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 *s;
 140                         int len;
 141                         for (s = commit->buffer; *s; s++)
 142                                 if (*s == '\n' && s[1] == '\n') {
 143                                         s += 2;
 144                                         break;
 145                                 }
 146                         for (len = 0; s[len] && '\n' != s[len]; len++)
 147                                 ; /* do nothing */
 148                         printf("%.*s\n", len, s);
 149                 }
 150         }
 151 }
 152
 153 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 154                 const char *path, int stage, int refresh, int options)
 155 {
 156         struct cache_entry *ce;
 157         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 158         if (!ce)
 159                 return error("addinfo_cache failed for path '%s'", path);
 160         return add_cache_entry(ce, options);
 161 }
 162
 163 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 164 {
 165         parse_tree(tree);
 166         init_tree_desc(desc, tree->buffer, tree->size);
 167 }
 168
 169 static int git_merge_trees(int index_only,
 170                            struct tree *common,
 171                            struct tree *head,
 172                            struct tree *merge)
 173 {
 174         int rc;
 175         struct tree_desc t[3];
 176         struct unpack_trees_options opts;
 177
 178         memset(&opts, 0, sizeof(opts));
 179         if (index_only)
 180                 opts.index_only = 1;
 181         else
 182                 opts.update = 1;
 183         opts.merge = 1;
 184         opts.head_idx = 2;
 185         opts.fn = threeway_merge;
 186         opts.src_index = &the_index;
 187         opts.dst_index = &the_index;
 188         opts.msgs = get_porcelain_error_msgs();
 189
 190         init_tree_desc_from_tree(t+0, common);
 191         init_tree_desc_from_tree(t+1, head);
 192         init_tree_desc_from_tree(t+2, merge);
 193
 194         rc = unpack_trees(3, t, &opts);
 195         cache_tree_free(&active_cache_tree);
 196         return rc;
 197 }
 198
 199 struct tree *write_tree_from_memory(struct merge_options *o)
 200 {
 201         struct tree *result = NULL;
 202
 203         if (unmerged_cache()) {
 204                 int i;
 205                 fprintf(stderr, "BUG: There are unmerged index entries:\n");
 206                 for (i = 0; i < active_nr; i++) {
 207                         struct cache_entry *ce = active_cache[i];
 208                         if (ce_stage(ce))
 209                                 fprintf(stderr, "BUG: %d %.*s", ce_stage(ce),
 210                                         (int)ce_namelen(ce), ce->name);
 211                 }
 212                 die("Bug in merge-recursive.c");
 213         }
 214
 215         if (!active_cache_tree)
 216                 active_cache_tree = cache_tree();
 217
 218         if (!cache_tree_fully_valid(active_cache_tree) &&
 219             cache_tree_update(active_cache_tree,
 220                               active_cache, active_nr, 0, 0) < 0)
 221                 die("error building trees");
 222
 223         result = lookup_tree(active_cache_tree->sha1);
 224
 225         return result;
 226 }
 227
 228 static int save_files_dirs(const unsigned char *sha1,
 229                 const char *base, int baselen, const char *path,
 230                 unsigned int mode, int stage, void *context)
 231 {
 232         int len = strlen(path);
 233         char *newpath = xmalloc(baselen + len + 1);
 234         struct merge_options *o = context;
 235
 236         memcpy(newpath, base, baselen);
 237         memcpy(newpath + baselen, path, len);
 238         newpath[baselen + len] = '\0';
 239
 240         if (S_ISDIR(mode))
 241                 string_list_insert(newpath, &o->current_directory_set);
 242         else
 243                 string_list_insert(newpath, &o->current_file_set);
 244         free(newpath);
 245
 246         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
 247 }
 248
 249 static int get_files_dirs(struct merge_options *o, struct tree *tree)
 250 {
 251         int n;
 252         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs, o))
 253                 return 0;
 254         n = o->current_file_set.nr + o->current_directory_set.nr;
 255         return n;
 256 }
 257
 258 /*
 259  * Returns an index_entry instance which doesn't have to correspond to
 260  * a real cache entry in Git's index.
 261  */
 262 static struct stage_data *insert_stage_data(const char *path,
 263                 struct tree *o, struct tree *a, struct tree *b,
 264                 struct string_list *entries)
 265 {
 266         struct string_list_item *item;
 267         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 268         get_tree_entry(o->object.sha1, path,
 269                         e->stages[1].sha, &e->stages[1].mode);
 270         get_tree_entry(a->object.sha1, path,
 271                         e->stages[2].sha, &e->stages[2].mode);
 272         get_tree_entry(b->object.sha1, path,
 273                         e->stages[3].sha, &e->stages[3].mode);
 274         item = string_list_insert(path, entries);
 275         item->util = e;
 276         return e;
 277 }
 278
 279 /*
 280  * Create a dictionary mapping file names to stage_data objects. The
 281  * dictionary contains one entry for every path with a non-zero stage entry.
 282  */
 283 static struct string_list *get_unmerged(void)
 284 {
 285         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
 286         int i;
 287
 288         unmerged->strdup_strings = 1;
 289
 290         for (i = 0; i < active_nr; i++) {
 291                 struct string_list_item *item;
 292                 struct stage_data *e;
 293                 struct cache_entry *ce = active_cache[i];
 294                 if (!ce_stage(ce))
 295                         continue;
 296
 297                 item = string_list_lookup(ce->name, unmerged);
 298                 if (!item) {
 299                         item = string_list_insert(ce->name, unmerged);
 300                         item->util = xcalloc(1, sizeof(struct stage_data));
 301                 }
 302                 e = item->util;
 303                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
 304                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 305         }
 306
 307         return unmerged;
 308 }
 309
 310 struct rename
 311 {
 312         struct diff_filepair *pair;
 313         struct stage_data *src_entry;
 314         struct stage_data *dst_entry;
 315         unsigned processed:1;
 316 };
 317
 318 /*
 319  * Get information of all renames which occurred between 'o_tree' and
 320  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 321  * 'b_tree') to be able to associate the correct cache entries with
 322  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 323  */
 324 static struct string_list *get_renames(struct merge_options *o,
 325                                        struct tree *tree,
 326                                        struct tree *o_tree,
 327                                        struct tree *a_tree,
 328                                        struct tree *b_tree,
 329                                        struct string_list *entries)
 330 {
 331         int i;
 332         struct string_list *renames;
 333         struct diff_options opts;
 334
 335         renames = xcalloc(1, sizeof(struct string_list));
 336         diff_setup(&opts);
 337         DIFF_OPT_SET(&opts, RECURSIVE);
 338         opts.detect_rename = DIFF_DETECT_RENAME;
 339         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 340                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 341                             500;
 342         opts.warn_on_too_large_rename = 1;
 343         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 344         if (diff_setup_done(&opts) < 0)
 345                 die("diff setup failed");
 346         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 347         diffcore_std(&opts);
 348         for (i = 0; i < diff_queued_diff.nr; ++i) {
 349                 struct string_list_item *item;
 350                 struct rename *re;
 351                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 352                 if (pair->status != 'R') {
 353                         diff_free_filepair(pair);
 354                         continue;
 355                 }
 356                 re = xmalloc(sizeof(*re));
 357                 re->processed = 0;
 358                 re->pair = pair;
 359                 item = string_list_lookup(re->pair->one->path, entries);
 360                 if (!item)
 361                         re->src_entry = insert_stage_data(re->pair->one->path,
 362                                         o_tree, a_tree, b_tree, entries);
 363                 else
 364                         re->src_entry = item->util;
 365
 366                 item = string_list_lookup(re->pair->two->path, entries);
 367                 if (!item)
 368                         re->dst_entry = insert_stage_data(re->pair->two->path,
 369                                         o_tree, a_tree, b_tree, entries);
 370                 else
 371                         re->dst_entry = item->util;
 372                 item = string_list_insert(pair->one->path, renames);
 373                 item->util = re;
 374         }
 375         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 376         diff_queued_diff.nr = 0;
 377         diff_flush(&opts);
 378         return renames;
 379 }
 380
 381 static int update_stages(const char *path, struct diff_filespec *o,
 382                          struct diff_filespec *a, struct diff_filespec *b,
 383                          int clear)
 384 {
 385         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 386         if (clear)
 387                 if (remove_file_from_cache(path))
 388                         return -1;
 389         if (o)
 390                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 391                         return -1;
 392         if (a)
 393                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 394                         return -1;
 395         if (b)
 396                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 397                         return -1;
 398         return 0;
 399 }
 400
 401 static int remove_file(struct merge_options *o, int clean,
 402                        const char *path, int no_wd)
 403 {
 404         int update_cache = o->call_depth || clean;
 405         int update_working_directory = !o->call_depth && !no_wd;
 406
 407         if (update_cache) {
 408                 if (remove_file_from_cache(path))
 409                         return -1;
 410         }
 411         if (update_working_directory) {
 412                 if (remove_path(path))
 413                         return -1;
 414         }
 415         return 0;
 416 }
 417
 418 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
 419 {
 420         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 421         int suffix = 0;
 422         struct stat st;
 423         char *p = newpath + strlen(path);
 424         strcpy(newpath, path);
 425         *(p++) = '~';
 426         strcpy(p, branch);
 427         for (; *p; ++p)
 428                 if ('/' == *p)
 429                         *p = '_';
 430         while (string_list_has_string(&o->current_file_set, newpath) ||
 431                string_list_has_string(&o->current_directory_set, newpath) ||
 432                lstat(newpath, &st) == 0)
 433                 sprintf(p, "_%d", suffix++);
 434
 435         string_list_insert(newpath, &o->current_file_set);
 436         return newpath;
 437 }
 438
 439 static void flush_buffer(int fd, const char *buf, unsigned long size)
 440 {
 441         while (size > 0) {
 442                 long ret = write_in_full(fd, buf, size);
 443                 if (ret < 0) {
 444                         /* Ignore epipe */
 445                         if (errno == EPIPE)
 446                                 break;
 447                         die_errno("merge-recursive");
 448                 } else if (!ret) {
 449                         die("merge-recursive: disk full?");
 450                 }
 451                 size -= ret;
 452                 buf += ret;
 453         }
 454 }
 455
 456 static int would_lose_untracked(const char *path)
 457 {
 458         int pos = cache_name_pos(path, strlen(path));
 459
 460         if (pos < 0)
 461                 pos = -1 - pos;
 462         while (pos < active_nr &&
 463                !strcmp(path, active_cache[pos]->name)) {
 464                 /*
 465                  * If stage #0, it is definitely tracked.
 466                  * If it has stage #2 then it was tracked
 467                  * before this merge started.  All other
 468                  * cases the path was not tracked.
 469                  */
 470                 switch (ce_stage(active_cache[pos])) {
 471                 case 0:
 472                 case 2:
 473                         return 0;
 474                 }
 475                 pos++;
 476         }
 477         return file_exists(path);
 478 }
 479
 480 static int make_room_for_path(const char *path)
 481 {
 482         int status;
 483         const char *msg = "failed to create path '%s'%s";
 484
 485         status = safe_create_leading_directories_const(path);
 486         if (status) {
 487                 if (status == -3) {
 488                         /* something else exists */
 489                         error(msg, path, ": perhaps a D/F conflict?");
 490                         return -1;
 491                 }
 492                 die(msg, path, "");
 493         }
 494
 495         /*
 496          * Do not unlink a file in the work tree if we are not
 497          * tracking it.
 498          */
 499         if (would_lose_untracked(path))
 500                 return error("refusing to lose untracked file at '%s'",
 501                              path);
 502
 503         /* Successful unlink is good.. */
 504         if (!unlink(path))
 505                 return 0;
 506         /* .. and so is no existing file */
 507         if (errno == ENOENT)
 508                 return 0;
 509         /* .. but not some other error (who really cares what?) */
 510         return error(msg, path, ": perhaps a D/F conflict?");
 511 }
 512
 513 static void update_file_flags(struct merge_options *o,
 514                               const unsigned char *sha,
 515                               unsigned mode,
 516                               const char *path,
 517                               int update_cache,
 518                               int update_wd)
 519 {
 520         if (o->call_depth)
 521                 update_wd = 0;
 522
 523         if (update_wd) {
 524                 enum object_type type;
 525                 void *buf;
 526                 unsigned long size;
 527
 528                 if (S_ISGITLINK(mode))
 529                         /*
 530                          * We may later decide to recursively descend into
 531                          * the submodule directory and update its index
 532                          * and/or work tree, but we do not do that now.
 533                          */
 534                         goto update_index;
 535
 536                 buf = read_sha1_file(sha, &type, &size);
 537                 if (!buf)
 538                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 539                 if (type != OBJ_BLOB)
 540                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 541                 if (S_ISREG(mode)) {
 542                         struct strbuf strbuf = STRBUF_INIT;
 543                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
 544                                 free(buf);
 545                                 size = strbuf.len;
 546                                 buf = strbuf_detach(&strbuf, NULL);
 547                         }
 548                 }
 549
 550                 if (make_room_for_path(path) < 0) {
 551                         update_wd = 0;
 552                         free(buf);
 553                         goto update_index;
 554                 }
 555                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 556                         int fd;
 557                         if (mode & 0100)
 558                                 mode = 0777;
 559                         else
 560                                 mode = 0666;
 561                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 562                         if (fd < 0)
 563                                 die_errno("failed to open '%s'", path);
 564                         flush_buffer(fd, buf, size);
 565                         close(fd);
 566                 } else if (S_ISLNK(mode)) {
 567                         char *lnk = xmemdupz(buf, size);
 568                         safe_create_leading_directories_const(path);
 569                         unlink(path);
 570                         if (symlink(lnk, path))
 571                                 die_errno("failed to symlink '%s'", path);
 572                         free(lnk);
 573                 } else
 574                         die("do not know what to do with %06o %s '%s'",
 575                             mode, sha1_to_hex(sha), path);
 576                 free(buf);
 577         }
 578  update_index:
 579         if (update_cache)
 580                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 581 }
 582
 583 static void update_file(struct merge_options *o,
 584                         int clean,
 585                         const unsigned char *sha,
 586                         unsigned mode,
 587                         const char *path)
 588 {
 589         update_file_flags(o, sha, mode, path, o->call_depth || clean, !o->call_depth);
 590 }
 591
 592 /* Low level file merging, update and removal */
 593
 594 struct merge_file_info
 595 {
 596         unsigned char sha[20];
 597         unsigned mode;
 598         unsigned clean:1,
 599                  merge:1;
 600 };
 601
 602 static int merge_3way(struct merge_options *o,
 603                       mmbuffer_t *result_buf,
 604                       struct diff_filespec *one,
 605                       struct diff_filespec *a,
 606                       struct diff_filespec *b,
 607                       const char *branch1,
 608                       const char *branch2)
 609 {
 610         mmfile_t orig, src1, src2;
 611         char *base_name, *name1, *name2;
 612         int merge_status;
 613         int favor;
 614
 615         if (o->call_depth)
 616                 favor = 0;
 617         else {
 618                 switch (o->recursive_variant) {
 619                 case MERGE_RECURSIVE_OURS:
 620                         favor = XDL_MERGE_FAVOR_OURS;
 621                         break;
 622                 case MERGE_RECURSIVE_THEIRS:
 623                         favor = XDL_MERGE_FAVOR_THEIRS;
 624                         break;
 625                 default:
 626                         favor = 0;
 627                         break;
 628                 }
 629         }
 630
 631         if (strcmp(a->path, b->path) ||
 632             (o->ancestor != NULL && strcmp(a->path, one->path) != 0)) {
 633                 base_name = o->ancestor == NULL ? NULL :
 634                         xstrdup(mkpath("%s:%s", o->ancestor, one->path));
 635                 name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 636                 name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 637         } else {
 638                 base_name = o->ancestor == NULL ? NULL :
 639                         xstrdup(mkpath("%s", o->ancestor));
 640                 name1 = xstrdup(mkpath("%s", branch1));
 641                 name2 = xstrdup(mkpath("%s", branch2));
 642         }
 643
 644         read_mmblob(&orig, one->sha1);
 645         read_mmblob(&src1, a->sha1);
 646         read_mmblob(&src2, b->sha1);
 647
 648         merge_status = ll_merge(result_buf, a->path, &orig, base_name,
 649                                 &src1, name1, &src2, name2,
 650                                 (!!o->call_depth) | (favor << 1));
 651
 652         free(name1);
 653         free(name2);
 654         free(orig.ptr);
 655         free(src1.ptr);
 656         free(src2.ptr);
 657         return merge_status;
 658 }
 659
 660 static struct merge_file_info merge_file(struct merge_options *o,
 661                                          struct diff_filespec *one,
 662                                          struct diff_filespec *a,
 663                                          struct diff_filespec *b,
 664                                          const char *branch1,
 665                                          const char *branch2)
 666 {
 667         struct merge_file_info result;
 668         result.merge = 0;
 669         result.clean = 1;
 670
 671         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 672                 result.clean = 0;
 673                 if (S_ISREG(a->mode)) {
 674                         result.mode = a->mode;
 675                         hashcpy(result.sha, a->sha1);
 676                 } else {
 677                         result.mode = b->mode;
 678                         hashcpy(result.sha, b->sha1);
 679                 }
 680         } else {
 681                 if (!sha_eq(a->sha1, one->sha1) && !sha_eq(b->sha1, one->sha1))
 682                         result.merge = 1;
 683
 684                 /*
 685                  * Merge modes
 686                  */
 687                 if (a->mode == b->mode || a->mode == one->mode)
 688                         result.mode = b->mode;
 689                 else {
 690                         result.mode = a->mode;
 691                         if (b->mode != one->mode) {
 692                                 result.clean = 0;
 693                                 result.merge = 1;
 694                         }
 695                 }
 696
 697                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, one->sha1))
 698                         hashcpy(result.sha, b->sha1);
 699                 else if (sha_eq(b->sha1, one->sha1))
 700                         hashcpy(result.sha, a->sha1);
 701                 else if (S_ISREG(a->mode)) {
 702                         mmbuffer_t result_buf;
 703                         int merge_status;
 704
 705                         merge_status = merge_3way(o, &result_buf, one, a, b,
 706                                                   branch1, branch2);
 707
 708                         if ((merge_status < 0) || !result_buf.ptr)
 709                                 die("Failed to execute internal merge");
 710
 711                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 712                                             blob_type, result.sha))
 713                                 die("Unable to add %s to database",
 714                                     a->path);
 715
 716                         free(result_buf.ptr);
 717                         result.clean = (merge_status == 0);
 718                 } else if (S_ISGITLINK(a->mode)) {
 719                         result.clean = 0;
 720                         hashcpy(result.sha, a->sha1);
 721                 } else if (S_ISLNK(a->mode)) {
 722                         hashcpy(result.sha, a->sha1);
 723
 724                         if (!sha_eq(a->sha1, b->sha1))
 725                                 result.clean = 0;
 726                 } else {
 727                         die("unsupported object type in the tree");
 728                 }
 729         }
 730
 731         return result;
 732 }
 733
 734 static void conflict_rename_rename(struct merge_options *o,
 735                                    struct rename *ren1,
 736                                    const char *branch1,
 737                                    struct rename *ren2,
 738                                    const char *branch2)
 739 {
 740         char *del[2];
 741         int delp = 0;
 742         const char *ren1_dst = ren1->pair->two->path;
 743         const char *ren2_dst = ren2->pair->two->path;
 744         const char *dst_name1 = ren1_dst;
 745         const char *dst_name2 = ren2_dst;
 746         if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
 747                 dst_name1 = del[delp++] = unique_path(o, ren1_dst, branch1);
 748                 output(o, 1, "%s is a directory in %s adding as %s instead",
 749                        ren1_dst, branch2, dst_name1);
 750                 remove_file(o, 0, ren1_dst, 0);
 751         }
 752         if (string_list_has_string(&o->current_directory_set, ren2_dst)) {
 753                 dst_name2 = del[delp++] = unique_path(o, ren2_dst, branch2);
 754                 output(o, 1, "%s is a directory in %s adding as %s instead",
 755                        ren2_dst, branch1, dst_name2);
 756                 remove_file(o, 0, ren2_dst, 0);
 757         }
 758         if (o->call_depth) {
 759                 remove_file_from_cache(dst_name1);
 760                 remove_file_from_cache(dst_name2);
 761                 /*
 762                  * Uncomment to leave the conflicting names in the resulting tree
 763                  *
 764                  * update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
 765                  * update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
 766                  */
 767         } else {
 768                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
 769                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
 770         }
 771         while (delp--)
 772                 free(del[delp]);
 773 }
 774
 775 static void conflict_rename_dir(struct merge_options *o,
 776                                 struct rename *ren1,
 777                                 const char *branch1)
 778 {
 779         char *new_path = unique_path(o, ren1->pair->two->path, branch1);
 780         output(o, 1, "Renaming %s to %s instead", ren1->pair->one->path, new_path);
 781         remove_file(o, 0, ren1->pair->two->path, 0);
 782         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
 783         free(new_path);
 784 }
 785
 786 static void conflict_rename_rename_2(struct merge_options *o,
 787                                      struct rename *ren1,
 788                                      const char *branch1,
 789                                      struct rename *ren2,
 790                                      const char *branch2)
 791 {
 792         char *new_path1 = unique_path(o, ren1->pair->two->path, branch1);
 793         char *new_path2 = unique_path(o, ren2->pair->two->path, branch2);
 794         output(o, 1, "Renaming %s to %s and %s to %s instead",
 795                ren1->pair->one->path, new_path1,
 796                ren2->pair->one->path, new_path2);
 797         remove_file(o, 0, ren1->pair->two->path, 0);
 798         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 799         update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 800         free(new_path2);
 801         free(new_path1);
 802 }
 803
 804 static int process_renames(struct merge_options *o,
 805                            struct string_list *a_renames,
 806                            struct string_list *b_renames)
 807 {
 808         int clean_merge = 1, i, j;
 809         struct string_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
 810         const struct rename *sre;
 811
 812         for (i = 0; i < a_renames->nr; i++) {
 813                 sre = a_renames->items[i].util;
 814                 string_list_insert(sre->pair->two->path, &a_by_dst)->util
 815                         = sre->dst_entry;
 816         }
 817         for (i = 0; i < b_renames->nr; i++) {
 818                 sre = b_renames->items[i].util;
 819                 string_list_insert(sre->pair->two->path, &b_by_dst)->util
 820                         = sre->dst_entry;
 821         }
 822
 823         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 824                 char *src;
 825                 struct string_list *renames1, *renames2Dst;
 826                 struct rename *ren1 = NULL, *ren2 = NULL;
 827                 const char *branch1, *branch2;
 828                 const char *ren1_src, *ren1_dst;
 829
 830                 if (i >= a_renames->nr) {
 831                         ren2 = b_renames->items[j++].util;
 832                 } else if (j >= b_renames->nr) {
 833                         ren1 = a_renames->items[i++].util;
 834                 } else {
 835                         int compare = strcmp(a_renames->items[i].string,
 836                                              b_renames->items[j].string);
 837                         if (compare <= 0)
 838                                 ren1 = a_renames->items[i++].util;
 839                         if (compare >= 0)
 840                                 ren2 = b_renames->items[j++].util;
 841                 }
 842
 843                 /* TODO: refactor, so that 1/2 are not needed */
 844                 if (ren1) {
 845                         renames1 = a_renames;
 846                         renames2Dst = &b_by_dst;
 847                         branch1 = o->branch1;
 848                         branch2 = o->branch2;
 849                 } else {
 850                         struct rename *tmp;
 851                         renames1 = b_renames;
 852                         renames2Dst = &a_by_dst;
 853                         branch1 = o->branch2;
 854                         branch2 = o->branch1;
 855                         tmp = ren2;
 856                         ren2 = ren1;
 857                         ren1 = tmp;
 858                 }
 859                 src = ren1->pair->one->path;
 860
 861                 ren1->dst_entry->processed = 1;
 862                 ren1->src_entry->processed = 1;
 863
 864                 if (ren1->processed)
 865                         continue;
 866                 ren1->processed = 1;
 867
 868                 ren1_src = ren1->pair->one->path;
 869                 ren1_dst = ren1->pair->two->path;
 870
 871                 if (ren2) {
 872                         const char *ren2_src = ren2->pair->one->path;
 873                         const char *ren2_dst = ren2->pair->two->path;
 874                         /* Renamed in 1 and renamed in 2 */
 875                         if (strcmp(ren1_src, ren2_src) != 0)
 876                                 die("ren1.src != ren2.src");
 877                         ren2->dst_entry->processed = 1;
 878                         ren2->processed = 1;
 879                         if (strcmp(ren1_dst, ren2_dst) != 0) {
 880                                 clean_merge = 0;
 881                                 output(o, 1, "CONFLICT (rename/rename): "
 882                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
 883                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
 884                                        src, ren1_dst, branch1,
 885                                        src, ren2_dst, branch2,
 886                                        o->call_depth ? " (left unresolved)": "");
 887                                 if (o->call_depth) {
 888                                         remove_file_from_cache(src);
 889                                         update_file(o, 0, ren1->pair->one->sha1,
 890                                                     ren1->pair->one->mode, src);
 891                                 }
 892                                 conflict_rename_rename(o, ren1, branch1, ren2, branch2);
 893                         } else {
 894                                 struct merge_file_info mfi;
 895                                 remove_file(o, 1, ren1_src, 1);
 896                                 mfi = merge_file(o,
 897                                                  ren1->pair->one,
 898                                                  ren1->pair->two,
 899                                                  ren2->pair->two,
 900                                                  branch1,
 901                                                  branch2);
 902                                 if (mfi.merge || !mfi.clean)
 903                                         output(o, 1, "Renaming %s->%s", src, ren1_dst);
 904
 905                                 if (mfi.merge)
 906                                         output(o, 2, "Auto-merging %s", ren1_dst);
 907
 908                                 if (!mfi.clean) {
 909                                         output(o, 1, "CONFLICT (content): merge conflict in %s",
 910                                                ren1_dst);
 911                                         clean_merge = 0;
 912
 913                                         if (!o->call_depth)
 914                                                 update_stages(ren1_dst,
 915                                                               ren1->pair->one,
 916                                                               ren1->pair->two,
 917                                                               ren2->pair->two,
 918                                                               1 /* clear */);
 919                                 }
 920                                 update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 921                         }
 922                 } else {
 923                         /* Renamed in 1, maybe changed in 2 */
 924                         struct string_list_item *item;
 925                         /* we only use sha1 and mode of these */
 926                         struct diff_filespec src_other, dst_other;
 927                         int try_merge, stage = a_renames == renames1 ? 3: 2;
 928
 929                         remove_file(o, 1, ren1_src, o->call_depth || stage == 3);
 930
 931                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
 932                         src_other.mode = ren1->src_entry->stages[stage].mode;
 933                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
 934                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
 935
 936                         try_merge = 0;
 937
 938                         if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
 939                                 clean_merge = 0;
 940                                 output(o, 1, "CONFLICT (rename/directory): Rename %s->%s in %s "
 941                                        " directory %s added in %s",
 942                                        ren1_src, ren1_dst, branch1,
 943                                        ren1_dst, branch2);
 944                                 conflict_rename_dir(o, ren1, branch1);
 945                         } else if (sha_eq(src_other.sha1, null_sha1)) {
 946                                 clean_merge = 0;
 947                                 output(o, 1, "CONFLICT (rename/delete): Rename %s->%s in %s "
 948                                        "and deleted in %s",
 949                                        ren1_src, ren1_dst, branch1,
 950                                        branch2);
 951                                 update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
 952                                 if (!o->call_depth)
 953                                         update_stages(ren1_dst, NULL,
 954                                                         branch1 == o->branch1 ?
 955                                                         ren1->pair->two : NULL,
 956                                                         branch1 == o->branch1 ?
 957                                                         NULL : ren1->pair->two, 1);
 958                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
 959                                 const char *new_path;
 960                                 clean_merge = 0;
 961                                 try_merge = 1;
 962                                 output(o, 1, "CONFLICT (rename/add): Rename %s->%s in %s. "
 963                                        "%s added in %s",
 964                                        ren1_src, ren1_dst, branch1,
 965                                        ren1_dst, branch2);
 966                                 if (o->call_depth) {
 967                                         struct merge_file_info mfi;
 968                                         struct diff_filespec one, a, b;
 969
 970                                         one.path = a.path = b.path =
 971                                                 (char *)ren1_dst;
 972                                         hashcpy(one.sha1, null_sha1);
 973                                         one.mode = 0;
 974                                         hashcpy(a.sha1, ren1->pair->two->sha1);
 975                                         a.mode = ren1->pair->two->mode;
 976                                         hashcpy(b.sha1, dst_other.sha1);
 977                                         b.mode = dst_other.mode;
 978                                         mfi = merge_file(o, &one, &a, &b,
 979                                                          branch1,
 980                                                          branch2);
 981                                         output(o, 1, "Adding merged %s", ren1_dst);
 982                                         update_file(o, 0,
 983                                                     mfi.sha,
 984                                                     mfi.mode,
 985                                                     ren1_dst);
 986                                 } else {
 987                                         new_path = unique_path(o, ren1_dst, branch2);
 988                                         output(o, 1, "Adding as %s instead", new_path);
 989                                         update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
 990                                 }
 991                         } else if ((item = string_list_lookup(ren1_dst, renames2Dst))) {
 992                                 ren2 = item->util;
 993                                 clean_merge = 0;
 994                                 ren2->processed = 1;
 995                                 output(o, 1, "CONFLICT (rename/rename): "
 996                                        "Rename %s->%s in %s. "
 997                                        "Rename %s->%s in %s",
 998                                        ren1_src, ren1_dst, branch1,
 999                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
1000                                 conflict_rename_rename_2(o, ren1, branch1, ren2, branch2);
1001                         } else
1002                                 try_merge = 1;
1003
1004                         if (try_merge) {
1005                                 struct diff_filespec *one, *a, *b;
1006                                 struct merge_file_info mfi;
1007                                 src_other.path = (char *)ren1_src;
1008
1009                                 one = ren1->pair->one;
1010                                 if (a_renames == renames1) {
1011                                         a = ren1->pair->two;
1012                                         b = &src_other;
1013                                 } else {
1014                                         b = ren1->pair->two;
1015                                         a = &src_other;
1016                                 }
1017                                 mfi = merge_file(o, one, a, b,
1018                                                 o->branch1, o->branch2);
1019
1020                                 if (mfi.clean &&
1021                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
1022                                     mfi.mode == ren1->pair->two->mode)
1023                                         /*
1024                                          * This messaged is part of
1025                                          * t6022 test. If you change
1026                                          * it update the test too.
1027                                          */
1028                                         output(o, 3, "Skipped %s (merged same as existing)", ren1_dst);
1029                                 else {
1030                                         if (mfi.merge || !mfi.clean)
1031                                                 output(o, 1, "Renaming %s => %s", ren1_src, ren1_dst);
1032                                         if (mfi.merge)
1033                                                 output(o, 2, "Auto-merging %s", ren1_dst);
1034                                         if (!mfi.clean) {
1035                                                 output(o, 1, "CONFLICT (rename/modify): Merge conflict in %s",
1036                                                        ren1_dst);
1037                                                 clean_merge = 0;
1038
1039                                                 if (!o->call_depth)
1040                                                         update_stages(ren1_dst,
1041                                                                       one, a, b, 1);
1042                                         }
1043                                         update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1044                                 }
1045                         }
1046                 }
1047         }
1048         string_list_clear(&a_by_dst, 0);
1049         string_list_clear(&b_by_dst, 0);
1050
1051         return clean_merge;
1052 }
1053
1054 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1055 {
1056         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1057 }
1058
1059 /* Per entry merge function */
1060 static int process_entry(struct merge_options *o,
1061                          const char *path, struct stage_data *entry)
1062 {
1063         /*
1064         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1065         print_index_entry("\tpath: ", entry);
1066         */
1067         int clean_merge = 1;
1068         unsigned o_mode = entry->stages[1].mode;
1069         unsigned a_mode = entry->stages[2].mode;
1070         unsigned b_mode = entry->stages[3].mode;
1071         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1072         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1073         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1074
1075         if (o_sha && (!a_sha || !b_sha)) {
1076                 /* Case A: Deleted in one */
1077                 if ((!a_sha && !b_sha) ||
1078                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1079                     (!a_sha && sha_eq(b_sha, o_sha))) {
1080                         /* Deleted in both or deleted in one and
1081                          * unchanged in the other */
1082                         if (a_sha)
1083                                 output(o, 2, "Removing %s", path);
1084                         /* do not touch working file if it did not exist */
1085                         remove_file(o, 1, path, !a_sha);
1086                 } else {
1087                         /* Deleted in one and changed in the other */
1088                         clean_merge = 0;
1089                         if (!a_sha) {
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->branch1,
1093                                        o->branch2, o->branch2, path);
1094                                 update_file(o, 0, b_sha, b_mode, path);
1095                         } else {
1096                                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1097                                        "and modified in %s. Version %s of %s left in tree.",
1098                                        path, o->branch2,
1099                                        o->branch1, o->branch1, path);
1100                                 update_file(o, 0, a_sha, a_mode, path);
1101                         }
1102                 }
1103
1104         } else if ((!o_sha && a_sha && !b_sha) ||
1105                    (!o_sha && !a_sha && b_sha)) {
1106                 /* Case B: Added in one. */
1107                 const char *add_branch;
1108                 const char *other_branch;
1109                 unsigned mode;
1110                 const unsigned char *sha;
1111                 const char *conf;
1112
1113                 if (a_sha) {
1114                         add_branch = o->branch1;
1115                         other_branch = o->branch2;
1116                         mode = a_mode;
1117                         sha = a_sha;
1118                         conf = "file/directory";
1119                 } else {
1120                         add_branch = o->branch2;
1121                         other_branch = o->branch1;
1122                         mode = b_mode;
1123                         sha = b_sha;
1124                         conf = "directory/file";
1125                 }
1126                 if (string_list_has_string(&o->current_directory_set, path)) {
1127                         const char *new_path = unique_path(o, path, add_branch);
1128                         clean_merge = 0;
1129                         output(o, 1, "CONFLICT (%s): There is a directory with name %s in %s. "
1130                                "Adding %s as %s",
1131                                conf, path, other_branch, path, new_path);
1132                         remove_file(o, 0, path, 0);
1133                         update_file(o, 0, sha, mode, new_path);
1134                 } else {
1135                         output(o, 2, "Adding %s", path);
1136                         update_file(o, 1, sha, mode, path);
1137                 }
1138         } else if (a_sha && b_sha) {
1139                 /* Case C: Added in both (check for same permissions) and */
1140                 /* case D: Modified in both, but differently. */
1141                 const char *reason = "content";
1142                 struct merge_file_info mfi;
1143                 struct diff_filespec one, a, b;
1144
1145                 if (!o_sha) {
1146                         reason = "add/add";
1147                         o_sha = (unsigned char *)null_sha1;
1148                 }
1149                 output(o, 2, "Auto-merging %s", path);
1150                 one.path = a.path = b.path = (char *)path;
1151                 hashcpy(one.sha1, o_sha);
1152                 one.mode = o_mode;
1153                 hashcpy(a.sha1, a_sha);
1154                 a.mode = a_mode;
1155                 hashcpy(b.sha1, b_sha);
1156                 b.mode = b_mode;
1157
1158                 mfi = merge_file(o, &one, &a, &b,
1159                                  o->branch1, o->branch2);
1160
1161                 clean_merge = mfi.clean;
1162                 if (!mfi.clean) {
1163                         if (S_ISGITLINK(mfi.mode))
1164                                 reason = "submodule";
1165                         output(o, 1, "CONFLICT (%s): Merge conflict in %s",
1166                                         reason, path);
1167                 }
1168                 update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
1169         } else if (!o_sha && !a_sha && !b_sha) {
1170                 /*
1171                  * this entry was deleted altogether. a_mode == 0 means
1172                  * we had that path and want to actively remove it.
1173                  */
1174                 remove_file(o, 1, path, !a_mode);
1175         } else
1176                 die("Fatal merge failure, shouldn't happen.");
1177
1178         return clean_merge;
1179 }
1180
1181 struct unpack_trees_error_msgs get_porcelain_error_msgs(void)
1182 {
1183         struct unpack_trees_error_msgs msgs = {
1184                 /* would_overwrite */
1185                 "Your local changes to '%s' would be overwritten by merge.  Aborting.",
1186                 /* not_uptodate_file */
1187                 "Your local changes to '%s' would be overwritten by merge.  Aborting.",
1188                 /* not_uptodate_dir */
1189                 "Updating '%s' would lose untracked files in it.  Aborting.",
1190                 /* would_lose_untracked */
1191                 "Untracked working tree file '%s' would be %s by merge.  Aborting",
1192                 /* bind_overlap -- will not happen here */
1193                 NULL,
1194         };
1195         if (advice_commit_before_merge) {
1196                 msgs.would_overwrite = msgs.not_uptodate_file =
1197                         "Your local changes to '%s' would be overwritten by merge.  Aborting.\n"
1198                         "Please, commit your changes or stash them before you can merge.";
1199         }
1200         return msgs;
1201 }
1202
1203 int merge_trees(struct merge_options *o,
1204                 struct tree *head,
1205                 struct tree *merge,
1206                 struct tree *common,
1207                 struct tree **result)
1208 {
1209         int code, clean;
1210
1211         if (o->subtree_shift) {
1212                 merge = shift_tree_object(head, merge, o->subtree_shift);
1213                 common = shift_tree_object(head, common, o->subtree_shift);
1214         }
1215
1216         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1217                 output(o, 0, "Already uptodate!");
1218                 *result = head;
1219                 return 1;
1220         }
1221
1222         code = git_merge_trees(o->call_depth, common, head, merge);
1223
1224         if (code != 0) {
1225                 if (show(o, 4) || o->call_depth)
1226                         die("merging of trees %s and %s failed",
1227                             sha1_to_hex(head->object.sha1),
1228                             sha1_to_hex(merge->object.sha1));
1229                 else
1230                         exit(128);
1231         }
1232
1233         if (unmerged_cache()) {
1234                 struct string_list *entries, *re_head, *re_merge;
1235                 int i;
1236                 string_list_clear(&o->current_file_set, 1);
1237                 string_list_clear(&o->current_directory_set, 1);
1238                 get_files_dirs(o, head);
1239                 get_files_dirs(o, merge);
1240
1241                 entries = get_unmerged();
1242                 re_head  = get_renames(o, head, common, head, merge, entries);
1243                 re_merge = get_renames(o, merge, common, head, merge, entries);
1244                 clean = process_renames(o, re_head, re_merge);
1245                 for (i = 0; i < entries->nr; i++) {
1246                         const char *path = entries->items[i].string;
1247                         struct stage_data *e = entries->items[i].util;
1248                         if (!e->processed
1249                                 && !process_entry(o, path, e))
1250                                 clean = 0;
1251                 }
1252
1253                 string_list_clear(re_merge, 0);
1254                 string_list_clear(re_head, 0);
1255                 string_list_clear(entries, 1);
1256
1257         }
1258         else
1259                 clean = 1;
1260
1261         if (o->call_depth)
1262                 *result = write_tree_from_memory(o);
1263
1264         return clean;
1265 }
1266
1267 static struct commit_list *reverse_commit_list(struct commit_list *list)
1268 {
1269         struct commit_list *next = NULL, *current, *backup;
1270         for (current = list; current; current = backup) {
1271                 backup = current->next;
1272                 current->next = next;
1273                 next = current;
1274         }
1275         return next;
1276 }
1277
1278 /*
1279  * Merge the commits h1 and h2, return the resulting virtual
1280  * commit object and a flag indicating the cleanness of the merge.
1281  */
1282 int merge_recursive(struct merge_options *o,
1283                     struct commit *h1,
1284                     struct commit *h2,
1285                     struct commit_list *ca,
1286                     struct commit **result)
1287 {
1288         struct commit_list *iter;
1289         struct commit *merged_common_ancestors;
1290         struct tree *mrtree = mrtree;
1291         int clean;
1292
1293         if (show(o, 4)) {
1294                 output(o, 4, "Merging:");
1295                 output_commit_title(o, h1);
1296                 output_commit_title(o, h2);
1297         }
1298
1299         if (!ca) {
1300                 ca = get_merge_bases(h1, h2, 1);
1301                 ca = reverse_commit_list(ca);
1302         }
1303
1304         if (show(o, 5)) {
1305                 output(o, 5, "found %u common ancestor(s):", commit_list_count(ca));
1306                 for (iter = ca; iter; iter = iter->next)
1307                         output_commit_title(o, iter->item);
1308         }
1309
1310         merged_common_ancestors = pop_commit(&ca);
1311         if (merged_common_ancestors == NULL) {
1312                 /* if there is no common ancestor, make an empty tree */
1313                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1314
1315                 tree->object.parsed = 1;
1316                 tree->object.type = OBJ_TREE;
1317                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1318                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1319         }
1320
1321         for (iter = ca; iter; iter = iter->next) {
1322                 const char *saved_b1, *saved_b2;
1323                 o->call_depth++;
1324                 /*
1325                  * When the merge fails, the result contains files
1326                  * with conflict markers. The cleanness flag is
1327                  * ignored, it was never actually used, as result of
1328                  * merge_trees has always overwritten it: the committed
1329                  * "conflicts" were already resolved.
1330                  */
1331                 discard_cache();
1332                 saved_b1 = o->branch1;
1333                 saved_b2 = o->branch2;
1334                 o->branch1 = "Temporary merge branch 1";
1335                 o->branch2 = "Temporary merge branch 2";
1336                 merge_recursive(o, merged_common_ancestors, iter->item,
1337                                 NULL, &merged_common_ancestors);
1338                 o->branch1 = saved_b1;
1339                 o->branch2 = saved_b2;
1340                 o->call_depth--;
1341
1342                 if (!merged_common_ancestors)
1343                         die("merge returned no commit");
1344         }
1345
1346         discard_cache();
1347         if (!o->call_depth)
1348                 read_cache();
1349
1350         o->ancestor = "merged common ancestors";
1351         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
1352                             &mrtree);
1353
1354         if (o->call_depth) {
1355                 *result = make_virtual_commit(mrtree, "merged tree");
1356                 commit_list_insert(h1, &(*result)->parents);
1357                 commit_list_insert(h2, &(*result)->parents->next);
1358         }
1359         flush_output(o);
1360         return clean;
1361 }
1362
1363 static struct commit *get_ref(const unsigned char *sha1, const char *name)
1364 {
1365         struct object *object;
1366
1367         object = deref_tag(parse_object(sha1), name, strlen(name));
1368         if (!object)
1369                 return NULL;
1370         if (object->type == OBJ_TREE)
1371                 return make_virtual_commit((struct tree*)object, name);
1372         if (object->type != OBJ_COMMIT)
1373                 return NULL;
1374         if (parse_commit((struct commit *)object))
1375                 return NULL;
1376         return (struct commit *)object;
1377 }
1378
1379 int merge_recursive_generic(struct merge_options *o,
1380                             const unsigned char *head,
1381                             const unsigned char *merge,
1382                             int num_base_list,
1383                             const unsigned char **base_list,
1384                             struct commit **result)
1385 {
1386         int clean, index_fd;
1387         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1388         struct commit *head_commit = get_ref(head, o->branch1);
1389         struct commit *next_commit = get_ref(merge, o->branch2);
1390         struct commit_list *ca = NULL;
1391
1392         if (base_list) {
1393                 int i;
1394                 for (i = 0; i < num_base_list; ++i) {
1395                         struct commit *base;
1396                         if (!(base = get_ref(base_list[i], sha1_to_hex(base_list[i]))))
1397                                 return error("Could not parse object '%s'",
1398                                         sha1_to_hex(base_list[i]));
1399                         commit_list_insert(base, &ca);
1400                 }
1401         }
1402
1403         index_fd = hold_locked_index(lock, 1);
1404         clean = merge_recursive(o, head_commit, next_commit, ca,
1405                         result);
1406         if (active_cache_changed &&
1407                         (write_cache(index_fd, active_cache, active_nr) ||
1408                          commit_locked_index(lock)))
1409                 return error("Unable to write index.");
1410
1411         return clean ? 0 : 1;
1412 }
1413
1414 static int merge_recursive_config(const char *var, const char *value, void *cb)
1415 {
1416         struct merge_options *o = cb;
1417         if (!strcasecmp(var, "merge.verbosity")) {
1418                 o->verbosity = git_config_int(var, value);
1419                 return 0;
1420         }
1421         if (!strcasecmp(var, "diff.renamelimit")) {
1422                 o->diff_rename_limit = git_config_int(var, value);
1423                 return 0;
1424         }
1425         if (!strcasecmp(var, "merge.renamelimit")) {
1426                 o->merge_rename_limit = git_config_int(var, value);
1427                 return 0;
1428         }
1429         return git_xmerge_config(var, value, cb);
1430 }
1431
1432 void init_merge_options(struct merge_options *o)
1433 {
1434         memset(o, 0, sizeof(struct merge_options));
1435         o->verbosity = 2;
1436         o->buffer_output = 1;
1437         o->diff_rename_limit = -1;
1438         o->merge_rename_limit = -1;
1439         git_config(merge_recursive_config, o);
1440         if (getenv("GIT_MERGE_VERBOSITY"))
1441                 o->verbosity =
1442                         strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1443         if (o->verbosity >= 5)
1444                 o->buffer_output = 0;
1445         strbuf_init(&o->obuf, 0);
1446         memset(&o->current_file_set, 0, sizeof(struct string_list));
1447         o->current_file_set.strdup_strings = 1;
1448         memset(&o->current_directory_set, 0, sizeof(struct string_list));
1449         o->current_directory_set.strdup_strings = 1;
1450 }