git.oblomov.eu Git - git/blob - 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 "run-command.h"
  14 #include "tag.h"
  15 #include "unpack-trees.h"
  16 #include "path-list.h"
  17 #include "xdiff-interface.h"
  18 #include "interpolate.h"
  19 #include "attr.h"
  20
  21 static int subtree_merge;
  22
  23 static struct tree *shift_tree_object(struct tree *one, struct tree *two)
  24 {
  25         unsigned char shifted[20];
  26
  27         /*
  28          * NEEDSWORK: this limits the recursion depth to hardcoded
  29          * value '2' to avoid excessive overhead.
  30          */
  31         shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
  32         if (!hashcmp(two->object.sha1, shifted))
  33                 return two;
  34         return lookup_tree(shifted);
  35 }
  36
  37 /*
  38  * A virtual commit has
  39  * - (const char *)commit->util set to the name, and
  40  * - *(int *)commit->object.sha1 set to the virtual id.
  41  */
  42
  43 static unsigned commit_list_count(const struct commit_list *l)
  44 {
  45         unsigned c = 0;
  46         for (; l; l = l->next )
  47                 c++;
  48         return c;
  49 }
  50
  51 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  52 {
  53         struct commit *commit = xcalloc(1, sizeof(struct commit));
  54         static unsigned virtual_id = 1;
  55         commit->tree = tree;
  56         commit->util = (void*)comment;
  57         *(int*)commit->object.sha1 = virtual_id++;
  58         /* avoid warnings */
  59         commit->object.parsed = 1;
  60         return commit;
  61 }
  62
  63 /*
  64  * Since we use get_tree_entry(), which does not put the read object into
  65  * the object pool, we cannot rely on a == b.
  66  */
  67 static int sha_eq(const unsigned char *a, const unsigned char *b)
  68 {
  69         if (!a && !b)
  70                 return 2;
  71         return a && b && hashcmp(a, b) == 0;
  72 }
  73
  74 /*
  75  * Since we want to write the index eventually, we cannot reuse the index
  76  * for these (temporary) data.
  77  */
  78 struct stage_data
  79 {
  80         struct
  81         {
  82                 unsigned mode;
  83                 unsigned char sha[20];
  84         } stages[4];
  85         unsigned processed:1;
  86 };
  87
  88 struct output_buffer
  89 {
  90         struct output_buffer *next;
  91         char *str;
  92 };
  93
  94 static struct path_list current_file_set = {NULL, 0, 0, 1};
  95 static struct path_list current_directory_set = {NULL, 0, 0, 1};
  96
  97 static int call_depth = 0;
  98 static int verbosity = 2;
  99 static int buffer_output = 1;
 100 static struct output_buffer *output_list, *output_end;
 101
 102 static int show (int v)
 103 {
 104         return (!call_depth && verbosity >= v) || verbosity >= 5;
 105 }
 106
 107 static void output(int v, const char *fmt, ...)
 108 {
 109         va_list args;
 110         va_start(args, fmt);
 111         if (buffer_output && show(v)) {
 112                 struct output_buffer *b = xmalloc(sizeof(*b));
 113                 nfvasprintf(&b->str, fmt, args);
 114                 b->next = NULL;
 115                 if (output_end)
 116                         output_end->next = b;
 117                 else
 118                         output_list = b;
 119                 output_end = b;
 120         } else if (show(v)) {
 121                 int i;
 122                 for (i = call_depth; i--;)
 123                         fputs("  ", stdout);
 124                 vfprintf(stdout, fmt, args);
 125                 fputc('\n', stdout);
 126         }
 127         va_end(args);
 128 }
 129
 130 static void flush_output(void)
 131 {
 132         struct output_buffer *b, *n;
 133         for (b = output_list; b; b = n) {
 134                 int i;
 135                 for (i = call_depth; i--;)
 136                         fputs("  ", stdout);
 137                 fputs(b->str, stdout);
 138                 fputc('\n', stdout);
 139                 n = b->next;
 140                 free(b->str);
 141                 free(b);
 142         }
 143         output_list = NULL;
 144         output_end = NULL;
 145 }
 146
 147 static void output_commit_title(struct commit *commit)
 148 {
 149         int i;
 150         flush_output();
 151         for (i = call_depth; i--;)
 152                 fputs("  ", stdout);
 153         if (commit->util)
 154                 printf("virtual %s\n", (char *)commit->util);
 155         else {
 156                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 157                 if (parse_commit(commit) != 0)
 158                         printf("(bad commit)\n");
 159                 else {
 160                         const char *s;
 161                         int len;
 162                         for (s = commit->buffer; *s; s++)
 163                                 if (*s == '\n' && s[1] == '\n') {
 164                                         s += 2;
 165                                         break;
 166                                 }
 167                         for (len = 0; s[len] && '\n' != s[len]; len++)
 168                                 ; /* do nothing */
 169                         printf("%.*s\n", len, s);
 170                 }
 171         }
 172 }
 173
 174 static struct cache_entry *make_cache_entry(unsigned int mode,
 175                 const unsigned char *sha1, const char *path, int stage, int refresh)
 176 {
 177         int size, len;
 178         struct cache_entry *ce;
 179
 180         if (!verify_path(path))
 181                 return NULL;
 182
 183         len = strlen(path);
 184         size = cache_entry_size(len);
 185         ce = xcalloc(1, size);
 186
 187         hashcpy(ce->sha1, sha1);
 188         memcpy(ce->name, path, len);
 189         ce->ce_flags = create_ce_flags(len, stage);
 190         ce->ce_mode = create_ce_mode(mode);
 191
 192         if (refresh)
 193                 return refresh_cache_entry(ce, 0);
 194
 195         return ce;
 196 }
 197
 198 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 199                 const char *path, int stage, int refresh, int options)
 200 {
 201         struct cache_entry *ce;
 202         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 203         if (!ce)
 204                 return error("addinfo_cache failed for path '%s'", path);
 205         return add_cache_entry(ce, options);
 206 }
 207
 208 /*
 209  * This is a global variable which is used in a number of places but
 210  * only written to in the 'merge' function.
 211  *
 212  * index_only == 1    => Don't leave any non-stage 0 entries in the cache and
 213  *                       don't update the working directory.
 214  *               0    => Leave unmerged entries in the cache and update
 215  *                       the working directory.
 216  */
 217 static int index_only = 0;
 218
 219 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 220 {
 221         parse_tree(tree);
 222         init_tree_desc(desc, tree->buffer, tree->size);
 223 }
 224
 225 static int git_merge_trees(int index_only,
 226                            struct tree *common,
 227                            struct tree *head,
 228                            struct tree *merge)
 229 {
 230         int rc;
 231         struct tree_desc t[3];
 232         struct unpack_trees_options opts;
 233
 234         memset(&opts, 0, sizeof(opts));
 235         if (index_only)
 236                 opts.index_only = 1;
 237         else
 238                 opts.update = 1;
 239         opts.merge = 1;
 240         opts.head_idx = 2;
 241         opts.fn = threeway_merge;
 242
 243         init_tree_desc_from_tree(t+0, common);
 244         init_tree_desc_from_tree(t+1, head);
 245         init_tree_desc_from_tree(t+2, merge);
 246
 247         rc = unpack_trees(3, t, &opts);
 248         cache_tree_free(&active_cache_tree);
 249         return rc;
 250 }
 251
 252 static int unmerged_index(void)
 253 {
 254         int i;
 255         for (i = 0; i < active_nr; i++) {
 256                 struct cache_entry *ce = active_cache[i];
 257                 if (ce_stage(ce))
 258                         return 1;
 259         }
 260         return 0;
 261 }
 262
 263 static struct tree *git_write_tree(void)
 264 {
 265         struct tree *result = NULL;
 266
 267         if (unmerged_index()) {
 268                 int i;
 269                 output(0, "There are unmerged index entries:");
 270                 for (i = 0; i < active_nr; i++) {
 271                         struct cache_entry *ce = active_cache[i];
 272                         if (ce_stage(ce))
 273                                 output(0, "%d %.*s", ce_stage(ce), ce_namelen(ce), ce->name);
 274                 }
 275                 return NULL;
 276         }
 277
 278         if (!active_cache_tree)
 279                 active_cache_tree = cache_tree();
 280
 281         if (!cache_tree_fully_valid(active_cache_tree) &&
 282             cache_tree_update(active_cache_tree,
 283                               active_cache, active_nr, 0, 0) < 0)
 284                 die("error building trees");
 285
 286         result = lookup_tree(active_cache_tree->sha1);
 287
 288         return result;
 289 }
 290
 291 static int save_files_dirs(const unsigned char *sha1,
 292                 const char *base, int baselen, const char *path,
 293                 unsigned int mode, int stage)
 294 {
 295         int len = strlen(path);
 296         char *newpath = xmalloc(baselen + len + 1);
 297         memcpy(newpath, base, baselen);
 298         memcpy(newpath + baselen, path, len);
 299         newpath[baselen + len] = '\0';
 300
 301         if (S_ISDIR(mode))
 302                 path_list_insert(newpath, &current_directory_set);
 303         else
 304                 path_list_insert(newpath, &current_file_set);
 305         free(newpath);
 306
 307         return READ_TREE_RECURSIVE;
 308 }
 309
 310 static int get_files_dirs(struct tree *tree)
 311 {
 312         int n;
 313         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs) != 0)
 314                 return 0;
 315         n = current_file_set.nr + current_directory_set.nr;
 316         return n;
 317 }
 318
 319 /*
 320  * Returns a index_entry instance which doesn't have to correspond to
 321  * a real cache entry in Git's index.
 322  */
 323 static struct stage_data *insert_stage_data(const char *path,
 324                 struct tree *o, struct tree *a, struct tree *b,
 325                 struct path_list *entries)
 326 {
 327         struct path_list_item *item;
 328         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 329         get_tree_entry(o->object.sha1, path,
 330                         e->stages[1].sha, &e->stages[1].mode);
 331         get_tree_entry(a->object.sha1, path,
 332                         e->stages[2].sha, &e->stages[2].mode);
 333         get_tree_entry(b->object.sha1, path,
 334                         e->stages[3].sha, &e->stages[3].mode);
 335         item = path_list_insert(path, entries);
 336         item->util = e;
 337         return e;
 338 }
 339
 340 /*
 341  * Create a dictionary mapping file names to stage_data objects. The
 342  * dictionary contains one entry for every path with a non-zero stage entry.
 343  */
 344 static struct path_list *get_unmerged(void)
 345 {
 346         struct path_list *unmerged = xcalloc(1, sizeof(struct path_list));
 347         int i;
 348
 349         unmerged->strdup_paths = 1;
 350
 351         for (i = 0; i < active_nr; i++) {
 352                 struct path_list_item *item;
 353                 struct stage_data *e;
 354                 struct cache_entry *ce = active_cache[i];
 355                 if (!ce_stage(ce))
 356                         continue;
 357
 358                 item = path_list_lookup(ce->name, unmerged);
 359                 if (!item) {
 360                         item = path_list_insert(ce->name, unmerged);
 361                         item->util = xcalloc(1, sizeof(struct stage_data));
 362                 }
 363                 e = item->util;
 364                 e->stages[ce_stage(ce)].mode = ntohl(ce->ce_mode);
 365                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 366         }
 367
 368         return unmerged;
 369 }
 370
 371 struct rename
 372 {
 373         struct diff_filepair *pair;
 374         struct stage_data *src_entry;
 375         struct stage_data *dst_entry;
 376         unsigned processed:1;
 377 };
 378
 379 /*
 380  * Get information of all renames which occurred between 'o_tree' and
 381  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 382  * 'b_tree') to be able to associate the correct cache entries with
 383  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 384  */
 385 static struct path_list *get_renames(struct tree *tree,
 386                                         struct tree *o_tree,
 387                                         struct tree *a_tree,
 388                                         struct tree *b_tree,
 389                                         struct path_list *entries)
 390 {
 391         int i;
 392         struct path_list *renames;
 393         struct diff_options opts;
 394
 395         renames = xcalloc(1, sizeof(struct path_list));
 396         diff_setup(&opts);
 397         opts.recursive = 1;
 398         opts.detect_rename = DIFF_DETECT_RENAME;
 399         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 400         if (diff_setup_done(&opts) < 0)
 401                 die("diff setup failed");
 402         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 403         diffcore_std(&opts);
 404         for (i = 0; i < diff_queued_diff.nr; ++i) {
 405                 struct path_list_item *item;
 406                 struct rename *re;
 407                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 408                 if (pair->status != 'R') {
 409                         diff_free_filepair(pair);
 410                         continue;
 411                 }
 412                 re = xmalloc(sizeof(*re));
 413                 re->processed = 0;
 414                 re->pair = pair;
 415                 item = path_list_lookup(re->pair->one->path, entries);
 416                 if (!item)
 417                         re->src_entry = insert_stage_data(re->pair->one->path,
 418                                         o_tree, a_tree, b_tree, entries);
 419                 else
 420                         re->src_entry = item->util;
 421
 422                 item = path_list_lookup(re->pair->two->path, entries);
 423                 if (!item)
 424                         re->dst_entry = insert_stage_data(re->pair->two->path,
 425                                         o_tree, a_tree, b_tree, entries);
 426                 else
 427                         re->dst_entry = item->util;
 428                 item = path_list_insert(pair->one->path, renames);
 429                 item->util = re;
 430         }
 431         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 432         diff_queued_diff.nr = 0;
 433         diff_flush(&opts);
 434         return renames;
 435 }
 436
 437 static int update_stages(const char *path, struct diff_filespec *o,
 438                          struct diff_filespec *a, struct diff_filespec *b,
 439                          int clear)
 440 {
 441         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 442         if (clear)
 443                 if (remove_file_from_cache(path))
 444                         return -1;
 445         if (o)
 446                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 447                         return -1;
 448         if (a)
 449                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 450                         return -1;
 451         if (b)
 452                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 453                         return -1;
 454         return 0;
 455 }
 456
 457 static int remove_path(const char *name)
 458 {
 459         int ret, len;
 460         char *slash, *dirs;
 461
 462         ret = unlink(name);
 463         if (ret)
 464                 return ret;
 465         len = strlen(name);
 466         dirs = xmalloc(len+1);
 467         memcpy(dirs, name, len);
 468         dirs[len] = '\0';
 469         while ((slash = strrchr(name, '/'))) {
 470                 *slash = '\0';
 471                 len = slash - name;
 472                 if (rmdir(name) != 0)
 473                         break;
 474         }
 475         free(dirs);
 476         return ret;
 477 }
 478
 479 static int remove_file(int clean, const char *path, int no_wd)
 480 {
 481         int update_cache = index_only || clean;
 482         int update_working_directory = !index_only && !no_wd;
 483
 484         if (update_cache) {
 485                 if (remove_file_from_cache(path))
 486                         return -1;
 487         }
 488         if (update_working_directory) {
 489                 unlink(path);
 490                 if (errno != ENOENT || errno != EISDIR)
 491                         return -1;
 492                 remove_path(path);
 493         }
 494         return 0;
 495 }
 496
 497 static char *unique_path(const char *path, const char *branch)
 498 {
 499         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 500         int suffix = 0;
 501         struct stat st;
 502         char *p = newpath + strlen(path);
 503         strcpy(newpath, path);
 504         *(p++) = '~';
 505         strcpy(p, branch);
 506         for (; *p; ++p)
 507                 if ('/' == *p)
 508                         *p = '_';
 509         while (path_list_has_path(&current_file_set, newpath) ||
 510                path_list_has_path(&current_directory_set, newpath) ||
 511                lstat(newpath, &st) == 0)
 512                 sprintf(p, "_%d", suffix++);
 513
 514         path_list_insert(newpath, &current_file_set);
 515         return newpath;
 516 }
 517
 518 static int mkdir_p(const char *path, unsigned long mode)
 519 {
 520         /* path points to cache entries, so xstrdup before messing with it */
 521         char *buf = xstrdup(path);
 522         int result = safe_create_leading_directories(buf);
 523         free(buf);
 524         return result;
 525 }
 526
 527 static void flush_buffer(int fd, const char *buf, unsigned long size)
 528 {
 529         while (size > 0) {
 530                 long ret = write_in_full(fd, buf, size);
 531                 if (ret < 0) {
 532                         /* Ignore epipe */
 533                         if (errno == EPIPE)
 534                                 break;
 535                         die("merge-recursive: %s", strerror(errno));
 536                 } else if (!ret) {
 537                         die("merge-recursive: disk full?");
 538                 }
 539                 size -= ret;
 540                 buf += ret;
 541         }
 542 }
 543
 544 static int make_room_for_path(const char *path)
 545 {
 546         int status;
 547         const char *msg = "failed to create path '%s'%s";
 548
 549         status = mkdir_p(path, 0777);
 550         if (status) {
 551                 if (status == -3) {
 552                         /* something else exists */
 553                         error(msg, path, ": perhaps a D/F conflict?");
 554                         return -1;
 555                 }
 556                 die(msg, path, "");
 557         }
 558
 559         /* Successful unlink is good.. */
 560         if (!unlink(path))
 561                 return 0;
 562         /* .. and so is no existing file */
 563         if (errno == ENOENT)
 564                 return 0;
 565         /* .. but not some other error (who really cares what?) */
 566         return error(msg, path, ": perhaps a D/F conflict?");
 567 }
 568
 569 static void update_file_flags(const unsigned char *sha,
 570                               unsigned mode,
 571                               const char *path,
 572                               int update_cache,
 573                               int update_wd)
 574 {
 575         if (index_only)
 576                 update_wd = 0;
 577
 578         if (update_wd) {
 579                 enum object_type type;
 580                 void *buf;
 581                 unsigned long size;
 582
 583                 buf = read_sha1_file(sha, &type, &size);
 584                 if (!buf)
 585                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 586                 if (type != OBJ_BLOB)
 587                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 588
 589                 if (make_room_for_path(path) < 0) {
 590                         update_wd = 0;
 591                         goto update_index;
 592                 }
 593                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 594                         int fd;
 595                         if (mode & 0100)
 596                                 mode = 0777;
 597                         else
 598                                 mode = 0666;
 599                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 600                         if (fd < 0)
 601                                 die("failed to open %s: %s", path, strerror(errno));
 602                         flush_buffer(fd, buf, size);
 603                         close(fd);
 604                 } else if (S_ISLNK(mode)) {
 605                         char *lnk = xmalloc(size + 1);
 606                         memcpy(lnk, buf, size);
 607                         lnk[size] = '\0';
 608                         mkdir_p(path, 0777);
 609                         unlink(path);
 610                         symlink(lnk, path);
 611                         free(lnk);
 612                 } else
 613                         die("do not know what to do with %06o %s '%s'",
 614                             mode, sha1_to_hex(sha), path);
 615         }
 616  update_index:
 617         if (update_cache)
 618                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 619 }
 620
 621 static void update_file(int clean,
 622                         const unsigned char *sha,
 623                         unsigned mode,
 624                         const char *path)
 625 {
 626         update_file_flags(sha, mode, path, index_only || clean, !index_only);
 627 }
 628
 629 /* Low level file merging, update and removal */
 630
 631 struct merge_file_info
 632 {
 633         unsigned char sha[20];
 634         unsigned mode;
 635         unsigned clean:1,
 636                  merge:1;
 637 };
 638
 639 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 640 {
 641         unsigned long size;
 642         enum object_type type;
 643
 644         if (!hashcmp(sha1, null_sha1)) {
 645                 mm->ptr = xstrdup("");
 646                 mm->size = 0;
 647                 return;
 648         }
 649
 650         mm->ptr = read_sha1_file(sha1, &type, &size);
 651         if (!mm->ptr || type != OBJ_BLOB)
 652                 die("unable to read blob object %s", sha1_to_hex(sha1));
 653         mm->size = size;
 654 }
 655
 656 /*
 657  * Customizable low-level merge drivers support.
 658  */
 659
 660 struct ll_merge_driver;
 661 typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
 662                            const char *path,
 663                            mmfile_t *orig,
 664                            mmfile_t *src1, const char *name1,
 665                            mmfile_t *src2, const char *name2,
 666                            mmbuffer_t *result);
 667
 668 struct ll_merge_driver {
 669         const char *name;
 670         const char *description;
 671         ll_merge_fn fn;
 672         const char *recursive;
 673         struct ll_merge_driver *next;
 674         char *cmdline;
 675 };
 676
 677 /*
 678  * Built-in low-levels
 679  */
 680 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 681                            const char *path_unused,
 682                            mmfile_t *orig,
 683                            mmfile_t *src1, const char *name1,
 684                            mmfile_t *src2, const char *name2,
 685                            mmbuffer_t *result)
 686 {
 687         /*
 688          * The tentative merge result is "ours" for the final round,
 689          * or common ancestor for an internal merge.  Still return
 690          * "conflicted merge" status.
 691          */
 692         mmfile_t *stolen = index_only ? orig : src1;
 693
 694         result->ptr = stolen->ptr;
 695         result->size = stolen->size;
 696         stolen->ptr = NULL;
 697         return 1;
 698 }
 699
 700 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 701                         const char *path_unused,
 702                         mmfile_t *orig,
 703                         mmfile_t *src1, const char *name1,
 704                         mmfile_t *src2, const char *name2,
 705                         mmbuffer_t *result)
 706 {
 707         xpparam_t xpp;
 708
 709         if (buffer_is_binary(orig->ptr, orig->size) ||
 710             buffer_is_binary(src1->ptr, src1->size) ||
 711             buffer_is_binary(src2->ptr, src2->size)) {
 712                 warning("Cannot merge binary files: %s vs. %s\n",
 713                         name1, name2);
 714                 return ll_binary_merge(drv_unused, path_unused,
 715                                        orig, src1, name1,
 716                                        src2, name2,
 717                                        result);
 718         }
 719
 720         memset(&xpp, 0, sizeof(xpp));
 721         return xdl_merge(orig,
 722                          src1, name1,
 723                          src2, name2,
 724                          &xpp, XDL_MERGE_ZEALOUS,
 725                          result);
 726 }
 727
 728 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 729                           const char *path_unused,
 730                           mmfile_t *orig,
 731                           mmfile_t *src1, const char *name1,
 732                           mmfile_t *src2, const char *name2,
 733                           mmbuffer_t *result)
 734 {
 735         char *src, *dst;
 736         long size;
 737         const int marker_size = 7;
 738
 739         int status = ll_xdl_merge(drv_unused, path_unused,
 740                                   orig, src1, NULL, src2, NULL, result);
 741         if (status <= 0)
 742                 return status;
 743         size = result->size;
 744         src = dst = result->ptr;
 745         while (size) {
 746                 char ch;
 747                 if ((marker_size < size) &&
 748                     (*src == '<' || *src == '=' || *src == '>')) {
 749                         int i;
 750                         ch = *src;
 751                         for (i = 0; i < marker_size; i++)
 752                                 if (src[i] != ch)
 753                                         goto not_a_marker;
 754                         if (src[marker_size] != '\n')
 755                                 goto not_a_marker;
 756                         src += marker_size + 1;
 757                         size -= marker_size + 1;
 758                         continue;
 759                 }
 760         not_a_marker:
 761                 do {
 762                         ch = *src++;
 763                         *dst++ = ch;
 764                         size--;
 765                 } while (ch != '\n' && size);
 766         }
 767         result->size = dst - result->ptr;
 768         return 0;
 769 }
 770
 771 #define LL_BINARY_MERGE 0
 772 #define LL_TEXT_MERGE 1
 773 #define LL_UNION_MERGE 2
 774 static struct ll_merge_driver ll_merge_drv[] = {
 775         { "binary", "built-in binary merge", ll_binary_merge },
 776         { "text", "built-in 3-way text merge", ll_xdl_merge },
 777         { "union", "built-in union merge", ll_union_merge },
 778 };
 779
 780 static void create_temp(mmfile_t *src, char *path)
 781 {
 782         int fd;
 783
 784         strcpy(path, ".merge_file_XXXXXX");
 785         fd = xmkstemp(path);
 786         if (write_in_full(fd, src->ptr, src->size) != src->size)
 787                 die("unable to write temp-file");
 788         close(fd);
 789 }
 790
 791 /*
 792  * User defined low-level merge driver support.
 793  */
 794 static int ll_ext_merge(const struct ll_merge_driver *fn,
 795                         const char *path,
 796                         mmfile_t *orig,
 797                         mmfile_t *src1, const char *name1,
 798                         mmfile_t *src2, const char *name2,
 799                         mmbuffer_t *result)
 800 {
 801         char temp[3][50];
 802         char cmdbuf[2048];
 803         struct interp table[] = {
 804                 { "%O" },
 805                 { "%A" },
 806                 { "%B" },
 807         };
 808         struct child_process child;
 809         const char *args[20];
 810         int status, fd, i;
 811         struct stat st;
 812
 813         if (fn->cmdline == NULL)
 814                 die("custom merge driver %s lacks command line.", fn->name);
 815
 816         result->ptr = NULL;
 817         result->size = 0;
 818         create_temp(orig, temp[0]);
 819         create_temp(src1, temp[1]);
 820         create_temp(src2, temp[2]);
 821
 822         interp_set_entry(table, 0, temp[0]);
 823         interp_set_entry(table, 1, temp[1]);
 824         interp_set_entry(table, 2, temp[2]);
 825
 826         output(1, "merging %s using %s", path,
 827                fn->description ? fn->description : fn->name);
 828
 829         interpolate(cmdbuf, sizeof(cmdbuf), fn->cmdline, table, 3);
 830
 831         memset(&child, 0, sizeof(child));
 832         child.argv = args;
 833         args[0] = "sh";
 834         args[1] = "-c";
 835         args[2] = cmdbuf;
 836         args[3] = NULL;
 837
 838         status = run_command(&child);
 839         if (status < -ERR_RUN_COMMAND_FORK)
 840                 ; /* failure in run-command */
 841         else
 842                 status = -status;
 843         fd = open(temp[1], O_RDONLY);
 844         if (fd < 0)
 845                 goto bad;
 846         if (fstat(fd, &st))
 847                 goto close_bad;
 848         result->size = st.st_size;
 849         result->ptr = xmalloc(result->size + 1);
 850         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 851                 free(result->ptr);
 852                 result->ptr = NULL;
 853                 result->size = 0;
 854         }
 855  close_bad:
 856         close(fd);
 857  bad:
 858         for (i = 0; i < 3; i++)
 859                 unlink(temp[i]);
 860         return status;
 861 }
 862
 863 /*
 864  * merge.default and merge.driver configuration items
 865  */
 866 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 867 static const char *default_ll_merge;
 868
 869 static int read_merge_config(const char *var, const char *value)
 870 {
 871         struct ll_merge_driver *fn;
 872         const char *ep, *name;
 873         int namelen;
 874
 875         if (!strcmp(var, "merge.default")) {
 876                 if (value)
 877                         default_ll_merge = strdup(value);
 878                 return 0;
 879         }
 880
 881         /*
 882          * We are not interested in anything but "merge.<name>.variable";
 883          * especially, we do not want to look at variables such as
 884          * "merge.summary", "merge.tool", and "merge.verbosity".
 885          */
 886         if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
 887                 return 0;
 888
 889         /*
 890          * Find existing one as we might be processing merge.<name>.var2
 891          * after seeing merge.<name>.var1.
 892          */
 893         name = var + 6;
 894         namelen = ep - name;
 895         for (fn = ll_user_merge; fn; fn = fn->next)
 896                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 897                         break;
 898         if (!fn) {
 899                 char *namebuf;
 900                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
 901                 namebuf = xmalloc(namelen + 1);
 902                 memcpy(namebuf, name, namelen);
 903                 namebuf[namelen] = 0;
 904                 fn->name = namebuf;
 905                 fn->fn = ll_ext_merge;
 906                 fn->next = NULL;
 907                 *ll_user_merge_tail = fn;
 908                 ll_user_merge_tail = &(fn->next);
 909         }
 910
 911         ep++;
 912
 913         if (!strcmp("name", ep)) {
 914                 if (!value)
 915                         return error("%s: lacks value", var);
 916                 fn->description = strdup(value);
 917                 return 0;
 918         }
 919
 920         if (!strcmp("driver", ep)) {
 921                 if (!value)
 922                         return error("%s: lacks value", var);
 923                 /*
 924                  * merge.<name>.driver specifies the command line:
 925                  *
 926                  *      command-line
 927                  *
 928                  * The command-line will be interpolated with the following
 929                  * tokens and is given to the shell:
 930                  *
 931                  *    %O - temporary file name for the merge base.
 932                  *    %A - temporary file name for our version.
 933                  *    %B - temporary file name for the other branches' version.
 934                  *
 935                  * The external merge driver should write the results in the
 936                  * file named by %A, and signal that it has done with zero exit
 937                  * status.
 938                  */
 939                 fn->cmdline = strdup(value);
 940                 return 0;
 941         }
 942
 943         if (!strcmp("recursive", ep)) {
 944                 if (!value)
 945                         return error("%s: lacks value", var);
 946                 fn->recursive = strdup(value);
 947                 return 0;
 948         }
 949
 950         return 0;
 951 }
 952
 953 static void initialize_ll_merge(void)
 954 {
 955         if (ll_user_merge_tail)
 956                 return;
 957         ll_user_merge_tail = &ll_user_merge;
 958         git_config(read_merge_config);
 959 }
 960
 961 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 962 {
 963         struct ll_merge_driver *fn;
 964         const char *name;
 965         int i;
 966
 967         initialize_ll_merge();
 968
 969         if (ATTR_TRUE(merge_attr))
 970                 return &ll_merge_drv[LL_TEXT_MERGE];
 971         else if (ATTR_FALSE(merge_attr))
 972                 return &ll_merge_drv[LL_BINARY_MERGE];
 973         else if (ATTR_UNSET(merge_attr)) {
 974                 if (!default_ll_merge)
 975                         return &ll_merge_drv[LL_TEXT_MERGE];
 976                 else
 977                         name = default_ll_merge;
 978         }
 979         else
 980                 name = merge_attr;
 981
 982         for (fn = ll_user_merge; fn; fn = fn->next)
 983                 if (!strcmp(fn->name, name))
 984                         return fn;
 985
 986         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 987                 if (!strcmp(ll_merge_drv[i].name, name))
 988                         return &ll_merge_drv[i];
 989
 990         /* default to the 3-way */
 991         return &ll_merge_drv[LL_TEXT_MERGE];
 992 }
 993
 994 static const char *git_path_check_merge(const char *path)
 995 {
 996         static struct git_attr_check attr_merge_check;
 997
 998         if (!attr_merge_check.attr)
 999                 attr_merge_check.attr = git_attr("merge", 5);
1000
1001         if (git_checkattr(path, 1, &attr_merge_check))
1002                 return NULL;
1003         return attr_merge_check.value;
1004 }
1005
1006 static int ll_merge(mmbuffer_t *result_buf,
1007                     struct diff_filespec *o,
1008                     struct diff_filespec *a,
1009                     struct diff_filespec *b,
1010                     const char *branch1,
1011                     const char *branch2)
1012 {
1013         mmfile_t orig, src1, src2;
1014         char *name1, *name2;
1015         int merge_status;
1016         const char *ll_driver_name;
1017         const struct ll_merge_driver *driver;
1018
1019         name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
1020         name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
1021
1022         fill_mm(o->sha1, &orig);
1023         fill_mm(a->sha1, &src1);
1024         fill_mm(b->sha1, &src2);
1025
1026         ll_driver_name = git_path_check_merge(a->path);
1027         driver = find_ll_merge_driver(ll_driver_name);
1028
1029         if (index_only && driver->recursive)
1030                 driver = find_ll_merge_driver(driver->recursive);
1031         merge_status = driver->fn(driver, a->path,
1032                                   &orig, &src1, name1, &src2, name2,
1033                                   result_buf);
1034
1035         free(name1);
1036         free(name2);
1037         free(orig.ptr);
1038         free(src1.ptr);
1039         free(src2.ptr);
1040         return merge_status;
1041 }
1042
1043 static struct merge_file_info merge_file(struct diff_filespec *o,
1044                 struct diff_filespec *a, struct diff_filespec *b,
1045                 const char *branch1, const char *branch2)
1046 {
1047         struct merge_file_info result;
1048         result.merge = 0;
1049         result.clean = 1;
1050
1051         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
1052                 result.clean = 0;
1053                 if (S_ISREG(a->mode)) {
1054                         result.mode = a->mode;
1055                         hashcpy(result.sha, a->sha1);
1056                 } else {
1057                         result.mode = b->mode;
1058                         hashcpy(result.sha, b->sha1);
1059                 }
1060         } else {
1061                 if (!sha_eq(a->sha1, o->sha1) && !sha_eq(b->sha1, o->sha1))
1062                         result.merge = 1;
1063
1064                 result.mode = a->mode == o->mode ? b->mode: a->mode;
1065
1066                 if (sha_eq(a->sha1, o->sha1))
1067                         hashcpy(result.sha, b->sha1);
1068                 else if (sha_eq(b->sha1, o->sha1))
1069                         hashcpy(result.sha, a->sha1);
1070                 else if (S_ISREG(a->mode)) {
1071                         mmbuffer_t result_buf;
1072                         int merge_status;
1073
1074                         merge_status = ll_merge(&result_buf, o, a, b,
1075                                                 branch1, branch2);
1076
1077                         if ((merge_status < 0) || !result_buf.ptr)
1078                                 die("Failed to execute internal merge");
1079
1080                         if (write_sha1_file(result_buf.ptr, result_buf.size,
1081                                             blob_type, result.sha))
1082                                 die("Unable to add %s to database",
1083                                     a->path);
1084
1085                         free(result_buf.ptr);
1086                         result.clean = (merge_status == 0);
1087                 } else {
1088                         if (!(S_ISLNK(a->mode) || S_ISLNK(b->mode)))
1089                                 die("cannot merge modes?");
1090
1091                         hashcpy(result.sha, a->sha1);
1092
1093                         if (!sha_eq(a->sha1, b->sha1))
1094                                 result.clean = 0;
1095                 }
1096         }
1097
1098         return result;
1099 }
1100
1101 static void conflict_rename_rename(struct rename *ren1,
1102                                    const char *branch1,
1103                                    struct rename *ren2,
1104                                    const char *branch2)
1105 {
1106         char *del[2];
1107         int delp = 0;
1108         const char *ren1_dst = ren1->pair->two->path;
1109         const char *ren2_dst = ren2->pair->two->path;
1110         const char *dst_name1 = ren1_dst;
1111         const char *dst_name2 = ren2_dst;
1112         if (path_list_has_path(&current_directory_set, ren1_dst)) {
1113                 dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
1114                 output(1, "%s is a directory in %s added as %s instead",
1115                        ren1_dst, branch2, dst_name1);
1116                 remove_file(0, ren1_dst, 0);
1117         }
1118         if (path_list_has_path(&current_directory_set, ren2_dst)) {
1119                 dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
1120                 output(1, "%s is a directory in %s added as %s instead",
1121                        ren2_dst, branch1, dst_name2);
1122                 remove_file(0, ren2_dst, 0);
1123         }
1124         if (index_only) {
1125                 remove_file_from_cache(dst_name1);
1126                 remove_file_from_cache(dst_name2);
1127                 /*
1128                  * Uncomment to leave the conflicting names in the resulting tree
1129                  *
1130                  * update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
1131                  * update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
1132                  */
1133         } else {
1134                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
1135                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
1136         }
1137         while (delp--)
1138                 free(del[delp]);
1139 }
1140
1141 static void conflict_rename_dir(struct rename *ren1,
1142                                 const char *branch1)
1143 {
1144         char *new_path = unique_path(ren1->pair->two->path, branch1);
1145         output(1, "Renamed %s to %s instead", ren1->pair->one->path, new_path);
1146         remove_file(0, ren1->pair->two->path, 0);
1147         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
1148         free(new_path);
1149 }
1150
1151 static void conflict_rename_rename_2(struct rename *ren1,
1152                                      const char *branch1,
1153                                      struct rename *ren2,
1154                                      const char *branch2)
1155 {
1156         char *new_path1 = unique_path(ren1->pair->two->path, branch1);
1157         char *new_path2 = unique_path(ren2->pair->two->path, branch2);
1158         output(1, "Renamed %s to %s and %s to %s instead",
1159                ren1->pair->one->path, new_path1,
1160                ren2->pair->one->path, new_path2);
1161         remove_file(0, ren1->pair->two->path, 0);
1162         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
1163         update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
1164         free(new_path2);
1165         free(new_path1);
1166 }
1167
1168 static int process_renames(struct path_list *a_renames,
1169                            struct path_list *b_renames,
1170                            const char *a_branch,
1171                            const char *b_branch)
1172 {
1173         int clean_merge = 1, i, j;
1174         struct path_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
1175         const struct rename *sre;
1176
1177         for (i = 0; i < a_renames->nr; i++) {
1178                 sre = a_renames->items[i].util;
1179                 path_list_insert(sre->pair->two->path, &a_by_dst)->util
1180                         = sre->dst_entry;
1181         }
1182         for (i = 0; i < b_renames->nr; i++) {
1183                 sre = b_renames->items[i].util;
1184                 path_list_insert(sre->pair->two->path, &b_by_dst)->util
1185                         = sre->dst_entry;
1186         }
1187
1188         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
1189                 int compare;
1190                 char *src;
1191                 struct path_list *renames1, *renames2, *renames2Dst;
1192                 struct rename *ren1 = NULL, *ren2 = NULL;
1193                 const char *branch1, *branch2;
1194                 const char *ren1_src, *ren1_dst;
1195
1196                 if (i >= a_renames->nr) {
1197                         compare = 1;
1198                         ren2 = b_renames->items[j++].util;
1199                 } else if (j >= b_renames->nr) {
1200                         compare = -1;
1201                         ren1 = a_renames->items[i++].util;
1202                 } else {
1203                         compare = strcmp(a_renames->items[i].path,
1204                                         b_renames->items[j].path);
1205                         if (compare <= 0)
1206                                 ren1 = a_renames->items[i++].util;
1207                         if (compare >= 0)
1208                                 ren2 = b_renames->items[j++].util;
1209                 }
1210
1211                 /* TODO: refactor, so that 1/2 are not needed */
1212                 if (ren1) {
1213                         renames1 = a_renames;
1214                         renames2 = b_renames;
1215                         renames2Dst = &b_by_dst;
1216                         branch1 = a_branch;
1217                         branch2 = b_branch;
1218                 } else {
1219                         struct rename *tmp;
1220                         renames1 = b_renames;
1221                         renames2 = a_renames;
1222                         renames2Dst = &a_by_dst;
1223                         branch1 = b_branch;
1224                         branch2 = a_branch;
1225                         tmp = ren2;
1226                         ren2 = ren1;
1227                         ren1 = tmp;
1228                 }
1229                 src = ren1->pair->one->path;
1230
1231                 ren1->dst_entry->processed = 1;
1232                 ren1->src_entry->processed = 1;
1233
1234                 if (ren1->processed)
1235                         continue;
1236                 ren1->processed = 1;
1237
1238                 ren1_src = ren1->pair->one->path;
1239                 ren1_dst = ren1->pair->two->path;
1240
1241                 if (ren2) {
1242                         const char *ren2_src = ren2->pair->one->path;
1243                         const char *ren2_dst = ren2->pair->two->path;
1244                         /* Renamed in 1 and renamed in 2 */
1245                         if (strcmp(ren1_src, ren2_src) != 0)
1246                                 die("ren1.src != ren2.src");
1247                         ren2->dst_entry->processed = 1;
1248                         ren2->processed = 1;
1249                         if (strcmp(ren1_dst, ren2_dst) != 0) {
1250                                 clean_merge = 0;
1251                                 output(1, "CONFLICT (rename/rename): "
1252                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
1253                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
1254                                        src, ren1_dst, branch1,
1255                                        src, ren2_dst, branch2,
1256                                        index_only ? " (left unresolved)": "");
1257                                 if (index_only) {
1258                                         remove_file_from_cache(src);
1259                                         update_file(0, ren1->pair->one->sha1,
1260                                                     ren1->pair->one->mode, src);
1261                                 }
1262                                 conflict_rename_rename(ren1, branch1, ren2, branch2);
1263                         } else {
1264                                 struct merge_file_info mfi;
1265                                 remove_file(1, ren1_src, 1);
1266                                 mfi = merge_file(ren1->pair->one,
1267                                                  ren1->pair->two,
1268                                                  ren2->pair->two,
1269                                                  branch1,
1270                                                  branch2);
1271                                 if (mfi.merge || !mfi.clean)
1272                                         output(1, "Renamed %s->%s", src, ren1_dst);
1273
1274                                 if (mfi.merge)
1275                                         output(2, "Auto-merged %s", ren1_dst);
1276
1277                                 if (!mfi.clean) {
1278                                         output(1, "CONFLICT (content): merge conflict in %s",
1279                                                ren1_dst);
1280                                         clean_merge = 0;
1281
1282                                         if (!index_only)
1283                                                 update_stages(ren1_dst,
1284                                                               ren1->pair->one,
1285                                                               ren1->pair->two,
1286                                                               ren2->pair->two,
1287                                                               1 /* clear */);
1288                                 }
1289                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1290                         }
1291                 } else {
1292                         /* Renamed in 1, maybe changed in 2 */
1293                         struct path_list_item *item;
1294                         /* we only use sha1 and mode of these */
1295                         struct diff_filespec src_other, dst_other;
1296                         int try_merge, stage = a_renames == renames1 ? 3: 2;
1297
1298                         remove_file(1, ren1_src, index_only || stage == 3);
1299
1300                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
1301                         src_other.mode = ren1->src_entry->stages[stage].mode;
1302                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
1303                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
1304
1305                         try_merge = 0;
1306
1307                         if (path_list_has_path(&current_directory_set, ren1_dst)) {
1308                                 clean_merge = 0;
1309                                 output(1, "CONFLICT (rename/directory): Renamed %s->%s in %s "
1310                                        " directory %s added in %s",
1311                                        ren1_src, ren1_dst, branch1,
1312                                        ren1_dst, branch2);
1313                                 conflict_rename_dir(ren1, branch1);
1314                         } else if (sha_eq(src_other.sha1, null_sha1)) {
1315                                 clean_merge = 0;
1316                                 output(1, "CONFLICT (rename/delete): Renamed %s->%s in %s "
1317                                        "and deleted in %s",
1318                                        ren1_src, ren1_dst, branch1,
1319                                        branch2);
1320                                 update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
1321                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
1322                                 const char *new_path;
1323                                 clean_merge = 0;
1324                                 try_merge = 1;
1325                                 output(1, "CONFLICT (rename/add): Renamed %s->%s in %s. "
1326                                        "%s added in %s",
1327                                        ren1_src, ren1_dst, branch1,
1328                                        ren1_dst, branch2);
1329                                 new_path = unique_path(ren1_dst, branch2);
1330                                 output(1, "Added as %s instead", new_path);
1331                                 update_file(0, dst_other.sha1, dst_other.mode, new_path);
1332                         } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
1333                                 ren2 = item->util;
1334                                 clean_merge = 0;
1335                                 ren2->processed = 1;
1336                                 output(1, "CONFLICT (rename/rename): Renamed %s->%s in %s. "
1337                                        "Renamed %s->%s in %s",
1338                                        ren1_src, ren1_dst, branch1,
1339                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
1340                                 conflict_rename_rename_2(ren1, branch1, ren2, branch2);
1341                         } else
1342                                 try_merge = 1;
1343
1344                         if (try_merge) {
1345                                 struct diff_filespec *o, *a, *b;
1346                                 struct merge_file_info mfi;
1347                                 src_other.path = (char *)ren1_src;
1348
1349                                 o = ren1->pair->one;
1350                                 if (a_renames == renames1) {
1351                                         a = ren1->pair->two;
1352                                         b = &src_other;
1353                                 } else {
1354                                         b = ren1->pair->two;
1355                                         a = &src_other;
1356                                 }
1357                                 mfi = merge_file(o, a, b,
1358                                                 a_branch, b_branch);
1359
1360                                 if (mfi.clean &&
1361                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
1362                                     mfi.mode == ren1->pair->two->mode)
1363                                         /*
1364                                          * This messaged is part of
1365                                          * t6022 test. If you change
1366                                          * it update the test too.
1367                                          */
1368                                         output(3, "Skipped %s (merged same as existing)", ren1_dst);
1369                                 else {
1370                                         if (mfi.merge || !mfi.clean)
1371                                                 output(1, "Renamed %s => %s", ren1_src, ren1_dst);
1372                                         if (mfi.merge)
1373                                                 output(2, "Auto-merged %s", ren1_dst);
1374                                         if (!mfi.clean) {
1375                                                 output(1, "CONFLICT (rename/modify): Merge conflict in %s",
1376                                                        ren1_dst);
1377                                                 clean_merge = 0;
1378
1379                                                 if (!index_only)
1380                                                         update_stages(ren1_dst,
1381                                                                       o, a, b, 1);
1382                                         }
1383                                         update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1384                                 }
1385                         }
1386                 }
1387         }
1388         path_list_clear(&a_by_dst, 0);
1389         path_list_clear(&b_by_dst, 0);
1390
1391         return clean_merge;
1392 }
1393
1394 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1395 {
1396         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1397 }
1398
1399 /* Per entry merge function */
1400 static int process_entry(const char *path, struct stage_data *entry,
1401                          const char *branch1,
1402                          const char *branch2)
1403 {
1404         /*
1405         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1406         print_index_entry("\tpath: ", entry);
1407         */
1408         int clean_merge = 1;
1409         unsigned o_mode = entry->stages[1].mode;
1410         unsigned a_mode = entry->stages[2].mode;
1411         unsigned b_mode = entry->stages[3].mode;
1412         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1413         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1414         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1415
1416         if (o_sha && (!a_sha || !b_sha)) {
1417                 /* Case A: Deleted in one */
1418                 if ((!a_sha && !b_sha) ||
1419                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1420                     (!a_sha && sha_eq(b_sha, o_sha))) {
1421                         /* Deleted in both or deleted in one and
1422                          * unchanged in the other */
1423                         if (a_sha)
1424                                 output(2, "Removed %s", path);
1425                         /* do not touch working file if it did not exist */
1426                         remove_file(1, path, !a_sha);
1427                 } else {
1428                         /* Deleted in one and changed in the other */
1429                         clean_merge = 0;
1430                         if (!a_sha) {
1431                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1432                                        "and modified in %s. Version %s of %s left in tree.",
1433                                        path, branch1,
1434                                        branch2, branch2, path);
1435                                 update_file(0, b_sha, b_mode, path);
1436                         } else {
1437                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1438                                        "and modified in %s. Version %s of %s left in tree.",
1439                                        path, branch2,
1440                                        branch1, branch1, path);
1441                                 update_file(0, a_sha, a_mode, path);
1442                         }
1443                 }
1444
1445         } else if ((!o_sha && a_sha && !b_sha) ||
1446                    (!o_sha && !a_sha && b_sha)) {
1447                 /* Case B: Added in one. */
1448                 const char *add_branch;
1449                 const char *other_branch;
1450                 unsigned mode;
1451                 const unsigned char *sha;
1452                 const char *conf;
1453
1454                 if (a_sha) {
1455                         add_branch = branch1;
1456                         other_branch = branch2;
1457                         mode = a_mode;
1458                         sha = a_sha;
1459                         conf = "file/directory";
1460                 } else {
1461                         add_branch = branch2;
1462                         other_branch = branch1;
1463                         mode = b_mode;
1464                         sha = b_sha;
1465                         conf = "directory/file";
1466                 }
1467                 if (path_list_has_path(&current_directory_set, path)) {
1468                         const char *new_path = unique_path(path, add_branch);
1469                         clean_merge = 0;
1470                         output(1, "CONFLICT (%s): There is a directory with name %s in %s. "
1471                                "Added %s as %s",
1472                                conf, path, other_branch, path, new_path);
1473                         remove_file(0, path, 0);
1474                         update_file(0, sha, mode, new_path);
1475                 } else {
1476                         output(2, "Added %s", path);
1477                         update_file(1, sha, mode, path);
1478                 }
1479         } else if (a_sha && b_sha) {
1480                 /* Case C: Added in both (check for same permissions) and */
1481                 /* case D: Modified in both, but differently. */
1482                 const char *reason = "content";
1483                 struct merge_file_info mfi;
1484                 struct diff_filespec o, a, b;
1485
1486                 if (!o_sha) {
1487                         reason = "add/add";
1488                         o_sha = (unsigned char *)null_sha1;
1489                 }
1490                 output(2, "Auto-merged %s", path);
1491                 o.path = a.path = b.path = (char *)path;
1492                 hashcpy(o.sha1, o_sha);
1493                 o.mode = o_mode;
1494                 hashcpy(a.sha1, a_sha);
1495                 a.mode = a_mode;
1496                 hashcpy(b.sha1, b_sha);
1497                 b.mode = b_mode;
1498
1499                 mfi = merge_file(&o, &a, &b,
1500                                  branch1, branch2);
1501
1502                 if (mfi.clean)
1503                         update_file(1, mfi.sha, mfi.mode, path);
1504                 else {
1505                         clean_merge = 0;
1506                         output(1, "CONFLICT (%s): Merge conflict in %s",
1507                                         reason, path);
1508
1509                         if (index_only)
1510                                 update_file(0, mfi.sha, mfi.mode, path);
1511                         else
1512                                 update_file_flags(mfi.sha, mfi.mode, path,
1513                                               0 /* update_cache */, 1 /* update_working_directory */);
1514                 }
1515         } else if (!o_sha && !a_sha && !b_sha) {
1516                 /*
1517                  * this entry was deleted altogether. a_mode == 0 means
1518                  * we had that path and want to actively remove it.
1519                  */
1520                 remove_file(1, path, !a_mode);
1521         } else
1522                 die("Fatal merge failure, shouldn't happen.");
1523
1524         return clean_merge;
1525 }
1526
1527 static int merge_trees(struct tree *head,
1528                        struct tree *merge,
1529                        struct tree *common,
1530                        const char *branch1,
1531                        const char *branch2,
1532                        struct tree **result)
1533 {
1534         int code, clean;
1535
1536         if (subtree_merge) {
1537                 merge = shift_tree_object(head, merge);
1538                 common = shift_tree_object(head, common);
1539         }
1540
1541         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1542                 output(0, "Already uptodate!");
1543                 *result = head;
1544                 return 1;
1545         }
1546
1547         code = git_merge_trees(index_only, common, head, merge);
1548
1549         if (code != 0)
1550                 die("merging of trees %s and %s failed",
1551                     sha1_to_hex(head->object.sha1),
1552                     sha1_to_hex(merge->object.sha1));
1553
1554         if (unmerged_index()) {
1555                 struct path_list *entries, *re_head, *re_merge;
1556                 int i;
1557                 path_list_clear(&current_file_set, 1);
1558                 path_list_clear(&current_directory_set, 1);
1559                 get_files_dirs(head);
1560                 get_files_dirs(merge);
1561
1562                 entries = get_unmerged();
1563                 re_head  = get_renames(head, common, head, merge, entries);
1564                 re_merge = get_renames(merge, common, head, merge, entries);
1565                 clean = process_renames(re_head, re_merge,
1566                                 branch1, branch2);
1567                 for (i = 0; i < entries->nr; i++) {
1568                         const char *path = entries->items[i].path;
1569                         struct stage_data *e = entries->items[i].util;
1570                         if (!e->processed
1571                                 && !process_entry(path, e, branch1, branch2))
1572                                 clean = 0;
1573                 }
1574
1575                 path_list_clear(re_merge, 0);
1576                 path_list_clear(re_head, 0);
1577                 path_list_clear(entries, 1);
1578
1579         }
1580         else
1581                 clean = 1;
1582
1583         if (index_only)
1584                 *result = git_write_tree();
1585
1586         return clean;
1587 }
1588
1589 static struct commit_list *reverse_commit_list(struct commit_list *list)
1590 {
1591         struct commit_list *next = NULL, *current, *backup;
1592         for (current = list; current; current = backup) {
1593                 backup = current->next;
1594                 current->next = next;
1595                 next = current;
1596         }
1597         return next;
1598 }
1599
1600 /*
1601  * Merge the commits h1 and h2, return the resulting virtual
1602  * commit object and a flag indicating the cleanness of the merge.
1603  */
1604 static int merge(struct commit *h1,
1605                  struct commit *h2,
1606                  const char *branch1,
1607                  const char *branch2,
1608                  struct commit_list *ca,
1609                  struct commit **result)
1610 {
1611         struct commit_list *iter;
1612         struct commit *merged_common_ancestors;
1613         struct tree *mrtree;
1614         int clean;
1615
1616         if (show(4)) {
1617                 output(4, "Merging:");
1618                 output_commit_title(h1);
1619                 output_commit_title(h2);
1620         }
1621
1622         if (!ca) {
1623                 ca = get_merge_bases(h1, h2, 1);
1624                 ca = reverse_commit_list(ca);
1625         }
1626
1627         if (show(5)) {
1628                 output(5, "found %u common ancestor(s):", commit_list_count(ca));
1629                 for (iter = ca; iter; iter = iter->next)
1630                         output_commit_title(iter->item);
1631         }
1632
1633         merged_common_ancestors = pop_commit(&ca);
1634         if (merged_common_ancestors == NULL) {
1635                 /* if there is no common ancestor, make an empty tree */
1636                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1637
1638                 tree->object.parsed = 1;
1639                 tree->object.type = OBJ_TREE;
1640                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1641                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1642         }
1643
1644         for (iter = ca; iter; iter = iter->next) {
1645                 call_depth++;
1646                 /*
1647                  * When the merge fails, the result contains files
1648                  * with conflict markers. The cleanness flag is
1649                  * ignored, it was never actually used, as result of
1650                  * merge_trees has always overwritten it: the committed
1651                  * "conflicts" were already resolved.
1652                  */
1653                 discard_cache();
1654                 merge(merged_common_ancestors, iter->item,
1655                       "Temporary merge branch 1",
1656                       "Temporary merge branch 2",
1657                       NULL,
1658                       &merged_common_ancestors);
1659                 call_depth--;
1660
1661                 if (!merged_common_ancestors)
1662                         die("merge returned no commit");
1663         }
1664
1665         discard_cache();
1666         if (!call_depth) {
1667                 read_cache();
1668                 index_only = 0;
1669         } else
1670                 index_only = 1;
1671
1672         clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
1673                             branch1, branch2, &mrtree);
1674
1675         if (index_only) {
1676                 *result = make_virtual_commit(mrtree, "merged tree");
1677                 commit_list_insert(h1, &(*result)->parents);
1678                 commit_list_insert(h2, &(*result)->parents->next);
1679         }
1680         flush_output();
1681         return clean;
1682 }
1683
1684 static const char *better_branch_name(const char *branch)
1685 {
1686         static char githead_env[8 + 40 + 1];
1687         char *name;
1688
1689         if (strlen(branch) != 40)
1690                 return branch;
1691         sprintf(githead_env, "GITHEAD_%s", branch);
1692         name = getenv(githead_env);
1693         return name ? name : branch;
1694 }
1695
1696 static struct commit *get_ref(const char *ref)
1697 {
1698         unsigned char sha1[20];
1699         struct object *object;
1700
1701         if (get_sha1(ref, sha1))
1702                 die("Could not resolve ref '%s'", ref);
1703         object = deref_tag(parse_object(sha1), ref, strlen(ref));
1704         if (object->type == OBJ_TREE)
1705                 return make_virtual_commit((struct tree*)object,
1706                         better_branch_name(ref));
1707         if (object->type != OBJ_COMMIT)
1708                 return NULL;
1709         if (parse_commit((struct commit *)object))
1710                 die("Could not parse commit '%s'", sha1_to_hex(object->sha1));
1711         return (struct commit *)object;
1712 }
1713
1714 static int merge_config(const char *var, const char *value)
1715 {
1716         if (!strcasecmp(var, "merge.verbosity")) {
1717                 verbosity = git_config_int(var, value);
1718                 return 0;
1719         }
1720         return git_default_config(var, value);
1721 }
1722
1723 int main(int argc, char *argv[])
1724 {
1725         static const char *bases[20];
1726         static unsigned bases_count = 0;
1727         int i, clean;
1728         const char *branch1, *branch2;
1729         struct commit *result, *h1, *h2;
1730         struct commit_list *ca = NULL;
1731         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1732         int index_fd;
1733
1734         if (argv[0]) {
1735                 int namelen = strlen(argv[0]);
1736                 if (8 < namelen &&
1737                     !strcmp(argv[0] + namelen - 8, "-subtree"))
1738                         subtree_merge = 1;
1739         }
1740
1741         git_config(merge_config);
1742         if (getenv("GIT_MERGE_VERBOSITY"))
1743                 verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1744
1745         if (argc < 4)
1746                 die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
1747
1748         for (i = 1; i < argc; ++i) {
1749                 if (!strcmp(argv[i], "--"))
1750                         break;
1751                 if (bases_count < sizeof(bases)/sizeof(*bases))
1752                         bases[bases_count++] = argv[i];
1753         }
1754         if (argc - i != 3) /* "--" "<head>" "<remote>" */
1755                 die("Not handling anything other than two heads merge.");
1756         if (verbosity >= 5)
1757                 buffer_output = 0;
1758
1759         branch1 = argv[++i];
1760         branch2 = argv[++i];
1761
1762         h1 = get_ref(branch1);
1763         h2 = get_ref(branch2);
1764
1765         branch1 = better_branch_name(branch1);
1766         branch2 = better_branch_name(branch2);
1767
1768         if (show(3))
1769                 printf("Merging %s with %s\n", branch1, branch2);
1770
1771         index_fd = hold_locked_index(lock, 1);
1772
1773         for (i = 0; i < bases_count; i++) {
1774                 struct commit *ancestor = get_ref(bases[i]);
1775                 ca = commit_list_insert(ancestor, &ca);
1776         }
1777         clean = merge(h1, h2, branch1, branch2, ca, &result);
1778
1779         if (active_cache_changed &&
1780             (write_cache(index_fd, active_cache, active_nr) ||
1781              close(index_fd) || commit_locked_index(lock)))
1782                         die ("unable to write %s", get_index_file());
1783
1784         return clean ? 0: 1;
1785 }