merge-recursive.con commit Merge branch 'maint' (ada59fc)
   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
  21static int subtree_merge;
  22
  23static 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
  43static 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
  51static 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 */
  67static 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 */
  78struct stage_data
  79{
  80        struct
  81        {
  82                unsigned mode;
  83                unsigned char sha[20];
  84        } stages[4];
  85        unsigned processed:1;
  86};
  87
  88static struct path_list current_file_set = {NULL, 0, 0, 1};
  89static struct path_list current_directory_set = {NULL, 0, 0, 1};
  90
  91static int call_depth = 0;
  92static int verbosity = 2;
  93static int rename_limit = -1;
  94static int buffer_output = 1;
  95static struct strbuf obuf = STRBUF_INIT;
  96
  97static int show(int v)
  98{
  99        return (!call_depth && verbosity >= v) || verbosity >= 5;
 100}
 101
 102static void flush_output(void)
 103{
 104        if (obuf.len) {
 105                fputs(obuf.buf, stdout);
 106                strbuf_reset(&obuf);
 107        }
 108}
 109
 110static 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
 143static 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
 170static 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 */
 189static int index_only = 0;
 190
 191static 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
 197static 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
 224static 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
 235static 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
 263static 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
 282static 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 a index_entry instance which doesn't have to correspond to
 293 * a real cache entry in Git's index.
 294 */
 295static 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 */
 316static 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
 343struct 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 */
 357static 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
 410static 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
 430static 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
 448static 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
 466static 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
 487static 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
 496static 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
 513static 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
 538static 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                buf = read_sha1_file(sha, &type, &size);
 553                if (!buf)
 554                        die("cannot read object %s '%s'", sha1_to_hex(sha), path);
 555                if (type != OBJ_BLOB)
 556                        die("blob expected for %s '%s'", sha1_to_hex(sha), path);
 557
 558                if (make_room_for_path(path) < 0) {
 559                        update_wd = 0;
 560                        goto update_index;
 561                }
 562                if (S_ISREG(mode) || (!has_symlinks && S_ISLNK(mode))) {
 563                        int fd;
 564                        if (mode & 0100)
 565                                mode = 0777;
 566                        else
 567                                mode = 0666;
 568                        fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
 569                        if (fd < 0)
 570                                die("failed to open %s: %s", path, strerror(errno));
 571                        flush_buffer(fd, buf, size);
 572                        close(fd);
 573                } else if (S_ISLNK(mode)) {
 574                        char *lnk = xmemdupz(buf, size);
 575                        mkdir_p(path, 0777);
 576                        unlink(path);
 577                        symlink(lnk, path);
 578                        free(lnk);
 579                } else
 580                        die("do not know what to do with %06o %s '%s'",
 581                            mode, sha1_to_hex(sha), path);
 582        }
 583 update_index:
 584        if (update_cache)
 585                add_cacheinfo(mode, sha, path, 0, update_wd, ADD_CACHE_OK_TO_ADD);
 586}
 587
 588static void update_file(int clean,
 589                        const unsigned char *sha,
 590                        unsigned mode,
 591                        const char *path)
 592{
 593        update_file_flags(sha, mode, path, index_only || clean, !index_only);
 594}
 595
 596/* Low level file merging, update and removal */
 597
 598struct merge_file_info
 599{
 600        unsigned char sha[20];
 601        unsigned mode;
 602        unsigned clean:1,
 603                 merge:1;
 604};
 605
 606static void fill_mm(const unsigned char *sha1, mmfile_t *mm)
 607{
 608        unsigned long size;
 609        enum object_type type;
 610
 611        if (!hashcmp(sha1, null_sha1)) {
 612                mm->ptr = xstrdup("");
 613                mm->size = 0;
 614                return;
 615        }
 616
 617        mm->ptr = read_sha1_file(sha1, &type, &size);
 618        if (!mm->ptr || type != OBJ_BLOB)
 619                die("unable to read blob object %s", sha1_to_hex(sha1));
 620        mm->size = size;
 621}
 622
 623/*
 624 * Customizable low-level merge drivers support.
 625 */
 626
 627struct ll_merge_driver;
 628typedef int (*ll_merge_fn)(const struct ll_merge_driver *,
 629                           const char *path,
 630                           mmfile_t *orig,
 631                           mmfile_t *src1, const char *name1,
 632                           mmfile_t *src2, const char *name2,
 633                           mmbuffer_t *result);
 634
 635struct ll_merge_driver {
 636        const char *name;
 637        const char *description;
 638        ll_merge_fn fn;
 639        const char *recursive;
 640        struct ll_merge_driver *next;
 641        char *cmdline;
 642};
 643
 644/*
 645 * Built-in low-levels
 646 */
 647static int ll_binary_merge(const struct ll_merge_driver *drv_unused,
 648                           const char *path_unused,
 649                           mmfile_t *orig,
 650                           mmfile_t *src1, const char *name1,
 651                           mmfile_t *src2, const char *name2,
 652                           mmbuffer_t *result)
 653{
 654        /*
 655         * The tentative merge result is "ours" for the final round,
 656         * or common ancestor for an internal merge.  Still return
 657         * "conflicted merge" status.
 658         */
 659        mmfile_t *stolen = index_only ? orig : src1;
 660
 661        result->ptr = stolen->ptr;
 662        result->size = stolen->size;
 663        stolen->ptr = NULL;
 664        return 1;
 665}
 666
 667static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
 668                        const char *path_unused,
 669                        mmfile_t *orig,
 670                        mmfile_t *src1, const char *name1,
 671                        mmfile_t *src2, const char *name2,
 672                        mmbuffer_t *result)
 673{
 674        xpparam_t xpp;
 675
 676        if (buffer_is_binary(orig->ptr, orig->size) ||
 677            buffer_is_binary(src1->ptr, src1->size) ||
 678            buffer_is_binary(src2->ptr, src2->size)) {
 679                warning("Cannot merge binary files: %s vs. %s\n",
 680                        name1, name2);
 681                return ll_binary_merge(drv_unused, path_unused,
 682                                       orig, src1, name1,
 683                                       src2, name2,
 684                                       result);
 685        }
 686
 687        memset(&xpp, 0, sizeof(xpp));
 688        return xdl_merge(orig,
 689                         src1, name1,
 690                         src2, name2,
 691                         &xpp, XDL_MERGE_ZEALOUS,
 692                         result);
 693}
 694
 695static int ll_union_merge(const struct ll_merge_driver *drv_unused,
 696                          const char *path_unused,
 697                          mmfile_t *orig,
 698                          mmfile_t *src1, const char *name1,
 699                          mmfile_t *src2, const char *name2,
 700                          mmbuffer_t *result)
 701{
 702        char *src, *dst;
 703        long size;
 704        const int marker_size = 7;
 705
 706        int status = ll_xdl_merge(drv_unused, path_unused,
 707                                  orig, src1, NULL, src2, NULL, result);
 708        if (status <= 0)
 709                return status;
 710        size = result->size;
 711        src = dst = result->ptr;
 712        while (size) {
 713                char ch;
 714                if ((marker_size < size) &&
 715                    (*src == '<' || *src == '=' || *src == '>')) {
 716                        int i;
 717                        ch = *src;
 718                        for (i = 0; i < marker_size; i++)
 719                                if (src[i] != ch)
 720                                        goto not_a_marker;
 721                        if (src[marker_size] != '\n')
 722                                goto not_a_marker;
 723                        src += marker_size + 1;
 724                        size -= marker_size + 1;
 725                        continue;
 726                }
 727        not_a_marker:
 728                do {
 729                        ch = *src++;
 730                        *dst++ = ch;
 731                        size--;
 732                } while (ch != '\n' && size);
 733        }
 734        result->size = dst - result->ptr;
 735        return 0;
 736}
 737
 738#define LL_BINARY_MERGE 0
 739#define LL_TEXT_MERGE 1
 740#define LL_UNION_MERGE 2
 741static struct ll_merge_driver ll_merge_drv[] = {
 742        { "binary", "built-in binary merge", ll_binary_merge },
 743        { "text", "built-in 3-way text merge", ll_xdl_merge },
 744        { "union", "built-in union merge", ll_union_merge },
 745};
 746
 747static void create_temp(mmfile_t *src, char *path)
 748{
 749        int fd;
 750
 751        strcpy(path, ".merge_file_XXXXXX");
 752        fd = xmkstemp(path);
 753        if (write_in_full(fd, src->ptr, src->size) != src->size)
 754                die("unable to write temp-file");
 755        close(fd);
 756}
 757
 758/*
 759 * User defined low-level merge driver support.
 760 */
 761static int ll_ext_merge(const struct ll_merge_driver *fn,
 762                        const char *path,
 763                        mmfile_t *orig,
 764                        mmfile_t *src1, const char *name1,
 765                        mmfile_t *src2, const char *name2,
 766                        mmbuffer_t *result)
 767{
 768        char temp[3][50];
 769        char cmdbuf[2048];
 770        struct interp table[] = {
 771                { "%O" },
 772                { "%A" },
 773                { "%B" },
 774        };
 775        struct child_process child;
 776        const char *args[20];
 777        int status, fd, i;
 778        struct stat st;
 779
 780        if (fn->cmdline == NULL)
 781                die("custom merge driver %s lacks command line.", fn->name);
 782
 783        result->ptr = NULL;
 784        result->size = 0;
 785        create_temp(orig, temp[0]);
 786        create_temp(src1, temp[1]);
 787        create_temp(src2, temp[2]);
 788
 789        interp_set_entry(table, 0, temp[0]);
 790        interp_set_entry(table, 1, temp[1]);
 791        interp_set_entry(table, 2, temp[2]);
 792
 793        output(1, "merging %s using %s", path,
 794               fn->description ? fn->description : fn->name);
 795
 796        interpolate(cmdbuf, sizeof(cmdbuf), fn->cmdline, table, 3);
 797
 798        memset(&child, 0, sizeof(child));
 799        child.argv = args;
 800        args[0] = "sh";
 801        args[1] = "-c";
 802        args[2] = cmdbuf;
 803        args[3] = NULL;
 804
 805        status = run_command(&child);
 806        if (status < -ERR_RUN_COMMAND_FORK)
 807                ; /* failure in run-command */
 808        else
 809                status = -status;
 810        fd = open(temp[1], O_RDONLY);
 811        if (fd < 0)
 812                goto bad;
 813        if (fstat(fd, &st))
 814                goto close_bad;
 815        result->size = st.st_size;
 816        result->ptr = xmalloc(result->size + 1);
 817        if (read_in_full(fd, result->ptr, result->size) != result->size) {
 818                free(result->ptr);
 819                result->ptr = NULL;
 820                result->size = 0;
 821        }
 822 close_bad:
 823        close(fd);
 824 bad:
 825        for (i = 0; i < 3; i++)
 826                unlink(temp[i]);
 827        return status;
 828}
 829
 830/*
 831 * merge.default and merge.driver configuration items
 832 */
 833static struct ll_merge_driver *ll_user_merge, **ll_user_merge_tail;
 834static const char *default_ll_merge;
 835
 836static int read_merge_config(const char *var, const char *value)
 837{
 838        struct ll_merge_driver *fn;
 839        const char *ep, *name;
 840        int namelen;
 841
 842        if (!strcmp(var, "merge.default")) {
 843                if (value)
 844                        default_ll_merge = strdup(value);
 845                return 0;
 846        }
 847
 848        /*
 849         * We are not interested in anything but "merge.<name>.variable";
 850         * especially, we do not want to look at variables such as
 851         * "merge.summary", "merge.tool", and "merge.verbosity".
 852         */
 853        if (prefixcmp(var, "merge.") || (ep = strrchr(var, '.')) == var + 5)
 854                return 0;
 855
 856        /*
 857         * Find existing one as we might be processing merge.<name>.var2
 858         * after seeing merge.<name>.var1.
 859         */
 860        name = var + 6;
 861        namelen = ep - name;
 862        for (fn = ll_user_merge; fn; fn = fn->next)
 863                if (!strncmp(fn->name, name, namelen) && !fn->name[namelen])
 864                        break;
 865        if (!fn) {
 866                fn = xcalloc(1, sizeof(struct ll_merge_driver));
 867                fn->name = xmemdupz(name, namelen);
 868                fn->fn = ll_ext_merge;
 869                *ll_user_merge_tail = fn;
 870                ll_user_merge_tail = &(fn->next);
 871        }
 872
 873        ep++;
 874
 875        if (!strcmp("name", ep)) {
 876                if (!value)
 877                        return error("%s: lacks value", var);
 878                fn->description = strdup(value);
 879                return 0;
 880        }
 881
 882        if (!strcmp("driver", ep)) {
 883                if (!value)
 884                        return error("%s: lacks value", var);
 885                /*
 886                 * merge.<name>.driver specifies the command line:
 887                 *
 888                 *      command-line
 889                 *
 890                 * The command-line will be interpolated with the following
 891                 * tokens and is given to the shell:
 892                 *
 893                 *    %O - temporary file name for the merge base.
 894                 *    %A - temporary file name for our version.
 895                 *    %B - temporary file name for the other branches' version.
 896                 *
 897                 * The external merge driver should write the results in the
 898                 * file named by %A, and signal that it has done with zero exit
 899                 * status.
 900                 */
 901                fn->cmdline = strdup(value);
 902                return 0;
 903        }
 904
 905        if (!strcmp("recursive", ep)) {
 906                if (!value)
 907                        return error("%s: lacks value", var);
 908                fn->recursive = strdup(value);
 909                return 0;
 910        }
 911
 912        return 0;
 913}
 914
 915static void initialize_ll_merge(void)
 916{
 917        if (ll_user_merge_tail)
 918                return;
 919        ll_user_merge_tail = &ll_user_merge;
 920        git_config(read_merge_config);
 921}
 922
 923static const struct ll_merge_driver *find_ll_merge_driver(const char *merge_attr)
 924{
 925        struct ll_merge_driver *fn;
 926        const char *name;
 927        int i;
 928
 929        initialize_ll_merge();
 930
 931        if (ATTR_TRUE(merge_attr))
 932                return &ll_merge_drv[LL_TEXT_MERGE];
 933        else if (ATTR_FALSE(merge_attr))
 934                return &ll_merge_drv[LL_BINARY_MERGE];
 935        else if (ATTR_UNSET(merge_attr)) {
 936                if (!default_ll_merge)
 937                        return &ll_merge_drv[LL_TEXT_MERGE];
 938                else
 939                        name = default_ll_merge;
 940        }
 941        else
 942                name = merge_attr;
 943
 944        for (fn = ll_user_merge; fn; fn = fn->next)
 945                if (!strcmp(fn->name, name))
 946                        return fn;
 947
 948        for (i = 0; i < ARRAY_SIZE(ll_merge_drv); i++)
 949                if (!strcmp(ll_merge_drv[i].name, name))
 950                        return &ll_merge_drv[i];
 951
 952        /* default to the 3-way */
 953        return &ll_merge_drv[LL_TEXT_MERGE];
 954}
 955
 956static const char *git_path_check_merge(const char *path)
 957{
 958        static struct git_attr_check attr_merge_check;
 959
 960        if (!attr_merge_check.attr)
 961                attr_merge_check.attr = git_attr("merge", 5);
 962
 963        if (git_checkattr(path, 1, &attr_merge_check))
 964                return NULL;
 965        return attr_merge_check.value;
 966}
 967
 968static int ll_merge(mmbuffer_t *result_buf,
 969                    struct diff_filespec *o,
 970                    struct diff_filespec *a,
 971                    struct diff_filespec *b,
 972                    const char *branch1,
 973                    const char *branch2)
 974{
 975        mmfile_t orig, src1, src2;
 976        char *name1, *name2;
 977        int merge_status;
 978        const char *ll_driver_name;
 979        const struct ll_merge_driver *driver;
 980
 981        name1 = xstrdup(mkpath("%s:%s", branch1, a->path));
 982        name2 = xstrdup(mkpath("%s:%s", branch2, b->path));
 983
 984        fill_mm(o->sha1, &orig);
 985        fill_mm(a->sha1, &src1);
 986        fill_mm(b->sha1, &src2);
 987
 988        ll_driver_name = git_path_check_merge(a->path);
 989        driver = find_ll_merge_driver(ll_driver_name);
 990
 991        if (index_only && driver->recursive)
 992                driver = find_ll_merge_driver(driver->recursive);
 993        merge_status = driver->fn(driver, a->path,
 994                                  &orig, &src1, name1, &src2, name2,
 995                                  result_buf);
 996
 997        free(name1);
 998        free(name2);
 999        free(orig.ptr);
1000        free(src1.ptr);
1001        free(src2.ptr);
1002        return merge_status;
1003}
1004
1005static struct merge_file_info merge_file(struct diff_filespec *o,
1006                struct diff_filespec *a, struct diff_filespec *b,
1007                const char *branch1, const char *branch2)
1008{
1009        struct merge_file_info result;
1010        result.merge = 0;
1011        result.clean = 1;
1012
1013        if ((S_IFMT & a->mode) != (S_IFMT & b->mode)) {
1014                result.clean = 0;
1015                if (S_ISREG(a->mode)) {
1016                        result.mode = a->mode;
1017                        hashcpy(result.sha, a->sha1);
1018                } else {
1019                        result.mode = b->mode;
1020                        hashcpy(result.sha, b->sha1);
1021                }
1022        } else {
1023                if (!sha_eq(a->sha1, o->sha1) && !sha_eq(b->sha1, o->sha1))
1024                        result.merge = 1;
1025
1026                result.mode = a->mode == o->mode ? b->mode: a->mode;
1027
1028                if (sha_eq(a->sha1, o->sha1))
1029                        hashcpy(result.sha, b->sha1);
1030                else if (sha_eq(b->sha1, o->sha1))
1031                        hashcpy(result.sha, a->sha1);
1032                else if (S_ISREG(a->mode)) {
1033                        mmbuffer_t result_buf;
1034                        int merge_status;
1035
1036                        merge_status = ll_merge(&result_buf, o, a, b,
1037                                                branch1, branch2);
1038
1039                        if ((merge_status < 0) || !result_buf.ptr)
1040                                die("Failed to execute internal merge");
1041
1042                        if (write_sha1_file(result_buf.ptr, result_buf.size,
1043                                            blob_type, result.sha))
1044                                die("Unable to add %s to database",
1045                                    a->path);
1046
1047                        free(result_buf.ptr);
1048                        result.clean = (merge_status == 0);
1049                } else {
1050                        if (!(S_ISLNK(a->mode) || S_ISLNK(b->mode)))
1051                                die("cannot merge modes?");
1052
1053                        hashcpy(result.sha, a->sha1);
1054
1055                        if (!sha_eq(a->sha1, b->sha1))
1056                                result.clean = 0;
1057                }
1058        }
1059
1060        return result;
1061}
1062
1063static void conflict_rename_rename(struct rename *ren1,
1064                                   const char *branch1,
1065                                   struct rename *ren2,
1066                                   const char *branch2)
1067{
1068        char *del[2];
1069        int delp = 0;
1070        const char *ren1_dst = ren1->pair->two->path;
1071        const char *ren2_dst = ren2->pair->two->path;
1072        const char *dst_name1 = ren1_dst;
1073        const char *dst_name2 = ren2_dst;
1074        if (path_list_has_path(&current_directory_set, ren1_dst)) {
1075                dst_name1 = del[delp++] = unique_path(ren1_dst, branch1);
1076                output(1, "%s is a directory in %s added as %s instead",
1077                       ren1_dst, branch2, dst_name1);
1078                remove_file(0, ren1_dst, 0);
1079        }
1080        if (path_list_has_path(&current_directory_set, ren2_dst)) {
1081                dst_name2 = del[delp++] = unique_path(ren2_dst, branch2);
1082                output(1, "%s is a directory in %s added as %s instead",
1083                       ren2_dst, branch1, dst_name2);
1084                remove_file(0, ren2_dst, 0);
1085        }
1086        if (index_only) {
1087                remove_file_from_cache(dst_name1);
1088                remove_file_from_cache(dst_name2);
1089                /*
1090                 * Uncomment to leave the conflicting names in the resulting tree
1091                 *
1092                 * update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, dst_name1);
1093                 * update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, dst_name2);
1094                 */
1095        } else {
1096                update_stages(dst_name1, NULL, ren1->pair->two, NULL, 1);
1097                update_stages(dst_name2, NULL, NULL, ren2->pair->two, 1);
1098        }
1099        while (delp--)
1100                free(del[delp]);
1101}
1102
1103static void conflict_rename_dir(struct rename *ren1,
1104                                const char *branch1)
1105{
1106        char *new_path = unique_path(ren1->pair->two->path, branch1);
1107        output(1, "Renamed %s to %s instead", ren1->pair->one->path, new_path);
1108        remove_file(0, ren1->pair->two->path, 0);
1109        update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path);
1110        free(new_path);
1111}
1112
1113static void conflict_rename_rename_2(struct rename *ren1,
1114                                     const char *branch1,
1115                                     struct rename *ren2,
1116                                     const char *branch2)
1117{
1118        char *new_path1 = unique_path(ren1->pair->two->path, branch1);
1119        char *new_path2 = unique_path(ren2->pair->two->path, branch2);
1120        output(1, "Renamed %s to %s and %s to %s instead",
1121               ren1->pair->one->path, new_path1,
1122               ren2->pair->one->path, new_path2);
1123        remove_file(0, ren1->pair->two->path, 0);
1124        update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, new_path1);
1125        update_file(0, ren2->pair->two->sha1, ren2->pair->two->mode, new_path2);
1126        free(new_path2);
1127        free(new_path1);
1128}
1129
1130static int process_renames(struct path_list *a_renames,
1131                           struct path_list *b_renames,
1132                           const char *a_branch,
1133                           const char *b_branch)
1134{
1135        int clean_merge = 1, i, j;
1136        struct path_list a_by_dst = {NULL, 0, 0, 0}, b_by_dst = {NULL, 0, 0, 0};
1137        const struct rename *sre;
1138
1139        for (i = 0; i < a_renames->nr; i++) {
1140                sre = a_renames->items[i].util;
1141                path_list_insert(sre->pair->two->path, &a_by_dst)->util
1142                        = sre->dst_entry;
1143        }
1144        for (i = 0; i < b_renames->nr; i++) {
1145                sre = b_renames->items[i].util;
1146                path_list_insert(sre->pair->two->path, &b_by_dst)->util
1147                        = sre->dst_entry;
1148        }
1149
1150        for (i = 0, j = 0; i < a_renames->nr || j < b_renames->nr;) {
1151                int compare;
1152                char *src;
1153                struct path_list *renames1, *renames2, *renames2Dst;
1154                struct rename *ren1 = NULL, *ren2 = NULL;
1155                const char *branch1, *branch2;
1156                const char *ren1_src, *ren1_dst;
1157
1158                if (i >= a_renames->nr) {
1159                        compare = 1;
1160                        ren2 = b_renames->items[j++].util;
1161                } else if (j >= b_renames->nr) {
1162                        compare = -1;
1163                        ren1 = a_renames->items[i++].util;
1164                } else {
1165                        compare = strcmp(a_renames->items[i].path,
1166                                        b_renames->items[j].path);
1167                        if (compare <= 0)
1168                                ren1 = a_renames->items[i++].util;
1169                        if (compare >= 0)
1170                                ren2 = b_renames->items[j++].util;
1171                }
1172
1173                /* TODO: refactor, so that 1/2 are not needed */
1174                if (ren1) {
1175                        renames1 = a_renames;
1176                        renames2 = b_renames;
1177                        renames2Dst = &b_by_dst;
1178                        branch1 = a_branch;
1179                        branch2 = b_branch;
1180                } else {
1181                        struct rename *tmp;
1182                        renames1 = b_renames;
1183                        renames2 = a_renames;
1184                        renames2Dst = &a_by_dst;
1185                        branch1 = b_branch;
1186                        branch2 = a_branch;
1187                        tmp = ren2;
1188                        ren2 = ren1;
1189                        ren1 = tmp;
1190                }
1191                src = ren1->pair->one->path;
1192
1193                ren1->dst_entry->processed = 1;
1194                ren1->src_entry->processed = 1;
1195
1196                if (ren1->processed)
1197                        continue;
1198                ren1->processed = 1;
1199
1200                ren1_src = ren1->pair->one->path;
1201                ren1_dst = ren1->pair->two->path;
1202
1203                if (ren2) {
1204                        const char *ren2_src = ren2->pair->one->path;
1205                        const char *ren2_dst = ren2->pair->two->path;
1206                        /* Renamed in 1 and renamed in 2 */
1207                        if (strcmp(ren1_src, ren2_src) != 0)
1208                                die("ren1.src != ren2.src");
1209                        ren2->dst_entry->processed = 1;
1210                        ren2->processed = 1;
1211                        if (strcmp(ren1_dst, ren2_dst) != 0) {
1212                                clean_merge = 0;
1213                                output(1, "CONFLICT (rename/rename): "
1214                                       "Rename \"%s\"->\"%s\" in branch \"%s\" "
1215                                       "rename \"%s\"->\"%s\" in \"%s\"%s",
1216                                       src, ren1_dst, branch1,
1217                                       src, ren2_dst, branch2,
1218                                       index_only ? " (left unresolved)": "");
1219                                if (index_only) {
1220                                        remove_file_from_cache(src);
1221                                        update_file(0, ren1->pair->one->sha1,
1222                                                    ren1->pair->one->mode, src);
1223                                }
1224                                conflict_rename_rename(ren1, branch1, ren2, branch2);
1225                        } else {
1226                                struct merge_file_info mfi;
1227                                remove_file(1, ren1_src, 1);
1228                                mfi = merge_file(ren1->pair->one,
1229                                                 ren1->pair->two,
1230                                                 ren2->pair->two,
1231                                                 branch1,
1232                                                 branch2);
1233                                if (mfi.merge || !mfi.clean)
1234                                        output(1, "Renamed %s->%s", src, ren1_dst);
1235
1236                                if (mfi.merge)
1237                                        output(2, "Auto-merged %s", ren1_dst);
1238
1239                                if (!mfi.clean) {
1240                                        output(1, "CONFLICT (content): merge conflict in %s",
1241                                               ren1_dst);
1242                                        clean_merge = 0;
1243
1244                                        if (!index_only)
1245                                                update_stages(ren1_dst,
1246                                                              ren1->pair->one,
1247                                                              ren1->pair->two,
1248                                                              ren2->pair->two,
1249                                                              1 /* clear */);
1250                                }
1251                                update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1252                        }
1253                } else {
1254                        /* Renamed in 1, maybe changed in 2 */
1255                        struct path_list_item *item;
1256                        /* we only use sha1 and mode of these */
1257                        struct diff_filespec src_other, dst_other;
1258                        int try_merge, stage = a_renames == renames1 ? 3: 2;
1259
1260                        remove_file(1, ren1_src, index_only || stage == 3);
1261
1262                        hashcpy(src_other.sha1, ren1->src_entry->stages[stage].sha);
1263                        src_other.mode = ren1->src_entry->stages[stage].mode;
1264                        hashcpy(dst_other.sha1, ren1->dst_entry->stages[stage].sha);
1265                        dst_other.mode = ren1->dst_entry->stages[stage].mode;
1266
1267                        try_merge = 0;
1268
1269                        if (path_list_has_path(&current_directory_set, ren1_dst)) {
1270                                clean_merge = 0;
1271                                output(1, "CONFLICT (rename/directory): Renamed %s->%s in %s "
1272                                       " directory %s added in %s",
1273                                       ren1_src, ren1_dst, branch1,
1274                                       ren1_dst, branch2);
1275                                conflict_rename_dir(ren1, branch1);
1276                        } else if (sha_eq(src_other.sha1, null_sha1)) {
1277                                clean_merge = 0;
1278                                output(1, "CONFLICT (rename/delete): Renamed %s->%s in %s "
1279                                       "and deleted in %s",
1280                                       ren1_src, ren1_dst, branch1,
1281                                       branch2);
1282                                update_file(0, ren1->pair->two->sha1, ren1->pair->two->mode, ren1_dst);
1283                        } else if (!sha_eq(dst_other.sha1, null_sha1)) {
1284                                const char *new_path;
1285                                clean_merge = 0;
1286                                try_merge = 1;
1287                                output(1, "CONFLICT (rename/add): Renamed %s->%s in %s. "
1288                                       "%s added in %s",
1289                                       ren1_src, ren1_dst, branch1,
1290                                       ren1_dst, branch2);
1291                                new_path = unique_path(ren1_dst, branch2);
1292                                output(1, "Added as %s instead", new_path);
1293                                update_file(0, dst_other.sha1, dst_other.mode, new_path);
1294                        } else if ((item = path_list_lookup(ren1_dst, renames2Dst))) {
1295                                ren2 = item->util;
1296                                clean_merge = 0;
1297                                ren2->processed = 1;
1298                                output(1, "CONFLICT (rename/rename): Renamed %s->%s in %s. "
1299                                       "Renamed %s->%s in %s",
1300                                       ren1_src, ren1_dst, branch1,
1301                                       ren2->pair->one->path, ren2->pair->two->path, branch2);
1302                                conflict_rename_rename_2(ren1, branch1, ren2, branch2);
1303                        } else
1304                                try_merge = 1;
1305
1306                        if (try_merge) {
1307                                struct diff_filespec *o, *a, *b;
1308                                struct merge_file_info mfi;
1309                                src_other.path = (char *)ren1_src;
1310
1311                                o = ren1->pair->one;
1312                                if (a_renames == renames1) {
1313                                        a = ren1->pair->two;
1314                                        b = &src_other;
1315                                } else {
1316                                        b = ren1->pair->two;
1317                                        a = &src_other;
1318                                }
1319                                mfi = merge_file(o, a, b,
1320                                                a_branch, b_branch);
1321
1322                                if (mfi.clean &&
1323                                    sha_eq(mfi.sha, ren1->pair->two->sha1) &&
1324                                    mfi.mode == ren1->pair->two->mode)
1325                                        /*
1326                                         * This messaged is part of
1327                                         * t6022 test. If you change
1328                                         * it update the test too.
1329                                         */
1330                                        output(3, "Skipped %s (merged same as existing)", ren1_dst);
1331                                else {
1332                                        if (mfi.merge || !mfi.clean)
1333                                                output(1, "Renamed %s => %s", ren1_src, ren1_dst);
1334                                        if (mfi.merge)
1335                                                output(2, "Auto-merged %s", ren1_dst);
1336                                        if (!mfi.clean) {
1337                                                output(1, "CONFLICT (rename/modify): Merge conflict in %s",
1338                                                       ren1_dst);
1339                                                clean_merge = 0;
1340
1341                                                if (!index_only)
1342                                                        update_stages(ren1_dst,
1343                                                                      o, a, b, 1);
1344                                        }
1345                                        update_file(mfi.clean, mfi.sha, mfi.mode, ren1_dst);
1346                                }
1347                        }
1348                }
1349        }
1350        path_list_clear(&a_by_dst, 0);
1351        path_list_clear(&b_by_dst, 0);
1352
1353        return clean_merge;
1354}
1355
1356static unsigned char *stage_sha(const unsigned char *sha, unsigned mode)
1357{
1358        return (is_null_sha1(sha) || mode == 0) ? NULL: (unsigned char *)sha;
1359}
1360
1361/* Per entry merge function */
1362static int process_entry(const char *path, struct stage_data *entry,
1363                         const char *branch1,
1364                         const char *branch2)
1365{
1366        /*
1367        printf("processing entry, clean cache: %s\n", index_only ? "yes": "no");
1368        print_index_entry("\tpath: ", entry);
1369        */
1370        int clean_merge = 1;
1371        unsigned o_mode = entry->stages[1].mode;
1372        unsigned a_mode = entry->stages[2].mode;
1373        unsigned b_mode = entry->stages[3].mode;
1374        unsigned char *o_sha = stage_sha(entry->stages[1].sha, o_mode);
1375        unsigned char *a_sha = stage_sha(entry->stages[2].sha, a_mode);
1376        unsigned char *b_sha = stage_sha(entry->stages[3].sha, b_mode);
1377
1378        if (o_sha && (!a_sha || !b_sha)) {
1379                /* Case A: Deleted in one */
1380                if ((!a_sha && !b_sha) ||
1381                    (sha_eq(a_sha, o_sha) && !b_sha) ||
1382                    (!a_sha && sha_eq(b_sha, o_sha))) {
1383                        /* Deleted in both or deleted in one and
1384                         * unchanged in the other */
1385                        if (a_sha)
1386                                output(2, "Removed %s", path);
1387                        /* do not touch working file if it did not exist */
1388                        remove_file(1, path, !a_sha);
1389                } else {
1390                        /* Deleted in one and changed in the other */
1391                        clean_merge = 0;
1392                        if (!a_sha) {
1393                                output(1, "CONFLICT (delete/modify): %s deleted in %s "
1394                                       "and modified in %s. Version %s of %s left in tree.",
1395                                       path, branch1,
1396                                       branch2, branch2, path);
1397                                update_file(0, b_sha, b_mode, path);
1398                        } else {
1399                                output(1, "CONFLICT (delete/modify): %s deleted in %s "
1400                                       "and modified in %s. Version %s of %s left in tree.",
1401                                       path, branch2,
1402                                       branch1, branch1, path);
1403                                update_file(0, a_sha, a_mode, path);
1404                        }
1405                }
1406
1407        } else if ((!o_sha && a_sha && !b_sha) ||
1408                   (!o_sha && !a_sha && b_sha)) {
1409                /* Case B: Added in one. */
1410                const char *add_branch;
1411                const char *other_branch;
1412                unsigned mode;
1413                const unsigned char *sha;
1414                const char *conf;
1415
1416                if (a_sha) {
1417                        add_branch = branch1;
1418                        other_branch = branch2;
1419                        mode = a_mode;
1420                        sha = a_sha;
1421                        conf = "file/directory";
1422                } else {
1423                        add_branch = branch2;
1424                        other_branch = branch1;
1425                        mode = b_mode;
1426                        sha = b_sha;
1427                        conf = "directory/file";
1428                }
1429                if (path_list_has_path(&current_directory_set, path)) {
1430                        const char *new_path = unique_path(path, add_branch);
1431                        clean_merge = 0;
1432                        output(1, "CONFLICT (%s): There is a directory with name %s in %s. "
1433                               "Added %s as %s",
1434                               conf, path, other_branch, path, new_path);
1435                        remove_file(0, path, 0);
1436                        update_file(0, sha, mode, new_path);
1437                } else {
1438                        output(2, "Added %s", path);
1439                        update_file(1, sha, mode, path);
1440                }
1441        } else if (a_sha && b_sha) {
1442                /* Case C: Added in both (check for same permissions) and */
1443                /* case D: Modified in both, but differently. */
1444                const char *reason = "content";
1445                struct merge_file_info mfi;
1446                struct diff_filespec o, a, b;
1447
1448                if (!o_sha) {
1449                        reason = "add/add";
1450                        o_sha = (unsigned char *)null_sha1;
1451                }
1452                output(2, "Auto-merged %s", path);
1453                o.path = a.path = b.path = (char *)path;
1454                hashcpy(o.sha1, o_sha);
1455                o.mode = o_mode;
1456                hashcpy(a.sha1, a_sha);
1457                a.mode = a_mode;
1458                hashcpy(b.sha1, b_sha);
1459                b.mode = b_mode;
1460
1461                mfi = merge_file(&o, &a, &b,
1462                                 branch1, branch2);
1463
1464                if (mfi.clean)
1465                        update_file(1, mfi.sha, mfi.mode, path);
1466                else {
1467                        clean_merge = 0;
1468                        output(1, "CONFLICT (%s): Merge conflict in %s",
1469                                        reason, path);
1470
1471                        if (index_only)
1472                                update_file(0, mfi.sha, mfi.mode, path);
1473                        else
1474                                update_file_flags(mfi.sha, mfi.mode, path,
1475                                              0 /* update_cache */, 1 /* update_working_directory */);
1476                }
1477        } else if (!o_sha && !a_sha && !b_sha) {
1478                /*
1479                 * this entry was deleted altogether. a_mode == 0 means
1480                 * we had that path and want to actively remove it.
1481                 */
1482                remove_file(1, path, !a_mode);
1483        } else
1484                die("Fatal merge failure, shouldn't happen.");
1485
1486        return clean_merge;
1487}
1488
1489static int merge_trees(struct tree *head,
1490                       struct tree *merge,
1491                       struct tree *common,
1492                       const char *branch1,
1493                       const char *branch2,
1494                       struct tree **result)
1495{
1496        int code, clean;
1497
1498        if (subtree_merge) {
1499                merge = shift_tree_object(head, merge);
1500                common = shift_tree_object(head, common);
1501        }
1502
1503        if (sha_eq(common->object.sha1, merge->object.sha1)) {
1504                output(0, "Already uptodate!");
1505                *result = head;
1506                return 1;
1507        }
1508
1509        code = git_merge_trees(index_only, common, head, merge);
1510
1511        if (code != 0)
1512                die("merging of trees %s and %s failed",
1513                    sha1_to_hex(head->object.sha1),
1514                    sha1_to_hex(merge->object.sha1));
1515
1516        if (unmerged_index()) {
1517                struct path_list *entries, *re_head, *re_merge;
1518                int i;
1519                path_list_clear(&current_file_set, 1);
1520                path_list_clear(&current_directory_set, 1);
1521                get_files_dirs(head);
1522                get_files_dirs(merge);
1523
1524                entries = get_unmerged();
1525                re_head  = get_renames(head, common, head, merge, entries);
1526                re_merge = get_renames(merge, common, head, merge, entries);
1527                clean = process_renames(re_head, re_merge,
1528                                branch1, branch2);
1529                for (i = 0; i < entries->nr; i++) {
1530                        const char *path = entries->items[i].path;
1531                        struct stage_data *e = entries->items[i].util;
1532                        if (!e->processed
1533                                && !process_entry(path, e, branch1, branch2))
1534                                clean = 0;
1535                }
1536
1537                path_list_clear(re_merge, 0);
1538                path_list_clear(re_head, 0);
1539                path_list_clear(entries, 1);
1540
1541        }
1542        else
1543                clean = 1;
1544
1545        if (index_only)
1546                *result = git_write_tree();
1547
1548        return clean;
1549}
1550
1551static struct commit_list *reverse_commit_list(struct commit_list *list)
1552{
1553        struct commit_list *next = NULL, *current, *backup;
1554        for (current = list; current; current = backup) {
1555                backup = current->next;
1556                current->next = next;
1557                next = current;
1558        }
1559        return next;
1560}
1561
1562/*
1563 * Merge the commits h1 and h2, return the resulting virtual
1564 * commit object and a flag indicating the cleanness of the merge.
1565 */
1566static int merge(struct commit *h1,
1567                 struct commit *h2,
1568                 const char *branch1,
1569                 const char *branch2,
1570                 struct commit_list *ca,
1571                 struct commit **result)
1572{
1573        struct commit_list *iter;
1574        struct commit *merged_common_ancestors;
1575        struct tree *mrtree = mrtree;
1576        int clean;
1577
1578        if (show(4)) {
1579                output(4, "Merging:");
1580                output_commit_title(h1);
1581                output_commit_title(h2);
1582        }
1583
1584        if (!ca) {
1585                ca = get_merge_bases(h1, h2, 1);
1586                ca = reverse_commit_list(ca);
1587        }
1588
1589        if (show(5)) {
1590                output(5, "found %u common ancestor(s):", commit_list_count(ca));
1591                for (iter = ca; iter; iter = iter->next)
1592                        output_commit_title(iter->item);
1593        }
1594
1595        merged_common_ancestors = pop_commit(&ca);
1596        if (merged_common_ancestors == NULL) {
1597                /* if there is no common ancestor, make an empty tree */
1598                struct tree *tree = xcalloc(1, sizeof(struct tree));
1599
1600                tree->object.parsed = 1;
1601                tree->object.type = OBJ_TREE;
1602                pretend_sha1_file(NULL, 0, OBJ_TREE, tree->object.sha1);
1603                merged_common_ancestors = make_virtual_commit(tree, "ancestor");
1604        }
1605
1606        for (iter = ca; iter; iter = iter->next) {
1607                call_depth++;
1608                /*
1609                 * When the merge fails, the result contains files
1610                 * with conflict markers. The cleanness flag is
1611                 * ignored, it was never actually used, as result of
1612                 * merge_trees has always overwritten it: the committed
1613                 * "conflicts" were already resolved.
1614                 */
1615                discard_cache();
1616                merge(merged_common_ancestors, iter->item,
1617                      "Temporary merge branch 1",
1618                      "Temporary merge branch 2",
1619                      NULL,
1620                      &merged_common_ancestors);
1621                call_depth--;
1622
1623                if (!merged_common_ancestors)
1624                        die("merge returned no commit");
1625        }
1626
1627        discard_cache();
1628        if (!call_depth) {
1629                read_cache();
1630                index_only = 0;
1631        } else
1632                index_only = 1;
1633
1634        clean = merge_trees(h1->tree, h2->tree, merged_common_ancestors->tree,
1635                            branch1, branch2, &mrtree);
1636
1637        if (index_only) {
1638                *result = make_virtual_commit(mrtree, "merged tree");
1639                commit_list_insert(h1, &(*result)->parents);
1640                commit_list_insert(h2, &(*result)->parents->next);
1641        }
1642        flush_output();
1643        return clean;
1644}
1645
1646static const char *better_branch_name(const char *branch)
1647{
1648        static char githead_env[8 + 40 + 1];
1649        char *name;
1650
1651        if (strlen(branch) != 40)
1652                return branch;
1653        sprintf(githead_env, "GITHEAD_%s", branch);
1654        name = getenv(githead_env);
1655        return name ? name : branch;
1656}
1657
1658static struct commit *get_ref(const char *ref)
1659{
1660        unsigned char sha1[20];
1661        struct object *object;
1662
1663        if (get_sha1(ref, sha1))
1664                die("Could not resolve ref '%s'", ref);
1665        object = deref_tag(parse_object(sha1), ref, strlen(ref));
1666        if (object->type == OBJ_TREE)
1667                return make_virtual_commit((struct tree*)object,
1668                        better_branch_name(ref));
1669        if (object->type != OBJ_COMMIT)
1670                return NULL;
1671        if (parse_commit((struct commit *)object))
1672                die("Could not parse commit '%s'", sha1_to_hex(object->sha1));
1673        return (struct commit *)object;
1674}
1675
1676static int merge_config(const char *var, const char *value)
1677{
1678        if (!strcasecmp(var, "merge.verbosity")) {
1679                verbosity = git_config_int(var, value);
1680                return 0;
1681        }
1682        if (!strcasecmp(var, "diff.renamelimit")) {
1683                rename_limit = git_config_int(var, value);
1684                return 0;
1685        }
1686        return git_default_config(var, value);
1687}
1688
1689int main(int argc, char *argv[])
1690{
1691        static const char *bases[20];
1692        static unsigned bases_count = 0;
1693        int i, clean;
1694        const char *branch1, *branch2;
1695        struct commit *result, *h1, *h2;
1696        struct commit_list *ca = NULL;
1697        struct lock_file *lock = xcalloc(1, sizeof(struct lock_file));
1698        int index_fd;
1699
1700        if (argv[0]) {
1701                int namelen = strlen(argv[0]);
1702                if (8 < namelen &&
1703                    !strcmp(argv[0] + namelen - 8, "-subtree"))
1704                        subtree_merge = 1;
1705        }
1706
1707        git_config(merge_config);
1708        if (getenv("GIT_MERGE_VERBOSITY"))
1709                verbosity = strtol(getenv("GIT_MERGE_VERBOSITY"), NULL, 10);
1710
1711        if (argc < 4)
1712                die("Usage: %s <base>... -- <head> <remote> ...\n", argv[0]);
1713
1714        for (i = 1; i < argc; ++i) {
1715                if (!strcmp(argv[i], "--"))
1716                        break;
1717                if (bases_count < sizeof(bases)/sizeof(*bases))
1718                        bases[bases_count++] = argv[i];
1719        }
1720        if (argc - i != 3) /* "--" "<head>" "<remote>" */
1721                die("Not handling anything other than two heads merge.");
1722        if (verbosity >= 5)
1723                buffer_output = 0;
1724
1725        branch1 = argv[++i];
1726        branch2 = argv[++i];
1727
1728        h1 = get_ref(branch1);
1729        h2 = get_ref(branch2);
1730
1731        branch1 = better_branch_name(branch1);
1732        branch2 = better_branch_name(branch2);
1733
1734        if (show(3))
1735                printf("Merging %s with %s\n", branch1, branch2);
1736
1737        index_fd = hold_locked_index(lock, 1);
1738
1739        for (i = 0; i < bases_count; i++) {
1740                struct commit *ancestor = get_ref(bases[i]);
1741                ca = commit_list_insert(ancestor, &ca);
1742        }
1743        clean = merge(h1, h2, branch1, branch2, ca, &result);
1744
1745        if (active_cache_changed &&
1746            (write_cache(index_fd, active_cache, active_nr) ||
1747             close(index_fd) || commit_locked_index(lock)))
1748                        die ("unable to write %s", get_index_file());
1749
1750        return clean ? 0: 1;
1751}