_has_path(&current_file_set, newpath) ||
 475                path_list_has_path(&current_directory_set, newpath) ||
 476                lstat(newpath, &st) == 0)
 477                 sprintf(p, "_%d", suffix++);
 478
 479         path_list_insert(newpath, &current_file_set);
 480         return newpath;
 481 }
 482
 483 static int mkdir_p(const char *path, unsigned long mode)
 484 {
 485         /* path points to cache entries, so xstrdup before messing with it */
 486         char *buf = xstrdup(path);
 487         int result = safe_create_leading_directories(buf);
 488         free(buf);
 489         return result;
 490 }
 491
 492 static void flush_buffer(int fd, const char *buf, unsigned long size)
 493 {
 494         while (size > 0) {
 495                 long ret = write_in_full(fd, buf, size);
 496                 if (ret < 0) {
 497                         /* Ignore epipe */
 498                         if (errno == EPIPE)
 499                                 break;
 500                         die("merge-recursive: %s", strerror(errno));
 501                 } else if (!ret) {
 502                         die("merge-recursive: disk full?");
 503                 }
 504                 size -= ret;
 505                 buf += ret;
 506         }
 507 }
 508
 509 static int make_room_for_path(const char *path)
 510 {
 511         int status;
 512         const char *msg = "failed to create path '%s'%s";
 513
 514         status = mkdir_p(path, 0777);
 515         if (status) {
 516                 if (status == -3) {
 517                         /* something else exists */
 518                         error(msg, path, ": perhaps a D/F conflict?");
 519                         return -1;
 520                 }
 521                 die(msg, path, "");
 522         }
 523
 524         /* Successful unlink is good.. */
 525         if (!unlink(path))
 526                 return 0;
 527         /* .. and so is no existing file */
 528         if (errno == ENOENT)
 529                 return 0;
 530         /* .. but not some other error (who really cares what?) */
 531         return error(msg, path, ": perhaps a D/F conflict?");
 532 }
 533
 534 static void update_file_flags(const unsigned char *sha,
 535                               unsigned mode,
 536                               const char *path,
 537                               int update_cache,
 538                               int update_wd)
 539 {
 540         if (index_only)
 541                 update_wd = 0;
 542
 543         if (update_wd) {
 544                 enum object_type type;
 545                 void *buf;
 546                 unsigned long size;
 547
 548                 if (S_ISGITLINK(mode))
 549                         die("cannot read object %s '%s': It is a submodule!",
 550                             sha1_to_hex(sha), path);
 551
 552                 buf = read_sha1_file(sha, &type, &size);
 553                 if (!buf)
 554                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 555                 if (type != OBJ_BLOB)
 556                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 557
 558                 if (make_room_for_path(path) < 0) {
 559                         update_wd = 0;
 560                         goto update_index;
 561                 }
 562                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 563                         int fd;
 564                         if (mode & 0100)
 565                                 mode = 0777;
 566                         else
 567                                 mode = 0666;
 568                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 569                         if (fd < 0)
 570                                 die("failed to open %s: %s", path, strerror(errno));
 571                         flush_buffer(fd, buf, size);
 572                         close(fd);
 573                 } else if (S_ISLNK(mode)) {
 574                         char *lnk = xmemdupz(buf, size);
 575                         mkdir_p(path, 0777);
 576                         unlink(path);
 577                         symlink(lnk, path);
 578                         free(lnk);
 579                 } else
 580                         die("do not know what to do with %06o %s '%s'",
 581                             mode, sha1_to_hex(sha), path);
 582         }
 583  update_index:
 584         if (update_cache)
 585                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 586 }
 587
 588 static void update_file(int clean,
 589                         const unsigned char *sha,
 590                         unsigned mode,
 591                         const char *path)
 592 {
 593         update_file_flags(sha, mode, path, index_only || clean, !index_only);
 594 }
 595
 596 /* Low level file merging, update and removal */
 597
 598 struct merge_file_info
 599 {
 600         unsigned char sha[20];
 601         unsigned mode;
 602         unsigned clean:1,
 603                  merge:1;
 604 };
 605
 606 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 607 {
 608         unsigned long size;
 609         enum object_type type;
 610
 611         if (!hashcmp(sha1, null_sha1)) {
 612                 mm->ptr = xstrdup("");
 613                 mm->size = 0;
 614                 return;
 615         }
 616
 617         mm->ptr = read_sha1_file(sha1, &type, &size);
 618         if (!mm->ptr || type != OBJ_BLOB)
 619                 die("unable to read blob object %s", sha1_to_hex(sha1));
 620         mm->size = size;
 621 }
 622
 623 static int merge_3way(mmbuffer_t *result_buf,
 624                       struct diff_filespec *o,
 625                       struct diff_filespec *a,
 626                       struct diff_filespec *b,
 627                       const char *branch1,
 628                       const char *branch2)
 629 {
 630         mmfile_t orig, src1, src2;
 631         char *name1, *name2;
 632         int merge_status;
 633
 634         name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 635         name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 636
 637         fill_mm(o->sha1, &orig);
 638         fill_mm(a->sha1, &src1);
 639         fill_mm(b->sha1, &src2);
 640
 641         merge_status = ll_merge(result_buf, a->path, &orig,
 642                                 &src1, name1, &src2, name2,
 643                                 index_only);
 644
 645         free(name1);
 646         free(name2);
 647         free(orig.ptr);
 648         free(src1.ptr);
 649         free(src2.ptr);
 650         return merge_status;
 651 }
 652
 653 static struct merge_file_info merge_file(struct diff_filespec *o,
 654                 struct diff_filespec *a, struct diff_filespec *b,
 655                 const char *branch1, const char *branch2)
 656 {
 657         struct merge_file_info result;
 658         result.merge = 0;
 659         result.clean = 1;
 660
 661         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 662                 result.clean = 0;
 663                 if (S_ISREG(a->mode)) {
 664                         result.mode = a->mode;
 665                         hashcpy(result.sha, a->sha1);
 666                 } else {
 667                         result.mode = b->mode;
 668                         hashcpy(result.sha, b->sha1);
 669                 }
 670         } else {
 671                 if (!sha_eq(a->sha1, o->sha1) && !sha_eq(b->sha1, o->sha1))
 672                         result.merge = 1;
 673
 674                 /*
 675                  * Merge modes
 676                  */
 677                 if (a->mode == b->mode || a->mode == o->mode)
 678                         result.mode = b->mode;
 679                 else {
 680                         result.mode = a->mode;
 681                         if (b->mode != o->mode) {
 682                                 result.clean = 0;
 683                                 result.merge = 1;
 684                         }
 685                 }
 686
 687                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, o->sha1))
 688                         hashcpy(result.sha, b->sha1);
 689                 else if (sha_eq(b->sha1, o->sha1))
 690                         hashcpy(result.sha, a->sha1);
 691                 else if (S_ISREG(a->mode)) {
 692                         mmbuffer_t result_buf;
 693                         int merge_status;
 694
 695                         merge_status = merge_3way(&result_buf, o, a, b,
 696                                                   branch1, branch2);
 697
 698                         if ((merge_status < 0) || !result_buf.ptr)
 699                                 die("Failed to execute internal merge");
 700
 701                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 702                                             blob_type, result.sha))
 703                                 die("Unable to add %s to database",
 704                                     a->path);
 705
 706                         free(result_buf.ptr);
 707                         result.clean = (merge_status == 0);
 708                 } else if (S_ISGITLINK(a->mode)) {
 709                         result.clean = 0;
 710                         hashcpy(result.sha, a->sha1);
 711                 } else if (S_ISLNK(a->mode)) {
 712                         hashcpy(result.sha, a->sha1);
 713
 714                         if (!sha_eq(a->sha1, b->sha1))
 715                                 result.clean = 0;
 716                 } else {
 717                         die("unsupported object type in the tree");
 718                 }
 719         }
 720
 721         return result;
 722 }
 723
 724 static void conflict_rename_rename(struct rename *ren1,
 725                                    const char *branch1,
 726                                    struct rename *ren2,
 727                                    const char *branch2)
 728 {
 729         char *del[2];
 730         int delp = 0;
 731         const char *ren1_dst = ren1->pair->two->path;
 732         const char *ren2_dst = ren2->pair->two->path;
 733         const char *dst_name1 = ren1_dst;
 734         const char *dst_name2 = ren2_dst;
 735         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 736                 dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
 737                 output(1, "%s is a directory in %s added as %s instead",
 738                        ren1_dst, branch2, dst_name1);
 739                 remove_file(0, ren1_dst, 0);
 740         }
 741         if (path_list_has_path(&current_directory_set, ren2_dst)) {
 742                 dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
 743                 output(1, "%s is a directory in %s added as %s instead",
 744                        ren2_dst, branch1, dst_name2);
 745                 remove_file(0, ren2_dst, 0);
 746         }
 747         if (index_only) {
 748                 remove_file_from_cache(dst_name1);
 749                 remove_file_from_cache(dst_name2);
 750                 /*
 751                  * Uncomment to leave the conflicting names in the resulting tree
 752                  *
 753                  * update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
 754                  * update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
 755                  */
 756         } else {
 757                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
 758                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
 759         }
 760         while (delp--)
 761                 free(del[delp]);
 762 }
 763
 764 static void conflict_rename_dir(struct rename *ren1,
 765                                 const char *branch1)
 766 {
 767         char *new_path = unique_path(ren1->pair->two->path, branch1);
 768         output(1, "Renamed %s to %s instead", ren1->pair->one->path, new_path);
 769         remove_file(0, ren1->pair->two->path, 0);
 770         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
 771         free(new_path);
 772 }
 773
 774 static void conflict_rename_rename_2(struct rename *ren1,
 775                                      const char *branch1,
 776                                      struct rename *ren2,
 777                                      const char *branch2)
 778 {
 779         char *new_path1 = unique_path(ren1->pair->two->path, branch1);
 780         char *new_path2 = unique_path(ren2->pair->two->path, branch2);
 781         output(1, "Renamed %s to %s and %s to %s instead",
 782                ren1->pair->one->path, new_path1,
 783                ren2->pair->one->path, new_path2);
 784         remove_file(0, ren1->pair->two->path, 0);
 785         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 786         update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 787         free(new_path2);
 788         free(new_path1);
 789 }
 790
 791 static int process_renames(struct path_list *a_renames,
 792                            struct path_list *b_renames,
 793                            const char *a_branch,
 794                            const char *b_branch)
 795 {
 796         int clean_merge = 1, i, j;
 797         struct path_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
 798         const struct rename *sre;
 799
 800         for (i = 0; i < a_renames->nr; i++) {
 801                 sre = a_renames->items[i].util;
 802                 path_list_insert(sre->pair->two->path, &a_by_dst)->util
 803                         = sre->dst_entry;
 804         }
 805         for (i = 0; i < b_renames->nr; i++) {
 806                 sre = b_renames->items[i].util;
 807                 path_list_insert(sre->pair->two->path, &b_by_dst)->util
 808                         = sre->dst_entry;
 809         }
 810
 811         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 812                 int compare;
 813                 char *src;
 814                 struct path_list *renames1, *renames2, *renames2Dst;
 815                 struct rename *ren1 = NULL, *ren2 = NULL;
 816                 const char *branch1, *branch2;
 817                 const char *ren1_src, *ren1_dst;
 818
 819                 if (i >= a_renames->nr) {
 820                         compare = 1;
 821                         ren2 = b_renames->items[j++].util;
 822                 } else if (j >= b_renames->nr) {
 823                         compare = -1;
 824                         ren1 = a_renames->items[i++].util;
 825                 } else {
 826                         compare = strcmp(a_renames->items[i].path,
 827                                         b_renames->items[j].path);
 828                         if (compare <= 0)
 829                                 ren1 = a_renames->items[i++].util;
 830                         if (compare >= 0)
 831                                 ren2 = b_renames->items[j++].util;
 832                 }
 833
 834                 /* TODO: refactor, so that 1/2 are not needed */
 835                 if (ren1) {
 836                         renames1 = a_renames;
 837                         renames2 = b_renames;
 838                         renames2Dst = &b_by_dst;
 839                         branch1 = a_branch;
 840                         branch2 = b_branch;
 841                 } else {
 842                         struct rename *tmp;
 843                         renames1 = b_renames;
 844                         renames2 = a_renames;
 845                         renames2Dst = &a_by_dst;
 846                         branch1 = b_branch;
 847                         branch2 = a_branch;
 848                         tmp = ren2;
 849                         ren2 = ren1;
 850                         ren1 = tmp;
 851                 }
 852                 src = ren1->pair->one->path;
 853
 854                 ren1->dst_entry->processed = 1;
 855                 ren1->src_entry->processed = 1;
 856
 857                 if (ren1->processed)
 858                         continue;
 859                 ren1->processed = 1;
 860
 861                 ren1_src = ren1->pair->one->path;
 862                 ren1_dst = ren1->pair->two->path;
 863
 864                 if (ren2) {
 865                         const char *ren2_src = ren2->pair->one->path;
 866                         const char *ren2_dst = ren2->pair->two->path;
 867                         /* Renamed in 1 and renamed in 2 */
 868                         if (strcmp(ren1_src, ren2_src) != 0)
 869                                 die("ren1.src != ren2.src");
 870                         ren2->dst_entry->processed = 1;
 871                         ren2->processed = 1;
 872                         if (strcmp(ren1_dst, ren2_dst) != 0) {
 873                                 clean_merge = 0;
 874                                 output(1, "CONFLICT (rename/rename): "
 875                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
 876                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
 877                                        src, ren1_dst, branch1,
 878                                        src, ren2_dst, branch2,
 879                                        index_only ? " (left unresolved)": "");
 880                                 if (index_only) {
 881                                         remove_file_from_cache(src);
 882                                         update_file(0, ren1->pair->one->sha1,
 883                                                     ren1->pair->one->mode, src);
 884                                 }
 885                                 conflict_rename_rename(ren1, branch1, ren2, branch2);
 886                         } else {
 887                                 struct merge_file_info mfi;
 888                                 remove_file(1, ren1_src, 1);
 889                                 mfi = merge_file(ren1->pair->one,
 890                                                  ren1->pair->two,
 891                                                  ren2->pair->two,
 892                                                  branch1,
 893                                                  branch2);
 894                                 if (mfi.merge || !mfi.clean)
 895                                         output(1, "Renamed %s->%s", src, ren1_dst);
 896
 897                                 if (mfi.merge)
 898                                         output(2, "Auto-merged %s", ren1_dst);
 899
 900                                 if (!mfi.clean) {
 901                                         output(1, "CONFLICT (content): merge conflict in %s",
 902                                                ren1_dst);
 903                                         clean_merge = 0;
 904
 905                                         if (!index_only)
 906                                                 update_stages(ren1_dst,
 907                                                               ren1->pair->one,
 908                                                               ren1->pair->two,
 909                                                               ren2->pair->two,
 910                                                               1 /* clear */);
 911                                 }
 912                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 913                         }
 914                 } else {
 915                         /* Renamed in 1, maybe changed in 2 */
 916                         struct path_list_item *item;
 917                         /* we only use sha1 and mode of these */
 918                         struct diff_filespec src_other, dst_other;
 919                         int try_merge, stage = a_renames == renames1 ? 3: 2;
 920
 921                         remove_file(1, ren1_src, index_only || stage == 3);
 922
 923                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
 924                         src_other.mode = ren1->src_entry->stages[stage].mode;
 925                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
 926                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
 927
 928                         try_merge = 0;
 929
 930                         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 931                                 clean_merge = 0;
 932                                 output(1, "CONFLICT (rename/directory): Renamed %s->%s in %s "
 933                                        " directory %s added in %s",
 934                                        ren1_src, ren1_dst, branch1,
 935                                        ren1_dst, branch2);
 936                                 conflict_rename_dir(ren1, branch1);
 937                         } else if (sha_eq(src_other.sha1, null_sha1)) {
 938                                 clean_merge = 0;
 939                                 output(1, "CONFLICT (rename/delete): Renamed %s->%s in %s "
 940                                        "and deleted in %s",
 941                                        ren1_src, ren1_dst, branch1,
 942                                        branch2);
 943                                 update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
 944                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
 945                                 const char *new_path;
 946                                 clean_merge = 0;
 947                                 try_merge = 1;
 948                                 output(1, "CONFLICT (rename/add): Renamed %s->%s in %s. "
 949                                        "%s added in %s",
 950                                        ren1_src, ren1_dst, branch1,
 951                                        ren1_dst, branch2);
 952                                 new_path = unique_path(ren1_dst, branch2);
 953                                 output(1, "Added as %s instead", new_path);
 954                                 update_file(0, dst_other.sha1, dst_other.mode, new_path);
 955                         } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
 956                                 ren2 = item->util;
 957                                 clean_merge = 0;
 958                                 ren2->processed = 1;
 959                                 output(1, "CONFLICT (rename/rename): Renamed %s->%s in %s. "
 960                                        "Renamed %s->%s in %s",
 961                                        ren1_src, ren1_dst, branch1,
 962                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
 963                                 conflict_rename_rename_2(ren1, branch1, ren2, branch2);
 964                         } else
 965                                 try_merge = 1;
 966
 967                         if (try_merge) {
 968                                 struct diff_filespec *o, *a, *b;
 969                                 struct merge_file_info mfi;
 970                                 src_other.path = (char *)ren1_src;
 971
 972                                 o = ren1->pair->one;
 973                                 if (a_renames == renames1) {
 974                                         a = ren1->pair->two;
 975                                         b = &src_other;
 976                                 } else {
 977                                         b = ren1->pair->two;
 978                                         a = &src_other;
 979                                 }
 980                                 mfi = merge_file(o, a, b,
 981                                                 a_branch, b_branch);
 982
 983                                 if (mfi.clean &&
 984                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
 985                                     mfi.mode == ren1->pair->two->mode)
 986                                         /*
 987                                          * This messaged is part of
 988                                          * t6022 test. If you change
 989                                          * it update the test too.
 990                                          */
 991                                         output(3, "Skipped %s (merged same as existing)", ren1_dst);
 992                                 else {
 993                                         if (mfi.merge || !mfi.clean)
 994                                                 output(1, "Renamed %s => %s", ren1_src, ren1_dst);
 995                                         if (mfi.merge)
 996                                                 output(2, "Auto-merged %s", ren1_dst);
 997                                         if (!mfi.clean) {
 998                                                 output(1, "CONFLICT (rename/modify): Merge conflict in %s",
 999                                                        ren1_dst);
1000                                                 clean_merge = 0;
1001
1002                                                 if (!index_only)
1003                                                         update_stages(ren1_dst,
1004                                                                       o, a, b, 1);
1005                                         }
1006                                         update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1007                                 }
1008                         }
1009                 }
1010         }
1011         path_list_clear(&a_by_dst, 0);
1012         path_list_clear(&b_by_dst, 0);
1013
1014         return clean_merge;
1015 }
1016
1017 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1018 {
1019         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1020 }
1021
1022 /* Per entry merge function */
1023 static int process_entry(const char *path, struct stage_data *entry,
1024                          const char *branch1,
1025                          const char *branch2)
1026 {
1027         /*
1028         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1029         print_index_entry("\tpath: ", entry);
1030         */
1031         int clean_merge = 1;
1032         unsigned o_mode = entry->stages[1].mode;
1033         unsigned a_mode = entry->stages[2].mode;
1034         unsigned b_mode = entry->stages[3].mode;
1035         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1036         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1037         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1038
1039         if (o_sha && (!a_sha || !b_sha)) {
1040                 /* Case A: Deleted in one */
1041                 if ((!a_sha && !b_sha) ||
1042                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1043                     (!a_sha && sha_eq(b_sha, o_sha))) {
1044                         /* Deleted in both or deleted in one and
1045                          * unchanged in the other */
1046                         if (a_sha)
1047                                 output(2, "Removed %s", path);
1048                         /* do not touch working file if it did not exist */
1049                         remove_file(1, path, !a_sha);
1050                 } else {
1051                         /* Deleted in one and changed in the other */
1052                         clean_merge = 0;
1053                         if (!a_sha) {
1054                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1055                                        "and modified in %s. Version %s of %s left in tree.",
1056                                        path, branch1,
1057                                        branch2, branch2, path);
1058                                 update_file(0, b_sha, b_mode, path);
1059                         } else {
1060                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1061                                        "and modified in %s. Version %s of %s left in tree.",
1062                                        path, branch2,
1063                                        branch1, branch1, path);
1064                                 update_file(0, a_sha, a_mode, path);
1065                         }
1066                 }
1067
1068         } else if ((!o_sha && a_sha && !b_sha) ||
1069                    (!o_sha && !a_sha && b_sha)) {
1070                 /* Case B: Added in one. */
1071                 const char *add_branch;
1072                 const char *other_branch;
1073                 unsigned mode;
1074                 const unsigned char *sha;
1075                 const char *conf;
1076
1077                 if (a_sha) {
1078                         add_branch = branch1;
1079                         other_branch = branch2;
1080                         mode = a_mode;
1081                         sha = a_sha;
1082                         conf = "file/directory";
1083                 } else {
1084                         add_branch = branch2;
1085                         other_branch = branch1;
1086                         mode = b_mode;
1087                         sha = b_sha;
1088                         conf = "directory/file";
1089                 }
1090                 if (path_list_has_path(&current_directory_set, path)) {
1091                         const char *new_path = unique_path(path, add_branch);
1092                         clean_merge = 0;
1093                         output(1, "CONFLICT (%s): There is a directory with name %s in %s. "
1094                                "Added %s as %s",
1095                                conf, path, other_branch, path, new_path);
1096                         remove_file(0, path, 0);
1097                         update_file(0, sha, mode, new_path);
1098                 } else {
1099                         output(2, "Added %s", path);
1100                         update_file(1, sha, mode, path);
1101                 }
1102         } else if (a_sha && b_sha) {
1103                 /* Case C: Added in both (check for same permissions) and */
1104                 /* case D: Modified in both, but differently. */
1105                 const char *reason = "content";
1106                 struct merge_file_info mfi;
1107                 struct diff_filespec o, a, b;
1108
1109                 if (!o_sha) {
1110                         reason = "add/add";
1111                         o_sha = (unsigned char *)null_sha1;
1112                 }
1113                 output(2, "Auto-merged %s", path);
1114                 o.path = a.path = b.path = (char *)path;
1115                 hashcpy(o.sha1, o_sha);
1116                 o.mode = o_mode;
1117                 hashcpy(a.sha1, a_sha);
1118                 a.mode = a_mode;
1119                 hashcpy(b.sha1, b_sha);
1120                 b.mode = b_mode;
1121
1122                 mfi = merge_file(&o, &a, &b,
1123                                  branch1, branch2);
1124
1125                 clean_merge = mfi.clean;
1126                 if (mfi.clean)
1127                         update_file(1, mfi.sha, mfi.mode, path);
1128                 else if (S_ISGITLINK(mfi.mode))
1129                         output(1, "CONFLICT (submodule): Merge conflict in %s "
1130                                "- needs %s", path, sha1_to_hex(b.sha1));
1131                 else {
1132                         output(1, "CONFLICT (%s): Merge conflict in %s",
1133                                         reason, path);
1134
1135                         if (index_only)
1136                                 update_file(0, mfi.sha, mfi.mode, path);
1137                         else
1138                                 update_file_flags(mfi.sha, mfi.mode, path,
1139                                               0 /* update_cache */, 1 /* update_working_directory */);
1140                 }
1141         } else if (!o_sha && !a_sha && !b_sha) {
1142                 /*
1143                  * this entry was deleted altogether. a_mode == 0 means
1144                  * we had that path and want to actively remove it.
1145                  */
1146                 remove_file(1, path, !a_mode);
1147         } else
1148                 die("Fatal merge failure, shouldn't happen.");
1149
1150         return clean_merge;
1151 }
1152
1153 int merge_trees(struct tree *head,
1154                 struct tree *merge,
1155                 struct tree *common,
1156                 const char *branch1,
1157                 const char *branch2,
1158                 struct tree **result)
1159 {
1160         int code, clean;
1161
1162         if (subtree_merge) {
1163                 merge = shift_tree_object(head, merge);
1164                 common = shift_tree_object(head, common);
1165         }
1166
1167         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1168                 output(0, "Already uptodate!");
1169                 *result = head;
1170                 return 1;
1171         }
1172
1173         code = git_merge_trees(index_only, common, head, merge);
1174
1175         if (code != 0)
1176                 die("merging of trees %s and %s failed",
1177                     sha1_to_hex(head->object.sha1),
1178                     sha1_to_hex(merge->object.sha1));
1179
1180         if (unmerged_cache()) {
1181                 struct path_list *entries, *re_head, *re_merge;
1182                 int i;
1183                 path_list_clear(&current_file_set, 1);
1184                 path_list_clear(&current_directory_set, 1);
1185                 get_files_dirs(head);
1186                 get_files_dirs(merge);
1187
1188                 entries = get_unmerged();
1189                 re_head  = get_renames(head, common, head, merge, entries);
1190                 re_merge = get_renames(merge, common, head, merge, entries);
1191                 clean = process_renames(re_head, re_merge,
1192                                 branch1, branch2);
1193                 for (i = 0; i < entries->nr; i++) {
1194                         const char *path = entries->items[i].path;
1195                         struct stage_data *e = entries->items[i].util;
1196                         if (!e->processed
1197                                 && !process_entry(path, e, branch1, branch2))
1198                                 clean = 0;
1199                 }
1200
1201                 path_list_clear(re_merge, 0);
1202                 path_list_clear(re_head, 0);
1203                 path_list_clear(entries, 1);
1204
1205         }
1206         else
1207                 clean = 1;
1208
1209         if (index_only)
1210                 *result = write_tree_from_memory();
1211
1212         return clean;
1213 }
1214
1215 static struct commit_list *reverse_commit_list(struct commit_list *list)
1216 {
1217         struct commit_list *next = NULL, *current, *backup;
1218         for (current = list; current; current = backup) {
1219                 backup = current->next;
1220                 current->next = next;
1221                 next = current;
1222         }
1223         return next;
1224 }
1225
1226 /*
1227  * Merge the commits h1 and h2, return the resulting virtual
1228  * commit object and a flag indicating the cleanness of the merge.
1229  */
1230 int merge_recursive(struct commit *h1,
1231                     struct commit *h2,
1232                     const char *branch1,
1233                     const char *branch2,
1234                     struct commit_list *ca,
1235                     struct commit **result)
1236 {
1237         struct commit_list *iter;
1238         struct commit *merged_common_ancestors;
1239         struct tree *mrtree = mrtree;
1240         int clean;
1241
1242         if (show(4)) {
1243                 output(4, "Merging:");
1244                 output_commit_title(h1);
1245                 output_commit_title(h2);
1246         }
1247
1248         if (!ca) {
1249                 ca = get_merge_bases(h1, h2, 1);
1250                 ca = reverse_commit_list(ca);
1251         }
1252
1253         if (show(5)) {
1254                 output(5, "found %u common ancestor(s):", commit_list_count(ca));
1255                 for (iter = ca; iter; iter = iter->next)
1256                         output_commit_title(iter->item);
1257         }
1258
1259         merged_common_ancestors = pop_commit(&ca);
1260         if (merged_common_ancestors == NULL) {
1261                 /* if there is no common ancestor, make an empty tree */
1262                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1263
1264                 tree->object.parsed = 1;
1265                 tree->object.type = OBJ_TREE;
1266                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1267                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1268         }
1269
1270         for (iter = ca; iter; iter = iter->next) {
1271                 call_depth++;
1272                 /*
1273                  * When the merge fails, the result contains files
1274                  * with conflict markers. The cleanness flag is
1275                  * ignored, it was never actually used, as result of
1276                  * merge_trees has always overwritten it: the committed
1277                  * "conflicts" were already resolved.
1278                  */
1279                 discard_cache();
1280                 merge_recursive(merged_common_ancestors, iter->item,
1281                                 "Temporary merge branch 1",
1282                                 "Temporary merge branch 2",
1283                                 NULL,
1284                                 &merged_common_ancestors);
1285                 call_depth--;
1286
1287                 if (!merged_common_ancestors)
1288                         die("merge returned no commit");
1289         }
1290
1291         discard_cache();
1292         if (!call_depth) {
1293                 read_cache();
1294                 index_only = 0;
1295         } else
1296                 index_only = 1;
1297
1298         clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
1299                             branch1, branch2, &mrtree);
1300
1301         if (index_only) {
1302                 *result = make_virtual_commit(mrtree, "merged tree");
1303                 commit_list_insert(h1, &(*result)->parents);
1304                 commit_list_insert(h2, &(*result)->parents->next);
1305         }
1306         flush_output();
1307         return clean;
1308 }
1309
1310 static const char *better_branch_name(const char *branch)
1311 {
1312         static char githead_env[8 + 40 + 1];
1313         char *name;
1314
1315         if (strlen(branch) != 40)
1316                 return branch;
1317         sprintf(githead_env, "GITHEAD_%s", branch);
1318         name = getenv(githead_env);
1319         return name ? name : branch;
1320 }
1321
1322 static struct commit *get_ref(const char *ref)
1323 {
1324         unsigned char sha1[20];
1325         struct object *object;
1326
1327         if (get_sha1(ref, sha1))
1328                 die("Could not resolve ref '%s'", ref);
1329         object = deref_tag(parse_object(sha1), ref, strlen(ref));
1330         if (!object)
1331                 return NULL;
1332         if (object->type == OBJ_TREE)
1333                 return make_virtual_commit((struct tree*)object,
1334                         better_branch_name(ref));
1335         if (object->type != OBJ_COMMIT)
1336                 return NULL;
1337         if (parse_commit((struct commit *)object))
1338                 die("Could not parse commit '%s'", sha1_to_hex(object->sha1));
1339         return (struct commit *)object;
1340 }
1341
1342 static int merge_config(const char *var, const char *value)
1343 {
1344         if (!strcasecmp(var, "merge.verbosity")) {
1345                 verbosity = git_config_int(var, value);
1346                 return 0;
1347         }
1348         if (!strcasecmp(var, "diff.renamelimit")) {
1349                 diff_rename_limit = git_config_int(var, value);
1350                 return 0;
1351         }
1352         if (!strcasecmp(var, "merge.renamelimit")) {
1353                 merge_rename_limit = git_config_int(var, value);
1354                 return 0;
1355         }
1356         return git_default_config(var, value);
1357 }
1358
1359 int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
1360 {
1361         static const char *bases[20];
1362         static unsigned bases_count = 0;
1363         int i, clean;
1364         const char *branch1, *branch2;
1365         struct commit *result, *h1, *h2;
1366         struct commit_list *ca = NULL;
1367         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1368         int index_fd;
1369
1370         if (argv[0]) {
1371                 int namelen = strlen(argv[0]);
1372                 if (8 < namelen &&
1373                     !strcmp(argv[0] + namelen - 8, "-subtree"))
1374                         subtree_merge = 1;
1375         }
1376
1377         git_config(merge_config);
1378         if (getenv("GIT_MERGE_VERBOSITY"))
1379                 verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1380
1381         if (argc < 4)
1382                 die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
1383
1384         for (i = 1; i < argc; ++i) {
1385                 if (!strcmp(argv[i], "--"))
1386                         break;
1387                 if (bases_count < sizeof(bases)/sizeof(*bases))
1388                         bases[bases_count++] = argv[i];
1389         }
1390         if (argc - i != 3) /* "--" "<head>" "<remote>" */
1391                 die("Not handling anything other than two heads merge.");
1392         if (verbosity >= 5)
1393                 buffer_output = 0;
1394
1395         branch1 = argv[++i];
1396         branch2 = argv[++i];
1397
1398         h1 = get_ref(branch1);
1399         h2 = get_ref(branch2);
1400
1401         branch1 = better_branch_name(branch1);
1402         branch2 = better_branch_name(branch2);
1403
1404         if (show(3))
1405                 printf("Merging %s with %s\n", branch1, branch2);
1406
1407         index_fd = hold_locked_index(lock, 1);
1408
1409         for (i = 0; i < bases_count; i++) {
1410                 struct commit *ancestor = get_ref(bases[i]);
1411                 ca = commit_list_insert(ancestor, &ca);
1412         }
1413         clean = merge_recursive(h1, h2, branch1, branch2, ca, &result);
1414
1415         if (active_cache_changed &&
1416             (write_cache(index_fd, active_cache, active_nr) ||
1417              commit_locked_index(lock)))
1418                         die ("unable to write %s", get_index_file());
1419
1420         return clean ? 0: 1;
1421 }