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

   1 /*
   2  * Recursive Merge algorithm stolen from git-merge-recursive.py by
   3  * Fredrik Kuivinen.
   4  * The thieves were Alex Riesen and Johannes Schindelin, in June/July 2006
   5  */
   6 #include "advice.h"
   7 #include "cache.h"
   8 #include "cache-tree.h"
   9 #include "commit.h"
  10 #include "blob.h"
  11 #include "builtin.h"
  12 #include "tree-walk.h"
  13 #include "diff.h"
  14 #include "diffcore.h"
  15 #include "tag.h"
  16 #include "unpack-trees.h"
  17 #include "string-list.h"
  18 #include "xdiff-interface.h"
  19 #include "ll-merge.h"
  20 #include "attr.h"
  21 #include "merge-recursive.h"
  22 #include "dir.h"
  23 #include "submodule.h"
  24
  25 static struct tree *shift_tree_object(struct tree *one, struct tree *two,
  26                                       const char *subtree_shift)
  27 {
  28         unsigned char shifted[20];
  29
  30         if (!*subtree_shift) {
  31                 shift_tree(one->object.sha1, two->object.sha1, shifted, 0);
  32         } else {
  33                 shift_tree_by(one->object.sha1, two->object.sha1, shifted,
  34                               subtree_shift);
  35         }
  36         if (!hashcmp(two->object.sha1, shifted))
  37                 return two;
  38         return lookup_tree(shifted);
  39 }
  40
  41 /*
  42  * A virtual commit has (const char *)commit->util set to the name.
  43  */
  44
  45 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  46 {
  47         struct commit *commit = xcalloc(1, sizeof(struct commit));
  48         commit->tree = tree;
  49         commit->util = (void*)comment;
  50         /* avoid warnings */
  51         commit->object.parsed = 1;
  52         return commit;
  53 }
  54
  55 /*
  56  * Since we use get_tree_entry(), which does not put the read object into
  57  * the object pool, we cannot rely on a == b.
  58  */
  59 static int sha_eq(const unsigned char *a, const unsigned char *b)
  60 {
  61         if (!a && !b)
  62                 return 2;
  63         return a && b && hashcmp(a, b) == 0;
  64 }
  65
  66 /*
  67  * Since we want to write the index eventually, we cannot reuse the index
  68  * for these (temporary) data.
  69  */
  70 struct stage_data
  71 {
  72         struct
  73         {
  74                 unsigned mode;
  75                 unsigned char sha[20];
  76         } stages[4];
  77         unsigned processed:1;
  78 };
  79
  80 static int show(struct merge_options *o, int v)
  81 {
  82         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
  83 }
  84
  85 static void flush_output(struct merge_options *o)
  86 {
  87         if (o->obuf.len) {
  88                 fputs(o->obuf.buf, stdout);
  89                 strbuf_reset(&o->obuf);
  90         }
  91 }
  92
  93 __attribute__((format (printf, 3, 4)))
  94 static void output(struct merge_options *o, int v, const char *fmt, ...)
  95 {
  96         int len;
  97         va_list ap;
  98
  99         if (!show(o, v))
 100                 return;
 101
 102         strbuf_grow(&o->obuf, o->call_depth * 2 + 2);
 103         memset(o->obuf.buf + o->obuf.len, ' ', o->call_depth * 2);
 104         strbuf_setlen(&o->obuf, o->obuf.len + o->call_depth * 2);
 105
 106         va_start(ap, fmt);
 107         len = vsnprintf(o->obuf.buf + o->obuf.len, strbuf_avail(&o->obuf), fmt, ap);
 108         va_end(ap);
 109
 110         if (len < 0)
 111                 len = 0;
 112         if (len >= strbuf_avail(&o->obuf)) {
 113                 strbuf_grow(&o->obuf, len + 2);
 114                 va_start(ap, fmt);
 115                 len = vsnprintf(o->obuf.buf + o->obuf.len, strbuf_avail(&o->obuf), fmt, ap);
 116                 va_end(ap);
 117                 if (len >= strbuf_avail(&o->obuf)) {
 118                         die("this should not happen, your snprintf is broken");
 119                 }
 120         }
 121         strbuf_setlen(&o->obuf, o->obuf.len + len);
 122         strbuf_add(&o->obuf, "\n", 1);
 123         if (!o->buffer_output)
 124                 flush_output(o);
 125 }
 126
 127 static void output_commit_title(struct merge_options *o, struct commit *commit)
 128 {
 129         int i;
 130         flush_output(o);
 131         for (i = o->call_depth; i--;)
 132                 fputs("  ", stdout);
 133         if (commit->util)
 134                 printf("virtual %s\n", (char *)commit->util);
 135         else {
 136                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 137                 if (parse_commit(commit) != 0)
 138                         printf("(bad commit)\n");
 139                 else {
 140                         const char *title;
 141                         int len = find_commit_subject(commit->buffer, &title);
 142                         if (len)
 143                                 printf("%.*s\n", len, title);
 144                 }
 145         }
 146 }
 147
 148 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 149                 const char *path, int stage, int refresh, int options)
 150 {
 151         struct cache_entry *ce;
 152         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 153         if (!ce)
 154                 return error("addinfo_cache failed for path '%s'", path);
 155         return add_cache_entry(ce, options);
 156 }
 157
 158 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 159 {
 160         parse_tree(tree);
 161         init_tree_desc(desc, tree->buffer, tree->size);
 162 }
 163
 164 static int git_merge_trees(int index_only,
 165                            struct tree *common,
 166                            struct tree *head,
 167                            struct tree *merge)
 168 {
 169         int rc;
 170         struct tree_desc t[3];
 171         struct unpack_trees_options opts;
 172
 173         memset(&opts, 0, sizeof(opts));
 174         if (index_only)
 175                 opts.index_only = 1;
 176         else
 177                 opts.update = 1;
 178         opts.merge = 1;
 179         opts.head_idx = 2;
 180         opts.fn = threeway_merge;
 181         opts.src_index = &the_index;
 182         opts.dst_index = &the_index;
 183         opts.msgs = get_porcelain_error_msgs();
 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                 fprintf(stderr, "BUG: There are unmerged index entries:\n");
 201                 for (i = 0; i < active_nr; i++) {
 202                         struct cache_entry *ce = active_cache[i];
 203                         if (ce_stage(ce))
 204                                 fprintf(stderr, "BUG: %d %.*s", ce_stage(ce),
 205                                         (int)ce_namelen(ce), ce->name);
 206                 }
 207                 die("Bug in merge-recursive.c");
 208         }
 209
 210         if (!active_cache_tree)
 211                 active_cache_tree = cache_tree();
 212
 213         if (!cache_tree_fully_valid(active_cache_tree) &&
 214             cache_tree_update(active_cache_tree,
 215                               active_cache, active_nr, 0, 0) < 0)
 216                 die("error building trees");
 217
 218         result = lookup_tree(active_cache_tree->sha1);
 219
 220         return result;
 221 }
 222
 223 static int save_files_dirs(const unsigned char *sha1,
 224                 const char *base, int baselen, const char *path,
 225                 unsigned int mode, int stage, void *context)
 226 {
 227         int len = strlen(path);
 228         char *newpath = xmalloc(baselen + len + 1);
 229         struct merge_options *o = context;
 230
 231         memcpy(newpath, base, baselen);
 232         memcpy(newpath + baselen, path, len);
 233         newpath[baselen + len] = '\0';
 234
 235         if (S_ISDIR(mode))
 236                 string_list_insert(&o->current_directory_set, newpath);
 237         else
 238                 string_list_insert(&o->current_file_set, newpath);
 239         free(newpath);
 240
 241         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
 242 }
 243
 244 static int get_files_dirs(struct merge_options *o, struct tree *tree)
 245 {
 246         int n;
 247         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs, o))
 248                 return 0;
 249         n = o->current_file_set.nr + o->current_directory_set.nr;
 250         return n;
 251 }
 252
 253 /*
 254  * Returns an index_entry instance which doesn't have to correspond to
 255  * a real cache entry in Git's index.
 256  */
 257 static struct stage_data *insert_stage_data(const char *path,
 258                 struct tree *o, struct tree *a, struct tree *b,
 259                 struct string_list *entries)
 260 {
 261         struct string_list_item *item;
 262         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 263         get_tree_entry(o->object.sha1, path,
 264                         e->stages[1].sha, &e->stages[1].mode);
 265         get_tree_entry(a->object.sha1, path,
 266                         e->stages[2].sha, &e->stages[2].mode);
 267         get_tree_entry(b->object.sha1, path,
 268                         e->stages[3].sha, &e->stages[3].mode);
 269         item = string_list_insert(entries, path);
 270         item->util = e;
 271         return e;
 272 }
 273
 274 /*
 275  * Create a dictionary mapping file names to stage_data objects. The
 276  * dictionary contains one entry for every path with a non-zero stage entry.
 277  */
 278 static struct string_list *get_unmerged(void)
 279 {
 280         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
 281         int i;
 282
 283         unmerged->strdup_strings = 1;
 284
 285         for (i = 0; i < active_nr; i++) {
 286                 struct string_list_item *item;
 287                 struct stage_data *e;
 288                 struct cache_entry *ce = active_cache[i];
 289                 if (!ce_stage(ce))
 290                         continue;
 291
 292                 item = string_list_lookup(unmerged, ce->name);
 293                 if (!item) {
 294                         item = string_list_insert(unmerged, ce->name);
 295                         item->util = xcalloc(1, sizeof(struct stage_data));
 296                 }
 297                 e = item->util;
 298                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
 299                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 300         }
 301
 302         return unmerged;
 303 }
 304
 305 struct rename
 306 {
 307         struct diff_filepair *pair;
 308         struct stage_data *src_entry;
 309         struct stage_data *dst_entry;
 310         unsigned processed:1;
 311 };
 312
 313 /*
 314  * Get information of all renames which occurred between 'o_tree' and
 315  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 316  * 'b_tree') to be able to associate the correct cache entries with
 317  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 318  */
 319 static struct string_list *get_renames(struct merge_options *o,
 320                                        struct tree *tree,
 321                                        struct tree *o_tree,
 322                                        struct tree *a_tree,
 323                                        struct tree *b_tree,
 324                                        struct string_list *entries)
 325 {
 326         int i;
 327         struct string_list *renames;
 328         struct diff_options opts;
 329
 330         renames = xcalloc(1, sizeof(struct string_list));
 331         diff_setup(&opts);
 332         DIFF_OPT_SET(&opts, RECURSIVE);
 333         opts.detect_rename = DIFF_DETECT_RENAME;
 334         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 335                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 336                             500;
 337         opts.warn_on_too_large_rename = 1;
 338         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 339         if (diff_setup_done(&opts) < 0)
 340                 die("diff setup failed");
 341         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 342         diffcore_std(&opts);
 343         for (i = 0; i < diff_queued_diff.nr; ++i) {
 344                 struct string_list_item *item;
 345                 struct rename *re;
 346                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 347                 if (pair->status != 'R') {
 348                         diff_free_filepair(pair);
 349                         continue;
 350                 }
 351                 re = xmalloc(sizeof(*re));
 352                 re->processed = 0;
 353                 re->pair = pair;
 354                 item = string_list_lookup(entries, re->pair->one->path);
 355                 if (!item)
 356                         re->src_entry = insert_stage_data(re->pair->one->path,
 357                                         o_tree, a_tree, b_tree, entries);
 358                 else
 359                         re->src_entry = item->util;
 360
 361                 item = string_list_lookup(entries, re->pair->two->path);
 362                 if (!item)
 363                         re->dst_entry = insert_stage_data(re->pair->two->path,
 364                                         o_tree, a_tree, b_tree, entries);
 365                 else
 366                         re->dst_entry = item->util;
 367                 item = string_list_insert(renames, pair->one->path);
 368                 item->util = re;
 369         }
 370         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 371         diff_queued_diff.nr = 0;
 372         diff_flush(&opts);
 373         return renames;
 374 }
 375
 376 static int update_stages(const char *path, struct diff_filespec *o,
 377                          struct diff_filespec *a, struct diff_filespec *b,
 378                          int clear)
 379 {
 380         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 381         if (clear)
 382                 if (remove_file_from_cache(path))
 383                         return -1;
 384         if (o)
 385                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 386                         return -1;
 387         if (a)
 388                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 389                         return -1;
 390         if (b)
 391                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 392                         return -1;
 393         return 0;
 394 }
 395
 396 static int remove_file(struct merge_options *o, int clean,
 397                        const char *path, int no_wd)
 398 {
 399         int update_cache = o->call_depth || clean;
 400         int update_working_directory = !o->call_depth && !no_wd;
 401
 402         if (update_cache) {
 403                 if (remove_file_from_cache(path))
 404                         return -1;
 405         }
 406         if (update_working_directory) {
 407                 if (remove_path(path))
 408                         return -1;
 409         }
 410         return 0;
 411 }
 412
 413 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
 414 {
 415         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 416         int suffix = 0;
 417         struct stat st;
 418         char *p = newpath + strlen(path);
 419         strcpy(newpath, path);
 420         *(p++) = '~';
 421         strcpy(p, branch);
 422         for (; *p; ++p)
 423                 if ('/' == *p)
 424                         *p = '_';
 425         while (string_list_has_string(&o->current_file_set, newpath) ||
 426                string_list_has_string(&o->current_directory_set, newpath) ||
 427                lstat(newpath, &st) == 0)
 428                 sprintf(p, "_%d", suffix++);
 429
 430         string_list_insert(&o->current_file_set, newpath);
 431         return newpath;
 432 }
 433
 434 static void flush_buffer(int fd, const char *buf, unsigned long size)
 435 {
 436         while (size > 0) {
 437                 long ret = write_in_full(fd, buf, size);
 438                 if (ret < 0) {
 439                         /* Ignore epipe */
 440                         if (errno == EPIPE)
 441                                 break;
 442                         die_errno("merge-recursive");
 443                 } else if (!ret) {
 444                         die("merge-recursive: disk full?");
 445                 }
 446                 size -= ret;
 447                 buf += ret;
 448         }
 449 }
 450
 451 static int would_lose_untracked(const char *path)
 452 {
 453         int pos = cache_name_pos(path, strlen(path));
 454
 455         if (pos < 0)
 456                 pos = -1 - pos;
 457         while (pos < active_nr &&
 458                !strcmp(path, active_cache[pos]->name)) {
 459                 /*
 460                  * If stage #0, it is definitely tracked.
 461                  * If it has stage #2 then it was tracked
 462                  * before this merge started.  All other
 463                  * cases the path was not tracked.
 464                  */
 465                 switch (ce_stage(active_cache[pos])) {
 466                 case 0:
 467                 case 2:
 468                         return 0;
 469                 }
 470                 pos++;
 471         }
 472         return file_exists(path);
 473 }
 474
 475 static int make_room_for_path(const char *path)
 476 {
 477         int status;
 478         const char *msg = "failed to create path '%s'%s";
 479
 480         status = safe_create_leading_directories_const(path);
 481         if (status) {
 482                 if (status == -3) {
 483                         /* something else exists */
 484                         error(msg, path, ": perhaps a D/F conflict?");
 485                         return -1;
 486                 }
 487                 die(msg, path, "");
 488         }
 489
 490         /*
 491          * Do not unlink a file in the work tree if we are not
 492          * tracking it.
 493          */
 494         if (would_lose_untracked(path))
 495                 return error("refusing to lose untracked file at '%s'",
 496                              path);
 497
 498         /* Successful unlink is good.. */
 499         if (!unlink(path))
 500                 return 0;
 501         /* .. and so is no existing file */
 502         if (errno == ENOENT)
 503                 return 0;
 504         /* .. but not some other error (who really cares what?) */
 505         return error(msg, path, ": perhaps a D/F conflict?");
 506 }
 507
 508 static void update_file_flags(struct merge_options *o,
 509                               const unsigned char *sha,
 510                               unsigned mode,
 511                               const char *path,
 512                               int update_cache,
 513                               int update_wd)
 514 {
 515         if (o->call_depth)
 516                 update_wd = 0;
 517
 518         if (update_wd) {
 519                 enum object_type type;
 520                 void *buf;
 521                 unsigned long size;
 522
 523                 if (S_ISGITLINK(mode)) {
 524                         /*
 525                          * We may later decide to recursively descend into
 526                          * the submodule directory and update its index
 527                          * and/or work tree, but we do not do that now.
 528                          */
 529                         update_wd = 0;
 530                         goto update_index;
 531                 }
 532
 533                 buf = read_sha1_file(sha, &type, &size);
 534                 if (!buf)
 535                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 536                 if (type != OBJ_BLOB)
 537                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 538                 if (S_ISREG(mode)) {
 539                         struct strbuf strbuf = STRBUF_INIT;
 540                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
 541                                 free(buf);
 542                                 size = strbuf.len;
 543                                 buf = strbuf_detach(&strbuf, NULL);
 544                         }
 545                 }
 546
 547                 if (make_room_for_path(path) < 0) {
 548                         update_wd = 0;
 549                         free(buf);
 550                         goto update_index;
 551                 }
 552                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 553                         int fd;
 554                         if (mode & 0100)
 555                                 mode = 0777;
 556                         else
 557                                 mode = 0666;
 558                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 559                         if (fd < 0)
 560                                 die_errno("failed to open '%s'", path);
 561                         flush_buffer(fd, buf, size);
 562                         close(fd);
 563                 } else if (S_ISLNK(mode)) {
 564                         char *lnk = xmemdupz(buf, size);
 565                         safe_create_leading_directories_const(path);
 566                         unlink(path);
 567                         if (symlink(lnk, path))
 568                                 die_errno("failed to symlink '%s'", path);
 569                         free(lnk);
 570                 } else
 571                         die("do not know what to do with %06o %s '%s'",
 572                             mode, sha1_to_hex(sha), path);
 573                 free(buf);
 574         }
 575  update_index:
 576         if (update_cache)
 577                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 578 }
 579
 580 static void update_file(struct merge_options *o,
 581                         int clean,
 582                         const unsigned char *sha,
 583                         unsigned mode,
 584                         const char *path)
 585 {
 586         update_file_flags(o, sha, mode, path, o->call_depth || clean, !o->call_depth);
 587 }
 588
 589 /* Low level file merging, update and removal */
 590
 591 struct merge_file_info
 592 {
 593         unsigned char sha[20];
 594         unsigned mode;
 595         unsigned clean:1,
 596                  merge:1;
 597 };
 598
 599 static int merge_3way(struct merge_options *o,
 600                       mmbuffer_t *result_buf,
 601                       struct diff_filespec *one,
 602                       struct diff_filespec *a,
 603                       struct diff_filespec *b,
 604                       const char *branch1,
 605                       const char *branch2)
 606 {
 607         mmfile_t orig, src1, src2;
 608         char *base_name, *name1, *name2;
 609         int merge_status;
 610         int favor;
 611
 612         if (o->call_depth)
 613                 favor = 0;
 614         else {
 615                 switch (o->recursive_variant) {
 616                 case MERGE_RECURSIVE_OURS:
 617                         favor = XDL_MERGE_FAVOR_OURS;
 618                         break;
 619                 case MERGE_RECURSIVE_THEIRS:
 620                         favor = XDL_MERGE_FAVOR_THEIRS;
 621                         break;
 622                 default:
 623                         favor = 0;
 624                         break;
 625                 }
 626         }
 627
 628         if (strcmp(a->path, b->path) ||
 629             (o->ancestor != NULL && strcmp(a->path, one->path) != 0)) {
 630                 base_name = o->ancestor == NULL ? NULL :
 631                         xstrdup(mkpath("%s:%s", o->ancestor, one->path));
 632                 name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 633                 name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 634         } else {
 635                 base_name = o->ancestor == NULL ? NULL :
 636                         xstrdup(mkpath("%s", o->ancestor));
 637                 name1 = xstrdup(mkpath("%s", branch1));
 638                 name2 = xstrdup(mkpath("%s", branch2));
 639         }
 640
 641         read_mmblob(&orig, one->sha1);
 642         read_mmblob(&src1, a->sha1);
 643         read_mmblob(&src2, b->sha1);
 644
 645         merge_status = ll_merge(result_buf, a->path, &orig, base_name,
 646                                 &src1, name1, &src2, name2,
 647                                 (!!o->call_depth) | (favor << 1));
 648
 649         free(name1);
 650         free(name2);
 651         free(orig.ptr);
 652         free(src1.ptr);
 653         free(src2.ptr);
 654         return merge_status;
 655 }
 656
 657 static struct merge_file_info merge_file(struct merge_options *o,
 658                                          struct diff_filespec *one,
 659                                          struct diff_filespec *a,
 660                                          struct diff_filespec *b,
 661                                          const char *branch1,
 662                                          const char *branch2)
 663 {
 664         struct merge_file_info result;
 665         result.merge = 0;
 666         result.clean = 1;
 667
 668         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 669                 result.clean = 0;
 670                 if (S_ISREG(a->mode)) {
 671                         result.mode = a->mode;
 672                         hashcpy(result.sha, a->sha1);
 673                 } else {
 674                         result.mode = b->mode;
 675                         hashcpy(result.sha, b->sha1);
 676                 }
 677         } else {
 678                 if (!sha_eq(a->sha1, one->sha1) && !sha_eq(b->sha1, one->sha1))
 679                         result.merge = 1;
 680
 681                 /*
 682                  * Merge modes
 683                  */
 684                 if (a->mode == b->mode || a->mode == one->mode)
 685                         result.mode = b->mode;
 686                 else {
 687                         result.mode = a->mode;
 688                         if (b->mode != one->mode) {
 689                                 result.clean = 0;
 690                                 result.merge = 1;
 691                         }
 692                 }
 693
 694                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, one->sha1))
 695                         hashcpy(result.sha, b->sha1);
 696                 else if (sha_eq(b->sha1, one->sha1))
 697                         hashcpy(result.sha, a->sha1);
 698                 else if (S_ISREG(a->mode)) {
 699                         mmbuffer_t result_buf;
 700                         int merge_status;
 701
 702                         merge_status = merge_3way(o, &result_buf, one, a, b,
 703                                                   branch1, branch2);
 704
 705                         if ((merge_status < 0) || !result_buf.ptr)
 706                                 die("Failed to execute internal merge");
 707
 708                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 709                                             blob_type, result.sha))
 710                                 die("Unable to add %s to database",
 711                                     a->path);
 712
 713                         free(result_buf.ptr);
 714                         result.clean = (merge_status == 0);
 715                 } else if (S_ISGITLINK(a->mode)) {
 716                         result.clean = merge_submodule(result.sha, one->path, one->sha1,
 717                                                        a->sha1, b->sha1);
 718                 } else if (S_ISLNK(a->mode)) {
 719                         hashcpy(result.sha, a->sha1);
 720
 721                         if (!sha_eq(a->sha1, b->sha1))
 722                                 result.clean = 0;
 723                 } else {
 724                         die("unsupported object type in the tree");
 725                 }
 726         }
 727
 728         return result;
 729 }
 730
 731 static void conflict_rename_rename(struct merge_options *o,
 732                                    struct rename *ren1,
 733                                    const char *branch1,
 734                                    struct rename *ren2,
 735                                    const char *branch2)
 736 {
 737         char *del[2];
 738         int delp = 0;
 739         const char *ren1_dst = ren1->pair->two->path;
 740         const char *ren2_dst = ren2->pair->two->path;
 741         const char *dst_name1 = ren1_dst;
 742         const char *dst_name2 = ren2_dst;
 743         if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
 744                 dst_name1 = del[delp++] = unique_path(o, ren1_dst, branch1);
 745                 output(o, 1, "%s is a directory in %s adding as %s instead",
 746                        ren1_dst, branch2, dst_name1);
 747                 remove_file(o, 0, ren1_dst, 0);
 748         }
 749         if (string_list_has_string(&o->current_directory_set, ren2_dst)) {
 750                 dst_name2 = del[delp++] = unique_path(o, ren2_dst, branch2);
 751                 output(o, 1, "%s is a directory in %s adding as %s instead",
 752                        ren2_dst, branch1, dst_name2);
 753                 remove_file(o, 0, ren2_dst, 0);
 754         }
 755         if (o->call_depth) {
 756                 remove_file_from_cache(dst_name1);
 757                 remove_file_from_cache(dst_name2);
 758                 /*
 759                  * Uncomment to leave the conflicting names in the resulting tree
 760                  *
 761                  * update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
 762                  * update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
 763                  */
 764         } else {
 765                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
 766                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
 767         }
 768         while (delp--)
 769                 free(del[delp]);
 770 }
 771
 772 static void conflict_rename_dir(struct merge_options *o,
 773                                 struct rename *ren1,
 774                                 const char *branch1)
 775 {
 776         char *new_path = unique_path(o, ren1->pair->two->path, branch1);
 777         output(o, 1, "Renaming %s to %s instead", ren1->pair->one->path, new_path);
 778         remove_file(o, 0, ren1->pair->two->path, 0);
 779         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
 780         free(new_path);
 781 }
 782
 783 static void conflict_rename_rename_2(struct merge_options *o,
 784                                      struct rename *ren1,
 785                                      const char *branch1,
 786                                      struct rename *ren2,
 787                                      const char *branch2)
 788 {
 789         char *new_path1 = unique_path(o, ren1->pair->two->path, branch1);
 790         char *new_path2 = unique_path(o, ren2->pair->two->path, branch2);
 791         output(o, 1, "Renaming %s to %s and %s to %s instead",
 792                ren1->pair->one->path, new_path1,
 793                ren2->pair->one->path, new_path2);
 794         remove_file(o, 0, ren1->pair->two->path, 0);
 795         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 796         update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 797         free(new_path2);
 798         free(new_path1);
 799 }
 800
 801 static int process_renames(struct merge_options *o,
 802                            struct string_list *a_renames,
 803                            struct string_list *b_renames)
 804 {
 805         int clean_merge = 1, i, j;
 806         struct string_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
 807         const struct rename *sre;
 808
 809         for (i = 0; i < a_renames->nr; i++) {
 810                 sre = a_renames->items[i].util;
 811                 string_list_insert(&a_by_dst, sre->pair->two->path)->util
 812                         = sre->dst_entry;
 813         }
 814         for (i = 0; i < b_renames->nr; i++) {
 815                 sre = b_renames->items[i].util;
 816                 string_list_insert(&b_by_dst, sre->pair->two->path)->util
 817                         = sre->dst_entry;
 818         }
 819
 820         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 821                 char *src;
 822                 struct string_list *renames1, *renames2Dst;
 823                 struct rename *ren1 = NULL, *ren2 = NULL;
 824                 const char *branch1, *branch2;
 825                 const char *ren1_src, *ren1_dst;
 826
 827                 if (i >= a_renames->nr) {
 828                         ren2 = b_renames->items[j++].util;
 829                 } else if (j >= b_renames->nr) {
 830                         ren1 = a_renames->items[i++].util;
 831                 } else {
 832                         int compare = strcmp(a_renames->items[i].string,
 833                                              b_renames->items[j].string);
 834                         if (compare <= 0)
 835                                 ren1 = a_renames->items[i++].util;
 836                         if (compare >= 0)
 837                                 ren2 = b_renames->items[j++].util;
 838                 }
 839
 840                 /* TODO: refactor, so that 1/2 are not needed */
 841                 if (ren1) {
 842                         renames1 = a_renames;
 843                         renames2Dst = &b_by_dst;
 844                         branch1 = o->branch1;
 845                         branch2 = o->branch2;
 846                 } else {
 847                         struct rename *tmp;
 848                         renames1 = b_renames;
 849                         renames2Dst = &a_by_dst;
 850                         branch1 = o->branch2;
 851                         branch2 = o->branch1;
 852                         tmp = ren2;
 853                         ren2 = ren1;
 854                         ren1 = tmp;
 855                 }
 856                 src = ren1->pair->one->path;
 857
 858                 ren1->dst_entry->processed = 1;
 859                 ren1->src_entry->processed = 1;
 860
 861                 if (ren1->processed)
 862                         continue;
 863                 ren1->processed = 1;
 864
 865                 ren1_src = ren1->pair->one->path;
 866                 ren1_dst = ren1->pair->two->path;
 867
 868                 if (ren2) {
 869                         const char *ren2_src = ren2->pair->one->path;
 870                         const char *ren2_dst = ren2->pair->two->path;
 871                         /* Renamed in 1 and renamed in 2 */
 872                         if (strcmp(ren1_src, ren2_src) != 0)
 873                                 die("ren1.src != ren2.src");
 874                         ren2->dst_entry->processed = 1;
 875                         ren2->processed = 1;
 876                         if (strcmp(ren1_dst, ren2_dst) != 0) {
 877                                 clean_merge = 0;
 878                                 output(o, 1, "CONFLICT (rename/rename): "
 879                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
 880                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
 881                                        src, ren1_dst, branch1,
 882                                        src, ren2_dst, branch2,
 883                                        o->call_depth ? " (left unresolved)": "");
 884                                 if (o->call_depth) {
 885                                         remove_file_from_cache(src);
 886                                         update_file(o, 0, ren1->pair->one->sha1,
 887                                                     ren1->pair->one->mode, src);
 888                                 }
 889                                 conflict_rename_rename(o, ren1, branch1, ren2, branch2);
 890                         } else {
 891                                 struct merge_file_info mfi;
 892                                 remove_file(o, 1, ren1_src, 1);
 893                                 mfi = merge_file(o,
 894                                                  ren1->pair->one,
 895                                                  ren1->pair->two,
 896                                                  ren2->pair->two,
 897                                                  branch1,
 898                                                  branch2);
 899                                 if (mfi.merge || !mfi.clean)
 900                                         output(o, 1, "Renaming %s->%s", src, ren1_dst);
 901
 902                                 if (mfi.merge)
 903                                         output(o, 2, "Auto-merging %s", ren1_dst);
 904
 905                                 if (!mfi.clean) {
 906                                         output(o, 1, "CONFLICT (content): merge conflict in %s",
 907                                                ren1_dst);
 908                                         clean_merge = 0;
 909
 910                                         if (!o->call_depth)
 911                                                 update_stages(ren1_dst,
 912                                                               ren1->pair->one,
 913                                                               ren1->pair->two,
 914                                                               ren2->pair->two,
 915                                                               1 /* clear */);
 916                                 }
 917                                 update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 918                         }
 919                 } else {
 920                         /* Renamed in 1, maybe changed in 2 */
 921                         struct string_list_item *item;
 922                         /* we only use sha1 and mode of these */
 923                         struct diff_filespec src_other, dst_other;
 924                         int try_merge, stage = a_renames == renames1 ? 3: 2;
 925
 926                         remove_file(o, 1, ren1_src, o->call_depth || stage == 3);
 927
 928                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
 929                         src_other.mode = ren1->src_entry->stages[stage].mode;
 930                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
 931                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
 932
 933                         try_merge = 0;
 934
 935                         if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
 936                                 clean_merge = 0;
 937                                 output(o, 1, "CONFLICT (rename/directory): Rename %s->%s in %s "
 938                                        " directory %s added in %s",
 939                                        ren1_src, ren1_dst, branch1,
 940                                        ren1_dst, branch2);
 941                                 conflict_rename_dir(o, ren1, branch1);
 942                         } else if (sha_eq(src_other.sha1, null_sha1)) {
 943                                 clean_merge = 0;
 944                                 output(o, 1, "CONFLICT (rename/delete): Rename %s->%s in %s "
 945                                        "and deleted in %s",
 946                                        ren1_src, ren1_dst, branch1,
 947                                        branch2);
 948                                 update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
 949                                 if (!o->call_depth)
 950                                         update_stages(ren1_dst, NULL,
 951                                                         branch1 == o->branch1 ?
 952                                                         ren1->pair->two : NULL,
 953                                                         branch1 == o->branch1 ?
 954                                                         NULL : ren1->pair->two, 1);
 955                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
 956                                 const char *new_path;
 957                                 clean_merge = 0;
 958                                 try_merge = 1;
 959                                 output(o, 1, "CONFLICT (rename/add): Rename %s->%s in %s. "
 960                                        "%s added in %s",
 961                                        ren1_src, ren1_dst, branch1,
 962                                        ren1_dst, branch2);
 963                                 if (o->call_depth) {
 964                                         struct merge_file_info mfi;
 965                                         struct diff_filespec one, a, b;
 966
 967                                         one.path = a.path = b.path =
 968                                                 (char *)ren1_dst;
 969                                         hashcpy(one.sha1, null_sha1);
 970                                         one.mode = 0;
 971                                         hashcpy(a.sha1, ren1->pair->two->sha1);
 972                                         a.mode = ren1->pair->two->mode;
 973                                         hashcpy(b.sha1, dst_other.sha1);
 974                                         b.mode = dst_other.mode;
 975                                         mfi = merge_file(o, &one, &a, &b,
 976                                                          branch1,
 977                                                          branch2);
 978                                         output(o, 1, "Adding merged %s", ren1_dst);
 979                                         update_file(o, 0,
 980                                                     mfi.sha,
 981                                                     mfi.mode,
 982                                                     ren1_dst);
 983                                 } else {
 984                                         new_path = unique_path(o, ren1_dst, branch2);
 985                                         output(o, 1, "Adding as %s instead", new_path);
 986                                         update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
 987                                 }
 988                         } else if ((item = string_list_lookup(renames2Dst, ren1_dst))) {
 989                                 ren2 = item->util;
 990                                 clean_merge = 0;
 991                                 ren2->processed = 1;
 992                                 output(o, 1, "CONFLICT (rename/rename): "
 993                                        "Rename %s->%s in %s. "
 994                                        "Rename %s->%s in %s",
 995                                        ren1_src, ren1_dst, branch1,
 996                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
 997                                 conflict_rename_rename_2(o, ren1, branch1, ren2, branch2);
 998                         } else
 999                                 try_merge = 1;
1000
1001                         if (try_merge) {
1002                                 struct diff_filespec *one, *a, *b;
1003                                 struct merge_file_info mfi;
1004                                 src_other.path = (char *)ren1_src;
1005
1006                                 one = ren1->pair->one;
1007                                 if (a_renames == renames1) {
1008                                         a = ren1->pair->two;
1009                                         b = &src_other;
1010                                 } else {
1011                                         b = ren1->pair->two;
1012                                         a = &src_other;
1013                                 }
1014                                 mfi = merge_file(o, one, a, b,
1015                                                 o->branch1, o->branch2);
1016
1017                                 if (mfi.clean &&
1018                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
1019                                     mfi.mode == ren1->pair->two->mode) {
1020                                         /*
1021                                          * This messaged is part of
1022                                          * t6022 test. If you change
1023                                          * it update the test too.
1024                                          */
1025                                         output(o, 3, "Skipped %s (merged same as existing)", ren1_dst);
1026
1027                                         /* There may be higher stage entries left
1028                                          * in the index (e.g. due to a D/F
1029                                          * conflict) that need to be resolved.
1030                                          */
1031                                         for (i = 1; i <= 3; i++) {
1032                                                 if (!ren1->dst_entry->stages[i].mode)
1033                                                         continue;
1034                                                 ren1->dst_entry->processed = 0;
1035                                                 break;
1036                                         }
1037                                 } else {
1038                                         if (mfi.merge || !mfi.clean)
1039                                                 output(o, 1, "Renaming %s => %s", ren1_src, ren1_dst);
1040                                         if (mfi.merge)
1041                                                 output(o, 2, "Auto-merging %s", ren1_dst);
1042                                         if (!mfi.clean) {
1043                                                 output(o, 1, "CONFLICT (rename/modify): Merge conflict in %s",
1044                                                        ren1_dst);
1045                                                 clean_merge = 0;
1046
1047                                                 if (!o->call_depth)
1048                                                         update_stages(ren1_dst,
1049                                                                       one, a, b, 1);
1050                                         }
1051                                         update_file(o, mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1052                                 }
1053                         }
1054                 }
1055         }
1056         string_list_clear(&a_by_dst, 0);
1057         string_list_clear(&b_by_dst, 0);
1058
1059         return clean_merge;
1060 }
1061
1062 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1063 {
1064         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1065 }
1066
1067 /* Per entry merge function */
1068 static int process_entry(struct merge_options *o,
1069                          const char *path, struct stage_data *entry)
1070 {
1071         /*
1072         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1073         print_index_entry("\tpath: ", entry);
1074         */
1075         int clean_merge = 1;
1076         unsigned o_mode = entry->stages[1].mode;
1077         unsigned a_mode = entry->stages[2].mode;
1078         unsigned b_mode = entry->stages[3].mode;
1079         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1080         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1081         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1082
1083         entry->processed = 1;
1084         if (o_sha && (!a_sha || !b_sha)) {
1085                 /* Case A: Deleted in one */
1086                 if ((!a_sha && !b_sha) ||
1087                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1088                     (!a_sha && sha_eq(b_sha, o_sha))) {
1089                         /* Deleted in both or deleted in one and
1090                          * unchanged in the other */
1091                         if (a_sha)
1092                                 output(o, 2, "Removing %s", path);
1093                         /* do not touch working file if it did not exist */
1094                         remove_file(o, 1, path, !a_sha);
1095                 } else {
1096                         /* Deleted in one and changed in the other */
1097                         clean_merge = 0;
1098                         if (!a_sha) {
1099                                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1100                                        "and modified in %s. Version %s of %s left in tree.",
1101                                        path, o->branch1,
1102                                        o->branch2, o->branch2, path);
1103                                 update_file(o, 0, b_sha, b_mode, path);
1104                         } else {
1105                                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1106                                        "and modified in %s. Version %s of %s left in tree.",
1107                                        path, o->branch2,
1108                                        o->branch1, o->branch1, path);
1109                                 update_file(o, 0, a_sha, a_mode, path);
1110                         }
1111                 }
1112
1113         } else if ((!o_sha && a_sha && !b_sha) ||
1114                    (!o_sha && !a_sha && b_sha)) {
1115                 /* Case B: Added in one. */
1116                 unsigned mode;
1117                 const unsigned char *sha;
1118
1119                 if (a_sha) {
1120                         mode = a_mode;
1121                         sha = a_sha;
1122                 } else {
1123                         mode = b_mode;
1124                         sha = b_sha;
1125                 }
1126                 if (string_list_has_string(&o->current_directory_set, path)) {
1127                         /* Handle D->F conflicts after all subfiles */
1128                         entry->processed = 0;
1129                         /* But get any file out of the way now, so conflicted
1130                          * entries below the directory of the same name can
1131                          * be put in the working directory.
1132                          */
1133                         if (a_sha)
1134                                 output(o, 2, "Removing %s", path);
1135                         /* do not touch working file if it did not exist */
1136                         remove_file(o, 0, path, !a_sha);
1137                         return 1; /* Assume clean till processed */
1138                 } else {
1139                         output(o, 2, "Adding %s", path);
1140                         update_file(o, 1, sha, mode, path);
1141                 }
1142         } else if (a_sha && b_sha) {
1143                 /* Case C: Added in both (check for same permissions) and */
1144                 /* case D: Modified in both, but differently. */
1145                 const char *reason = "content";
1146                 struct merge_file_info mfi;
1147                 struct diff_filespec one, a, b;
1148
1149                 if (!o_sha) {
1150                         reason = "add/add";
1151                         o_sha = (unsigned char *)null_sha1;
1152                 }
1153                 output(o, 2, "Auto-merging %s", path);
1154                 one.path = a.path = b.path = (char *)path;
1155                 hashcpy(one.sha1, o_sha);
1156                 one.mode = o_mode;
1157                 hashcpy(a.sha1, a_sha);
1158                 a.mode = a_mode;
1159                 hashcpy(b.sha1, b_sha);
1160                 b.mode = b_mode;
1161
1162                 mfi = merge_file(o, &one, &a, &b,
1163                                  o->branch1, o->branch2);
1164
1165                 clean_merge = mfi.clean;
1166                 if (!mfi.clean) {
1167                         if (S_ISGITLINK(mfi.mode))
1168                                 reason = "submodule";
1169                         output(o, 1, "CONFLICT (%s): Merge conflict in %s",
1170                                         reason, path);
1171                 }
1172                 update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
1173         } else if (!o_sha && !a_sha && !b_sha) {
1174                 /*
1175                  * this entry was deleted altogether. a_mode == 0 means
1176                  * we had that path and want to actively remove it.
1177                  */
1178                 remove_file(o, 1, path, !a_mode);
1179         } else
1180                 die("Fatal merge failure, shouldn't happen.");
1181
1182         return clean_merge;
1183 }
1184
1185 /*
1186  * Per entry merge function for D/F conflicts, to be called only after
1187  * all files below dir have been processed.  We do this because in the
1188  * cases we can cleanly resolve D/F conflicts, process_entry() can clean
1189  * out all the files below the directory for us.
1190  */
1191 static int process_df_entry(struct merge_options *o,
1192                          const char *path, struct stage_data *entry)
1193 {
1194         int clean_merge = 1;
1195         unsigned o_mode = entry->stages[1].mode;
1196         unsigned a_mode = entry->stages[2].mode;
1197         unsigned b_mode = entry->stages[3].mode;
1198         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1199         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1200         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1201         const char *add_branch;
1202         const char *other_branch;
1203         unsigned mode;
1204         const unsigned char *sha;
1205         const char *conf;
1206         struct stat st;
1207
1208         /* We currently only handle D->F cases */
1209         assert((!o_sha && a_sha && !b_sha) ||
1210                (!o_sha && !a_sha && b_sha));
1211
1212         entry->processed = 1;
1213
1214         if (a_sha) {
1215                 add_branch = o->branch1;
1216                 other_branch = o->branch2;
1217                 mode = a_mode;
1218                 sha = a_sha;
1219                 conf = "file/directory";
1220         } else {
1221                 add_branch = o->branch2;
1222                 other_branch = o->branch1;
1223                 mode = b_mode;
1224                 sha = b_sha;
1225                 conf = "directory/file";
1226         }
1227         if (lstat(path, &st) == 0 && S_ISDIR(st.st_mode)) {
1228                 const char *new_path = unique_path(o, path, add_branch);
1229                 clean_merge = 0;
1230                 output(o, 1, "CONFLICT (%s): There is a directory with name %s in %s. "
1231                        "Adding %s as %s",
1232                        conf, path, other_branch, path, new_path);
1233                 remove_file(o, 0, path, 0);
1234                 update_file(o, 0, sha, mode, new_path);
1235         } else {
1236                 output(o, 2, "Adding %s", path);
1237                 update_file(o, 1, sha, mode, path);
1238         }
1239
1240         return clean_merge;
1241 }
1242
1243 struct unpack_trees_error_msgs get_porcelain_error_msgs(void)
1244 {
1245         struct unpack_trees_error_msgs msgs = {
1246                 /* would_overwrite */
1247                 "Your local changes to '%s' would be overwritten by merge.  Aborting.",
1248                 /* not_uptodate_file */
1249                 "Your local changes to '%s' would be overwritten by merge.  Aborting.",
1250                 /* not_uptodate_dir */
1251                 "Updating '%s' would lose untracked files in it.  Aborting.",
1252                 /* would_lose_untracked */
1253                 "Untracked working tree file '%s' would be %s by merge.  Aborting",
1254                 /* bind_overlap -- will not happen here */
1255                 NULL,
1256         };
1257         if (advice_commit_before_merge) {
1258                 msgs.would_overwrite = msgs.not_uptodate_file =
1259                         "Your local changes to '%s' would be overwritten by merge.  Aborting.\n"
1260                         "Please, commit your changes or stash them before you can merge.";
1261         }
1262         return msgs;
1263 }
1264
1265 int merge_trees(struct merge_options *o,
1266                 struct tree *head,
1267                 struct tree *merge,
1268                 struct tree *common,
1269                 struct tree **result)
1270 {
1271         int code, clean;
1272
1273         if (o->subtree_shift) {
1274                 merge = shift_tree_object(head, merge, o->subtree_shift);
1275                 common = shift_tree_object(head, common, o->subtree_shift);
1276         }
1277
1278         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1279                 output(o, 0, "Already up-to-date!");
1280                 *result = head;
1281                 return 1;
1282         }
1283
1284         code = git_merge_trees(o->call_depth, common, head, merge);
1285
1286         if (code != 0) {
1287                 if (show(o, 4) || o->call_depth)
1288                         die("merging of trees %s and %s failed",
1289                             sha1_to_hex(head->object.sha1),
1290                             sha1_to_hex(merge->object.sha1));
1291                 else
1292                         exit(128);
1293         }
1294
1295         if (unmerged_cache()) {
1296                 struct string_list *entries, *re_head, *re_merge;
1297                 int i;
1298                 string_list_clear(&o->current_file_set, 1);
1299                 string_list_clear(&o->current_directory_set, 1);
1300                 get_files_dirs(o, head);
1301                 get_files_dirs(o, merge);
1302
1303                 entries = get_unmerged();
1304                 re_head  = get_renames(o, head, common, head, merge, entries);
1305                 re_merge = get_renames(o, merge, common, head, merge, entries);
1306                 clean = process_renames(o, re_head, re_merge);
1307                 for (i = 0; i < entries->nr; i++) {
1308                         const char *path = entries->items[i].string;
1309                         struct stage_data *e = entries->items[i].util;
1310                         if (!e->processed
1311                                 && !process_entry(o, path, e))
1312                                 clean = 0;
1313                 }
1314                 for (i = 0; i < entries->nr; i++) {
1315                         const char *path = entries->items[i].string;
1316                         struct stage_data *e = entries->items[i].util;
1317                         if (!e->processed
1318                                 && !process_df_entry(o, path, e))
1319                                 clean = 0;
1320                 }
1321
1322                 string_list_clear(re_merge, 0);
1323                 string_list_clear(re_head, 0);
1324                 string_list_clear(entries, 1);
1325
1326         }
1327         else
1328                 clean = 1;
1329
1330         if (o->call_depth)
1331                 *result = write_tree_from_memory(o);
1332
1333         return clean;
1334 }
1335
1336 static struct commit_list *reverse_commit_list(struct commit_list *list)
1337 {
1338         struct commit_list *next = NULL, *current, *backup;
1339         for (current = list; current; current = backup) {
1340                 backup = current->next;
1341                 current->next = next;
1342                 next = current;
1343         }
1344         return next;
1345 }
1346
1347 /*
1348  * Merge the commits h1 and h2, return the resulting virtual
1349  * commit object and a flag indicating the cleanness of the merge.
1350  */
1351 int merge_recursive(struct merge_options *o,
1352                     struct commit *h1,
1353                     struct commit *h2,
1354                     struct commit_list *ca,
1355                     struct commit **result)
1356 {
1357         struct commit_list *iter;
1358         struct commit *merged_common_ancestors;
1359         struct tree *mrtree = mrtree;
1360         int clean;
1361
1362         if (show(o, 4)) {
1363                 output(o, 4, "Merging:");
1364                 output_commit_title(o, h1);
1365                 output_commit_title(o, h2);
1366         }
1367
1368         if (!ca) {
1369                 ca = get_merge_bases(h1, h2, 1);
1370                 ca = reverse_commit_list(ca);
1371         }
1372
1373         if (show(o, 5)) {
1374                 output(o, 5, "found %u common ancestor(s):", commit_list_count(ca));
1375                 for (iter = ca; iter; iter = iter->next)
1376                         output_commit_title(o, iter->item);
1377         }
1378
1379         merged_common_ancestors = pop_commit(&ca);
1380         if (merged_common_ancestors == NULL) {
1381                 /* if there is no common ancestor, make an empty tree */
1382                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1383
1384                 tree->object.parsed = 1;
1385                 tree->object.type = OBJ_TREE;
1386                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1387                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1388         }
1389
1390         for (iter = ca; iter; iter = iter->next) {
1391                 const char *saved_b1, *saved_b2;
1392                 o->call_depth++;
1393                 /*
1394                  * When the merge fails, the result contains files
1395                  * with conflict markers. The cleanness flag is
1396                  * ignored, it was never actually used, as result of
1397                  * merge_trees has always overwritten it: the committed
1398                  * "conflicts" were already resolved.
1399                  */
1400                 discard_cache();
1401                 saved_b1 = o->branch1;
1402                 saved_b2 = o->branch2;
1403                 o->branch1 = "Temporary merge branch 1";
1404                 o->branch2 = "Temporary merge branch 2";
1405                 merge_recursive(o, merged_common_ancestors, iter->item,
1406                                 NULL, &merged_common_ancestors);
1407                 o->branch1 = saved_b1;
1408                 o->branch2 = saved_b2;
1409                 o->call_depth--;
1410
1411                 if (!merged_common_ancestors)
1412                         die("merge returned no commit");
1413         }
1414
1415         discard_cache();
1416         if (!o->call_depth)
1417                 read_cache();
1418
1419         o->ancestor = "merged common ancestors";
1420         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
1421                             &mrtree);
1422
1423         if (o->call_depth) {
1424                 *result = make_virtual_commit(mrtree, "merged tree");
1425                 commit_list_insert(h1, &(*result)->parents);
1426                 commit_list_insert(h2, &(*result)->parents->next);
1427         }
1428         flush_output(o);
1429         return clean;
1430 }
1431
1432 static struct commit *get_ref(const unsigned char *sha1, const char *name)
1433 {
1434         struct object *object;
1435
1436         object = deref_tag(parse_object(sha1), name, strlen(name));
1437         if (!object)
1438                 return NULL;
1439         if (object->type == OBJ_TREE)
1440                 return make_virtual_commit((struct tree*)object, name);
1441         if (object->type != OBJ_COMMIT)
1442                 return NULL;
1443         if (parse_commit((struct commit *)object))
1444                 return NULL;
1445         return (struct commit *)object;
1446 }
1447
1448 int merge_recursive_generic(struct merge_options *o,
1449                             const unsigned char *head,
1450                             const unsigned char *merge,
1451                             int num_base_list,
1452                             const unsigned char **base_list,
1453                             struct commit **result)
1454 {
1455         int clean, index_fd;
1456         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1457         struct commit *head_commit = get_ref(head, o->branch1);
1458         struct commit *next_commit = get_ref(merge, o->branch2);
1459         struct commit_list *ca = NULL;
1460
1461         if (base_list) {
1462                 int i;
1463                 for (i = 0; i < num_base_list; ++i) {
1464                         struct commit *base;
1465                         if (!(base = get_ref(base_list[i], sha1_to_hex(base_list[i]))))
1466                                 return error("Could not parse object '%s'",
1467                                         sha1_to_hex(base_list[i]));
1468                         commit_list_insert(base, &ca);
1469                 }
1470         }
1471
1472         index_fd = hold_locked_index(lock, 1);
1473         clean = merge_recursive(o, head_commit, next_commit, ca,
1474                         result);
1475         if (active_cache_changed &&
1476                         (write_cache(index_fd, active_cache, active_nr) ||
1477                          commit_locked_index(lock)))
1478                 return error("Unable to write index.");
1479
1480         return clean ? 0 : 1;
1481 }
1482
1483 static int merge_recursive_config(const char *var, const char *value, void *cb)
1484 {
1485         struct merge_options *o = cb;
1486         if (!strcasecmp(var, "merge.verbosity")) {
1487                 o->verbosity = git_config_int(var, value);
1488                 return 0;
1489         }
1490         if (!strcasecmp(var, "diff.renamelimit")) {
1491                 o->diff_rename_limit = git_config_int(var, value);
1492                 return 0;
1493         }
1494         if (!strcasecmp(var, "merge.renamelimit")) {
1495                 o->merge_rename_limit = git_config_int(var, value);
1496                 return 0;
1497         }
1498         return git_xmerge_config(var, value, cb);
1499 }
1500
1501 void init_merge_options(struct merge_options *o)
1502 {
1503         memset(o, 0, sizeof(struct merge_options));
1504         o->verbosity = 2;
1505         o->buffer_output = 1;
1506         o->diff_rename_limit = -1;
1507         o->merge_rename_limit = -1;
1508         git_config(merge_recursive_config, o);
1509         if (getenv("GIT_MERGE_VERBOSITY"))
1510                 o->verbosity =
1511                         strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1512         if (o->verbosity >= 5)
1513                 o->buffer_output = 0;
1514         strbuf_init(&o->obuf, 0);
1515         memset(&o->current_file_set, 0, sizeof(struct string_list));
1516         o->current_file_set.strdup_strings = 1;
1517         memset(&o->current_directory_set, 0, sizeof(struct string_list));
1518         o->current_directory_set.strdup_strings = 1;
1519 }