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