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

   1 /*
   2  * Recursive Merge algorithm stolen from git-merge-recursive.py by
   3  * Fredrik Kuivinen.
   4  * The thieves were Alex Riesen and Johannes Schindelin, in June/July 2006
   5  */
   6 #include "advice.h"
   7 #include "cache.h"
   8 #include "cache-tree.h"
   9 #include "commit.h"
  10 #include "blob.h"
  11 #include "builtin.h"
  12 #include "tree-walk.h"
  13 #include "diff.h"
  14 #include "diffcore.h"
  15 #include "tag.h"
  16 #include "unpack-trees.h"
  17 #include "string-list.h"
  18 #include "xdiff-interface.h"
  19 #include "ll-merge.h"
  20 #include "attr.h"
  21 #include "merge-recursive.h"
  22 #include "dir.h"
  23
  24 static struct tree *shift_tree_object(struct tree *one, struct tree *two,
  25                                       const char *subtree_shift)
  26 {
  27         unsigned char shifted[20];
  28
  29         if (!*subtree_shift) {
  30                 shift_tree(one->object.sha1, two->object.sha1, shifted, 0);
  31         } else {
  32                 shift_tree_by(one->object.sha1, two->object.sha1, shifted,
  33                               subtree_shift);
  34         }
  35         if (!hashcmp(two->object.sha1, shifted))
  36                 return two;
  37         return lookup_tree(shifted);
  38 }
  39
  40 /*
  41  * A virtual commit has (const char *)commit->util set to the name.
  42  */
  43
  44 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  45 {
  46         struct commit *commit = xcalloc(1, sizeof(struct commit));
  47         commit->tree = tree;
  48         commit->util = (void*)comment;
  49         /* avoid warnings */
  50         commit->object.parsed = 1;
  51         return commit;
  52 }
  53
  54 /*
  55  * Since we use get_tree_entry(), which does not put the read object into
  56  * the object pool, we cannot rely on a == b.
  57  */
  58 static int sha_eq(const unsigned char *a, const unsigned char *b)
  59 {
  60         if (!a && !b)
  61                 return 2;
  62         return a && b && hashcmp(a, b) == 0;
  63 }
  64
  65 /*
  66  * Since we want to write the index eventually, we cannot reuse the index
  67  * for these (temporary) data.
  68  */
  69 struct stage_data
  70 {
  71         struct
  72         {
  73                 unsigned mode;
  74                 unsigned char sha[20];
  75         } stages[4];
  76         unsigned processed:1;
  77 };
  78
  79 static int show(struct merge_options *o, int v)
  80 {
  81         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
  82 }
  83
  84 static void flush_output(struct merge_options *o)
  85 {
  86         if (o->obuf.len) {
  87                 fputs(o->obuf.buf, stdout);
  88                 strbuf_reset(&o->obuf);
  89         }
  90 }
  91
  92 __attribute__((format (printf, 3, 4)))
  93 static void output(struct merge_options *o, int v, const char *fmt, ...)
  94 {
  95         int len;
  96         va_list ap;
  97
  98         if (!show(o, v))
  99                 return;
 100
 101         strbuf_grow(&o->obuf, o->call_depth * 2 + 2);
 102         memset(o->obuf.buf + o->obuf.len, ' ', o->call_depth * 2);
 103         strbuf_setlen(&o->obuf, o->obuf.len + o->call_depth * 2);
 104
 105         va_start(ap, fmt);
 106         len = vsnprintf(o->obuf.buf + o->obuf.len, strbuf_avail(&o->obuf), fmt, ap);
 107         va_end(ap);
 108
 109         if (len < 0)
 110                 len = 0;
 111         if (len >= strbuf_avail(&o->obuf)) {
 112                 strbuf_grow(&o->obuf, len + 2);
 113                 va_start(ap, fmt);
 114                 len = vsnprintf(o->obuf.buf + o->obuf.len, strbuf_avail(&o->obuf), fmt, ap);
 115                 va_end(ap);
 116                 if (len >= strbuf_avail(&o->obuf)) {
 117                         die("this should not happen, your snprintf is broken");
 118                 }
 119         }
 120         strbuf_setlen(&o->obuf, o->obuf.len + len);
 121         strbuf_add(&o->obuf, "\n", 1);
 122         if (!o->buffer_output)
 123                 flush_output(o);
 124 }
 125
 126 static void output_commit_title(struct merge_options *o, struct commit *commit)
 127 {
 128         int i;
 129         flush_output(o);
 130         for (i = o->call_depth; i--;)
 131                 fputs("  ", stdout);
 132         if (commit->util)
 133                 printf("virtual %s\n", (char *)commit->util);
 134         else {
 135                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 136                 if (parse_commit(commit) != 0)
 137                         printf("(bad commit)\n");
 138                 else {
 139                         const char *title;
 140                         int len = find_commit_subject(commit->buffer, &title);
 141                         if (len)
 142                                 printf("%.*s\n", len, title);
 143                 }
 144         }
 145 }
 146
 147 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 148                 const char *path, int stage, int refresh, int options)
 149 {
 150         struct cache_entry *ce;
 151         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 152         if (!ce)
 153                 return error("addinfo_cache failed for path '%s'", path);
 154         return add_cache_entry(ce, options);
 155 }
 156
 157 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 158 {
 159         parse_tree(tree);
 160         init_tree_desc(desc, tree->buffer, tree->size);
 161 }
 162
 163 static int git_merge_trees(int index_only,
 164                            struct tree *common,
 165                            struct tree *head,
 166                            struct tree *merge)
 167 {
 168         int rc;
 169         struct tree_desc t[3];
 170         struct unpack_trees_options opts;
 171
 172         memset(&opts, 0, sizeof(opts));
 173         if (index_only)
 174                 opts.index_only = 1;
 175         else
 176                 opts.update = 1;
 177         opts.merge = 1;
 178         opts.head_idx = 2;
 179         opts.fn = threeway_merge;
 180         opts.src_index = &the_index;
 181         opts.dst_index = &the_index;
 182         opts.msgs = get_porcelain_error_msgs();
 183
 184         init_tree_desc_from_tree(t+0, common);
 185         init_tree_desc_from_tree(t+1, head);
 186         init_tree_desc_from_tree(t+2, merge);
 187
 188         rc = unpack_trees(3, t, &opts);
 189         cache_tree_free(&active_cache_tree);
 190         return rc;
 191 }
 192
 193 struct tree *write_tree_from_memory(struct merge_options *o)
 194 {
 195         struct tree *result = NULL;
 196
 197         if (unmerged_cache()) {
 198                 int i;
 199                 fprintf(stderr, "BUG: There are unmerged index entries:\n");
 200                 for (i = 0; i < active_nr; i++) {
 201                         struct cache_entry *ce = active_cache[i];
 202                         if (ce_stage(ce))
 203                                 fprintf(stderr, "BUG: %d %.*s", ce_stage(ce),
 204                                         (int)ce_namelen(ce), ce->name);
 205                 }
 206                 die("Bug in merge-recursive.c");
 207         }
 208
 209         if (!active_cache_tree)
 210                 active_cache_tree = cache_tree();
 211
 212         if (!cache_tree_fully_valid(active_cache_tree) &&
 213             cache_tree_update(active_cache_tree,
 214                               active_cache, active_nr, 0, 0) < 0)
 215                 die("error building trees");
 216
 217         result = lookup_tree(active_cache_tree->sha1);
 218
 219         return result;
 220 }
 221
 222 static int save_files_dirs(const unsigned char *sha1,
 223                 const char *base, int baselen, const char *path,
 224                 unsigned int mode, int stage, void *context)
 225 {
 226         int len = strlen(path);
 227         char *newpath = xmalloc(baselen + len + 1);
 228         struct merge_options *o = context;
 229
 230         memcpy(newpath, base, baselen);
 231         memcpy(newpath + baselen, path, len);
 232         newpath[baselen + len] = '\0';
 233
 234         if (S_ISDIR(mode))
 235                 string_list_insert(&o->current_directory_set, newpath);
 236         else
 237                 string_list_insert(&o->current_file_set, newpath);
 238         free(newpath);
 239
 240         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
 241 }
 242
 243 static int get_files_dirs(struct merge_options *o, struct tree *tree)
 244 {
 245         int n;
 246         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs, o))
 247                 return 0;
 248         n = o->current_file_set.nr + o->current_directory_set.nr;
 249         return n;
 250 }
 251
 252 /*
 253  * Returns an index_entry instance which doesn't have to correspond to
 254  * a real cache entry in Git's index.
 255  */
 256 static struct stage_data *insert_stage_data(const char *path,
 257                 struct tree *o, struct tree *a, struct tree *b,
 258                 struct string_list *entries)
 259 {
 260         struct string_list_item *item;
 261         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 262         get_tree_entry(o->object.sha1, path,
 263                         e->stages[1].sha, &e->stages[1].mode);
 264         get_tree_entry(a->object.sha1, path,
 265                         e->stages[2].sha, &e->stages[2].mode);
 266         get_tree_entry(b->object.sha1, path,
 267                         e->stages[3].sha, &e->stages[3].mode);
 268         item = string_list_insert(entries, path);
 269         item->util = e;
 270         return e;
 271 }
 272
 273 /*
 274  * Create a dictionary mapping file names to stage_data objects. The
 275  * dictionary contains one entry for every path with a non-zero stage entry.
 276  */
 277 static struct string_list *get_unmerged(void)
 278 {
 279         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
 280         int i;
 281
 282         unmerged->strdup_strings = 1;
 283
 284         for (i = 0; i < active_nr; i++) {
 285                 struct string_list_item *item;
 286                 struct stage_data *e;
 287                 struct cache_entry *ce = active_cache[i];
 288                 if (!ce_stage(ce))
 289                         continue;
 290
 291                 item = string_list_lookup(unmerged, ce->name);
 292                 if (!item) {
 293                         item = string_list_insert(unmerged, ce->name);
 294                         item->util = xcalloc(1, sizeof(struct stage_data));
 295                 }
 296                 e = item->util;
 297                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
 298                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 299         }
 300
 301         return unmerged;
 302 }
 303
 304 struct rename
 305 {
 306         struct diff_filepair *pair;
 307         struct stage_data *src_entry;
 308         struct stage_data *dst_entry;
 309         unsigned processed:1;
 310 };
 311
 312 /*
 313  * Get information of all renames which occurred between 'o_tree' and
 314  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 315  * 'b_tree') to be able to associate the correct cache entries with
 316  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 317  */
 318 static struct string_list *get_renames(struct merge_options *o,
 319                                        struct tree *tree,
 320                                        struct tree *o_tree,
 321                                        struct tree *a_tree,
 322                                        struct tree *b_tree,
 323                                        struct string_list *entries)
 324 {
 325         int i;
 326         struct string_list *renames;
 327         struct diff_options opts;
 328
 329         renames = xcalloc(1, sizeof(struct string_list));
 330         diff_setup(&opts);
 331         DIFF_OPT_SET(&opts, RECURSIVE);
 332         opts.detect_rename = DIFF_DETECT_RENAME;
 333         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 334                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 335                             500;
 336         opts.warn_on_too_large_rename = 1;
 337         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 338         if (diff_setup_done(&opts) < 0)
 339                 die("diff setup failed");
 340         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 341         diffcore_std(&opts);
 342         for (i = 0; i < diff_queued_diff.nr; ++i) {
 343                 struct string_list_item *item;
 344                 struct rename *re;
 345                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 346                 if (pair->status != 'R') {
 347                         diff_free_filepair(pair);
 348                         continue;
 349                 }
 350                 re = xmalloc(sizeof(*re));
 351                 re->processed = 0;
 352                 re->pair = pair;
 353                 item = string_list_lookup(entries, re->pair->one->path);
 354                 if (!item)
 355                         re->src_entry = insert_stage_data(re->pair->one->path,
 356                                         o_tree, a_tree, b_tree, entries);
 357                 else
 358                         re->src_entry = item->util;
 359
 360                 item = string_list_lookup(entries, re->pair->two->path);
 361                 if (!item)
 362                         re->dst_entry = insert_stage_data(re->pair->two->path,
 363                                         o_tree, a_tree, b_tree, entries);
 364                 else
 365                         re->dst_entry = item->util;
 366                 item = string_list_insert(renames, pair->one->path);
 367                 item->util = re;
 368         }
 369         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 370         diff_queued_diff.nr = 0;
 371         diff_flush(&opts);
 372         return renames;
 373 }
 374
 375 static int update_stages(const char *path, struct diff_filespec *o,
 376                          struct diff_filespec *a, struct diff_filespec *b,
 377                          int clear)
 378 {
 379         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 380         if (clear)
 381                 if (remove_file_from_cache(path))
 382                         return -1;
 383         if (o)
 384                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 385                         return -1;
 386         if (a)
 387                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 388                         return -1;
 389         if (b)
 390                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 391                         return -1;
 392         return 0;
 393 }
 394
 395 static int remove_file(struct merge_options *o, int clean,
 396                        const char *path, int no_wd)
 397 {
 398         int update_cache = o->call_depth || clean;
 399         int update_working_directory = !o->call_depth && !no_wd;
 400
 401         if (update_cache) {
 402                 if (remove_file_from_cache(path))
 403                         return -1;
 404         }
 405         if (update_working_directory) {
 406                 if (remove_path(path))
 407                         return -1;
 408         }
 409         return 0;
 410 }
 411
 412 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
 413 {
 414         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 415         int suffix = 0;
 416         struct stat st;
 417         char *p = newpath + strlen(path);
 418         strcpy(newpath, path);
 419         *(p++) = '~';
 420         strcpy(p, branch);
 421         for (; *p; ++p)
 422                 if ('/' == *p)
 423                         *p = '_';
 424         while (string_list_has_string(&o->current_file_set, newpath) ||
 425                string_list_has_string(&o->current_directory_set, newpath) ||
 426                lstat(newpath, &st) == 0)
 427                 sprintf(p, "_%d", suffix++);
 428
 429         string_list_insert(&o->current_file_set, newpath);
 430         return newpath;
 431 }
 432
 433 static void flush_buffer(int fd, const char *buf, unsigned long size)
 434 {
 435         while (size > 0) {
 436                 long ret = write_in_full(fd, buf, size);
 437                 if (ret < 0) {
 438                         /* Ignore epipe */
 439                         if (errno == EPIPE)
 440                                 break;
 441                         die_errno("merge-recursive");
 442                 } else if (!ret) {
 443                         die("merge-recursive: disk full?");
 444                 }
 445                 size -= ret;
 446                 buf += ret;
 447         }
 448 }
 449
 450 static int would_lose_untracked(const char *path)
 451 {
 452         int pos = cache_name_pos(path, strlen(path));
 453
 454         if (pos < 0)
 455                 pos = -1 - pos;
 456         while (pos < active_nr &&
 457                !strcmp(path, active_cache[pos]->name)) {
 458                 /*
 459                  * If stage #0, it is definitely tracked.
 460                  * If it has stage #2 then it was tracked
 461                  * before this merge started.  All other
 462                  * cases the path was not tracked.
 463                  */
 464                 switch (ce_stage(active_cache[pos])) {
 465                 case 0:
 466                 case 2:
 467                         return 0;
 468                 }
 469                 pos++;
 470         }
 471         return file_exists(path);
 472 }
 473
 474 static int make_room_for_path(const char *path)
 475 {
 476         int status;
 477         const char *msg = "failed to create path '%s'%s";
 478
 479         status = safe_create_leading_directories_const(path);
 480         if (status) {
 481                 if (status == -3) {
 482                         /* something else exists */
 483                         error(msg, path, ": perhaps a D/F conflict?");
 484                         return -1;
 485                 }
 486                 die(msg, path, "");
 487         }
 488
 489         /*
 490          * Do not unlink a file in the work tree if we are not
 491          * tracking it.
 492          */
 493         if (would_lose_untracked(path))
 494                 return error("refusing to lose untracked file at '%s'",
 495                              path);
 496
 497         /* Successful unlink is good.. */
 498         if (!unlink(path))
 499                 return 0;
 500         /* .. and so is no existing file */
 501         if (errno == ENOENT)
 502                 return 0;
 503         /* .. but not some other error (who really cares what?) */
 504         return error(msg, path, ": perhaps a D/F conflict?");
 505 }
 506
 507 static void update_file_flags(struct merge_options *o,
 508                               const unsigned char *sha,
 509                               unsigned mode,
 510                               const char *path,
 511                               int update_cache,
 512                               int update_wd)
 513 {
 514         if (o->call_depth)
 515                 update_wd = 0;
 516
 517         if (update_wd) {
 518                 enum object_type type;
 519                 void *buf;
 520                 unsigned long size;
 521
 522                 if (S_ISGITLINK(mode))
 523                         /*
 524                          * We may later decide to recursively descend into
 525                          * the submodule directory and update its index
 526                          * and/or work tree, but we do not do that now.
 527                          */
 528                         goto update_index;
 529
 530                 buf = read_sha1_file(sha, &type, &size);
 531                 if (!buf)
 532                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 533                 if (type != OBJ_BLOB)
 534                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 535                 if (S_ISREG(mode)) {
 536                         struct strbuf strbuf = STRBUF_INIT;
 537                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
 538                                 free(buf);
 539                                 size = strbuf.len;
 540                                 buf = strbuf_detach(&strbuf, NULL);
 541                         }
 542                 }
 543
 544                 if (make_room_for_path(path) < 0) {
 545                         update_wd = 0;
 546                         free(buf);
 547                         goto update_index;
 548                 }
 549                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 550                         int fd;
 551                         if (mode & 0100)
 552                                 mode = 0777;
 553                         else
 554                                 mode = 0666;
 555                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 556                         if (fd < 0)
 557                                 die_errno("failed to open '%s'", path);
 558                         flush_buffer(fd, buf, size);
 559                         close(fd);
 560                 } else if (S_ISLNK(mode)) {
 561                         char *lnk = xmemdupz(buf, size);
 562                         safe_create_leading_directories_const(path);
 563                         unlink(path);
 564                         if (symlink(lnk, path))
 565                                 die_errno("failed to symlink '%s'", path);
 566                         free(lnk);
 567                 } else
 568                         die("do not know what to do with %06o %s '%s'",
 569                             mode, sha1_to_hex(sha), path);
 570                 free(buf);
 571         }
 572  update_index:
 573         if (update_cache)
 574                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 575 }
 576
 577 static void update_file(struct merge_options *o,
 578                         int clean,
 579                         const unsigned char *sha,
 580                         unsigned mode,
 581                         const char *path)
 582 {
 583         update_file_flags(o, sha, mode, path, o->call_depth || clean, !o->call_depth);
 584 }
 585
 586 /* Low level file merging, update and removal */
 587
 588 struct merge_file_info
 589 {
 590         unsigned char sha[20];
 591         unsigned mode;
 592         unsigned clean:1,
 593                  merge:1;
 594 };
 595
 596 static int merge_3way(struct merge_options *o,
 597                       mmbuffer_t *result_buf,
 598                       struct diff_filespec *one,
 599                       struct diff_filespec *a,
 600                       struct diff_filespec *b,
 601                       const char *branch1,
 602                       const char *branch2)
 603 {
 604         mmfile_t orig, src1, src2;
 605         char *base_name, *name1, *name2;
 606         int merge_status;
 607         int favor;
 608
 609         if (o->call_depth)
 610                 favor = 0;
 611         else {
 612                 switch (o->recursive_variant) {
 613                 case MERGE_RECURSIVE_OURS:
 614                         favor = XDL_MERGE_FAVOR_OURS;
 615                         break;
 616                 case MERGE_RECURSIVE_THEIRS:
 617                         favor = XDL_MERGE_FAVOR_THEIRS;
 618                         break;
 619                 default:
 620                         favor = 0;
 621                         break;
 622                 }
 623         }
 624
 625         if (strcmp(a->path, b->path) ||
 626             (o->ancestor != NULL && strcmp(a->path, one->path) != 0)) {
 627                 base_name = o->ancestor == NULL ? NULL :
 628                         xstrdup(mkpath("%s:%s", o->ancestor, one->path));
 629                 name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 630                 name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 631         } else {
 632                 base_name = o->ancestor == NULL ? NULL :
 633                         xstrdup(mkpath("%s", o->ancestor));
 634                 name1 = xstrdup(mkpath("%s", branch1));
 635                 name2 = xstrdup(mkpath("%s", branch2));
 636         }
 637
 638         read_mmblob(&orig, one->sha1);
 639         read_mmblob(&src1, a->sha1);
 640         read_mmblob(&src2, b->sha1);
 641
 642         merge_status = ll_merge(result_buf, a->path, &orig, base_name,
 643                                 &src1, name1, &src2, name2,
 644                                 (!!o->call_depth) | (favor << 1));
 645
 646         free(name1);
 647         free(name2);
 648         free(orig.ptr);
 649         free(src1.ptr);
 650         free(src2.ptr);
 651         return merge_status;
 652 }
 653
 654 static struct merge_file_info merge_file(struct merge_options *o,
 655                                          struct diff_filespec *one,
 656                                          struct diff_filespec *a,
 657                                          struct diff_filespec *b,
 658                                          const char *branch1,
 659                                          const char *branch2)
 660 {
 661         struct merge_file_info result;
 662         result.merge = 0;
 663         result.clean = 1;
 664
 665         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 666                 result.clean = 0;
 667                 if (S_ISREG(a->mode)) {
 668                         result.mode = a->mode;
 669                         hashcpy(result.sha, a->sha1);
 670                 } else {
 671                         result.mode = b->mode;
 672                         hashcpy(result.sha, b->sha1);
 673                 }
 674         } else {
 675                 if (!sha_eq(a->sha1, one->sha1) && !sha_eq(b->sha1, one->sha1))
 676                         result.merge = 1;
 677
 678                 /*
 679                  * Merge modes
 680                  */
 681                 if (a->mode == b->mode || a->mode == one->mode)
 682                         result.mode = b->mode;
 683                 else {
 684                         result.mode = a->mode;
 685                         if (b->mode != one->mode) {
 686                                 result.clean = 0;
 687                                 result.merge = 1;
 688                         }
 689                 }
 690
 691                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, one->sha1))
 692                         hashcpy(result.sha, b->sha1);
 693                 else if (sha_eq(b->sha1, one->sha1))
 694                         hashcpy(result.sha, a->sha1);
 695                 else if (S_ISREG(a->mode)) {
 696                         mmbuffer_t result_buf;
 697                         int merge_status;
 698
 699                         merge_status = merge_3way(o, &result_buf, one, a, b,
 700                                                   branch1, branch2);
 701
 702                         if ((merge_status < 0) || !result_buf.ptr)
 703                                 die("Failed to execute internal merge");
 704
 705                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 706                                             blob_type, result.sha))
 707                                 die("Unable to add %s to database",
 708                                     a->path);
 709
 710                         free(result_buf.ptr);
 711                         result.clean = (merge_status == 0);
 712                 } else if (S_ISGITLINK(a->mode)) {
 713                         result.clean = 0;
 714                         hashcpy(result.sha, a->sha1);
 715                 } else if (S_ISLNK(a->mode)) {
 716                         hashcpy(result.sha, a->sha1);
 717
 718                         if (!sha_eq(a->sha1, b->sha1))
 719                                 result.clean = 0;
 720                 } else {
 721                         die("unsupported object type in the tree");
 722                 }
 723         }
 724
 725         return result;
 726 }
 727
 728 static void conflict_rename_rename(struct merge_options *o,
 729                                    struct rename *ren1,
 730                                    const char *branch1,
 731                                    struct rename *ren2,
 732                                    const char *branch2)
 733 {
 734         char *del[2];
 735         int delp = 0;
 736         const char *ren1_dst = ren1->pair->two->path;
 737         const char *ren2_dst = ren2->pair->two->path;
 738         const char *dst_name1 = ren1_dst;
 739         const char *dst_name2 = ren2_dst;
 740         if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
 741                 dst_name1 = del[delp++] = unique_path(o, ren1_dst, branch1);
 742                 output(o, 1, "%s is a directory in %s adding as %s instead",
 743                        ren1_dst, branch2, dst_name1);
 744                 remove_file(o, 0, ren1_dst, 0);
 745         }
 746         if (string_list_has_string(&o->current_directory_set, ren2_dst)) {
 747                 dst_name2 = del[delp++] = unique_path(o, ren2_dst, branch2);
 748                 output(o, 1, "%s is a directory in %s adding as %s instead",
 749                        ren2_dst, branch1, dst_name2);
 750                 remove_file(o, 0, ren2_dst, 0);
 751         }
 752         if (o->call_depth) {
 753                 remove_file_from_cache(dst_name1);
 754                 remove_file_from_cache(dst_name2);
 755                 /*
 756                  * Uncomment to leave the conflicting names in the resulting tree
 757                  *
 758                  * update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
 759                  * update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
 760                  */
 761         } else {
 762                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
 763                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
 764         }
 765         while (delp--)
 766                 free(del[delp]);
 767 }
 768
 769 static void conflict_rename_dir(struct merge_options *o,
 770                                 struct rename *ren1,
 771                                 const char *branch1)
 772 {
 773         char *new_path = unique_path(o, ren1->pair->two->path, branch1);
 774         output(o, 1, "Renaming %s to %s instead", ren1->pair->one->path, new_path);
 775         remove_file(o, 0, ren1->pair->two->path, 0);
 776         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
 777         free(new_path);
 778 }
 779
 780 static void conflict_rename_rename_2(struct merge_options *o,
 781                                      struct rename *ren1,
 782                                      const char *branch1,
 783                                      struct rename *ren2,
 784                                      const char *branch2)
 785 {
 786         char *new_path1 = unique_path(o, ren1->pair->two->path, branch1);
 787         char *new_path2 = unique_path(o, ren2->pair->two->path, branch2);
 788         output(o, 1, "Renaming %s to %s and %s to %s instead",
 789                ren1->pair->one->path, new_path1,
 790                ren2->pair->one->path, new_path2);
 791         remove_file(o, 0, ren1->pair->two->path, 0);
 792         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 793         update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 794         free(new_path2);
 795         free(new_path1);
 796 }
 797
 798 static int process_renames(struct merge_options *o,
 799                            struct string_list *a_renames,
 800                            struct string_list *b_renames)
 801 {
 802         int clean_merge = 1, i, j;
 803         struct string_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
 804         const struct rename *sre;
 805
 806         for (i = 0; i < a_renames->nr; i++) {
 807                 sre = a_renames->items[i].util;
 808                 string_list_insert(&a_by_dst, sre->pair->two->path)->util
 809                         = sre->dst_entry;
 810         }
 811         for (i = 0; i < b_renames->nr; i++) {
 812                 sre = b_renames->items[i].util;
 813                 string_list_insert(&b_by_dst, sre->pair->two->path)->util
 814                         = sre->dst_entry;
 815         }
 816
 817         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 818                 char *src;
 819                 struct string_list *renames1, *renames2Dst;
 820                 struct rename *ren1 = NULL, *ren2 = NULL;
 821                 const char *branch1, *branch2;
 822                 const char *ren1_src, *ren1_dst;
 823
 824                 if (i >= a_renames->nr) {
 825                         ren2 = b_renames->items[j++].util;
 826                 } else if (j >= b_renames->nr) {
 827                         ren1 = a_renames->items[i++].util;
 828                 } else {
 829                         int compare = strcmp(a_renames->items[i].string,
 830                                              b_renames->items[j].string);
 831                         if (compare <= 0)
 832                                 ren1 = a_renames->items[i++].util;
 833                         if (compare >= 0)
 834                                 ren2 = b_renames->items[j++].util;
 835                 }
 836
 837                 /* TODO: refactor, so that 1/2 are not needed */
 838                 if (ren1) {
 839                         renames1 = a_renames;
 840                         renames2Dst = &b_by_dst;
 841                         branch1 = o->branch1;
 842                         branch2 = o->branch2;
 843                 } else {
 844                         struct rename *tmp;
 845                         renames1 = b_renames;
 846                         renames2Dst = &a_by_dst;
 847                         branch1 = o->branch2;
 848                         branch2 = o->branch1;
 849                         tmp = ren2;
 850                         ren2 = ren1;
 851                         ren1 = tmp;
 852                 }
 853                 src = ren1->pair->one->path;
 854
 855                 ren1->dst_entry->processed = 1;
 856                 ren1->src_entry->processed = 1;
 857
 858                 if (ren1->processed)
 859                         continue;
 860                 ren1->processed = 1;
 861
 862                 ren1_src = ren1->pair->one->path;
 863                 ren1_dst = ren1->pair->two->path;
 864
 865                 if (ren2) {
 866                         const char *ren2_src = ren2->pair->one->path;
 867                         const char *ren2_dst = ren2->pair->two->path;
 868                         /* Renamed in 1 and renamed in 2 */
 869                         if (strcmp(ren1_src, ren2_src) != 0)
 870                                 die("ren1.src != ren2.src");
 871                         ren2->dst_entry->processed = 1;
 872                         ren2->processed = 1;
 873                         if (strcmp(ren1_dst, ren2_dst) != 0) {
 874                                 clean_merge = 0;
 875                                 output(o, 1, "CONFLICT (rename/rename): "
 876                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
 877                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
 878                                        src, ren1_dst, branch1,
 879                                        src, ren2_dst, branch2,
 880                                        o->call_depth ? " (left unresolved)": "");
 881                                 if (o->call_depth) {
 882                                         remove_file_from_cache(src);
 883                                         update_file(o, 0, ren1->pair->one->sha1,
 884                                                     ren1->pair->one->mode, src);
 885                                 }
 886                                 conflict_rename_rename(o, ren1, branch1, ren2, branch2);
 887                         } else {
 888                                 struct merge_file_info mfi;
 889                                 remove_file(o, 1, ren1_src, 1);
 890                                 mfi = merge_file(o,
 891                                                  ren1->pair->one,
 892                                                  ren1->pair->two,
 893                                                  ren2->pair->two,
 894                                                  branch1,
 895                                                  branch2);
 896                                 if (mfi.merge || !mfi.clean)
 897                                         output(o, 1, "Renaming %s->%s", src, ren1_dst);
 898
 899                                 if (mfi.merge)
 900                                         output(o, 2, "Auto-merging %s", ren1_dst);
 901
 902                                 if (!mfi.clean) {
 903                                         output(o, 1, "CONFLICT (content): merge conflict in %s",
 904                                                ren1_dst);
 905                                         clean_merge = 0;
 906
 907                                         if (!o->call_depth)
 908                                                 update_stages(ren1_dst,
 909                                                               ren1->pair->one,
 910                                                               ren1->pair->two,
 911                                                               ren2->pair->two,
 912                                                               1 /* clear */);
 913                                 }
 914                                 update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 915                         }
 916                 } else {
 917                         /* Renamed in 1, maybe changed in 2 */
 918                         struct string_list_item *item;
 919                         /* we only use sha1 and mode of these */
 920                         struct diff_filespec src_other, dst_other;
 921                         int try_merge, stage = a_renames == renames1 ? 3: 2;
 922
 923                         remove_file(o, 1, ren1_src, o->call_depth || stage == 3);
 924
 925                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
 926                         src_other.mode = ren1->src_entry->stages[stage].mode;
 927                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
 928                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
 929
 930                         try_merge = 0;
 931
 932                         if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
 933                                 clean_merge = 0;
 934                                 output(o, 1, "CONFLICT (rename/directory): Rename %s->%s in %s "
 935                                        " directory %s added in %s",
 936                                        ren1_src, ren1_dst, branch1,
 937                                        ren1_dst, branch2);
 938                                 conflict_rename_dir(o, ren1, branch1);
 939                         } else if (sha_eq(src_other.sha1, null_sha1)) {
 940                                 clean_merge = 0;
 941                                 output(o, 1, "CONFLICT (rename/delete): Rename %s->%s in %s "
 942                                        "and deleted in %s",
 943                                        ren1_src, ren1_dst, branch1,
 944                                        branch2);
 945                                 update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
 946                                 if (!o->call_depth)
 947                                         update_stages(ren1_dst, NULL,
 948                                                         branch1 == o->branch1 ?
 949                                                         ren1->pair->two : NULL,
 950                                                         branch1 == o->branch1 ?
 951                                                         NULL : ren1->pair->two, 1);
 952                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
 953                                 const char *new_path;
 954                                 clean_merge = 0;
 955                                 try_merge = 1;
 956                                 output(o, 1, "CONFLICT (rename/add): Rename %s->%s in %s. "
 957                                        "%s added in %s",
 958                                        ren1_src, ren1_dst, branch1,
 959                                        ren1_dst, branch2);
 960                                 if (o->call_depth) {
 961                                         struct merge_file_info mfi;
 962                                         struct diff_filespec one, a, b;
 963
 964                                         one.path = a.path = b.path =
 965                                                 (char *)ren1_dst;
 966                                         hashcpy(one.sha1, null_sha1);
 967                                         one.mode = 0;
 968                                         hashcpy(a.sha1, ren1->pair->two->sha1);
 969                                         a.mode = ren1->pair->two->mode;
 970                                         hashcpy(b.sha1, dst_other.sha1);
 971                                         b.mode = dst_other.mode;
 972                                         mfi = merge_file(o, &one, &a, &b,
 973                                                          branch1,
 974                                                          branch2);
 975                                         output(o, 1, "Adding merged %s", ren1_dst);
 976                                         update_file(o, 0,
 977                                                     mfi.sha,
 978                                                     mfi.mode,
 979                                                     ren1_dst);
 980                                 } else {
 981                                         new_path = unique_path(o, ren1_dst, branch2);
 982                                         output(o, 1, "Adding as %s instead", new_path);
 983                                         update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
 984                                 }
 985                         } else if ((item = string_list_lookup(renames2Dst, ren1_dst))) {
 986                                 ren2 = item->util;
 987                                 clean_merge = 0;
 988                                 ren2->processed = 1;
 989                                 output(o, 1, "CONFLICT (rename/rename): "
 990                                        "Rename %s->%s in %s. "
 991                                        "Rename %s->%s in %s",
 992                                        ren1_src, ren1_dst, branch1,
 993                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
 994                                 conflict_rename_rename_2(o, ren1, branch1, ren2, branch2);
 995                         } else
 996                                 try_merge = 1;
 997
 998                         if (try_merge) {
 999                                 struct diff_filespec *one, *a, *b;
1000                                 struct merge_file_info mfi;
1001                                 src_other.path = (char *)ren1_src;
1002
1003                                 one = ren1->pair->one;
1004                                 if (a_renames == renames1) {
1005                                         a = ren1->pair->two;
1006                                         b = &src_other;
1007                                 } else {
1008                                         b = ren1->pair->two;
1009                                         a = &src_other;
1010                                 }
1011                                 mfi = merge_file(o, one, a, b,
1012                                                 o->branch1, o->branch2);
1013
1014                                 if (mfi.clean &&
1015                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
1016                                     mfi.mode == ren1->pair->two->mode)
1017                                         /*
1018                                          * This messaged is part of
1019                                          * t6022 test. If you change
1020                                          * it update the test too.
1021                                          */
1022                                         output(o, 3, "Skipped %s (merged same as existing)", ren1_dst);
1023                                 else {
1024                                         if (mfi.merge || !mfi.clean)
1025                                                 output(o, 1, "Renaming %s => %s", ren1_src, ren1_dst);
1026                                         if (mfi.merge)
1027                                                 output(o, 2, "Auto-merging %s", ren1_dst);
1028                                         if (!mfi.clean) {
1029                                                 output(o, 1, "CONFLICT (rename/modify): Merge conflict in %s",
1030                                                        ren1_dst);
1031                                                 clean_merge = 0;
1032
1033                                                 if (!o->call_depth)
1034                                                         update_stages(ren1_dst,
1035                                                                       one, a, b, 1);
1036                                         }
1037                                         update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1038                                 }
1039                         }
1040                 }
1041         }
1042         string_list_clear(&a_by_dst, 0);
1043         string_list_clear(&b_by_dst, 0);
1044
1045         return clean_merge;
1046 }
1047
1048 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1049 {
1050         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1051 }
1052
1053 /* Per entry merge function */
1054 static int process_entry(struct merge_options *o,
1055                          const char *path, struct stage_data *entry)
1056 {
1057         /*
1058         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1059         print_index_entry("\tpath: ", entry);
1060         */
1061         int clean_merge = 1;
1062         unsigned o_mode = entry->stages[1].mode;
1063         unsigned a_mode = entry->stages[2].mode;
1064         unsigned b_mode = entry->stages[3].mode;
1065         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1066         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1067         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1068
1069         if (o_sha && (!a_sha || !b_sha)) {
1070                 /* Case A: Deleted in one */
1071                 if ((!a_sha && !b_sha) ||
1072                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1073                     (!a_sha && sha_eq(b_sha, o_sha))) {
1074                         /* Deleted in both or deleted in one and
1075                          * unchanged in the other */
1076                         if (a_sha)
1077                                 output(o, 2, "Removing %s", path);
1078                         /* do not touch working file if it did not exist */
1079                         remove_file(o, 1, path, !a_sha);
1080                 } else {
1081                         /* Deleted in one and changed in the other */
1082                         clean_merge = 0;
1083                         if (!a_sha) {
1084                                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1085                                        "and modified in %s. Version %s of %s left in tree.",
1086                                        path, o->branch1,
1087                                        o->branch2, o->branch2, path);
1088                                 update_file(o, 0, b_sha, b_mode, path);
1089                         } else {
1090                                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1091                                        "and modified in %s. Version %s of %s left in tree.",
1092                                        path, o->branch2,
1093                                        o->branch1, o->branch1, path);
1094                                 update_file(o, 0, a_sha, a_mode, path);
1095                         }
1096                 }
1097
1098         } else if ((!o_sha && a_sha && !b_sha) ||
1099                    (!o_sha && !a_sha && b_sha)) {
1100                 /* Case B: Added in one. */
1101                 const char *add_branch;
1102                 const char *other_branch;
1103                 unsigned mode;
1104                 const unsigned char *sha;
1105                 const char *conf;
1106
1107                 if (a_sha) {
1108                         add_branch = o->branch1;
1109                         other_branch = o->branch2;
1110                         mode = a_mode;
1111                         sha = a_sha;
1112                         conf = "file/directory";
1113                 } else {
1114                         add_branch = o->branch2;
1115                         other_branch = o->branch1;
1116                         mode = b_mode;
1117                         sha = b_sha;
1118                         conf = "directory/file";
1119                 }
1120                 if (string_list_has_string(&o->current_directory_set, path)) {
1121                         const char *new_path = unique_path(o, path, add_branch);
1122                         clean_merge = 0;
1123                         output(o, 1, "CONFLICT (%s): There is a directory with name %s in %s. "
1124                                "Adding %s as %s",
1125                                conf, path, other_branch, path, new_path);
1126                         remove_file(o, 0, path, 0);
1127                         update_file(o, 0, sha, mode, new_path);
1128                 } else {
1129                         output(o, 2, "Adding %s", path);
1130                         update_file(o, 1, sha, mode, path);
1131                 }
1132         } else if (a_sha && b_sha) {
1133                 /* Case C: Added in both (check for same permissions) and */
1134                 /* case D: Modified in both, but differently. */
1135                 const char *reason = "content";
1136                 struct merge_file_info mfi;
1137                 struct diff_filespec one, a, b;
1138
1139                 if (!o_sha) {
1140                         reason = "add/add";
1141                         o_sha = (unsigned char *)null_sha1;
1142                 }
1143                 output(o, 2, "Auto-merging %s", path);
1144                 one.path = a.path = b.path = (char *)path;
1145                 hashcpy(one.sha1, o_sha);
1146                 one.mode = o_mode;
1147                 hashcpy(a.sha1, a_sha);
1148                 a.mode = a_mode;
1149                 hashcpy(b.sha1, b_sha);
1150                 b.mode = b_mode;
1151
1152                 mfi = merge_file(o, &one, &a, &b,
1153                                  o->branch1, o->branch2);
1154
1155                 clean_merge = mfi.clean;
1156                 if (!mfi.clean) {
1157                         if (S_ISGITLINK(mfi.mode))
1158                                 reason = "submodule";
1159                         output(o, 1, "CONFLICT (%s): Merge conflict in %s",
1160                                         reason, path);
1161                 }
1162                 update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
1163         } else if (!o_sha && !a_sha && !b_sha) {
1164                 /*
1165                  * this entry was deleted altogether. a_mode == 0 means
1166                  * we had that path and want to actively remove it.
1167                  */
1168                 remove_file(o, 1, path, !a_mode);
1169         } else
1170                 die("Fatal merge failure, shouldn't happen.");
1171
1172         return clean_merge;
1173 }
1174
1175 struct unpack_trees_error_msgs get_porcelain_error_msgs(void)
1176 {
1177         struct unpack_trees_error_msgs msgs = {
1178                 /* would_overwrite */
1179                 "Your local changes to '%s' would be overwritten by merge.  Aborting.",
1180                 /* not_uptodate_file */
1181                 "Your local changes to '%s' would be overwritten by merge.  Aborting.",
1182                 /* not_uptodate_dir */
1183                 "Updating '%s' would lose untracked files in it.  Aborting.",
1184                 /* would_lose_untracked */
1185                 "Untracked working tree file '%s' would be %s by merge.  Aborting",
1186                 /* bind_overlap -- will not happen here */
1187                 NULL,
1188         };
1189         if (advice_commit_before_merge) {
1190                 msgs.would_overwrite = msgs.not_uptodate_file =
1191                         "Your local changes to '%s' would be overwritten by merge.  Aborting.\n"
1192                         "Please, commit your changes or stash them before you can merge.";
1193         }
1194         return msgs;
1195 }
1196
1197 int merge_trees(struct merge_options *o,
1198                 struct tree *head,
1199                 struct tree *merge,
1200                 struct tree *common,
1201                 struct tree **result)
1202 {
1203         int code, clean;
1204
1205         if (o->subtree_shift) {
1206                 merge = shift_tree_object(head, merge, o->subtree_shift);
1207                 common = shift_tree_object(head, common, o->subtree_shift);
1208         }
1209
1210         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1211                 output(o, 0, "Already up-to-date!");
1212                 *result = head;
1213                 return 1;
1214         }
1215
1216         code = git_merge_trees(o->call_depth, common, head, merge);
1217
1218         if (code != 0) {
1219                 if (show(o, 4) || o->call_depth)
1220                         die("merging of trees %s and %s failed",
1221                             sha1_to_hex(head->object.sha1),
1222                             sha1_to_hex(merge->object.sha1));
1223                 else
1224                         exit(128);
1225         }
1226
1227         if (unmerged_cache()) {
1228                 struct string_list *entries, *re_head, *re_merge;
1229                 int i;
1230                 string_list_clear(&o->current_file_set, 1);
1231                 string_list_clear(&o->current_directory_set, 1);
1232                 get_files_dirs(o, head);
1233                 get_files_dirs(o, merge);
1234
1235                 entries = get_unmerged();
1236                 re_head  = get_renames(o, head, common, head, merge, entries);
1237                 re_merge = get_renames(o, merge, common, head, merge, entries);
1238                 clean = process_renames(o, re_head, re_merge);
1239                 for (i = 0; i < entries->nr; i++) {
1240                         const char *path = entries->items[i].string;
1241                         struct stage_data *e = entries->items[i].util;
1242                         if (!e->processed
1243                                 && !process_entry(o, path, e))
1244                                 clean = 0;
1245                 }
1246
1247                 string_list_clear(re_merge, 0);
1248                 string_list_clear(re_head, 0);
1249                 string_list_clear(entries, 1);
1250
1251         }
1252         else
1253                 clean = 1;
1254
1255         if (o->call_depth)
1256                 *result = write_tree_from_memory(o);
1257
1258         return clean;
1259 }
1260
1261 static struct commit_list *reverse_commit_list(struct commit_list *list)
1262 {
1263         struct commit_list *next = NULL, *current, *backup;
1264         for (current = list; current; current = backup) {
1265                 backup = current->next;
1266                 current->next = next;
1267                 next = current;
1268         }
1269         return next;
1270 }
1271
1272 /*
1273  * Merge the commits h1 and h2, return the resulting virtual
1274  * commit object and a flag indicating the cleanness of the merge.
1275  */
1276 int merge_recursive(struct merge_options *o,
1277                     struct commit *h1,
1278                     struct commit *h2,
1279                     struct commit_list *ca,
1280                     struct commit **result)
1281 {
1282         struct commit_list *iter;
1283         struct commit *merged_common_ancestors;
1284         struct tree *mrtree = mrtree;
1285         int clean;
1286
1287         if (show(o, 4)) {
1288                 output(o, 4, "Merging:");
1289                 output_commit_title(o, h1);
1290                 output_commit_title(o, h2);
1291         }
1292
1293         if (!ca) {
1294                 ca = get_merge_bases(h1, h2, 1);
1295                 ca = reverse_commit_list(ca);
1296         }
1297
1298         if (show(o, 5)) {
1299                 output(o, 5, "found %u common ancestor(s):", commit_list_count(ca));
1300                 for (iter = ca; iter; iter = iter->next)
1301                         output_commit_title(o, iter->item);
1302         }
1303
1304         merged_common_ancestors = pop_commit(&ca);
1305         if (merged_common_ancestors == NULL) {
1306                 /* if there is no common ancestor, make an empty tree */
1307                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1308
1309                 tree->object.parsed = 1;
1310                 tree->object.type = OBJ_TREE;
1311                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1312                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1313         }
1314
1315         for (iter = ca; iter; iter = iter->next) {
1316                 const char *saved_b1, *saved_b2;
1317                 o->call_depth++;
1318                 /*
1319                  * When the merge fails, the result contains files
1320                  * with conflict markers. The cleanness flag is
1321                  * ignored, it was never actually used, as result of
1322                  * merge_trees has always overwritten it: the committed
1323                  * "conflicts" were already resolved.
1324                  */
1325                 discard_cache();
1326                 saved_b1 = o->branch1;
1327                 saved_b2 = o->branch2;
1328                 o->branch1 = "Temporary merge branch 1";
1329                 o->branch2 = "Temporary merge branch 2";
1330                 merge_recursive(o, merged_common_ancestors, iter->item,
1331                                 NULL, &merged_common_ancestors);
1332                 o->branch1 = saved_b1;
1333                 o->branch2 = saved_b2;
1334                 o->call_depth--;
1335
1336                 if (!merged_common_ancestors)
1337                         die("merge returned no commit");
1338         }
1339
1340         discard_cache();
1341         if (!o->call_depth)
1342                 read_cache();
1343
1344         o->ancestor = "merged common ancestors";
1345         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
1346                             &mrtree);
1347
1348         if (o->call_depth) {
1349                 *result = make_virtual_commit(mrtree, "merged tree");
1350                 commit_list_insert(h1, &(*result)->parents);
1351                 commit_list_insert(h2, &(*result)->parents->next);
1352         }
1353         flush_output(o);
1354         return clean;
1355 }
1356
1357 static struct commit *get_ref(const unsigned char *sha1, const char *name)
1358 {
1359         struct object *object;
1360
1361         object = deref_tag(parse_object(sha1), name, strlen(name));
1362         if (!object)
1363                 return NULL;
1364         if (object->type == OBJ_TREE)
1365                 return make_virtual_commit((struct tree*)object, name);
1366         if (object->type != OBJ_COMMIT)
1367                 return NULL;
1368         if (parse_commit((struct commit *)object))
1369                 return NULL;
1370         return (struct commit *)object;
1371 }
1372
1373 int merge_recursive_generic(struct merge_options *o,
1374                             const unsigned char *head,
1375                             const unsigned char *merge,
1376                             int num_base_list,
1377                             const unsigned char **base_list,
1378                             struct commit **result)
1379 {
1380         int clean, index_fd;
1381         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1382         struct commit *head_commit = get_ref(head, o->branch1);
1383         struct commit *next_commit = get_ref(merge, o->branch2);
1384         struct commit_list *ca = NULL;
1385
1386         if (base_list) {
1387                 int i;
1388                 for (i = 0; i < num_base_list; ++i) {
1389                         struct commit *base;
1390                         if (!(base = get_ref(base_list[i], sha1_to_hex(base_list[i]))))
1391                                 return error("Could not parse object '%s'",
1392                                         sha1_to_hex(base_list[i]));
1393                         commit_list_insert(base, &ca);
1394                 }
1395         }
1396
1397         index_fd = hold_locked_index(lock, 1);
1398         clean = merge_recursive(o, head_commit, next_commit, ca,
1399                         result);
1400         if (active_cache_changed &&
1401                         (write_cache(index_fd, active_cache, active_nr) ||
1402                          commit_locked_index(lock)))
1403                 return error("Unable to write index.");
1404
1405         return clean ? 0 : 1;
1406 }
1407
1408 static int merge_recursive_config(const char *var, const char *value, void *cb)
1409 {
1410         struct merge_options *o = cb;
1411         if (!strcasecmp(var, "merge.verbosity")) {
1412                 o->verbosity = git_config_int(var, value);
1413                 return 0;
1414         }
1415         if (!strcasecmp(var, "diff.renamelimit")) {
1416                 o->diff_rename_limit = git_config_int(var, value);
1417                 return 0;
1418         }
1419         if (!strcasecmp(var, "merge.renamelimit")) {
1420                 o->merge_rename_limit = git_config_int(var, value);
1421                 return 0;
1422         }
1423         return git_xmerge_config(var, value, cb);
1424 }
1425
1426 void init_merge_options(struct merge_options *o)
1427 {
1428         memset(o, 0, sizeof(struct merge_options));
1429         o->verbosity = 2;
1430         o->buffer_output = 1;
1431         o->diff_rename_limit = -1;
1432         o->merge_rename_limit = -1;
1433         git_config(merge_recursive_config, o);
1434         if (getenv("GIT_MERGE_VERBOSITY"))
1435                 o->verbosity =
1436                         strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1437         if (o->verbosity >= 5)
1438                 o->buffer_output = 0;
1439         strbuf_init(&o->obuf, 0);
1440         memset(&o->current_file_set, 0, sizeof(struct string_list));
1441         o->current_file_set.strdup_strings = 1;
1442         memset(&o->current_directory_set, 0, sizeof(struct string_list));
1443         o->current_directory_set.strdup_strings = 1;
1444 }