rerere.con commit Merge branch 'jc/makefile-redirection-stderr' into maint (98eef48)
   1#include "cache.h"
   2#include "lockfile.h"
   3#include "string-list.h"
   4#include "rerere.h"
   5#include "xdiff-interface.h"
   6#include "dir.h"
   7#include "resolve-undo.h"
   8#include "ll-merge.h"
   9#include "attr.h"
  10#include "pathspec.h"
  11
  12#define RESOLVED 0
  13#define PUNTED 1
  14#define THREE_STAGED 2
  15void *RERERE_RESOLVED = &RERERE_RESOLVED;
  16
  17/* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
  18static int rerere_enabled = -1;
  19
  20/* automatically update cleanly resolved paths to the index */
  21static int rerere_autoupdate;
  22
  23static void free_rerere_id(struct string_list_item *item)
  24{
  25        free(item->util);
  26}
  27
  28static const char *rerere_id_hex(const struct rerere_id *id)
  29{
  30        return id->hex;
  31}
  32
  33const char *rerere_path(const struct rerere_id *id, const char *file)
  34{
  35        if (!file)
  36                return git_path("rr-cache/%s", rerere_id_hex(id));
  37
  38        return git_path("rr-cache/%s/%s", rerere_id_hex(id), file);
  39}
  40
  41static int has_rerere_resolution(const struct rerere_id *id)
  42{
  43        struct stat st;
  44
  45        return !stat(rerere_path(id, "postimage"), &st);
  46}
  47
  48static struct rerere_id *new_rerere_id_hex(char *hex)
  49{
  50        struct rerere_id *id = xmalloc(sizeof(*id));
  51        xsnprintf(id->hex, sizeof(id->hex), "%s", hex);
  52        return id;
  53}
  54
  55static struct rerere_id *new_rerere_id(unsigned char *sha1)
  56{
  57        return new_rerere_id_hex(sha1_to_hex(sha1));
  58}
  59
  60/*
  61 * $GIT_DIR/MERGE_RR file is a collection of records, each of which is
  62 * "conflict ID", a HT and pathname, terminated with a NUL, and is
  63 * used to keep track of the set of paths that "rerere" may need to
  64 * work on (i.e. what is left by the previous invocation of "git
  65 * rerere" during the current conflict resolution session).
  66 */
  67static void read_rr(struct string_list *rr)
  68{
  69        struct strbuf buf = STRBUF_INIT;
  70        FILE *in = fopen(git_path_merge_rr(), "r");
  71
  72        if (!in)
  73                return;
  74        while (!strbuf_getwholeline(&buf, in, '\0')) {
  75                char *path;
  76                unsigned char sha1[20];
  77                struct rerere_id *id;
  78
  79                /* There has to be the hash, tab, path and then NUL */
  80                if (buf.len < 42 || get_sha1_hex(buf.buf, sha1))
  81                        die("corrupt MERGE_RR");
  82
  83                if (buf.buf[40] != '\t')
  84                        die("corrupt MERGE_RR");
  85                buf.buf[40] = '\0';
  86                path = buf.buf + 41;
  87                id = new_rerere_id_hex(buf.buf);
  88                string_list_insert(rr, path)->util = id;
  89        }
  90        strbuf_release(&buf);
  91        fclose(in);
  92}
  93
  94static struct lock_file write_lock;
  95
  96static int write_rr(struct string_list *rr, int out_fd)
  97{
  98        int i;
  99        for (i = 0; i < rr->nr; i++) {
 100                struct strbuf buf = STRBUF_INIT;
 101                struct rerere_id *id;
 102
 103                assert(rr->items[i].util != RERERE_RESOLVED);
 104
 105                id = rr->items[i].util;
 106                if (!id)
 107                        continue;
 108                strbuf_addf(&buf, "%s\t%s%c",
 109                            rerere_id_hex(id),
 110                            rr->items[i].string, 0);
 111                if (write_in_full(out_fd, buf.buf, buf.len) != buf.len)
 112                        die("unable to write rerere record");
 113
 114                strbuf_release(&buf);
 115        }
 116        if (commit_lock_file(&write_lock) != 0)
 117                die("unable to write rerere record");
 118        return 0;
 119}
 120
 121/*
 122 * "rerere" interacts with conflicted file contents using this I/O
 123 * abstraction.  It reads a conflicted contents from one place via
 124 * "getline()" method, and optionally can write it out after
 125 * normalizing the conflicted hunks to the "output".  Subclasses of
 126 * rerere_io embed this structure at the beginning of their own
 127 * rerere_io object.
 128 */
 129struct rerere_io {
 130        int (*getline)(struct strbuf *, struct rerere_io *);
 131        FILE *output;
 132        int wrerror;
 133        /* some more stuff */
 134};
 135
 136static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
 137{
 138        if (!count || *err)
 139                return;
 140        if (fwrite(p, count, 1, fp) != 1)
 141                *err = errno;
 142}
 143
 144static inline void ferr_puts(const char *s, FILE *fp, int *err)
 145{
 146        ferr_write(s, strlen(s), fp, err);
 147}
 148
 149static void rerere_io_putstr(const char *str, struct rerere_io *io)
 150{
 151        if (io->output)
 152                ferr_puts(str, io->output, &io->wrerror);
 153}
 154
 155/*
 156 * Write a conflict marker to io->output (if defined).
 157 */
 158static void rerere_io_putconflict(int ch, int size, struct rerere_io *io)
 159{
 160        char buf[64];
 161
 162        while (size) {
 163                if (size <= sizeof(buf) - 2) {
 164                        memset(buf, ch, size);
 165                        buf[size] = '\n';
 166                        buf[size + 1] = '\0';
 167                        size = 0;
 168                } else {
 169                        int sz = sizeof(buf) - 1;
 170
 171                        /*
 172                         * Make sure we will not write everything out
 173                         * in this round by leaving at least 1 byte
 174                         * for the next round, giving the next round
 175                         * a chance to add the terminating LF.  Yuck.
 176                         */
 177                        if (size <= sz)
 178                                sz -= (sz - size) + 1;
 179                        memset(buf, ch, sz);
 180                        buf[sz] = '\0';
 181                        size -= sz;
 182                }
 183                rerere_io_putstr(buf, io);
 184        }
 185}
 186
 187static void rerere_io_putmem(const char *mem, size_t sz, struct rerere_io *io)
 188{
 189        if (io->output)
 190                ferr_write(mem, sz, io->output, &io->wrerror);
 191}
 192
 193/*
 194 * Subclass of rerere_io that reads from an on-disk file
 195 */
 196struct rerere_io_file {
 197        struct rerere_io io;
 198        FILE *input;
 199};
 200
 201/*
 202 * ... and its getline() method implementation
 203 */
 204static int rerere_file_getline(struct strbuf *sb, struct rerere_io *io_)
 205{
 206        struct rerere_io_file *io = (struct rerere_io_file *)io_;
 207        return strbuf_getwholeline(sb, io->input, '\n');
 208}
 209
 210/*
 211 * Require the exact number of conflict marker letters, no more, no
 212 * less, followed by SP or any whitespace
 213 * (including LF).
 214 */
 215static int is_cmarker(char *buf, int marker_char, int marker_size)
 216{
 217        int want_sp;
 218
 219        /*
 220         * The beginning of our version and the end of their version
 221         * always are labeled like "<<<<< ours" or ">>>>> theirs",
 222         * hence we set want_sp for them.  Note that the version from
 223         * the common ancestor in diff3-style output is not always
 224         * labelled (e.g. "||||| common" is often seen but "|||||"
 225         * alone is also valid), so we do not set want_sp.
 226         */
 227        want_sp = (marker_char == '<') || (marker_char == '>');
 228
 229        while (marker_size--)
 230                if (*buf++ != marker_char)
 231                        return 0;
 232        if (want_sp && *buf != ' ')
 233                return 0;
 234        return isspace(*buf);
 235}
 236
 237/*
 238 * Read contents a file with conflicts, normalize the conflicts
 239 * by (1) discarding the common ancestor version in diff3-style,
 240 * (2) reordering our side and their side so that whichever sorts
 241 * alphabetically earlier comes before the other one, while
 242 * computing the "conflict ID", which is just an SHA-1 hash of
 243 * one side of the conflict, NUL, the other side of the conflict,
 244 * and NUL concatenated together.
 245 *
 246 * Return the number of conflict hunks found.
 247 *
 248 * NEEDSWORK: the logic and theory of operation behind this conflict
 249 * normalization may deserve to be documented somewhere, perhaps in
 250 * Documentation/technical/rerere.txt.
 251 */
 252static int handle_path(unsigned char *sha1, struct rerere_io *io, int marker_size)
 253{
 254        git_SHA_CTX ctx;
 255        int hunk_no = 0;
 256        enum {
 257                RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL
 258        } hunk = RR_CONTEXT;
 259        struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
 260        struct strbuf buf = STRBUF_INIT;
 261
 262        if (sha1)
 263                git_SHA1_Init(&ctx);
 264
 265        while (!io->getline(&buf, io)) {
 266                if (is_cmarker(buf.buf, '<', marker_size)) {
 267                        if (hunk != RR_CONTEXT)
 268                                goto bad;
 269                        hunk = RR_SIDE_1;
 270                } else if (is_cmarker(buf.buf, '|', marker_size)) {
 271                        if (hunk != RR_SIDE_1)
 272                                goto bad;
 273                        hunk = RR_ORIGINAL;
 274                } else if (is_cmarker(buf.buf, '=', marker_size)) {
 275                        if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
 276                                goto bad;
 277                        hunk = RR_SIDE_2;
 278                } else if (is_cmarker(buf.buf, '>', marker_size)) {
 279                        if (hunk != RR_SIDE_2)
 280                                goto bad;
 281                        if (strbuf_cmp(&one, &two) > 0)
 282                                strbuf_swap(&one, &two);
 283                        hunk_no++;
 284                        hunk = RR_CONTEXT;
 285                        rerere_io_putconflict('<', marker_size, io);
 286                        rerere_io_putmem(one.buf, one.len, io);
 287                        rerere_io_putconflict('=', marker_size, io);
 288                        rerere_io_putmem(two.buf, two.len, io);
 289                        rerere_io_putconflict('>', marker_size, io);
 290                        if (sha1) {
 291                                git_SHA1_Update(&ctx, one.buf ? one.buf : "",
 292                                            one.len + 1);
 293                                git_SHA1_Update(&ctx, two.buf ? two.buf : "",
 294                                            two.len + 1);
 295                        }
 296                        strbuf_reset(&one);
 297                        strbuf_reset(&two);
 298                } else if (hunk == RR_SIDE_1)
 299                        strbuf_addbuf(&one, &buf);
 300                else if (hunk == RR_ORIGINAL)
 301                        ; /* discard */
 302                else if (hunk == RR_SIDE_2)
 303                        strbuf_addbuf(&two, &buf);
 304                else
 305                        rerere_io_putstr(buf.buf, io);
 306                continue;
 307        bad:
 308                hunk = 99; /* force error exit */
 309                break;
 310        }
 311        strbuf_release(&one);
 312        strbuf_release(&two);
 313        strbuf_release(&buf);
 314
 315        if (sha1)
 316                git_SHA1_Final(sha1, &ctx);
 317        if (hunk != RR_CONTEXT)
 318                return -1;
 319        return hunk_no;
 320}
 321
 322/*
 323 * Scan the path for conflicts, do the "handle_path()" thing above, and
 324 * return the number of conflict hunks found.
 325 */
 326static int handle_file(const char *path, unsigned char *sha1, const char *output)
 327{
 328        int hunk_no = 0;
 329        struct rerere_io_file io;
 330        int marker_size = ll_merge_marker_size(path);
 331
 332        memset(&io, 0, sizeof(io));
 333        io.io.getline = rerere_file_getline;
 334        io.input = fopen(path, "r");
 335        io.io.wrerror = 0;
 336        if (!io.input)
 337                return error("Could not open %s", path);
 338
 339        if (output) {
 340                io.io.output = fopen(output, "w");
 341                if (!io.io.output) {
 342                        fclose(io.input);
 343                        return error("Could not write %s", output);
 344                }
 345        }
 346
 347        hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
 348
 349        fclose(io.input);
 350        if (io.io.wrerror)
 351                error("There were errors while writing %s (%s)",
 352                      path, strerror(io.io.wrerror));
 353        if (io.io.output && fclose(io.io.output))
 354                io.io.wrerror = error("Failed to flush %s: %s",
 355                                      path, strerror(errno));
 356
 357        if (hunk_no < 0) {
 358                if (output)
 359                        unlink_or_warn(output);
 360                return error("Could not parse conflict hunks in %s", path);
 361        }
 362        if (io.io.wrerror)
 363                return -1;
 364        return hunk_no;
 365}
 366
 367/*
 368 * Subclass of rerere_io that reads from an in-core buffer that is a
 369 * strbuf
 370 */
 371struct rerere_io_mem {
 372        struct rerere_io io;
 373        struct strbuf input;
 374};
 375
 376/*
 377 * ... and its getline() method implementation
 378 */
 379static int rerere_mem_getline(struct strbuf *sb, struct rerere_io *io_)
 380{
 381        struct rerere_io_mem *io = (struct rerere_io_mem *)io_;
 382        char *ep;
 383        size_t len;
 384
 385        strbuf_release(sb);
 386        if (!io->input.len)
 387                return -1;
 388        ep = memchr(io->input.buf, '\n', io->input.len);
 389        if (!ep)
 390                ep = io->input.buf + io->input.len;
 391        else if (*ep == '\n')
 392                ep++;
 393        len = ep - io->input.buf;
 394        strbuf_add(sb, io->input.buf, len);
 395        strbuf_remove(&io->input, 0, len);
 396        return 0;
 397}
 398
 399static int handle_cache(const char *path, unsigned char *sha1, const char *output)
 400{
 401        mmfile_t mmfile[3] = {{NULL}};
 402        mmbuffer_t result = {NULL, 0};
 403        const struct cache_entry *ce;
 404        int pos, len, i, hunk_no;
 405        struct rerere_io_mem io;
 406        int marker_size = ll_merge_marker_size(path);
 407
 408        /*
 409         * Reproduce the conflicted merge in-core
 410         */
 411        len = strlen(path);
 412        pos = cache_name_pos(path, len);
 413        if (0 <= pos)
 414                return -1;
 415        pos = -pos - 1;
 416
 417        while (pos < active_nr) {
 418                enum object_type type;
 419                unsigned long size;
 420
 421                ce = active_cache[pos++];
 422                if (ce_namelen(ce) != len || memcmp(ce->name, path, len))
 423                        break;
 424                i = ce_stage(ce) - 1;
 425                if (!mmfile[i].ptr) {
 426                        mmfile[i].ptr = read_sha1_file(ce->sha1, &type, &size);
 427                        mmfile[i].size = size;
 428                }
 429        }
 430        for (i = 0; i < 3; i++)
 431                if (!mmfile[i].ptr && !mmfile[i].size)
 432                        mmfile[i].ptr = xstrdup("");
 433
 434        /*
 435         * NEEDSWORK: handle conflicts from merges with
 436         * merge.renormalize set, too
 437         */
 438        ll_merge(&result, path, &mmfile[0], NULL,
 439                 &mmfile[1], "ours",
 440                 &mmfile[2], "theirs", NULL);
 441        for (i = 0; i < 3; i++)
 442                free(mmfile[i].ptr);
 443
 444        memset(&io, 0, sizeof(io));
 445        io.io.getline = rerere_mem_getline;
 446        if (output)
 447                io.io.output = fopen(output, "w");
 448        else
 449                io.io.output = NULL;
 450        strbuf_init(&io.input, 0);
 451        strbuf_attach(&io.input, result.ptr, result.size, result.size);
 452
 453        /*
 454         * Grab the conflict ID and optionally write the original
 455         * contents with conflict markers out.
 456         */
 457        hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
 458        strbuf_release(&io.input);
 459        if (io.io.output)
 460                fclose(io.io.output);
 461        return hunk_no;
 462}
 463
 464/*
 465 * Look at a cache entry at "i" and see if it is not conflicting,
 466 * conflicting and we are willing to handle, or conflicting and
 467 * we are unable to handle, and return the determination in *type.
 468 * Return the cache index to be looked at next, by skipping the
 469 * stages we have already looked at in this invocation of this
 470 * function.
 471 */
 472static int check_one_conflict(int i, int *type)
 473{
 474        const struct cache_entry *e = active_cache[i];
 475
 476        if (!ce_stage(e)) {
 477                *type = RESOLVED;
 478                return i + 1;
 479        }
 480
 481        *type = PUNTED;
 482        while (ce_stage(active_cache[i]) == 1)
 483                i++;
 484
 485        /* Only handle regular files with both stages #2 and #3 */
 486        if (i + 1 < active_nr) {
 487                const struct cache_entry *e2 = active_cache[i];
 488                const struct cache_entry *e3 = active_cache[i + 1];
 489                if (ce_stage(e2) == 2 &&
 490                    ce_stage(e3) == 3 &&
 491                    ce_same_name(e, e3) &&
 492                    S_ISREG(e2->ce_mode) &&
 493                    S_ISREG(e3->ce_mode))
 494                        *type = THREE_STAGED;
 495        }
 496
 497        /* Skip the entries with the same name */
 498        while (i < active_nr && ce_same_name(e, active_cache[i]))
 499                i++;
 500        return i;
 501}
 502
 503/*
 504 * Scan the index and find paths that have conflicts that rerere can
 505 * handle, i.e. the ones that has both stages #2 and #3.
 506 *
 507 * NEEDSWORK: we do not record or replay a previous "resolve by
 508 * deletion" for a delete-modify conflict, as that is inherently risky
 509 * without knowing what modification is being discarded.  The only
 510 * safe case, i.e. both side doing the deletion and modification that
 511 * are identical to the previous round, might want to be handled,
 512 * though.
 513 */
 514static int find_conflict(struct string_list *conflict)
 515{
 516        int i;
 517        if (read_cache() < 0)
 518                return error("Could not read index");
 519
 520        for (i = 0; i < active_nr;) {
 521                int conflict_type;
 522                const struct cache_entry *e = active_cache[i];
 523                i = check_one_conflict(i, &conflict_type);
 524                if (conflict_type == THREE_STAGED)
 525                        string_list_insert(conflict, (const char *)e->name);
 526        }
 527        return 0;
 528}
 529
 530/*
 531 * The merge_rr list is meant to hold outstanding conflicted paths
 532 * that rerere could handle.  Abuse the list by adding other types of
 533 * entries to allow the caller to show "rerere remaining".
 534 *
 535 * - Conflicted paths that rerere does not handle are added
 536 * - Conflicted paths that have been resolved are marked as such
 537 *   by storing RERERE_RESOLVED to .util field (where conflict ID
 538 *   is expected to be stored).
 539 *
 540 * Do *not* write MERGE_RR file out after calling this function.
 541 *
 542 * NEEDSWORK: we may want to fix the caller that implements "rerere
 543 * remaining" to do this without abusing merge_rr.
 544 */
 545int rerere_remaining(struct string_list *merge_rr)
 546{
 547        int i;
 548        if (setup_rerere(merge_rr, RERERE_READONLY))
 549                return 0;
 550        if (read_cache() < 0)
 551                return error("Could not read index");
 552
 553        for (i = 0; i < active_nr;) {
 554                int conflict_type;
 555                const struct cache_entry *e = active_cache[i];
 556                i = check_one_conflict(i, &conflict_type);
 557                if (conflict_type == PUNTED)
 558                        string_list_insert(merge_rr, (const char *)e->name);
 559                else if (conflict_type == RESOLVED) {
 560                        struct string_list_item *it;
 561                        it = string_list_lookup(merge_rr, (const char *)e->name);
 562                        if (it != NULL) {
 563                                free_rerere_id(it);
 564                                it->util = RERERE_RESOLVED;
 565                        }
 566                }
 567        }
 568        return 0;
 569}
 570
 571/*
 572 * Find the conflict identified by "id"; the change between its
 573 * "preimage" (i.e. a previous contents with conflict markers) and its
 574 * "postimage" (i.e. the corresponding contents with conflicts
 575 * resolved) may apply cleanly to the contents stored in "path", i.e.
 576 * the conflict this time around.
 577 *
 578 * Returns 0 for successful replay of recorded resolution, or non-zero
 579 * for failure.
 580 */
 581static int merge(const struct rerere_id *id, const char *path)
 582{
 583        FILE *f;
 584        int ret;
 585        mmfile_t cur = {NULL, 0}, base = {NULL, 0}, other = {NULL, 0};
 586        mmbuffer_t result = {NULL, 0};
 587
 588        /*
 589         * Normalize the conflicts in path and write it out to
 590         * "thisimage" temporary file.
 591         */
 592        if (handle_file(path, NULL, rerere_path(id, "thisimage")) < 0) {
 593                ret = 1;
 594                goto out;
 595        }
 596
 597        if (read_mmfile(&cur, rerere_path(id, "thisimage")) ||
 598            read_mmfile(&base, rerere_path(id, "preimage")) ||
 599            read_mmfile(&other, rerere_path(id, "postimage"))) {
 600                ret = 1;
 601                goto out;
 602        }
 603
 604        /*
 605         * A three-way merge. Note that this honors user-customizable
 606         * low-level merge driver settings.
 607         */
 608        ret = ll_merge(&result, path, &base, NULL, &cur, "", &other, "", NULL);
 609        if (ret)
 610                goto out;
 611
 612        /*
 613         * A successful replay of recorded resolution.
 614         * Mark that "postimage" was used to help gc.
 615         */
 616        if (utime(rerere_path(id, "postimage"), NULL) < 0)
 617                warning("failed utime() on %s: %s",
 618                        rerere_path(id, "postimage"),
 619                        strerror(errno));
 620
 621        /* Update "path" with the resolution */
 622        f = fopen(path, "w");
 623        if (!f)
 624                return error("Could not open %s: %s", path,
 625                             strerror(errno));
 626        if (fwrite(result.ptr, result.size, 1, f) != 1)
 627                error("Could not write %s: %s", path, strerror(errno));
 628        if (fclose(f))
 629                return error("Writing %s failed: %s", path,
 630                             strerror(errno));
 631
 632out:
 633        free(cur.ptr);
 634        free(base.ptr);
 635        free(other.ptr);
 636        free(result.ptr);
 637
 638        return ret;
 639}
 640
 641static struct lock_file index_lock;
 642
 643static void update_paths(struct string_list *update)
 644{
 645        int i;
 646
 647        hold_locked_index(&index_lock, 1);
 648
 649        for (i = 0; i < update->nr; i++) {
 650                struct string_list_item *item = &update->items[i];
 651                if (add_file_to_cache(item->string, 0))
 652                        exit(128);
 653                fprintf(stderr, "Staged '%s' using previous resolution.\n",
 654                        item->string);
 655        }
 656
 657        if (active_cache_changed) {
 658                if (write_locked_index(&the_index, &index_lock, COMMIT_LOCK))
 659                        die("Unable to write new index file");
 660        } else
 661                rollback_lock_file(&index_lock);
 662}
 663
 664/*
 665 * The path indicated by rr_item may still have conflict for which we
 666 * have a recorded resolution, in which case replay it and optionally
 667 * update it.  Or it may have been resolved by the user and we may
 668 * only have the preimage for that conflict, in which case the result
 669 * needs to be recorded as a resolution in a postimage file.
 670 */
 671static void do_rerere_one_path(struct string_list_item *rr_item,
 672                               struct string_list *update)
 673{
 674        const char *path = rr_item->string;
 675        const struct rerere_id *id = rr_item->util;
 676
 677        /* Is there a recorded resolution we could attempt to apply? */
 678        if (has_rerere_resolution(id)) {
 679                if (merge(id, path))
 680                        return; /* failed to replay */
 681
 682                if (rerere_autoupdate)
 683                        string_list_insert(update, path);
 684                else
 685                        fprintf(stderr,
 686                                "Resolved '%s' using previous resolution.\n",
 687                                path);
 688        } else if (!handle_file(path, NULL, NULL)) {
 689                /* The user has resolved it. */
 690                copy_file(rerere_path(id, "postimage"), path, 0666);
 691                fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 692        } else {
 693                return;
 694        }
 695        free_rerere_id(rr_item);
 696        rr_item->util = NULL;
 697}
 698
 699static int do_plain_rerere(struct string_list *rr, int fd)
 700{
 701        struct string_list conflict = STRING_LIST_INIT_DUP;
 702        struct string_list update = STRING_LIST_INIT_DUP;
 703        int i;
 704
 705        find_conflict(&conflict);
 706
 707        /*
 708         * MERGE_RR records paths with conflicts immediately after
 709         * merge failed.  Some of the conflicted paths might have been
 710         * hand resolved in the working tree since then, but the
 711         * initial run would catch all and register their preimages.
 712         */
 713        for (i = 0; i < conflict.nr; i++) {
 714                struct rerere_id *id;
 715                unsigned char sha1[20];
 716                const char *path = conflict.items[i].string;
 717                int ret;
 718
 719                if (string_list_has_string(rr, path))
 720                        continue;
 721
 722                /*
 723                 * Ask handle_file() to scan and assign a
 724                 * conflict ID.  No need to write anything out
 725                 * yet.
 726                 */
 727                ret = handle_file(path, sha1, NULL);
 728                if (ret < 1)
 729                        continue;
 730
 731                id = new_rerere_id(sha1);
 732                string_list_insert(rr, path)->util = id;
 733
 734                /*
 735                 * If the directory does not exist, create
 736                 * it.  mkdir_in_gitdir() will fail with
 737                 * EEXIST if there already is one.
 738                 *
 739                 * NEEDSWORK: make sure "gc" does not remove
 740                 * preimage without removing the directory.
 741                 */
 742                if (mkdir_in_gitdir(rerere_path(id, NULL)))
 743                        continue;
 744
 745                /*
 746                 * We are the first to encounter this
 747                 * conflict.  Ask handle_file() to write the
 748                 * normalized contents to the "preimage" file.
 749                 */
 750                handle_file(path, NULL, rerere_path(id, "preimage"));
 751                fprintf(stderr, "Recorded preimage for '%s'\n", path);
 752        }
 753
 754        for (i = 0; i < rr->nr; i++)
 755                do_rerere_one_path(&rr->items[i], &update);
 756
 757        if (update.nr)
 758                update_paths(&update);
 759
 760        return write_rr(rr, fd);
 761}
 762
 763static void git_rerere_config(void)
 764{
 765        git_config_get_bool("rerere.enabled", &rerere_enabled);
 766        git_config_get_bool("rerere.autoupdate", &rerere_autoupdate);
 767        git_config(git_default_config, NULL);
 768}
 769
 770static GIT_PATH_FUNC(git_path_rr_cache, "rr-cache")
 771
 772static int is_rerere_enabled(void)
 773{
 774        int rr_cache_exists;
 775
 776        if (!rerere_enabled)
 777                return 0;
 778
 779        rr_cache_exists = is_directory(git_path_rr_cache());
 780        if (rerere_enabled < 0)
 781                return rr_cache_exists;
 782
 783        if (!rr_cache_exists && mkdir_in_gitdir(git_path_rr_cache()))
 784                die("Could not create directory %s", git_path_rr_cache());
 785        return 1;
 786}
 787
 788int setup_rerere(struct string_list *merge_rr, int flags)
 789{
 790        int fd;
 791
 792        git_rerere_config();
 793        if (!is_rerere_enabled())
 794                return -1;
 795
 796        if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE))
 797                rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE);
 798        if (flags & RERERE_READONLY)
 799                fd = 0;
 800        else
 801                fd = hold_lock_file_for_update(&write_lock, git_path_merge_rr(),
 802                                               LOCK_DIE_ON_ERROR);
 803        read_rr(merge_rr);
 804        return fd;
 805}
 806
 807/*
 808 * The main entry point that is called internally from codepaths that
 809 * perform mergy operations, possibly leaving conflicted index entries
 810 * and working tree files.
 811 */
 812int rerere(int flags)
 813{
 814        struct string_list merge_rr = STRING_LIST_INIT_DUP;
 815        int fd;
 816
 817        fd = setup_rerere(&merge_rr, flags);
 818        if (fd < 0)
 819                return 0;
 820        return do_plain_rerere(&merge_rr, fd);
 821}
 822
 823static int rerere_forget_one_path(const char *path, struct string_list *rr)
 824{
 825        const char *filename;
 826        struct rerere_id *id;
 827        unsigned char sha1[20];
 828        int ret;
 829        struct string_list_item *item;
 830
 831        /*
 832         * Recreate the original conflict from the stages in the
 833         * index and compute the conflict ID
 834         */
 835        ret = handle_cache(path, sha1, NULL);
 836        if (ret < 1)
 837                return error("Could not parse conflict hunks in '%s'", path);
 838
 839        /* Nuke the recorded resolution for the conflict */
 840        id = new_rerere_id(sha1);
 841        filename = rerere_path(id, "postimage");
 842        if (unlink(filename))
 843                return (errno == ENOENT
 844                        ? error("no remembered resolution for %s", path)
 845                        : error("cannot unlink %s: %s", filename, strerror(errno)));
 846
 847        /*
 848         * Update the preimage so that the user can resolve the
 849         * conflict in the working tree, run us again to record
 850         * the postimage.
 851         */
 852        handle_cache(path, sha1, rerere_path(id, "preimage"));
 853        fprintf(stderr, "Updated preimage for '%s'\n", path);
 854
 855        /*
 856         * And remember that we can record resolution for this
 857         * conflict when the user is done.
 858         */
 859        item = string_list_insert(rr, path);
 860        free_rerere_id(item);
 861        item->util = id;
 862        fprintf(stderr, "Forgot resolution for %s\n", path);
 863        return 0;
 864}
 865
 866int rerere_forget(struct pathspec *pathspec)
 867{
 868        int i, fd;
 869        struct string_list conflict = STRING_LIST_INIT_DUP;
 870        struct string_list merge_rr = STRING_LIST_INIT_DUP;
 871
 872        if (read_cache() < 0)
 873                return error("Could not read index");
 874
 875        fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
 876        if (fd < 0)
 877                return 0;
 878
 879        /*
 880         * The paths may have been resolved (incorrectly);
 881         * recover the original conflicted state and then
 882         * find the conflicted paths.
 883         */
 884        unmerge_cache(pathspec);
 885        find_conflict(&conflict);
 886        for (i = 0; i < conflict.nr; i++) {
 887                struct string_list_item *it = &conflict.items[i];
 888                if (!match_pathspec(pathspec, it->string,
 889                                    strlen(it->string), 0, NULL, 0))
 890                        continue;
 891                rerere_forget_one_path(it->string, &merge_rr);
 892        }
 893        return write_rr(&merge_rr, fd);
 894}
 895
 896/*
 897 * Garbage collection support
 898 */
 899
 900/*
 901 * Note that this is not reentrant but is used only one-at-a-time
 902 * so it does not matter right now.
 903 */
 904static struct rerere_id *dirname_to_id(const char *name)
 905{
 906        static struct rerere_id id;
 907        xsnprintf(id.hex, sizeof(id.hex), "%s", name);
 908        return &id;
 909}
 910
 911static time_t rerere_created_at(const char *dir_name)
 912{
 913        struct stat st;
 914        struct rerere_id *id = dirname_to_id(dir_name);
 915
 916        return stat(rerere_path(id, "preimage"), &st) ? (time_t) 0 : st.st_mtime;
 917}
 918
 919static time_t rerere_last_used_at(const char *dir_name)
 920{
 921        struct stat st;
 922        struct rerere_id *id = dirname_to_id(dir_name);
 923
 924        return stat(rerere_path(id, "postimage"), &st) ? (time_t) 0 : st.st_mtime;
 925}
 926
 927/*
 928 * Remove the recorded resolution for a given conflict ID
 929 */
 930static void unlink_rr_item(struct rerere_id *id)
 931{
 932        unlink(rerere_path(id, "thisimage"));
 933        unlink(rerere_path(id, "preimage"));
 934        unlink(rerere_path(id, "postimage"));
 935        /*
 936         * NEEDSWORK: what if this rmdir() fails?  Wouldn't we then
 937         * assume that we already have preimage recorded in
 938         * do_plain_rerere()?
 939         */
 940        rmdir(rerere_path(id, NULL));
 941}
 942
 943void rerere_gc(struct string_list *rr)
 944{
 945        struct string_list to_remove = STRING_LIST_INIT_DUP;
 946        DIR *dir;
 947        struct dirent *e;
 948        int i, cutoff;
 949        time_t now = time(NULL), then;
 950        int cutoff_noresolve = 15;
 951        int cutoff_resolve = 60;
 952
 953        if (setup_rerere(rr, 0) < 0)
 954                return;
 955
 956        git_config_get_int("gc.rerereresolved", &cutoff_resolve);
 957        git_config_get_int("gc.rerereunresolved", &cutoff_noresolve);
 958        git_config(git_default_config, NULL);
 959        dir = opendir(git_path("rr-cache"));
 960        if (!dir)
 961                die_errno("unable to open rr-cache directory");
 962        /* Collect stale conflict IDs ... */
 963        while ((e = readdir(dir))) {
 964                if (is_dot_or_dotdot(e->d_name))
 965                        continue;
 966
 967                then = rerere_last_used_at(e->d_name);
 968                if (then) {
 969                        cutoff = cutoff_resolve;
 970                } else {
 971                        then = rerere_created_at(e->d_name);
 972                        if (!then)
 973                                continue;
 974                        cutoff = cutoff_noresolve;
 975                }
 976                if (then < now - cutoff * 86400)
 977                        string_list_append(&to_remove, e->d_name);
 978        }
 979        closedir(dir);
 980        /* ... and then remove them one-by-one */
 981        for (i = 0; i < to_remove.nr; i++)
 982                unlink_rr_item(dirname_to_id(to_remove.items[i].string));
 983        string_list_clear(&to_remove, 0);
 984        rollback_lock_file(&write_lock);
 985}
 986
 987/*
 988 * During a conflict resolution, after "rerere" recorded the
 989 * preimages, abandon them if the user did not resolve them or
 990 * record their resolutions.  And drop $GIT_DIR/MERGE_RR.
 991 *
 992 * NEEDSWORK: shouldn't we be calling this from "reset --hard"?
 993 */
 994void rerere_clear(struct string_list *merge_rr)
 995{
 996        int i;
 997
 998        if (setup_rerere(merge_rr, 0) < 0)
 999                return;
1000
1001        for (i = 0; i < merge_rr->nr; i++) {
1002                struct rerere_id *id = merge_rr->items[i].util;
1003                if (!has_rerere_resolution(id))
1004                        unlink_rr_item(id);
1005        }
1006        unlink_or_warn(git_path_merge_rr());
1007        rollback_lock_file(&write_lock);
1008}