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 enum rename_type {
  67         RENAME_NORMAL = 0,
  68         RENAME_DELETE,
  69         RENAME_ONE_FILE_TO_TWO
  70 };
  71
  72 struct rename_df_conflict_info {
  73         enum rename_type rename_type;
  74         struct diff_filepair *pair1;
  75         struct diff_filepair *pair2;
  76         const char *branch1;
  77         const char *branch2;
  78         struct stage_data *dst_entry1;
  79         struct stage_data *dst_entry2;
  80 };
  81
  82 /*
  83  * Since we want to write the index eventually, we cannot reuse the index
  84  * for these (temporary) data.
  85  */
  86 struct stage_data
  87 {
  88         struct
  89         {
  90                 unsigned mode;
  91                 unsigned char sha[20];
  92         } stages[4];
  93         struct rename_df_conflict_info *rename_df_conflict_info;
  94         unsigned processed:1;
  95 };
  96
  97 static inline void setup_rename_df_conflict_info(enum rename_type rename_type,
  98                                                  struct diff_filepair *pair1,
  99                                                  struct diff_filepair *pair2,
 100                                                  const char *branch1,
 101                                                  const char *branch2,
 102                                                  struct stage_data *dst_entry1,
 103                                                  struct stage_data *dst_entry2)
 104 {
 105         struct rename_df_conflict_info *ci = xcalloc(1, sizeof(struct rename_df_conflict_info));
 106         ci->rename_type = rename_type;
 107         ci->pair1 = pair1;
 108         ci->branch1 = branch1;
 109         ci->branch2 = branch2;
 110
 111         ci->dst_entry1 = dst_entry1;
 112         dst_entry1->rename_df_conflict_info = ci;
 113         dst_entry1->processed = 0;
 114
 115         assert(!pair2 == !dst_entry2);
 116         if (dst_entry2) {
 117                 ci->dst_entry2 = dst_entry2;
 118                 ci->pair2 = pair2;
 119                 dst_entry2->rename_df_conflict_info = ci;
 120                 dst_entry2->processed = 0;
 121         }
 122 }
 123
 124 static int show(struct merge_options *o, int v)
 125 {
 126         return (!o->call_depth && o->verbosity >= v) || o->verbosity >= 5;
 127 }
 128
 129 static void flush_output(struct merge_options *o)
 130 {
 131         if (o->obuf.len) {
 132                 fputs(o->obuf.buf, stdout);
 133                 strbuf_reset(&o->obuf);
 134         }
 135 }
 136
 137 __attribute__((format (printf, 3, 4)))
 138 static void output(struct merge_options *o, int v, const char *fmt, ...)
 139 {
 140         int len;
 141         va_list ap;
 142
 143         if (!show(o, v))
 144                 return;
 145
 146         strbuf_grow(&o->obuf, o->call_depth * 2 + 2);
 147         memset(o->obuf.buf + o->obuf.len, ' ', o->call_depth * 2);
 148         strbuf_setlen(&o->obuf, o->obuf.len + o->call_depth * 2);
 149
 150         va_start(ap, fmt);
 151         len = vsnprintf(o->obuf.buf + o->obuf.len, strbuf_avail(&o->obuf), fmt, ap);
 152         va_end(ap);
 153
 154         if (len < 0)
 155                 len = 0;
 156         if (len >= strbuf_avail(&o->obuf)) {
 157                 strbuf_grow(&o->obuf, len + 2);
 158                 va_start(ap, fmt);
 159                 len = vsnprintf(o->obuf.buf + o->obuf.len, strbuf_avail(&o->obuf), fmt, ap);
 160                 va_end(ap);
 161                 if (len >= strbuf_avail(&o->obuf)) {
 162                         die("this should not happen, your snprintf is broken");
 163                 }
 164         }
 165         strbuf_setlen(&o->obuf, o->obuf.len + len);
 166         strbuf_add(&o->obuf, "\n", 1);
 167         if (!o->buffer_output)
 168                 flush_output(o);
 169 }
 170
 171 static void output_commit_title(struct merge_options *o, struct commit *commit)
 172 {
 173         int i;
 174         flush_output(o);
 175         for (i = o->call_depth; i--;)
 176                 fputs("  ", stdout);
 177         if (commit->util)
 178                 printf("virtual %s\n", (char *)commit->util);
 179         else {
 180                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 181                 if (parse_commit(commit) != 0)
 182                         printf("(bad commit)\n");
 183                 else {
 184                         const char *title;
 185                         int len = find_commit_subject(commit->buffer, &title);
 186                         if (len)
 187                                 printf("%.*s\n", len, title);
 188                 }
 189         }
 190 }
 191
 192 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 193                 const char *path, int stage, int refresh, int options)
 194 {
 195         struct cache_entry *ce;
 196         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 197         if (!ce)
 198                 return error("addinfo_cache failed for path '%s'", path);
 199         return add_cache_entry(ce, options);
 200 }
 201
 202 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 203 {
 204         parse_tree(tree);
 205         init_tree_desc(desc, tree->buffer, tree->size);
 206 }
 207
 208 static int git_merge_trees(int index_only,
 209                            struct tree *common,
 210                            struct tree *head,
 211                            struct tree *merge)
 212 {
 213         int rc;
 214         struct tree_desc t[3];
 215         struct unpack_trees_options opts;
 216
 217         memset(&opts, 0, sizeof(opts));
 218         if (index_only)
 219                 opts.index_only = 1;
 220         else
 221                 opts.update = 1;
 222         opts.merge = 1;
 223         opts.head_idx = 2;
 224         opts.fn = threeway_merge;
 225         opts.src_index = &the_index;
 226         opts.dst_index = &the_index;
 227         setup_unpack_trees_porcelain(&opts, "merge");
 228
 229         init_tree_desc_from_tree(t+0, common);
 230         init_tree_desc_from_tree(t+1, head);
 231         init_tree_desc_from_tree(t+2, merge);
 232
 233         rc = unpack_trees(3, t, &opts);
 234         cache_tree_free(&active_cache_tree);
 235         return rc;
 236 }
 237
 238 struct tree *write_tree_from_memory(struct merge_options *o)
 239 {
 240         struct tree *result = NULL;
 241
 242         if (unmerged_cache()) {
 243                 int i;
 244                 fprintf(stderr, "BUG: There are unmerged index entries:\n");
 245                 for (i = 0; i < active_nr; i++) {
 246                         struct cache_entry *ce = active_cache[i];
 247                         if (ce_stage(ce))
 248                                 fprintf(stderr, "BUG: %d %.*s", ce_stage(ce),
 249                                         (int)ce_namelen(ce), ce->name);
 250                 }
 251                 die("Bug in merge-recursive.c");
 252         }
 253
 254         if (!active_cache_tree)
 255                 active_cache_tree = cache_tree();
 256
 257         if (!cache_tree_fully_valid(active_cache_tree) &&
 258             cache_tree_update(active_cache_tree,
 259                               active_cache, active_nr, 0, 0) < 0)
 260                 die("error building trees");
 261
 262         result = lookup_tree(active_cache_tree->sha1);
 263
 264         return result;
 265 }
 266
 267 static int save_files_dirs(const unsigned char *sha1,
 268                 const char *base, int baselen, const char *path,
 269                 unsigned int mode, int stage, void *context)
 270 {
 271         int len = strlen(path);
 272         char *newpath = xmalloc(baselen + len + 1);
 273         struct merge_options *o = context;
 274
 275         memcpy(newpath, base, baselen);
 276         memcpy(newpath + baselen, path, len);
 277         newpath[baselen + len] = '\0';
 278
 279         if (S_ISDIR(mode))
 280                 string_list_insert(&o->current_directory_set, newpath);
 281         else
 282                 string_list_insert(&o->current_file_set, newpath);
 283         free(newpath);
 284
 285         return (S_ISDIR(mode) ? READ_TREE_RECURSIVE : 0);
 286 }
 287
 288 static int get_files_dirs(struct merge_options *o, struct tree *tree)
 289 {
 290         int n;
 291         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs, o))
 292                 return 0;
 293         n = o->current_file_set.nr + o->current_directory_set.nr;
 294         return n;
 295 }
 296
 297 /*
 298  * Returns an index_entry instance which doesn't have to correspond to
 299  * a real cache entry in Git's index.
 300  */
 301 static struct stage_data *insert_stage_data(const char *path,
 302                 struct tree *o, struct tree *a, struct tree *b,
 303                 struct string_list *entries)
 304 {
 305         struct string_list_item *item;
 306         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 307         get_tree_entry(o->object.sha1, path,
 308                         e->stages[1].sha, &e->stages[1].mode);
 309         get_tree_entry(a->object.sha1, path,
 310                         e->stages[2].sha, &e->stages[2].mode);
 311         get_tree_entry(b->object.sha1, path,
 312                         e->stages[3].sha, &e->stages[3].mode);
 313         item = string_list_insert(entries, path);
 314         item->util = e;
 315         return e;
 316 }
 317
 318 /*
 319  * Create a dictionary mapping file names to stage_data objects. The
 320  * dictionary contains one entry for every path with a non-zero stage entry.
 321  */
 322 static struct string_list *get_unmerged(void)
 323 {
 324         struct string_list *unmerged = xcalloc(1, sizeof(struct string_list));
 325         int i;
 326
 327         unmerged->strdup_strings = 1;
 328
 329         for (i = 0; i < active_nr; i++) {
 330                 struct string_list_item *item;
 331                 struct stage_data *e;
 332                 struct cache_entry *ce = active_cache[i];
 333                 if (!ce_stage(ce))
 334                         continue;
 335
 336                 item = string_list_lookup(unmerged, ce->name);
 337                 if (!item) {
 338                         item = string_list_insert(unmerged, ce->name);
 339                         item->util = xcalloc(1, sizeof(struct stage_data));
 340                 }
 341                 e = item->util;
 342                 e->stages[ce_stage(ce)].mode = ce->ce_mode;
 343                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 344         }
 345
 346         return unmerged;
 347 }
 348
 349 static void make_room_for_directories_of_df_conflicts(struct merge_options *o,
 350                                                       struct string_list *entries)
 351 {
 352         /* If there are D/F conflicts, and the paths currently exist
 353          * in the working copy as a file, we want to remove them to
 354          * make room for the corresponding directory.  Such paths will
 355          * later be processed in process_df_entry() at the end.  If
 356          * the corresponding directory ends up being removed by the
 357          * merge, then the file will be reinstated at that time;
 358          * otherwise, if the file is not supposed to be removed by the
 359          * merge, the contents of the file will be placed in another
 360          * unique filename.
 361          *
 362          * NOTE: This function relies on the fact that entries for a
 363          * D/F conflict will appear adjacent in the index, with the
 364          * entries for the file appearing before entries for paths
 365          * below the corresponding directory.
 366          */
 367         const char *last_file = NULL;
 368         int last_len = 0;
 369         struct stage_data *last_e;
 370         int i;
 371
 372         for (i = 0; i < entries->nr; i++) {
 373                 const char *path = entries->items[i].string;
 374                 int len = strlen(path);
 375                 struct stage_data *e = entries->items[i].util;
 376
 377                 /*
 378                  * Check if last_file & path correspond to a D/F conflict;
 379                  * i.e. whether path is last_file+'/'+<something>.
 380                  * If so, remove last_file to make room for path and friends.
 381                  */
 382                 if (last_file &&
 383                     len > last_len &&
 384                     memcmp(path, last_file, last_len) == 0 &&
 385                     path[last_len] == '/') {
 386                         output(o, 3, "Removing %s to make room for subdirectory; may re-add later.", last_file);
 387                         unlink(last_file);
 388                 }
 389
 390                 /*
 391                  * Determine whether path could exist as a file in the
 392                  * working directory as a possible D/F conflict.  This
 393                  * will only occur when it exists in stage 2 as a
 394                  * file.
 395                  */
 396                 if (S_ISREG(e->stages[2].mode) || S_ISLNK(e->stages[2].mode)) {
 397                         last_file = path;
 398                         last_len = len;
 399                         last_e = e;
 400                 } else {
 401                         last_file = NULL;
 402                 }
 403         }
 404 }
 405
 406 struct rename
 407 {
 408         struct diff_filepair *pair;
 409         struct stage_data *src_entry;
 410         struct stage_data *dst_entry;
 411         unsigned processed:1;
 412 };
 413
 414 /*
 415  * Get information of all renames which occurred between 'o_tree' and
 416  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 417  * 'b_tree') to be able to associate the correct cache entries with
 418  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 419  */
 420 static struct string_list *get_renames(struct merge_options *o,
 421                                        struct tree *tree,
 422                                        struct tree *o_tree,
 423                                        struct tree *a_tree,
 424                                        struct tree *b_tree,
 425                                        struct string_list *entries)
 426 {
 427         int i;
 428         struct string_list *renames;
 429         struct diff_options opts;
 430
 431         renames = xcalloc(1, sizeof(struct string_list));
 432         diff_setup(&opts);
 433         DIFF_OPT_SET(&opts, RECURSIVE);
 434         opts.detect_rename = DIFF_DETECT_RENAME;
 435         opts.rename_limit = o->merge_rename_limit >= 0 ? o->merge_rename_limit :
 436                             o->diff_rename_limit >= 0 ? o->diff_rename_limit :
 437                             500;
 438         opts.rename_score = o->rename_score;
 439         opts.warn_on_too_large_rename = 1;
 440         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 441         if (diff_setup_done(&opts) < 0)
 442                 die("diff setup failed");
 443         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 444         diffcore_std(&opts);
 445         for (i = 0; i < diff_queued_diff.nr; ++i) {
 446                 struct string_list_item *item;
 447                 struct rename *re;
 448                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 449                 if (pair->status != 'R') {
 450                         diff_free_filepair(pair);
 451                         continue;
 452                 }
 453                 re = xmalloc(sizeof(*re));
 454                 re->processed = 0;
 455                 re->pair = pair;
 456                 item = string_list_lookup(entries, re->pair->one->path);
 457                 if (!item)
 458                         re->src_entry = insert_stage_data(re->pair->one->path,
 459                                         o_tree, a_tree, b_tree, entries);
 460                 else
 461                         re->src_entry = item->util;
 462
 463                 item = string_list_lookup(entries, re->pair->two->path);
 464                 if (!item)
 465                         re->dst_entry = insert_stage_data(re->pair->two->path,
 466                                         o_tree, a_tree, b_tree, entries);
 467                 else
 468                         re->dst_entry = item->util;
 469                 item = string_list_insert(renames, pair->one->path);
 470                 item->util = re;
 471         }
 472         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 473         diff_queued_diff.nr = 0;
 474         diff_flush(&opts);
 475         return renames;
 476 }
 477
 478 static int update_stages_options(const char *path, struct diff_filespec *o,
 479                          struct diff_filespec *a, struct diff_filespec *b,
 480                          int clear, int options)
 481 {
 482         if (clear)
 483                 if (remove_file_from_cache(path))
 484                         return -1;
 485         if (o)
 486                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 487                         return -1;
 488         if (a)
 489                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 490                         return -1;
 491         if (b)
 492                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 493                         return -1;
 494         return 0;
 495 }
 496
 497 static int update_stages(const char *path, struct diff_filespec *o,
 498                          struct diff_filespec *a, struct diff_filespec *b,
 499                          int clear)
 500 {
 501         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 502         return update_stages_options(path, o, a, b, clear, options);
 503 }
 504
 505 static int update_stages_and_entry(const char *path,
 506                                    struct stage_data *entry,
 507                                    struct diff_filespec *o,
 508                                    struct diff_filespec *a,
 509                                    struct diff_filespec *b,
 510                                    int clear)
 511 {
 512         int options;
 513
 514         entry->processed = 0;
 515         entry->stages[1].mode = o->mode;
 516         entry->stages[2].mode = a->mode;
 517         entry->stages[3].mode = b->mode;
 518         hashcpy(entry->stages[1].sha, o->sha1);
 519         hashcpy(entry->stages[2].sha, a->sha1);
 520         hashcpy(entry->stages[3].sha, b->sha1);
 521         options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_SKIP_DFCHECK;
 522         return update_stages_options(path, o, a, b, clear, options);
 523 }
 524
 525 static int remove_file(struct merge_options *o, int clean,
 526                        const char *path, int no_wd)
 527 {
 528         int update_cache = o->call_depth || clean;
 529         int update_working_directory = !o->call_depth && !no_wd;
 530
 531         if (update_cache) {
 532                 if (remove_file_from_cache(path))
 533                         return -1;
 534         }
 535         if (update_working_directory) {
 536                 if (remove_path(path))
 537                         return -1;
 538         }
 539         return 0;
 540 }
 541
 542 static char *unique_path(struct merge_options *o, const char *path, const char *branch)
 543 {
 544         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 545         int suffix = 0;
 546         struct stat st;
 547         char *p = newpath + strlen(path);
 548         strcpy(newpath, path);
 549         *(p++) = '~';
 550         strcpy(p, branch);
 551         for (; *p; ++p)
 552                 if ('/' == *p)
 553                         *p = '_';
 554         while (string_list_has_string(&o->current_file_set, newpath) ||
 555                string_list_has_string(&o->current_directory_set, newpath) ||
 556                lstat(newpath, &st) == 0)
 557                 sprintf(p, "_%d", suffix++);
 558
 559         string_list_insert(&o->current_file_set, newpath);
 560         return newpath;
 561 }
 562
 563 static void flush_buffer(int fd, const char *buf, unsigned long size)
 564 {
 565         while (size > 0) {
 566                 long ret = write_in_full(fd, buf, size);
 567                 if (ret < 0) {
 568                         /* Ignore epipe */
 569                         if (errno == EPIPE)
 570                                 break;
 571                         die_errno("merge-recursive");
 572                 } else if (!ret) {
 573                         die("merge-recursive: disk full?");
 574                 }
 575                 size -= ret;
 576                 buf += ret;
 577         }
 578 }
 579
 580 static int would_lose_untracked(const char *path)
 581 {
 582         int pos = cache_name_pos(path, strlen(path));
 583
 584         if (pos < 0)
 585                 pos = -1 - pos;
 586         while (pos < active_nr &&
 587                !strcmp(path, active_cache[pos]->name)) {
 588                 /*
 589                  * If stage #0, it is definitely tracked.
 590                  * If it has stage #2 then it was tracked
 591                  * before this merge started.  All other
 592                  * cases the path was not tracked.
 593                  */
 594                 switch (ce_stage(active_cache[pos])) {
 595                 case 0:
 596                 case 2:
 597                         return 0;
 598                 }
 599                 pos++;
 600         }
 601         return file_exists(path);
 602 }
 603
 604 static int make_room_for_path(const char *path)
 605 {
 606         int status;
 607         const char *msg = "failed to create path '%s'%s";
 608
 609         status = safe_create_leading_directories_const(path);
 610         if (status) {
 611                 if (status == -3) {
 612                         /* something else exists */
 613                         error(msg, path, ": perhaps a D/F conflict?");
 614                         return -1;
 615                 }
 616                 die(msg, path, "");
 617         }
 618
 619         /*
 620          * Do not unlink a file in the work tree if we are not
 621          * tracking it.
 622          */
 623         if (would_lose_untracked(path))
 624                 return error("refusing to lose untracked file at '%s'",
 625                              path);
 626
 627         /* Successful unlink is good.. */
 628         if (!unlink(path))
 629                 return 0;
 630         /* .. and so is no existing file */
 631         if (errno == ENOENT)
 632                 return 0;
 633         /* .. but not some other error (who really cares what?) */
 634         return error(msg, path, ": perhaps a D/F conflict?");
 635 }
 636
 637 static void update_file_flags(struct merge_options *o,
 638                               const unsigned char *sha,
 639                               unsigned mode,
 640                               const char *path,
 641                               int update_cache,
 642                               int update_wd)
 643 {
 644         if (o->call_depth)
 645                 update_wd = 0;
 646
 647         if (update_wd) {
 648                 enum object_type type;
 649                 void *buf;
 650                 unsigned long size;
 651
 652                 if (S_ISGITLINK(mode)) {
 653                         /*
 654                          * We may later decide to recursively descend into
 655                          * the submodule directory and update its index
 656                          * and/or work tree, but we do not do that now.
 657                          */
 658                         update_wd = 0;
 659                         goto update_index;
 660                 }
 661
 662                 buf = read_sha1_file(sha, &type, &size);
 663                 if (!buf)
 664                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 665                 if (type != OBJ_BLOB)
 666                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 667                 if (S_ISREG(mode)) {
 668                         struct strbuf strbuf = STRBUF_INIT;
 669                         if (convert_to_working_tree(path, buf, size, &strbuf)) {
 670                                 free(buf);
 671                                 size = strbuf.len;
 672                                 buf = strbuf_detach(&strbuf, NULL);
 673                         }
 674                 }
 675
 676                 if (make_room_for_path(path) < 0) {
 677                         update_wd = 0;
 678                         free(buf);
 679                         goto update_index;
 680                 }
 681                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 682                         int fd;
 683                         if (mode & 0100)
 684                                 mode = 0777;
 685                         else
 686                                 mode = 0666;
 687                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 688                         if (fd < 0)
 689                                 die_errno("failed to open '%s'", path);
 690                         flush_buffer(fd, buf, size);
 691                         close(fd);
 692                 } else if (S_ISLNK(mode)) {
 693                         char *lnk = xmemdupz(buf, size);
 694                         safe_create_leading_directories_const(path);
 695                         unlink(path);
 696                         if (symlink(lnk, path))
 697                                 die_errno("failed to symlink '%s'", path);
 698                         free(lnk);
 699                 } else
 700                         die("do not know what to do with %06o %s '%s'",
 701                             mode, sha1_to_hex(sha), path);
 702                 free(buf);
 703         }
 704  update_index:
 705         if (update_cache)
 706                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 707 }
 708
 709 static void update_file(struct merge_options *o,
 710                         int clean,
 711                         const unsigned char *sha,
 712                         unsigned mode,
 713                         const char *path)
 714 {
 715         update_file_flags(o, sha, mode, path, o->call_depth || clean, !o->call_depth);
 716 }
 717
 718 /* Low level file merging, update and removal */
 719
 720 struct merge_file_info
 721 {
 722         unsigned char sha[20];
 723         unsigned mode;
 724         unsigned clean:1,
 725                  merge:1;
 726 };
 727
 728 static int merge_3way(struct merge_options *o,
 729                       mmbuffer_t *result_buf,
 730                       struct diff_filespec *one,
 731                       struct diff_filespec *a,
 732                       struct diff_filespec *b,
 733                       const char *branch1,
 734                       const char *branch2)
 735 {
 736         mmfile_t orig, src1, src2;
 737         struct ll_merge_options ll_opts = {0};
 738         char *base_name, *name1, *name2;
 739         int merge_status;
 740
 741         ll_opts.renormalize = o->renormalize;
 742         ll_opts.xdl_opts = o->xdl_opts;
 743
 744         if (o->call_depth) {
 745                 ll_opts.virtual_ancestor = 1;
 746                 ll_opts.variant = 0;
 747         } else {
 748                 switch (o->recursive_variant) {
 749                 case MERGE_RECURSIVE_OURS:
 750                         ll_opts.variant = XDL_MERGE_FAVOR_OURS;
 751                         break;
 752                 case MERGE_RECURSIVE_THEIRS:
 753                         ll_opts.variant = XDL_MERGE_FAVOR_THEIRS;
 754                         break;
 755                 default:
 756                         ll_opts.variant = 0;
 757                         break;
 758                 }
 759         }
 760
 761         if (strcmp(a->path, b->path) ||
 762             (o->ancestor != NULL && strcmp(a->path, one->path) != 0)) {
 763                 base_name = o->ancestor == NULL ? NULL :
 764                         xstrdup(mkpath("%s:%s", o->ancestor, one->path));
 765                 name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 766                 name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 767         } else {
 768                 base_name = o->ancestor == NULL ? NULL :
 769                         xstrdup(mkpath("%s", o->ancestor));
 770                 name1 = xstrdup(mkpath("%s", branch1));
 771                 name2 = xstrdup(mkpath("%s", branch2));
 772         }
 773
 774         read_mmblob(&orig, one->sha1);
 775         read_mmblob(&src1, a->sha1);
 776         read_mmblob(&src2, b->sha1);
 777
 778         merge_status = ll_merge(result_buf, a->path, &orig, base_name,
 779                                 &src1, name1, &src2, name2, &ll_opts);
 780
 781         free(name1);
 782         free(name2);
 783         free(orig.ptr);
 784         free(src1.ptr);
 785         free(src2.ptr);
 786         return merge_status;
 787 }
 788
 789 static struct merge_file_info merge_file(struct merge_options *o,
 790                                          struct diff_filespec *one,
 791                                          struct diff_filespec *a,
 792                                          struct diff_filespec *b,
 793                                          const char *branch1,
 794                                          const char *branch2)
 795 {
 796         struct merge_file_info result;
 797         result.merge = 0;
 798         result.clean = 1;
 799
 800         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 801                 result.clean = 0;
 802                 if (S_ISREG(a->mode)) {
 803                         result.mode = a->mode;
 804                         hashcpy(result.sha, a->sha1);
 805                 } else {
 806                         result.mode = b->mode;
 807                         hashcpy(result.sha, b->sha1);
 808                 }
 809         } else {
 810                 if (!sha_eq(a->sha1, one->sha1) && !sha_eq(b->sha1, one->sha1))
 811                         result.merge = 1;
 812
 813                 /*
 814                  * Merge modes
 815                  */
 816                 if (a->mode == b->mode || a->mode == one->mode)
 817                         result.mode = b->mode;
 818                 else {
 819                         result.mode = a->mode;
 820                         if (b->mode != one->mode) {
 821                                 result.clean = 0;
 822                                 result.merge = 1;
 823                         }
 824                 }
 825
 826                 if (sha_eq(a->sha1, b->sha1) || sha_eq(a->sha1, one->sha1))
 827                         hashcpy(result.sha, b->sha1);
 828                 else if (sha_eq(b->sha1, one->sha1))
 829                         hashcpy(result.sha, a->sha1);
 830                 else if (S_ISREG(a->mode)) {
 831                         mmbuffer_t result_buf;
 832                         int merge_status;
 833
 834                         merge_status = merge_3way(o, &result_buf, one, a, b,
 835                                                   branch1, branch2);
 836
 837                         if ((merge_status < 0) || !result_buf.ptr)
 838                                 die("Failed to execute internal merge");
 839
 840                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 841                                             blob_type, result.sha))
 842                                 die("Unable to add %s to database",
 843                                     a->path);
 844
 845                         free(result_buf.ptr);
 846                         result.clean = (merge_status == 0);
 847                 } else if (S_ISGITLINK(a->mode)) {
 848                         result.clean = merge_submodule(result.sha, one->path, one->sha1,
 849                                                        a->sha1, b->sha1);
 850                 } else if (S_ISLNK(a->mode)) {
 851                         hashcpy(result.sha, a->sha1);
 852
 853                         if (!sha_eq(a->sha1, b->sha1))
 854                                 result.clean = 0;
 855                 } else {
 856                         die("unsupported object type in the tree");
 857                 }
 858         }
 859
 860         return result;
 861 }
 862
 863 static void conflict_rename_delete(struct merge_options *o,
 864                                    struct diff_filepair *pair,
 865                                    const char *rename_branch,
 866                                    const char *other_branch)
 867 {
 868         char *dest_name = pair->two->path;
 869         int df_conflict = 0;
 870         struct stat st;
 871
 872         output(o, 1, "CONFLICT (rename/delete): Rename %s->%s in %s "
 873                "and deleted in %s",
 874                pair->one->path, pair->two->path, rename_branch,
 875                other_branch);
 876         if (!o->call_depth)
 877                 update_stages(dest_name, NULL,
 878                               rename_branch == o->branch1 ? pair->two : NULL,
 879                               rename_branch == o->branch1 ? NULL : pair->two,
 880                               1);
 881         if (lstat(dest_name, &st) == 0 && S_ISDIR(st.st_mode)) {
 882                 dest_name = unique_path(o, dest_name, rename_branch);
 883                 df_conflict = 1;
 884         }
 885         update_file(o, 0, pair->two->sha1, pair->two->mode, dest_name);
 886         if (df_conflict)
 887                 free(dest_name);
 888 }
 889
 890 static void conflict_rename_rename_1to2(struct merge_options *o,
 891                                         struct diff_filepair *pair1,
 892                                         const char *branch1,
 893                                         struct diff_filepair *pair2,
 894                                         const char *branch2)
 895 {
 896         /* One file was renamed in both branches, but to different names. */
 897         char *del[2];
 898         int delp = 0;
 899         const char *ren1_dst = pair1->two->path;
 900         const char *ren2_dst = pair2->two->path;
 901         const char *dst_name1 = ren1_dst;
 902         const char *dst_name2 = ren2_dst;
 903         struct stat st;
 904         if (lstat(ren1_dst, &st) == 0 && S_ISDIR(st.st_mode)) {
 905                 dst_name1 = del[delp++] = unique_path(o, ren1_dst, branch1);
 906                 output(o, 1, "%s is a directory in %s adding as %s instead",
 907                        ren1_dst, branch2, dst_name1);
 908         }
 909         if (lstat(ren2_dst, &st) == 0 && S_ISDIR(st.st_mode)) {
 910                 dst_name2 = del[delp++] = unique_path(o, ren2_dst, branch2);
 911                 output(o, 1, "%s is a directory in %s adding as %s instead",
 912                        ren2_dst, branch1, dst_name2);
 913         }
 914         if (o->call_depth) {
 915                 remove_file_from_cache(dst_name1);
 916                 remove_file_from_cache(dst_name2);
 917                 /*
 918                  * Uncomment to leave the conflicting names in the resulting tree
 919                  *
 920                  * update_file(o, 0, pair1->two->sha1, pair1->two->mode, dst_name1);
 921                  * update_file(o, 0, pair2->two->sha1, pair2->two->mode, dst_name2);
 922                  */
 923         } else {
 924                 update_stages(ren1_dst, NULL, pair1->two, NULL, 1);
 925                 update_stages(ren2_dst, NULL, NULL, pair2->two, 1);
 926
 927                 update_file(o, 0, pair1->two->sha1, pair1->two->mode, dst_name1);
 928                 update_file(o, 0, pair2->two->sha1, pair2->two->mode, dst_name2);
 929         }
 930         while (delp--)
 931                 free(del[delp]);
 932 }
 933
 934 static void conflict_rename_rename_2to1(struct merge_options *o,
 935                                         struct rename *ren1,
 936                                         const char *branch1,
 937                                         struct rename *ren2,
 938                                         const char *branch2)
 939 {
 940         /* Two files were renamed to the same thing. */
 941         char *new_path1 = unique_path(o, ren1->pair->two->path, branch1);
 942         char *new_path2 = unique_path(o, ren2->pair->two->path, branch2);
 943         output(o, 1, "Renaming %s to %s and %s to %s instead",
 944                ren1->pair->one->path, new_path1,
 945                ren2->pair->one->path, new_path2);
 946         remove_file(o, 0, ren1->pair->two->path, 0);
 947         update_file(o, 0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 948         update_file(o, 0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 949         free(new_path2);
 950         free(new_path1);
 951 }
 952
 953 static int process_renames(struct merge_options *o,
 954                            struct string_list *a_renames,
 955                            struct string_list *b_renames)
 956 {
 957         int clean_merge = 1, i, j;
 958         struct string_list a_by_dst = STRING_LIST_INIT_NODUP;
 959         struct string_list b_by_dst = STRING_LIST_INIT_NODUP;
 960         const struct rename *sre;
 961
 962         for (i = 0; i < a_renames->nr; i++) {
 963                 sre = a_renames->items[i].util;
 964                 string_list_insert(&a_by_dst, sre->pair->two->path)->util
 965                         = sre->dst_entry;
 966         }
 967         for (i = 0; i < b_renames->nr; i++) {
 968                 sre = b_renames->items[i].util;
 969                 string_list_insert(&b_by_dst, sre->pair->two->path)->util
 970                         = sre->dst_entry;
 971         }
 972
 973         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 974                 char *src;
 975                 struct string_list *renames1, *renames2Dst;
 976                 struct rename *ren1 = NULL, *ren2 = NULL;
 977                 const char *branch1, *branch2;
 978                 const char *ren1_src, *ren1_dst;
 979
 980                 if (i >= a_renames->nr) {
 981                         ren2 = b_renames->items[j++].util;
 982                 } else if (j >= b_renames->nr) {
 983                         ren1 = a_renames->items[i++].util;
 984                 } else {
 985                         int compare = strcmp(a_renames->items[i].string,
 986                                              b_renames->items[j].string);
 987                         if (compare <= 0)
 988                                 ren1 = a_renames->items[i++].util;
 989                         if (compare >= 0)
 990                                 ren2 = b_renames->items[j++].util;
 991                 }
 992
 993                 /* TODO: refactor, so that 1/2 are not needed */
 994                 if (ren1) {
 995                         renames1 = a_renames;
 996                         renames2Dst = &b_by_dst;
 997                         branch1 = o->branch1;
 998                         branch2 = o->branch2;
 999                 } else {
1000                         struct rename *tmp;
1001                         renames1 = b_renames;
1002                         renames2Dst = &a_by_dst;
1003                         branch1 = o->branch2;
1004                         branch2 = o->branch1;
1005                         tmp = ren2;
1006                         ren2 = ren1;
1007                         ren1 = tmp;
1008                 }
1009                 src = ren1->pair->one->path;
1010
1011                 ren1->dst_entry->processed = 1;
1012                 ren1->src_entry->processed = 1;
1013
1014                 if (ren1->processed)
1015                         continue;
1016                 ren1->processed = 1;
1017
1018                 ren1_src = ren1->pair->one->path;
1019                 ren1_dst = ren1->pair->two->path;
1020
1021                 if (ren2) {
1022                         const char *ren2_src = ren2->pair->one->path;
1023                         const char *ren2_dst = ren2->pair->two->path;
1024                         /* Renamed in 1 and renamed in 2 */
1025                         if (strcmp(ren1_src, ren2_src) != 0)
1026                                 die("ren1.src != ren2.src");
1027                         ren2->dst_entry->processed = 1;
1028                         ren2->processed = 1;
1029                         if (strcmp(ren1_dst, ren2_dst) != 0) {
1030                                 setup_rename_df_conflict_info(RENAME_ONE_FILE_TO_TWO,
1031                                                               ren1->pair,
1032                                                               ren2->pair,
1033                                                               branch1,
1034                                                               branch2,
1035                                                               ren1->dst_entry,
1036                                                               ren2->dst_entry);
1037                         } else {
1038                                 remove_file(o, 1, ren1_src, 1);
1039                                 update_stages_and_entry(ren1_dst,
1040                                                         ren1->dst_entry,
1041                                                         ren1->pair->one,
1042                                                         ren1->pair->two,
1043                                                         ren2->pair->two,
1044                                                         1 /* clear */);
1045                         }
1046                 } else {
1047                         /* Renamed in 1, maybe changed in 2 */
1048                         struct string_list_item *item;
1049                         /* we only use sha1 and mode of these */
1050                         struct diff_filespec src_other, dst_other;
1051                         int try_merge;
1052
1053                         /*
1054                          * unpack_trees loads entries from common-commit
1055                          * into stage 1, from head-commit into stage 2, and
1056                          * from merge-commit into stage 3.  We keep track
1057                          * of which side corresponds to the rename.
1058                          */
1059                         int renamed_stage = a_renames == renames1 ? 2 : 3;
1060                         int other_stage =   a_renames == renames1 ? 3 : 2;
1061
1062                         remove_file(o, 1, ren1_src, o->call_depth || renamed_stage == 2);
1063
1064                         hashcpy(src_other.sha1, ren1->src_entry->stages[other_stage].sha);
1065                         src_other.mode = ren1->src_entry->stages[other_stage].mode;
1066                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[other_stage].sha);
1067                         dst_other.mode = ren1->dst_entry->stages[other_stage].mode;
1068                         try_merge = 0;
1069
1070                         if (sha_eq(src_other.sha1, null_sha1)) {
1071                                 if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
1072                                         ren1->dst_entry->processed = 0;
1073                                         setup_rename_df_conflict_info(RENAME_DELETE,
1074                                                                       ren1->pair,
1075                                                                       NULL,
1076                                                                       branch1,
1077                                                                       branch2,
1078                                                                       ren1->dst_entry,
1079                                                                       NULL);
1080                                 } else {
1081                                         clean_merge = 0;
1082                                         conflict_rename_delete(o, ren1->pair, branch1, branch2);
1083                                 }
1084                         } else if ((dst_other.mode == ren1->pair->two->mode) &&
1085                                    sha_eq(dst_other.sha1, ren1->pair->two->sha1)) {
1086                                 /* Added file on the other side
1087                                    identical to the file being
1088                                    renamed: clean merge */
1089                                 update_file(o, 1, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
1090                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
1091                                 const char *new_path;
1092                                 clean_merge = 0;
1093                                 try_merge = 1;
1094                                 output(o, 1, "CONFLICT (rename/add): Rename %s->%s in %s. "
1095                                        "%s added in %s",
1096                                        ren1_src, ren1_dst, branch1,
1097                                        ren1_dst, branch2);
1098                                 if (o->call_depth) {
1099                                         struct merge_file_info mfi;
1100                                         struct diff_filespec one, a, b;
1101
1102                                         one.path = a.path = b.path =
1103                                                 (char *)ren1_dst;
1104                                         hashcpy(one.sha1, null_sha1);
1105                                         one.mode = 0;
1106                                         hashcpy(a.sha1, ren1->pair->two->sha1);
1107                                         a.mode = ren1->pair->two->mode;
1108                                         hashcpy(b.sha1, dst_other.sha1);
1109                                         b.mode = dst_other.mode;
1110                                         mfi = merge_file(o, &one, &a, &b,
1111                                                          branch1,
1112                                                          branch2);
1113                                         output(o, 1, "Adding merged %s", ren1_dst);
1114                                         update_file(o, 0,
1115                                                     mfi.sha,
1116                                                     mfi.mode,
1117                                                     ren1_dst);
1118                                         try_merge = 0;
1119                                 } else {
1120                                         new_path = unique_path(o, ren1_dst, branch2);
1121                                         output(o, 1, "Adding as %s instead", new_path);
1122                                         update_file(o, 0, dst_other.sha1, dst_other.mode, new_path);
1123                                 }
1124                         } else if ((item = string_list_lookup(renames2Dst, ren1_dst))) {
1125                                 ren2 = item->util;
1126                                 clean_merge = 0;
1127                                 ren2->processed = 1;
1128                                 output(o, 1, "CONFLICT (rename/rename): "
1129                                        "Rename %s->%s in %s. "
1130                                        "Rename %s->%s in %s",
1131                                        ren1_src, ren1_dst, branch1,
1132                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
1133                                 conflict_rename_rename_2to1(o, ren1, branch1, ren2, branch2);
1134                         } else
1135                                 try_merge = 1;
1136
1137                         if (try_merge) {
1138                                 struct diff_filespec *one, *a, *b;
1139                                 src_other.path = (char *)ren1_src;
1140
1141                                 one = ren1->pair->one;
1142                                 if (a_renames == renames1) {
1143                                         a = ren1->pair->two;
1144                                         b = &src_other;
1145                                 } else {
1146                                         b = ren1->pair->two;
1147                                         a = &src_other;
1148                                 }
1149                                 update_stages_and_entry(ren1_dst, ren1->dst_entry, one, a, b, 1);
1150                                 if (string_list_has_string(&o->current_directory_set, ren1_dst)) {
1151                                         setup_rename_df_conflict_info(RENAME_NORMAL,
1152                                                                       ren1->pair,
1153                                                                       NULL,
1154                                                                       branch1,
1155                                                                       NULL,
1156                                                                       ren1->dst_entry,
1157                                                                       NULL);
1158                                 }
1159                         }
1160                 }
1161         }
1162         string_list_clear(&a_by_dst, 0);
1163         string_list_clear(&b_by_dst, 0);
1164
1165         return clean_merge;
1166 }
1167
1168 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1169 {
1170         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1171 }
1172
1173 static int read_sha1_strbuf(const unsigned char *sha1, struct strbuf *dst)
1174 {
1175         void *buf;
1176         enum object_type type;
1177         unsigned long size;
1178         buf = read_sha1_file(sha1, &type, &size);
1179         if (!buf)
1180                 return error("cannot read object %s", sha1_to_hex(sha1));
1181         if (type != OBJ_BLOB) {
1182                 free(buf);
1183                 return error("object %s is not a blob", sha1_to_hex(sha1));
1184         }
1185         strbuf_attach(dst, buf, size, size + 1);
1186         return 0;
1187 }
1188
1189 static int blob_unchanged(const unsigned char *o_sha,
1190                           const unsigned char *a_sha,
1191                           int renormalize, const char *path)
1192 {
1193         struct strbuf o = STRBUF_INIT;
1194         struct strbuf a = STRBUF_INIT;
1195         int ret = 0; /* assume changed for safety */
1196
1197         if (sha_eq(o_sha, a_sha))
1198                 return 1;
1199         if (!renormalize)
1200                 return 0;
1201
1202         assert(o_sha && a_sha);
1203         if (read_sha1_strbuf(o_sha, &o) || read_sha1_strbuf(a_sha, &a))
1204                 goto error_return;
1205         /*
1206          * Note: binary | is used so that both renormalizations are
1207          * performed.  Comparison can be skipped if both files are
1208          * unchanged since their sha1s have already been compared.
1209          */
1210         if (renormalize_buffer(path, o.buf, o.len, &o) |
1211             renormalize_buffer(path, a.buf, o.len, &a))
1212                 ret = (o.len == a.len && !memcmp(o.buf, a.buf, o.len));
1213
1214 error_return:
1215         strbuf_release(&o);
1216         strbuf_release(&a);
1217         return ret;
1218 }
1219
1220 static void handle_delete_modify(struct merge_options *o,
1221                                  const char *path,
1222                                  const char *new_path,
1223                                  unsigned char *a_sha, int a_mode,
1224                                  unsigned char *b_sha, int b_mode)
1225 {
1226         if (!a_sha) {
1227                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1228                        "and modified in %s. Version %s of %s left in tree%s%s.",
1229                        path, o->branch1,
1230                        o->branch2, o->branch2, path,
1231                        path == new_path ? "" : " at ",
1232                        path == new_path ? "" : new_path);
1233                 update_file(o, 0, b_sha, b_mode, new_path);
1234         } else {
1235                 output(o, 1, "CONFLICT (delete/modify): %s deleted in %s "
1236                        "and modified in %s. Version %s of %s left in tree%s%s.",
1237                        path, o->branch2,
1238                        o->branch1, o->branch1, path,
1239                        path == new_path ? "" : " at ",
1240                        path == new_path ? "" : new_path);
1241                 update_file(o, 0, a_sha, a_mode, new_path);
1242         }
1243 }
1244
1245 static int merge_content(struct merge_options *o,
1246                          const char *path,
1247                          unsigned char *o_sha, int o_mode,
1248                          unsigned char *a_sha, int a_mode,
1249                          unsigned char *b_sha, int b_mode,
1250                          const char *df_rename_conflict_branch)
1251 {
1252         const char *reason = "content";
1253         struct merge_file_info mfi;
1254         struct diff_filespec one, a, b;
1255         struct stat st;
1256         unsigned df_conflict_remains = 0;
1257
1258         if (!o_sha) {
1259                 reason = "add/add";
1260                 o_sha = (unsigned char *)null_sha1;
1261         }
1262         one.path = a.path = b.path = (char *)path;
1263         hashcpy(one.sha1, o_sha);
1264         one.mode = o_mode;
1265         hashcpy(a.sha1, a_sha);
1266         a.mode = a_mode;
1267         hashcpy(b.sha1, b_sha);
1268         b.mode = b_mode;
1269
1270         mfi = merge_file(o, &one, &a, &b, o->branch1, o->branch2);
1271         if (df_rename_conflict_branch &&
1272             lstat(path, &st) == 0 && S_ISDIR(st.st_mode)) {
1273                 df_conflict_remains = 1;
1274         }
1275
1276         if (mfi.clean && !df_conflict_remains &&
1277             sha_eq(mfi.sha, a_sha) && mfi.mode == a.mode)
1278                 output(o, 3, "Skipped %s (merged same as existing)", path);
1279         else
1280                 output(o, 2, "Auto-merging %s", path);
1281
1282         if (!mfi.clean) {
1283                 if (S_ISGITLINK(mfi.mode))
1284                         reason = "submodule";
1285                 output(o, 1, "CONFLICT (%s): Merge conflict in %s",
1286                                 reason, path);
1287         }
1288
1289         if (df_conflict_remains) {
1290                 const char *new_path;
1291                 update_file_flags(o, mfi.sha, mfi.mode, path,
1292                                   o->call_depth || mfi.clean, 0);
1293                 new_path = unique_path(o, path, df_rename_conflict_branch);
1294                 mfi.clean = 0;
1295                 output(o, 1, "Adding as %s instead", new_path);
1296                 update_file_flags(o, mfi.sha, mfi.mode, new_path, 0, 1);
1297         } else {
1298                 update_file(o, mfi.clean, mfi.sha, mfi.mode, path);
1299         }
1300         return mfi.clean;
1301
1302 }
1303
1304 /* Per entry merge function */
1305 static int process_entry(struct merge_options *o,
1306                          const char *path, struct stage_data *entry)
1307 {
1308         /*
1309         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1310         print_index_entry("\tpath: ", entry);
1311         */
1312         int clean_merge = 1;
1313         int normalize = o->renormalize;
1314         unsigned o_mode = entry->stages[1].mode;
1315         unsigned a_mode = entry->stages[2].mode;
1316         unsigned b_mode = entry->stages[3].mode;
1317         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1318         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1319         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1320
1321         if (entry->rename_df_conflict_info)
1322                 return 1; /* Such cases are handled elsewhere. */
1323
1324         entry->processed = 1;
1325         if (o_sha && (!a_sha || !b_sha)) {
1326                 /* Case A: Deleted in one */
1327                 if ((!a_sha && !b_sha) ||
1328                     (!b_sha && blob_unchanged(o_sha, a_sha, normalize, path)) ||
1329                     (!a_sha && blob_unchanged(o_sha, b_sha, normalize, path))) {
1330                         /* Deleted in both or deleted in one and
1331                          * unchanged in the other */
1332                         if (a_sha)
1333                                 output(o, 2, "Removing %s", path);
1334                         /* do not touch working file if it did not exist */
1335                         remove_file(o, 1, path, !a_sha);
1336                 } else if (string_list_has_string(&o->current_directory_set,
1337                                                   path)) {
1338                         entry->processed = 0;
1339                         return 1; /* Assume clean until processed */
1340                 } else {
1341                         /* Deleted in one and changed in the other */
1342                         clean_merge = 0;
1343                         handle_delete_modify(o, path, path,
1344                                              a_sha, a_mode, b_sha, b_mode);
1345                 }
1346
1347         } else if ((!o_sha && a_sha && !b_sha) ||
1348                    (!o_sha && !a_sha && b_sha)) {
1349                 /* Case B: Added in one. */
1350                 unsigned mode;
1351                 const unsigned char *sha;
1352
1353                 if (a_sha) {
1354                         mode = a_mode;
1355                         sha = a_sha;
1356                 } else {
1357                         mode = b_mode;
1358                         sha = b_sha;
1359                 }
1360                 if (string_list_has_string(&o->current_directory_set, path)) {
1361                         /* Handle D->F conflicts after all subfiles */
1362                         entry->processed = 0;
1363                         return 1; /* Assume clean until processed */
1364                 } else {
1365                         output(o, 2, "Adding %s", path);
1366                         update_file(o, 1, sha, mode, path);
1367                 }
1368         } else if (a_sha && b_sha) {
1369                 /* Case C: Added in both (check for same permissions) and */
1370                 /* case D: Modified in both, but differently. */
1371                 clean_merge = merge_content(o, path,
1372                                             o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
1373                                             NULL);
1374         } else if (!o_sha && !a_sha && !b_sha) {
1375                 /*
1376                  * this entry was deleted altogether. a_mode == 0 means
1377                  * we had that path and want to actively remove it.
1378                  */
1379                 remove_file(o, 1, path, !a_mode);
1380         } else
1381                 die("Fatal merge failure, shouldn't happen.");
1382
1383         return clean_merge;
1384 }
1385
1386 /*
1387  * Per entry merge function for D/F (and/or rename) conflicts.  In the
1388  * cases we can cleanly resolve D/F conflicts, process_entry() can
1389  * clean out all the files below the directory for us.  All D/F
1390  * conflict cases must be handled here at the end to make sure any
1391  * directories that can be cleaned out, are.
1392  *
1393  * Some rename conflicts may also be handled here that don't necessarily
1394  * involve D/F conflicts, since the code to handle them is generic enough
1395  * to handle those rename conflicts with or without D/F conflicts also
1396  * being involved.
1397  */
1398 static int process_df_entry(struct merge_options *o,
1399                             const char *path, struct stage_data *entry)
1400 {
1401         int clean_merge = 1;
1402         unsigned o_mode = entry->stages[1].mode;
1403         unsigned a_mode = entry->stages[2].mode;
1404         unsigned b_mode = entry->stages[3].mode;
1405         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1406         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1407         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1408         struct stat st;
1409
1410         entry->processed = 1;
1411         if (entry->rename_df_conflict_info) {
1412                 struct rename_df_conflict_info *conflict_info = entry->rename_df_conflict_info;
1413                 char *src;
1414                 switch (conflict_info->rename_type) {
1415                 case RENAME_NORMAL:
1416                         clean_merge = merge_content(o, path,
1417                                                     o_sha, o_mode, a_sha, a_mode, b_sha, b_mode,
1418                                                     conflict_info->branch1);
1419                         break;
1420                 case RENAME_DELETE:
1421                         clean_merge = 0;
1422                         conflict_rename_delete(o, conflict_info->pair1,
1423                                                conflict_info->branch1,
1424                                                conflict_info->branch2);
1425                         break;
1426                 case RENAME_ONE_FILE_TO_TWO:
1427                         src = conflict_info->pair1->one->path;
1428                         clean_merge = 0;
1429                         output(o, 1, "CONFLICT (rename/rename): "
1430                                "Rename \"%s\"->\"%s\" in branch \"%s\" "
1431                                "rename \"%s\"->\"%s\" in \"%s\"%s",
1432                                src, conflict_info->pair1->two->path, conflict_info->branch1,
1433                                src, conflict_info->pair2->two->path, conflict_info->branch2,
1434                                o->call_depth ? " (left unresolved)" : "");
1435                         if (o->call_depth) {
1436                                 remove_file_from_cache(src);
1437                                 update_file(o, 0, conflict_info->pair1->one->sha1,
1438                                             conflict_info->pair1->one->mode, src);
1439                         }
1440                         conflict_rename_rename_1to2(o, conflict_info->pair1,
1441                                                     conflict_info->branch1,
1442                                                     conflict_info->pair2,
1443                                                     conflict_info->branch2);
1444                         conflict_info->dst_entry2->processed = 1;
1445                         break;
1446                 default:
1447                         entry->processed = 0;
1448                         break;
1449                 }
1450         } else if (o_sha && (!a_sha || !b_sha)) {
1451                 /* Modify/delete; deleted side may have put a directory in the way */
1452                 const char *new_path = path;
1453                 if (lstat(path, &st) == 0 && S_ISDIR(st.st_mode))
1454                         new_path = unique_path(o, path, a_sha ? o->branch1 : o->branch2);
1455                 clean_merge = 0;
1456                 handle_delete_modify(o, path, new_path,
1457                                      a_sha, a_mode, b_sha, b_mode);
1458         } else if (!o_sha && !!a_sha != !!b_sha) {
1459                 /* directory -> (directory, file) */
1460                 const char *add_branch;
1461                 const char *other_branch;
1462                 unsigned mode;
1463                 const unsigned char *sha;
1464                 const char *conf;
1465
1466                 if (a_sha) {
1467                         add_branch = o->branch1;
1468                         other_branch = o->branch2;
1469                         mode = a_mode;
1470                         sha = a_sha;
1471                         conf = "file/directory";
1472                 } else {
1473                         add_branch = o->branch2;
1474                         other_branch = o->branch1;
1475                         mode = b_mode;
1476                         sha = b_sha;
1477                         conf = "directory/file";
1478                 }
1479                 if (lstat(path, &st) == 0 && S_ISDIR(st.st_mode)) {
1480                         const char *new_path = unique_path(o, path, add_branch);
1481                         clean_merge = 0;
1482                         output(o, 1, "CONFLICT (%s): There is a directory with name %s in %s. "
1483                                "Adding %s as %s",
1484                                conf, path, other_branch, path, new_path);
1485                         update_file(o, 0, sha, mode, new_path);
1486                 } else {
1487                         output(o, 2, "Adding %s", path);
1488                         update_file(o, 1, sha, mode, path);
1489                 }
1490         } else {
1491                 entry->processed = 0;
1492                 return 1; /* not handled; assume clean until processed */
1493         }
1494
1495         return clean_merge;
1496 }
1497
1498 int merge_trees(struct merge_options *o,
1499                 struct tree *head,
1500                 struct tree *merge,
1501                 struct tree *common,
1502                 struct tree **result)
1503 {
1504         int code, clean;
1505
1506         if (o->subtree_shift) {
1507                 merge = shift_tree_object(head, merge, o->subtree_shift);
1508                 common = shift_tree_object(head, common, o->subtree_shift);
1509         }
1510
1511         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1512                 output(o, 0, "Already up-to-date!");
1513                 *result = head;
1514                 return 1;
1515         }
1516
1517         code = git_merge_trees(o->call_depth, common, head, merge);
1518
1519         if (code != 0) {
1520                 if (show(o, 4) || o->call_depth)
1521                         die("merging of trees %s and %s failed",
1522                             sha1_to_hex(head->object.sha1),
1523                             sha1_to_hex(merge->object.sha1));
1524                 else
1525                         exit(128);
1526         }
1527
1528         if (unmerged_cache()) {
1529                 struct string_list *entries, *re_head, *re_merge;
1530                 int i;
1531                 string_list_clear(&o->current_file_set, 1);
1532                 string_list_clear(&o->current_directory_set, 1);
1533                 get_files_dirs(o, head);
1534                 get_files_dirs(o, merge);
1535
1536                 entries = get_unmerged();
1537                 make_room_for_directories_of_df_conflicts(o, entries);
1538                 re_head  = get_renames(o, head, common, head, merge, entries);
1539                 re_merge = get_renames(o, merge, common, head, merge, entries);
1540                 clean = process_renames(o, re_head, re_merge);
1541                 for (i = 0; i < entries->nr; i++) {
1542                         const char *path = entries->items[i].string;
1543                         struct stage_data *e = entries->items[i].util;
1544                         if (!e->processed
1545                                 && !process_entry(o, path, e))
1546                                 clean = 0;
1547                 }
1548                 for (i = 0; i < entries->nr; i++) {
1549                         const char *path = entries->items[i].string;
1550                         struct stage_data *e = entries->items[i].util;
1551                         if (!e->processed
1552                                 && !process_df_entry(o, path, e))
1553                                 clean = 0;
1554                 }
1555                 for (i = 0; i < entries->nr; i++) {
1556                         struct stage_data *e = entries->items[i].util;
1557                         if (!e->processed)
1558                                 die("Unprocessed path??? %s",
1559                                     entries->items[i].string);
1560                 }
1561
1562                 string_list_clear(re_merge, 0);
1563                 string_list_clear(re_head, 0);
1564                 string_list_clear(entries, 1);
1565
1566         }
1567         else
1568                 clean = 1;
1569
1570         if (o->call_depth)
1571                 *result = write_tree_from_memory(o);
1572
1573         return clean;
1574 }
1575
1576 static struct commit_list *reverse_commit_list(struct commit_list *list)
1577 {
1578         struct commit_list *next = NULL, *current, *backup;
1579         for (current = list; current; current = backup) {
1580                 backup = current->next;
1581                 current->next = next;
1582                 next = current;
1583         }
1584         return next;
1585 }
1586
1587 /*
1588  * Merge the commits h1 and h2, return the resulting virtual
1589  * commit object and a flag indicating the cleanness of the merge.
1590  */
1591 int merge_recursive(struct merge_options *o,
1592                     struct commit *h1,
1593                     struct commit *h2,
1594                     struct commit_list *ca,
1595                     struct commit **result)
1596 {
1597         struct commit_list *iter;
1598         struct commit *merged_common_ancestors;
1599         struct tree *mrtree = mrtree;
1600         int clean;
1601
1602         if (show(o, 4)) {
1603                 output(o, 4, "Merging:");
1604                 output_commit_title(o, h1);
1605                 output_commit_title(o, h2);
1606         }
1607
1608         if (!ca) {
1609                 ca = get_merge_bases(h1, h2, 1);
1610                 ca = reverse_commit_list(ca);
1611         }
1612
1613         if (show(o, 5)) {
1614                 output(o, 5, "found %u common ancestor(s):", commit_list_count(ca));
1615                 for (iter = ca; iter; iter = iter->next)
1616                         output_commit_title(o, iter->item);
1617         }
1618
1619         merged_common_ancestors = pop_commit(&ca);
1620         if (merged_common_ancestors == NULL) {
1621                 /* if there is no common ancestor, make an empty tree */
1622                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1623
1624                 tree->object.parsed = 1;
1625                 tree->object.type = OBJ_TREE;
1626                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1627                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1628         }
1629
1630         for (iter = ca; iter; iter = iter->next) {
1631                 const char *saved_b1, *saved_b2;
1632                 o->call_depth++;
1633                 /*
1634                  * When the merge fails, the result contains files
1635                  * with conflict markers. The cleanness flag is
1636                  * ignored, it was never actually used, as result of
1637                  * merge_trees has always overwritten it: the committed
1638                  * "conflicts" were already resolved.
1639                  */
1640                 discard_cache();
1641                 saved_b1 = o->branch1;
1642                 saved_b2 = o->branch2;
1643                 o->branch1 = "Temporary merge branch 1";
1644                 o->branch2 = "Temporary merge branch 2";
1645                 merge_recursive(o, merged_common_ancestors, iter->item,
1646                                 NULL, &merged_common_ancestors);
1647                 o->branch1 = saved_b1;
1648                 o->branch2 = saved_b2;
1649                 o->call_depth--;
1650
1651                 if (!merged_common_ancestors)
1652                         die("merge returned no commit");
1653         }
1654
1655         discard_cache();
1656         if (!o->call_depth)
1657                 read_cache();
1658
1659         o->ancestor = "merged common ancestors";
1660         clean = merge_trees(o, h1->tree, h2->tree, merged_common_ancestors->tree,
1661                             &mrtree);
1662
1663         if (o->call_depth) {
1664                 *result = make_virtual_commit(mrtree, "merged tree");
1665                 commit_list_insert(h1, &(*result)->parents);
1666                 commit_list_insert(h2, &(*result)->parents->next);
1667         }
1668         flush_output(o);
1669         return clean;
1670 }
1671
1672 static struct commit *get_ref(const unsigned char *sha1, const char *name)
1673 {
1674         struct object *object;
1675
1676         object = deref_tag(parse_object(sha1), name, strlen(name));
1677         if (!object)
1678                 return NULL;
1679         if (object->type == OBJ_TREE)
1680                 return make_virtual_commit((struct tree*)object, name);
1681         if (object->type != OBJ_COMMIT)
1682                 return NULL;
1683         if (parse_commit((struct commit *)object))
1684                 return NULL;
1685         return (struct commit *)object;
1686 }
1687
1688 int merge_recursive_generic(struct merge_options *o,
1689                             const unsigned char *head,
1690                             const unsigned char *merge,
1691                             int num_base_list,
1692                             const unsigned char **base_list,
1693                             struct commit **result)
1694 {
1695         int clean, index_fd;
1696         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1697         struct commit *head_commit = get_ref(head, o->branch1);
1698         struct commit *next_commit = get_ref(merge, o->branch2);
1699         struct commit_list *ca = NULL;
1700
1701         if (base_list) {
1702                 int i;
1703                 for (i = 0; i < num_base_list; ++i) {
1704                         struct commit *base;
1705                         if (!(base = get_ref(base_list[i], sha1_to_hex(base_list[i]))))
1706                                 return error("Could not parse object '%s'",
1707                                         sha1_to_hex(base_list[i]));
1708                         commit_list_insert(base, &ca);
1709                 }
1710         }
1711
1712         index_fd = hold_locked_index(lock, 1);
1713         clean = merge_recursive(o, head_commit, next_commit, ca,
1714                         result);
1715         if (active_cache_changed &&
1716                         (write_cache(index_fd, active_cache, active_nr) ||
1717                          commit_locked_index(lock)))
1718                 return error("Unable to write index.");
1719
1720         return clean ? 0 : 1;
1721 }
1722
1723 static int merge_recursive_config(const char *var, const char *value, void *cb)
1724 {
1725         struct merge_options *o = cb;
1726         if (!strcasecmp(var, "merge.verbosity")) {
1727                 o->verbosity = git_config_int(var, value);
1728                 return 0;
1729         }
1730         if (!strcasecmp(var, "diff.renamelimit")) {
1731                 o->diff_rename_limit = git_config_int(var, value);
1732                 return 0;
1733         }
1734         if (!strcasecmp(var, "merge.renamelimit")) {
1735                 o->merge_rename_limit = git_config_int(var, value);
1736                 return 0;
1737         }
1738         return git_xmerge_config(var, value, cb);
1739 }
1740
1741 void init_merge_options(struct merge_options *o)
1742 {
1743         memset(o, 0, sizeof(struct merge_options));
1744         o->verbosity = 2;
1745         o->buffer_output = 1;
1746         o->diff_rename_limit = -1;
1747         o->merge_rename_limit = -1;
1748         o->renormalize = 0;
1749         git_config(merge_recursive_config, o);
1750         if (getenv("GIT_MERGE_VERBOSITY"))
1751                 o->verbosity =
1752                         strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1753         if (o->verbosity >= 5)
1754                 o->buffer_output = 0;
1755         strbuf_init(&o->obuf, 0);
1756         memset(&o->current_file_set, 0, sizeof(struct string_list));
1757         o->current_file_set.strdup_strings = 1;
1758         memset(&o->current_directory_set, 0, sizeof(struct string_list));
1759         o->current_directory_set.strdup_strings = 1;
1760 }
1761
1762 int parse_merge_opt(struct merge_options *o, const char *s)
1763 {
1764         if (!s || !*s)
1765                 return -1;
1766         if (!strcmp(s, "ours"))
1767                 o->recursive_variant = MERGE_RECURSIVE_OURS;
1768         else if (!strcmp(s, "theirs"))
1769                 o->recursive_variant = MERGE_RECURSIVE_THEIRS;
1770         else if (!strcmp(s, "subtree"))
1771                 o->subtree_shift = "";
1772         else if (!prefixcmp(s, "subtree="))
1773                 o->subtree_shift = s + strlen("subtree=");
1774         else if (!strcmp(s, "patience"))
1775                 o->xdl_opts |= XDF_PATIENCE_DIFF;
1776         else if (!strcmp(s, "ignore-space-change"))
1777                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_CHANGE;
1778         else if (!strcmp(s, "ignore-all-space"))
1779                 o->xdl_opts |= XDF_IGNORE_WHITESPACE;
1780         else if (!strcmp(s, "ignore-space-at-eol"))
1781                 o->xdl_opts |= XDF_IGNORE_WHITESPACE_AT_EOL;
1782         else if (!strcmp(s, "renormalize"))
1783                 o->renormalize = 1;
1784         else if (!strcmp(s, "no-renormalize"))
1785                 o->renormalize = 0;
1786         else if (!prefixcmp(s, "rename-threshold=")) {
1787                 const char *score = s + strlen("rename-threshold=");
1788                 if ((o->rename_score = parse_rename_score(&score)) == -1 || *score != 0)
1789                         return -1;
1790         }
1791         else
1792                 return -1;
1793         return 0;
1794 }