merge-recursive.c

   1 /*
   2  * Recursive Merge algorithm stolen from git-merge-recursive.py by
   3  * Fredrik Kuivinen.
   4  * The thieves were Alex Riesen and Johannes Schindelin, in June/July 2006
   5  */
   6 #include "cache.h"
   7 #include "cache-tree.h"
   8 #include "commit.h"
   9 #include "blob.h"
  10 #include "tree-walk.h"
  11 #include "diff.h"
  12 #include "diffcore.h"
  13 #include "tag.h"
  14 #include "unpack-trees.h"
  15 #include "path-list.h"
  16 #include "xdiff-interface.h"
  17 #include "ll-merge.h"
  18
  19 static int subtree_merge;
  20
  21 static struct tree *shift_tree_object(struct tree *one, struct tree *two)
  22 {
  23         unsigned char shifted[20];
  24
  25         /*
  26          * NEEDSWORK: this limits the recursion depth to hardcoded
  27          * value '2' to avoid excessive overhead.
  28          */
  29         shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
  30         if (!hashcmp(two->object.sha1, shifted))
  31                 return two;
  32         return lookup_tree(shifted);
  33 }
  34
  35 /*
  36  * A virtual commit has
  37  * - (const char *)commit->util set to the name, and
  38  * - *(int *)commit->object.sha1 set to the virtual id.
  39  */
  40
  41 static unsigned commit_list_count(const struct commit_list *l)
  42 {
  43         unsigned c = 0;
  44         for (; l; l = l->next )
  45                 c++;
  46         return c;
  47 }
  48
  49 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  50 {
  51         struct commit *commit = xcalloc(1, sizeof(struct commit));
  52         static unsigned virtual_id = 1;
  53         commit->tree = tree;
  54         commit->util = (void*)comment;
  55         *(int*)commit->object.sha1 = virtual_id++;
  56         /* avoid warnings */
  57         commit->object.parsed = 1;
  58         return commit;
  59 }
  60
  61 /*
  62  * Since we use get_tree_entry(), which does not put the read object into
  63  * the object pool, we cannot rely on a == b.
  64  */
  65 static int sha_eq(const unsigned char *a, const unsigned char *b)
  66 {
  67         if (!a && !b)
  68                 return 2;
  69         return a && b && hashcmp(a, b) == 0;
  70 }
  71
  72 /*
  73  * Since we want to write the index eventually, we cannot reuse the index
  74  * for these (temporary) data.
  75  */
  76 struct stage_data
  77 {
  78         struct
  79         {
  80                 unsigned mode;
  81                 unsigned char sha[20];
  82         } stages[4];
  83         unsigned processed:1;
  84 };
  85
  86 static struct path_list current_file_set = {NULL, 0, 0, 1};
  87 static struct path_list current_directory_set = {NULL, 0, 0, 1};
  88
  89 static int call_depth = 0;
  90 static int verbosity = 2;
  91 static int rename_limit = -1;
  92 static int buffer_output = 1;
  93 static struct strbuf obuf = STRBUF_INIT;
  94
  95 static int show(int v)
  96 {
  97         return (!call_depth && verbosity >= v) || verbosity >= 5;
  98 }
  99
 100 static void flush_output(void)
 101 {
 102         if (obuf.len) {
 103                 fputs(obuf.buf, stdout);
 104                 strbuf_reset(&obuf);
 105         }
 106 }
 107
 108 static void output(int v, const char *fmt, ...)
 109 {
 110         int len;
 111         va_list ap;
 112
 113         if (!show(v))
 114                 return;
 115
 116         strbuf_grow(&obuf, call_depth * 2 + 2);
 117         memset(obuf.buf + obuf.len, ' ', call_depth * 2);
 118         strbuf_setlen(&obuf, obuf.len + call_depth * 2);
 119
 120         va_start(ap, fmt);
 121         len = vsnprintf(obuf.buf + obuf.len, strbuf_avail(&obuf), fmt, ap);
 122         va_end(ap);
 123
 124         if (len < 0)
 125                 len = 0;
 126         if (len >= strbuf_avail(&obuf)) {
 127                 strbuf_grow(&obuf, len + 2);
 128                 va_start(ap, fmt);
 129                 len = vsnprintf(obuf.buf + obuf.len, strbuf_avail(&obuf), fmt, ap);
 130                 va_end(ap);
 131                 if (len >= strbuf_avail(&obuf)) {
 132                         die("this should not happen, your snprintf is broken");
 133                 }
 134         }
 135         strbuf_setlen(&obuf, obuf.len + len);
 136         strbuf_add(&obuf, "\n", 1);
 137         if (!buffer_output)
 138                 flush_output();
 139 }
 140
 141 static void output_commit_title(struct commit *commit)
 142 {
 143         int i;
 144         flush_output();
 145         for (i = call_depth; i--;)
 146                 fputs("  ", stdout);
 147         if (commit->util)
 148                 printf("virtual %s\n", (char *)commit->util);
 149         else {
 150                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 151                 if (parse_commit(commit) != 0)
 152                         printf("(bad commit)\n");
 153                 else {
 154                         const char *s;
 155                         int len;
 156                         for (s = commit->buffer; *s; s++)
 157                                 if (*s == '\n' && s[1] == '\n') {
 158                                         s += 2;
 159                                         break;
 160                                 }
 161                         for (len = 0; s[len] && '\n' != s[len]; len++)
 162                                 ; /* do nothing */
 163                         printf("%.*s\n", len, s);
 164                 }
 165         }
 166 }
 167
 168 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 169                 const char *path, int stage, int refresh, int options)
 170 {
 171         struct cache_entry *ce;
 172         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 173         if (!ce)
 174                 return error("addinfo_cache failed for path '%s'", path);
 175         return add_cache_entry(ce, options);
 176 }
 177
 178 /*
 179  * This is a global variable which is used in a number of places but
 180  * only written to in the 'merge' function.
 181  *
 182  * index_only == 1    => Don't leave any non-stage 0 entries in the cache and
 183  *                       don't update the working directory.
 184  *               0    => Leave unmerged entries in the cache and update
 185  *                       the working directory.
 186  */
 187 static int index_only = 0;
 188
 189 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 190 {
 191         parse_tree(tree);
 192         init_tree_desc(desc, tree->buffer, tree->size);
 193 }
 194
 195 static int git_merge_trees(int index_only,
 196                            struct tree *common,
 197                            struct tree *head,
 198                            struct tree *merge)
 199 {
 200         int rc;
 201         struct tree_desc t[3];
 202         struct unpack_trees_options opts;
 203
 204         memset(&opts, 0, sizeof(opts));
 205         if (index_only)
 206                 opts.index_only = 1;
 207         else
 208                 opts.update = 1;
 209         opts.merge = 1;
 210         opts.head_idx = 2;
 211         opts.fn = threeway_merge;
 212
 213         init_tree_desc_from_tree(t+0, common);
 214         init_tree_desc_from_tree(t+1, head);
 215         init_tree_desc_from_tree(t+2, merge);
 216
 217         rc = unpack_trees(3, t, &opts);
 218         cache_tree_free(&active_cache_tree);
 219         return rc;
 220 }
 221
 222 static int unmerged_index(void)
 223 {
 224         int i;
 225         for (i = 0; i < active_nr; i++) {
 226                 struct cache_entry *ce = active_cache[i];
 227                 if (ce_stage(ce))
 228                         return 1;
 229         }
 230         return 0;
 231 }
 232
 233 static struct tree *git_write_tree(void)
 234 {
 235         struct tree *result = NULL;
 236
 237         if (unmerged_index()) {
 238                 int i;
 239                 output(0, "There are unmerged index entries:");
 240                 for (i = 0; i < active_nr; i++) {
 241                         struct cache_entry *ce = active_cache[i];
 242                         if (ce_stage(ce))
 243                                 output(0, "%d %.*s", ce_stage(ce), ce_namelen(ce), ce->name);
 244                 }
 245                 return NULL;
 246         }
 247
 248         if (!active_cache_tree)
 249                 active_cache_tree = cache_tree();
 250
 251         if (!cache_tree_fully_valid(active_cache_tree) &&
 252             cache_tree_update(active_cache_tree,
 253                               active_cache, active_nr, 0, 0) < 0)
 254                 die("error building trees");
 255
 256         result = lookup_tree(active_cache_tree->sha1);
 257
 258         return result;
 259 }
 260
 261 static int save_files_dirs(const unsigned char *sha1,
 262                 const char *base, int baselen, const char *path,
 263                 unsigned int mode, int stage)
 264 {
 265         int len = strlen(path);
 266         char *newpath = xmalloc(baselen + len + 1);
 267         memcpy(newpath, base, baselen);
 268         memcpy(newpath + baselen, path, len);
 269         newpath[baselen + len] = '\0';
 270
 271         if (S_ISDIR(mode))
 272                 path_list_insert(newpath, &current_directory_set);
 273         else
 274                 path_list_insert(newpath, &current_file_set);
 275         free(newpath);
 276
 277         return READ_TREE_RECURSIVE;
 278 }
 279
 280 static int get_files_dirs(struct tree *tree)
 281 {
 282         int n;
 283         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs) != 0)
 284                 return 0;
 285         n = current_file_set.nr + current_directory_set.nr;
 286         return n;
 287 }
 288
 289 /*
 290  * Returns an index_entry instance which doesn't have to correspond to
 291  * a real cache entry in Git's index.
 292  */
 293 static struct stage_data *insert_stage_data(const char *path,
 294                 struct tree *o, struct tree *a, struct tree *b,
 295                 struct path_list *entries)
 296 {
 297         struct path_list_item *item;
 298         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 299         get_tree_entry(o->object.sha1, path,
 300                         e->stages[1].sha, &e->stages[1].mode);
 301         get_tree_entry(a->object.sha1, path,
 302                         e->stages[2].sha, &e->stages[2].mode);
 303         get_tree_entry(b->object.sha1, path,
 304                         e->stages[3].sha, &e->stages[3].mode);
 305         item = path_list_insert(path, entries);
 306         item->util = e;
 307         return e;
 308 }
 309
 310 /*
 311  * Create a dictionary mapping file names to stage_data objects. The
 312  * dictionary contains one entry for every path with a non-zero stage entry.
 313  */
 314 static struct path_list *get_unmerged(void)
 315 {
 316         struct path_list *unmerged = xcalloc(1, sizeof(struct path_list));
 317         int i;
 318
 319         unmerged->strdup_paths = 1;
 320
 321         for (i = 0; i < active_nr; i++) {
 322                 struct path_list_item *item;
 323                 struct stage_data *e;
 324                 struct cache_entry *ce = active_cache[i];
 325                 if (!ce_stage(ce))
 326                         continue;
 327
 328                 item = path_list_lookup(ce->name, unmerged);
 329                 if (!item) {
 330                         item = path_list_insert(ce->name, unmerged);
 331                         item->util = xcalloc(1, sizeof(struct stage_data));
 332                 }
 333                 e = item->util;
 334                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
 335                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 336         }
 337
 338         return unmerged;
 339 }
 340
 341 struct rename
 342 {
 343         struct diff_filepair *pair;
 344         struct stage_data *src_entry;
 345         struct stage_data *dst_entry;
 346         unsigned processed:1;
 347 };
 348
 349 /*
 350  * Get information of all renames which occurred between 'o_tree' and
 351  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 352  * 'b_tree') to be able to associate the correct cache entries with
 353  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 354  */
 355 static struct path_list *get_renames(struct tree *tree,
 356                                         struct tree *o_tree,
 357                                         struct tree *a_tree,
 358                                         struct tree *b_tree,
 359                                         struct path_list *entries)
 360 {
 361         int i;
 362         struct path_list *renames;
 363         struct diff_options opts;
 364
 365         renames = xcalloc(1, sizeof(struct path_list));
 366         diff_setup(&opts);
 367         DIFF_OPT_SET(&opts, RECURSIVE);
 368         opts.detect_rename = DIFF_DETECT_RENAME;
 369         opts.rename_limit = rename_limit;
 370         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 371         if (diff_setup_done(&opts) < 0)
 372                 die("diff setup failed");
 373         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 374         diffcore_std(&opts);
 375         for (i = 0; i < diff_queued_diff.nr; ++i) {
 376                 struct path_list_item *item;
 377                 struct rename *re;
 378                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 379                 if (pair->status != 'R') {
 380                         diff_free_filepair(pair);
 381                         continue;
 382                 }
 383                 re = xmalloc(sizeof(*re));
 384                 re->processed = 0;
 385                 re->pair = pair;
 386                 item = path_list_lookup(re->pair->one->path, entries);
 387                 if (!item)
 388                         re->src_entry = insert_stage_data(re->pair->one->path,
 389                                         o_tree, a_tree, b_tree, entries);
 390                 else
 391                         re->src_entry = item->util;
 392
 393                 item = path_list_lookup(re->pair->two->path, entries);
 394                 if (!item)
 395                         re->dst_entry = insert_stage_data(re->pair->two->path,
 396                                         o_tree, a_tree, b_tree, entries);
 397                 else
 398                         re->dst_entry = item->util;
 399                 item = path_list_insert(pair->one->path, renames);
 400                 item->util = re;
 401         }
 402         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 403         diff_queued_diff.nr = 0;
 404         diff_flush(&opts);
 405         return renames;
 406 }
 407
 408 static int update_stages(const char *path, struct diff_filespec *o,
 409                          struct diff_filespec *a, struct diff_filespec *b,
 410                          int clear)
 411 {
 412         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 413         if (clear)
 414                 if (remove_file_from_cache(path))
 415                         return -1;
 416         if (o)
 417                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 418                         return -1;
 419         if (a)
 420                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 421                         return -1;
 422         if (b)
 423                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 424                         return -1;
 425         return 0;
 426 }
 427
 428 static int remove_path(const char *name)
 429 {
 430         int ret;
 431         char *slash, *dirs;
 432
 433         ret = unlink(name);
 434         if (ret)
 435                 return ret;
 436         dirs = xstrdup(name);
 437         while ((slash = strrchr(name, '/'))) {
 438                 *slash = '\0';
 439                 if (rmdir(name) != 0)
 440                         break;
 441         }
 442         free(dirs);
 443         return ret;
 444 }
 445
 446 static int remove_file(int clean, const char *path, int no_wd)
 447 {
 448         int update_cache = index_only || clean;
 449         int update_working_directory = !index_only && !no_wd;
 450
 451         if (update_cache) {
 452                 if (remove_file_from_cache(path))
 453                         return -1;
 454         }
 455         if (update_working_directory) {
 456                 unlink(path);
 457                 if (errno != ENOENT || errno != EISDIR)
 458                         return -1;
 459                 remove_path(path);
 460         }
 461         return 0;
 462 }
 463
 464 static char *unique_path(const char *path, const char *branch)
 465 {
 466         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 467         int suffix = 0;
 468         struct stat st;
 469         char *p = newpath + strlen(path);
 470         strcpy(newpath, path);
 471         *(p++) = '~';
 472         strcpy(p, branch);
 473         for (; *p; ++p)
 474                 if ('/' == *p)
 475                         *p = '_';
 476         while (path_list_has_path(&current_file_set, newpath) ||
 477                path_list_has_path(&current_directory_set, newpath) ||
 478                lstat(newpath, &st) == 0)
 479                 sprintf(p, "_%d", suffix++);
 480
 481         path_list_insert(newpath, &current_file_set);
 482         return newpath;
 483 }
 484
 485 static int mkdir_p(const char *path, unsigned long mode)
 486 {
 487         /* path points to cache entries, so xstrdup before messing with it */
 488         char *buf = xstrdup(path);
 489         int result = safe_create_leading_directories(buf);
 490         free(buf);
 491         return result;
 492 }
 493
 494 static void flush_buffer(int fd, const char *buf, unsigned long size)
 495 {
 496         while (size > 0) {
 497                 long ret = write_in_full(fd, buf, size);
 498                 if (ret < 0) {
 499                         /* Ignore epipe */
 500                         if (errno == EPIPE)
 501                                 break;
 502                         die("merge-recursive: %s", strerror(errno));
 503                 } else if (!ret) {
 504                         die("merge-recursive: disk full?");
 505                 }
 506                 size -= ret;
 507                 buf += ret;
 508         }
 509 }
 510
 511 static int make_room_for_path(const char *path)
 512 {
 513         int status;
 514         const char *msg = "failed to create path '%s'%s";
 515
 516         status = mkdir_p(path, 0777);
 517         if (status) {
 518                 if (status == -3) {
 519                         /* something else exists */
 520                         error(msg, path, ": perhaps a D/F conflict?");
 521                         return -1;
 522                 }
 523                 die(msg, path, "");
 524         }
 525
 526         /* Successful unlink is good.. */
 527         if (!unlink(path))
 528                 return 0;
 529         /* .. and so is no existing file */
 530         if (errno == ENOENT)
 531                 return 0;
 532         /* .. but not some other error (who really cares what?) */
 533         return error(msg, path, ": perhaps a D/F conflict?");
 534 }
 535
 536 static void update_file_flags(const unsigned char *sha,
 537                               unsigned mode,
 538                               const char *path,
 539                               int update_cache,
 540                               int update_wd)
 541 {
 542         if (index_only)
 543                 update_wd = 0;
 544
 545         if (update_wd) {
 546                 enum object_type type;
 547                 void *buf;
 548                 unsigned long size;
 549
 550                 if (S_ISGITLINK(mode))
 551                         die("cannot read object %s '%s': It is a submodule!",
 552                             sha1_to_hex(sha), path);
 553
 554                 buf = read_sha1_file(sha, &type, &size);
 555                 if (!buf)
 556                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 557                 if (type != OBJ_BLOB)
 558                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 559
 560                 if (make_room_for_path(path) < 0) {
 561                         update_wd = 0;
 562                         goto update_index;
 563                 }
 564                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 565                         int fd;
 566                         if (mode & 0100)
 567                                 mode = 0777;
 568                         else
 569                                 mode = 0666;
 570                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 571                         if (fd < 0)
 572                                 die("failed to open %s: %s", path, strerror(errno));
 573                         flush_buffer(fd, buf, size);
 574                         close(fd);
 575                 } else if (S_ISLNK(mode)) {
 576                         char *lnk = xmemdupz(buf, size);
 577                         mkdir_p(path, 0777);
 578                         unlink(path);
 579                         symlink(lnk, path);
 580                         free(lnk);
 581                 } else
 582                         die("do not know what to do with %06o %s '%s'",
 583                             mode, sha1_to_hex(sha), path);
 584         }
 585  update_index:
 586         if (update_cache)
 587                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 588 }
 589
 590 static void update_file(int clean,
 591                         const unsigned char *sha,
 592                         unsigned mode,
 593                         const char *path)
 594 {
 595         update_file_flags(sha, mode, path, index_only || clean, !index_only);
 596 }
 597
 598 /* Low level file merging, update and removal */
 599
 600 struct merge_file_info
 601 {
 602         unsigned char sha[20];
 603         unsigned mode;
 604         unsigned clean:1,
 605                  merge:1;
 606 };
 607
 608 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 609 {
 610         unsigned long size;
 611         enum object_type type;
 612
 613         if (!hashcmp(sha1, null_sha1)) {
 614                 mm->ptr = xstrdup("");
 615                 mm->size = 0;
 616                 return;
 617         }
 618
 619         mm->ptr = read_sha1_file(sha1, &type, &size);
 620         if (!mm->ptr || type != OBJ_BLOB)
 621                 die("unable to read blob object %s", sha1_to_hex(sha1));
 622         mm->size = size;
 623 }
 624
 625 static int merge_3way(mmbuffer_t *result_buf,
 626                       struct diff_filespec *o,
 627                       struct diff_filespec *a,
 628                       struct diff_filespec *b,
 629                       const char *branch1,
 630                       const char *branch2)
 631 {
 632         mmfile_t orig, src1, src2;
 633         char *name1, *name2;
 634         int merge_status;
 635
 636         name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 637         name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 638
 639         fill_mm(o->sha1, &orig);
 640         fill_mm(a->sha1, &src1);
 641         fill_mm(b->sha1, &src2);
 642
 643         merge_status = ll_merge(result_buf, a->path, &orig,
 644                                 &src1, name1, &src2, name2,
 645                                 index_only);
 646
 647         free(name1);
 648         free(name2);
 649         free(orig.ptr);
 650         free(src1.ptr);
 651         free(src2.ptr);
 652         return merge_status;
 653 }
 654
 655 static struct merge_file_info merge_file(struct diff_filespec *o,
 656                 struct diff_filespec *a, struct diff_filespec *b,
 657                 const char *branch1, const char *branch2)
 658 {
 659         struct merge_file_info result;
 660         result.merge = 0;
 661         result.clean = 1;
 662
 663         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 664                 result.clean = 0;
 665                 if (S_ISREG(a->mode)) {
 666                         result.mode = a->mode;
 667                         hashcpy(result.sha, a->sha1);
 668                 } else {
 669                         result.mode = b->mode;
 670                         hashcpy(result.sha, b->sha1);
 671                 }
 672         } else {
 673                 if (!sha_eq(a->sha1, o->sha1) && !sha_eq(b->sha1, o->sha1))
 674                         result.merge = 1;
 675
 676                 result.mode = a->mode == o->mode ? b->mode: a->mode;
 677
 678                 if (sha_eq(a->sha1, o->sha1))
 679                         hashcpy(result.sha, b->sha1);
 680                 else if (sha_eq(b->sha1, o->sha1))
 681                         hashcpy(result.sha, a->sha1);
 682                 else if (S_ISREG(a->mode)) {
 683                         mmbuffer_t result_buf;
 684                         int merge_status;
 685
 686                         merge_status = merge_3way(&result_buf, o, a, b,
 687                                                   branch1, branch2);
 688
 689                         if ((merge_status < 0) || !result_buf.ptr)
 690                                 die("Failed to execute internal merge");
 691
 692                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 693                                             blob_type, result.sha))
 694                                 die("Unable to add %s to database",
 695                                     a->path);
 696
 697                         free(result_buf.ptr);
 698                         result.clean = (merge_status == 0);
 699                 } else if (S_ISGITLINK(a->mode)) {
 700                         result.clean = 0;
 701                         hashcpy(result.sha, a->sha1);
 702                 } else if (S_ISLNK(a->mode)) {
 703                         hashcpy(result.sha, a->sha1);
 704
 705                         if (!sha_eq(a->sha1, b->sha1))
 706                                 result.clean = 0;
 707                 } else {
 708                         die("unsupported object type in the tree");
 709                 }
 710         }
 711
 712         return result;
 713 }
 714
 715 static void conflict_rename_rename(struct rename *ren1,
 716                                    const char *branch1,
 717                                    struct rename *ren2,
 718                                    const char *branch2)
 719 {
 720         char *del[2];
 721         int delp = 0;
 722         const char *ren1_dst = ren1->pair->two->path;
 723         const char *ren2_dst = ren2->pair->two->path;
 724         const char *dst_name1 = ren1_dst;
 725         const char *dst_name2 = ren2_dst;
 726         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 727                 dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
 728                 output(1, "%s is a directory in %s added as %s instead",
 729                        ren1_dst, branch2, dst_name1);
 730                 remove_file(0, ren1_dst, 0);
 731         }
 732         if (path_list_has_path(&current_directory_set, ren2_dst)) {
 733                 dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
 734                 output(1, "%s is a directory in %s added as %s instead",
 735                        ren2_dst, branch1, dst_name2);
 736                 remove_file(0, ren2_dst, 0);
 737         }
 738         if (index_only) {
 739                 remove_file_from_cache(dst_name1);
 740                 remove_file_from_cache(dst_name2);
 741                 /*
 742                  * Uncomment to leave the conflicting names in the resulting tree
 743                  *
 744                  * update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
 745                  * update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
 746                  */
 747         } else {
 748                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
 749                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
 750         }
 751         while (delp--)
 752                 free(del[delp]);
 753 }
 754
 755 static void conflict_rename_dir(struct rename *ren1,
 756                                 const char *branch1)
 757 {
 758         char *new_path = unique_path(ren1->pair->two->path, branch1);
 759         output(1, "Renamed %s to %s instead", ren1->pair->one->path, new_path);
 760         remove_file(0, ren1->pair->two->path, 0);
 761         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
 762         free(new_path);
 763 }
 764
 765 static void conflict_rename_rename_2(struct rename *ren1,
 766                                      const char *branch1,
 767                                      struct rename *ren2,
 768                                      const char *branch2)
 769 {
 770         char *new_path1 = unique_path(ren1->pair->two->path, branch1);
 771         char *new_path2 = unique_path(ren2->pair->two->path, branch2);
 772         output(1, "Renamed %s to %s and %s to %s instead",
 773                ren1->pair->one->path, new_path1,
 774                ren2->pair->one->path, new_path2);
 775         remove_file(0, ren1->pair->two->path, 0);
 776         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 777         update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 778         free(new_path2);
 779         free(new_path1);
 780 }
 781
 782 static int process_renames(struct path_list *a_renames,
 783                            struct path_list *b_renames,
 784                            const char *a_branch,
 785                            const char *b_branch)
 786 {
 787         int clean_merge = 1, i, j;
 788         struct path_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
 789         const struct rename *sre;
 790
 791         for (i = 0; i < a_renames->nr; i++) {
 792                 sre = a_renames->items[i].util;
 793                 path_list_insert(sre->pair->two->path, &a_by_dst)->util
 794                         = sre->dst_entry;
 795         }
 796         for (i = 0; i < b_renames->nr; i++) {
 797                 sre = b_renames->items[i].util;
 798                 path_list_insert(sre->pair->two->path, &b_by_dst)->util
 799                         = sre->dst_entry;
 800         }
 801
 802         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 803                 int compare;
 804                 char *src;
 805                 struct path_list *renames1, *renames2, *renames2Dst;
 806                 struct rename *ren1 = NULL, *ren2 = NULL;
 807                 const char *branch1, *branch2;
 808                 const char *ren1_src, *ren1_dst;
 809
 810                 if (i >= a_renames->nr) {
 811                         compare = 1;
 812                         ren2 = b_renames->items[j++].util;
 813                 } else if (j >= b_renames->nr) {
 814                         compare = -1;
 815                         ren1 = a_renames->items[i++].util;
 816                 } else {
 817                         compare = strcmp(a_renames->items[i].path,
 818                                         b_renames->items[j].path);
 819                         if (compare <= 0)
 820                                 ren1 = a_renames->items[i++].util;
 821                         if (compare >= 0)
 822                                 ren2 = b_renames->items[j++].util;
 823                 }
 824
 825                 /* TODO: refactor, so that 1/2 are not needed */
 826                 if (ren1) {
 827                         renames1 = a_renames;
 828                         renames2 = b_renames;
 829                         renames2Dst = &b_by_dst;
 830                         branch1 = a_branch;
 831                         branch2 = b_branch;
 832                 } else {
 833                         struct rename *tmp;
 834                         renames1 = b_renames;
 835                         renames2 = a_renames;
 836                         renames2Dst = &a_by_dst;
 837                         branch1 = b_branch;
 838                         branch2 = a_branch;
 839                         tmp = ren2;
 840                         ren2 = ren1;
 841                         ren1 = tmp;
 842                 }
 843                 src = ren1->pair->one->path;
 844
 845                 ren1->dst_entry->processed = 1;
 846                 ren1->src_entry->processed = 1;
 847
 848                 if (ren1->processed)
 849                         continue;
 850                 ren1->processed = 1;
 851
 852                 ren1_src = ren1->pair->one->path;
 853                 ren1_dst = ren1->pair->two->path;
 854
 855                 if (ren2) {
 856                         const char *ren2_src = ren2->pair->one->path;
 857                         const char *ren2_dst = ren2->pair->two->path;
 858                         /* Renamed in 1 and renamed in 2 */
 859                         if (strcmp(ren1_src, ren2_src) != 0)
 860                                 die("ren1.src != ren2.src");
 861                         ren2->dst_entry->processed = 1;
 862                         ren2->processed = 1;
 863                         if (strcmp(ren1_dst, ren2_dst) != 0) {
 864                                 clean_merge = 0;
 865                                 output(1, "CONFLICT (rename/rename): "
 866                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
 867                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
 868                                        src, ren1_dst, branch1,
 869                                        src, ren2_dst, branch2,
 870                                        index_only ? " (left unresolved)": "");
 871                                 if (index_only) {
 872                                         remove_file_from_cache(src);
 873                                         update_file(0, ren1->pair->one->sha1,
 874                                                     ren1->pair->one->mode, src);
 875                                 }
 876                                 conflict_rename_rename(ren1, branch1, ren2, branch2);
 877                         } else {
 878                                 struct merge_file_info mfi;
 879                                 remove_file(1, ren1_src, 1);
 880                                 mfi = merge_file(ren1->pair->one,
 881                                                  ren1->pair->two,
 882                                                  ren2->pair->two,
 883                                                  branch1,
 884                                                  branch2);
 885                                 if (mfi.merge || !mfi.clean)
 886                                         output(1, "Renamed %s->%s", src, ren1_dst);
 887
 888                                 if (mfi.merge)
 889                                         output(2, "Auto-merged %s", ren1_dst);
 890
 891                                 if (!mfi.clean) {
 892                                         output(1, "CONFLICT (content): merge conflict in %s",
 893                                                ren1_dst);
 894                                         clean_merge = 0;
 895
 896                                         if (!index_only)
 897                                                 update_stages(ren1_dst,
 898                                                               ren1->pair->one,
 899                                                               ren1->pair->two,
 900                                                               ren2->pair->two,
 901                                                               1 /* clear */);
 902                                 }
 903                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 904                         }
 905                 } else {
 906                         /* Renamed in 1, maybe changed in 2 */
 907                         struct path_list_item *item;
 908                         /* we only use sha1 and mode of these */
 909                         struct diff_filespec src_other, dst_other;
 910                         int try_merge, stage = a_renames == renames1 ? 3: 2;
 911
 912                         remove_file(1, ren1_src, index_only || stage == 3);
 913
 914                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
 915                         src_other.mode = ren1->src_entry->stages[stage].mode;
 916                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
 917                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
 918
 919                         try_merge = 0;
 920
 921                         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 922                                 clean_merge = 0;
 923                                 output(1, "CONFLICT (rename/directory): Renamed %s->%s in %s "
 924                                        " directory %s added in %s",
 925                                        ren1_src, ren1_dst, branch1,
 926                                        ren1_dst, branch2);
 927                                 conflict_rename_dir(ren1, branch1);
 928                         } else if (sha_eq(src_other.sha1, null_sha1)) {
 929                                 clean_merge = 0;
 930                                 output(1, "CONFLICT (rename/delete): Renamed %s->%s in %s "
 931                                        "and deleted in %s",
 932                                        ren1_src, ren1_dst, branch1,
 933                                        branch2);
 934                                 update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
 935                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
 936                                 const char *new_path;
 937                                 clean_merge = 0;
 938                                 try_merge = 1;
 939                                 output(1, "CONFLICT (rename/add): Renamed %s->%s in %s. "
 940                                        "%s added in %s",
 941                                        ren1_src, ren1_dst, branch1,
 942                                        ren1_dst, branch2);
 943                                 new_path = unique_path(ren1_dst, branch2);
 944                                 output(1, "Added as %s instead", new_path);
 945                                 update_file(0, dst_other.sha1, dst_other.mode, new_path);
 946                         } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
 947                                 ren2 = item->util;
 948                                 clean_merge = 0;
 949                                 ren2->processed = 1;
 950                                 output(1, "CONFLICT (rename/rename): Renamed %s->%s in %s. "
 951                                        "Renamed %s->%s in %s",
 952                                        ren1_src, ren1_dst, branch1,
 953                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
 954                                 conflict_rename_rename_2(ren1, branch1, ren2, branch2);
 955                         } else
 956                                 try_merge = 1;
 957
 958                         if (try_merge) {
 959                                 struct diff_filespec *o, *a, *b;
 960                                 struct merge_file_info mfi;
 961                                 src_other.path = (char *)ren1_src;
 962
 963                                 o = ren1->pair->one;
 964                                 if (a_renames == renames1) {
 965                                         a = ren1->pair->two;
 966                                         b = &src_other;
 967                                 } else {
 968                                         b = ren1->pair->two;
 969                                         a = &src_other;
 970                                 }
 971                                 mfi = merge_file(o, a, b,
 972                                                 a_branch, b_branch);
 973
 974                                 if (mfi.clean &&
 975                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
 976                                     mfi.mode == ren1->pair->two->mode)
 977                                         /*
 978                                          * This messaged is part of
 979                                          * t6022 test. If you change
 980                                          * it update the test too.
 981                                          */
 982                                         output(3, "Skipped %s (merged same as existing)", ren1_dst);
 983                                 else {
 984                                         if (mfi.merge || !mfi.clean)
 985                                                 output(1, "Renamed %s => %s", ren1_src, ren1_dst);
 986                                         if (mfi.merge)
 987                                                 output(2, "Auto-merged %s", ren1_dst);
 988                                         if (!mfi.clean) {
 989                                                 output(1, "CONFLICT (rename/modify): Merge conflict in %s",
 990                                                        ren1_dst);
 991                                                 clean_merge = 0;
 992
 993                                                 if (!index_only)
 994                                                         update_stages(ren1_dst,
 995                                                                       o, a, b, 1);
 996                                         }
 997                                         update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 998                                 }
 999                         }
1000                 }
1001         }
1002         path_list_clear(&a_by_dst, 0);
1003         path_list_clear(&b_by_dst, 0);
1004
1005         return clean_merge;
1006 }
1007
1008 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1009 {
1010         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1011 }
1012
1013 /* Per entry merge function */
1014 static int process_entry(const char *path, struct stage_data *entry,
1015                          const char *branch1,
1016                          const char *branch2)
1017 {
1018         /*
1019         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1020         print_index_entry("\tpath: ", entry);
1021         */
1022         int clean_merge = 1;
1023         unsigned o_mode = entry->stages[1].mode;
1024         unsigned a_mode = entry->stages[2].mode;
1025         unsigned b_mode = entry->stages[3].mode;
1026         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1027         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1028         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1029
1030         if (o_sha && (!a_sha || !b_sha)) {
1031                 /* Case A: Deleted in one */
1032                 if ((!a_sha && !b_sha) ||
1033                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1034                     (!a_sha && sha_eq(b_sha, o_sha))) {
1035                         /* Deleted in both or deleted in one and
1036                          * unchanged in the other */
1037                         if (a_sha)
1038                                 output(2, "Removed %s", path);
1039                         /* do not touch working file if it did not exist */
1040                         remove_file(1, path, !a_sha);
1041                 } else {
1042                         /* Deleted in one and changed in the other */
1043                         clean_merge = 0;
1044                         if (!a_sha) {
1045                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1046                                        "and modified in %s. Version %s of %s left in tree.",
1047                                        path, branch1,
1048                                        branch2, branch2, path);
1049                                 update_file(0, b_sha, b_mode, path);
1050                         } else {
1051                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1052                                        "and modified in %s. Version %s of %s left in tree.",
1053                                        path, branch2,
1054                                        branch1, branch1, path);
1055                                 update_file(0, a_sha, a_mode, path);
1056                         }
1057                 }
1058
1059         } else if ((!o_sha && a_sha && !b_sha) ||
1060                    (!o_sha && !a_sha && b_sha)) {
1061                 /* Case B: Added in one. */
1062                 const char *add_branch;
1063                 const char *other_branch;
1064                 unsigned mode;
1065                 const unsigned char *sha;
1066                 const char *conf;
1067
1068                 if (a_sha) {
1069                         add_branch = branch1;
1070                         other_branch = branch2;
1071                         mode = a_mode;
1072                         sha = a_sha;
1073                         conf = "file/directory";
1074                 } else {
1075                         add_branch = branch2;
1076                         other_branch = branch1;
1077                         mode = b_mode;
1078                         sha = b_sha;
1079                         conf = "directory/file";
1080                 }
1081                 if (path_list_has_path(&current_directory_set, path)) {
1082                         const char *new_path = unique_path(path, add_branch);
1083                         clean_merge = 0;
1084                         output(1, "CONFLICT (%s): There is a directory with name %s in %s. "
1085                                "Added %s as %s",
1086                                conf, path, other_branch, path, new_path);
1087                         remove_file(0, path, 0);
1088                         update_file(0, sha, mode, new_path);
1089                 } else {
1090                         output(2, "Added %s", path);
1091                         update_file(1, sha, mode, path);
1092                 }
1093         } else if (a_sha && b_sha) {
1094                 /* Case C: Added in both (check for same permissions) and */
1095                 /* case D: Modified in both, but differently. */
1096                 const char *reason = "content";
1097                 struct merge_file_info mfi;
1098                 struct diff_filespec o, a, b;
1099
1100                 if (!o_sha) {
1101                         reason = "add/add";
1102                         o_sha = (unsigned char *)null_sha1;
1103                 }
1104                 output(2, "Auto-merged %s", path);
1105                 o.path = a.path = b.path = (char *)path;
1106                 hashcpy(o.sha1, o_sha);
1107                 o.mode = o_mode;
1108                 hashcpy(a.sha1, a_sha);
1109                 a.mode = a_mode;
1110                 hashcpy(b.sha1, b_sha);
1111                 b.mode = b_mode;
1112
1113                 mfi = merge_file(&o, &a, &b,
1114                                  branch1, branch2);
1115
1116                 clean_merge = mfi.clean;
1117                 if (mfi.clean)
1118                         update_file(1, mfi.sha, mfi.mode, path);
1119                 else if (S_ISGITLINK(mfi.mode))
1120                         output(1, "CONFLICT (submodule): Merge conflict in %s "
1121                                "- needs %s", path, sha1_to_hex(b.sha1));
1122                 else {
1123                         output(1, "CONFLICT (%s): Merge conflict in %s",
1124                                         reason, path);
1125
1126                         if (index_only)
1127                                 update_file(0, mfi.sha, mfi.mode, path);
1128                         else
1129                                 update_file_flags(mfi.sha, mfi.mode, path,
1130                                               0 /* update_cache */, 1 /* update_working_directory */);
1131                 }
1132         } else if (!o_sha && !a_sha && !b_sha) {
1133                 /*
1134                  * this entry was deleted altogether. a_mode == 0 means
1135                  * we had that path and want to actively remove it.
1136                  */
1137                 remove_file(1, path, !a_mode);
1138         } else
1139                 die("Fatal merge failure, shouldn't happen.");
1140
1141         return clean_merge;
1142 }
1143
1144 static int merge_trees(struct tree *head,
1145                        struct tree *merge,
1146                        struct tree *common,
1147                        const char *branch1,
1148                        const char *branch2,
1149                        struct tree **result)
1150 {
1151         int code, clean;
1152
1153         if (subtree_merge) {
1154                 merge = shift_tree_object(head, merge);
1155                 common = shift_tree_object(head, common);
1156         }
1157
1158         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1159                 output(0, "Already uptodate!");
1160                 *result = head;
1161                 return 1;
1162         }
1163
1164         code = git_merge_trees(index_only, common, head, merge);
1165
1166         if (code != 0)
1167                 die("merging of trees %s and %s failed",
1168                     sha1_to_hex(head->object.sha1),
1169                     sha1_to_hex(merge->object.sha1));
1170
1171         if (unmerged_index()) {
1172                 struct path_list *entries, *re_head, *re_merge;
1173                 int i;
1174                 path_list_clear(&current_file_set, 1);
1175                 path_list_clear(&current_directory_set, 1);
1176                 get_files_dirs(head);
1177                 get_files_dirs(merge);
1178
1179                 entries = get_unmerged();
1180                 re_head  = get_renames(head, common, head, merge, entries);
1181                 re_merge = get_renames(merge, common, head, merge, entries);
1182                 clean = process_renames(re_head, re_merge,
1183                                 branch1, branch2);
1184                 for (i = 0; i < entries->nr; i++) {
1185                         const char *path = entries->items[i].path;
1186                         struct stage_data *e = entries->items[i].util;
1187                         if (!e->processed
1188                                 && !process_entry(path, e, branch1, branch2))
1189                                 clean = 0;
1190                 }
1191
1192                 path_list_clear(re_merge, 0);
1193                 path_list_clear(re_head, 0);
1194                 path_list_clear(entries, 1);
1195
1196         }
1197         else
1198                 clean = 1;
1199
1200         if (index_only)
1201                 *result = git_write_tree();
1202
1203         return clean;
1204 }
1205
1206 static struct commit_list *reverse_commit_list(struct commit_list *list)
1207 {
1208         struct commit_list *next = NULL, *current, *backup;
1209         for (current = list; current; current = backup) {
1210                 backup = current->next;
1211                 current->next = next;
1212                 next = current;
1213         }
1214         return next;
1215 }
1216
1217 /*
1218  * Merge the commits h1 and h2, return the resulting virtual
1219  * commit object and a flag indicating the cleanness of the merge.
1220  */
1221 static int merge(struct commit *h1,
1222                  struct commit *h2,
1223                  const char *branch1,
1224                  const char *branch2,
1225                  struct commit_list *ca,
1226                  struct commit **result)
1227 {
1228         struct commit_list *iter;
1229         struct commit *merged_common_ancestors;
1230         struct tree *mrtree = mrtree;
1231         int clean;
1232
1233         if (show(4)) {
1234                 output(4, "Merging:");
1235                 output_commit_title(h1);
1236                 output_commit_title(h2);
1237         }
1238
1239         if (!ca) {
1240                 ca = get_merge_bases(h1, h2, 1);
1241                 ca = reverse_commit_list(ca);
1242         }
1243
1244         if (show(5)) {
1245                 output(5, "found %u common ancestor(s):", commit_list_count(ca));
1246                 for (iter = ca; iter; iter = iter->next)
1247                         output_commit_title(iter->item);
1248         }
1249
1250         merged_common_ancestors = pop_commit(&ca);
1251         if (merged_common_ancestors == NULL) {
1252                 /* if there is no common ancestor, make an empty tree */
1253                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1254
1255                 tree->object.parsed = 1;
1256                 tree->object.type = OBJ_TREE;
1257                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1258                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1259         }
1260
1261         for (iter = ca; iter; iter = iter->next) {
1262                 call_depth++;
1263                 /*
1264                  * When the merge fails, the result contains files
1265                  * with conflict markers. The cleanness flag is
1266                  * ignored, it was never actually used, as result of
1267                  * merge_trees has always overwritten it: the committed
1268                  * "conflicts" were already resolved.
1269                  */
1270                 discard_cache();
1271                 merge(merged_common_ancestors, iter->item,
1272                       "Temporary merge branch 1",
1273                       "Temporary merge branch 2",
1274                       NULL,
1275                       &merged_common_ancestors);
1276                 call_depth--;
1277
1278                 if (!merged_common_ancestors)
1279                         die("merge returned no commit");
1280         }
1281
1282         discard_cache();
1283         if (!call_depth) {
1284                 read_cache();
1285                 index_only = 0;
1286         } else
1287                 index_only = 1;
1288
1289         clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
1290                             branch1, branch2, &mrtree);
1291
1292         if (index_only) {
1293                 *result = make_virtual_commit(mrtree, "merged tree");
1294                 commit_list_insert(h1, &(*result)->parents);
1295                 commit_list_insert(h2, &(*result)->parents->next);
1296         }
1297         flush_output();
1298         return clean;
1299 }
1300
1301 static const char *better_branch_name(const char *branch)
1302 {
1303         static char githead_env[8 + 40 + 1];
1304         char *name;
1305
1306         if (strlen(branch) != 40)
1307                 return branch;
1308         sprintf(githead_env, "GITHEAD_%s", branch);
1309         name = getenv(githead_env);
1310         return name ? name : branch;
1311 }
1312
1313 static struct commit *get_ref(const char *ref)
1314 {
1315         unsigned char sha1[20];
1316         struct object *object;
1317
1318         if (get_sha1(ref, sha1))
1319                 die("Could not resolve ref '%s'", ref);
1320         object = deref_tag(parse_object(sha1), ref, strlen(ref));
1321         if (!object)
1322                 return NULL;
1323         if (object->type == OBJ_TREE)
1324                 return make_virtual_commit((struct tree*)object,
1325                         better_branch_name(ref));
1326         if (object->type != OBJ_COMMIT)
1327                 return NULL;
1328         if (parse_commit((struct commit *)object))
1329                 die("Could not parse commit '%s'", sha1_to_hex(object->sha1));
1330         return (struct commit *)object;
1331 }
1332
1333 static int merge_config(const char *var, const char *value)
1334 {
1335         if (!strcasecmp(var, "merge.verbosity")) {
1336                 verbosity = git_config_int(var, value);
1337                 return 0;
1338         }
1339         if (!strcasecmp(var, "diff.renamelimit")) {
1340                 rename_limit = git_config_int(var, value);
1341                 return 0;
1342         }
1343         return git_default_config(var, value);
1344 }
1345
1346 int main(int argc, char *argv[])
1347 {
1348         static const char *bases[20];
1349         static unsigned bases_count = 0;
1350         int i, clean;
1351         const char *branch1, *branch2;
1352         struct commit *result, *h1, *h2;
1353         struct commit_list *ca = NULL;
1354         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1355         int index_fd;
1356
1357         if (argv[0]) {
1358                 int namelen = strlen(argv[0]);
1359                 if (8 < namelen &&
1360                     !strcmp(argv[0] + namelen - 8, "-subtree"))
1361                         subtree_merge = 1;
1362         }
1363
1364         git_config(merge_config);
1365         if (getenv("GIT_MERGE_VERBOSITY"))
1366                 verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1367
1368         if (argc < 4)
1369                 die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
1370
1371         for (i = 1; i < argc; ++i) {
1372                 if (!strcmp(argv[i], "--"))
1373                         break;
1374                 if (bases_count < sizeof(bases)/sizeof(*bases))
1375                         bases[bases_count++] = argv[i];
1376         }
1377         if (argc - i != 3) /* "--" "<head>" "<remote>" */
1378                 die("Not handling anything other than two heads merge.");
1379         if (verbosity >= 5)
1380                 buffer_output = 0;
1381
1382         branch1 = argv[++i];
1383         branch2 = argv[++i];
1384
1385         h1 = get_ref(branch1);
1386         h2 = get_ref(branch2);
1387
1388         branch1 = better_branch_name(branch1);
1389         branch2 = better_branch_name(branch2);
1390
1391         if (show(3))
1392                 printf("Merging %s with %s\n", branch1, branch2);
1393
1394         index_fd = hold_locked_index(lock, 1);
1395
1396         for (i = 0; i < bases_count; i++) {
1397                 struct commit *ancestor = get_ref(bases[i]);
1398                 ca = commit_list_insert(ancestor, &ca);
1399         }
1400         clean = merge(h1, h2, branch1, branch2, ca, &result);
1401
1402         if (active_cache_changed &&
1403             (write_cache(index_fd, active_cache, active_nr) ||
1404              commit_locked_index(lock)))
1405                         die ("unable to write %s", get_index_file());
1406
1407         return clean ? 0: 1;
1408 }