merge-recursive.c

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