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