merge-recursive.c

   1 /*
   2  * Recursive Merge algorithm stolen from git-merge-recursive.py by
   3  * Fredrik Kuivinen.
   4  * The thieves were Alex Riesen and Johannes Schindelin, in June/July 2006
   5  */
   6 #include "cache.h"
   7 #include "cache-tree.h"
   8 #include "commit.h"
   9 #include "blob.h"
  10 #include "builtin.h"
  11 #include "tree-walk.h"
  12 #include "diff.h"
  13 #include "diffcore.h"
  14 #include "tag.h"
  15 #include "unpack-trees.h"
  16 #include "string-list.h"
  17 #include "xdiff-interface.h"
  18 #include "ll-merge.h"
  19 #include "attr.h"
  20 #include "merge-recursive.h"
  21 #include "dir.h"
  22
  23 static struct tree *shift_tree_object(struct tree *one, struct tree *two)
  24 {
  25         unsigned char shifted[20];
  26
  27         /*
  28          * NEEDSWORK: this limits the recursion depth to hardcoded
  29          * value '2' to avoid excessive overhead.
  30          */
  31         shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
  32         if (!hashcmp(two->object.sha1, shifted))
  33                 return two;
  34         return lookup_tree(shifted);
  35 }
  36
  37 /*
  38  * A virtual commit has (const char *)commit->util set to the name.
  39  */
  40
  41 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  42 {
  43         struct commit *commit = xcalloc(1, sizeof(struct commit));
  44         commit->tree = tree;
  45         commit->util = (void*)comment;
  46         /* avoid warnings */
  47         commit->object.parsed = 1;
  48         return commit;
  49 }
  50
  51 /*
  52  * Since we use get_tree_entry(), which does not put the read object into
  53  * the object pool, we cannot rely on a == b.
  54  */
  55 static int sha_eq(const unsigned char *a, const unsigned char *b)
  56 {
  57         if (!a && !b)
  58                 return 2;
  59         return a && b && hashcmp(a, b) == 0;
  60 }
  61
  62 /*
  63  * Since we want to write the index eventually, we cannot reuse the index
  64  * for these (temporary) data.
  65  */
  66 struct stage_data
  67 {
  68         struct
  69         {
  70                 unsigned mode;
  71                 unsigned char sha[20];
  72         } stages[4];
  73         unsigned processed:1;
  74 };
  75
  76 static int show(struct merge_options *o, int v)
  77 {
  78         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
  79 }
  80
  81 static void flush_output(struct merge_options *o)
  82 {
  83         if (o->obuf.len) {
  84                 fputs(o->obuf.buf, stdout);
  85                 strbuf_reset(&o->obuf);
  86         }
  87 }
  88
  89 static void output(struct merge_options *o, int v, const char *fmt, ...)
  90 {
  91         int len;
  92         va_list ap;
  93
  94         if (!show(o, v))
  95                 return;
  96
  97         strbuf_grow(&o->obuf, o->call_depth * 2 + 2);
  98         memset(o->obuf.buf + o->obuf.len, ' ', o->call_depth * 2);
  99         strbuf_setlen(&o->obuf, o->obuf.len + o->call_depth * 2);
 100
 101         va_start(ap, fmt);
 102         len = vsnprintf(o->obuf.buf + o->obuf.len, strbuf_avail(&o->obuf), fmt, ap);
 103         va_end(ap);
 104
 105         if (len < 0)
 106                 len = 0;
 107         if (len >= strbuf_avail(&o->obuf)) {
 108                 strbuf_grow(&o->obuf, len + 2);
 109                 va_start(ap, fmt);
 110                 len = vsnprintf(o->obuf.buf + o->obuf.len, strbuf_avail(&o->obuf), fmt, ap);
 111                 va_end(ap);
 112                 if (len >= strbuf_avail(&o->obuf)) {
 113                         die("this should not happen, your snprintf is broken");
 114                 }
 115         }
 116         strbuf_setlen(&o->obuf, o->obuf.len + len);
 117         strbuf_add(&o->obuf, "\n", 1);
 118         if (!o->buffer_output)
 119                 flush_output(o);
 120 }
 121
 122 static void output_commit_title(struct merge_options *o, struct commit *commit)
 123 {
 124         int i;
 125         flush_output(o);
 126         for (i = o->call_depth; i--;)
 127                 fputs("  ", stdout);
 128         if (commit->util)
 129                 printf("virtual %s\n", (char *)commit->util);
 130         else {
 131                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 132                 if (parse_commit(commit) != 0)
 133                         printf("(bad commit)\n");
 134                 else {
 135                         const char *s;
 136                         int len;
 137                         for (s = commit->buffer; *s; s++)
 138                                 if (*s == '\n' && s[1] == '\n') {
 139                                         s += 2;
 140                                         break;
 141                                 }
 142                         for (len = 0; s[len] && '\n' != s[len]; len++)
 143                                 ; /* do nothing */
 144                         printf("%.*s\n", len, s);
 145                 }
 146         }
 147 }
 148
 149 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 150                 const char *path, int stage, int refresh, int options)
 151 {
 152         struct cache_entry *ce;
 153         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 154         if (!ce)
 155                 return error("addinfo_cache failed for path '%s'", path);
 156         return add_cache_entry(ce, options);
 157 }
 158
 159 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 160 {
 161         parse_tree(tree);
 162         init_tree_desc(desc, tree->buffer, tree->size);
 163 }
 164
 165 static int git_merge_trees(int index_only,
 166                            struct tree *common,
 167                            struct tree *head,
 168                            struct tree *merge)
 169 {
 170         int rc;
 171         struct tree_desc t[3];
 172         struct unpack_trees_options opts;
 173
 174         memset(&opts, 0, sizeof(opts));
 175         if (index_only)
 176                 opts.index_only = 1;
 177         else
 178                 opts.update = 1;
 179         opts.merge = 1;
 180         opts.head_idx = 2;
 181         opts.fn = threeway_merge;
 182         opts.src_index = &the_index;
 183         opts.dst_index = &the_index;
 184
 185         init_tree_desc_from_tree(t+0, common);
 186         init_tree_desc_from_tree(t+1, head);
 187         init_tree_desc_from_tree(t+2, merge);
 188
 189         rc = unpack_trees(3, t, &opts);
 190         cache_tree_free(&active_cache_tree);
 191         return rc;
 192 }
 193
 194 struct tree *write_tree_from_memory(struct merge_options *o)
 195 {
 196         struct tree *result = NULL;
 197
 198         if (unmerged_cache()) {
 199                 int i;
 200                 output(o, 0, "There are unmerged index entries:");
 201                 for (i = 0; i < active_nr; i++) {
 202                         struct cache_entry *ce = active_cache[i];
 203                         if (ce_stage(ce))
 204                                 output(o, 0, "%d %.*s", ce_stage(ce), ce_namelen(ce), ce->name);
 205                 }
 206                 return NULL;
 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(newpath, &o->current_directory_set);
 236         else
 237                 string_list_insert(newpath, &o->current_file_set);
 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(path, entries);
 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(ce->name, unmerged);
 292                 if (!item) {
 293                         item = string_list_insert(ce->name, unmerged);
 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(re->pair->one->path, entries);
 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(re->pair->two->path, entries);
 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(pair->one->path, renames);
 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) && errno != ENOENT)
 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(newpath, &o->current_file_set);
 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 void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 597 {
 598         unsigned long size;
 599         enum object_type type;
 600
 601         if (!hashcmp(sha1, null_sha1)) {
 602                 mm->ptr = xstrdup("");
 603                 mm->size = 0;
 604                 return;
 605         }
 606
 607         mm->ptr = read_sha1_file(sha1, &type, &size);
 608         if (!mm->ptr || type != OBJ_BLOB)
 609                 die("unable to read blob object %s", sha1_to_hex(sha1));
 610         mm->size = size;
 611 }
 612
 613 static int merge_3way(struct merge_options *o,
 614                       mmbuffer_t *result_buf,
 615                       struct diff_filespec *one,
 616                       struct diff_filespec *a,
 617                       struct diff_filespec *b,
 618                       const char *branch1,
 619                       const char *branch2)
 620 {
 621         mmfile_t orig, src1, src2;
 622         char *name1, *name2;
 623         int merge_status;
 624
 625         if (strcmp(a->path, b->path)) {
 626                 name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 627                 name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 628         } else {
 629                 name1 = xstrdup(mkpath("%s", branch1));
 630                 name2 = xstrdup(mkpath("%s", branch2));
 631         }
 632
 633         fill_mm(one->sha1, &orig);
 634         fill_mm(a->sha1, &src1);
 635         fill_mm(b->sha1, &src2);
 636
 637         merge_status = ll_merge(result_buf, a->path, &orig,
 638                                 &src1, name1, &src2, name2,
 639                                 o->call_depth);
 640
 641         free(name1);
 642         free(name2);
 643         free(orig.ptr);
 644         free(src1.ptr);
 645         free(src2.ptr);
 646         return merge_status;
 647 }
 648
 649 static struct merge_file_info merge_file(struct merge_options *o,
 650                                          struct diff_filespec *one,
 651                                          struct diff_filespec *a,
 652                                          struct diff_filespec *b,
 653                                          const char *branch1,
 654                                          const char *branch2)
 655 {
 656         struct merge_file_info result;
 657         result.merge = 0;
 658         result.clean = 1;
 659
 660         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 661                 result.clean = 0;
 662                 if (S_ISREG(a->mode)) {
 663                         result.mode = a->mode;
 664                         hashcpy(result.sha, a->sha1);
 665                 } else {
 666                         result.mode = b->mode;
 667                         hashcpy(result.sha, b->sha1);
 668                 }
 669         } else {
 670                 if (!sha_eq(a->sha1, one->sha1) && !sha_eq(b->sha1, one->sha1))
 671                         result.merge = 1;
 672
 673                 /*
 674                  * Merge modes
 675                  */
 676                 if (a->mode == b->mode || a->mode == one->mode)
 677                         result.mode = b->mode;
 678                 else {
 679                         result.mode = a->mode;
 680                         if (b->mode != one->mode) {
 681                                 result.clean = 0;
 682                                 result.merge = 1;
 683                         }
 684                 }
 685
 686                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, one->sha1))
 687                         hashcpy(result.sha, b->sha1);
 688                 else if (sha_eq(b->sha1, one->sha1))
 689                         hashcpy(result.sha, a->sha1);
 690                 else if (S_ISREG(a->mode)) {
 691                         mmbuffer_t result_buf;
 692                         int merge_status;
 693
 694                         merge_status = merge_3way(o, &result_buf, one, a, b,
 695                                                   branch1, branch2);
 696
 697                         if ((merge_status < 0) || !result_buf.ptr)
 698                                 die("Failed to execute internal merge");
 699
 700                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 701                                             blob_type, result.sha))
 702                                 die("Unable to add %s to database",
 703                                     a->path);
 704
 705                         free(result_buf.ptr);
 706                         result.clean = (merge_status == 0);
 707                 } else if (S_ISGITLINK(a->mode)) {
 708                         result.clean = 0;
 709                         hashcpy(result.sha, a->sha1);
 710                 } else if (S_ISLNK(a->mode)) {
 711                         hashcpy(result.sha, a->sha1);
 712
 713                         if (!sha_eq(a->sha1, b->sha1))
 714                                 result.clean = 0;
 715                 } else {
 716                         die("unsupported object type in the tree");
 717                 }
 718         }
 719
 720         return result;
 721 }
 722
 723 static void conflict_rename_rename(struct merge_options *o,
 724                                    struct rename *ren1,
 725                                    const char *branch1,
 726                                    struct rename *ren2,
 727                                    const char *branch2)
 728 {
 729         char *del[2];
 730         int delp = 0;
 731         const char *ren1_dst = ren1->pair->two->path;
 732         const char *ren2_dst = ren2->pair->two->path;
 733         const char *dst_name1 = ren1_dst;
 734         const char *dst_name2 = ren2_dst;
 735         if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
 736                 dst_name1 = del[delp++] = unique_path(o, ren1_dst, branch1);
 737                 output(o, 1, "%s is a directory in %s adding as %s instead",
 738                        ren1_dst, branch2, dst_name1);
 739                 remove_file(o, 0, ren1_dst, 0);
 740         }
 741         if (string_list_has_string(&o->current_directory_set, ren2_dst)) {
 742                 dst_name2 = del[delp++] = unique_path(o, ren2_dst, branch2);
 743                 output(o, 1, "%s is a directory in %s adding as %s instead",
 744                        ren2_dst, branch1, dst_name2);
 745                 remove_file(o, 0, ren2_dst, 0);
 746         }
 747         if (o->call_depth) {
 748                 remove_file_from_cache(dst_name1);
 749                 remove_file_from_cache(dst_name2);
 750                 /*
 751                  * Uncomment to leave the conflicting names in the resulting tree
 752                  *
 753                  * update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
 754                  * update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
 755                  */
 756         } else {
 757                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
 758                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
 759         }
 760         while (delp--)
 761                 free(del[delp]);
 762 }
 763
 764 static void conflict_rename_dir(struct merge_options *o,
 765                                 struct rename *ren1,
 766                                 const char *branch1)
 767 {
 768         char *new_path = unique_path(o, ren1->pair->two->path, branch1);
 769         output(o, 1, "Renaming %s to %s instead", ren1->pair->one->path, new_path);
 770         remove_file(o, 0, ren1->pair->two->path, 0);
 771         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
 772         free(new_path);
 773 }
 774
 775 static void conflict_rename_rename_2(struct merge_options *o,
 776                                      struct rename *ren1,
 777                                      const char *branch1,
 778                                      struct rename *ren2,
 779                                      const char *branch2)
 780 {
 781         char *new_path1 = unique_path(o, ren1->pair->two->path, branch1);
 782         char *new_path2 = unique_path(o, ren2->pair->two->path, branch2);
 783         output(o, 1, "Renaming %s to %s and %s to %s instead",
 784                ren1->pair->one->path, new_path1,
 785                ren2->pair->one->path, new_path2);
 786         remove_file(o, 0, ren1->pair->two->path, 0);
 787         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 788         update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 789         free(new_path2);
 790         free(new_path1);
 791 }
 792
 793 static int process_renames(struct merge_options *o,
 794                            struct string_list *a_renames,
 795                            struct string_list *b_renames)
 796 {
 797         int clean_merge = 1, i, j;
 798         struct string_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
 799         const struct rename *sre;
 800
 801         for (i = 0; i < a_renames->nr; i++) {
 802                 sre = a_renames->items[i].util;
 803                 string_list_insert(sre->pair->two->path, &a_by_dst)->util
 804                         = sre->dst_entry;
 805         }
 806         for (i = 0; i < b_renames->nr; i++) {
 807                 sre = b_renames->items[i].util;
 808                 string_list_insert(sre->pair->two->path, &b_by_dst)->util
 809                         = sre->dst_entry;
 810         }
 811
 812         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 813                 char *src;
 814                 struct string_list *renames1, *renames2Dst;
 815                 struct rename *ren1 = NULL, *ren2 = NULL;
 816                 const char *branch1, *branch2;
 817                 const char *ren1_src, *ren1_dst;
 818
 819                 if (i >= a_renames->nr) {
 820                         ren2 = b_renames->items[j++].util;
 821                 } else if (j >= b_renames->nr) {
 822                         ren1 = a_renames->items[i++].util;
 823                 } else {
 824                         int compare = strcmp(a_renames->items[i].string,
 825                                              b_renames->items[j].string);
 826                         if (compare <= 0)
 827                                 ren1 = a_renames->items[i++].util;
 828                         if (compare >= 0)
 829                                 ren2 = b_renames->items[j++].util;
 830                 }
 831
 832                 /* TODO: refactor, so that 1/2 are not needed */
 833                 if (ren1) {
 834                         renames1 = a_renames;
 835                         renames2Dst = &b_by_dst;
 836                         branch1 = o->branch1;
 837                         branch2 = o->branch2;
 838                 } else {
 839                         struct rename *tmp;
 840                         renames1 = b_renames;
 841                         renames2Dst = &a_by_dst;
 842                         branch1 = o->branch2;
 843                         branch2 = o->branch1;
 844                         tmp = ren2;
 845                         ren2 = ren1;
 846                         ren1 = tmp;
 847                 }
 848                 src = ren1->pair->one->path;
 849
 850                 ren1->dst_entry->processed = 1;
 851                 ren1->src_entry->processed = 1;
 852
 853                 if (ren1->processed)
 854                         continue;
 855                 ren1->processed = 1;
 856
 857                 ren1_src = ren1->pair->one->path;
 858                 ren1_dst = ren1->pair->two->path;
 859
 860                 if (ren2) {
 861                         const char *ren2_src = ren2->pair->one->path;
 862                         const char *ren2_dst = ren2->pair->two->path;
 863                         /* Renamed in 1 and renamed in 2 */
 864                         if (strcmp(ren1_src, ren2_src) != 0)
 865                                 die("ren1.src != ren2.src");
 866                         ren2->dst_entry->processed = 1;
 867                         ren2->processed = 1;
 868                         if (strcmp(ren1_dst, ren2_dst) != 0) {
 869                                 clean_merge = 0;
 870                                 output(o, 1, "CONFLICT (rename/rename): "
 871                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
 872                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
 873                                        src, ren1_dst, branch1,
 874                                        src, ren2_dst, branch2,
 875                                        o->call_depth ? " (left unresolved)": "");
 876                                 if (o->call_depth) {
 877                                         remove_file_from_cache(src);
 878                                         update_file(o, 0, ren1->pair->one->sha1,
 879                                                     ren1->pair->one->mode, src);
 880                                 }
 881                                 conflict_rename_rename(o, ren1, branch1, ren2, branch2);
 882                         } else {
 883                                 struct merge_file_info mfi;
 884                                 remove_file(o, 1, ren1_src, 1);
 885                                 mfi = merge_file(o,
 886                                                  ren1->pair->one,
 887                                                  ren1->pair->two,
 888                                                  ren2->pair->two,
 889                                                  branch1,
 890                                                  branch2);
 891                                 if (mfi.merge || !mfi.clean)
 892                                         output(o, 1, "Renaming %s->%s", src, ren1_dst);
 893
 894                                 if (mfi.merge)
 895                                         output(o, 2, "Auto-merging %s", ren1_dst);
 896
 897                                 if (!mfi.clean) {
 898                                         output(o, 1, "CONFLICT (content): merge conflict in %s",
 899                                                ren1_dst);
 900                                         clean_merge = 0;
 901
 902                                         if (!o->call_depth)
 903                                                 update_stages(ren1_dst,
 904                                                               ren1->pair->one,
 905                                                               ren1->pair->two,
 906                                                               ren2->pair->two,
 907                                                               1 /* clear */);
 908                                 }
 909                                 update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 910                         }
 911                 } else {
 912                         /* Renamed in 1, maybe changed in 2 */
 913                         struct string_list_item *item;
 914                         /* we only use sha1 and mode of these */
 915                         struct diff_filespec src_other, dst_other;
 916                         int try_merge, stage = a_renames == renames1 ? 3: 2;
 917
 918                         remove_file(o, 1, ren1_src, o->call_depth || stage == 3);
 919
 920                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
 921                         src_other.mode = ren1->src_entry->stages[stage].mode;
 922                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
 923                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
 924
 925                         try_merge = 0;
 926
 927                         if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
 928                                 clean_merge = 0;
 929                                 output(o, 1, "CONFLICT (rename/directory): Rename %s->%s in %s "
 930                                        " directory %s added in %s",
 931                                        ren1_src, ren1_dst, branch1,
 932                                        ren1_dst, branch2);
 933                                 conflict_rename_dir(o, ren1, branch1);
 934                         } else if (sha_eq(src_other.sha1, null_sha1)) {
 935                                 clean_merge = 0;
 936                                 output(o, 1, "CONFLICT (rename/delete): Rename %s->%s in %s "
 937                                        "and deleted in %s",
 938                                        ren1_src, ren1_dst, branch1,
 939                                        branch2);
 940                                 update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
 941                                 if (!o->call_depth)
 942                                         update_stages(ren1_dst, NULL,
 943                                                         branch1 == o->branch1 ?
 944                                                         ren1->pair->two : NULL,
 945                                                         branch1 == o->branch1 ?
 946                                                         NULL : ren1->pair->two, 1);
 947                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
 948                                 const char *new_path;
 949                                 clean_merge = 0;
 950                                 try_merge = 1;
 951                                 output(o, 1, "CONFLICT (rename/add): Rename %s->%s in %s. "
 952                                        "%s added in %s",
 953                                        ren1_src, ren1_dst, branch1,
 954                                        ren1_dst, branch2);
 955                                 new_path = unique_path(o, ren1_dst, branch2);
 956                                 output(o, 1, "Adding as %s instead", new_path);
 957                                 update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
 958                         } else if ((item = string_list_lookup(ren1_dst, renames2Dst))) {
 959                                 ren2 = item->util;
 960                                 clean_merge = 0;
 961                                 ren2->processed = 1;
 962                                 output(o, 1, "CONFLICT (rename/rename): "
 963                                        "Rename %s->%s in %s. "
 964                                        "Rename %s->%s in %s",
 965                                        ren1_src, ren1_dst, branch1,
 966                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
 967                                 conflict_rename_rename_2(o, ren1, branch1, ren2, branch2);
 968                         } else
 969                                 try_merge = 1;
 970
 971                         if (try_merge) {
 972                                 struct diff_filespec *one, *a, *b;
 973                                 struct merge_file_info mfi;
 974                                 src_other.path = (char *)ren1_src;
 975
 976                                 one = ren1->pair->one;
 977                                 if (a_renames == renames1) {
 978                                         a = ren1->pair->two;
 979                                         b = &src_other;
 980                                 } else {
 981                                         b = ren1->pair->two;
 982                                         a = &src_other;
 983                                 }
 984                                 mfi = merge_file(o, one, a, b,
 985                                                 o->branch1, o->branch2);
 986
 987                                 if (mfi.clean &&
 988                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
 989                                     mfi.mode == ren1->pair->two->mode)
 990                                         /*
 991                                          * This messaged is part of
 992                                          * t6022 test. If you change
 993                                          * it update the test too.
 994                                          */
 995                                         output(o, 3, "Skipped %s (merged same as existing)", ren1_dst);
 996                                 else {
 997                                         if (mfi.merge || !mfi.clean)
 998                                                 output(o, 1, "Renaming %s => %s", ren1_src, ren1_dst);
 999                                         if (mfi.merge)
1000                                                 output(o, 2, "Auto-merging %s", ren1_dst);
1001                                         if (!mfi.clean) {
1002                                                 output(o, 1, "CONFLICT (rename/modify): Merge conflict in %s",
1003                                                        ren1_dst);
1004                                                 clean_merge = 0;
1005
1006                                                 if (!o->call_depth)
1007                                                         update_stages(ren1_dst,
1008                                                                       one, a, b, 1);
1009                                         }
1010                                         update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1011                                 }
1012                         }
1013                 }
1014         }
1015         string_list_clear(&a_by_dst, 0);
1016         string_list_clear(&b_by_dst, 0);
1017
1018         return clean_merge;
1019 }
1020
1021 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1022 {
1023         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1024 }
1025
1026 /* Per entry merge function */
1027 static int process_entry(struct merge_options *o,
1028                          const char *path, struct stage_data *entry)
1029 {
1030         /*
1031         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1032         print_index_entry("\tpath: ", entry);
1033         */
1034         int clean_merge = 1;
1035         unsigned o_mode = entry->stages[1].mode;
1036         unsigned a_mode = entry->stages[2].mode;
1037         unsigned b_mode = entry->stages[3].mode;
1038         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1039         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1040         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1041
1042         if (o_sha && (!a_sha || !b_sha)) {
1043                 /* Case A: Deleted in one */
1044                 if ((!a_sha && !b_sha) ||
1045                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1046                     (!a_sha && sha_eq(b_sha, o_sha))) {
1047                         /* Deleted in both or deleted in one and
1048                          * unchanged in the other */
1049                         if (a_sha)
1050                                 output(o, 2, "Removing %s", path);
1051                         /* do not touch working file if it did not exist */
1052                         remove_file(o, 1, path, !a_sha);
1053                 } else {
1054                         /* Deleted in one and changed in the other */
1055                         clean_merge = 0;
1056                         if (!a_sha) {
1057                                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1058                                        "and modified in %s. Version %s of %s left in tree.",
1059                                        path, o->branch1,
1060                                        o->branch2, o->branch2, path);
1061                                 update_file(o, 0, b_sha, b_mode, path);
1062                         } else {
1063                                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1064                                        "and modified in %s. Version %s of %s left in tree.",
1065                                        path, o->branch2,
1066                                        o->branch1, o->branch1, path);
1067                                 update_file(o, 0, a_sha, a_mode, path);
1068                         }
1069                 }
1070
1071         } else if ((!o_sha && a_sha && !b_sha) ||
1072                    (!o_sha && !a_sha && b_sha)) {
1073                 /* Case B: Added in one. */
1074                 const char *add_branch;
1075                 const char *other_branch;
1076                 unsigned mode;
1077                 const unsigned char *sha;
1078                 const char *conf;
1079
1080                 if (a_sha) {
1081                         add_branch = o->branch1;
1082                         other_branch = o->branch2;
1083                         mode = a_mode;
1084                         sha = a_sha;
1085                         conf = "file/directory";
1086                 } else {
1087                         add_branch = o->branch2;
1088                         other_branch = o->branch1;
1089                         mode = b_mode;
1090                         sha = b_sha;
1091                         conf = "directory/file";
1092                 }
1093                 if (string_list_has_string(&o->current_directory_set, path)) {
1094                         const char *new_path = unique_path(o, path, add_branch);
1095                         clean_merge = 0;
1096                         output(o, 1, "CONFLICT (%s): There is a directory with name %s in %s. "
1097                                "Adding %s as %s",
1098                                conf, path, other_branch, path, new_path);
1099                         remove_file(o, 0, path, 0);
1100                         update_file(o, 0, sha, mode, new_path);
1101                 } else {
1102                         output(o, 2, "Adding %s", path);
1103                         update_file(o, 1, sha, mode, path);
1104                 }
1105         } else if (a_sha && b_sha) {
1106                 /* Case C: Added in both (check for same permissions) and */
1107                 /* case D: Modified in both, but differently. */
1108                 const char *reason = "content";
1109                 struct merge_file_info mfi;
1110                 struct diff_filespec one, a, b;
1111
1112                 if (!o_sha) {
1113                         reason = "add/add";
1114                         o_sha = (unsigned char *)null_sha1;
1115                 }
1116                 output(o, 2, "Auto-merging %s", path);
1117                 one.path = a.path = b.path = (char *)path;
1118                 hashcpy(one.sha1, o_sha);
1119                 one.mode = o_mode;
1120                 hashcpy(a.sha1, a_sha);
1121                 a.mode = a_mode;
1122                 hashcpy(b.sha1, b_sha);
1123                 b.mode = b_mode;
1124
1125                 mfi = merge_file(o, &one, &a, &b,
1126                                  o->branch1, o->branch2);
1127
1128                 clean_merge = mfi.clean;
1129                 if (!mfi.clean) {
1130                         if (S_ISGITLINK(mfi.mode))
1131                                 reason = "submodule";
1132                         output(o, 1, "CONFLICT (%s): Merge conflict in %s",
1133                                         reason, path);
1134                 }
1135                 update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
1136         } else if (!o_sha && !a_sha && !b_sha) {
1137                 /*
1138                  * this entry was deleted altogether. a_mode == 0 means
1139                  * we had that path and want to actively remove it.
1140                  */
1141                 remove_file(o, 1, path, !a_mode);
1142         } else
1143                 die("Fatal merge failure, shouldn't happen.");
1144
1145         return clean_merge;
1146 }
1147
1148 int merge_trees(struct merge_options *o,
1149                 struct tree *head,
1150                 struct tree *merge,
1151                 struct tree *common,
1152                 struct tree **result)
1153 {
1154         int code, clean;
1155
1156         if (o->subtree_merge) {
1157                 merge = shift_tree_object(head, merge);
1158                 common = shift_tree_object(head, common);
1159         }
1160
1161         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1162                 output(o, 0, "Already uptodate!");
1163                 *result = head;
1164                 return 1;
1165         }
1166
1167         code = git_merge_trees(o->call_depth, common, head, merge);
1168
1169         if (code != 0)
1170                 die("merging of trees %s and %s failed",
1171                     sha1_to_hex(head->object.sha1),
1172                     sha1_to_hex(merge->object.sha1));
1173
1174         if (unmerged_cache()) {
1175                 struct string_list *entries, *re_head, *re_merge;
1176                 int i;
1177                 string_list_clear(&o->current_file_set, 1);
1178                 string_list_clear(&o->current_directory_set, 1);
1179                 get_files_dirs(o, head);
1180                 get_files_dirs(o, merge);
1181
1182                 entries = get_unmerged();
1183                 re_head  = get_renames(o, head, common, head, merge, entries);
1184                 re_merge = get_renames(o, merge, common, head, merge, entries);
1185                 clean = process_renames(o, re_head, re_merge);
1186                 for (i = 0; i < entries->nr; i++) {
1187                         const char *path = entries->items[i].string;
1188                         struct stage_data *e = entries->items[i].util;
1189                         if (!e->processed
1190                                 && !process_entry(o, path, e))
1191                                 clean = 0;
1192                 }
1193
1194                 string_list_clear(re_merge, 0);
1195                 string_list_clear(re_head, 0);
1196                 string_list_clear(entries, 1);
1197
1198         }
1199         else
1200                 clean = 1;
1201
1202         if (o->call_depth)
1203                 *result = write_tree_from_memory(o);
1204
1205         return clean;
1206 }
1207
1208 static struct commit_list *reverse_commit_list(struct commit_list *list)
1209 {
1210         struct commit_list *next = NULL, *current, *backup;
1211         for (current = list; current; current = backup) {
1212                 backup = current->next;
1213                 current->next = next;
1214                 next = current;
1215         }
1216         return next;
1217 }
1218
1219 /*
1220  * Merge the commits h1 and h2, return the resulting virtual
1221  * commit object and a flag indicating the cleanness of the merge.
1222  */
1223 int merge_recursive(struct merge_options *o,
1224                     struct commit *h1,
1225                     struct commit *h2,
1226                     struct commit_list *ca,
1227                     struct commit **result)
1228 {
1229         struct commit_list *iter;
1230         struct commit *merged_common_ancestors;
1231         struct tree *mrtree = mrtree;
1232         int clean;
1233
1234         if (show(o, 4)) {
1235                 output(o, 4, "Merging:");
1236                 output_commit_title(o, h1);
1237                 output_commit_title(o, h2);
1238         }
1239
1240         if (!ca) {
1241                 ca = get_merge_bases(h1, h2, 1);
1242                 ca = reverse_commit_list(ca);
1243         }
1244
1245         if (show(o, 5)) {
1246                 output(o, 5, "found %u common ancestor(s):", commit_list_count(ca));
1247                 for (iter = ca; iter; iter = iter->next)
1248                         output_commit_title(o, iter->item);
1249         }
1250
1251         merged_common_ancestors = pop_commit(&ca);
1252         if (merged_common_ancestors == NULL) {
1253                 /* if there is no common ancestor, make an empty tree */
1254                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1255
1256                 tree->object.parsed = 1;
1257                 tree->object.type = OBJ_TREE;
1258                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1259                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1260         }
1261
1262         for (iter = ca; iter; iter = iter->next) {
1263                 const char *saved_b1, *saved_b2;
1264                 o->call_depth++;
1265                 /*
1266                  * When the merge fails, the result contains files
1267                  * with conflict markers. The cleanness flag is
1268                  * ignored, it was never actually used, as result of
1269                  * merge_trees has always overwritten it: the committed
1270                  * "conflicts" were already resolved.
1271                  */
1272                 discard_cache();
1273                 saved_b1 = o->branch1;
1274                 saved_b2 = o->branch2;
1275                 o->branch1 = "Temporary merge branch 1";
1276                 o->branch2 = "Temporary merge branch 2";
1277                 merge_recursive(o, merged_common_ancestors, iter->item,
1278                                 NULL, &merged_common_ancestors);
1279                 o->branch1 = saved_b1;
1280                 o->branch2 = saved_b2;
1281                 o->call_depth--;
1282
1283                 if (!merged_common_ancestors)
1284                         die("merge returned no commit");
1285         }
1286
1287         discard_cache();
1288         if (!o->call_depth)
1289                 read_cache();
1290
1291         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
1292                             &mrtree);
1293
1294         if (o->call_depth) {
1295                 *result = make_virtual_commit(mrtree, "merged tree");
1296                 commit_list_insert(h1, &(*result)->parents);
1297                 commit_list_insert(h2, &(*result)->parents->next);
1298         }
1299         flush_output(o);
1300         return clean;
1301 }
1302
1303 static struct commit *get_ref(const unsigned char *sha1, const char *name)
1304 {
1305         struct object *object;
1306
1307         object = deref_tag(parse_object(sha1), name, strlen(name));
1308         if (!object)
1309                 return NULL;
1310         if (object->type == OBJ_TREE)
1311                 return make_virtual_commit((struct tree*)object, name);
1312         if (object->type != OBJ_COMMIT)
1313                 return NULL;
1314         if (parse_commit((struct commit *)object))
1315                 return NULL;
1316         return (struct commit *)object;
1317 }
1318
1319 int merge_recursive_generic(struct merge_options *o,
1320                             const unsigned char *head,
1321                             const unsigned char *merge,
1322                             int num_base_list,
1323                             const unsigned char **base_list,
1324                             struct commit **result)
1325 {
1326         int clean, index_fd;
1327         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1328         struct commit *head_commit = get_ref(head, o->branch1);
1329         struct commit *next_commit = get_ref(merge, o->branch2);
1330         struct commit_list *ca = NULL;
1331
1332         if (base_list) {
1333                 int i;
1334                 for (i = 0; i < num_base_list; ++i) {
1335                         struct commit *base;
1336                         if (!(base = get_ref(base_list[i], sha1_to_hex(base_list[i]))))
1337                                 return error("Could not parse object '%s'",
1338                                         sha1_to_hex(base_list[i]));
1339                         commit_list_insert(base, &ca);
1340                 }
1341         }
1342
1343         index_fd = hold_locked_index(lock, 1);
1344         clean = merge_recursive(o, head_commit, next_commit, ca,
1345                         result);
1346         if (active_cache_changed &&
1347                         (write_cache(index_fd, active_cache, active_nr) ||
1348                          commit_locked_index(lock)))
1349                 return error("Unable to write index.");
1350
1351         return clean ? 0 : 1;
1352 }
1353
1354 static int merge_recursive_config(const char *var, const char *value, void *cb)
1355 {
1356         struct merge_options *o = cb;
1357         if (!strcasecmp(var, "merge.verbosity")) {
1358                 o->verbosity = git_config_int(var, value);
1359                 return 0;
1360         }
1361         if (!strcasecmp(var, "diff.renamelimit")) {
1362                 o->diff_rename_limit = git_config_int(var, value);
1363                 return 0;
1364         }
1365         if (!strcasecmp(var, "merge.renamelimit")) {
1366                 o->merge_rename_limit = git_config_int(var, value);
1367                 return 0;
1368         }
1369         return git_xmerge_config(var, value, cb);
1370 }
1371
1372 void init_merge_options(struct merge_options *o)
1373 {
1374         memset(o, 0, sizeof(struct merge_options));
1375         o->verbosity = 2;
1376         o->buffer_output = 1;
1377         o->diff_rename_limit = -1;
1378         o->merge_rename_limit = -1;
1379         git_config(merge_recursive_config, o);
1380         if (getenv("GIT_MERGE_VERBOSITY"))
1381                 o->verbosity =
1382                         strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1383         if (o->verbosity >= 5)
1384                 o->buffer_output = 0;
1385         strbuf_init(&o->obuf, 0);
1386         memset(&o->current_file_set, 0, sizeof(struct string_list));
1387         o->current_file_set.strdup_strings = 1;
1388         memset(&o->current_directory_set, 0, sizeof(struct string_list));
1389         o->current_directory_set.strdup_strings = 1;
1390 }