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 rename_limit = -1;
  96 static int buffer_output = 1;
  97 static struct strbuf obuf = STRBUF_INIT;
  98
  99 static int show(int v)
 100 {
 101         return (!call_depth && verbosity >= v) || verbosity >= 5;
 102 }
 103
 104 static void flush_output(void)
 105 {
 106         if (obuf.len) {
 107                 fputs(obuf.buf, stdout);
 108                 strbuf_reset(&obuf);
 109         }
 110 }
 111
 112 static void output(int v, const char *fmt, ...)
 113 {
 114         int len;
 115         va_list ap;
 116
 117         if (!show(v))
 118                 return;
 119
 120         strbuf_grow(&obuf, call_depth * 2 + 2);
 121         memset(obuf.buf + obuf.len, ' ', call_depth * 2);
 122         strbuf_setlen(&obuf, obuf.len + call_depth * 2);
 123
 124         va_start(ap, fmt);
 125         len = vsnprintf(obuf.buf + obuf.len, strbuf_avail(&obuf), fmt, ap);
 126         va_end(ap);
 127
 128         if (len < 0)
 129                 len = 0;
 130         if (len >= strbuf_avail(&obuf)) {
 131                 strbuf_grow(&obuf, len + 2);
 132                 va_start(ap, fmt);
 133                 len = vsnprintf(obuf.buf + obuf.len, strbuf_avail(&obuf), fmt, ap);
 134                 va_end(ap);
 135                 if (len >= strbuf_avail(&obuf)) {
 136                         die("this should not happen, your snprintf is broken");
 137                 }
 138         }
 139         strbuf_setlen(&obuf, obuf.len + len);
 140         strbuf_add(&obuf, "\n", 1);
 141         if (!buffer_output)
 142                 flush_output();
 143 }
 144
 145 static void output_commit_title(struct commit *commit)
 146 {
 147         int i;
 148         flush_output();
 149         for (i = call_depth; i--;)
 150                 fputs("  ", stdout);
 151         if (commit->util)
 152                 printf("virtual %s\n", (char *)commit->util);
 153         else {
 154                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 155                 if (parse_commit(commit) != 0)
 156                         printf("(bad commit)\n");
 157                 else {
 158                         const char *s;
 159                         int len;
 160                         for (s = commit->buffer; *s; s++)
 161                                 if (*s == '\n' && s[1] == '\n') {
 162                                         s += 2;
 163                                         break;
 164                                 }
 165                         for (len = 0; s[len] && '\n' != s[len]; len++)
 166                                 ; /* do nothing */
 167                         printf("%.*s\n", len, s);
 168                 }
 169         }
 170 }
 171
 172 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 173                 const char *path, int stage, int refresh, int options)
 174 {
 175         struct cache_entry *ce;
 176         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 177         if (!ce)
 178                 return error("addinfo_cache failed for path '%s'", path);
 179         return add_cache_entry(ce, options);
 180 }
 181
 182 /*
 183  * This is a global variable which is used in a number of places but
 184  * only written to in the 'merge' function.
 185  *
 186  * index_only == 1    => Don't leave any non-stage 0 entries in the cache and
 187  *                       don't update the working directory.
 188  *               0    => Leave unmerged entries in the cache and update
 189  *                       the working directory.
 190  */
 191 static int index_only = 0;
 192
 193 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 194 {
 195         parse_tree(tree);
 196         init_tree_desc(desc, tree->buffer, tree->size);
 197 }
 198
 199 static int git_merge_trees(int index_only,
 200                            struct tree *common,
 201                            struct tree *head,
 202                            struct tree *merge)
 203 {
 204         int rc;
 205         struct tree_desc t[3];
 206         struct unpack_trees_options opts;
 207
 208         memset(&opts, 0, sizeof(opts));
 209         if (index_only)
 210                 opts.index_only = 1;
 211         else
 212                 opts.update = 1;
 213         opts.merge = 1;
 214         opts.head_idx = 2;
 215         opts.fn = threeway_merge;
 216         opts.src_index = &the_index;
 217         opts.dst_index = &the_index;
 218
 219         init_tree_desc_from_tree(t+0, common);
 220         init_tree_desc_from_tree(t+1, head);
 221         init_tree_desc_from_tree(t+2, merge);
 222
 223         rc = unpack_trees(3, t, &opts);
 224         cache_tree_free(&active_cache_tree);
 225         return rc;
 226 }
 227
 228 struct tree *write_tree_from_memory(void)
 229 {
 230         struct tree *result = NULL;
 231
 232         if (unmerged_cache()) {
 233                 int i;
 234                 output(0, "There are unmerged index entries:");
 235                 for (i = 0; i < active_nr; i++) {
 236                         struct cache_entry *ce = active_cache[i];
 237                         if (ce_stage(ce))
 238                                 output(0, "%d %.*s", ce_stage(ce), ce_namelen(ce), ce->name);
 239                 }
 240                 return NULL;
 241         }
 242
 243         if (!active_cache_tree)
 244                 active_cache_tree = cache_tree();
 245
 246         if (!cache_tree_fully_valid(active_cache_tree) &&
 247             cache_tree_update(active_cache_tree,
 248                               active_cache, active_nr, 0, 0) < 0)
 249                 die("error building trees");
 250
 251         result = lookup_tree(active_cache_tree->sha1);
 252
 253         return result;
 254 }
 255
 256 static int save_files_dirs(const unsigned char *sha1,
 257                 const char *base, int baselen, const char *path,
 258                 unsigned int mode, int stage)
 259 {
 260         int len = strlen(path);
 261         char *newpath = xmalloc(baselen + len + 1);
 262         memcpy(newpath, base, baselen);
 263         memcpy(newpath + baselen, path, len);
 264         newpath[baselen + len] = '\0';
 265
 266         if (S_ISDIR(mode))
 267                 path_list_insert(newpath, &current_directory_set);
 268         else
 269                 path_list_insert(newpath, &current_file_set);
 270         free(newpath);
 271
 272         return READ_TREE_RECURSIVE;
 273 }
 274
 275 static int get_files_dirs(struct tree *tree)
 276 {
 277         int n;
 278         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs) != 0)
 279                 return 0;
 280         n = current_file_set.nr + current_directory_set.nr;
 281         return n;
 282 }
 283
 284 /*
 285  * Returns an index_entry instance which doesn't have to correspond to
 286  * a real cache entry in Git's index.
 287  */
 288 static struct stage_data *insert_stage_data(const char *path,
 289                 struct tree *o, struct tree *a, struct tree *b,
 290                 struct path_list *entries)
 291 {
 292         struct path_list_item *item;
 293         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 294         get_tree_entry(o->object.sha1, path,
 295                         e->stages[1].sha, &e->stages[1].mode);
 296         get_tree_entry(a->object.sha1, path,
 297                         e->stages[2].sha, &e->stages[2].mode);
 298         get_tree_entry(b->object.sha1, path,
 299                         e->stages[3].sha, &e->stages[3].mode);
 300         item = path_list_insert(path, entries);
 301         item->util = e;
 302         return e;
 303 }
 304
 305 /*
 306  * Create a dictionary mapping file names to stage_data objects. The
 307  * dictionary contains one entry for every path with a non-zero stage entry.
 308  */
 309 static struct path_list *get_unmerged(void)
 310 {
 311         struct path_list *unmerged = xcalloc(1, sizeof(struct path_list));
 312         int i;
 313
 314         unmerged->strdup_paths = 1;
 315
 316         for (i = 0; i < active_nr; i++) {
 317                 struct path_list_item *item;
 318                 struct stage_data *e;
 319                 struct cache_entry *ce = active_cache[i];
 320                 if (!ce_stage(ce))
 321                         continue;
 322
 323                 item = path_list_lookup(ce->name, unmerged);
 324                 if (!item) {
 325                         item = path_list_insert(ce->name, unmerged);
 326                         item->util = xcalloc(1, sizeof(struct stage_data));
 327                 }
 328                 e = item->util;
 329                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
 330                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 331         }
 332
 333         return unmerged;
 334 }
 335
 336 struct rename
 337 {
 338         struct diff_filepair *pair;
 339         struct stage_data *src_entry;
 340         struct stage_data *dst_entry;
 341         unsigned processed:1;
 342 };
 343
 344 /*
 345  * Get information of all renames which occurred between 'o_tree' and
 346  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 347  * 'b_tree') to be able to associate the correct cache entries with
 348  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 349  */
 350 static struct path_list *get_renames(struct tree *tree,
 351                                         struct tree *o_tree,
 352                                         struct tree *a_tree,
 353                                         struct tree *b_tree,
 354                                         struct path_list *entries)
 355 {
 356         int i;
 357         struct path_list *renames;
 358         struct diff_options opts;
 359
 360         renames = xcalloc(1, sizeof(struct path_list));
 361         diff_setup(&opts);
 362         DIFF_OPT_SET(&opts, RECURSIVE);
 363         opts.detect_rename = DIFF_DETECT_RENAME;
 364         opts.rename_limit = rename_limit;
 365         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 366         if (diff_setup_done(&opts) < 0)
 367                 die("diff setup failed");
 368         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 369         diffcore_std(&opts);
 370         for (i = 0; i < diff_queued_diff.nr; ++i) {
 371                 struct path_list_item *item;
 372                 struct rename *re;
 373                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 374                 if (pair->status != 'R') {
 375                         diff_free_filepair(pair);
 376                         continue;
 377                 }
 378                 re = xmalloc(sizeof(*re));
 379                 re->processed = 0;
 380                 re->pair = pair;
 381                 item = path_list_lookup(re->pair->one->path, entries);
 382                 if (!item)
 383                         re->src_entry = insert_stage_data(re->pair->one->path,
 384                                         o_tree, a_tree, b_tree, entries);
 385                 else
 386                         re->src_entry = item->util;
 387
 388                 item = path_list_lookup(re->pair->two->path, entries);
 389                 if (!item)
 390                         re->dst_entry = insert_stage_data(re->pair->two->path,
 391                                         o_tree, a_tree, b_tree, entries);
 392                 else
 393                         re->dst_entry = item->util;
 394                 item = path_list_insert(pair->one->path, renames);
 395                 item->util = re;
 396         }
 397         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 398         diff_queued_diff.nr = 0;
 399         diff_flush(&opts);
 400         return renames;
 401 }
 402
 403 static int update_stages(const char *path, struct diff_filespec *o,
 404                          struct diff_filespec *a, struct diff_filespec *b,
 405                          int clear)
 406 {
 407         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 408         if (clear)
 409                 if (remove_file_from_cache(path))
 410                         return -1;
 411         if (o)
 412                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 413                         return -1;
 414         if (a)
 415                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 416                         return -1;
 417         if (b)
 418                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 419                         return -1;
 420         return 0;
 421 }
 422
 423 static int remove_path(const char *name)
 424 {
 425         int ret;
 426         char *slash, *dirs;
 427
 428         ret = unlink(name);
 429         if (ret)
 430                 return ret;
 431         dirs = xstrdup(name);
 432         while ((slash = strrchr(name, '/'))) {
 433                 *slash = '\0';
 434                 if (rmdir(name) != 0)
 435                         break;
 436         }
 437         free(dirs);
 438         return ret;
 439 }
 440
 441 static int remove_file(int clean, const char *path, int no_wd)
 442 {
 443         int update_cache = index_only || clean;
 444         int update_working_directory = !index_only && !no_wd;
 445
 446         if (update_cache) {
 447                 if (remove_file_from_cache(path))
 448                         return -1;
 449         }
 450         if (update_working_directory) {
 451                 unlink(path);
 452                 if (errno != ENOENT || errno != EISDIR)
 453                         return -1;
 454                 remove_path(path);
 455         }
 456         return 0;
 457 }
 458
 459 static char *unique_path(const char *path, const char *branch)
 460 {
 461         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 462         int suffix = 0;
 463         struct stat st;
 464         char *p = newpath + strlen(path);
 465         strcpy(newpath, path);
 466         *(p++) = '~';
 467         strcpy(p, branch);
 468         for (; *p; ++p)
 469                 if ('/' == *p)
 470                         *p = '_';
 471         while (path_list_has_path(&current_file_set, newpath) ||
 472                path_list_has_path(&current_directory_set, newpath) ||
 473                lstat(newpath, &st) == 0)
 474                 sprintf(p, "_%d", suffix++);
 475
 476         path_list_insert(newpath, &current_file_set);
 477         return newpath;
 478 }
 479
 480 static int mkdir_p(const char *path, unsigned long mode)
 481 {
 482         /* path points to cache entries, so xstrdup before messing with it */
 483         char *buf = xstrdup(path);
 484         int result = safe_create_leading_directories(buf);
 485         free(buf);
 486         return result;
 487 }
 488
 489 static void flush_buffer(int fd, const char *buf, unsigned long size)
 490 {
 491         while (size > 0) {
 492                 long ret = write_in_full(fd, buf, size);
 493                 if (ret < 0) {
 494                         /* Ignore epipe */
 495                         if (errno == EPIPE)
 496                                 break;
 497                         die("merge-recursive: %s", strerror(errno));
 498                 } else if (!ret) {
 499                         die("merge-recursive: disk full?");
 500                 }
 501                 size -= ret;
 502                 buf += ret;
 503         }
 504 }
 505
 506 static int make_room_for_path(const char *path)
 507 {
 508         int status;
 509         const char *msg = "failed to create path '%s'%s";
 510
 511         status = mkdir_p(path, 0777);
 512         if (status) {
 513                 if (status == -3) {
 514                         /* something else exists */
 515                         error(msg, path, ": perhaps a D/F conflict?");
 516                         return -1;
 517                 }
 518                 die(msg, path, "");
 519         }
 520
 521         /* Successful unlink is good.. */
 522         if (!unlink(path))
 523                 return 0;
 524         /* .. and so is no existing file */
 525         if (errno == ENOENT)
 526                 return 0;
 527         /* .. but not some other error (who really cares what?) */
 528         return error(msg, path, ": perhaps a D/F conflict?");
 529 }
 530
 531 static void update_file_flags(const unsigned char *sha,
 532                               unsigned mode,
 533                               const char *path,
 534                               int update_cache,
 535                               int update_wd)
 536 {
 537         if (index_only)
 538                 update_wd = 0;
 539
 540         if (update_wd) {
 541                 enum object_type type;
 542                 void *buf;
 543                 unsigned long size;
 544
 545                 if (S_ISGITLINK(mode))
 546                         die("cannot read object %s '%s': It is a submodule!",
 547                             sha1_to_hex(sha), path);
 548
 549                 buf = read_sha1_file(sha, &type, &size);
 550                 if (!buf)
 551                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 552                 if (type != OBJ_BLOB)
 553                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 554                 if (S_ISREG(mode)) {
 555                         struct strbuf strbuf;
 556                         strbuf_init(&strbuf, 0);
 557                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
 558                                 free(buf);
 559                                 size = strbuf.len;
 560                                 buf = strbuf_detach(&strbuf, NULL);
 561                         }
 562                 }
 563
 564                 if (make_room_for_path(path) < 0) {
 565                         update_wd = 0;
 566                         free(buf);
 567                         goto update_index;
 568                 }
 569                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 570                         int fd;
 571                         if (mode & 0100)
 572                                 mode = 0777;
 573                         else
 574                                 mode = 0666;
 575                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 576                         if (fd < 0)
 577                                 die("failed to open %s: %s", path, strerror(errno));
 578                         flush_buffer(fd, buf, size);
 579                         close(fd);
 580                 } else if (S_ISLNK(mode)) {
 581                         char *lnk = xmemdupz(buf, size);
 582                         mkdir_p(path, 0777);
 583                         unlink(path);
 584                         symlink(lnk, path);
 585                         free(lnk);
 586                 } else
 587                         die("do not know what to do with %06o %s '%s'",
 588                             mode, sha1_to_hex(sha), path);
 589                 free(buf);
 590         }
 591  update_index:
 592         if (update_cache)
 593                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 594 }
 595
 596 static void update_file(int clean,
 597                         const unsigned char *sha,
 598                         unsigned mode,
 599                         const char *path)
 600 {
 601         update_file_flags(sha, mode, path, index_only || clean, !index_only);
 602 }
 603
 604 /* Low level file merging, update and removal */
 605
 606 struct merge_file_info
 607 {
 608         unsigned char sha[20];
 609         unsigned mode;
 610         unsigned clean:1,
 611                  merge:1;
 612 };
 613
 614 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 615 {
 616         unsigned long size;
 617         enum object_type type;
 618
 619         if (!hashcmp(sha1, null_sha1)) {
 620                 mm->ptr = xstrdup("");
 621                 mm->size = 0;
 622                 return;
 623         }
 624
 625         mm->ptr = read_sha1_file(sha1, &type, &size);
 626         if (!mm->ptr || type != OBJ_BLOB)
 627                 die("unable to read blob object %s", sha1_to_hex(sha1));
 628         mm->size = size;
 629 }
 630
 631 static int merge_3way(mmbuffer_t *result_buf,
 632                       struct diff_filespec *o,
 633                       struct diff_filespec *a,
 634                       struct diff_filespec *b,
 635                       const char *branch1,
 636                       const char *branch2)
 637 {
 638         mmfile_t orig, src1, src2;
 639         char *name1, *name2;
 640         int merge_status;
 641
 642         name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 643         name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 644
 645         fill_mm(o->sha1, &orig);
 646         fill_mm(a->sha1, &src1);
 647         fill_mm(b->sha1, &src2);
 648
 649         merge_status = ll_merge(result_buf, a->path, &orig,
 650                                 &src1, name1, &src2, name2,
 651                                 index_only);
 652
 653         free(name1);
 654         free(name2);
 655         free(orig.ptr);
 656         free(src1.ptr);
 657         free(src2.ptr);
 658         return merge_status;
 659 }
 660
 661 static struct merge_file_info merge_file(struct diff_filespec *o,
 662                 struct diff_filespec *a, struct diff_filespec *b,
 663                 const char *branch1, const char *branch2)
 664 {
 665         struct merge_file_info result;
 666         result.merge = 0;
 667         result.clean = 1;
 668
 669         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 670                 result.clean = 0;
 671                 if (S_ISREG(a->mode)) {
 672                         result.mode = a->mode;
 673                         hashcpy(result.sha, a->sha1);
 674                 } else {
 675                         result.mode = b->mode;
 676                         hashcpy(result.sha, b->sha1);
 677                 }
 678         } else {
 679                 if (!sha_eq(a->sha1, o->sha1) && !sha_eq(b->sha1, o->sha1))
 680                         result.merge = 1;
 681
 682                 /*
 683                  * Merge modes
 684                  */
 685                 if (a->mode == b->mode || a->mode == o->mode)
 686                         result.mode = b->mode;
 687                 else {
 688                         result.mode = a->mode;
 689                         if (b->mode != o->mode) {
 690                                 result.clean = 0;
 691                                 result.merge = 1;
 692                         }
 693                 }
 694
 695                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, o->sha1))
 696                         hashcpy(result.sha, b->sha1);
 697                 else if (sha_eq(b->sha1, o->sha1))
 698                         hashcpy(result.sha, a->sha1);
 699                 else if (S_ISREG(a->mode)) {
 700                         mmbuffer_t result_buf;
 701                         int merge_status;
 702
 703                         merge_status = merge_3way(&result_buf, o, a, b,
 704                                                   branch1, branch2);
 705
 706                         if ((merge_status < 0) || !result_buf.ptr)
 707                                 die("Failed to execute internal merge");
 708
 709                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 710                                             blob_type, result.sha))
 711                                 die("Unable to add %s to database",
 712                                     a->path);
 713
 714                         free(result_buf.ptr);
 715                         result.clean = (merge_status == 0);
 716                 } else if (S_ISGITLINK(a->mode)) {
 717                         result.clean = 0;
 718                         hashcpy(result.sha, a->sha1);
 719                 } else if (S_ISLNK(a->mode)) {
 720                         hashcpy(result.sha, a->sha1);
 721
 722                         if (!sha_eq(a->sha1, b->sha1))
 723                                 result.clean = 0;
 724                 } else {
 725                         die("unsupported object type in the tree");
 726                 }
 727         }
 728
 729         return result;
 730 }
 731
 732 static void conflict_rename_rename(struct rename *ren1,
 733                                    const char *branch1,
 734                                    struct rename *ren2,
 735                                    const char *branch2)
 736 {
 737         char *del[2];
 738         int delp = 0;
 739         const char *ren1_dst = ren1->pair->two->path;
 740         const char *ren2_dst = ren2->pair->two->path;
 741         const char *dst_name1 = ren1_dst;
 742         const char *dst_name2 = ren2_dst;
 743         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 744                 dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
 745                 output(1, "%s is a directory in %s added as %s instead",
 746                        ren1_dst, branch2, dst_name1);
 747                 remove_file(0, ren1_dst, 0);
 748         }
 749         if (path_list_has_path(&current_directory_set, ren2_dst)) {
 750                 dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
 751                 output(1, "%s is a directory in %s added as %s instead",
 752                        ren2_dst, branch1, dst_name2);
 753                 remove_file(0, ren2_dst, 0);
 754         }
 755         if (index_only) {
 756                 remove_file_from_cache(dst_name1);
 757                 remove_file_from_cache(dst_name2);
 758                 /*
 759                  * Uncomment to leave the conflicting names in the resulting tree
 760                  *
 761                  * update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
 762                  * update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
 763                  */
 764         } else {
 765                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
 766                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
 767         }
 768         while (delp--)
 769                 free(del[delp]);
 770 }
 771
 772 static void conflict_rename_dir(struct rename *ren1,
 773                                 const char *branch1)
 774 {
 775         char *new_path = unique_path(ren1->pair->two->path, branch1);
 776         output(1, "Renamed %s to %s instead", ren1->pair->one->path, new_path);
 777         remove_file(0, ren1->pair->two->path, 0);
 778         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
 779         free(new_path);
 780 }
 781
 782 static void conflict_rename_rename_2(struct rename *ren1,
 783                                      const char *branch1,
 784                                      struct rename *ren2,
 785                                      const char *branch2)
 786 {
 787         char *new_path1 = unique_path(ren1->pair->two->path, branch1);
 788         char *new_path2 = unique_path(ren2->pair->two->path, branch2);
 789         output(1, "Renamed %s to %s and %s to %s instead",
 790                ren1->pair->one->path, new_path1,
 791                ren2->pair->one->path, new_path2);
 792         remove_file(0, ren1->pair->two->path, 0);
 793         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 794         update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 795         free(new_path2);
 796         free(new_path1);
 797 }
 798
 799 static int process_renames(struct path_list *a_renames,
 800                            struct path_list *b_renames,
 801                            const char *a_branch,
 802                            const char *b_branch)
 803 {
 804         int clean_merge = 1, i, j;
 805         struct path_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
 806         const struct rename *sre;
 807
 808         for (i = 0; i < a_renames->nr; i++) {
 809                 sre = a_renames->items[i].util;
 810                 path_list_insert(sre->pair->two->path, &a_by_dst)->util
 811                         = sre->dst_entry;
 812         }
 813         for (i = 0; i < b_renames->nr; i++) {
 814                 sre = b_renames->items[i].util;
 815                 path_list_insert(sre->pair->two->path, &b_by_dst)->util
 816                         = sre->dst_entry;
 817         }
 818
 819         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 820                 int compare;
 821                 char *src;
 822                 struct path_list *renames1, *renames2, *renames2Dst;
 823                 struct rename *ren1 = NULL, *ren2 = NULL;
 824                 const char *branch1, *branch2;
 825                 const char *ren1_src, *ren1_dst;
 826
 827                 if (i >= a_renames->nr) {
 828                         compare = 1;
 829                         ren2 = b_renames->items[j++].util;
 830                 } else if (j >= b_renames->nr) {
 831                         compare = -1;
 832                         ren1 = a_renames->items[i++].util;
 833                 } else {
 834                         compare = strcmp(a_renames->items[i].path,
 835                                         b_renames->items[j].path);
 836                         if (compare <= 0)
 837                                 ren1 = a_renames->items[i++].util;
 838                         if (compare >= 0)
 839                                 ren2 = b_renames->items[j++].util;
 840                 }
 841
 842                 /* TODO: refactor, so that 1/2 are not needed */
 843                 if (ren1) {
 844                         renames1 = a_renames;
 845                         renames2 = b_renames;
 846                         renames2Dst = &b_by_dst;
 847                         branch1 = a_branch;
 848                         branch2 = b_branch;
 849                 } else {
 850                         struct rename *tmp;
 851                         renames1 = b_renames;
 852                         renames2 = a_renames;
 853                         renames2Dst = &a_by_dst;
 854                         branch1 = b_branch;
 855                         branch2 = a_branch;
 856                         tmp = ren2;
 857                         ren2 = ren1;
 858                         ren1 = tmp;
 859                 }
 860                 src = ren1->pair->one->path;
 861
 862                 ren1->dst_entry->processed = 1;
 863                 ren1->src_entry->processed = 1;
 864
 865                 if (ren1->processed)
 866                         continue;
 867                 ren1->processed = 1;
 868
 869                 ren1_src = ren1->pair->one->path;
 870                 ren1_dst = ren1->pair->two->path;
 871
 872                 if (ren2) {
 873                         const char *ren2_src = ren2->pair->one->path;
 874                         const char *ren2_dst = ren2->pair->two->path;
 875                         /* Renamed in 1 and renamed in 2 */
 876                         if (strcmp(ren1_src, ren2_src) != 0)
 877                                 die("ren1.src != ren2.src");
 878                         ren2->dst_entry->processed = 1;
 879                         ren2->processed = 1;
 880                         if (strcmp(ren1_dst, ren2_dst) != 0) {
 881                                 clean_merge = 0;
 882                                 output(1, "CONFLICT (rename/rename): "
 883                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
 884                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
 885                                        src, ren1_dst, branch1,
 886                                        src, ren2_dst, branch2,
 887                                        index_only ? " (left unresolved)": "");
 888                                 if (index_only) {
 889                                         remove_file_from_cache(src);
 890                                         update_file(0, ren1->pair->one->sha1,
 891                                                     ren1->pair->one->mode, src);
 892                                 }
 893                                 conflict_rename_rename(ren1, branch1, ren2, branch2);
 894                         } else {
 895                                 struct merge_file_info mfi;
 896                                 remove_file(1, ren1_src, 1);
 897                                 mfi = merge_file(ren1->pair->one,
 898                                                  ren1->pair->two,
 899                                                  ren2->pair->two,
 900                                                  branch1,
 901                                                  branch2);
 902                                 if (mfi.merge || !mfi.clean)
 903                                         output(1, "Renamed %s->%s", src, ren1_dst);
 904
 905                                 if (mfi.merge)
 906                                         output(2, "Auto-merged %s", ren1_dst);
 907
 908                                 if (!mfi.clean) {
 909                                         output(1, "CONFLICT (content): merge conflict in %s",
 910                                                ren1_dst);
 911                                         clean_merge = 0;
 912
 913                                         if (!index_only)
 914                                                 update_stages(ren1_dst,
 915                                                               ren1->pair->one,
 916                                                               ren1->pair->two,
 917                                                               ren2->pair->two,
 918                                                               1 /* clear */);
 919                                 }
 920                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 921                         }
 922                 } else {
 923                         /* Renamed in 1, maybe changed in 2 */
 924                         struct path_list_item *item;
 925                         /* we only use sha1 and mode of these */
 926                         struct diff_filespec src_other, dst_other;
 927                         int try_merge, stage = a_renames == renames1 ? 3: 2;
 928
 929                         remove_file(1, ren1_src, index_only || stage == 3);
 930
 931                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
 932                         src_other.mode = ren1->src_entry->stages[stage].mode;
 933                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
 934                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
 935
 936                         try_merge = 0;
 937
 938                         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 939                                 clean_merge = 0;
 940                                 output(1, "CONFLICT (rename/directory): Renamed %s->%s in %s "
 941                                        " directory %s added in %s",
 942                                        ren1_src, ren1_dst, branch1,
 943                                        ren1_dst, branch2);
 944                                 conflict_rename_dir(ren1, branch1);
 945                         } else if (sha_eq(src_other.sha1, null_sha1)) {
 946                                 clean_merge = 0;
 947                                 output(1, "CONFLICT (rename/delete): Renamed %s->%s in %s "
 948                                        "and deleted in %s",
 949                                        ren1_src, ren1_dst, branch1,
 950                                        branch2);
 951                                 update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
 952                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
 953                                 const char *new_path;
 954                                 clean_merge = 0;
 955                                 try_merge = 1;
 956                                 output(1, "CONFLICT (rename/add): Renamed %s->%s in %s. "
 957                                        "%s added in %s",
 958                                        ren1_src, ren1_dst, branch1,
 959                                        ren1_dst, branch2);
 960                                 new_path = unique_path(ren1_dst, branch2);
 961                                 output(1, "Added as %s instead", new_path);
 962                                 update_file(0, dst_other.sha1, dst_other.mode, new_path);
 963                         } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
 964                                 ren2 = item->util;
 965                                 clean_merge = 0;
 966                                 ren2->processed = 1;
 967                                 output(1, "CONFLICT (rename/rename): Renamed %s->%s in %s. "
 968                                        "Renamed %s->%s in %s",
 969                                        ren1_src, ren1_dst, branch1,
 970                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
 971                                 conflict_rename_rename_2(ren1, branch1, ren2, branch2);
 972                         } else
 973                                 try_merge = 1;
 974
 975                         if (try_merge) {
 976                                 struct diff_filespec *o, *a, *b;
 977                                 struct merge_file_info mfi;
 978                                 src_other.path = (char *)ren1_src;
 979
 980                                 o = ren1->pair->one;
 981                                 if (a_renames == renames1) {
 982                                         a = ren1->pair->two;
 983                                         b = &src_other;
 984                                 } else {
 985                                         b = ren1->pair->two;
 986                                         a = &src_other;
 987                                 }
 988                                 mfi = merge_file(o, a, b,
 989                                                 a_branch, b_branch);
 990
 991                                 if (mfi.clean &&
 992                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
 993                                     mfi.mode == ren1->pair->two->mode)
 994                                         /*
 995                                          * This messaged is part of
 996                                          * t6022 test. If you change
 997                                          * it update the test too.
 998                                          */
 999                                         output(3, "Skipped %s (merged same as existing)", ren1_dst);
1000                                 else {
1001                                         if (mfi.merge || !mfi.clean)
1002                                                 output(1, "Renamed %s => %s", ren1_src, ren1_dst);
1003                                         if (mfi.merge)
1004                                                 output(2, "Auto-merged %s", ren1_dst);
1005                                         if (!mfi.clean) {
1006                                                 output(1, "CONFLICT (rename/modify): Merge conflict in %s",
1007                                                        ren1_dst);
1008                                                 clean_merge = 0;
1009
1010                                                 if (!index_only)
1011                                                         update_stages(ren1_dst,
1012                                                                       o, a, b, 1);
1013                                         }
1014                                         update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1015                                 }
1016                         }
1017                 }
1018         }
1019         path_list_clear(&a_by_dst, 0);
1020         path_list_clear(&b_by_dst, 0);
1021
1022         return clean_merge;
1023 }
1024
1025 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1026 {
1027         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1028 }
1029
1030 /* Per entry merge function */
1031 static int process_entry(const char *path, struct stage_data *entry,
1032                          const char *branch1,
1033                          const char *branch2)
1034 {
1035         /*
1036         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1037         print_index_entry("\tpath: ", entry);
1038         */
1039         int clean_merge = 1;
1040         unsigned o_mode = entry->stages[1].mode;
1041         unsigned a_mode = entry->stages[2].mode;
1042         unsigned b_mode = entry->stages[3].mode;
1043         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1044         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1045         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1046
1047         if (o_sha && (!a_sha || !b_sha)) {
1048                 /* Case A: Deleted in one */
1049                 if ((!a_sha && !b_sha) ||
1050                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1051                     (!a_sha && sha_eq(b_sha, o_sha))) {
1052                         /* Deleted in both or deleted in one and
1053                          * unchanged in the other */
1054                         if (a_sha)
1055                                 output(2, "Removed %s", path);
1056                         /* do not touch working file if it did not exist */
1057                         remove_file(1, path, !a_sha);
1058                 } else {
1059                         /* Deleted in one and changed in the other */
1060                         clean_merge = 0;
1061                         if (!a_sha) {
1062                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1063                                        "and modified in %s. Version %s of %s left in tree.",
1064                                        path, branch1,
1065                                        branch2, branch2, path);
1066                                 update_file(0, b_sha, b_mode, path);
1067                         } else {
1068                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1069                                        "and modified in %s. Version %s of %s left in tree.",
1070                                        path, branch2,
1071                                        branch1, branch1, path);
1072                                 update_file(0, a_sha, a_mode, path);
1073                         }
1074                 }
1075
1076         } else if ((!o_sha && a_sha && !b_sha) ||
1077                    (!o_sha && !a_sha && b_sha)) {
1078                 /* Case B: Added in one. */
1079                 const char *add_branch;
1080                 const char *other_branch;
1081                 unsigned mode;
1082                 const unsigned char *sha;
1083                 const char *conf;
1084
1085                 if (a_sha) {
1086                         add_branch = branch1;
1087                         other_branch = branch2;
1088                         mode = a_mode;
1089                         sha = a_sha;
1090                         conf = "file/directory";
1091                 } else {
1092                         add_branch = branch2;
1093                         other_branch = branch1;
1094                         mode = b_mode;
1095                         sha = b_sha;
1096                         conf = "directory/file";
1097                 }
1098                 if (path_list_has_path(&current_directory_set, path)) {
1099                         const char *new_path = unique_path(path, add_branch);
1100                         clean_merge = 0;
1101                         output(1, "CONFLICT (%s): There is a directory with name %s in %s. "
1102                                "Added %s as %s",
1103                                conf, path, other_branch, path, new_path);
1104                         remove_file(0, path, 0);
1105                         update_file(0, sha, mode, new_path);
1106                 } else {
1107                         output(2, "Added %s", path);
1108                         update_file(1, sha, mode, path);
1109                 }
1110         } else if (a_sha && b_sha) {
1111                 /* Case C: Added in both (check for same permissions) and */
1112                 /* case D: Modified in both, but differently. */
1113                 const char *reason = "content";
1114                 struct merge_file_info mfi;
1115                 struct diff_filespec o, a, b;
1116
1117                 if (!o_sha) {
1118                         reason = "add/add";
1119                         o_sha = (unsigned char *)null_sha1;
1120                 }
1121                 output(2, "Auto-merged %s", path);
1122                 o.path = a.path = b.path = (char *)path;
1123                 hashcpy(o.sha1, o_sha);
1124                 o.mode = o_mode;
1125                 hashcpy(a.sha1, a_sha);
1126                 a.mode = a_mode;
1127                 hashcpy(b.sha1, b_sha);
1128                 b.mode = b_mode;
1129
1130                 mfi = merge_file(&o, &a, &b,
1131                                  branch1, branch2);
1132
1133                 clean_merge = mfi.clean;
1134                 if (mfi.clean)
1135                         update_file(1, mfi.sha, mfi.mode, path);
1136                 else if (S_ISGITLINK(mfi.mode))
1137                         output(1, "CONFLICT (submodule): Merge conflict in %s "
1138                                "- needs %s", path, sha1_to_hex(b.sha1));
1139                 else {
1140                         output(1, "CONFLICT (%s): Merge conflict in %s",
1141                                         reason, path);
1142
1143                         if (index_only)
1144                                 update_file(0, mfi.sha, mfi.mode, path);
1145                         else
1146                                 update_file_flags(mfi.sha, mfi.mode, path,
1147                                               0 /* update_cache */, 1 /* update_working_directory */);
1148                 }
1149         } else if (!o_sha && !a_sha && !b_sha) {
1150                 /*
1151                  * this entry was deleted altogether. a_mode == 0 means
1152                  * we had that path and want to actively remove it.
1153                  */
1154                 remove_file(1, path, !a_mode);
1155         } else
1156                 die("Fatal merge failure, shouldn't happen.");
1157
1158         return clean_merge;
1159 }
1160
1161 int merge_trees(struct tree *head,
1162                 struct tree *merge,
1163                 struct tree *common,
1164                 const char *branch1,
1165                 const char *branch2,
1166                 struct tree **result)
1167 {
1168         int code, clean;
1169
1170         if (subtree_merge) {
1171                 merge = shift_tree_object(head, merge);
1172                 common = shift_tree_object(head, common);
1173         }
1174
1175         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1176                 output(0, "Already uptodate!");
1177                 *result = head;
1178                 return 1;
1179         }
1180
1181         code = git_merge_trees(index_only, common, head, merge);
1182
1183         if (code != 0)
1184                 die("merging of trees %s and %s failed",
1185                     sha1_to_hex(head->object.sha1),
1186                     sha1_to_hex(merge->object.sha1));
1187
1188         if (unmerged_cache()) {
1189                 struct path_list *entries, *re_head, *re_merge;
1190                 int i;
1191                 path_list_clear(&current_file_set, 1);
1192                 path_list_clear(&current_directory_set, 1);
1193                 get_files_dirs(head);
1194                 get_files_dirs(merge);
1195
1196                 entries = get_unmerged();
1197                 re_head  = get_renames(head, common, head, merge, entries);
1198                 re_merge = get_renames(merge, common, head, merge, entries);
1199                 clean = process_renames(re_head, re_merge,
1200                                 branch1, branch2);
1201                 for (i = 0; i < entries->nr; i++) {
1202                         const char *path = entries->items[i].path;
1203                         struct stage_data *e = entries->items[i].util;
1204                         if (!e->processed
1205                                 && !process_entry(path, e, branch1, branch2))
1206                                 clean = 0;
1207                 }
1208
1209                 path_list_clear(re_merge, 0);
1210                 path_list_clear(re_head, 0);
1211                 path_list_clear(entries, 1);
1212
1213         }
1214         else
1215                 clean = 1;
1216
1217         if (index_only)
1218                 *result = write_tree_from_memory();
1219
1220         return clean;
1221 }
1222
1223 static struct commit_list *reverse_commit_list(struct commit_list *list)
1224 {
1225         struct commit_list *next = NULL, *current, *backup;
1226         for (current = list; current; current = backup) {
1227                 backup = current->next;
1228                 current->next = next;
1229                 next = current;
1230         }
1231         return next;
1232 }
1233
1234 /*
1235  * Merge the commits h1 and h2, return the resulting virtual
1236  * commit object and a flag indicating the cleanness of the merge.
1237  */
1238 int merge_recursive(struct commit *h1,
1239                     struct commit *h2,
1240                     const char *branch1,
1241                     const char *branch2,
1242                     struct commit_list *ca,
1243                     struct commit **result)
1244 {
1245         struct commit_list *iter;
1246         struct commit *merged_common_ancestors;
1247         struct tree *mrtree = mrtree;
1248         int clean;
1249
1250         if (show(4)) {
1251                 output(4, "Merging:");
1252                 output_commit_title(h1);
1253                 output_commit_title(h2);
1254         }
1255
1256         if (!ca) {
1257                 ca = get_merge_bases(h1, h2, 1);
1258                 ca = reverse_commit_list(ca);
1259         }
1260
1261         if (show(5)) {
1262                 output(5, "found %u common ancestor(s):", commit_list_count(ca));
1263                 for (iter = ca; iter; iter = iter->next)
1264                         output_commit_title(iter->item);
1265         }
1266
1267         merged_common_ancestors = pop_commit(&ca);
1268         if (merged_common_ancestors == NULL) {
1269                 /* if there is no common ancestor, make an empty tree */
1270                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1271
1272                 tree->object.parsed = 1;
1273                 tree->object.type = OBJ_TREE;
1274                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1275                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1276         }
1277
1278         for (iter = ca; iter; iter = iter->next) {
1279                 call_depth++;
1280                 /*
1281                  * When the merge fails, the result contains files
1282                  * with conflict markers. The cleanness flag is
1283                  * ignored, it was never actually used, as result of
1284                  * merge_trees has always overwritten it: the committed
1285                  * "conflicts" were already resolved.
1286                  */
1287                 discard_cache();
1288                 merge_recursive(merged_common_ancestors, iter->item,
1289                                 "Temporary merge branch 1",
1290                                 "Temporary merge branch 2",
1291                                 NULL,
1292                                 &merged_common_ancestors);
1293                 call_depth--;
1294
1295                 if (!merged_common_ancestors)
1296                         die("merge returned no commit");
1297         }
1298
1299         discard_cache();
1300         if (!call_depth) {
1301                 read_cache();
1302                 index_only = 0;
1303         } else
1304                 index_only = 1;
1305
1306         clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
1307                             branch1, branch2, &mrtree);
1308
1309         if (index_only) {
1310                 *result = make_virtual_commit(mrtree, "merged tree");
1311                 commit_list_insert(h1, &(*result)->parents);
1312                 commit_list_insert(h2, &(*result)->parents->next);
1313         }
1314         flush_output();
1315         return clean;
1316 }
1317
1318 static const char *better_branch_name(const char *branch)
1319 {
1320         static char githead_env[8 + 40 + 1];
1321         char *name;
1322
1323         if (strlen(branch) != 40)
1324                 return branch;
1325         sprintf(githead_env, "GITHEAD_%s", branch);
1326         name = getenv(githead_env);
1327         return name ? name : branch;
1328 }
1329
1330 static struct commit *get_ref(const char *ref)
1331 {
1332         unsigned char sha1[20];
1333         struct object *object;
1334
1335         if (get_sha1(ref, sha1))
1336                 die("Could not resolve ref '%s'", ref);
1337         object = deref_tag(parse_object(sha1), ref, strlen(ref));
1338         if (!object)
1339                 return NULL;
1340         if (object->type == OBJ_TREE)
1341                 return make_virtual_commit((struct tree*)object,
1342                         better_branch_name(ref));
1343         if (object->type != OBJ_COMMIT)
1344                 return NULL;
1345         if (parse_commit((struct commit *)object))
1346                 die("Could not parse commit '%s'", sha1_to_hex(object->sha1));
1347         return (struct commit *)object;
1348 }
1349
1350 static int merge_config(const char *var, const char *value)
1351 {
1352         if (!strcasecmp(var, "merge.verbosity")) {
1353                 verbosity = git_config_int(var, value);
1354                 return 0;
1355         }
1356         if (!strcasecmp(var, "diff.renamelimit")) {
1357                 rename_limit = git_config_int(var, value);
1358                 return 0;
1359         }
1360         return git_default_config(var, value);
1361 }
1362
1363 int cmd_merge_recursive(int argc, const char **argv, const char *prefix)
1364 {
1365         static const char *bases[20];
1366         static unsigned bases_count = 0;
1367         int i, clean;
1368         const char *branch1, *branch2;
1369         struct commit *result, *h1, *h2;
1370         struct commit_list *ca = NULL;
1371         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1372         int index_fd;
1373
1374         if (argv[0]) {
1375                 int namelen = strlen(argv[0]);
1376                 if (8 < namelen &&
1377                     !strcmp(argv[0] + namelen - 8, "-subtree"))
1378                         subtree_merge = 1;
1379         }
1380
1381         git_config(merge_config);
1382         if (getenv("GIT_MERGE_VERBOSITY"))
1383                 verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1384
1385         if (argc < 4)
1386                 die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
1387
1388         for (i = 1; i < argc; ++i) {
1389                 if (!strcmp(argv[i], "--"))
1390                         break;
1391                 if (bases_count < sizeof(bases)/sizeof(*bases))
1392                         bases[bases_count++] = argv[i];
1393         }
1394         if (argc - i != 3) /* "--" "<head>" "<remote>" */
1395                 die("Not handling anything other than two heads merge.");
1396         if (verbosity >= 5)
1397                 buffer_output = 0;
1398
1399         branch1 = argv[++i];
1400         branch2 = argv[++i];
1401
1402         h1 = get_ref(branch1);
1403         h2 = get_ref(branch2);
1404
1405         branch1 = better_branch_name(branch1);
1406         branch2 = better_branch_name(branch2);
1407
1408         if (show(3))
1409                 printf("Merging %s with %s\n", branch1, branch2);
1410
1411         index_fd = hold_locked_index(lock, 1);
1412
1413         for (i = 0; i < bases_count; i++) {
1414                 struct commit *ancestor = get_ref(bases[i]);
1415                 ca = commit_list_insert(ancestor, &ca);
1416         }
1417         clean = merge_recursive(h1, h2, branch1, branch2, ca, &result);
1418
1419         if (active_cache_changed &&
1420             (write_cache(index_fd, active_cache, active_nr) ||
1421              commit_locked_index(lock)))
1422                         die ("unable to write %s", get_index_file());
1423
1424         return clean ? 0: 1;
1425 }