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