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