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

   1 /*
   2  * Recursive Merge algorithm stolen from git-merge-recursive.py by
   3  * Fredrik Kuivinen.
   4  * The thieves were Alex Riesen and Johannes Schindelin, in June/July 2006
   5  */
   6 #include "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 #include "interpolate.h"
  19 #include "attr.h"
  20
  21 static int subtree_merge;
  22
  23 static struct tree *shift_tree_object(struct tree *one, struct tree *two)
  24 {
  25         unsigned char shifted[20];
  26
  27         /*
  28          * NEEDSWORK: this limits the recursion depth to hardcoded
  29          * value '2' to avoid excessive overhead.
  30          */
  31         shift_tree(one->object.sha1, two->object.sha1, shifted, 2);
  32         if (!hashcmp(two->object.sha1, shifted))
  33                 return two;
  34         return lookup_tree(shifted);
  35 }
  36
  37 /*
  38  * A virtual commit has
  39  * - (const char *)commit->util set to the name, and
  40  * - *(int *)commit->object.sha1 set to the virtual id.
  41  */
  42
  43 static unsigned commit_list_count(const struct commit_list *l)
  44 {
  45         unsigned c = 0;
  46         for (; l; l = l->next )
  47                 c++;
  48         return c;
  49 }
  50
  51 static struct commit *make_virtual_commit(struct tree *tree, const char *comment)
  52 {
  53         struct commit *commit = xcalloc(1, sizeof(struct commit));
  54         static unsigned virtual_id = 1;
  55         commit->tree = tree;
  56         commit->util = (void*)comment;
  57         *(int*)commit->object.sha1 = virtual_id++;
  58         /* avoid warnings */
  59         commit->object.parsed = 1;
  60         return commit;
  61 }
  62
  63 /*
  64  * Since we use get_tree_entry(), which does not put the read object into
  65  * the object pool, we cannot rely on a == b.
  66  */
  67 static int sha_eq(const unsigned char *a, const unsigned char *b)
  68 {
  69         if (!a && !b)
  70                 return 2;
  71         return a && b && hashcmp(a, b) == 0;
  72 }
  73
  74 /*
  75  * Since we want to write the index eventually, we cannot reuse the index
  76  * for these (temporary) data.
  77  */
  78 struct stage_data
  79 {
  80         struct
  81         {
  82                 unsigned mode;
  83                 unsigned char sha[20];
  84         } stages[4];
  85         unsigned processed:1;
  86 };
  87
  88 static struct path_list current_file_set = {NULL, 0, 0, 1};
  89 static struct path_list current_directory_set = {NULL, 0, 0, 1};
  90
  91 static int call_depth = 0;
  92 static int verbosity = 2;
  93 static int rename_limit = -1;
  94 static int buffer_output = 1;
  95 static struct strbuf obuf = STRBUF_INIT;
  96
  97 static int show(int v)
  98 {
  99         return (!call_depth && verbosity >= v) || verbosity >= 5;
 100 }
 101
 102 static void flush_output(void)
 103 {
 104         if (obuf.len) {
 105                 fputs(obuf.buf, stdout);
 106                 strbuf_reset(&obuf);
 107         }
 108 }
 109
 110 static void output(int v, const char *fmt, ...)
 111 {
 112         int len;
 113         va_list ap;
 114
 115         if (!show(v))
 116                 return;
 117
 118         strbuf_grow(&obuf, call_depth * 2 + 2);
 119         memset(obuf.buf + obuf.len, ' ', call_depth * 2);
 120         strbuf_setlen(&obuf, obuf.len + call_depth * 2);
 121
 122         va_start(ap, fmt);
 123         len = vsnprintf(obuf.buf + obuf.len, strbuf_avail(&obuf), fmt, ap);
 124         va_end(ap);
 125
 126         if (len < 0)
 127                 len = 0;
 128         if (len >= strbuf_avail(&obuf)) {
 129                 strbuf_grow(&obuf, len + 2);
 130                 va_start(ap, fmt);
 131                 len = vsnprintf(obuf.buf + obuf.len, strbuf_avail(&obuf), fmt, ap);
 132                 va_end(ap);
 133                 if (len >= strbuf_avail(&obuf)) {
 134                         die("this should not happen, your snprintf is broken");
 135                 }
 136         }
 137         strbuf_setlen(&obuf, obuf.len + len);
 138         strbuf_add(&obuf, "\n", 1);
 139         if (!buffer_output)
 140                 flush_output();
 141 }
 142
 143 static void output_commit_title(struct commit *commit)
 144 {
 145         int i;
 146         flush_output();
 147         for (i = call_depth; i--;)
 148                 fputs("  ", stdout);
 149         if (commit->util)
 150                 printf("virtual %s\n", (char *)commit->util);
 151         else {
 152                 printf("%s ", find_unique_abbrev(commit->object.sha1, DEFAULT_ABBREV));
 153                 if (parse_commit(commit) != 0)
 154                         printf("(bad commit)\n");
 155                 else {
 156                         const char *s;
 157                         int len;
 158                         for (s = commit->buffer; *s; s++)
 159                                 if (*s == '\n' && s[1] == '\n') {
 160                                         s += 2;
 161                                         break;
 162                                 }
 163                         for (len = 0; s[len] && '\n' != s[len]; len++)
 164                                 ; /* do nothing */
 165                         printf("%.*s\n", len, s);
 166                 }
 167         }
 168 }
 169
 170 static int add_cacheinfo(unsigned int mode, const unsigned char *sha1,
 171                 const char *path, int stage, int refresh, int options)
 172 {
 173         struct cache_entry *ce;
 174         ce = make_cache_entry(mode, sha1 ? sha1 : null_sha1, path, stage, refresh);
 175         if (!ce)
 176                 return error("addinfo_cache failed for path '%s'", path);
 177         return add_cache_entry(ce, options);
 178 }
 179
 180 /*
 181  * This is a global variable which is used in a number of places but
 182  * only written to in the 'merge' function.
 183  *
 184  * index_only == 1    => Don't leave any non-stage 0 entries in the cache and
 185  *                       don't update the working directory.
 186  *               0    => Leave unmerged entries in the cache and update
 187  *                       the working directory.
 188  */
 189 static int index_only = 0;
 190
 191 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 192 {
 193         parse_tree(tree);
 194         init_tree_desc(desc, tree->buffer, tree->size);
 195 }
 196
 197 static int git_merge_trees(int index_only,
 198                            struct tree *common,
 199                            struct tree *head,
 200                            struct tree *merge)
 201 {
 202         int rc;
 203         struct tree_desc t[3];
 204         struct unpack_trees_options opts;
 205
 206         memset(&opts, 0, sizeof(opts));
 207         if (index_only)
 208                 opts.index_only = 1;
 209         else
 210                 opts.update = 1;
 211         opts.merge = 1;
 212         opts.head_idx = 2;
 213         opts.fn = threeway_merge;
 214
 215         init_tree_desc_from_tree(t+0, common);
 216         init_tree_desc_from_tree(t+1, head);
 217         init_tree_desc_from_tree(t+2, merge);
 218
 219         rc = unpack_trees(3, t, &opts);
 220         cache_tree_free(&active_cache_tree);
 221         return rc;
 222 }
 223
 224 static int unmerged_index(void)
 225 {
 226         int i;
 227         for (i = 0; i < active_nr; i++) {
 228                 struct cache_entry *ce = active_cache[i];
 229                 if (ce_stage(ce))
 230                         return 1;
 231         }
 232         return 0;
 233 }
 234
 235 static struct tree *git_write_tree(void)
 236 {
 237         struct tree *result = NULL;
 238
 239         if (unmerged_index()) {
 240                 int i;
 241                 output(0, "There are unmerged index entries:");
 242                 for (i = 0; i < active_nr; i++) {
 243                         struct cache_entry *ce = active_cache[i];
 244                         if (ce_stage(ce))
 245                                 output(0, "%d %.*s", ce_stage(ce), ce_namelen(ce), ce->name);
 246                 }
 247                 return NULL;
 248         }
 249
 250         if (!active_cache_tree)
 251                 active_cache_tree = cache_tree();
 252
 253         if (!cache_tree_fully_valid(active_cache_tree) &&
 254             cache_tree_update(active_cache_tree,
 255                               active_cache, active_nr, 0, 0) < 0)
 256                 die("error building trees");
 257
 258         result = lookup_tree(active_cache_tree->sha1);
 259
 260         return result;
 261 }
 262
 263 static int save_files_dirs(const unsigned char *sha1,
 264                 const char *base, int baselen, const char *path,
 265                 unsigned int mode, int stage)
 266 {
 267         int len = strlen(path);
 268         char *newpath = xmalloc(baselen + len + 1);
 269         memcpy(newpath, base, baselen);
 270         memcpy(newpath + baselen, path, len);
 271         newpath[baselen + len] = '\0';
 272
 273         if (S_ISDIR(mode))
 274                 path_list_insert(newpath, &current_directory_set);
 275         else
 276                 path_list_insert(newpath, &current_file_set);
 277         free(newpath);
 278
 279         return READ_TREE_RECURSIVE;
 280 }
 281
 282 static int get_files_dirs(struct tree *tree)
 283 {
 284         int n;
 285         if (read_tree_recursive(tree, "", 0, 0, NULL, save_files_dirs) != 0)
 286                 return 0;
 287         n = current_file_set.nr + current_directory_set.nr;
 288         return n;
 289 }
 290
 291 /*
 292  * Returns an index_entry instance which doesn't have to correspond to
 293  * a real cache entry in Git's index.
 294  */
 295 static struct stage_data *insert_stage_data(const char *path,
 296                 struct tree *o, struct tree *a, struct tree *b,
 297                 struct path_list *entries)
 298 {
 299         struct path_list_item *item;
 300         struct stage_data *e = xcalloc(1, sizeof(struct stage_data));
 301         get_tree_entry(o->object.sha1, path,
 302                         e->stages[1].sha, &e->stages[1].mode);
 303         get_tree_entry(a->object.sha1, path,
 304                         e->stages[2].sha, &e->stages[2].mode);
 305         get_tree_entry(b->object.sha1, path,
 306                         e->stages[3].sha, &e->stages[3].mode);
 307         item = path_list_insert(path, entries);
 308         item->util = e;
 309         return e;
 310 }
 311
 312 /*
 313  * Create a dictionary mapping file names to stage_data objects. The
 314  * dictionary contains one entry for every path with a non-zero stage entry.
 315  */
 316 static struct path_list *get_unmerged(void)
 317 {
 318         struct path_list *unmerged = xcalloc(1, sizeof(struct path_list));
 319         int i;
 320
 321         unmerged->strdup_paths = 1;
 322
 323         for (i = 0; i < active_nr; i++) {
 324                 struct path_list_item *item;
 325                 struct stage_data *e;
 326                 struct cache_entry *ce = active_cache[i];
 327                 if (!ce_stage(ce))
 328                         continue;
 329
 330                 item = path_list_lookup(ce->name, unmerged);
 331                 if (!item) {
 332                         item = path_list_insert(ce->name, unmerged);
 333                         item->util = xcalloc(1, sizeof(struct stage_data));
 334                 }
 335                 e = item->util;
 336                 e->stages[ce_stage(ce)].mode = ntohl(ce->ce_mode);
 337                 hashcpy(e->stages[ce_stage(ce)].sha, ce->sha1);
 338         }
 339
 340         return unmerged;
 341 }
 342
 343 struct rename
 344 {
 345         struct diff_filepair *pair;
 346         struct stage_data *src_entry;
 347         struct stage_data *dst_entry;
 348         unsigned processed:1;
 349 };
 350
 351 /*
 352  * Get information of all renames which occurred between 'o_tree' and
 353  * 'tree'. We need the three trees in the merge ('o_tree', 'a_tree' and
 354  * 'b_tree') to be able to associate the correct cache entries with
 355  * the rename information. 'tree' is always equal to either a_tree or b_tree.
 356  */
 357 static struct path_list *get_renames(struct tree *tree,
 358                                         struct tree *o_tree,
 359                                         struct tree *a_tree,
 360                                         struct tree *b_tree,
 361                                         struct path_list *entries)
 362 {
 363         int i;
 364         struct path_list *renames;
 365         struct diff_options opts;
 366
 367         renames = xcalloc(1, sizeof(struct path_list));
 368         diff_setup(&opts);
 369         DIFF_OPT_SET(&opts, RECURSIVE);
 370         opts.detect_rename = DIFF_DETECT_RENAME;
 371         opts.rename_limit = rename_limit;
 372         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 373         if (diff_setup_done(&opts) < 0)
 374                 die("diff setup failed");
 375         diff_tree_sha1(o_tree->object.sha1, tree->object.sha1, "", &opts);
 376         diffcore_std(&opts);
 377         for (i = 0; i < diff_queued_diff.nr; ++i) {
 378                 struct path_list_item *item;
 379                 struct rename *re;
 380                 struct diff_filepair *pair = diff_queued_diff.queue[i];
 381                 if (pair->status != 'R') {
 382                         diff_free_filepair(pair);
 383                         continue;
 384                 }
 385                 re = xmalloc(sizeof(*re));
 386                 re->processed = 0;
 387                 re->pair = pair;
 388                 item = path_list_lookup(re->pair->one->path, entries);
 389                 if (!item)
 390                         re->src_entry = insert_stage_data(re->pair->one->path,
 391                                         o_tree, a_tree, b_tree, entries);
 392                 else
 393                         re->src_entry = item->util;
 394
 395                 item = path_list_lookup(re->pair->two->path, entries);
 396                 if (!item)
 397                         re->dst_entry = insert_stage_data(re->pair->two->path,
 398                                         o_tree, a_tree, b_tree, entries);
 399                 else
 400                         re->dst_entry = item->util;
 401                 item = path_list_insert(pair->one->path, renames);
 402                 item->util = re;
 403         }
 404         opts.output_format = DIFF_FORMAT_NO_OUTPUT;
 405         diff_queued_diff.nr = 0;
 406         diff_flush(&opts);
 407         return renames;
 408 }
 409
 410 static int update_stages(const char *path, struct diff_filespec *o,
 411                          struct diff_filespec *a, struct diff_filespec *b,
 412                          int clear)
 413 {
 414         int options = ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE;
 415         if (clear)
 416                 if (remove_file_from_cache(path))
 417                         return -1;
 418         if (o)
 419                 if (add_cacheinfo(o->mode, o->sha1, path, 1, 0, options))
 420                         return -1;
 421         if (a)
 422                 if (add_cacheinfo(a->mode, a->sha1, path, 2, 0, options))
 423                         return -1;
 424         if (b)
 425                 if (add_cacheinfo(b->mode, b->sha1, path, 3, 0, options))
 426                         return -1;
 427         return 0;
 428 }
 429
 430 static int remove_path(const char *name)
 431 {
 432         int ret;
 433         char *slash, *dirs;
 434
 435         ret = unlink(name);
 436         if (ret)
 437                 return ret;
 438         dirs = xstrdup(name);
 439         while ((slash = strrchr(name, '/'))) {
 440                 *slash = '\0';
 441                 if (rmdir(name) != 0)
 442                         break;
 443         }
 444         free(dirs);
 445         return ret;
 446 }
 447
 448 static int remove_file(int clean, const char *path, int no_wd)
 449 {
 450         int update_cache = index_only || clean;
 451         int update_working_directory = !index_only && !no_wd;
 452
 453         if (update_cache) {
 454                 if (remove_file_from_cache(path))
 455                         return -1;
 456         }
 457         if (update_working_directory) {
 458                 unlink(path);
 459                 if (errno != ENOENT || errno != EISDIR)
 460                         return -1;
 461                 remove_path(path);
 462         }
 463         return 0;
 464 }
 465
 466 static char *unique_path(const char *path, const char *branch)
 467 {
 468         char *newpath = xmalloc(strlen(path) + 1 + strlen(branch) + 8 + 1);
 469         int suffix = 0;
 470         struct stat st;
 471         char *p = newpath + strlen(path);
 472         strcpy(newpath, path);
 473         *(p++) = '~';
 474         strcpy(p, branch);
 475         for (; *p; ++p)
 476                 if ('/' == *p)
 477                         *p = '_';
 478         while (path_list_has_path(&current_file_set, newpath) ||
 479                path_list_has_path(&current_directory_set, newpath) ||
 480                lstat(newpath, &st) == 0)
 481                 sprintf(p, "_%d", suffix++);
 482
 483         path_list_insert(newpath, &current_file_set);
 484         return newpath;
 485 }
 486
 487 static int mkdir_p(const char *path, unsigned long mode)
 488 {
 489         /* path points to cache entries, so xstrdup before messing with it */
 490         char *buf = xstrdup(path);
 491         int result = safe_create_leading_directories(buf);
 492         free(buf);
 493         return result;
 494 }
 495
 496 static void flush_buffer(int fd, const char *buf, unsigned long size)
 497 {
 498         while (size > 0) {
 499                 long ret = write_in_full(fd, buf, size);
 500                 if (ret < 0) {
 501                         /* Ignore epipe */
 502                         if (errno == EPIPE)
 503                                 break;
 504                         die("merge-recursive: %s", strerror(errno));
 505                 } else if (!ret) {
 506                         die("merge-recursive: disk full?");
 507                 }
 508                 size -= ret;
 509                 buf += ret;
 510         }
 511 }
 512
 513 static int make_room_for_path(const char *path)
 514 {
 515         int status;
 516         const char *msg = "failed to create path '%s'%s";
 517
 518         status = mkdir_p(path, 0777);
 519         if (status) {
 520                 if (status == -3) {
 521                         /* something else exists */
 522                         error(msg, path, ": perhaps a D/F conflict?");
 523                         return -1;
 524                 }
 525                 die(msg, path, "");
 526         }
 527
 528         /* Successful unlink is good.. */
 529         if (!unlink(path))
 530                 return 0;
 531         /* .. and so is no existing file */
 532         if (errno == ENOENT)
 533                 return 0;
 534         /* .. but not some other error (who really cares what?) */
 535         return error(msg, path, ": perhaps a D/F conflict?");
 536 }
 537
 538 static void update_file_flags(const unsigned char *sha,
 539                               unsigned mode,
 540                               const char *path,
 541                               int update_cache,
 542                               int update_wd)
 543 {
 544         if (index_only)
 545                 update_wd = 0;
 546
 547         if (update_wd) {
 548                 enum object_type type;
 549                 void *buf;
 550                 unsigned long size;
 551
 552                 if (S_ISGITLINK(mode))
 553                         die("cannot read object %s '%s': It is a submodule!",
 554                             sha1_to_hex(sha), path);
 555
 556                 buf = read_sha1_file(sha, &type, &size);
 557                 if (!buf)
 558                         die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 559                 if (type != OBJ_BLOB)
 560                         die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 561
 562                 if (make_room_for_path(path) < 0) {
 563                         update_wd = 0;
 564                         goto update_index;
 565                 }
 566                 if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 567                         int fd;
 568                         if (mode & 0100)
 569                                 mode = 0777;
 570                         else
 571                                 mode = 0666;
 572                         fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 573                         if (fd < 0)
 574                                 die("failed to open %s: %s", path, strerror(errno));
 575                         flush_buffer(fd, buf, size);
 576                         close(fd);
 577                 } else if (S_ISLNK(mode)) {
 578                         char *lnk = xmemdupz(buf, size);
 579                         mkdir_p(path, 0777);
 580                         unlink(path);
 581                         symlink(lnk, path);
 582                         free(lnk);
 583                 } else
 584                         die("do not know what to do with %06o %s '%s'",
 585                             mode, sha1_to_hex(sha), path);
 586         }
 587  update_index:
 588         if (update_cache)
 589                 add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 590 }
 591
 592 static void update_file(int clean,
 593                         const unsigned char *sha,
 594                         unsigned mode,
 595                         const char *path)
 596 {
 597         update_file_flags(sha, mode, path, index_only || clean, !index_only);
 598 }
 599
 600 /* Low level file merging, update and removal */
 601
 602 struct merge_file_info
 603 {
 604         unsigned char sha[20];
 605         unsigned mode;
 606         unsigned clean:1,
 607                  merge:1;
 608 };
 609
 610 static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 611 {
 612         unsigned long size;
 613         enum object_type type;
 614
 615         if (!hashcmp(sha1, null_sha1)) {
 616                 mm->ptr = xstrdup("");
 617                 mm->size = 0;
 618                 return;
 619         }
 620
 621         mm->ptr = read_sha1_file(sha1, &type, &size);
 622         if (!mm->ptr || type != OBJ_BLOB)
 623                 die("unable to read blob object %s", sha1_to_hex(sha1));
 624         mm->size = size;
 625 }
 626
 627 /*
 628  * Customizable low-level merge drivers support.
 629  */
 630
 631 struct ll_merge_driver;
 632 typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
 633                            const char *path,
 634                            mmfile_t *orig,
 635                            mmfile_t *src1, const char *name1,
 636                            mmfile_t *src2, const char *name2,
 637                            mmbuffer_t *result);
 638
 639 struct ll_merge_driver {
 640         const char *name;
 641         const char *description;
 642         ll_merge_fn fn;
 643         const char *recursive;
 644         struct ll_merge_driver *next;
 645         char *cmdline;
 646 };
 647
 648 /*
 649  * Built-in low-levels
 650  */
 651 static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 652                            const char *path_unused,
 653                            mmfile_t *orig,
 654                            mmfile_t *src1, const char *name1,
 655                            mmfile_t *src2, const char *name2,
 656                            mmbuffer_t *result)
 657 {
 658         /*
 659          * The tentative merge result is "ours" for the final round,
 660          * or common ancestor for an internal merge.  Still return
 661          * "conflicted merge" status.
 662          */
 663         mmfile_t *stolen = index_only ? orig : src1;
 664
 665         result->ptr = stolen->ptr;
 666         result->size = stolen->size;
 667         stolen->ptr = NULL;
 668         return 1;
 669 }
 670
 671 static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 672                         const char *path_unused,
 673                         mmfile_t *orig,
 674                         mmfile_t *src1, const char *name1,
 675                         mmfile_t *src2, const char *name2,
 676                         mmbuffer_t *result)
 677 {
 678         xpparam_t xpp;
 679
 680         if (buffer_is_binary(orig->ptr, orig->size) ||
 681             buffer_is_binary(src1->ptr, src1->size) ||
 682             buffer_is_binary(src2->ptr, src2->size)) {
 683                 warning("Cannot merge binary files: %s vs. %s\n",
 684                         name1, name2);
 685                 return ll_binary_merge(drv_unused, path_unused,
 686                                        orig, src1, name1,
 687                                        src2, name2,
 688                                        result);
 689         }
 690
 691         memset(&xpp, 0, sizeof(xpp));
 692         return xdl_merge(orig,
 693                          src1, name1,
 694                          src2, name2,
 695                          &xpp, XDL_MERGE_ZEALOUS,
 696                          result);
 697 }
 698
 699 static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 700                           const char *path_unused,
 701                           mmfile_t *orig,
 702                           mmfile_t *src1, const char *name1,
 703                           mmfile_t *src2, const char *name2,
 704                           mmbuffer_t *result)
 705 {
 706         char *src, *dst;
 707         long size;
 708         const int marker_size = 7;
 709
 710         int status = ll_xdl_merge(drv_unused, path_unused,
 711                                   orig, src1, NULL, src2, NULL, result);
 712         if (status <= 0)
 713                 return status;
 714         size = result->size;
 715         src = dst = result->ptr;
 716         while (size) {
 717                 char ch;
 718                 if ((marker_size < size) &&
 719                     (*src == '<' || *src == '=' || *src == '>')) {
 720                         int i;
 721                         ch = *src;
 722                         for (i = 0; i < marker_size; i++)
 723                                 if (src[i] != ch)
 724                                         goto not_a_marker;
 725                         if (src[marker_size] != '\n')
 726                                 goto not_a_marker;
 727                         src += marker_size + 1;
 728                         size -= marker_size + 1;
 729                         continue;
 730                 }
 731         not_a_marker:
 732                 do {
 733                         ch = *src++;
 734                         *dst++ = ch;
 735                         size--;
 736                 } while (ch != '\n' && size);
 737         }
 738         result->size = dst - result->ptr;
 739         return 0;
 740 }
 741
 742 #define LL_BINARY_MERGE 0
 743 #define LL_TEXT_MERGE 1
 744 #define LL_UNION_MERGE 2
 745 static struct ll_merge_driver ll_merge_drv[] = {
 746         { "binary", "built-in binary merge", ll_binary_merge },
 747         { "text", "built-in 3-way text merge", ll_xdl_merge },
 748         { "union", "built-in union merge", ll_union_merge },
 749 };
 750
 751 static void create_temp(mmfile_t *src, char *path)
 752 {
 753         int fd;
 754
 755         strcpy(path, ".merge_file_XXXXXX");
 756         fd = xmkstemp(path);
 757         if (write_in_full(fd, src->ptr, src->size) != src->size)
 758                 die("unable to write temp-file");
 759         close(fd);
 760 }
 761
 762 /*
 763  * User defined low-level merge driver support.
 764  */
 765 static int ll_ext_merge(const struct ll_merge_driver *fn,
 766                         const char *path,
 767                         mmfile_t *orig,
 768                         mmfile_t *src1, const char *name1,
 769                         mmfile_t *src2, const char *name2,
 770                         mmbuffer_t *result)
 771 {
 772         char temp[3][50];
 773         char cmdbuf[2048];
 774         struct interp table[] = {
 775                 { "%O" },
 776                 { "%A" },
 777                 { "%B" },
 778         };
 779         struct child_process child;
 780         const char *args[20];
 781         int status, fd, i;
 782         struct stat st;
 783
 784         if (fn->cmdline == NULL)
 785                 die("custom merge driver %s lacks command line.", fn->name);
 786
 787         result->ptr = NULL;
 788         result->size = 0;
 789         create_temp(orig, temp[0]);
 790         create_temp(src1, temp[1]);
 791         create_temp(src2, temp[2]);
 792
 793         interp_set_entry(table, 0, temp[0]);
 794         interp_set_entry(table, 1, temp[1]);
 795         interp_set_entry(table, 2, temp[2]);
 796
 797         output(1, "merging %s using %s", path,
 798                fn->description ? fn->description : fn->name);
 799
 800         interpolate(cmdbuf, sizeof(cmdbuf), fn->cmdline, table, 3);
 801
 802         memset(&child, 0, sizeof(child));
 803         child.argv = args;
 804         args[0] = "sh";
 805         args[1] = "-c";
 806         args[2] = cmdbuf;
 807         args[3] = NULL;
 808
 809         status = run_command(&child);
 810         if (status < -ERR_RUN_COMMAND_FORK)
 811                 ; /* failure in run-command */
 812         else
 813                 status = -status;
 814         fd = open(temp[1], O_RDONLY);
 815         if (fd < 0)
 816                 goto bad;
 817         if (fstat(fd, &st))
 818                 goto close_bad;
 819         result->size = st.st_size;
 820         result->ptr = xmalloc(result->size + 1);
 821         if (read_in_full(fd, result->ptr, result->size) != result->size) {
 822                 free(result->ptr);
 823                 result->ptr = NULL;
 824                 result->size = 0;
 825         }
 826  close_bad:
 827         close(fd);
 828  bad:
 829         for (i = 0; i < 3; i++)
 830                 unlink(temp[i]);
 831         return status;
 832 }
 833
 834 /*
 835  * merge.default and merge.driver configuration items
 836  */
 837 static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 838 static const char *default_ll_merge;
 839
 840 static int read_merge_config(const char *var, const char *value)
 841 {
 842         struct ll_merge_driver *fn;
 843         const char *ep, *name;
 844         int namelen;
 845
 846         if (!strcmp(var, "merge.default")) {
 847                 if (!value)
 848                         return config_error_nonbool(var);
 849                 default_ll_merge = strdup(value);
 850                 return 0;
 851         }
 852
 853         /*
 854          * We are not interested in anything but "merge.<name>.variable";
 855          * especially, we do not want to look at variables such as
 856          * "merge.summary", "merge.tool", and "merge.verbosity".
 857          */
 858         if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
 859                 return 0;
 860
 861         /*
 862          * Find existing one as we might be processing merge.<name>.var2
 863          * after seeing merge.<name>.var1.
 864          */
 865         name = var + 6;
 866         namelen = ep - name;
 867         for (fn = ll_user_merge; fn; fn = fn->next)
 868                 if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 869                         break;
 870         if (!fn) {
 871                 fn = xcalloc(1, sizeof(struct ll_merge_driver));
 872                 fn->name = xmemdupz(name, namelen);
 873                 fn->fn = ll_ext_merge;
 874                 *ll_user_merge_tail = fn;
 875                 ll_user_merge_tail = &(fn->next);
 876         }
 877
 878         ep++;
 879
 880         if (!strcmp("name", ep)) {
 881                 if (!value)
 882                         return config_error_nonbool(var);
 883                 fn->description = strdup(value);
 884                 return 0;
 885         }
 886
 887         if (!strcmp("driver", ep)) {
 888                 if (!value)
 889                         return config_error_nonbool(var);
 890                 /*
 891                  * merge.<name>.driver specifies the command line:
 892                  *
 893                  *      command-line
 894                  *
 895                  * The command-line will be interpolated with the following
 896                  * tokens and is given to the shell:
 897                  *
 898                  *    %O - temporary file name for the merge base.
 899                  *    %A - temporary file name for our version.
 900                  *    %B - temporary file name for the other branches' version.
 901                  *
 902                  * The external merge driver should write the results in the
 903                  * file named by %A, and signal that it has done with zero exit
 904                  * status.
 905                  */
 906                 fn->cmdline = strdup(value);
 907                 return 0;
 908         }
 909
 910         if (!strcmp("recursive", ep)) {
 911                 if (!value)
 912                         return config_error_nonbool(var);
 913                 fn->recursive = strdup(value);
 914                 return 0;
 915         }
 916
 917         return 0;
 918 }
 919
 920 static void initialize_ll_merge(void)
 921 {
 922         if (ll_user_merge_tail)
 923                 return;
 924         ll_user_merge_tail = &ll_user_merge;
 925         git_config(read_merge_config);
 926 }
 927
 928 static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 929 {
 930         struct ll_merge_driver *fn;
 931         const char *name;
 932         int i;
 933
 934         initialize_ll_merge();
 935
 936         if (ATTR_TRUE(merge_attr))
 937                 return &ll_merge_drv[LL_TEXT_MERGE];
 938         else if (ATTR_FALSE(merge_attr))
 939                 return &ll_merge_drv[LL_BINARY_MERGE];
 940         else if (ATTR_UNSET(merge_attr)) {
 941                 if (!default_ll_merge)
 942                         return &ll_merge_drv[LL_TEXT_MERGE];
 943                 else
 944                         name = default_ll_merge;
 945         }
 946         else
 947                 name = merge_attr;
 948
 949         for (fn = ll_user_merge; fn; fn = fn->next)
 950                 if (!strcmp(fn->name, name))
 951                         return fn;
 952
 953         for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 954                 if (!strcmp(ll_merge_drv[i].name, name))
 955                         return &ll_merge_drv[i];
 956
 957         /* default to the 3-way */
 958         return &ll_merge_drv[LL_TEXT_MERGE];
 959 }
 960
 961 static const char *git_path_check_merge(const char *path)
 962 {
 963         static struct git_attr_check attr_merge_check;
 964
 965         if (!attr_merge_check.attr)
 966                 attr_merge_check.attr = git_attr("merge", 5);
 967
 968         if (git_checkattr(path, 1, &attr_merge_check))
 969                 return NULL;
 970         return attr_merge_check.value;
 971 }
 972
 973 static int ll_merge(mmbuffer_t *result_buf,
 974                     struct diff_filespec *o,
 975                     struct diff_filespec *a,
 976                     struct diff_filespec *b,
 977                     const char *branch1,
 978                     const char *branch2)
 979 {
 980         mmfile_t orig, src1, src2;
 981         char *name1, *name2;
 982         int merge_status;
 983         const char *ll_driver_name;
 984         const struct ll_merge_driver *driver;
 985
 986         name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 987         name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 988
 989         fill_mm(o->sha1, &orig);
 990         fill_mm(a->sha1, &src1);
 991         fill_mm(b->sha1, &src2);
 992
 993         ll_driver_name = git_path_check_merge(a->path);
 994         driver = find_ll_merge_driver(ll_driver_name);
 995
 996         if (index_only && driver->recursive)
 997                 driver = find_ll_merge_driver(driver->recursive);
 998         merge_status = driver->fn(driver, a->path,
 999                                   &orig, &src1, name1, &src2, name2,
1000                                   result_buf);
1001
1002         free(name1);
1003         free(name2);
1004         free(orig.ptr);
1005         free(src1.ptr);
1006         free(src2.ptr);
1007         return merge_status;
1008 }
1009
1010 static struct merge_file_info merge_file(struct diff_filespec *o,
1011                 struct diff_filespec *a, struct diff_filespec *b,
1012                 const char *branch1, const char *branch2)
1013 {
1014         struct merge_file_info result;
1015         result.merge = 0;
1016         result.clean = 1;
1017
1018         if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
1019                 result.clean = 0;
1020                 if (S_ISREG(a->mode)) {
1021                         result.mode = a->mode;
1022                         hashcpy(result.sha, a->sha1);
1023                 } else {
1024                         result.mode = b->mode;
1025                         hashcpy(result.sha, b->sha1);
1026                 }
1027         } else {
1028                 if (!sha_eq(a->sha1, o->sha1) && !sha_eq(b->sha1, o->sha1))
1029                         result.merge = 1;
1030
1031                 result.mode = a->mode == o->mode ? b->mode: a->mode;
1032
1033                 if (sha_eq(a->sha1, o->sha1))
1034                         hashcpy(result.sha, b->sha1);
1035                 else if (sha_eq(b->sha1, o->sha1))
1036                         hashcpy(result.sha, a->sha1);
1037                 else if (S_ISREG(a->mode)) {
1038                         mmbuffer_t result_buf;
1039                         int merge_status;
1040
1041                         merge_status = ll_merge(&result_buf, o, a, b,
1042                                                 branch1, branch2);
1043
1044                         if ((merge_status < 0) || !result_buf.ptr)
1045                                 die("Failed to execute internal merge");
1046
1047                         if (write_sha1_file(result_buf.ptr, result_buf.size,
1048                                             blob_type, result.sha))
1049                                 die("Unable to add %s to database",
1050                                     a->path);
1051
1052                         free(result_buf.ptr);
1053                         result.clean = (merge_status == 0);
1054                 } else if (S_ISGITLINK(a->mode)) {
1055                         result.clean = 0;
1056                         hashcpy(result.sha, a->sha1);
1057                 } else if (S_ISLNK(a->mode)) {
1058                         hashcpy(result.sha, a->sha1);
1059
1060                         if (!sha_eq(a->sha1, b->sha1))
1061                                 result.clean = 0;
1062                 } else {
1063                         die("unsupported object type in the tree");
1064                 }
1065         }
1066
1067         return result;
1068 }
1069
1070 static void conflict_rename_rename(struct rename *ren1,
1071                                    const char *branch1,
1072                                    struct rename *ren2,
1073                                    const char *branch2)
1074 {
1075         char *del[2];
1076         int delp = 0;
1077         const char *ren1_dst = ren1->pair->two->path;
1078         const char *ren2_dst = ren2->pair->two->path;
1079         const char *dst_name1 = ren1_dst;
1080         const char *dst_name2 = ren2_dst;
1081         if (path_list_has_path(&current_directory_set, ren1_dst)) {
1082                 dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
1083                 output(1, "%s is a directory in %s added as %s instead",
1084                        ren1_dst, branch2, dst_name1);
1085                 remove_file(0, ren1_dst, 0);
1086         }
1087         if (path_list_has_path(&current_directory_set, ren2_dst)) {
1088                 dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
1089                 output(1, "%s is a directory in %s added as %s instead",
1090                        ren2_dst, branch1, dst_name2);
1091                 remove_file(0, ren2_dst, 0);
1092         }
1093         if (index_only) {
1094                 remove_file_from_cache(dst_name1);
1095                 remove_file_from_cache(dst_name2);
1096                 /*
1097                  * Uncomment to leave the conflicting names in the resulting tree
1098                  *
1099                  * update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
1100                  * update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
1101                  */
1102         } else {
1103                 update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
1104                 update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
1105         }
1106         while (delp--)
1107                 free(del[delp]);
1108 }
1109
1110 static void conflict_rename_dir(struct rename *ren1,
1111                                 const char *branch1)
1112 {
1113         char *new_path = unique_path(ren1->pair->two->path, branch1);
1114         output(1, "Renamed %s to %s instead", ren1->pair->one->path, new_path);
1115         remove_file(0, ren1->pair->two->path, 0);
1116         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
1117         free(new_path);
1118 }
1119
1120 static void conflict_rename_rename_2(struct rename *ren1,
1121                                      const char *branch1,
1122                                      struct rename *ren2,
1123                                      const char *branch2)
1124 {
1125         char *new_path1 = unique_path(ren1->pair->two->path, branch1);
1126         char *new_path2 = unique_path(ren2->pair->two->path, branch2);
1127         output(1, "Renamed %s to %s and %s to %s instead",
1128                ren1->pair->one->path, new_path1,
1129                ren2->pair->one->path, new_path2);
1130         remove_file(0, ren1->pair->two->path, 0);
1131         update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
1132         update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
1133         free(new_path2);
1134         free(new_path1);
1135 }
1136
1137 static int process_renames(struct path_list *a_renames,
1138                            struct path_list *b_renames,
1139                            const char *a_branch,
1140                            const char *b_branch)
1141 {
1142         int clean_merge = 1, i, j;
1143         struct path_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
1144         const struct rename *sre;
1145
1146         for (i = 0; i < a_renames->nr; i++) {
1147                 sre = a_renames->items[i].util;
1148                 path_list_insert(sre->pair->two->path, &a_by_dst)->util
1149                         = sre->dst_entry;
1150         }
1151         for (i = 0; i < b_renames->nr; i++) {
1152                 sre = b_renames->items[i].util;
1153                 path_list_insert(sre->pair->two->path, &b_by_dst)->util
1154                         = sre->dst_entry;
1155         }
1156
1157         for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
1158                 int compare;
1159                 char *src;
1160                 struct path_list *renames1, *renames2, *renames2Dst;
1161                 struct rename *ren1 = NULL, *ren2 = NULL;
1162                 const char *branch1, *branch2;
1163                 const char *ren1_src, *ren1_dst;
1164
1165                 if (i >= a_renames->nr) {
1166                         compare = 1;
1167                         ren2 = b_renames->items[j++].util;
1168                 } else if (j >= b_renames->nr) {
1169                         compare = -1;
1170                         ren1 = a_renames->items[i++].util;
1171                 } else {
1172                         compare = strcmp(a_renames->items[i].path,
1173                                         b_renames->items[j].path);
1174                         if (compare <= 0)
1175                                 ren1 = a_renames->items[i++].util;
1176                         if (compare >= 0)
1177                                 ren2 = b_renames->items[j++].util;
1178                 }
1179
1180                 /* TODO: refactor, so that 1/2 are not needed */
1181                 if (ren1) {
1182                         renames1 = a_renames;
1183                         renames2 = b_renames;
1184                         renames2Dst = &b_by_dst;
1185                         branch1 = a_branch;
1186                         branch2 = b_branch;
1187                 } else {
1188                         struct rename *tmp;
1189                         renames1 = b_renames;
1190                         renames2 = a_renames;
1191                         renames2Dst = &a_by_dst;
1192                         branch1 = b_branch;
1193                         branch2 = a_branch;
1194                         tmp = ren2;
1195                         ren2 = ren1;
1196                         ren1 = tmp;
1197                 }
1198                 src = ren1->pair->one->path;
1199
1200                 ren1->dst_entry->processed = 1;
1201                 ren1->src_entry->processed = 1;
1202
1203                 if (ren1->processed)
1204                         continue;
1205                 ren1->processed = 1;
1206
1207                 ren1_src = ren1->pair->one->path;
1208                 ren1_dst = ren1->pair->two->path;
1209
1210                 if (ren2) {
1211                         const char *ren2_src = ren2->pair->one->path;
1212                         const char *ren2_dst = ren2->pair->two->path;
1213                         /* Renamed in 1 and renamed in 2 */
1214                         if (strcmp(ren1_src, ren2_src) != 0)
1215                                 die("ren1.src != ren2.src");
1216                         ren2->dst_entry->processed = 1;
1217                         ren2->processed = 1;
1218                         if (strcmp(ren1_dst, ren2_dst) != 0) {
1219                                 clean_merge = 0;
1220                                 output(1, "CONFLICT (rename/rename): "
1221                                        "Rename \"%s\"->\"%s\" in branch \"%s\" "
1222                                        "rename \"%s\"->\"%s\" in \"%s\"%s",
1223                                        src, ren1_dst, branch1,
1224                                        src, ren2_dst, branch2,
1225                                        index_only ? " (left unresolved)": "");
1226                                 if (index_only) {
1227                                         remove_file_from_cache(src);
1228                                         update_file(0, ren1->pair->one->sha1,
1229                                                     ren1->pair->one->mode, src);
1230                                 }
1231                                 conflict_rename_rename(ren1, branch1, ren2, branch2);
1232                         } else {
1233                                 struct merge_file_info mfi;
1234                                 remove_file(1, ren1_src, 1);
1235                                 mfi = merge_file(ren1->pair->one,
1236                                                  ren1->pair->two,
1237                                                  ren2->pair->two,
1238                                                  branch1,
1239                                                  branch2);
1240                                 if (mfi.merge || !mfi.clean)
1241                                         output(1, "Renamed %s->%s", src, ren1_dst);
1242
1243                                 if (mfi.merge)
1244                                         output(2, "Auto-merged %s", ren1_dst);
1245
1246                                 if (!mfi.clean) {
1247                                         output(1, "CONFLICT (content): merge conflict in %s",
1248                                                ren1_dst);
1249                                         clean_merge = 0;
1250
1251                                         if (!index_only)
1252                                                 update_stages(ren1_dst,
1253                                                               ren1->pair->one,
1254                                                               ren1->pair->two,
1255                                                               ren2->pair->two,
1256                                                               1 /* clear */);
1257                                 }
1258                                 update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1259                         }
1260                 } else {
1261                         /* Renamed in 1, maybe changed in 2 */
1262                         struct path_list_item *item;
1263                         /* we only use sha1 and mode of these */
1264                         struct diff_filespec src_other, dst_other;
1265                         int try_merge, stage = a_renames == renames1 ? 3: 2;
1266
1267                         remove_file(1, ren1_src, index_only || stage == 3);
1268
1269                         hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
1270                         src_other.mode = ren1->src_entry->stages[stage].mode;
1271                         hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
1272                         dst_other.mode = ren1->dst_entry->stages[stage].mode;
1273
1274                         try_merge = 0;
1275
1276                         if (path_list_has_path(&current_directory_set, ren1_dst)) {
1277                                 clean_merge = 0;
1278                                 output(1, "CONFLICT (rename/directory): Renamed %s->%s in %s "
1279                                        " directory %s added in %s",
1280                                        ren1_src, ren1_dst, branch1,
1281                                        ren1_dst, branch2);
1282                                 conflict_rename_dir(ren1, branch1);
1283                         } else if (sha_eq(src_other.sha1, null_sha1)) {
1284                                 clean_merge = 0;
1285                                 output(1, "CONFLICT (rename/delete): Renamed %s->%s in %s "
1286                                        "and deleted in %s",
1287                                        ren1_src, ren1_dst, branch1,
1288                                        branch2);
1289                                 update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
1290                         } else if (!sha_eq(dst_other.sha1, null_sha1)) {
1291                                 const char *new_path;
1292                                 clean_merge = 0;
1293                                 try_merge = 1;
1294                                 output(1, "CONFLICT (rename/add): Renamed %s->%s in %s. "
1295                                        "%s added in %s",
1296                                        ren1_src, ren1_dst, branch1,
1297                                        ren1_dst, branch2);
1298                                 new_path = unique_path(ren1_dst, branch2);
1299                                 output(1, "Added as %s instead", new_path);
1300                                 update_file(0, dst_other.sha1, dst_other.mode, new_path);
1301                         } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
1302                                 ren2 = item->util;
1303                                 clean_merge = 0;
1304                                 ren2->processed = 1;
1305                                 output(1, "CONFLICT (rename/rename): Renamed %s->%s in %s. "
1306                                        "Renamed %s->%s in %s",
1307                                        ren1_src, ren1_dst, branch1,
1308                                        ren2->pair->one->path, ren2->pair->two->path, branch2);
1309                                 conflict_rename_rename_2(ren1, branch1, ren2, branch2);
1310                         } else
1311                                 try_merge = 1;
1312
1313                         if (try_merge) {
1314                                 struct diff_filespec *o, *a, *b;
1315                                 struct merge_file_info mfi;
1316                                 src_other.path = (char *)ren1_src;
1317
1318                                 o = ren1->pair->one;
1319                                 if (a_renames == renames1) {
1320                                         a = ren1->pair->two;
1321                                         b = &src_other;
1322                                 } else {
1323                                         b = ren1->pair->two;
1324                                         a = &src_other;
1325                                 }
1326                                 mfi = merge_file(o, a, b,
1327                                                 a_branch, b_branch);
1328
1329                                 if (mfi.clean &&
1330                                     sha_eq(mfi.sha, ren1->pair->two->sha1) &&
1331                                     mfi.mode == ren1->pair->two->mode)
1332                                         /*
1333                                          * This messaged is part of
1334                                          * t6022 test. If you change
1335                                          * it update the test too.
1336                                          */
1337                                         output(3, "Skipped %s (merged same as existing)", ren1_dst);
1338                                 else {
1339                                         if (mfi.merge || !mfi.clean)
1340                                                 output(1, "Renamed %s => %s", ren1_src, ren1_dst);
1341                                         if (mfi.merge)
1342                                                 output(2, "Auto-merged %s", ren1_dst);
1343                                         if (!mfi.clean) {
1344                                                 output(1, "CONFLICT (rename/modify): Merge conflict in %s",
1345                                                        ren1_dst);
1346                                                 clean_merge = 0;
1347
1348                                                 if (!index_only)
1349                                                         update_stages(ren1_dst,
1350                                                                       o, a, b, 1);
1351                                         }
1352                                         update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1353                                 }
1354                         }
1355                 }
1356         }
1357         path_list_clear(&a_by_dst, 0);
1358         path_list_clear(&b_by_dst, 0);
1359
1360         return clean_merge;
1361 }
1362
1363 static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1364 {
1365         return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1366 }
1367
1368 /* Per entry merge function */
1369 static int process_entry(const char *path, struct stage_data *entry,
1370                          const char *branch1,
1371                          const char *branch2)
1372 {
1373         /*
1374         printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1375         print_index_entry("\tpath: ", entry);
1376         */
1377         int clean_merge = 1;
1378         unsigned o_mode = entry->stages[1].mode;
1379         unsigned a_mode = entry->stages[2].mode;
1380         unsigned b_mode = entry->stages[3].mode;
1381         unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1382         unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1383         unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1384
1385         if (o_sha && (!a_sha || !b_sha)) {
1386                 /* Case A: Deleted in one */
1387                 if ((!a_sha && !b_sha) ||
1388                     (sha_eq(a_sha, o_sha) && !b_sha) ||
1389                     (!a_sha && sha_eq(b_sha, o_sha))) {
1390                         /* Deleted in both or deleted in one and
1391                          * unchanged in the other */
1392                         if (a_sha)
1393                                 output(2, "Removed %s", path);
1394                         /* do not touch working file if it did not exist */
1395                         remove_file(1, path, !a_sha);
1396                 } else {
1397                         /* Deleted in one and changed in the other */
1398                         clean_merge = 0;
1399                         if (!a_sha) {
1400                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1401                                        "and modified in %s. Version %s of %s left in tree.",
1402                                        path, branch1,
1403                                        branch2, branch2, path);
1404                                 update_file(0, b_sha, b_mode, path);
1405                         } else {
1406                                 output(1, "CONFLICT (delete/modify): %s deleted in %s "
1407                                        "and modified in %s. Version %s of %s left in tree.",
1408                                        path, branch2,
1409                                        branch1, branch1, path);
1410                                 update_file(0, a_sha, a_mode, path);
1411                         }
1412                 }
1413
1414         } else if ((!o_sha && a_sha && !b_sha) ||
1415                    (!o_sha && !a_sha && b_sha)) {
1416                 /* Case B: Added in one. */
1417                 const char *add_branch;
1418                 const char *other_branch;
1419                 unsigned mode;
1420                 const unsigned char *sha;
1421                 const char *conf;
1422
1423                 if (a_sha) {
1424                         add_branch = branch1;
1425                         other_branch = branch2;
1426                         mode = a_mode;
1427                         sha = a_sha;
1428                         conf = "file/directory";
1429                 } else {
1430                         add_branch = branch2;
1431                         other_branch = branch1;
1432                         mode = b_mode;
1433                         sha = b_sha;
1434                         conf = "directory/file";
1435                 }
1436                 if (path_list_has_path(&current_directory_set, path)) {
1437                         const char *new_path = unique_path(path, add_branch);
1438                         clean_merge = 0;
1439                         output(1, "CONFLICT (%s): There is a directory with name %s in %s. "
1440                                "Added %s as %s",
1441                                conf, path, other_branch, path, new_path);
1442                         remove_file(0, path, 0);
1443                         update_file(0, sha, mode, new_path);
1444                 } else {
1445                         output(2, "Added %s", path);
1446                         update_file(1, sha, mode, path);
1447                 }
1448         } else if (a_sha && b_sha) {
1449                 /* Case C: Added in both (check for same permissions) and */
1450                 /* case D: Modified in both, but differently. */
1451                 const char *reason = "content";
1452                 struct merge_file_info mfi;
1453                 struct diff_filespec o, a, b;
1454
1455                 if (!o_sha) {
1456                         reason = "add/add";
1457                         o_sha = (unsigned char *)null_sha1;
1458                 }
1459                 output(2, "Auto-merged %s", path);
1460                 o.path = a.path = b.path = (char *)path;
1461                 hashcpy(o.sha1, o_sha);
1462                 o.mode = o_mode;
1463                 hashcpy(a.sha1, a_sha);
1464                 a.mode = a_mode;
1465                 hashcpy(b.sha1, b_sha);
1466                 b.mode = b_mode;
1467
1468                 mfi = merge_file(&o, &a, &b,
1469                                  branch1, branch2);
1470
1471                 clean_merge = mfi.clean;
1472                 if (mfi.clean)
1473                         update_file(1, mfi.sha, mfi.mode, path);
1474                 else if (S_ISGITLINK(mfi.mode))
1475                         output(1, "CONFLICT (submodule): Merge conflict in %s "
1476                                "- needs %s", path, sha1_to_hex(b.sha1));
1477                 else {
1478                         output(1, "CONFLICT (%s): Merge conflict in %s",
1479                                         reason, path);
1480
1481                         if (index_only)
1482                                 update_file(0, mfi.sha, mfi.mode, path);
1483                         else
1484                                 update_file_flags(mfi.sha, mfi.mode, path,
1485                                               0 /* update_cache */, 1 /* update_working_directory */);
1486                 }
1487         } else if (!o_sha && !a_sha && !b_sha) {
1488                 /*
1489                  * this entry was deleted altogether. a_mode == 0 means
1490                  * we had that path and want to actively remove it.
1491                  */
1492                 remove_file(1, path, !a_mode);
1493         } else
1494                 die("Fatal merge failure, shouldn't happen.");
1495
1496         return clean_merge;
1497 }
1498
1499 static int merge_trees(struct tree *head,
1500                        struct tree *merge,
1501                        struct tree *common,
1502                        const char *branch1,
1503                        const char *branch2,
1504                        struct tree **result)
1505 {
1506         int code, clean;
1507
1508         if (subtree_merge) {
1509                 merge = shift_tree_object(head, merge);
1510                 common = shift_tree_object(head, common);
1511         }
1512
1513         if (sha_eq(common->object.sha1, merge->object.sha1)) {
1514                 output(0, "Already uptodate!");
1515                 *result = head;
1516                 return 1;
1517         }
1518
1519         code = git_merge_trees(index_only, common, head, merge);
1520
1521         if (code != 0)
1522                 die("merging of trees %s and %s failed",
1523                     sha1_to_hex(head->object.sha1),
1524                     sha1_to_hex(merge->object.sha1));
1525
1526         if (unmerged_index()) {
1527                 struct path_list *entries, *re_head, *re_merge;
1528                 int i;
1529                 path_list_clear(&current_file_set, 1);
1530                 path_list_clear(&current_directory_set, 1);
1531                 get_files_dirs(head);
1532                 get_files_dirs(merge);
1533
1534                 entries = get_unmerged();
1535                 re_head  = get_renames(head, common, head, merge, entries);
1536                 re_merge = get_renames(merge, common, head, merge, entries);
1537                 clean = process_renames(re_head, re_merge,
1538                                 branch1, branch2);
1539                 for (i = 0; i < entries->nr; i++) {
1540                         const char *path = entries->items[i].path;
1541                         struct stage_data *e = entries->items[i].util;
1542                         if (!e->processed
1543                                 && !process_entry(path, e, branch1, branch2))
1544                                 clean = 0;
1545                 }
1546
1547                 path_list_clear(re_merge, 0);
1548                 path_list_clear(re_head, 0);
1549                 path_list_clear(entries, 1);
1550
1551         }
1552         else
1553                 clean = 1;
1554
1555         if (index_only)
1556                 *result = git_write_tree();
1557
1558         return clean;
1559 }
1560
1561 static struct commit_list *reverse_commit_list(struct commit_list *list)
1562 {
1563         struct commit_list *next = NULL, *current, *backup;
1564         for (current = list; current; current = backup) {
1565                 backup = current->next;
1566                 current->next = next;
1567                 next = current;
1568         }
1569         return next;
1570 }
1571
1572 /*
1573  * Merge the commits h1 and h2, return the resulting virtual
1574  * commit object and a flag indicating the cleanness of the merge.
1575  */
1576 static int merge(struct commit *h1,
1577                  struct commit *h2,
1578                  const char *branch1,
1579                  const char *branch2,
1580                  struct commit_list *ca,
1581                  struct commit **result)
1582 {
1583         struct commit_list *iter;
1584         struct commit *merged_common_ancestors;
1585         struct tree *mrtree = mrtree;
1586         int clean;
1587
1588         if (show(4)) {
1589                 output(4, "Merging:");
1590                 output_commit_title(h1);
1591                 output_commit_title(h2);
1592         }
1593
1594         if (!ca) {
1595                 ca = get_merge_bases(h1, h2, 1);
1596                 ca = reverse_commit_list(ca);
1597         }
1598
1599         if (show(5)) {
1600                 output(5, "found %u common ancestor(s):", commit_list_count(ca));
1601                 for (iter = ca; iter; iter = iter->next)
1602                         output_commit_title(iter->item);
1603         }
1604
1605         merged_common_ancestors = pop_commit(&ca);
1606         if (merged_common_ancestors == NULL) {
1607                 /* if there is no common ancestor, make an empty tree */
1608                 struct tree *tree = xcalloc(1, sizeof(struct tree));
1609
1610                 tree->object.parsed = 1;
1611                 tree->object.type = OBJ_TREE;
1612                 pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1613                 merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1614         }
1615
1616         for (iter = ca; iter; iter = iter->next) {
1617                 call_depth++;
1618                 /*
1619                  * When the merge fails, the result contains files
1620                  * with conflict markers. The cleanness flag is
1621                  * ignored, it was never actually used, as result of
1622                  * merge_trees has always overwritten it: the committed
1623                  * "conflicts" were already resolved.
1624                  */
1625                 discard_cache();
1626                 merge(merged_common_ancestors, iter->item,
1627                       "Temporary merge branch 1",
1628                       "Temporary merge branch 2",
1629                       NULL,
1630                       &merged_common_ancestors);
1631                 call_depth--;
1632
1633                 if (!merged_common_ancestors)
1634                         die("merge returned no commit");
1635         }
1636
1637         discard_cache();
1638         if (!call_depth) {
1639                 read_cache();
1640                 index_only = 0;
1641         } else
1642                 index_only = 1;
1643
1644         clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
1645                             branch1, branch2, &mrtree);
1646
1647         if (index_only) {
1648                 *result = make_virtual_commit(mrtree, "merged tree");
1649                 commit_list_insert(h1, &(*result)->parents);
1650                 commit_list_insert(h2, &(*result)->parents->next);
1651         }
1652         flush_output();
1653         return clean;
1654 }
1655
1656 static const char *better_branch_name(const char *branch)
1657 {
1658         static char githead_env[8 + 40 + 1];
1659         char *name;
1660
1661         if (strlen(branch) != 40)
1662                 return branch;
1663         sprintf(githead_env, "GITHEAD_%s", branch);
1664         name = getenv(githead_env);
1665         return name ? name : branch;
1666 }
1667
1668 static struct commit *get_ref(const char *ref)
1669 {
1670         unsigned char sha1[20];
1671         struct object *object;
1672
1673         if (get_sha1(ref, sha1))
1674                 die("Could not resolve ref '%s'", ref);
1675         object = deref_tag(parse_object(sha1), ref, strlen(ref));
1676         if (object->type == OBJ_TREE)
1677                 return make_virtual_commit((struct tree*)object,
1678                         better_branch_name(ref));
1679         if (object->type != OBJ_COMMIT)
1680                 return NULL;
1681         if (parse_commit((struct commit *)object))
1682                 die("Could not parse commit '%s'", sha1_to_hex(object->sha1));
1683         return (struct commit *)object;
1684 }
1685
1686 static int merge_config(const char *var, const char *value)
1687 {
1688         if (!strcasecmp(var, "merge.verbosity")) {
1689                 verbosity = git_config_int(var, value);
1690                 return 0;
1691         }
1692         if (!strcasecmp(var, "diff.renamelimit")) {
1693                 rename_limit = git_config_int(var, value);
1694                 return 0;
1695         }
1696         return git_default_config(var, value);
1697 }
1698
1699 int main(int argc, char *argv[])
1700 {
1701         static const char *bases[20];
1702         static unsigned bases_count = 0;
1703         int i, clean;
1704         const char *branch1, *branch2;
1705         struct commit *result, *h1, *h2;
1706         struct commit_list *ca = NULL;
1707         struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1708         int index_fd;
1709
1710         if (argv[0]) {
1711                 int namelen = strlen(argv[0]);
1712                 if (8 < namelen &&
1713                     !strcmp(argv[0] + namelen - 8, "-subtree"))
1714                         subtree_merge = 1;
1715         }
1716
1717         git_config(merge_config);
1718         if (getenv("GIT_MERGE_VERBOSITY"))
1719                 verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1720
1721         if (argc < 4)
1722                 die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
1723
1724         for (i = 1; i < argc; ++i) {
1725                 if (!strcmp(argv[i], "--"))
1726                         break;
1727                 if (bases_count < sizeof(bases)/sizeof(*bases))
1728                         bases[bases_count++] = argv[i];
1729         }
1730         if (argc - i != 3) /* "--" "<head>" "<remote>" */
1731                 die("Not handling anything other than two heads merge.");
1732         if (verbosity >= 5)
1733                 buffer_output = 0;
1734
1735         branch1 = argv[++i];
1736         branch2 = argv[++i];
1737
1738         h1 = get_ref(branch1);
1739         h2 = get_ref(branch2);
1740
1741         branch1 = better_branch_name(branch1);
1742         branch2 = better_branch_name(branch2);
1743
1744         if (show(3))
1745                 printf("Merging %s with %s\n", branch1, branch2);
1746
1747         index_fd = hold_locked_index(lock, 1);
1748
1749         for (i = 0; i < bases_count; i++) {
1750                 struct commit *ancestor = get_ref(bases[i]);
1751                 ca = commit_list_insert(ancestor, &ca);
1752         }
1753         clean = merge(h1, h2, branch1, branch2, ca, &result);
1754
1755         if (active_cache_changed &&
1756             (write_cache(index_fd, active_cache, active_nr) ||
1757              commit_locked_index(lock)))
1758                         die ("unable to write %s", get_index_file());
1759
1760         return clean ? 0: 1;
1761 }