git.oblomov.eu Git - git/blob - merge-recursive.c

   1 /*
   2  * Recursive Merge algorithm stolen from git-merge-recursive.py by
   3  * Fredrik Kuivinen.
   4  * The thieves were Alex Riesen and Johannes Schindelin, in June/July 2006
   5  */
   6 #include "cache.h"
   7 #include "cache-tree.h"
   8 #include "commit.h"
   9 #include "blob.h"
  10 #include "tree-walk.h"
  11 #include "diff.h"
  12 #include "diffcore.h"
  13 #include "run-command.h"
  14 #include "tag.h"
  15 #include "unpack-trees.h"
  16 #include "path-list.h"
  17 #include "xdiff-interface.h"
  18 #include "interpolate.h"
  19 #include "attr.h"
  20
  21 static int subtree_merge;
  22
  23 static struct tree *shift_tree_object(struct tree *one, struct tree *two)
  24 {
  25         unsigned char shifted[20];
  26
  27         /*
  28          * NEEDSWORK: this limits the recursion depth to hardcoded
  29          * value '2' to avoid excessive overhead.
  30          */
  31         shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
  32         if (!hashcmp(two->object.sha1, shifted))
  33                 return two;
  34         return lookup_tree(shifted);
  35 }
  36
  37 /*
  38  * A virtual commit has
  39  * - (const char *)commit->util set to the name, and
  40  * - *(int *)commit->object.sha1 set to the virtual id.
  41  */
  42
  43 static unsigned commit_list_count(const struct commit_list *l)
  44 {
  45         unsigned c = 0;
  46         for (; l; l = l->next )
  47                 c++;
  48         return c;
  49 }
  50
  51 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  52 {
  53         struct commit *commit = xcalloc(1, sizeof(struct commit));
  54         static unsigned virtual_id = 1;
  55         commit->tree = tree;
  56         commit->util = (void*)comment;
  57         *(int*)commit->object.sha1 = virtual_id++;
  58         /* avoid warnings */
  59         commit->object.parsed = 1;
  60         return commit;
  61 }
  62
  63 /*
  64  * Since we use get_tree_entry(), which does not put the read object into
  65  * the object pool, we cannot rely on a == b.
  66  */
  67 static int sha_eq(const unsigned char *a, const unsigned char *b)
  68 {
  69         if (!a && !b)
  70                 return 2;
  71         return a && b && hashcmp(a, b) == 0;
  72 }
  73
  74 /*
  75  * Since we want to write the index eventually, we cannot reuse the index
  76  * for these (temporary) data.
  77  */
  78 struct stage_data
  79 {
  80         struct
  81         {
  82                 unsigned mode;
  83                 unsigned char sha[20];
  84         } stages[4];
  85         unsigned processed:1;
  86 };
  87
  88 struct output_buffer
  89 {
  90         struct output_buffer *next;
  91         char *str;
  92 };
  93
  94 static struct path_list current_file_set = {NULL, 0, 0, 1};
  95 static struct path_list current_directory_set = {NULL, 0, 0, 1};
  96
  97 static int call_depth = 0;
  98 static int verbosity = 2;
  99 static int buffer_output = 1;
 100 static struct output_buffer *output_list, *output_end;
 101
 102 static int show (int v)
 103 {
 104         return (!call_depth && verbosity >= v) || verbosity >= 5;
 105 }
 106
 107 static void output(int v, const char *fmt, ...)
 108 {
 109         va_list args;
 110         va_start(args, fmt);
 111         if (buffer_output && show(v)) {
 112                 struct output_buffer *b = xmalloc(sizeof(*b));
 113                 nfvasprintf(&b->str, fmt, args);
 114                 b->next = NULL;
 115                 if (output_end)
 116                         output_end->next = b;
 117                 else
 118                         output_list = b;
 119                 output_end = b;
 120         } else if (show(v)) {
 121                 int i;
 122                 for (i = call_depth; i--;)
 123                         fputs("  ", stdout);
 124                 vfprintf(stdout, fmt, args);
 125                 fputc('\n', stdout);
 126         }
 127         va_end(args);
 128 }
 129
 130 static void flush_output()
 131 {
 132         struct output_buffer *b, *n;
 133         for (b = output_list; b; b = n) {
 134                 int i;
 135                 for (i = call_depth; i--;)
 136                         fputs("  ", stdout);
 137                 fputs(b->str, stdout);
 138                 fputc('\n', stdout);
 139                 n = b->next;
 140                 free(b->str);
 141                 free(b);
 142         }
 143         output_list = NULL;
 144         output_end = NULL;
 145 }
 146
 147 static void output_commit_title(struct commit *commit)
 148 {
 149         int i;
 150         flush_output();
 151         for (i = call_depth; i--;)
 152                 fputs("  ", stdout);
 153         if (commit->util)
 154                 printf("virtual %s\n", (char *)commit->util);
 155         else {
 156                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 157                 if (parse_commit(commit) != 0)
 158                         printf("(bad commit)\n");
 159                 else {
 160                         const char *s;
 161                         int len;
 162                         for (s = commit->buffer; *s; s++)
 163                                 if (*s == '\n' && s[1] == '\n') {
 164                                         s += 2;
 165                                         break;
 166                                 }
 167                         for (len = 0; s[len] && '\n' != s[len]; len++)
 168                                 ; /* do nothing */
 169                         printf("%.*s\n", len, s);
 170                 }
 171         }
 172 }
 173
 174 static struct cache_entry *make_cache_entry(unsigned int mode,
 175                 const unsigned char *sha1, const char *path, int stage, int refresh)
 176 {
 177         int size, len;
 178         struct cache_entry *ce;
 179
 180         if (!verify_path(path))
 181                 return NULL;
 182
 183         len = strlen(path);
 184         size = cache_entry_size(len);
 185         ce = xcalloc(1, size);
 186
 187         hashcpy(ce->sha1, sha1);
 188         memcpy(ce->name, path, len);
 189         ce->ce_flags = create_ce_flags(len, stage);
 190         ce->ce_mode = create_ce_mode(mode);
 191
 192         if (refresh)
 193                 return refresh_cache_entry(ce, 0);
 194
 195         return ce;
 196 }
 197
 198 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 199                 const char *path, int stage, int refresh, int options)
 200 {
 201         struct cache_entry *ce;
 202         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 203         if (!ce)
 204                 return error("addinfo_cache failed for path '%s'", path);
 205         return add_cache_entry(ce, options);
 206 }
 207
 208 /*
 209  * This is a global variable which is used in a number of places but
 210  * only written to in the 'merge' function.
 211  *
 212  * index_only == 1    => Don't leave any non-stage 0 entries in the cache and
 213  *                       don't update the working directory.
 214  *               0    => Leave unmerged entries in the cache and update
 215  *                       the working directory.
 216  */
 217 static int index_only = 0;
 218
 219 static int git_merge_trees(int index_only,
 220                            struct tree *common,
 221                            struct tree *head,
 222                            struct tree *merge)
 223 {
 224         int rc;
 225         struct object_list *trees = NULL;
 226         struct unpack_trees_options opts;
 227
 228         memset(&opts, 0, sizeof(opts));
 229         if (index_only)
 230                 opts.index_only = 1;
 231         else
 232                 opts.update = 1;
 233         opts.merge = 1;
 234         opts.head_idx = 2;
 235         opts.fn = threeway_merge;
 236
 237         object_list_append(&common->object, &trees);
 238         object_list_append(&head->object, &trees);
 239         object_list_append(&merge->object, &trees);
 240
 241         rc = unpack_trees(trees, &opts);
 242         cache_tree_free(&active_cache_tree);
 243         return rc;
 244 }
 245
 246 static int unmerged_index(void)
 247 {
 248         int i;
 249         for (i = 0; i < active_nr; i++) {
 250                 struct cache_entry *ce = active_cache[i];
 251                 if (ce_stage(ce))
 252                         return 1;
 253         }
 254         return 0;
 255 }
 256
 257 static struct tree *git_write_tree(void)
 258 {
 259         struct tree *result = NULL;
 260
 261         if (unmerged_index()) {
 262                 int i;
 263                 output(0, "There are unmerged index entries:");
 264                 for (i = 0; i < active_nr; i++) {
 265                         struct cache_entry *ce = active_cache[i];
 266                         if (ce_stage(ce))
 267                                 output(0, "%d %.*s", ce_stage(ce), ce_namelen(ce), ce->name);
 268                 }
 269                 return NULL;
 270         }
 271
 272         if (!active_cache_tree)
 273                 active_cache_tree = cache_tree();
 274
 275         if (!cache_tree_fully_valid(active_cache_tree) &&
 276             cache_tree_update(active_cache_tree,
 277                               active_cache, active_nr, 0, 0) < 0)
 278                 die("error building trees");
 279
 280         result = lookup_tree(active_cache_tree->sha1);
 281
 282         return result;
 283 }
 284
 285 static int save_files_dirs(const unsigned char *sha1,
 286                 const char *base, int baselen, const char *path,
 287                 unsigned int mode, int stage)
 288 {
 289         int len = strlen(path);
 290         char *newpath = xmalloc(baselen + len + 1);
 291         memcpy(newpath, base, baselen);
 292         memcpy(newpath + baselen, path, len);
 293         newpath[baselen + len] = '\0';
 294
 295         if (S_ISDIR(mode))
 296                 path_list_insert(newpath, &current_directory_set);
 297         else
 298                 path_list_insert(newpath, &current_file_set);
 299         free(newpath);
 300
 301         return READ_TREE_RECURSIVE;
 302 }
 303
 304 static int get_files_dirs(struct tree *tree)
 305 {
 306         int n;
 307         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs) != 0)
 308                 return 0;
 309         n = current_file_set.nr + current_directory_set.nr;
 310         return n;
 311 }
 312
 313 /*
 314  * Returns a index_entry instance which doesn't have to correspond to
 315  * a real cache entry in Git's index.
 316  */
 317 static struct stage_data *insert_stage_data(const char *path,
 318                 struct tree *o, struct tree *a, struct tree *b,
 319                 struct path_list *entries)
 320 {
 321         struct path_list_item *item;
 322         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 323         get_tree_entry(o->object.sha1, path,
 324                         e->stages[1].sha, &e->stages[1].mode);
 325         get_tree_entry(a->object.sha1, path,
 326                         e->stages[2].sha, &e->stages[2].mode);
 327         get_tree_entry(b->object.sha1, path,
 328                         e->stages[3].sha, &e->stages[3].mode);
 329         item = path_list_insert(path, entries);
 330         item->util = e;
 331         return e;
 332 }
 333
 334 /*
 335  * Create a dictionary mapping file names to stage_data objects. The
 336  * dictionary contains one entry for every path with a non-zero stage entry.
 337  */
 338 static struct path_list *get_unmerged(void)
 339 {
 340         struct path_list *unmerged = xcalloc(1, sizeof(struct path_list));
 341         int i;
 342
 343         unmerged->strdup_paths = 1;
 344
 345         for (i = 0; i < active_nr; i++) {
 346                 struct path_list_item *item;
 347                 struct stage_data *e;
 348                 struct cache_entry *ce = active_cache[i];
 349                 if (!ce_stage(ce))
 350                         continue;
 351
 352                 item = path_list_lookup(ce->name, unmerged);
 353                 if (!item) {
 354                         item = path_list_insert(ce->name, unmerged);
 355                         item->util = xcalloc(1, sizeof(struct stage_data));
 356                 }
 357                 e = item->util;
 358                 e->stages[ce_stage(ce)].mode = ntohl(ce->ce_mode);
 359                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 360         }
 361
 362         return unmerged;
 363 }
 364
 365 struct rename
 366 {
 367         struct diff_filepair *pair;
 368         struct stage_data *src_entry;
 369         struct stage_data *dst_entry;
 370         unsigned processed:1;
 371 };
 372
 373 /*
 374  * Get information of all renames which occurred between 'o_tree' and
 375  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 376  * 'b_tree') to be able to associate the correct cache entries with
 377  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 378  */
 379 static struct path_list *get_renames(struct tree *tree,
 380                                         struct tree *o_tree,
 381                                         struct tree *a_tree,
 382                                         struct tree *b_tree,
 383                                         struct path_list *entries)
 384 {
 385         int i;
 386         struct path_list *renames;
 387         struct diff_options opts;
 388
 389         renames = xcalloc(1, sizeof(struct path_list));
 390         diff_setup(&opts);
 391         opts.recursive = 1;
 392         opts.detect_rename = DIFF_DETECT_RENAME;
 393         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 394         if (diff_setup_done(&opts) < 0)
 395                 die("diff setup failed");
 396         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 397         diffcore_std(&opts);
 398         for (i = 0; i < diff_queued_diff.nr; ++i) {
 399                 struct path_list_item *item;
 400                 struct rename *re;
 401                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 402                 if (pair->status != 'R') {
 403                         diff_free_filepair(pair);
 404                         continue;
 405                 }
 406                 re = xmalloc(sizeof(*re));
 407                 re->processed = 0;
 408                 re->pair = pair;
 409                 item = path_list_lookup(re->pair->one->path, entries);
 410                 if (!item)
 411                         re->src_entry = insert_stage_data(re->pair->one->path,
 412                                         o_tree, a_tree, b_tree, entries);
 413                 else
 414                         re->src_entry = item->util;
 415
 416                 item = path_list_lookup(re->pair->two->path, entries);
 417                 if (!item)
 418                         re->dst_entry = insert_stage_data(re->pair->two->path,
 419                                         o_tree, a_tree, b_tree, entries);
 420                 else
 421                         re->dst_entry = item->util;
 422                 item = path_list_insert(pair->one->path, renames);
 423                 item->util = re;
 424         }
 425         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 426         diff_queued_diff.nr = 0;
 427         diff_flush(&opts);
 428         return renames;
 429 }
 430
 431 static int update_stages(const char *path, struct diff_filespec *o,
 432                          struct diff_filespec *a, struct diff_filespec *b,
 433                          int clear)
 434 {
 435         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 436         if (clear)
 437                 if (remove_file_from_cache(path))
 438                         return -1;
 439         if (o)
 440                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 441                         return -1;
 442         if (a)
 443                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 444                         return -1;
 445         if (b)
 446                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 447                         return -1;
 448         return 0;
 449 }
 450
 451 static int remove_path(const char *name)
 452 {
 453         int ret, len;
 454         char *slash, *dirs;
 455
 456         ret = unlink(name);
 457         if (ret)
 458                 return ret;
 459         len = strlen(name);
 460         dirs = xmalloc(len+1);
 461         memcpy(dirs, name, len);
 462         dirs[len] = '\0';
 463         while ((slash = strrchr(name, '/'))) {
 464                 *slash = '\0';
 465                 len = slash - name;
 466                 if (rmdir(name) != 0)
 467                         break;
 468         }
 469         free(dirs);
 470         return ret;
 471 }
 472
 473 static int remove_file(int clean, const char *path, int no_wd)
 474 {
 475         int update_cache = index_only || clean;
 476         int update_working_directory = !index_only && !no_wd;
 477
 478         if (update_cache) {
 479                 if (remove_file_from_cache(path))
 480                         return -1;
 481         }
 482         if (update_working_directory) {
 483                 unlink(path);
 484                 if (errno != ENOENT || errno != EISDIR)
 485                         return -1;
 486                 remove_path(path);
 487         }
 488         return 0;
 489 }
 490
 491 static char *unique_path(const char *path, const char *branch)
 492 {
 493         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 494         int suffix = 0;
 495         struct stat st;
 496         char *p = newpath + strlen(path);
 497         strcpy(newpath, path);
 498         *(p++) = '~';
 499         strcpy(p, branch);
 500         for (; *p; ++p)
 501                 if ('/' == *p)
 502                         *p = '_';
 503         while (path_list_has_path(&current_file_set, newpath) ||
 504                path_list_has_path(&current_directory_set, newpath) ||
 505                lstat(newpath, &st) == 0)
 506                 sprintf(p, "_%d", suffix++);
 507
 508         path_list_insert(newpath, &current_file_set);
 509         return newpath;
 510 }
 511
 512 static int mkdir_p(const char *path, unsigned long mode)
 513 {
 514         /* path points to cache entries, so xstrdup before messing with it */
 515         char *buf = xstrdup(path);
 516         int result = safe_create_leading_directories(buf);
 517         free(buf);
 518         return result;
 519 }
 520
 521 static void flush_buffer(int fd, const char *buf, unsigned long size)
 522 {
 523         while (size > 0) {
 524                 long ret = write_in_full(fd, buf, size);
 525                 if (ret < 0) {
 526                         /* Ignore epipe */
 527                         if (errno == EPIPE)
 528                                 break;
 529                         die("merge-recursive: %s", strerror(errno));
 530                 } else if (!ret) {
 531                         die("merge-recursive: disk full?");
 532                 }
 533                 size -= ret;
 534                 buf += ret;
 535         }
 536 }
 537
 538 static int make_room_for_path(const char *path)
 539 {
 540         int status;
 541         const char *msg = "failed to create path '%s'%s";
 542
 543         status = mkdir_p(path, 0777);
 544         if (status) {
 545                 if (status == -3) {
 546                         /* something else exists */
 547                         error(msg, path, ": perhaps a D/F conflict?");
 548                         return -1;
 549                 }
 550                 die(msg, path, "");
 551         }
 552
 553         /* Successful unlink is good.. */
 554         if (!unlink(path))
 555                 return 0;
 556         /* .. and so is no existing file */
 557         if (errno == ENOENT)
 558                 return 0;
 559         /* .. but not some other error (who really cares what?) */
 560         return error(msg, path, ": perhaps a D/F conflict?");
 561 }
 562
 563 static void update_file_flags(const unsigned char *sha,
 564                               unsigned mode,
 565                               const char *path,
 566                               int update_cache,
 567                               int update_wd)
 568 {
 569         if (index_only)
 570                 update_wd = 0;
 571
 572         if (update_wd) {
 573                 enum object_type type;
 574                 void *buf;
 575                 unsigned long size;
 576
 577                 buf = read_sha1_file(sha, &type, &size);
 578                 if (!buf)
 579                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 580                 if (type != OBJ_BLOB)
 581                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 582
 583                 if (make_room_for_path(path) < 0) {
 584                         update_wd = 0;
 585                         goto update_index;
 586                 }
 587                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 588                         int fd;
 589                         if (mode & 0100)
 590                                 mode = 0777;
 591                         else
 592                                 mode = 0666;
 593                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 594                         if (fd < 0)
 595                                 die("failed to open %s: %s", path, strerror(errno));
 596                         flush_buffer(fd, buf, size);
 597                         close(fd);
 598                 } else if (S_ISLNK(mode)) {
 599                         char *lnk = xmalloc(size + 1);
 600                         memcpy(lnk, buf, size);
 601                         lnk[size] = '\0';
 602                         mkdir_p(path, 0777);
 603                         unlink(path);
 604                         symlink(lnk, path);
 605                         free(lnk);
 606                 } else
 607                         die("do not know what to do with %06o %s '%s'",
 608                             mode, sha1_to_hex(sha), path);
 609         }
 610  update_index:
 611         if (update_cache)
 612                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 613 }
 614
 615 static void update_file(int clean,
 616                         const unsigned char *sha,
 617                         unsigned mode,
 618                         const char *path)
 619 {
 620         update_file_flags(sha, mode, path, index_only || clean, !index_only);
 621 }
 622
 623 /* Low level file merging, update and removal */
 624
 625 struct merge_file_info
 626 {
 627         unsigned char sha[20];
 628         unsigned mode;
 629         unsigned clean:1,
 630                  merge:1;
 631 };
 632
 633 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 634 {
 635         unsigned long size;
 636         enum object_type type;
 637
 638         if (!hashcmp(sha1, null_sha1)) {
 639                 mm->ptr = xstrdup("");
 640                 mm->size = 0;
 641                 return;
 642         }
 643
 644         mm->ptr = read_sha1_file(sha1, &type, &size);
 645         if (!mm->ptr || type != OBJ_BLOB)
 646                 die("unable to read blob object %s", sha1_to_hex(sha1));
 647         mm->size = size;
 648 }
 649
 650 /*
 651  * Customizable low-level merge drivers support.
 652  */
 653
 654 struct ll_merge_driver;
 655 typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
 656                            const char *path,
 657                            mmfile_t *orig,
 658                            mmfile_t *src1, const char *name1,
 659                            mmfile_t *src2, const char *name2,
 660                            mmbuffer_t *result);
 661
 662 struct ll_merge_driver {
 663         const char *name;
 664         const char *description;
 665         ll_merge_fn fn;
 666         const char *recursive;
 667         struct ll_merge_driver *next;
 668         char *cmdline;
 669 };
 670
 671 /*
 672  * Built-in low-levels
 673  */
 674 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 675                         const char *path_unused,
 676                         mmfile_t *orig,
 677                         mmfile_t *src1, const char *name1,
 678                         mmfile_t *src2, const char *name2,
 679                         mmbuffer_t *result)
 680 {
 681         xpparam_t xpp;
 682
 683         if (buffer_is_binary(orig->ptr, orig->size) ||
 684                         buffer_is_binary(src1->ptr, src1->size) ||
 685                         buffer_is_binary(src2->ptr, src2->size))
 686                 return error("Cannot merge binary files: %s vs. %s\n",
 687                         name1, name2);
 688
 689         memset(&xpp, 0, sizeof(xpp));
 690         return xdl_merge(orig,
 691                          src1, name1,
 692                          src2, name2,
 693                          &xpp, XDL_MERGE_ZEALOUS,
 694                          result);
 695 }
 696
 697 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 698                           const char *path_unused,
 699                           mmfile_t *orig,
 700                           mmfile_t *src1, const char *name1,
 701                           mmfile_t *src2, const char *name2,
 702                           mmbuffer_t *result)
 703 {
 704         char *src, *dst;
 705         long size;
 706         const int marker_size = 7;
 707
 708         int status = ll_xdl_merge(drv_unused, path_unused,
 709                                   orig, src1, NULL, src2, NULL, result);
 710         if (status <= 0)
 711                 return status;
 712         size = result->size;
 713         src = dst = result->ptr;
 714         while (size) {
 715                 char ch;
 716                 if ((marker_size < size) &&
 717                     (*src == '<' || *src == '=' || *src == '>')) {
 718                         int i;
 719                         ch = *src;
 720                         for (i = 0; i < marker_size; i++)
 721                                 if (src[i] != ch)
 722                                         goto not_a_marker;
 723                         if (src[marker_size] != '\n')
 724                                 goto not_a_marker;
 725                         src += marker_size + 1;
 726                         size -= marker_size + 1;
 727                         continue;
 728                 }
 729         not_a_marker:
 730                 do {
 731                         ch = *src++;
 732                         *dst++ = ch;
 733                         size--;
 734                 } while (ch != '\n' && size);
 735         }
 736         result->size = dst - result->ptr;
 737         return 0;
 738 }
 739
 740 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 741                            const char *path_unused,
 742                            mmfile_t *orig,
 743                            mmfile_t *src1, const char *name1,
 744                            mmfile_t *src2, const char *name2,
 745                            mmbuffer_t *result)
 746 {
 747         /*
 748          * The tentative merge result is "ours" for the final round,
 749          * or common ancestor for an internal merge.  Still return
 750          * "conflicted merge" status.
 751          */
 752         mmfile_t *stolen = index_only ? orig : src1;
 753
 754         result->ptr = stolen->ptr;
 755         result->size = stolen->size;
 756         stolen->ptr = NULL;
 757         return 1;
 758 }
 759
 760 #define LL_BINARY_MERGE 0
 761 #define LL_TEXT_MERGE 1
 762 #define LL_UNION_MERGE 2
 763 static struct ll_merge_driver ll_merge_drv[] = {
 764         { "binary", "built-in binary merge", ll_binary_merge },
 765         { "text", "built-in 3-way text merge", ll_xdl_merge },
 766         { "union", "built-in union merge", ll_union_merge },
 767 };
 768
 769 static void create_temp(mmfile_t *src, char *path)
 770 {
 771         int fd;
 772
 773         strcpy(path, ".merge_file_XXXXXX");
 774         fd = mkstemp(path);
 775         if (fd < 0)
 776                 die("unable to create temp-file");
 777         if (write_in_full(fd, src->ptr, src->size) != src->size)
 778                 die("unable to write temp-file");
 779         close(fd);
 780 }
 781
 782 /*
 783  * User defined low-level merge driver support.
 784  */
 785 static int ll_ext_merge(const struct ll_merge_driver *fn,
 786                         const char *path,
 787                         mmfile_t *orig,
 788                         mmfile_t *src1, const char *name1,
 789                         mmfile_t *src2, const char *name2,
 790                         mmbuffer_t *result)
 791 {
 792         char temp[3][50];
 793         char cmdbuf[2048];
 794         struct interp table[] = {
 795                 { "%O" },
 796                 { "%A" },
 797                 { "%B" },
 798         };
 799         struct child_process child;
 800         const char *args[20];
 801         int status, fd, i;
 802         struct stat st;
 803
 804         if (fn->cmdline == NULL)
 805                 die("custom merge driver %s lacks command line.", fn->name);
 806
 807         result->ptr = NULL;
 808         result->size = 0;
 809         create_temp(orig, temp[0]);
 810         create_temp(src1, temp[1]);
 811         create_temp(src2, temp[2]);
 812
 813         interp_set_entry(table, 0, temp[0]);
 814         interp_set_entry(table, 1, temp[1]);
 815         interp_set_entry(table, 2, temp[2]);
 816
 817         output(1, "merging %s using %s", path,
 818                fn->description ? fn->description : fn->name);
 819
 820         interpolate(cmdbuf, sizeof(cmdbuf), fn->cmdline, table, 3);
 821
 822         memset(&child, 0, sizeof(child));
 823         child.argv = args;
 824         args[0] = "sh";
 825         args[1] = "-c";
 826         args[2] = cmdbuf;
 827         args[3] = NULL;
 828
 829         status = run_command(&child);
 830         if (status < -ERR_RUN_COMMAND_FORK)
 831                 ; /* failure in run-command */
 832         else
 833                 status = -status;
 834         fd = open(temp[1], O_RDONLY);
 835         if (fd < 0)
 836                 goto bad;
 837         if (fstat(fd, &st))
 838                 goto close_bad;
 839         result->size = st.st_size;
 840         result->ptr = xmalloc(result->size + 1);
 841         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 842                 free(result->ptr);
 843                 result->ptr = NULL;
 844                 result->size = 0;
 845         }
 846  close_bad:
 847         close(fd);
 848  bad:
 849         for (i = 0; i < 3; i++)
 850                 unlink(temp[i]);
 851         return status;
 852 }
 853
 854 /*
 855  * merge.default and merge.driver configuration items
 856  */
 857 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 858 static const char *default_ll_merge;
 859
 860 static int read_merge_config(const char *var, const char *value)
 861 {
 862         struct ll_merge_driver *fn;
 863         const char *ep, *name;
 864         int namelen;
 865
 866         if (!strcmp(var, "merge.default")) {
 867                 if (value)
 868                         default_ll_merge = strdup(value);
 869                 return 0;
 870         }
 871
 872         /*
 873          * We are not interested in anything but "merge.<name>.variable";
 874          * especially, we do not want to look at variables such as
 875          * "merge.summary", "merge.tool", and "merge.verbosity".
 876          */
 877         if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
 878                 return 0;
 879
 880         /*
 881          * Find existing one as we might be processing merge.<name>.var2
 882          * after seeing merge.<name>.var1.
 883          */
 884         name = var + 6;
 885         namelen = ep - name;
 886         for (fn = ll_user_merge; fn; fn = fn->next)
 887                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 888                         break;
 889         if (!fn) {
 890                 char *namebuf;
 891                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
 892                 namebuf = xmalloc(namelen + 1);
 893                 memcpy(namebuf, name, namelen);
 894                 namebuf[namelen] = 0;
 895                 fn->name = namebuf;
 896                 fn->fn = ll_ext_merge;
 897                 fn->next = NULL;
 898                 *ll_user_merge_tail = fn;
 899                 ll_user_merge_tail = &(fn->next);
 900         }
 901
 902         ep++;
 903
 904         if (!strcmp("name", ep)) {
 905                 if (!value)
 906                         return error("%s: lacks value", var);
 907                 fn->description = strdup(value);
 908                 return 0;
 909         }
 910
 911         if (!strcmp("driver", ep)) {
 912                 if (!value)
 913                         return error("%s: lacks value", var);
 914                 /*
 915                  * merge.<name>.driver specifies the command line:
 916                  *
 917                  *      command-line
 918                  *
 919                  * The command-line will be interpolated with the following
 920                  * tokens and is given to the shell:
 921                  *
 922                  *    %O - temporary file name for the merge base.
 923                  *    %A - temporary file name for our version.
 924                  *    %B - temporary file name for the other branches' version.
 925                  *
 926                  * The external merge driver should write the results in the
 927                  * file named by %A, and signal that it has done with zero exit
 928                  * status.
 929                  */
 930                 fn->cmdline = strdup(value);
 931                 return 0;
 932         }
 933
 934         if (!strcmp("recursive", ep)) {
 935                 if (!value)
 936                         return error("%s: lacks value", var);
 937                 fn->recursive = strdup(value);
 938                 return 0;
 939         }
 940
 941         return 0;
 942 }
 943
 944 static void initialize_ll_merge(void)
 945 {
 946         if (ll_user_merge_tail)
 947                 return;
 948         ll_user_merge_tail = &ll_user_merge;
 949         git_config(read_merge_config);
 950 }
 951
 952 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 953 {
 954         struct ll_merge_driver *fn;
 955         const char *name;
 956         int i;
 957
 958         initialize_ll_merge();
 959
 960         if (ATTR_TRUE(merge_attr))
 961                 return &ll_merge_drv[LL_TEXT_MERGE];
 962         else if (ATTR_FALSE(merge_attr))
 963                 return &ll_merge_drv[LL_BINARY_MERGE];
 964         else if (ATTR_UNSET(merge_attr)) {
 965                 if (!default_ll_merge)
 966                         return &ll_merge_drv[LL_TEXT_MERGE];
 967                 else
 968                         name = default_ll_merge;
 969         }
 970         else
 971                 name = merge_attr;
 972
 973         for (fn = ll_user_merge; fn; fn = fn->next)
 974                 if (!strcmp(fn->name, name))
 975                         return fn;
 976
 977         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 978                 if (!strcmp(ll_merge_drv[i].name, name))
 979                         return &ll_merge_drv[i];
 980
 981         /* default to the 3-way */
 982         return &ll_merge_drv[LL_TEXT_MERGE];
 983 }
 984
 985 static const char *git_path_check_merge(const char *path)
 986 {
 987         static struct git_attr_check attr_merge_check;
 988
 989         if (!attr_merge_check.attr)
 990                 attr_merge_check.attr = git_attr("merge", 5);
 991
 992         if (git_checkattr(path, 1, &attr_merge_check))
 993                 return NULL;
 994         return attr_merge_check.value;
 995 }
 996
 997 static int ll_merge(mmbuffer_t *result_buf,
 998                     struct diff_filespec *o,
 999                     struct diff_filespec *a,
1000                     struct diff_filespec *b,
1001                     const char *branch1,
1002                     const char *branch2)
1003 {
1004         mmfile_t orig, src1, src2;
1005         char *name1, *name2;
1006         int merge_status;
1007         const char *ll_driver_name;
1008         const struct ll_merge_driver *driver;
1009
1010         name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
1011         name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
1012
1013         fill_mm(o->sha1, &orig);
1014         fill_mm(a->sha1, &src1);
1015         fill_mm(b->sha1, &src2);
1016
1017         ll_driver_name = git_path_check_merge(a->path);
1018         driver = find_ll_merge_driver(ll_driver_name);
1019
1020         if (index_only && driver->recursive)
1021                 driver = find_ll_merge_driver(driver->recursive);
1022         merge_status = driver->fn(driver, a->path,
1023                                   &orig, &src1, name1, &src2, name2,
1024                                   result_buf);
1025
1026         free(name1);
1027         free(name2);
1028         free(orig.ptr);
1029         free(src1.ptr);
1030         free(src2.ptr);
1031         return merge_status;
1032 }
1033
1034 static struct merge_file_info merge_file(struct diff_filespec *o,
1035                 struct diff_filespec *a, struct diff_filespec *b,
1036                 const char *branch1, const char *branch2)
1037 {
1038         struct merge_file_info result;
1039         result.merge = 0;
1040         result.clean = 1;
1041
1042         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
1043                 result.clean = 0;
1044                 if (S_ISREG(a->mode)) {
1045                         result.mode = a->mode;
1046                         hashcpy(result.sha, a->sha1);
1047                 } else {
1048                         result.mode = b->mode;
1049                         hashcpy(result.sha, b->sha1);
1050                 }
1051         } else {
1052                 if (!sha_eq(a->sha1, o->sha1) && !sha_eq(b->sha1, o->sha1))
1053                         result.merge = 1;
1054
1055                 result.mode = a->mode == o->mode ? b->mode: a->mode;
1056
1057                 if (sha_eq(a->sha1, o->sha1))
1058                         hashcpy(result.sha, b->sha1);
1059                 else if (sha_eq(b->sha1, o->sha1))
1060                         hashcpy(result.sha, a->sha1);
1061                 else if (S_ISREG(a->mode)) {
1062                         mmbuffer_t result_buf;
1063                         int merge_status;
1064
1065                         merge_status = ll_merge(&result_buf, o, a, b,
1066                                                 branch1, branch2);
1067
1068                         if ((merge_status < 0) || !result_buf.ptr)
1069                                 die("Failed to execute internal merge");
1070
1071                         if (write_sha1_file(result_buf.ptr, result_buf.size,
1072                                             blob_type, result.sha))
1073                                 die("Unable to add %s to database",
1074                                     a->path);
1075
1076                         free(result_buf.ptr);
1077                         result.clean = (merge_status == 0);
1078                 } else {
1079                         if (!(S_ISLNK(a->mode) || S_ISLNK(b->mode)))
1080                                 die("cannot merge modes?");
1081
1082                         hashcpy(result.sha, a->sha1);
1083
1084                         if (!sha_eq(a->sha1, b->sha1))
1085                                 result.clean = 0;
1086                 }
1087         }
1088
1089         return result;
1090 }
1091
1092 static void conflict_rename_rename(struct rename *ren1,
1093                                    const char *branch1,
1094                                    struct rename *ren2,
1095                                    const char *branch2)
1096 {
1097         char *del[2];
1098         int delp = 0;
1099         const char *ren1_dst = ren1->pair->two->path;
1100         const char *ren2_dst = ren2->pair->two->path;
1101         const char *dst_name1 = ren1_dst;
1102         const char *dst_name2 = ren2_dst;
1103         if (path_list_has_path(&current_directory_set, ren1_dst)) {
1104                 dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
1105                 output(1, "%s is a directory in %s added as %s instead",
1106                        ren1_dst, branch2, dst_name1);
1107                 remove_file(0, ren1_dst, 0);
1108         }
1109         if (path_list_has_path(&current_directory_set, ren2_dst)) {
1110                 dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
1111                 output(1, "%s is a directory in %s added as %s instead",
1112                        ren2_dst, branch1, dst_name2);
1113                 remove_file(0, ren2_dst, 0);
1114         }
1115         if (index_only) {
1116                 remove_file_from_cache(dst_name1);
1117                 remove_file_from_cache(dst_name2);
1118                 /*
1119                  * Uncomment to leave the conflicting names in the resulting tree
1120                  *
1121                  * update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
1122                  * update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
1123                  */
1124         } else {
1125                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
1126                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
1127         }
1128         while (delp--)
1129                 free(del[delp]);
1130 }
1131
1132 static void conflict_rename_dir(struct rename *ren1,
1133                                 const char *branch1)
1134 {
1135         char *new_path = unique_path(ren1->pair->two->path, branch1);
1136         output(1, "Renamed %s to %s instead", ren1->pair->one->path, new_path);
1137         remove_file(0, ren1->pair->two->path, 0);
1138         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
1139         free(new_path);
1140 }
1141
1142 static void conflict_rename_rename_2(struct rename *ren1,
1143                                      const char *branch1,
1144                                      struct rename *ren2,
1145                                      const char *branch2)
1146 {
1147         char *new_path1 = unique_path(ren1->pair->two->path, branch1);
1148         char *new_path2 = unique_path(ren2->pair->two->path, branch2);
1149         output(1, "Renamed %s to %s and %s to %s instead",
1150                ren1->pair->one->path, new_path1,
1151                ren2->pair->one->path, new_path2);
1152         remove_file(0, ren1->pair->two->path, 0);
1153         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
1154         update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
1155         free(new_path2);
1156         free(new_path1);
1157 }
1158
1159 static int process_renames(struct path_list *a_renames,
1160                            struct path_list *b_renames,
1161                            const char *a_branch,
1162                            const char *b_branch)
1163 {
1164         int clean_merge = 1, i, j;
1165         struct path_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
1166         const struct rename *sre;
1167
1168         for (i = 0; i < a_renames->nr; i++) {
1169                 sre = a_renames->items[i].util;
1170                 path_list_insert(sre->pair->two->path, &a_by_dst)->util
1171                         = sre->dst_entry;
1172         }
1173         for (i = 0; i < b_renames->nr; i++) {
1174                 sre = b_renames->items[i].util;
1175                 path_list_insert(sre->pair->two->path, &b_by_dst)->util
1176                         = sre->dst_entry;
1177         }
1178
1179         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
1180                 int compare;
1181                 char *src;
1182                 struct path_list *renames1, *renames2, *renames2Dst;
1183                 struct rename *ren1 = NULL, *ren2 = NULL;
1184                 const char *branch1, *branch2;
1185                 const char *ren1_src, *ren1_dst;
1186
1187                 if (i >= a_renames->nr) {
1188                         compare = 1;
1189                         ren2 = b_renames->items[j++].util;
1190                 } else if (j >= b_renames->nr) {
1191                         compare = -1;
1192                         ren1 = a_renames->items[i++].util;
1193                 } else {
1194                         compare = strcmp(a_renames->items[i].path,
1195                                         b_renames->items[j].path);
1196                         if (compare <= 0)
1197                                 ren1 = a_renames->items[i++].util;
1198                         if (compare >= 0)
1199                                 ren2 = b_renames->items[j++].util;
1200                 }
1201
1202                 /* TODO: refactor, so that 1/2 are not needed */
1203                 if (ren1) {
1204                         renames1 = a_renames;
1205                         renames2 = b_renames;
1206                         renames2Dst = &b_by_dst;
1207                         branch1 = a_branch;
1208                         branch2 = b_branch;
1209                 } else {
1210                         struct rename *tmp;
1211                         renames1 = b_renames;
1212                         renames2 = a_renames;
1213                         renames2Dst = &a_by_dst;
1214                         branch1 = b_branch;
1215                         branch2 = a_branch;
1216                         tmp = ren2;
1217                         ren2 = ren1;
1218                         ren1 = tmp;
1219                 }
1220                 src = ren1->pair->one->path;
1221
1222                 ren1->dst_entry->processed = 1;
1223                 ren1->src_entry->processed = 1;
1224
1225                 if (ren1->processed)
1226                         continue;
1227                 ren1->processed = 1;
1228
1229                 ren1_src = ren1->pair->one->path;
1230                 ren1_dst = ren1->pair->two->path;
1231
1232                 if (ren2) {
1233                         const char *ren2_src = ren2->pair->one->path;
1234                         const char *ren2_dst = ren2->pair->two->path;
1235                         /* Renamed in 1 and renamed in 2 */
1236                         if (strcmp(ren1_src, ren2_src) != 0)
1237                                 die("ren1.src != ren2.src");
1238                         ren2->dst_entry->processed = 1;
1239                         ren2->processed = 1;
1240                         if (strcmp(ren1_dst, ren2_dst) != 0) {
1241                                 clean_merge = 0;
1242                                 output(1, "CONFLICT (rename/rename): "
1243                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
1244                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
1245                                        src, ren1_dst, branch1,
1246                                        src, ren2_dst, branch2,
1247                                        index_only ? " (left unresolved)": "");
1248                                 if (index_only) {
1249                                         remove_file_from_cache(src);
1250                                         update_file(0, ren1->pair->one->sha1,
1251                                                     ren1->pair->one->mode, src);
1252                                 }
1253                                 conflict_rename_rename(ren1, branch1, ren2, branch2);
1254                         } else {
1255                                 struct merge_file_info mfi;
1256                                 remove_file(1, ren1_src, 1);
1257                                 mfi = merge_file(ren1->pair->one,
1258                                                  ren1->pair->two,
1259                                                  ren2->pair->two,
1260                                                  branch1,
1261                                                  branch2);
1262                                 if (mfi.merge || !mfi.clean)
1263                                         output(1, "Renamed %s->%s", src, ren1_dst);
1264
1265                                 if (mfi.merge)
1266                                         output(2, "Auto-merged %s", ren1_dst);
1267
1268                                 if (!mfi.clean) {
1269                                         output(1, "CONFLICT (content): merge conflict in %s",
1270                                                ren1_dst);
1271                                         clean_merge = 0;
1272
1273                                         if (!index_only)
1274                                                 update_stages(ren1_dst,
1275                                                               ren1->pair->one,
1276                                                               ren1->pair->two,
1277                                                               ren2->pair->two,
1278                                                               1 /* clear */);
1279                                 }
1280                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1281                         }
1282                 } else {
1283                         /* Renamed in 1, maybe changed in 2 */
1284                         struct path_list_item *item;
1285                         /* we only use sha1 and mode of these */
1286                         struct diff_filespec src_other, dst_other;
1287                         int try_merge, stage = a_renames == renames1 ? 3: 2;
1288
1289                         remove_file(1, ren1_src, index_only || stage == 3);
1290
1291                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
1292                         src_other.mode = ren1->src_entry->stages[stage].mode;
1293                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
1294                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
1295
1296                         try_merge = 0;
1297
1298                         if (path_list_has_path(&current_directory_set, ren1_dst)) {
1299                                 clean_merge = 0;
1300                                 output(1, "CONFLICT (rename/directory): Renamed %s->%s in %s "
1301                                        " directory %s added in %s",
1302                                        ren1_src, ren1_dst, branch1,
1303                                        ren1_dst, branch2);
1304                                 conflict_rename_dir(ren1, branch1);
1305                         } else if (sha_eq(src_other.sha1, null_sha1)) {
1306                                 clean_merge = 0;
1307                                 output(1, "CONFLICT (rename/delete): Renamed %s->%s in %s "
1308                                        "and deleted in %s",
1309                                        ren1_src, ren1_dst, branch1,
1310                                        branch2);
1311                                 update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
1312                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
1313                                 const char *new_path;
1314                                 clean_merge = 0;
1315                                 try_merge = 1;
1316                                 output(1, "CONFLICT (rename/add): Renamed %s->%s in %s. "
1317                                        "%s added in %s",
1318                                        ren1_src, ren1_dst, branch1,
1319                                        ren1_dst, branch2);
1320                                 new_path = unique_path(ren1_dst, branch2);
1321                                 output(1, "Added as %s instead", new_path);
1322                                 update_file(0, dst_other.sha1, dst_other.mode, new_path);
1323                         } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
1324                                 ren2 = item->util;
1325                                 clean_merge = 0;
1326                                 ren2->processed = 1;
1327                                 output(1, "CONFLICT (rename/rename): Renamed %s->%s in %s. "
1328                                        "Renamed %s->%s in %s",
1329                                        ren1_src, ren1_dst, branch1,
1330                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
1331                                 conflict_rename_rename_2(ren1, branch1, ren2, branch2);
1332                         } else
1333                                 try_merge = 1;
1334
1335                         if (try_merge) {
1336                                 struct diff_filespec *o, *a, *b;
1337                                 struct merge_file_info mfi;
1338                                 src_other.path = (char *)ren1_src;
1339
1340                                 o = ren1->pair->one;
1341                                 if (a_renames == renames1) {
1342                                         a = ren1->pair->two;
1343                                         b = &src_other;
1344                                 } else {
1345                                         b = ren1->pair->two;
1346                                         a = &src_other;
1347                                 }
1348                                 mfi = merge_file(o, a, b,
1349                                                 a_branch, b_branch);
1350
1351                                 if (mfi.clean &&
1352                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
1353                                     mfi.mode == ren1->pair->two->mode)
1354                                         /*
1355                                          * This messaged is part of
1356                                          * t6022 test. If you change
1357                                          * it update the test too.
1358                                          */
1359                                         output(3, "Skipped %s (merged same as existing)", ren1_dst);
1360                                 else {
1361                                         if (mfi.merge || !mfi.clean)
1362                                                 output(1, "Renamed %s => %s", ren1_src, ren1_dst);
1363                                         if (mfi.merge)
1364                                                 output(2, "Auto-merged %s", ren1_dst);
1365                                         if (!mfi.clean) {
1366                                                 output(1, "CONFLICT (rename/modify): Merge conflict in %s",
1367                                                        ren1_dst);
1368                                                 clean_merge = 0;
1369
1370                                                 if (!index_only)
1371                                                         update_stages(ren1_dst,
1372                                                                       o, a, b, 1);
1373                                         }
1374                                         update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1375                                 }
1376                         }
1377                 }
1378         }
1379         path_list_clear(&a_by_dst, 0);
1380         path_list_clear(&b_by_dst, 0);
1381
1382         return clean_merge;
1383 }
1384
1385 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1386 {
1387         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1388 }
1389
1390 /* Per entry merge function */
1391 static int process_entry(const char *path, struct stage_data *entry,
1392                          const char *branch1,
1393                          const char *branch2)
1394 {
1395         /*
1396         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1397         print_index_entry("\tpath: ", entry);
1398         */
1399         int clean_merge = 1;
1400         unsigned o_mode = entry->stages[1].mode;
1401         unsigned a_mode = entry->stages[2].mode;
1402         unsigned b_mode = entry->stages[3].mode;
1403         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1404         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1405         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1406
1407         if (o_sha && (!a_sha || !b_sha)) {
1408                 /* Case A: Deleted in one */
1409                 if ((!a_sha && !b_sha) ||
1410                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1411                     (!a_sha && sha_eq(b_sha, o_sha))) {
1412                         /* Deleted in both or deleted in one and
1413                          * unchanged in the other */
1414                         if (a_sha)
1415                                 output(2, "Removed %s", path);
1416                         /* do not touch working file if it did not exist */
1417                         remove_file(1, path, !a_sha);
1418                 } else {
1419                         /* Deleted in one and changed in the other */
1420                         clean_merge = 0;
1421                         if (!a_sha) {
1422                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1423                                        "and modified in %s. Version %s of %s left in tree.",
1424                                        path, branch1,
1425                                        branch2, branch2, path);
1426                                 update_file(0, b_sha, b_mode, path);
1427                         } else {
1428                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1429                                        "and modified in %s. Version %s of %s left in tree.",
1430                                        path, branch2,
1431                                        branch1, branch1, path);
1432                                 update_file(0, a_sha, a_mode, path);
1433                         }
1434                 }
1435
1436         } else if ((!o_sha && a_sha && !b_sha) ||
1437                    (!o_sha && !a_sha && b_sha)) {
1438                 /* Case B: Added in one. */
1439                 const char *add_branch;
1440                 const char *other_branch;
1441                 unsigned mode;
1442                 const unsigned char *sha;
1443                 const char *conf;
1444
1445                 if (a_sha) {
1446                         add_branch = branch1;
1447                         other_branch = branch2;
1448                         mode = a_mode;
1449                         sha = a_sha;
1450                         conf = "file/directory";
1451                 } else {
1452                         add_branch = branch2;
1453                         other_branch = branch1;
1454                         mode = b_mode;
1455                         sha = b_sha;
1456                         conf = "directory/file";
1457                 }
1458                 if (path_list_has_path(&current_directory_set, path)) {
1459                         const char *new_path = unique_path(path, add_branch);
1460                         clean_merge = 0;
1461                         output(1, "CONFLICT (%s): There is a directory with name %s in %s. "
1462                                "Added %s as %s",
1463                                conf, path, other_branch, path, new_path);
1464                         remove_file(0, path, 0);
1465                         update_file(0, sha, mode, new_path);
1466                 } else {
1467                         output(2, "Added %s", path);
1468                         update_file(1, sha, mode, path);
1469                 }
1470         } else if (a_sha && b_sha) {
1471                 /* Case C: Added in both (check for same permissions) and */
1472                 /* case D: Modified in both, but differently. */
1473                 const char *reason = "content";
1474                 struct merge_file_info mfi;
1475                 struct diff_filespec o, a, b;
1476
1477                 if (!o_sha) {
1478                         reason = "add/add";
1479                         o_sha = (unsigned char *)null_sha1;
1480                 }
1481                 output(2, "Auto-merged %s", path);
1482                 o.path = a.path = b.path = (char *)path;
1483                 hashcpy(o.sha1, o_sha);
1484                 o.mode = o_mode;
1485                 hashcpy(a.sha1, a_sha);
1486                 a.mode = a_mode;
1487                 hashcpy(b.sha1, b_sha);
1488                 b.mode = b_mode;
1489
1490                 mfi = merge_file(&o, &a, &b,
1491                                  branch1, branch2);
1492
1493                 if (mfi.clean)
1494                         update_file(1, mfi.sha, mfi.mode, path);
1495                 else {
1496                         clean_merge = 0;
1497                         output(1, "CONFLICT (%s): Merge conflict in %s",
1498                                         reason, path);
1499
1500                         if (index_only)
1501                                 update_file(0, mfi.sha, mfi.mode, path);
1502                         else
1503                                 update_file_flags(mfi.sha, mfi.mode, path,
1504                                               0 /* update_cache */, 1 /* update_working_directory */);
1505                 }
1506         } else if (!o_sha && !a_sha && !b_sha) {
1507                 /*
1508                  * this entry was deleted altogether. a_mode == 0 means
1509                  * we had that path and want to actively remove it.
1510                  */
1511                 remove_file(1, path, !a_mode);
1512         } else
1513                 die("Fatal merge failure, shouldn't happen.");
1514
1515         return clean_merge;
1516 }
1517
1518 static int merge_trees(struct tree *head,
1519                        struct tree *merge,
1520                        struct tree *common,
1521                        const char *branch1,
1522                        const char *branch2,
1523                        struct tree **result)
1524 {
1525         int code, clean;
1526
1527         if (subtree_merge) {
1528                 merge = shift_tree_object(head, merge);
1529                 common = shift_tree_object(head, common);
1530         }
1531
1532         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1533                 output(0, "Already uptodate!");
1534                 *result = head;
1535                 return 1;
1536         }
1537
1538         code = git_merge_trees(index_only, common, head, merge);
1539
1540         if (code != 0)
1541                 die("merging of trees %s and %s failed",
1542                     sha1_to_hex(head->object.sha1),
1543                     sha1_to_hex(merge->object.sha1));
1544
1545         if (unmerged_index()) {
1546                 struct path_list *entries, *re_head, *re_merge;
1547                 int i;
1548                 path_list_clear(&current_file_set, 1);
1549                 path_list_clear(&current_directory_set, 1);
1550                 get_files_dirs(head);
1551                 get_files_dirs(merge);
1552
1553                 entries = get_unmerged();
1554                 re_head  = get_renames(head, common, head, merge, entries);
1555                 re_merge = get_renames(merge, common, head, merge, entries);
1556                 clean = process_renames(re_head, re_merge,
1557                                 branch1, branch2);
1558                 for (i = 0; i < entries->nr; i++) {
1559                         const char *path = entries->items[i].path;
1560                         struct stage_data *e = entries->items[i].util;
1561                         if (!e->processed
1562                                 && !process_entry(path, e, branch1, branch2))
1563                                 clean = 0;
1564                 }
1565
1566                 path_list_clear(re_merge, 0);
1567                 path_list_clear(re_head, 0);
1568                 path_list_clear(entries, 1);
1569
1570         }
1571         else
1572                 clean = 1;
1573
1574         if (index_only)
1575                 *result = git_write_tree();
1576
1577         return clean;
1578 }
1579
1580 static struct commit_list *reverse_commit_list(struct commit_list *list)
1581 {
1582         struct commit_list *next = NULL, *current, *backup;
1583         for (current = list; current; current = backup) {
1584                 backup = current->next;
1585                 current->next = next;
1586                 next = current;
1587         }
1588         return next;
1589 }
1590
1591 /*
1592  * Merge the commits h1 and h2, return the resulting virtual
1593  * commit object and a flag indicating the cleanness of the merge.
1594  */
1595 static int merge(struct commit *h1,
1596                  struct commit *h2,
1597                  const char *branch1,
1598                  const char *branch2,
1599                  struct commit_list *ca,
1600                  struct commit **result)
1601 {
1602         struct commit_list *iter;
1603         struct commit *merged_common_ancestors;
1604         struct tree *mrtree;
1605         int clean;
1606
1607         if (show(4)) {
1608                 output(4, "Merging:");
1609                 output_commit_title(h1);
1610                 output_commit_title(h2);
1611         }
1612
1613         if (!ca) {
1614                 ca = get_merge_bases(h1, h2, 1);
1615                 ca = reverse_commit_list(ca);
1616         }
1617
1618         if (show(5)) {
1619                 output(5, "found %u common ancestor(s):", commit_list_count(ca));
1620                 for (iter = ca; iter; iter = iter->next)
1621                         output_commit_title(iter->item);
1622         }
1623
1624         merged_common_ancestors = pop_commit(&ca);
1625         if (merged_common_ancestors == NULL) {
1626                 /* if there is no common ancestor, make an empty tree */
1627                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1628
1629                 tree->object.parsed = 1;
1630                 tree->object.type = OBJ_TREE;
1631                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1632                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1633         }
1634
1635         for (iter = ca; iter; iter = iter->next) {
1636                 call_depth++;
1637                 /*
1638                  * When the merge fails, the result contains files
1639                  * with conflict markers. The cleanness flag is
1640                  * ignored, it was never actually used, as result of
1641                  * merge_trees has always overwritten it: the committed
1642                  * "conflicts" were already resolved.
1643                  */
1644                 discard_cache();
1645                 merge(merged_common_ancestors, iter->item,
1646                       "Temporary merge branch 1",
1647                       "Temporary merge branch 2",
1648                       NULL,
1649                       &merged_common_ancestors);
1650                 call_depth--;
1651
1652                 if (!merged_common_ancestors)
1653                         die("merge returned no commit");
1654         }
1655
1656         discard_cache();
1657         if (!call_depth) {
1658                 read_cache();
1659                 index_only = 0;
1660         } else
1661                 index_only = 1;
1662
1663         clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
1664                             branch1, branch2, &mrtree);
1665
1666         if (index_only) {
1667                 *result = make_virtual_commit(mrtree, "merged tree");
1668                 commit_list_insert(h1, &(*result)->parents);
1669                 commit_list_insert(h2, &(*result)->parents->next);
1670         }
1671         flush_output();
1672         return clean;
1673 }
1674
1675 static const char *better_branch_name(const char *branch)
1676 {
1677         static char githead_env[8 + 40 + 1];
1678         char *name;
1679
1680         if (strlen(branch) != 40)
1681                 return branch;
1682         sprintf(githead_env, "GITHEAD_%s", branch);
1683         name = getenv(githead_env);
1684         return name ? name : branch;
1685 }
1686
1687 static struct commit *get_ref(const char *ref)
1688 {
1689         unsigned char sha1[20];
1690         struct object *object;
1691
1692         if (get_sha1(ref, sha1))
1693                 die("Could not resolve ref '%s'", ref);
1694         object = deref_tag(parse_object(sha1), ref, strlen(ref));
1695         if (object->type == OBJ_TREE)
1696                 return make_virtual_commit((struct tree*)object,
1697                         better_branch_name(ref));
1698         if (object->type != OBJ_COMMIT)
1699                 return NULL;
1700         if (parse_commit((struct commit *)object))
1701                 die("Could not parse commit '%s'", sha1_to_hex(object->sha1));
1702         return (struct commit *)object;
1703 }
1704
1705 static int merge_config(const char *var, const char *value)
1706 {
1707         if (!strcasecmp(var, "merge.verbosity")) {
1708                 verbosity = git_config_int(var, value);
1709                 return 0;
1710         }
1711         return git_default_config(var, value);
1712 }
1713
1714 int main(int argc, char *argv[])
1715 {
1716         static const char *bases[20];
1717         static unsigned bases_count = 0;
1718         int i, clean;
1719         const char *branch1, *branch2;
1720         struct commit *result, *h1, *h2;
1721         struct commit_list *ca = NULL;
1722         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1723         int index_fd;
1724
1725         if (argv[0]) {
1726                 int namelen = strlen(argv[0]);
1727                 if (8 < namelen &&
1728                     !strcmp(argv[0] + namelen - 8, "-subtree"))
1729                         subtree_merge = 1;
1730         }
1731
1732         git_config(merge_config);
1733         if (getenv("GIT_MERGE_VERBOSITY"))
1734                 verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1735
1736         if (argc < 4)
1737                 die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
1738
1739         for (i = 1; i < argc; ++i) {
1740                 if (!strcmp(argv[i], "--"))
1741                         break;
1742                 if (bases_count < sizeof(bases)/sizeof(*bases))
1743                         bases[bases_count++] = argv[i];
1744         }
1745         if (argc - i != 3) /* "--" "<head>" "<remote>" */
1746                 die("Not handling anything other than two heads merge.");
1747         if (verbosity >= 5)
1748                 buffer_output = 0;
1749
1750         branch1 = argv[++i];
1751         branch2 = argv[++i];
1752
1753         h1 = get_ref(branch1);
1754         h2 = get_ref(branch2);
1755
1756         branch1 = better_branch_name(branch1);
1757         branch2 = better_branch_name(branch2);
1758
1759         if (show(3))
1760                 printf("Merging %s with %s\n", branch1, branch2);
1761
1762         index_fd = hold_locked_index(lock, 1);
1763
1764         for (i = 0; i < bases_count; i++) {
1765                 struct commit *ancestor = get_ref(bases[i]);
1766                 ca = commit_list_insert(ancestor, &ca);
1767         }
1768         clean = merge(h1, h2, branch1, branch2, ca, &result);
1769
1770         if (active_cache_changed &&
1771             (write_cache(index_fd, active_cache, active_nr) ||
1772              close(index_fd) || commit_locked_index(lock)))
1773                         die ("unable to write %s", get_index_file());
1774
1775         return clean ? 0: 1;
1776 }