merge-recursive.c

   1 /*
   2  * Recursive Merge algorithm stolen from git-merge-recursive.py by
   3  * Fredrik Kuivinen.
   4  * The thieves were Alex Riesen and Johannes Schindelin, in June/July 2006
   5  */
   6 #include "cache.h"
   7 #include "cache-tree.h"
   8 #include "commit.h"
   9 #include "blob.h"
  10 #include "tree-walk.h"
  11 #include "diff.h"
  12 #include "diffcore.h"
  13 #include "run-command.h"
  14 #include "tag.h"
  15 #include "unpack-trees.h"
  16 #include "path-list.h"
  17 #include "xdiff-interface.h"
  18
  19 /*
  20  * A virtual commit has
  21  * - (const char *)commit->util set to the name, and
  22  * - *(int *)commit->object.sha1 set to the virtual id.
  23  */
  24
  25 static unsigned commit_list_count(const struct commit_list *l)
  26 {
  27         unsigned c = 0;
  28         for (; l; l = l->next )
  29                 c++;
  30         return c;
  31 }
  32
  33 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  34 {
  35         struct commit *commit = xcalloc(1, sizeof(struct commit));
  36         static unsigned virtual_id = 1;
  37         commit->tree = tree;
  38         commit->util = (void*)comment;
  39         *(int*)commit->object.sha1 = virtual_id++;
  40         /* avoid warnings */
  41         commit->object.parsed = 1;
  42         return commit;
  43 }
  44
  45 /*
  46  * Since we use get_tree_entry(), which does not put the read object into
  47  * the object pool, we cannot rely on a == b.
  48  */
  49 static int sha_eq(const unsigned char *a, const unsigned char *b)
  50 {
  51         if (!a && !b)
  52                 return 2;
  53         return a && b && hashcmp(a, b) == 0;
  54 }
  55
  56 /*
  57  * Since we want to write the index eventually, we cannot reuse the index
  58  * for these (temporary) data.
  59  */
  60 struct stage_data
  61 {
  62         struct
  63         {
  64                 unsigned mode;
  65                 unsigned char sha[20];
  66         } stages[4];
  67         unsigned processed:1;
  68 };
  69
  70 static struct path_list current_file_set = {NULL, 0, 0, 1};
  71 static struct path_list current_directory_set = {NULL, 0, 0, 1};
  72
  73 static int output_indent = 0;
  74
  75 static void output(const char *fmt, ...)
  76 {
  77         va_list args;
  78         int i;
  79         for (i = output_indent; i--;)
  80                 fputs("  ", stdout);
  81         va_start(args, fmt);
  82         vfprintf(stdout, fmt, args);
  83         va_end(args);
  84         fputc('\n', stdout);
  85 }
  86
  87 static void output_commit_title(struct commit *commit)
  88 {
  89         int i;
  90         for (i = output_indent; i--;)
  91                 fputs("  ", stdout);
  92         if (commit->util)
  93                 printf("virtual %s\n", (char *)commit->util);
  94         else {
  95                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
  96                 if (parse_commit(commit) != 0)
  97                         printf("(bad commit)\n");
  98                 else {
  99                         const char *s;
 100                         int len;
 101                         for (s = commit->buffer; *s; s++)
 102                                 if (*s == '\n' && s[1] == '\n') {
 103                                         s += 2;
 104                                         break;
 105                                 }
 106                         for (len = 0; s[len] && '\n' != s[len]; len++)
 107                                 ; /* do nothing */
 108                         printf("%.*s\n", len, s);
 109                 }
 110         }
 111 }
 112
 113 static struct cache_entry *make_cache_entry(unsigned int mode,
 114                 const unsigned char *sha1, const char *path, int stage, int refresh)
 115 {
 116         int size, len;
 117         struct cache_entry *ce;
 118
 119         if (!verify_path(path))
 120                 return NULL;
 121
 122         len = strlen(path);
 123         size = cache_entry_size(len);
 124         ce = xcalloc(1, size);
 125
 126         hashcpy(ce->sha1, sha1);
 127         memcpy(ce->name, path, len);
 128         ce->ce_flags = create_ce_flags(len, stage);
 129         ce->ce_mode = create_ce_mode(mode);
 130
 131         if (refresh)
 132                 return refresh_cache_entry(ce, 0);
 133
 134         return ce;
 135 }
 136
 137 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 138                 const char *path, int stage, int refresh, int options)
 139 {
 140         struct cache_entry *ce;
 141         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 142         if (!ce)
 143                 return error("cache_addinfo failed: %s", strerror(cache_errno));
 144         return add_cache_entry(ce, options);
 145 }
 146
 147 /*
 148  * This is a global variable which is used in a number of places but
 149  * only written to in the 'merge' function.
 150  *
 151  * index_only == 1    => Don't leave any non-stage 0 entries in the cache and
 152  *                       don't update the working directory.
 153  *               0    => Leave unmerged entries in the cache and update
 154  *                       the working directory.
 155  */
 156 static int index_only = 0;
 157
 158 static int git_merge_trees(int index_only,
 159                            struct tree *common,
 160                            struct tree *head,
 161                            struct tree *merge)
 162 {
 163         int rc;
 164         struct object_list *trees = NULL;
 165         struct unpack_trees_options opts;
 166
 167         memset(&opts, 0, sizeof(opts));
 168         if (index_only)
 169                 opts.index_only = 1;
 170         else
 171                 opts.update = 1;
 172         opts.merge = 1;
 173         opts.head_idx = 2;
 174         opts.fn = threeway_merge;
 175
 176         object_list_append(&common->object, &trees);
 177         object_list_append(&head->object, &trees);
 178         object_list_append(&merge->object, &trees);
 179
 180         rc = unpack_trees(trees, &opts);
 181         cache_tree_free(&active_cache_tree);
 182         return rc;
 183 }
 184
 185 static int unmerged_index(void)
 186 {
 187         int i;
 188         for (i = 0; i < active_nr; i++) {
 189                 struct cache_entry *ce = active_cache[i];
 190                 if (ce_stage(ce))
 191                         return 1;
 192         }
 193         return 0;
 194 }
 195
 196 static struct tree *git_write_tree(void)
 197 {
 198         struct tree *result = NULL;
 199
 200         if (unmerged_index())
 201                 return NULL;
 202
 203         if (!active_cache_tree)
 204                 active_cache_tree = cache_tree();
 205
 206         if (!cache_tree_fully_valid(active_cache_tree) &&
 207             cache_tree_update(active_cache_tree,
 208                               active_cache, active_nr, 0, 0) < 0)
 209                 die("error building trees");
 210
 211         result = lookup_tree(active_cache_tree->sha1);
 212
 213         return result;
 214 }
 215
 216 static int save_files_dirs(const unsigned char *sha1,
 217                 const char *base, int baselen, const char *path,
 218                 unsigned int mode, int stage)
 219 {
 220         int len = strlen(path);
 221         char *newpath = xmalloc(baselen + len + 1);
 222         memcpy(newpath, base, baselen);
 223         memcpy(newpath + baselen, path, len);
 224         newpath[baselen + len] = '\0';
 225
 226         if (S_ISDIR(mode))
 227                 path_list_insert(newpath, &current_directory_set);
 228         else
 229                 path_list_insert(newpath, &current_file_set);
 230         free(newpath);
 231
 232         return READ_TREE_RECURSIVE;
 233 }
 234
 235 static int get_files_dirs(struct tree *tree)
 236 {
 237         int n;
 238         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs) != 0)
 239                 return 0;
 240         n = current_file_set.nr + current_directory_set.nr;
 241         return n;
 242 }
 243
 244 /*
 245  * Returns a index_entry instance which doesn't have to correspond to
 246  * a real cache entry in Git's index.
 247  */
 248 static struct stage_data *insert_stage_data(const char *path,
 249                 struct tree *o, struct tree *a, struct tree *b,
 250                 struct path_list *entries)
 251 {
 252         struct path_list_item *item;
 253         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 254         get_tree_entry(o->object.sha1, path,
 255                         e->stages[1].sha, &e->stages[1].mode);
 256         get_tree_entry(a->object.sha1, path,
 257                         e->stages[2].sha, &e->stages[2].mode);
 258         get_tree_entry(b->object.sha1, path,
 259                         e->stages[3].sha, &e->stages[3].mode);
 260         item = path_list_insert(path, entries);
 261         item->util = e;
 262         return e;
 263 }
 264
 265 /*
 266  * Create a dictionary mapping file names to stage_data objects. The
 267  * dictionary contains one entry for every path with a non-zero stage entry.
 268  */
 269 static struct path_list *get_unmerged(void)
 270 {
 271         struct path_list *unmerged = xcalloc(1, sizeof(struct path_list));
 272         int i;
 273
 274         unmerged->strdup_paths = 1;
 275
 276         for (i = 0; i < active_nr; i++) {
 277                 struct path_list_item *item;
 278                 struct stage_data *e;
 279                 struct cache_entry *ce = active_cache[i];
 280                 if (!ce_stage(ce))
 281                         continue;
 282
 283                 item = path_list_lookup(ce->name, unmerged);
 284                 if (!item) {
 285                         item = path_list_insert(ce->name, unmerged);
 286                         item->util = xcalloc(1, sizeof(struct stage_data));
 287                 }
 288                 e = item->util;
 289                 e->stages[ce_stage(ce)].mode = ntohl(ce->ce_mode);
 290                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 291         }
 292
 293         return unmerged;
 294 }
 295
 296 struct rename
 297 {
 298         struct diff_filepair *pair;
 299         struct stage_data *src_entry;
 300         struct stage_data *dst_entry;
 301         unsigned processed:1;
 302 };
 303
 304 /*
 305  * Get information of all renames which occured between 'o_tree' and
 306  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 307  * 'b_tree') to be able to associate the correct cache entries with
 308  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 309  */
 310 static struct path_list *get_renames(struct tree *tree,
 311                                         struct tree *o_tree,
 312                                         struct tree *a_tree,
 313                                         struct tree *b_tree,
 314                                         struct path_list *entries)
 315 {
 316         int i;
 317         struct path_list *renames;
 318         struct diff_options opts;
 319
 320         renames = xcalloc(1, sizeof(struct path_list));
 321         diff_setup(&opts);
 322         opts.recursive = 1;
 323         opts.detect_rename = DIFF_DETECT_RENAME;
 324         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 325         if (diff_setup_done(&opts) < 0)
 326                 die("diff setup failed");
 327         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 328         diffcore_std(&opts);
 329         for (i = 0; i < diff_queued_diff.nr; ++i) {
 330                 struct path_list_item *item;
 331                 struct rename *re;
 332                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 333                 if (pair->status != 'R') {
 334                         diff_free_filepair(pair);
 335                         continue;
 336                 }
 337                 re = xmalloc(sizeof(*re));
 338                 re->processed = 0;
 339                 re->pair = pair;
 340                 item = path_list_lookup(re->pair->one->path, entries);
 341                 if (!item)
 342                         re->src_entry = insert_stage_data(re->pair->one->path,
 343                                         o_tree, a_tree, b_tree, entries);
 344                 else
 345                         re->src_entry = item->util;
 346
 347                 item = path_list_lookup(re->pair->two->path, entries);
 348                 if (!item)
 349                         re->dst_entry = insert_stage_data(re->pair->two->path,
 350                                         o_tree, a_tree, b_tree, entries);
 351                 else
 352                         re->dst_entry = item->util;
 353                 item = path_list_insert(pair->one->path, renames);
 354                 item->util = re;
 355         }
 356         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 357         diff_queued_diff.nr = 0;
 358         diff_flush(&opts);
 359         return renames;
 360 }
 361
 362 static int update_stages(const char *path, struct diff_filespec *o,
 363                          struct diff_filespec *a, struct diff_filespec *b,
 364                          int clear)
 365 {
 366         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 367         if (clear)
 368                 if (remove_file_from_cache(path))
 369                         return -1;
 370         if (o)
 371                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 372                         return -1;
 373         if (a)
 374                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 375                         return -1;
 376         if (b)
 377                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 378                         return -1;
 379         return 0;
 380 }
 381
 382 static int remove_path(const char *name)
 383 {
 384         int ret, len;
 385         char *slash, *dirs;
 386
 387         ret = unlink(name);
 388         if (ret)
 389                 return ret;
 390         len = strlen(name);
 391         dirs = xmalloc(len+1);
 392         memcpy(dirs, name, len);
 393         dirs[len] = '\0';
 394         while ((slash = strrchr(name, '/'))) {
 395                 *slash = '\0';
 396                 len = slash - name;
 397                 if (rmdir(name) != 0)
 398                         break;
 399         }
 400         free(dirs);
 401         return ret;
 402 }
 403
 404 static int remove_file(int clean, const char *path, int no_wd)
 405 {
 406         int update_cache = index_only || clean;
 407         int update_working_directory = !index_only && !no_wd;
 408
 409         if (update_cache) {
 410                 if (remove_file_from_cache(path))
 411                         return -1;
 412         }
 413         if (update_working_directory) {
 414                 unlink(path);
 415                 if (errno != ENOENT || errno != EISDIR)
 416                         return -1;
 417                 remove_path(path);
 418         }
 419         return 0;
 420 }
 421
 422 static char *unique_path(const char *path, const char *branch)
 423 {
 424         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 425         int suffix = 0;
 426         struct stat st;
 427         char *p = newpath + strlen(path);
 428         strcpy(newpath, path);
 429         *(p++) = '~';
 430         strcpy(p, branch);
 431         for (; *p; ++p)
 432                 if ('/' == *p)
 433                         *p = '_';
 434         while (path_list_has_path(&current_file_set, newpath) ||
 435                path_list_has_path(&current_directory_set, newpath) ||
 436                lstat(newpath, &st) == 0)
 437                 sprintf(p, "_%d", suffix++);
 438
 439         path_list_insert(newpath, &current_file_set);
 440         return newpath;
 441 }
 442
 443 static int mkdir_p(const char *path, unsigned long mode)
 444 {
 445         /* path points to cache entries, so xstrdup before messing with it */
 446         char *buf = xstrdup(path);
 447         int result = safe_create_leading_directories(buf);
 448         free(buf);
 449         return result;
 450 }
 451
 452 static void flush_buffer(int fd, const char *buf, unsigned long size)
 453 {
 454         while (size > 0) {
 455                 long ret = write_in_full(fd, buf, size);
 456                 if (ret < 0) {
 457                         /* Ignore epipe */
 458                         if (errno == EPIPE)
 459                                 break;
 460                         die("merge-recursive: %s", strerror(errno));
 461                 } else if (!ret) {
 462                         die("merge-recursive: disk full?");
 463                 }
 464                 size -= ret;
 465                 buf += ret;
 466         }
 467 }
 468
 469 static void update_file_flags(const unsigned char *sha,
 470                               unsigned mode,
 471                               const char *path,
 472                               int update_cache,
 473                               int update_wd)
 474 {
 475         if (index_only)
 476                 update_wd = 0;
 477
 478         if (update_wd) {
 479                 char type[20];
 480                 void *buf;
 481                 unsigned long size;
 482
 483                 buf = read_sha1_file(sha, type, &size);
 484                 if (!buf)
 485                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 486                 if (strcmp(type, blob_type) != 0)
 487                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 488
 489                 if (S_ISREG(mode)) {
 490                         int fd;
 491                         if (mkdir_p(path, 0777))
 492                                 die("failed to create path %s: %s", path, strerror(errno));
 493                         unlink(path);
 494                         if (mode & 0100)
 495                                 mode = 0777;
 496                         else
 497                                 mode = 0666;
 498                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 499                         if (fd < 0)
 500                                 die("failed to open %s: %s", path, strerror(errno));
 501                         flush_buffer(fd, buf, size);
 502                         close(fd);
 503                 } else if (S_ISLNK(mode)) {
 504                         char *lnk = xmalloc(size + 1);
 505                         memcpy(lnk, buf, size);
 506                         lnk[size] = '\0';
 507                         mkdir_p(path, 0777);
 508                         unlink(lnk);
 509                         symlink(lnk, path);
 510                 } else
 511                         die("do not know what to do with %06o %s '%s'",
 512                             mode, sha1_to_hex(sha), path);
 513         }
 514         if (update_cache)
 515                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 516 }
 517
 518 static void update_file(int clean,
 519                         const unsigned char *sha,
 520                         unsigned mode,
 521                         const char *path)
 522 {
 523         update_file_flags(sha, mode, path, index_only || clean, !index_only);
 524 }
 525
 526 /* Low level file merging, update and removal */
 527
 528 struct merge_file_info
 529 {
 530         unsigned char sha[20];
 531         unsigned mode;
 532         unsigned clean:1,
 533                  merge:1;
 534 };
 535
 536 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 537 {
 538         unsigned long size;
 539         char type[20];
 540
 541         if (!hashcmp(sha1, null_sha1)) {
 542                 mm->ptr = xstrdup("");
 543                 mm->size = 0;
 544                 return;
 545         }
 546
 547         mm->ptr = read_sha1_file(sha1, type, &size);
 548         if (!mm->ptr || strcmp(type, blob_type))
 549                 die("unable to read blob object %s", sha1_to_hex(sha1));
 550         mm->size = size;
 551 }
 552
 553 static struct merge_file_info merge_file(struct diff_filespec *o,
 554                 struct diff_filespec *a, struct diff_filespec *b,
 555                 const char *branch1, const char *branch2)
 556 {
 557         struct merge_file_info result;
 558         result.merge = 0;
 559         result.clean = 1;
 560
 561         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
 562                 result.clean = 0;
 563                 if (S_ISREG(a->mode)) {
 564                         result.mode = a->mode;
 565                         hashcpy(result.sha, a->sha1);
 566                 } else {
 567                         result.mode = b->mode;
 568                         hashcpy(result.sha, b->sha1);
 569                 }
 570         } else {
 571                 if (!sha_eq(a->sha1, o->sha1) && !sha_eq(b->sha1, o->sha1))
 572                         result.merge = 1;
 573
 574                 result.mode = a->mode == o->mode ? b->mode: a->mode;
 575
 576                 if (sha_eq(a->sha1, o->sha1))
 577                         hashcpy(result.sha, b->sha1);
 578                 else if (sha_eq(b->sha1, o->sha1))
 579                         hashcpy(result.sha, a->sha1);
 580                 else if (S_ISREG(a->mode)) {
 581                         mmfile_t orig, src1, src2;
 582                         mmbuffer_t result_buf;
 583                         xpparam_t xpp;
 584                         char *name1, *name2;
 585                         int merge_status;
 586
 587                         name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 588                         name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 589
 590                         fill_mm(o->sha1, &orig);
 591                         fill_mm(a->sha1, &src1);
 592                         fill_mm(b->sha1, &src2);
 593
 594                         memset(&xpp, 0, sizeof(xpp));
 595                         merge_status = xdl_merge(&orig,
 596                                                  &src1, name1,
 597                                                  &src2, name2,
 598                                                  &xpp, XDL_MERGE_ZEALOUS,
 599                                                  &result_buf);
 600                         free(name1);
 601                         free(name2);
 602                         free(orig.ptr);
 603                         free(src1.ptr);
 604                         free(src2.ptr);
 605
 606                         if ((merge_status < 0) || !result_buf.ptr)
 607                                 die("Failed to execute internal merge");
 608
 609                         if (write_sha1_file(result_buf.ptr, result_buf.size,
 610                                             blob_type, result.sha))
 611                                 die("Unable to add %s to database",
 612                                     a->path);
 613
 614                         free(result_buf.ptr);
 615                         result.clean = (merge_status == 0);
 616                 } else {
 617                         if (!(S_ISLNK(a->mode) || S_ISLNK(b->mode)))
 618                                 die("cannot merge modes?");
 619
 620                         hashcpy(result.sha, a->sha1);
 621
 622                         if (!sha_eq(a->sha1, b->sha1))
 623                                 result.clean = 0;
 624                 }
 625         }
 626
 627         return result;
 628 }
 629
 630 static void conflict_rename_rename(struct rename *ren1,
 631                                    const char *branch1,
 632                                    struct rename *ren2,
 633                                    const char *branch2)
 634 {
 635         char *del[2];
 636         int delp = 0;
 637         const char *ren1_dst = ren1->pair->two->path;
 638         const char *ren2_dst = ren2->pair->two->path;
 639         const char *dst_name1 = ren1_dst;
 640         const char *dst_name2 = ren2_dst;
 641         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 642                 dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
 643                 output("%s is a directory in %s adding as %s instead",
 644                        ren1_dst, branch2, dst_name1);
 645                 remove_file(0, ren1_dst, 0);
 646         }
 647         if (path_list_has_path(&current_directory_set, ren2_dst)) {
 648                 dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
 649                 output("%s is a directory in %s adding as %s instead",
 650                        ren2_dst, branch1, dst_name2);
 651                 remove_file(0, ren2_dst, 0);
 652         }
 653         update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
 654         update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
 655         while (delp--)
 656                 free(del[delp]);
 657 }
 658
 659 static void conflict_rename_dir(struct rename *ren1,
 660                                 const char *branch1)
 661 {
 662         char *new_path = unique_path(ren1->pair->two->path, branch1);
 663         output("Renaming %s to %s instead", ren1->pair->one->path, new_path);
 664         remove_file(0, ren1->pair->two->path, 0);
 665         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
 666         free(new_path);
 667 }
 668
 669 static void conflict_rename_rename_2(struct rename *ren1,
 670                                      const char *branch1,
 671                                      struct rename *ren2,
 672                                      const char *branch2)
 673 {
 674         char *new_path1 = unique_path(ren1->pair->two->path, branch1);
 675         char *new_path2 = unique_path(ren2->pair->two->path, branch2);
 676         output("Renaming %s to %s and %s to %s instead",
 677                ren1->pair->one->path, new_path1,
 678                ren2->pair->one->path, new_path2);
 679         remove_file(0, ren1->pair->two->path, 0);
 680         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
 681         update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
 682         free(new_path2);
 683         free(new_path1);
 684 }
 685
 686 static int process_renames(struct path_list *a_renames,
 687                            struct path_list *b_renames,
 688                            const char *a_branch,
 689                            const char *b_branch)
 690 {
 691         int clean_merge = 1, i, j;
 692         struct path_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
 693         const struct rename *sre;
 694
 695         for (i = 0; i < a_renames->nr; i++) {
 696                 sre = a_renames->items[i].util;
 697                 path_list_insert(sre->pair->two->path, &a_by_dst)->util
 698                         = sre->dst_entry;
 699         }
 700         for (i = 0; i < b_renames->nr; i++) {
 701                 sre = b_renames->items[i].util;
 702                 path_list_insert(sre->pair->two->path, &b_by_dst)->util
 703                         = sre->dst_entry;
 704         }
 705
 706         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
 707                 int compare;
 708                 char *src;
 709                 struct path_list *renames1, *renames2, *renames2Dst;
 710                 struct rename *ren1 = NULL, *ren2 = NULL;
 711                 const char *branch1, *branch2;
 712                 const char *ren1_src, *ren1_dst;
 713
 714                 if (i >= a_renames->nr) {
 715                         compare = 1;
 716                         ren2 = b_renames->items[j++].util;
 717                 } else if (j >= b_renames->nr) {
 718                         compare = -1;
 719                         ren1 = a_renames->items[i++].util;
 720                 } else {
 721                         compare = strcmp(a_renames->items[i].path,
 722                                         b_renames->items[j].path);
 723                         if (compare <= 0)
 724                                 ren1 = a_renames->items[i++].util;
 725                         if (compare >= 0)
 726                                 ren2 = b_renames->items[j++].util;
 727                 }
 728
 729                 /* TODO: refactor, so that 1/2 are not needed */
 730                 if (ren1) {
 731                         renames1 = a_renames;
 732                         renames2 = b_renames;
 733                         renames2Dst = &b_by_dst;
 734                         branch1 = a_branch;
 735                         branch2 = b_branch;
 736                 } else {
 737                         struct rename *tmp;
 738                         renames1 = b_renames;
 739                         renames2 = a_renames;
 740                         renames2Dst = &a_by_dst;
 741                         branch1 = b_branch;
 742                         branch2 = a_branch;
 743                         tmp = ren2;
 744                         ren2 = ren1;
 745                         ren1 = tmp;
 746                 }
 747                 src = ren1->pair->one->path;
 748
 749                 ren1->dst_entry->processed = 1;
 750                 ren1->src_entry->processed = 1;
 751
 752                 if (ren1->processed)
 753                         continue;
 754                 ren1->processed = 1;
 755
 756                 ren1_src = ren1->pair->one->path;
 757                 ren1_dst = ren1->pair->two->path;
 758
 759                 if (ren2) {
 760                         const char *ren2_src = ren2->pair->one->path;
 761                         const char *ren2_dst = ren2->pair->two->path;
 762                         /* Renamed in 1 and renamed in 2 */
 763                         if (strcmp(ren1_src, ren2_src) != 0)
 764                                 die("ren1.src != ren2.src");
 765                         ren2->dst_entry->processed = 1;
 766                         ren2->processed = 1;
 767                         if (strcmp(ren1_dst, ren2_dst) != 0) {
 768                                 clean_merge = 0;
 769                                 output("CONFLICT (rename/rename): "
 770                                        "Rename %s->%s in branch %s "
 771                                        "rename %s->%s in %s",
 772                                        src, ren1_dst, branch1,
 773                                        src, ren2_dst, branch2);
 774                                 conflict_rename_rename(ren1, branch1, ren2, branch2);
 775                         } else {
 776                                 struct merge_file_info mfi;
 777                                 remove_file(1, ren1_src, 1);
 778                                 mfi = merge_file(ren1->pair->one,
 779                                                  ren1->pair->two,
 780                                                  ren2->pair->two,
 781                                                  branch1,
 782                                                  branch2);
 783                                 if (mfi.merge || !mfi.clean)
 784                                         output("Renaming %s->%s", src, ren1_dst);
 785
 786                                 if (mfi.merge)
 787                                         output("Auto-merging %s", ren1_dst);
 788
 789                                 if (!mfi.clean) {
 790                                         output("CONFLICT (content): merge conflict in %s",
 791                                                ren1_dst);
 792                                         clean_merge = 0;
 793
 794                                         if (!index_only)
 795                                                 update_stages(ren1_dst,
 796                                                               ren1->pair->one,
 797                                                               ren1->pair->two,
 798                                                               ren2->pair->two,
 799                                                               1 /* clear */);
 800                                 }
 801                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 802                         }
 803                 } else {
 804                         /* Renamed in 1, maybe changed in 2 */
 805                         struct path_list_item *item;
 806                         /* we only use sha1 and mode of these */
 807                         struct diff_filespec src_other, dst_other;
 808                         int try_merge, stage = a_renames == renames1 ? 3: 2;
 809
 810                         remove_file(1, ren1_src, index_only);
 811
 812                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
 813                         src_other.mode = ren1->src_entry->stages[stage].mode;
 814                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
 815                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
 816
 817                         try_merge = 0;
 818
 819                         if (path_list_has_path(&current_directory_set, ren1_dst)) {
 820                                 clean_merge = 0;
 821                                 output("CONFLICT (rename/directory): Rename %s->%s in %s "
 822                                        " directory %s added in %s",
 823                                        ren1_src, ren1_dst, branch1,
 824                                        ren1_dst, branch2);
 825                                 conflict_rename_dir(ren1, branch1);
 826                         } else if (sha_eq(src_other.sha1, null_sha1)) {
 827                                 clean_merge = 0;
 828                                 output("CONFLICT (rename/delete): Rename %s->%s in %s "
 829                                        "and deleted in %s",
 830                                        ren1_src, ren1_dst, branch1,
 831                                        branch2);
 832                                 update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
 833                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
 834                                 const char *new_path;
 835                                 clean_merge = 0;
 836                                 try_merge = 1;
 837                                 output("CONFLICT (rename/add): Rename %s->%s in %s. "
 838                                        "%s added in %s",
 839                                        ren1_src, ren1_dst, branch1,
 840                                        ren1_dst, branch2);
 841                                 new_path = unique_path(ren1_dst, branch2);
 842                                 output("Adding as %s instead", new_path);
 843                                 update_file(0, dst_other.sha1, dst_other.mode, new_path);
 844                         } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
 845                                 ren2 = item->util;
 846                                 clean_merge = 0;
 847                                 ren2->processed = 1;
 848                                 output("CONFLICT (rename/rename): Rename %s->%s in %s. "
 849                                        "Rename %s->%s in %s",
 850                                        ren1_src, ren1_dst, branch1,
 851                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
 852                                 conflict_rename_rename_2(ren1, branch1, ren2, branch2);
 853                         } else
 854                                 try_merge = 1;
 855
 856                         if (try_merge) {
 857                                 struct diff_filespec *o, *a, *b;
 858                                 struct merge_file_info mfi;
 859                                 src_other.path = (char *)ren1_src;
 860
 861                                 o = ren1->pair->one;
 862                                 if (a_renames == renames1) {
 863                                         a = ren1->pair->two;
 864                                         b = &src_other;
 865                                 } else {
 866                                         b = ren1->pair->two;
 867                                         a = &src_other;
 868                                 }
 869                                 mfi = merge_file(o, a, b,
 870                                                 a_branch, b_branch);
 871
 872                                 if (mfi.merge || !mfi.clean)
 873                                         output("Renaming %s => %s", ren1_src, ren1_dst);
 874                                 if (mfi.merge)
 875                                         output("Auto-merging %s", ren1_dst);
 876                                 if (!mfi.clean) {
 877                                         output("CONFLICT (rename/modify): Merge conflict in %s",
 878                                                ren1_dst);
 879                                         clean_merge = 0;
 880
 881                                         if (!index_only)
 882                                                 update_stages(ren1_dst,
 883                                                                 o, a, b, 1);
 884                                 }
 885                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
 886                         }
 887                 }
 888         }
 889         path_list_clear(&a_by_dst, 0);
 890         path_list_clear(&b_by_dst, 0);
 891
 892         return clean_merge;
 893 }
 894
 895 static unsigned char *has_sha(const unsigned char *sha)
 896 {
 897         return is_null_sha1(sha) ? NULL: (unsigned char *)sha;
 898 }
 899
 900 /* Per entry merge function */
 901 static int process_entry(const char *path, struct stage_data *entry,
 902                          const char *branch1,
 903                          const char *branch2)
 904 {
 905         /*
 906         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
 907         print_index_entry("\tpath: ", entry);
 908         */
 909         int clean_merge = 1;
 910         unsigned char *o_sha = has_sha(entry->stages[1].sha);
 911         unsigned char *a_sha = has_sha(entry->stages[2].sha);
 912         unsigned char *b_sha = has_sha(entry->stages[3].sha);
 913         unsigned o_mode = entry->stages[1].mode;
 914         unsigned a_mode = entry->stages[2].mode;
 915         unsigned b_mode = entry->stages[3].mode;
 916
 917         if (o_sha && (!a_sha || !b_sha)) {
 918                 /* Case A: Deleted in one */
 919                 if ((!a_sha && !b_sha) ||
 920                     (sha_eq(a_sha, o_sha) && !b_sha) ||
 921                     (!a_sha && sha_eq(b_sha, o_sha))) {
 922                         /* Deleted in both or deleted in one and
 923                          * unchanged in the other */
 924                         if (a_sha)
 925                                 output("Removing %s", path);
 926                         /* do not touch working file if it did not exist */
 927                         remove_file(1, path, !a_sha);
 928                 } else {
 929                         /* Deleted in one and changed in the other */
 930                         clean_merge = 0;
 931                         if (!a_sha) {
 932                                 output("CONFLICT (delete/modify): %s deleted in %s "
 933                                        "and modified in %s. Version %s of %s left in tree.",
 934                                        path, branch1,
 935                                        branch2, branch2, path);
 936                                 update_file(0, b_sha, b_mode, path);
 937                         } else {
 938                                 output("CONFLICT (delete/modify): %s deleted in %s "
 939                                        "and modified in %s. Version %s of %s left in tree.",
 940                                        path, branch2,
 941                                        branch1, branch1, path);
 942                                 update_file(0, a_sha, a_mode, path);
 943                         }
 944                 }
 945
 946         } else if ((!o_sha && a_sha && !b_sha) ||
 947                    (!o_sha && !a_sha && b_sha)) {
 948                 /* Case B: Added in one. */
 949                 const char *add_branch;
 950                 const char *other_branch;
 951                 unsigned mode;
 952                 const unsigned char *sha;
 953                 const char *conf;
 954
 955                 if (a_sha) {
 956                         add_branch = branch1;
 957                         other_branch = branch2;
 958                         mode = a_mode;
 959                         sha = a_sha;
 960                         conf = "file/directory";
 961                 } else {
 962                         add_branch = branch2;
 963                         other_branch = branch1;
 964                         mode = b_mode;
 965                         sha = b_sha;
 966                         conf = "directory/file";
 967                 }
 968                 if (path_list_has_path(&current_directory_set, path)) {
 969                         const char *new_path = unique_path(path, add_branch);
 970                         clean_merge = 0;
 971                         output("CONFLICT (%s): There is a directory with name %s in %s. "
 972                                "Adding %s as %s",
 973                                conf, path, other_branch, path, new_path);
 974                         remove_file(0, path, 0);
 975                         update_file(0, sha, mode, new_path);
 976                 } else {
 977                         output("Adding %s", path);
 978                         update_file(1, sha, mode, path);
 979                 }
 980         } else if (a_sha && b_sha) {
 981                 /* Case C: Added in both (check for same permissions) and */
 982                 /* case D: Modified in both, but differently. */
 983                 const char *reason = "content";
 984                 struct merge_file_info mfi;
 985                 struct diff_filespec o, a, b;
 986
 987                 if (!o_sha) {
 988                         reason = "add/add";
 989                         o_sha = (unsigned char *)null_sha1;
 990                 }
 991                 output("Auto-merging %s", path);
 992                 o.path = a.path = b.path = (char *)path;
 993                 hashcpy(o.sha1, o_sha);
 994                 o.mode = o_mode;
 995                 hashcpy(a.sha1, a_sha);
 996                 a.mode = a_mode;
 997                 hashcpy(b.sha1, b_sha);
 998                 b.mode = b_mode;
 999
1000                 mfi = merge_file(&o, &a, &b,
1001                                  branch1, branch2);
1002
1003                 if (mfi.clean)
1004                         update_file(1, mfi.sha, mfi.mode, path);
1005                 else {
1006                         clean_merge = 0;
1007                         output("CONFLICT (%s): Merge conflict in %s",
1008                                         reason, path);
1009
1010                         if (index_only)
1011                                 update_file(0, mfi.sha, mfi.mode, path);
1012                         else
1013                                 update_file_flags(mfi.sha, mfi.mode, path,
1014                                               0 /* update_cache */, 1 /* update_working_directory */);
1015                 }
1016         } else
1017                 die("Fatal merge failure, shouldn't happen.");
1018
1019         return clean_merge;
1020 }
1021
1022 static int merge_trees(struct tree *head,
1023                        struct tree *merge,
1024                        struct tree *common,
1025                        const char *branch1,
1026                        const char *branch2,
1027                        struct tree **result)
1028 {
1029         int code, clean;
1030         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1031                 output("Already uptodate!");
1032                 *result = head;
1033                 return 1;
1034         }
1035
1036         code = git_merge_trees(index_only, common, head, merge);
1037
1038         if (code != 0)
1039                 die("merging of trees %s and %s failed",
1040                     sha1_to_hex(head->object.sha1),
1041                     sha1_to_hex(merge->object.sha1));
1042
1043         if (unmerged_index()) {
1044                 struct path_list *entries, *re_head, *re_merge;
1045                 int i;
1046                 path_list_clear(&current_file_set, 1);
1047                 path_list_clear(&current_directory_set, 1);
1048                 get_files_dirs(head);
1049                 get_files_dirs(merge);
1050
1051                 entries = get_unmerged();
1052                 re_head  = get_renames(head, common, head, merge, entries);
1053                 re_merge = get_renames(merge, common, head, merge, entries);
1054                 clean = process_renames(re_head, re_merge,
1055                                 branch1, branch2);
1056                 for (i = 0; i < entries->nr; i++) {
1057                         const char *path = entries->items[i].path;
1058                         struct stage_data *e = entries->items[i].util;
1059                         if (e->processed)
1060                                 continue;
1061                         if (!process_entry(path, e, branch1, branch2))
1062                                 clean = 0;
1063                 }
1064
1065                 path_list_clear(re_merge, 0);
1066                 path_list_clear(re_head, 0);
1067                 path_list_clear(entries, 1);
1068
1069         }
1070         else
1071                 clean = 1;
1072
1073         if (index_only)
1074                 *result = git_write_tree();
1075
1076         return clean;
1077 }
1078
1079 static struct commit_list *reverse_commit_list(struct commit_list *list)
1080 {
1081         struct commit_list *next = NULL, *current, *backup;
1082         for (current = list; current; current = backup) {
1083                 backup = current->next;
1084                 current->next = next;
1085                 next = current;
1086         }
1087         return next;
1088 }
1089
1090 /*
1091  * Merge the commits h1 and h2, return the resulting virtual
1092  * commit object and a flag indicating the cleaness of the merge.
1093  */
1094 static int merge(struct commit *h1,
1095                  struct commit *h2,
1096                  const char *branch1,
1097                  const char *branch2,
1098                  int call_depth /* =0 */,
1099                  struct commit_list *ca,
1100                  struct commit **result)
1101 {
1102         struct commit_list *iter;
1103         struct commit *merged_common_ancestors;
1104         struct tree *mrtree;
1105         int clean;
1106
1107         output("Merging:");
1108         output_commit_title(h1);
1109         output_commit_title(h2);
1110
1111         if (!ca) {
1112                 ca = get_merge_bases(h1, h2, 1);
1113                 ca = reverse_commit_list(ca);
1114         }
1115
1116         output("found %u common ancestor(s):", commit_list_count(ca));
1117         for (iter = ca; iter; iter = iter->next)
1118                 output_commit_title(iter->item);
1119
1120         merged_common_ancestors = pop_commit(&ca);
1121         if (merged_common_ancestors == NULL) {
1122                 /* if there is no common ancestor, make an empty tree */
1123                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1124
1125                 tree->object.parsed = 1;
1126                 tree->object.type = OBJ_TREE;
1127                 write_sha1_file(NULL, 0, tree_type, tree->object.sha1);
1128                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1129         }
1130
1131         for (iter = ca; iter; iter = iter->next) {
1132                 output_indent = call_depth + 1;
1133                 /*
1134                  * When the merge fails, the result contains files
1135                  * with conflict markers. The cleanness flag is
1136                  * ignored, it was never acutally used, as result of
1137                  * merge_trees has always overwritten it: the commited
1138                  * "conflicts" were already resolved.
1139                  */
1140                 discard_cache();
1141                 merge(merged_common_ancestors, iter->item,
1142                       "Temporary merge branch 1",
1143                       "Temporary merge branch 2",
1144                       call_depth + 1,
1145                       NULL,
1146                       &merged_common_ancestors);
1147                 output_indent = call_depth;
1148
1149                 if (!merged_common_ancestors)
1150                         die("merge returned no commit");
1151         }
1152
1153         discard_cache();
1154         if (call_depth == 0) {
1155                 read_cache();
1156                 index_only = 0;
1157         } else
1158                 index_only = 1;
1159
1160         clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
1161                             branch1, branch2, &mrtree);
1162
1163         if (index_only) {
1164                 *result = make_virtual_commit(mrtree, "merged tree");
1165                 commit_list_insert(h1, &(*result)->parents);
1166                 commit_list_insert(h2, &(*result)->parents->next);
1167         }
1168         return clean;
1169 }
1170
1171 static const char *better_branch_name(const char *branch)
1172 {
1173         static char githead_env[8 + 40 + 1];
1174         char *name;
1175
1176         if (strlen(branch) != 40)
1177                 return branch;
1178         sprintf(githead_env, "GITHEAD_%s", branch);
1179         name = getenv(githead_env);
1180         return name ? name : branch;
1181 }
1182
1183 static struct commit *get_ref(const char *ref)
1184 {
1185         unsigned char sha1[20];
1186         struct object *object;
1187
1188         if (get_sha1(ref, sha1))
1189                 die("Could not resolve ref '%s'", ref);
1190         object = deref_tag(parse_object(sha1), ref, strlen(ref));
1191         if (object->type == OBJ_TREE)
1192                 return make_virtual_commit((struct tree*)object,
1193                         better_branch_name(ref));
1194         if (object->type != OBJ_COMMIT)
1195                 return NULL;
1196         if (parse_commit((struct commit *)object))
1197                 die("Could not parse commit '%s'", sha1_to_hex(object->sha1));
1198         return (struct commit *)object;
1199 }
1200
1201 int main(int argc, char *argv[])
1202 {
1203         static const char *bases[20];
1204         static unsigned bases_count = 0;
1205         int i, clean;
1206         const char *branch1, *branch2;
1207         struct commit *result, *h1, *h2;
1208         struct commit_list *ca = NULL;
1209         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1210         int index_fd;
1211
1212         git_config(git_default_config); /* core.filemode */
1213
1214         if (argc < 4)
1215                 die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
1216
1217         for (i = 1; i < argc; ++i) {
1218                 if (!strcmp(argv[i], "--"))
1219                         break;
1220                 if (bases_count < sizeof(bases)/sizeof(*bases))
1221                         bases[bases_count++] = argv[i];
1222         }
1223         if (argc - i != 3) /* "--" "<head>" "<remote>" */
1224                 die("Not handling anything other than two heads merge.");
1225
1226         branch1 = argv[++i];
1227         branch2 = argv[++i];
1228
1229         h1 = get_ref(branch1);
1230         h2 = get_ref(branch2);
1231
1232         branch1 = better_branch_name(branch1);
1233         branch2 = better_branch_name(branch2);
1234         printf("Merging %s with %s\n", branch1, branch2);
1235
1236         index_fd = hold_lock_file_for_update(lock, get_index_file(), 1);
1237
1238         for (i = 0; i < bases_count; i++) {
1239                 struct commit *ancestor = get_ref(bases[i]);
1240                 ca = commit_list_insert(ancestor, &ca);
1241         }
1242         clean = merge(h1, h2, branch1, branch2, 0, ca, &result);
1243
1244         if (active_cache_changed &&
1245             (write_cache(index_fd, active_cache, active_nr) ||
1246              close(index_fd) || commit_lock_file(lock)))
1247                         die ("unable to write %s", get_index_file());
1248
1249         return clean ? 0: 1;
1250 }