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