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