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         const char *recursive;
 681         struct ll_merge_driver *next;
 682         char *cmdline;
 683 };
 684
 685 /*
 686  * Built-in low-levels
 687  */
 688 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 689                         const char *path_unused,
 690                         mmfile_t *orig,
 691                         mmfile_t *src1, const char *name1,
 692                         mmfile_t *src2, const char *name2,
 693                         mmbuffer_t *result)
 694 {
 695         xpparam_t xpp;
 696
 697         memset(&xpp, 0, sizeof(xpp));
 698         return xdl_merge(orig,
 699                          src1, name1,
 700                          src2, name2,
 701                          &xpp, XDL_MERGE_ZEALOUS,
 702                          result);
 703 }
 704
 705 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 706                           const char *path_unused,
 707                           mmfile_t *orig,
 708                           mmfile_t *src1, const char *name1,
 709                           mmfile_t *src2, const char *name2,
 710                           mmbuffer_t *result)
 711 {
 712         char *src, *dst;
 713         long size;
 714         const int marker_size = 7;
 715
 716         int status = ll_xdl_merge(drv_unused, path_unused,
 717                                   orig, src1, NULL, src2, NULL, result);
 718         if (status <= 0)
 719                 return status;
 720         size = result->size;
 721         src = dst = result->ptr;
 722         while (size) {
 723                 char ch;
 724                 if ((marker_size < size) &&
 725                     (*src == '<' || *src == '=' || *src == '>')) {
 726                         int i;
 727                         ch = *src;
 728                         for (i = 0; i < marker_size; i++)
 729                                 if (src[i] != ch)
 730                                         goto not_a_marker;
 731                         if (src[marker_size] != '\n')
 732                                 goto not_a_marker;
 733                         src += marker_size + 1;
 734                         size -= marker_size + 1;
 735                         continue;
 736                 }
 737         not_a_marker:
 738                 do {
 739                         ch = *src++;
 740                         *dst++ = ch;
 741                         size--;
 742                 } while (ch != '\n' && size);
 743         }
 744         result->size = dst - result->ptr;
 745         return 0;
 746 }
 747
 748 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 749                            const char *path_unused,
 750                            mmfile_t *orig,
 751                            mmfile_t *src1, const char *name1,
 752                            mmfile_t *src2, const char *name2,
 753                            mmbuffer_t *result)
 754 {
 755         /*
 756          * The tentative merge result is "ours" for the final round,
 757          * or common ancestor for an internal merge.  Still return
 758          * "conflicted merge" status.
 759          */
 760         mmfile_t *stolen = index_only ? orig : src1;
 761
 762         result->ptr = stolen->ptr;
 763         result->size = stolen->size;
 764         stolen->ptr = NULL;
 765         return 1;
 766 }
 767
 768 #define LL_BINARY_MERGE 0
 769 #define LL_TEXT_MERGE 1
 770 #define LL_UNION_MERGE 2
 771 static struct ll_merge_driver ll_merge_drv[] = {
 772         { "binary", "built-in binary merge", ll_binary_merge },
 773         { "text", "built-in 3-way text merge", ll_xdl_merge },
 774         { "union", "built-in union merge", ll_union_merge },
 775 };
 776
 777 static void create_temp(mmfile_t *src, char *path)
 778 {
 779         int fd;
 780
 781         strcpy(path, ".merge_file_XXXXXX");
 782         fd = mkstemp(path);
 783         if (fd < 0)
 784                 die("unable to create temp-file");
 785         if (write_in_full(fd, src->ptr, src->size) != src->size)
 786                 die("unable to write temp-file");
 787         close(fd);
 788 }
 789
 790 /*
 791  * User defined low-level merge driver support.
 792  */
 793 static int ll_ext_merge(const struct ll_merge_driver *fn,
 794                         const char *path,
 795                         mmfile_t *orig,
 796                         mmfile_t *src1, const char *name1,
 797                         mmfile_t *src2, const char *name2,
 798                         mmbuffer_t *result)
 799 {
 800         char temp[3][50];
 801         char cmdbuf[2048];
 802         struct interp table[] = {
 803                 { "%O" },
 804                 { "%A" },
 805                 { "%B" },
 806         };
 807         struct child_process child;
 808         const char *args[20];
 809         int status, fd, i;
 810         struct stat st;
 811
 812         if (fn->cmdline == NULL)
 813                 die("custom merge driver %s lacks command line.", fn->name);
 814
 815         result->ptr = NULL;
 816         result->size = 0;
 817         create_temp(orig, temp[0]);
 818         create_temp(src1, temp[1]);
 819         create_temp(src2, temp[2]);
 820
 821         interp_set_entry(table, 0, temp[0]);
 822         interp_set_entry(table, 1, temp[1]);
 823         interp_set_entry(table, 2, temp[2]);
 824
 825         output(1, "merging %s using %s", path,
 826                fn->description ? fn->description : fn->name);
 827
 828         interpolate(cmdbuf, sizeof(cmdbuf), fn->cmdline, table, 3);
 829
 830         memset(&child, 0, sizeof(child));
 831         child.argv = args;
 832         args[0] = "sh";
 833         args[1] = "-c";
 834         args[2] = cmdbuf;
 835         args[3] = NULL;
 836
 837         status = run_command(&child);
 838         if (status < -ERR_RUN_COMMAND_FORK)
 839                 ; /* failure in run-command */
 840         else
 841                 status = -status;
 842         fd = open(temp[1], O_RDONLY);
 843         if (fd < 0)
 844                 goto bad;
 845         if (fstat(fd, &st))
 846                 goto close_bad;
 847         result->size = st.st_size;
 848         result->ptr = xmalloc(result->size + 1);
 849         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 850                 free(result->ptr);
 851                 result->ptr = NULL;
 852                 result->size = 0;
 853         }
 854  close_bad:
 855         close(fd);
 856  bad:
 857         for (i = 0; i < 3; i++)
 858                 unlink(temp[i]);
 859         return status;
 860 }
 861
 862 /*
 863  * merge.default and merge.driver configuration items
 864  */
 865 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 866 static const char *default_ll_merge;
 867
 868 static int read_merge_config(const char *var, const char *value)
 869 {
 870         struct ll_merge_driver *fn;
 871         const char *ep, *name;
 872         int namelen;
 873
 874         if (!strcmp(var, "merge.default")) {
 875                 if (value)
 876                         default_ll_merge = strdup(value);
 877                 return 0;
 878         }
 879
 880         /*
 881          * We are not interested in anything but "merge.<name>.variable";
 882          * especially, we do not want to look at variables such as
 883          * "merge.summary", "merge.tool", and "merge.verbosity".
 884          */
 885         if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
 886                 return 0;
 887
 888         /*
 889          * Find existing one as we might be processing merge.<name>.var2
 890          * after seeing merge.<name>.var1.
 891          */
 892         name = var + 6;
 893         namelen = ep - name;
 894         for (fn = ll_user_merge; fn; fn = fn->next)
 895                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 896                         break;
 897         if (!fn) {
 898                 char *namebuf;
 899                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
 900                 namebuf = xmalloc(namelen + 1);
 901                 memcpy(namebuf, name, namelen);
 902                 namebuf[namelen] = 0;
 903                 fn->name = namebuf;
 904                 fn->fn = ll_ext_merge;
 905                 fn->next = *ll_user_merge_tail;
 906                 *ll_user_merge_tail = fn;
 907         }
 908
 909         ep++;
 910
 911         if (!strcmp("name", ep)) {
 912                 if (!value)
 913                         return error("%s: lacks value", var);
 914                 fn->description = strdup(value);
 915                 return 0;
 916         }
 917
 918         if (!strcmp("driver", ep)) {
 919                 if (!value)
 920                         return error("%s: lacks value", var);
 921                 /*
 922                  * merge.<name>.driver specifies the command line:
 923                  *
 924                  *      command-line
 925                  *
 926                  * The command-line will be interpolated with the following
 927                  * tokens and is given to the shell:
 928                  *
 929                  *    %O - temporary file name for the merge base.
 930                  *    %A - temporary file name for our version.
 931                  *    %B - temporary file name for the other branches' version.
 932                  *
 933                  * The external merge driver should write the results in the
 934                  * file named by %A, and signal that it has done with zero exit
 935                  * status.
 936                  */
 937                 fn->cmdline = strdup(value);
 938                 return 0;
 939         }
 940
 941         if (!strcmp("recursive", ep)) {
 942                 if (!value)
 943                         return error("%s: lacks value", var);
 944                 fn->recursive = strdup(value);
 945                 return 0;
 946         }
 947
 948         return 0;
 949 }
 950
 951 static void initialize_ll_merge(void)
 952 {
 953         if (ll_user_merge_tail)
 954                 return;
 955         ll_user_merge_tail = &ll_user_merge;
 956         git_config(read_merge_config);
 957 }
 958
 959 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 960 {
 961         struct ll_merge_driver *fn;
 962         const char *name;
 963         int i;
 964
 965         initialize_ll_merge();
 966
 967         if (ATTR_TRUE(merge_attr))
 968                 return &ll_merge_drv[LL_TEXT_MERGE];
 969         else if (ATTR_FALSE(merge_attr))
 970                 return &ll_merge_drv[LL_BINARY_MERGE];
 971         else if (ATTR_UNSET(merge_attr)) {
 972                 if (!default_ll_merge)
 973                         return &ll_merge_drv[LL_TEXT_MERGE];
 974                 else
 975                         name = default_ll_merge;
 976         }
 977         else
 978                 name = merge_attr;
 979
 980         for (fn = ll_user_merge; fn; fn = fn->next)
 981                 if (!strcmp(fn->name, name))
 982                         return fn;
 983
 984         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 985                 if (!strcmp(ll_merge_drv[i].name, name))
 986                         return &ll_merge_drv[i];
 987
 988         /* default to the 3-way */
 989         return &ll_merge_drv[LL_TEXT_MERGE];
 990 }
 991
 992 static const char *git_path_check_merge(const char *path)
 993 {
 994         static struct git_attr_check attr_merge_check;
 995
 996         if (!attr_merge_check.attr)
 997                 attr_merge_check.attr = git_attr("merge", 5);
 998
 999         if (git_checkattr(path, 1, &attr_merge_check))
1000                 return NULL;
1001         return attr_merge_check.value;
1002 }
1003
1004 static int ll_merge(mmbuffer_t *result_buf,
1005                     struct diff_filespec *o,
1006                     struct diff_filespec *a,
1007                     struct diff_filespec *b,
1008                     const char *branch1,
1009                     const char *branch2)
1010 {
1011         mmfile_t orig, src1, src2;
1012         char *name1, *name2;
1013         int merge_status;
1014         const char *ll_driver_name;
1015         const struct ll_merge_driver *driver;
1016
1017         name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
1018         name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
1019
1020         fill_mm(o->sha1, &orig);
1021         fill_mm(a->sha1, &src1);
1022         fill_mm(b->sha1, &src2);
1023
1024         ll_driver_name = git_path_check_merge(a->path);
1025         driver = find_ll_merge_driver(ll_driver_name);
1026
1027         if (index_only && driver->recursive) {
1028                 void *merge_attr;
1029
1030                 ll_driver_name = driver->recursive;
1031                 merge_attr = git_attr(ll_driver_name, strlen(ll_driver_name));
1032                 driver = find_ll_merge_driver(merge_attr);
1033         }
1034         merge_status = driver->fn(driver, a->path,
1035                                   &orig, &src1, name1, &src2, name2,
1036                                   result_buf);
1037
1038         free(name1);
1039         free(name2);
1040         free(orig.ptr);
1041         free(src1.ptr);
1042         free(src2.ptr);
1043         return merge_status;
1044 }
1045
1046 static struct merge_file_info merge_file(struct diff_filespec *o,
1047                 struct diff_filespec *a, struct diff_filespec *b,
1048                 const char *branch1, const char *branch2)
1049 {
1050         struct merge_file_info result;
1051         result.merge = 0;
1052         result.clean = 1;
1053
1054         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
1055                 result.clean = 0;
1056                 if (S_ISREG(a->mode)) {
1057                         result.mode = a->mode;
1058                         hashcpy(result.sha, a->sha1);
1059                 } else {
1060                         result.mode = b->mode;
1061                         hashcpy(result.sha, b->sha1);
1062                 }
1063         } else {
1064                 if (!sha_eq(a->sha1, o->sha1) && !sha_eq(b->sha1, o->sha1))
1065                         result.merge = 1;
1066
1067                 result.mode = a->mode == o->mode ? b->mode: a->mode;
1068
1069                 if (sha_eq(a->sha1, o->sha1))
1070                         hashcpy(result.sha, b->sha1);
1071                 else if (sha_eq(b->sha1, o->sha1))
1072                         hashcpy(result.sha, a->sha1);
1073                 else if (S_ISREG(a->mode)) {
1074                         mmbuffer_t result_buf;
1075                         int merge_status;
1076
1077                         merge_status = ll_merge(&result_buf, o, a, b,
1078                                                 branch1, branch2);
1079
1080                         if ((merge_status < 0) || !result_buf.ptr)
1081                                 die("Failed to execute internal merge");
1082
1083                         if (write_sha1_file(result_buf.ptr, result_buf.size,
1084                                             blob_type, result.sha))
1085                                 die("Unable to add %s to database",
1086                                     a->path);
1087
1088                         free(result_buf.ptr);
1089                         result.clean = (merge_status == 0);
1090                 } else {
1091                         if (!(S_ISLNK(a->mode) || S_ISLNK(b->mode)))
1092                                 die("cannot merge modes?");
1093
1094                         hashcpy(result.sha, a->sha1);
1095
1096                         if (!sha_eq(a->sha1, b->sha1))
1097                                 result.clean = 0;
1098                 }
1099         }
1100
1101         return result;
1102 }
1103
1104 static void conflict_rename_rename(struct rename *ren1,
1105                                    const char *branch1,
1106                                    struct rename *ren2,
1107                                    const char *branch2)
1108 {
1109         char *del[2];
1110         int delp = 0;
1111         const char *ren1_dst = ren1->pair->two->path;
1112         const char *ren2_dst = ren2->pair->two->path;
1113         const char *dst_name1 = ren1_dst;
1114         const char *dst_name2 = ren2_dst;
1115         if (path_list_has_path(&current_directory_set, ren1_dst)) {
1116                 dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
1117                 output(1, "%s is a directory in %s added as %s instead",
1118                        ren1_dst, branch2, dst_name1);
1119                 remove_file(0, ren1_dst, 0);
1120         }
1121         if (path_list_has_path(&current_directory_set, ren2_dst)) {
1122                 dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
1123                 output(1, "%s is a directory in %s added as %s instead",
1124                        ren2_dst, branch1, dst_name2);
1125                 remove_file(0, ren2_dst, 0);
1126         }
1127         if (index_only) {
1128                 remove_file_from_cache(dst_name1);
1129                 remove_file_from_cache(dst_name2);
1130                 /*
1131                  * Uncomment to leave the conflicting names in the resulting tree
1132                  *
1133                  * update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
1134                  * update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
1135                  */
1136         } else {
1137                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
1138                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
1139         }
1140         while (delp--)
1141                 free(del[delp]);
1142 }
1143
1144 static void conflict_rename_dir(struct rename *ren1,
1145                                 const char *branch1)
1146 {
1147         char *new_path = unique_path(ren1->pair->two->path, branch1);
1148         output(1, "Renamed %s to %s instead", ren1->pair->one->path, new_path);
1149         remove_file(0, ren1->pair->two->path, 0);
1150         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
1151         free(new_path);
1152 }
1153
1154 static void conflict_rename_rename_2(struct rename *ren1,
1155                                      const char *branch1,
1156                                      struct rename *ren2,
1157                                      const char *branch2)
1158 {
1159         char *new_path1 = unique_path(ren1->pair->two->path, branch1);
1160         char *new_path2 = unique_path(ren2->pair->two->path, branch2);
1161         output(1, "Renamed %s to %s and %s to %s instead",
1162                ren1->pair->one->path, new_path1,
1163                ren2->pair->one->path, new_path2);
1164         remove_file(0, ren1->pair->two->path, 0);
1165         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
1166         update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
1167         free(new_path2);
1168         free(new_path1);
1169 }
1170
1171 static int process_renames(struct path_list *a_renames,
1172                            struct path_list *b_renames,
1173                            const char *a_branch,
1174                            const char *b_branch)
1175 {
1176         int clean_merge = 1, i, j;
1177         struct path_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
1178         const struct rename *sre;
1179
1180         for (i = 0; i < a_renames->nr; i++) {
1181                 sre = a_renames->items[i].util;
1182                 path_list_insert(sre->pair->two->path, &a_by_dst)->util
1183                         = sre->dst_entry;
1184         }
1185         for (i = 0; i < b_renames->nr; i++) {
1186                 sre = b_renames->items[i].util;
1187                 path_list_insert(sre->pair->two->path, &b_by_dst)->util
1188                         = sre->dst_entry;
1189         }
1190
1191         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
1192                 int compare;
1193                 char *src;
1194                 struct path_list *renames1, *renames2, *renames2Dst;
1195                 struct rename *ren1 = NULL, *ren2 = NULL;
1196                 const char *branch1, *branch2;
1197                 const char *ren1_src, *ren1_dst;
1198
1199                 if (i >= a_renames->nr) {
1200                         compare = 1;
1201                         ren2 = b_renames->items[j++].util;
1202                 } else if (j >= b_renames->nr) {
1203                         compare = -1;
1204                         ren1 = a_renames->items[i++].util;
1205                 } else {
1206                         compare = strcmp(a_renames->items[i].path,
1207                                         b_renames->items[j].path);
1208                         if (compare <= 0)
1209                                 ren1 = a_renames->items[i++].util;
1210                         if (compare >= 0)
1211                                 ren2 = b_renames->items[j++].util;
1212                 }
1213
1214                 /* TODO: refactor, so that 1/2 are not needed */
1215                 if (ren1) {
1216                         renames1 = a_renames;
1217                         renames2 = b_renames;
1218                         renames2Dst = &b_by_dst;
1219                         branch1 = a_branch;
1220                         branch2 = b_branch;
1221                 } else {
1222                         struct rename *tmp;
1223                         renames1 = b_renames;
1224                         renames2 = a_renames;
1225                         renames2Dst = &a_by_dst;
1226                         branch1 = b_branch;
1227                         branch2 = a_branch;
1228                         tmp = ren2;
1229                         ren2 = ren1;
1230                         ren1 = tmp;
1231                 }
1232                 src = ren1->pair->one->path;
1233
1234                 ren1->dst_entry->processed = 1;
1235                 ren1->src_entry->processed = 1;
1236
1237                 if (ren1->processed)
1238                         continue;
1239                 ren1->processed = 1;
1240
1241                 ren1_src = ren1->pair->one->path;
1242                 ren1_dst = ren1->pair->two->path;
1243
1244                 if (ren2) {
1245                         const char *ren2_src = ren2->pair->one->path;
1246                         const char *ren2_dst = ren2->pair->two->path;
1247                         /* Renamed in 1 and renamed in 2 */
1248                         if (strcmp(ren1_src, ren2_src) != 0)
1249                                 die("ren1.src != ren2.src");
1250                         ren2->dst_entry->processed = 1;
1251                         ren2->processed = 1;
1252                         if (strcmp(ren1_dst, ren2_dst) != 0) {
1253                                 clean_merge = 0;
1254                                 output(1, "CONFLICT (rename/rename): "
1255                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
1256                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
1257                                        src, ren1_dst, branch1,
1258                                        src, ren2_dst, branch2,
1259                                        index_only ? " (left unresolved)": "");
1260                                 if (index_only) {
1261                                         remove_file_from_cache(src);
1262                                         update_file(0, ren1->pair->one->sha1,
1263                                                     ren1->pair->one->mode, src);
1264                                 }
1265                                 conflict_rename_rename(ren1, branch1, ren2, branch2);
1266                         } else {
1267                                 struct merge_file_info mfi;
1268                                 remove_file(1, ren1_src, 1);
1269                                 mfi = merge_file(ren1->pair->one,
1270                                                  ren1->pair->two,
1271                                                  ren2->pair->two,
1272                                                  branch1,
1273                                                  branch2);
1274                                 if (mfi.merge || !mfi.clean)
1275                                         output(1, "Renamed %s->%s", src, ren1_dst);
1276
1277                                 if (mfi.merge)
1278                                         output(2, "Auto-merged %s", ren1_dst);
1279
1280                                 if (!mfi.clean) {
1281                                         output(1, "CONFLICT (content): merge conflict in %s",
1282                                                ren1_dst);
1283                                         clean_merge = 0;
1284
1285                                         if (!index_only)
1286                                                 update_stages(ren1_dst,
1287                                                               ren1->pair->one,
1288                                                               ren1->pair->two,
1289                                                               ren2->pair->two,
1290                                                               1 /* clear */);
1291                                 }
1292                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1293                         }
1294                 } else {
1295                         /* Renamed in 1, maybe changed in 2 */
1296                         struct path_list_item *item;
1297                         /* we only use sha1 and mode of these */
1298                         struct diff_filespec src_other, dst_other;
1299                         int try_merge, stage = a_renames == renames1 ? 3: 2;
1300
1301                         remove_file(1, ren1_src, index_only || stage == 3);
1302
1303                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
1304                         src_other.mode = ren1->src_entry->stages[stage].mode;
1305                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
1306                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
1307
1308                         try_merge = 0;
1309
1310                         if (path_list_has_path(&current_directory_set, ren1_dst)) {
1311                                 clean_merge = 0;
1312                                 output(1, "CONFLICT (rename/directory): Renamed %s->%s in %s "
1313                                        " directory %s added in %s",
1314                                        ren1_src, ren1_dst, branch1,
1315                                        ren1_dst, branch2);
1316                                 conflict_rename_dir(ren1, branch1);
1317                         } else if (sha_eq(src_other.sha1, null_sha1)) {
1318                                 clean_merge = 0;
1319                                 output(1, "CONFLICT (rename/delete): Renamed %s->%s in %s "
1320                                        "and deleted in %s",
1321                                        ren1_src, ren1_dst, branch1,
1322                                        branch2);
1323                                 update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
1324                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
1325                                 const char *new_path;
1326                                 clean_merge = 0;
1327                                 try_merge = 1;
1328                                 output(1, "CONFLICT (rename/add): Renamed %s->%s in %s. "
1329                                        "%s added in %s",
1330                                        ren1_src, ren1_dst, branch1,
1331                                        ren1_dst, branch2);
1332                                 new_path = unique_path(ren1_dst, branch2);
1333                                 output(1, "Added as %s instead", new_path);
1334                                 update_file(0, dst_other.sha1, dst_other.mode, new_path);
1335                         } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
1336                                 ren2 = item->util;
1337                                 clean_merge = 0;
1338                                 ren2->processed = 1;
1339                                 output(1, "CONFLICT (rename/rename): Renamed %s->%s in %s. "
1340                                        "Renamed %s->%s in %s",
1341                                        ren1_src, ren1_dst, branch1,
1342                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
1343                                 conflict_rename_rename_2(ren1, branch1, ren2, branch2);
1344                         } else
1345                                 try_merge = 1;
1346
1347                         if (try_merge) {
1348                                 struct diff_filespec *o, *a, *b;
1349                                 struct merge_file_info mfi;
1350                                 src_other.path = (char *)ren1_src;
1351
1352                                 o = ren1->pair->one;
1353                                 if (a_renames == renames1) {
1354                                         a = ren1->pair->two;
1355                                         b = &src_other;
1356                                 } else {
1357                                         b = ren1->pair->two;
1358                                         a = &src_other;
1359                                 }
1360                                 mfi = merge_file(o, a, b,
1361                                                 a_branch, b_branch);
1362
1363                                 if (mfi.merge || !mfi.clean)
1364                                         output(1, "Renamed %s => %s", ren1_src, ren1_dst);
1365                                 if (mfi.merge)
1366                                         output(2, "Auto-merged %s", ren1_dst);
1367                                 if (!mfi.clean) {
1368                                         output(1, "CONFLICT (rename/modify): Merge conflict in %s",
1369                                                ren1_dst);
1370                                         clean_merge = 0;
1371
1372                                         if (!index_only)
1373                                                 update_stages(ren1_dst,
1374                                                                 o, a, b, 1);
1375                                 }
1376                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1377                         }
1378                 }
1379         }
1380         path_list_clear(&a_by_dst, 0);
1381         path_list_clear(&b_by_dst, 0);
1382
1383         return clean_merge;
1384 }
1385
1386 static unsigned char *has_sha(const unsigned char *sha)
1387 {
1388         return is_null_sha1(sha) ? NULL: (unsigned char *)sha;
1389 }
1390
1391 /* Per entry merge function */
1392 static int process_entry(const char *path, struct stage_data *entry,
1393                          const char *branch1,
1394                          const char *branch2)
1395 {
1396         /*
1397         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1398         print_index_entry("\tpath: ", entry);
1399         */
1400         int clean_merge = 1;
1401         unsigned char *o_sha = has_sha(entry->stages[1].sha);
1402         unsigned char *a_sha = has_sha(entry->stages[2].sha);
1403         unsigned char *b_sha = has_sha(entry->stages[3].sha);
1404         unsigned o_mode = entry->stages[1].mode;
1405         unsigned a_mode = entry->stages[2].mode;
1406         unsigned b_mode = entry->stages[3].mode;
1407
1408         if (o_sha && (!a_sha || !b_sha)) {
1409                 /* Case A: Deleted in one */
1410                 if ((!a_sha && !b_sha) ||
1411                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1412                     (!a_sha && sha_eq(b_sha, o_sha))) {
1413                         /* Deleted in both or deleted in one and
1414                          * unchanged in the other */
1415                         if (a_sha)
1416                                 output(2, "Removed %s", path);
1417                         /* do not touch working file if it did not exist */
1418                         remove_file(1, path, !a_sha);
1419                 } else {
1420                         /* Deleted in one and changed in the other */
1421                         clean_merge = 0;
1422                         if (!a_sha) {
1423                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1424                                        "and modified in %s. Version %s of %s left in tree.",
1425                                        path, branch1,
1426                                        branch2, branch2, path);
1427                                 update_file(0, b_sha, b_mode, path);
1428                         } else {
1429                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1430                                        "and modified in %s. Version %s of %s left in tree.",
1431                                        path, branch2,
1432                                        branch1, branch1, path);
1433                                 update_file(0, a_sha, a_mode, path);
1434                         }
1435                 }
1436
1437         } else if ((!o_sha && a_sha && !b_sha) ||
1438                    (!o_sha && !a_sha && b_sha)) {
1439                 /* Case B: Added in one. */
1440                 const char *add_branch;
1441                 const char *other_branch;
1442                 unsigned mode;
1443                 const unsigned char *sha;
1444                 const char *conf;
1445
1446                 if (a_sha) {
1447                         add_branch = branch1;
1448                         other_branch = branch2;
1449                         mode = a_mode;
1450                         sha = a_sha;
1451                         conf = "file/directory";
1452                 } else {
1453                         add_branch = branch2;
1454                         other_branch = branch1;
1455                         mode = b_mode;
1456                         sha = b_sha;
1457                         conf = "directory/file";
1458                 }
1459                 if (path_list_has_path(&current_directory_set, path)) {
1460                         const char *new_path = unique_path(path, add_branch);
1461                         clean_merge = 0;
1462                         output(1, "CONFLICT (%s): There is a directory with name %s in %s. "
1463                                "Added %s as %s",
1464                                conf, path, other_branch, path, new_path);
1465                         remove_file(0, path, 0);
1466                         update_file(0, sha, mode, new_path);
1467                 } else {
1468                         output(2, "Added %s", path);
1469                         update_file(1, sha, mode, path);
1470                 }
1471         } else if (a_sha && b_sha) {
1472                 /* Case C: Added in both (check for same permissions) and */
1473                 /* case D: Modified in both, but differently. */
1474                 const char *reason = "content";
1475                 struct merge_file_info mfi;
1476                 struct diff_filespec o, a, b;
1477
1478                 if (!o_sha) {
1479                         reason = "add/add";
1480                         o_sha = (unsigned char *)null_sha1;
1481                 }
1482                 output(2, "Auto-merged %s", path);
1483                 o.path = a.path = b.path = (char *)path;
1484                 hashcpy(o.sha1, o_sha);
1485                 o.mode = o_mode;
1486                 hashcpy(a.sha1, a_sha);
1487                 a.mode = a_mode;
1488                 hashcpy(b.sha1, b_sha);
1489                 b.mode = b_mode;
1490
1491                 mfi = merge_file(&o, &a, &b,
1492                                  branch1, branch2);
1493
1494                 if (mfi.clean)
1495                         update_file(1, mfi.sha, mfi.mode, path);
1496                 else {
1497                         clean_merge = 0;
1498                         output(1, "CONFLICT (%s): Merge conflict in %s",
1499                                         reason, path);
1500
1501                         if (index_only)
1502                                 update_file(0, mfi.sha, mfi.mode, path);
1503                         else
1504                                 update_file_flags(mfi.sha, mfi.mode, path,
1505                                               0 /* update_cache */, 1 /* update_working_directory */);
1506                 }
1507         } else
1508                 die("Fatal merge failure, shouldn't happen.");
1509
1510         return clean_merge;
1511 }
1512
1513 static int merge_trees(struct tree *head,
1514                        struct tree *merge,
1515                        struct tree *common,
1516                        const char *branch1,
1517                        const char *branch2,
1518                        struct tree **result)
1519 {
1520         int code, clean;
1521
1522         if (subtree_merge) {
1523                 merge = shift_tree_object(head, merge);
1524                 common = shift_tree_object(head, common);
1525         }
1526
1527         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1528                 output(0, "Already uptodate!");
1529                 *result = head;
1530                 return 1;
1531         }
1532
1533         code = git_merge_trees(index_only, common, head, merge);
1534
1535         if (code != 0)
1536                 die("merging of trees %s and %s failed",
1537                     sha1_to_hex(head->object.sha1),
1538                     sha1_to_hex(merge->object.sha1));
1539
1540         if (unmerged_index()) {
1541                 struct path_list *entries, *re_head, *re_merge;
1542                 int i;
1543                 path_list_clear(&current_file_set, 1);
1544                 path_list_clear(&current_directory_set, 1);
1545                 get_files_dirs(head);
1546                 get_files_dirs(merge);
1547
1548                 entries = get_unmerged();
1549                 re_head  = get_renames(head, common, head, merge, entries);
1550                 re_merge = get_renames(merge, common, head, merge, entries);
1551                 clean = process_renames(re_head, re_merge,
1552                                 branch1, branch2);
1553                 total_cnt += entries->nr;
1554                 for (i = 0; i < entries->nr; i++, merged_cnt++) {
1555                         const char *path = entries->items[i].path;
1556                         struct stage_data *e = entries->items[i].util;
1557                         if (!e->processed
1558                                 && !process_entry(path, e, branch1, branch2))
1559                                 clean = 0;
1560                         if (do_progress)
1561                                 display_progress();
1562                 }
1563
1564                 path_list_clear(re_merge, 0);
1565                 path_list_clear(re_head, 0);
1566                 path_list_clear(entries, 1);
1567
1568         }
1569         else
1570                 clean = 1;
1571
1572         if (index_only)
1573                 *result = git_write_tree();
1574
1575         return clean;
1576 }
1577
1578 static struct commit_list *reverse_commit_list(struct commit_list *list)
1579 {
1580         struct commit_list *next = NULL, *current, *backup;
1581         for (current = list; current; current = backup) {
1582                 backup = current->next;
1583                 current->next = next;
1584                 next = current;
1585         }
1586         return next;
1587 }
1588
1589 /*
1590  * Merge the commits h1 and h2, return the resulting virtual
1591  * commit object and a flag indicating the cleanness of the merge.
1592  */
1593 static int merge(struct commit *h1,
1594                  struct commit *h2,
1595                  const char *branch1,
1596                  const char *branch2,
1597                  struct commit_list *ca,
1598                  struct commit **result)
1599 {
1600         struct commit_list *iter;
1601         struct commit *merged_common_ancestors;
1602         struct tree *mrtree;
1603         int clean;
1604
1605         if (show(4)) {
1606                 output(4, "Merging:");
1607                 output_commit_title(h1);
1608                 output_commit_title(h2);
1609         }
1610
1611         if (!ca) {
1612                 ca = get_merge_bases(h1, h2, 1);
1613                 ca = reverse_commit_list(ca);
1614         }
1615
1616         if (show(5)) {
1617                 output(5, "found %u common ancestor(s):", commit_list_count(ca));
1618                 for (iter = ca; iter; iter = iter->next)
1619                         output_commit_title(iter->item);
1620         }
1621
1622         merged_common_ancestors = pop_commit(&ca);
1623         if (merged_common_ancestors == NULL) {
1624                 /* if there is no common ancestor, make an empty tree */
1625                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1626
1627                 tree->object.parsed = 1;
1628                 tree->object.type = OBJ_TREE;
1629                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1630                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1631         }
1632
1633         for (iter = ca; iter; iter = iter->next) {
1634                 call_depth++;
1635                 /*
1636                  * When the merge fails, the result contains files
1637                  * with conflict markers. The cleanness flag is
1638                  * ignored, it was never actually used, as result of
1639                  * merge_trees has always overwritten it: the committed
1640                  * "conflicts" were already resolved.
1641                  */
1642                 discard_cache();
1643                 merge(merged_common_ancestors, iter->item,
1644                       "Temporary merge branch 1",
1645                       "Temporary merge branch 2",
1646                       NULL,
1647                       &merged_common_ancestors);
1648                 call_depth--;
1649
1650                 if (!merged_common_ancestors)
1651                         die("merge returned no commit");
1652         }
1653
1654         discard_cache();
1655         if (!call_depth) {
1656                 read_cache();
1657                 index_only = 0;
1658         } else
1659                 index_only = 1;
1660
1661         clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
1662                             branch1, branch2, &mrtree);
1663
1664         if (index_only) {
1665                 *result = make_virtual_commit(mrtree, "merged tree");
1666                 commit_list_insert(h1, &(*result)->parents);
1667                 commit_list_insert(h2, &(*result)->parents->next);
1668         }
1669         if (!call_depth && do_progress) {
1670                 /* Make sure we end at 100% */
1671                 if (!total_cnt)
1672                         total_cnt = 1;
1673                 merged_cnt = total_cnt;
1674                 progress_update = 1;
1675                 display_progress();
1676                 fputc('\n', stderr);
1677         }
1678         flush_output();
1679         return clean;
1680 }
1681
1682 static const char *better_branch_name(const char *branch)
1683 {
1684         static char githead_env[8 + 40 + 1];
1685         char *name;
1686
1687         if (strlen(branch) != 40)
1688                 return branch;
1689         sprintf(githead_env, "GITHEAD_%s", branch);
1690         name = getenv(githead_env);
1691         return name ? name : branch;
1692 }
1693
1694 static struct commit *get_ref(const char *ref)
1695 {
1696         unsigned char sha1[20];
1697         struct object *object;
1698
1699         if (get_sha1(ref, sha1))
1700                 die("Could not resolve ref '%s'", ref);
1701         object = deref_tag(parse_object(sha1), ref, strlen(ref));
1702         if (object->type == OBJ_TREE)
1703                 return make_virtual_commit((struct tree*)object,
1704                         better_branch_name(ref));
1705         if (object->type != OBJ_COMMIT)
1706                 return NULL;
1707         if (parse_commit((struct commit *)object))
1708                 die("Could not parse commit '%s'", sha1_to_hex(object->sha1));
1709         return (struct commit *)object;
1710 }
1711
1712 static int merge_config(const char *var, const char *value)
1713 {
1714         if (!strcasecmp(var, "merge.verbosity")) {
1715                 verbosity = git_config_int(var, value);
1716                 return 0;
1717         }
1718         return git_default_config(var, value);
1719 }
1720
1721 int main(int argc, char *argv[])
1722 {
1723         static const char *bases[20];
1724         static unsigned bases_count = 0;
1725         int i, clean;
1726         const char *branch1, *branch2;
1727         struct commit *result, *h1, *h2;
1728         struct commit_list *ca = NULL;
1729         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1730         int index_fd;
1731
1732         if (argv[0]) {
1733                 int namelen = strlen(argv[0]);
1734                 if (8 < namelen &&
1735                     !strcmp(argv[0] + namelen - 8, "-subtree"))
1736                         subtree_merge = 1;
1737         }
1738
1739         git_config(merge_config);
1740         if (getenv("GIT_MERGE_VERBOSITY"))
1741                 verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1742
1743         if (argc < 4)
1744                 die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
1745
1746         for (i = 1; i < argc; ++i) {
1747                 if (!strcmp(argv[i], "--"))
1748                         break;
1749                 if (bases_count < sizeof(bases)/sizeof(*bases))
1750                         bases[bases_count++] = argv[i];
1751         }
1752         if (argc - i != 3) /* "--" "<head>" "<remote>" */
1753                 die("Not handling anything other than two heads merge.");
1754         if (verbosity >= 5) {
1755                 buffer_output = 0;
1756                 do_progress = 0;
1757         }
1758         else
1759                 do_progress = isatty(1);
1760
1761         branch1 = argv[++i];
1762         branch2 = argv[++i];
1763
1764         h1 = get_ref(branch1);
1765         h2 = get_ref(branch2);
1766
1767         branch1 = better_branch_name(branch1);
1768         branch2 = better_branch_name(branch2);
1769
1770         if (do_progress)
1771                 setup_progress_signal();
1772         if (show(3))
1773                 printf("Merging %s with %s\n", branch1, branch2);
1774
1775         index_fd = hold_locked_index(lock, 1);
1776
1777         for (i = 0; i < bases_count; i++) {
1778                 struct commit *ancestor = get_ref(bases[i]);
1779                 ca = commit_list_insert(ancestor, &ca);
1780         }
1781         clean = merge(h1, h2, branch1, branch2, ca, &result);
1782
1783         if (active_cache_changed &&
1784             (write_cache(index_fd, active_cache, active_nr) ||
1785              close(index_fd) || commit_locked_index(lock)))
1786                         die ("unable to write %s", get_index_file());
1787
1788         return clean ? 0: 1;
1789 }