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