rerere.con commit Merge branch 'mg/cherry-pick-multi-on-unborn' (db8128f)
   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#include "sha1-lookup.h"
  12
  13#define RESOLVED 0
  14#define PUNTED 1
  15#define THREE_STAGED 2
  16void *RERERE_RESOLVED = &RERERE_RESOLVED;
  17
  18/* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
  19static int rerere_enabled = -1;
  20
  21/* automatically update cleanly resolved paths to the index */
  22static int rerere_autoupdate;
  23
  24static int rerere_dir_nr;
  25static int rerere_dir_alloc;
  26
  27#define RR_HAS_POSTIMAGE 1
  28#define RR_HAS_PREIMAGE 2
  29static struct rerere_dir {
  30        unsigned char sha1[20];
  31        int status_alloc, status_nr;
  32        unsigned char *status;
  33} **rerere_dir;
  34
  35static void free_rerere_dirs(void)
  36{
  37        int i;
  38        for (i = 0; i < rerere_dir_nr; i++) {
  39                free(rerere_dir[i]->status);
  40                free(rerere_dir[i]);
  41        }
  42        free(rerere_dir);
  43        rerere_dir_nr = rerere_dir_alloc = 0;
  44        rerere_dir = NULL;
  45}
  46
  47static void free_rerere_id(struct string_list_item *item)
  48{
  49        free(item->util);
  50}
  51
  52static const char *rerere_id_hex(const struct rerere_id *id)
  53{
  54        return sha1_to_hex(id->collection->sha1);
  55}
  56
  57static void fit_variant(struct rerere_dir *rr_dir, int variant)
  58{
  59        variant++;
  60        ALLOC_GROW(rr_dir->status, variant, rr_dir->status_alloc);
  61        if (rr_dir->status_nr < variant) {
  62                memset(rr_dir->status + rr_dir->status_nr,
  63                       '\0', variant - rr_dir->status_nr);
  64                rr_dir->status_nr = variant;
  65        }
  66}
  67
  68static void assign_variant(struct rerere_id *id)
  69{
  70        int variant;
  71        struct rerere_dir *rr_dir = id->collection;
  72
  73        variant = id->variant;
  74        if (variant < 0) {
  75                for (variant = 0; variant < rr_dir->status_nr; variant++)
  76                        if (!rr_dir->status[variant])
  77                                break;
  78        }
  79        fit_variant(rr_dir, variant);
  80        id->variant = variant;
  81}
  82
  83const char *rerere_path(const struct rerere_id *id, const char *file)
  84{
  85        if (!file)
  86                return git_path("rr-cache/%s", rerere_id_hex(id));
  87
  88        if (id->variant <= 0)
  89                return git_path("rr-cache/%s/%s", rerere_id_hex(id), file);
  90
  91        return git_path("rr-cache/%s/%s.%d",
  92                        rerere_id_hex(id), file, id->variant);
  93}
  94
  95static int is_rr_file(const char *name, const char *filename, int *variant)
  96{
  97        const char *suffix;
  98        char *ep;
  99
 100        if (!strcmp(name, filename)) {
 101                *variant = 0;
 102                return 1;
 103        }
 104        if (!skip_prefix(name, filename, &suffix) || *suffix != '.')
 105                return 0;
 106
 107        errno = 0;
 108        *variant = strtol(suffix + 1, &ep, 10);
 109        if (errno || *ep)
 110                return 0;
 111        return 1;
 112}
 113
 114static void scan_rerere_dir(struct rerere_dir *rr_dir)
 115{
 116        struct dirent *de;
 117        DIR *dir = opendir(git_path("rr-cache/%s", sha1_to_hex(rr_dir->sha1)));
 118
 119        if (!dir)
 120                return;
 121        while ((de = readdir(dir)) != NULL) {
 122                int variant;
 123
 124                if (is_rr_file(de->d_name, "postimage", &variant)) {
 125                        fit_variant(rr_dir, variant);
 126                        rr_dir->status[variant] |= RR_HAS_POSTIMAGE;
 127                } else if (is_rr_file(de->d_name, "preimage", &variant)) {
 128                        fit_variant(rr_dir, variant);
 129                        rr_dir->status[variant] |= RR_HAS_PREIMAGE;
 130                }
 131        }
 132        closedir(dir);
 133}
 134
 135static const unsigned char *rerere_dir_sha1(size_t i, void *table)
 136{
 137        struct rerere_dir **rr_dir = table;
 138        return rr_dir[i]->sha1;
 139}
 140
 141static struct rerere_dir *find_rerere_dir(const char *hex)
 142{
 143        unsigned char sha1[20];
 144        struct rerere_dir *rr_dir;
 145        int pos;
 146
 147        if (get_sha1_hex(hex, sha1))
 148                return NULL; /* BUG */
 149        pos = sha1_pos(sha1, rerere_dir, rerere_dir_nr, rerere_dir_sha1);
 150        if (pos < 0) {
 151                rr_dir = xmalloc(sizeof(*rr_dir));
 152                hashcpy(rr_dir->sha1, sha1);
 153                rr_dir->status = NULL;
 154                rr_dir->status_nr = 0;
 155                rr_dir->status_alloc = 0;
 156                pos = -1 - pos;
 157
 158                /* Make sure the array is big enough ... */
 159                ALLOC_GROW(rerere_dir, rerere_dir_nr + 1, rerere_dir_alloc);
 160                /* ... and add it in. */
 161                rerere_dir_nr++;
 162                memmove(rerere_dir + pos + 1, rerere_dir + pos,
 163                        (rerere_dir_nr - pos - 1) * sizeof(*rerere_dir));
 164                rerere_dir[pos] = rr_dir;
 165                scan_rerere_dir(rr_dir);
 166        }
 167        return rerere_dir[pos];
 168}
 169
 170static int has_rerere_resolution(const struct rerere_id *id)
 171{
 172        const int both = RR_HAS_POSTIMAGE|RR_HAS_PREIMAGE;
 173        int variant = id->variant;
 174
 175        if (variant < 0)
 176                return 0;
 177        return ((id->collection->status[variant] & both) == both);
 178}
 179
 180static struct rerere_id *new_rerere_id_hex(char *hex)
 181{
 182        struct rerere_id *id = xmalloc(sizeof(*id));
 183        id->collection = find_rerere_dir(hex);
 184        id->variant = -1; /* not known yet */
 185        return id;
 186}
 187
 188static struct rerere_id *new_rerere_id(unsigned char *sha1)
 189{
 190        return new_rerere_id_hex(sha1_to_hex(sha1));
 191}
 192
 193/*
 194 * $GIT_DIR/MERGE_RR file is a collection of records, each of which is
 195 * "conflict ID", a HT and pathname, terminated with a NUL, and is
 196 * used to keep track of the set of paths that "rerere" may need to
 197 * work on (i.e. what is left by the previous invocation of "git
 198 * rerere" during the current conflict resolution session).
 199 */
 200static void read_rr(struct string_list *rr)
 201{
 202        struct strbuf buf = STRBUF_INIT;
 203        FILE *in = fopen(git_path_merge_rr(), "r");
 204
 205        if (!in)
 206                return;
 207        while (!strbuf_getwholeline(&buf, in, '\0')) {
 208                char *path;
 209                unsigned char sha1[20];
 210                struct rerere_id *id;
 211                int variant;
 212
 213                /* There has to be the hash, tab, path and then NUL */
 214                if (buf.len < 42 || get_sha1_hex(buf.buf, sha1))
 215                        die("corrupt MERGE_RR");
 216
 217                if (buf.buf[40] != '.') {
 218                        variant = 0;
 219                        path = buf.buf + 40;
 220                } else {
 221                        errno = 0;
 222                        variant = strtol(buf.buf + 41, &path, 10);
 223                        if (errno)
 224                                die("corrupt MERGE_RR");
 225                }
 226                if (*(path++) != '\t')
 227                        die("corrupt MERGE_RR");
 228                buf.buf[40] = '\0';
 229                id = new_rerere_id_hex(buf.buf);
 230                id->variant = variant;
 231                string_list_insert(rr, path)->util = id;
 232        }
 233        strbuf_release(&buf);
 234        fclose(in);
 235}
 236
 237static struct lock_file write_lock;
 238
 239static int write_rr(struct string_list *rr, int out_fd)
 240{
 241        int i;
 242        for (i = 0; i < rr->nr; i++) {
 243                struct strbuf buf = STRBUF_INIT;
 244                struct rerere_id *id;
 245
 246                assert(rr->items[i].util != RERERE_RESOLVED);
 247
 248                id = rr->items[i].util;
 249                if (!id)
 250                        continue;
 251                assert(id->variant >= 0);
 252                if (0 < id->variant)
 253                        strbuf_addf(&buf, "%s.%d\t%s%c",
 254                                    rerere_id_hex(id), id->variant,
 255                                    rr->items[i].string, 0);
 256                else
 257                        strbuf_addf(&buf, "%s\t%s%c",
 258                                    rerere_id_hex(id),
 259                                    rr->items[i].string, 0);
 260
 261                if (write_in_full(out_fd, buf.buf, buf.len) != buf.len)
 262                        die("unable to write rerere record");
 263
 264                strbuf_release(&buf);
 265        }
 266        if (commit_lock_file(&write_lock) != 0)
 267                die("unable to write rerere record");
 268        return 0;
 269}
 270
 271/*
 272 * "rerere" interacts with conflicted file contents using this I/O
 273 * abstraction.  It reads a conflicted contents from one place via
 274 * "getline()" method, and optionally can write it out after
 275 * normalizing the conflicted hunks to the "output".  Subclasses of
 276 * rerere_io embed this structure at the beginning of their own
 277 * rerere_io object.
 278 */
 279struct rerere_io {
 280        int (*getline)(struct strbuf *, struct rerere_io *);
 281        FILE *output;
 282        int wrerror;
 283        /* some more stuff */
 284};
 285
 286static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
 287{
 288        if (!count || *err)
 289                return;
 290        if (fwrite(p, count, 1, fp) != 1)
 291                *err = errno;
 292}
 293
 294static inline void ferr_puts(const char *s, FILE *fp, int *err)
 295{
 296        ferr_write(s, strlen(s), fp, err);
 297}
 298
 299static void rerere_io_putstr(const char *str, struct rerere_io *io)
 300{
 301        if (io->output)
 302                ferr_puts(str, io->output, &io->wrerror);
 303}
 304
 305/*
 306 * Write a conflict marker to io->output (if defined).
 307 */
 308static void rerere_io_putconflict(int ch, int size, struct rerere_io *io)
 309{
 310        char buf[64];
 311
 312        while (size) {
 313                if (size <= sizeof(buf) - 2) {
 314                        memset(buf, ch, size);
 315                        buf[size] = '\n';
 316                        buf[size + 1] = '\0';
 317                        size = 0;
 318                } else {
 319                        int sz = sizeof(buf) - 1;
 320
 321                        /*
 322                         * Make sure we will not write everything out
 323                         * in this round by leaving at least 1 byte
 324                         * for the next round, giving the next round
 325                         * a chance to add the terminating LF.  Yuck.
 326                         */
 327                        if (size <= sz)
 328                                sz -= (sz - size) + 1;
 329                        memset(buf, ch, sz);
 330                        buf[sz] = '\0';
 331                        size -= sz;
 332                }
 333                rerere_io_putstr(buf, io);
 334        }
 335}
 336
 337static void rerere_io_putmem(const char *mem, size_t sz, struct rerere_io *io)
 338{
 339        if (io->output)
 340                ferr_write(mem, sz, io->output, &io->wrerror);
 341}
 342
 343/*
 344 * Subclass of rerere_io that reads from an on-disk file
 345 */
 346struct rerere_io_file {
 347        struct rerere_io io;
 348        FILE *input;
 349};
 350
 351/*
 352 * ... and its getline() method implementation
 353 */
 354static int rerere_file_getline(struct strbuf *sb, struct rerere_io *io_)
 355{
 356        struct rerere_io_file *io = (struct rerere_io_file *)io_;
 357        return strbuf_getwholeline(sb, io->input, '\n');
 358}
 359
 360/*
 361 * Require the exact number of conflict marker letters, no more, no
 362 * less, followed by SP or any whitespace
 363 * (including LF).
 364 */
 365static int is_cmarker(char *buf, int marker_char, int marker_size)
 366{
 367        int want_sp;
 368
 369        /*
 370         * The beginning of our version and the end of their version
 371         * always are labeled like "<<<<< ours" or ">>>>> theirs",
 372         * hence we set want_sp for them.  Note that the version from
 373         * the common ancestor in diff3-style output is not always
 374         * labelled (e.g. "||||| common" is often seen but "|||||"
 375         * alone is also valid), so we do not set want_sp.
 376         */
 377        want_sp = (marker_char == '<') || (marker_char == '>');
 378
 379        while (marker_size--)
 380                if (*buf++ != marker_char)
 381                        return 0;
 382        if (want_sp && *buf != ' ')
 383                return 0;
 384        return isspace(*buf);
 385}
 386
 387/*
 388 * Read contents a file with conflicts, normalize the conflicts
 389 * by (1) discarding the common ancestor version in diff3-style,
 390 * (2) reordering our side and their side so that whichever sorts
 391 * alphabetically earlier comes before the other one, while
 392 * computing the "conflict ID", which is just an SHA-1 hash of
 393 * one side of the conflict, NUL, the other side of the conflict,
 394 * and NUL concatenated together.
 395 *
 396 * Return the number of conflict hunks found.
 397 *
 398 * NEEDSWORK: the logic and theory of operation behind this conflict
 399 * normalization may deserve to be documented somewhere, perhaps in
 400 * Documentation/technical/rerere.txt.
 401 */
 402static int handle_path(unsigned char *sha1, struct rerere_io *io, int marker_size)
 403{
 404        git_SHA_CTX ctx;
 405        int hunk_no = 0;
 406        enum {
 407                RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL
 408        } hunk = RR_CONTEXT;
 409        struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
 410        struct strbuf buf = STRBUF_INIT;
 411
 412        if (sha1)
 413                git_SHA1_Init(&ctx);
 414
 415        while (!io->getline(&buf, io)) {
 416                if (is_cmarker(buf.buf, '<', marker_size)) {
 417                        if (hunk != RR_CONTEXT)
 418                                goto bad;
 419                        hunk = RR_SIDE_1;
 420                } else if (is_cmarker(buf.buf, '|', marker_size)) {
 421                        if (hunk != RR_SIDE_1)
 422                                goto bad;
 423                        hunk = RR_ORIGINAL;
 424                } else if (is_cmarker(buf.buf, '=', marker_size)) {
 425                        if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
 426                                goto bad;
 427                        hunk = RR_SIDE_2;
 428                } else if (is_cmarker(buf.buf, '>', marker_size)) {
 429                        if (hunk != RR_SIDE_2)
 430                                goto bad;
 431                        if (strbuf_cmp(&one, &two) > 0)
 432                                strbuf_swap(&one, &two);
 433                        hunk_no++;
 434                        hunk = RR_CONTEXT;
 435                        rerere_io_putconflict('<', marker_size, io);
 436                        rerere_io_putmem(one.buf, one.len, io);
 437                        rerere_io_putconflict('=', marker_size, io);
 438                        rerere_io_putmem(two.buf, two.len, io);
 439                        rerere_io_putconflict('>', marker_size, io);
 440                        if (sha1) {
 441                                git_SHA1_Update(&ctx, one.buf ? one.buf : "",
 442                                            one.len + 1);
 443                                git_SHA1_Update(&ctx, two.buf ? two.buf : "",
 444                                            two.len + 1);
 445                        }
 446                        strbuf_reset(&one);
 447                        strbuf_reset(&two);
 448                } else if (hunk == RR_SIDE_1)
 449                        strbuf_addbuf(&one, &buf);
 450                else if (hunk == RR_ORIGINAL)
 451                        ; /* discard */
 452                else if (hunk == RR_SIDE_2)
 453                        strbuf_addbuf(&two, &buf);
 454                else
 455                        rerere_io_putstr(buf.buf, io);
 456                continue;
 457        bad:
 458                hunk = 99; /* force error exit */
 459                break;
 460        }
 461        strbuf_release(&one);
 462        strbuf_release(&two);
 463        strbuf_release(&buf);
 464
 465        if (sha1)
 466                git_SHA1_Final(sha1, &ctx);
 467        if (hunk != RR_CONTEXT)
 468                return -1;
 469        return hunk_no;
 470}
 471
 472/*
 473 * Scan the path for conflicts, do the "handle_path()" thing above, and
 474 * return the number of conflict hunks found.
 475 */
 476static int handle_file(const char *path, unsigned char *sha1, const char *output)
 477{
 478        int hunk_no = 0;
 479        struct rerere_io_file io;
 480        int marker_size = ll_merge_marker_size(path);
 481
 482        memset(&io, 0, sizeof(io));
 483        io.io.getline = rerere_file_getline;
 484        io.input = fopen(path, "r");
 485        io.io.wrerror = 0;
 486        if (!io.input)
 487                return error("Could not open %s", path);
 488
 489        if (output) {
 490                io.io.output = fopen(output, "w");
 491                if (!io.io.output) {
 492                        fclose(io.input);
 493                        return error("Could not write %s", output);
 494                }
 495        }
 496
 497        hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
 498
 499        fclose(io.input);
 500        if (io.io.wrerror)
 501                error("There were errors while writing %s (%s)",
 502                      path, strerror(io.io.wrerror));
 503        if (io.io.output && fclose(io.io.output))
 504                io.io.wrerror = error_errno("Failed to flush %s", path);
 505
 506        if (hunk_no < 0) {
 507                if (output)
 508                        unlink_or_warn(output);
 509                return error("Could not parse conflict hunks in %s", path);
 510        }
 511        if (io.io.wrerror)
 512                return -1;
 513        return hunk_no;
 514}
 515
 516/*
 517 * Look at a cache entry at "i" and see if it is not conflicting,
 518 * conflicting and we are willing to handle, or conflicting and
 519 * we are unable to handle, and return the determination in *type.
 520 * Return the cache index to be looked at next, by skipping the
 521 * stages we have already looked at in this invocation of this
 522 * function.
 523 */
 524static int check_one_conflict(int i, int *type)
 525{
 526        const struct cache_entry *e = active_cache[i];
 527
 528        if (!ce_stage(e)) {
 529                *type = RESOLVED;
 530                return i + 1;
 531        }
 532
 533        *type = PUNTED;
 534        while (ce_stage(active_cache[i]) == 1)
 535                i++;
 536
 537        /* Only handle regular files with both stages #2 and #3 */
 538        if (i + 1 < active_nr) {
 539                const struct cache_entry *e2 = active_cache[i];
 540                const struct cache_entry *e3 = active_cache[i + 1];
 541                if (ce_stage(e2) == 2 &&
 542                    ce_stage(e3) == 3 &&
 543                    ce_same_name(e, e3) &&
 544                    S_ISREG(e2->ce_mode) &&
 545                    S_ISREG(e3->ce_mode))
 546                        *type = THREE_STAGED;
 547        }
 548
 549        /* Skip the entries with the same name */
 550        while (i < active_nr && ce_same_name(e, active_cache[i]))
 551                i++;
 552        return i;
 553}
 554
 555/*
 556 * Scan the index and find paths that have conflicts that rerere can
 557 * handle, i.e. the ones that has both stages #2 and #3.
 558 *
 559 * NEEDSWORK: we do not record or replay a previous "resolve by
 560 * deletion" for a delete-modify conflict, as that is inherently risky
 561 * without knowing what modification is being discarded.  The only
 562 * safe case, i.e. both side doing the deletion and modification that
 563 * are identical to the previous round, might want to be handled,
 564 * though.
 565 */
 566static int find_conflict(struct string_list *conflict)
 567{
 568        int i;
 569        if (read_cache() < 0)
 570                return error("Could not read index");
 571
 572        for (i = 0; i < active_nr;) {
 573                int conflict_type;
 574                const struct cache_entry *e = active_cache[i];
 575                i = check_one_conflict(i, &conflict_type);
 576                if (conflict_type == THREE_STAGED)
 577                        string_list_insert(conflict, (const char *)e->name);
 578        }
 579        return 0;
 580}
 581
 582/*
 583 * The merge_rr list is meant to hold outstanding conflicted paths
 584 * that rerere could handle.  Abuse the list by adding other types of
 585 * entries to allow the caller to show "rerere remaining".
 586 *
 587 * - Conflicted paths that rerere does not handle are added
 588 * - Conflicted paths that have been resolved are marked as such
 589 *   by storing RERERE_RESOLVED to .util field (where conflict ID
 590 *   is expected to be stored).
 591 *
 592 * Do *not* write MERGE_RR file out after calling this function.
 593 *
 594 * NEEDSWORK: we may want to fix the caller that implements "rerere
 595 * remaining" to do this without abusing merge_rr.
 596 */
 597int rerere_remaining(struct string_list *merge_rr)
 598{
 599        int i;
 600        if (setup_rerere(merge_rr, RERERE_READONLY))
 601                return 0;
 602        if (read_cache() < 0)
 603                return error("Could not read index");
 604
 605        for (i = 0; i < active_nr;) {
 606                int conflict_type;
 607                const struct cache_entry *e = active_cache[i];
 608                i = check_one_conflict(i, &conflict_type);
 609                if (conflict_type == PUNTED)
 610                        string_list_insert(merge_rr, (const char *)e->name);
 611                else if (conflict_type == RESOLVED) {
 612                        struct string_list_item *it;
 613                        it = string_list_lookup(merge_rr, (const char *)e->name);
 614                        if (it != NULL) {
 615                                free_rerere_id(it);
 616                                it->util = RERERE_RESOLVED;
 617                        }
 618                }
 619        }
 620        return 0;
 621}
 622
 623/*
 624 * Try using the given conflict resolution "ID" to see
 625 * if that recorded conflict resolves cleanly what we
 626 * got in the "cur".
 627 */
 628static int try_merge(const struct rerere_id *id, const char *path,
 629                     mmfile_t *cur, mmbuffer_t *result)
 630{
 631        int ret;
 632        mmfile_t base = {NULL, 0}, other = {NULL, 0};
 633
 634        if (read_mmfile(&base, rerere_path(id, "preimage")) ||
 635            read_mmfile(&other, rerere_path(id, "postimage")))
 636                ret = 1;
 637        else
 638                /*
 639                 * A three-way merge. Note that this honors user-customizable
 640                 * low-level merge driver settings.
 641                 */
 642                ret = ll_merge(result, path, &base, NULL, cur, "", &other, "", NULL);
 643
 644        free(base.ptr);
 645        free(other.ptr);
 646
 647        return ret;
 648}
 649
 650/*
 651 * Find the conflict identified by "id"; the change between its
 652 * "preimage" (i.e. a previous contents with conflict markers) and its
 653 * "postimage" (i.e. the corresponding contents with conflicts
 654 * resolved) may apply cleanly to the contents stored in "path", i.e.
 655 * the conflict this time around.
 656 *
 657 * Returns 0 for successful replay of recorded resolution, or non-zero
 658 * for failure.
 659 */
 660static int merge(const struct rerere_id *id, const char *path)
 661{
 662        FILE *f;
 663        int ret;
 664        mmfile_t cur = {NULL, 0};
 665        mmbuffer_t result = {NULL, 0};
 666
 667        /*
 668         * Normalize the conflicts in path and write it out to
 669         * "thisimage" temporary file.
 670         */
 671        if ((handle_file(path, NULL, rerere_path(id, "thisimage")) < 0) ||
 672            read_mmfile(&cur, rerere_path(id, "thisimage"))) {
 673                ret = 1;
 674                goto out;
 675        }
 676
 677        ret = try_merge(id, path, &cur, &result);
 678        if (ret)
 679                goto out;
 680
 681        /*
 682         * A successful replay of recorded resolution.
 683         * Mark that "postimage" was used to help gc.
 684         */
 685        if (utime(rerere_path(id, "postimage"), NULL) < 0)
 686                warning_errno("failed utime() on %s",
 687                              rerere_path(id, "postimage"));
 688
 689        /* Update "path" with the resolution */
 690        f = fopen(path, "w");
 691        if (!f)
 692                return error_errno("Could not open %s", path);
 693        if (fwrite(result.ptr, result.size, 1, f) != 1)
 694                error_errno("Could not write %s", path);
 695        if (fclose(f))
 696                return error_errno("Writing %s failed", path);
 697
 698out:
 699        free(cur.ptr);
 700        free(result.ptr);
 701
 702        return ret;
 703}
 704
 705static struct lock_file index_lock;
 706
 707static void update_paths(struct string_list *update)
 708{
 709        int i;
 710
 711        hold_locked_index(&index_lock, 1);
 712
 713        for (i = 0; i < update->nr; i++) {
 714                struct string_list_item *item = &update->items[i];
 715                if (add_file_to_cache(item->string, 0))
 716                        exit(128);
 717                fprintf(stderr, "Staged '%s' using previous resolution.\n",
 718                        item->string);
 719        }
 720
 721        if (active_cache_changed) {
 722                if (write_locked_index(&the_index, &index_lock, COMMIT_LOCK))
 723                        die("Unable to write new index file");
 724        } else
 725                rollback_lock_file(&index_lock);
 726}
 727
 728static void remove_variant(struct rerere_id *id)
 729{
 730        unlink_or_warn(rerere_path(id, "postimage"));
 731        unlink_or_warn(rerere_path(id, "preimage"));
 732        id->collection->status[id->variant] = 0;
 733}
 734
 735/*
 736 * The path indicated by rr_item may still have conflict for which we
 737 * have a recorded resolution, in which case replay it and optionally
 738 * update it.  Or it may have been resolved by the user and we may
 739 * only have the preimage for that conflict, in which case the result
 740 * needs to be recorded as a resolution in a postimage file.
 741 */
 742static void do_rerere_one_path(struct string_list_item *rr_item,
 743                               struct string_list *update)
 744{
 745        const char *path = rr_item->string;
 746        struct rerere_id *id = rr_item->util;
 747        struct rerere_dir *rr_dir = id->collection;
 748        int variant;
 749
 750        variant = id->variant;
 751
 752        /* Has the user resolved it already? */
 753        if (variant >= 0) {
 754                if (!handle_file(path, NULL, NULL)) {
 755                        copy_file(rerere_path(id, "postimage"), path, 0666);
 756                        id->collection->status[variant] |= RR_HAS_POSTIMAGE;
 757                        fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 758                        free_rerere_id(rr_item);
 759                        rr_item->util = NULL;
 760                        return;
 761                }
 762                /*
 763                 * There may be other variants that can cleanly
 764                 * replay.  Try them and update the variant number for
 765                 * this one.
 766                 */
 767        }
 768
 769        /* Does any existing resolution apply cleanly? */
 770        for (variant = 0; variant < rr_dir->status_nr; variant++) {
 771                const int both = RR_HAS_PREIMAGE | RR_HAS_POSTIMAGE;
 772                struct rerere_id vid = *id;
 773
 774                if ((rr_dir->status[variant] & both) != both)
 775                        continue;
 776
 777                vid.variant = variant;
 778                if (merge(&vid, path))
 779                        continue; /* failed to replay */
 780
 781                /*
 782                 * If there already is a different variant that applies
 783                 * cleanly, there is no point maintaining our own variant.
 784                 */
 785                if (0 <= id->variant && id->variant != variant)
 786                        remove_variant(id);
 787
 788                if (rerere_autoupdate)
 789                        string_list_insert(update, path);
 790                else
 791                        fprintf(stderr,
 792                                "Resolved '%s' using previous resolution.\n",
 793                                path);
 794                free_rerere_id(rr_item);
 795                rr_item->util = NULL;
 796                return;
 797        }
 798
 799        /* None of the existing one applies; we need a new variant */
 800        assign_variant(id);
 801
 802        variant = id->variant;
 803        handle_file(path, NULL, rerere_path(id, "preimage"));
 804        if (id->collection->status[variant] & RR_HAS_POSTIMAGE) {
 805                const char *path = rerere_path(id, "postimage");
 806                if (unlink(path))
 807                        die_errno("cannot unlink stray '%s'", path);
 808                id->collection->status[variant] &= ~RR_HAS_POSTIMAGE;
 809        }
 810        id->collection->status[variant] |= RR_HAS_PREIMAGE;
 811        fprintf(stderr, "Recorded preimage for '%s'\n", path);
 812}
 813
 814static int do_plain_rerere(struct string_list *rr, int fd)
 815{
 816        struct string_list conflict = STRING_LIST_INIT_DUP;
 817        struct string_list update = STRING_LIST_INIT_DUP;
 818        int i;
 819
 820        find_conflict(&conflict);
 821
 822        /*
 823         * MERGE_RR records paths with conflicts immediately after
 824         * merge failed.  Some of the conflicted paths might have been
 825         * hand resolved in the working tree since then, but the
 826         * initial run would catch all and register their preimages.
 827         */
 828        for (i = 0; i < conflict.nr; i++) {
 829                struct rerere_id *id;
 830                unsigned char sha1[20];
 831                const char *path = conflict.items[i].string;
 832                int ret;
 833
 834                if (string_list_has_string(rr, path))
 835                        continue;
 836
 837                /*
 838                 * Ask handle_file() to scan and assign a
 839                 * conflict ID.  No need to write anything out
 840                 * yet.
 841                 */
 842                ret = handle_file(path, sha1, NULL);
 843                if (ret < 1)
 844                        continue;
 845
 846                id = new_rerere_id(sha1);
 847                string_list_insert(rr, path)->util = id;
 848
 849                /* Ensure that the directory exists. */
 850                mkdir_in_gitdir(rerere_path(id, NULL));
 851        }
 852
 853        for (i = 0; i < rr->nr; i++)
 854                do_rerere_one_path(&rr->items[i], &update);
 855
 856        if (update.nr)
 857                update_paths(&update);
 858
 859        return write_rr(rr, fd);
 860}
 861
 862static void git_rerere_config(void)
 863{
 864        git_config_get_bool("rerere.enabled", &rerere_enabled);
 865        git_config_get_bool("rerere.autoupdate", &rerere_autoupdate);
 866        git_config(git_default_config, NULL);
 867}
 868
 869static GIT_PATH_FUNC(git_path_rr_cache, "rr-cache")
 870
 871static int is_rerere_enabled(void)
 872{
 873        int rr_cache_exists;
 874
 875        if (!rerere_enabled)
 876                return 0;
 877
 878        rr_cache_exists = is_directory(git_path_rr_cache());
 879        if (rerere_enabled < 0)
 880                return rr_cache_exists;
 881
 882        if (!rr_cache_exists && mkdir_in_gitdir(git_path_rr_cache()))
 883                die("Could not create directory %s", git_path_rr_cache());
 884        return 1;
 885}
 886
 887int setup_rerere(struct string_list *merge_rr, int flags)
 888{
 889        int fd;
 890
 891        git_rerere_config();
 892        if (!is_rerere_enabled())
 893                return -1;
 894
 895        if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE))
 896                rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE);
 897        if (flags & RERERE_READONLY)
 898                fd = 0;
 899        else
 900                fd = hold_lock_file_for_update(&write_lock, git_path_merge_rr(),
 901                                               LOCK_DIE_ON_ERROR);
 902        read_rr(merge_rr);
 903        return fd;
 904}
 905
 906/*
 907 * The main entry point that is called internally from codepaths that
 908 * perform mergy operations, possibly leaving conflicted index entries
 909 * and working tree files.
 910 */
 911int rerere(int flags)
 912{
 913        struct string_list merge_rr = STRING_LIST_INIT_DUP;
 914        int fd, status;
 915
 916        fd = setup_rerere(&merge_rr, flags);
 917        if (fd < 0)
 918                return 0;
 919        status = do_plain_rerere(&merge_rr, fd);
 920        free_rerere_dirs();
 921        return status;
 922}
 923
 924/*
 925 * Subclass of rerere_io that reads from an in-core buffer that is a
 926 * strbuf
 927 */
 928struct rerere_io_mem {
 929        struct rerere_io io;
 930        struct strbuf input;
 931};
 932
 933/*
 934 * ... and its getline() method implementation
 935 */
 936static int rerere_mem_getline(struct strbuf *sb, struct rerere_io *io_)
 937{
 938        struct rerere_io_mem *io = (struct rerere_io_mem *)io_;
 939        char *ep;
 940        size_t len;
 941
 942        strbuf_release(sb);
 943        if (!io->input.len)
 944                return -1;
 945        ep = memchr(io->input.buf, '\n', io->input.len);
 946        if (!ep)
 947                ep = io->input.buf + io->input.len;
 948        else if (*ep == '\n')
 949                ep++;
 950        len = ep - io->input.buf;
 951        strbuf_add(sb, io->input.buf, len);
 952        strbuf_remove(&io->input, 0, len);
 953        return 0;
 954}
 955
 956static int handle_cache(const char *path, unsigned char *sha1, const char *output)
 957{
 958        mmfile_t mmfile[3] = {{NULL}};
 959        mmbuffer_t result = {NULL, 0};
 960        const struct cache_entry *ce;
 961        int pos, len, i, hunk_no;
 962        struct rerere_io_mem io;
 963        int marker_size = ll_merge_marker_size(path);
 964
 965        /*
 966         * Reproduce the conflicted merge in-core
 967         */
 968        len = strlen(path);
 969        pos = cache_name_pos(path, len);
 970        if (0 <= pos)
 971                return -1;
 972        pos = -pos - 1;
 973
 974        while (pos < active_nr) {
 975                enum object_type type;
 976                unsigned long size;
 977
 978                ce = active_cache[pos++];
 979                if (ce_namelen(ce) != len || memcmp(ce->name, path, len))
 980                        break;
 981                i = ce_stage(ce) - 1;
 982                if (!mmfile[i].ptr) {
 983                        mmfile[i].ptr = read_sha1_file(ce->sha1, &type, &size);
 984                        mmfile[i].size = size;
 985                }
 986        }
 987        for (i = 0; i < 3; i++)
 988                if (!mmfile[i].ptr && !mmfile[i].size)
 989                        mmfile[i].ptr = xstrdup("");
 990
 991        /*
 992         * NEEDSWORK: handle conflicts from merges with
 993         * merge.renormalize set, too?
 994         */
 995        ll_merge(&result, path, &mmfile[0], NULL,
 996                 &mmfile[1], "ours",
 997                 &mmfile[2], "theirs", NULL);
 998        for (i = 0; i < 3; i++)
 999                free(mmfile[i].ptr);
1000
1001        memset(&io, 0, sizeof(io));
1002        io.io.getline = rerere_mem_getline;
1003        if (output)
1004                io.io.output = fopen(output, "w");
1005        else
1006                io.io.output = NULL;
1007        strbuf_init(&io.input, 0);
1008        strbuf_attach(&io.input, result.ptr, result.size, result.size);
1009
1010        /*
1011         * Grab the conflict ID and optionally write the original
1012         * contents with conflict markers out.
1013         */
1014        hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
1015        strbuf_release(&io.input);
1016        if (io.io.output)
1017                fclose(io.io.output);
1018        return hunk_no;
1019}
1020
1021static int rerere_forget_one_path(const char *path, struct string_list *rr)
1022{
1023        const char *filename;
1024        struct rerere_id *id;
1025        unsigned char sha1[20];
1026        int ret;
1027        struct string_list_item *item;
1028
1029        /*
1030         * Recreate the original conflict from the stages in the
1031         * index and compute the conflict ID
1032         */
1033        ret = handle_cache(path, sha1, NULL);
1034        if (ret < 1)
1035                return error("Could not parse conflict hunks in '%s'", path);
1036
1037        /* Nuke the recorded resolution for the conflict */
1038        id = new_rerere_id(sha1);
1039
1040        for (id->variant = 0;
1041             id->variant < id->collection->status_nr;
1042             id->variant++) {
1043                mmfile_t cur = { NULL, 0 };
1044                mmbuffer_t result = {NULL, 0};
1045                int cleanly_resolved;
1046
1047                if (!has_rerere_resolution(id))
1048                        continue;
1049
1050                handle_cache(path, sha1, rerere_path(id, "thisimage"));
1051                if (read_mmfile(&cur, rerere_path(id, "thisimage"))) {
1052                        free(cur.ptr);
1053                        error("Failed to update conflicted state in '%s'", path);
1054                        goto fail_exit;
1055                }
1056                cleanly_resolved = !try_merge(id, path, &cur, &result);
1057                free(result.ptr);
1058                free(cur.ptr);
1059                if (cleanly_resolved)
1060                        break;
1061        }
1062
1063        if (id->collection->status_nr <= id->variant) {
1064                error("no remembered resolution for '%s'", path);
1065                goto fail_exit;
1066        }
1067
1068        filename = rerere_path(id, "postimage");
1069        if (unlink(filename)) {
1070                if (errno == ENOENT)
1071                        error("no remembered resolution for %s", path);
1072                else
1073                        error_errno("cannot unlink %s", filename);
1074                goto fail_exit;
1075        }
1076
1077        /*
1078         * Update the preimage so that the user can resolve the
1079         * conflict in the working tree, run us again to record
1080         * the postimage.
1081         */
1082        handle_cache(path, sha1, rerere_path(id, "preimage"));
1083        fprintf(stderr, "Updated preimage for '%s'\n", path);
1084
1085        /*
1086         * And remember that we can record resolution for this
1087         * conflict when the user is done.
1088         */
1089        item = string_list_insert(rr, path);
1090        free_rerere_id(item);
1091        item->util = id;
1092        fprintf(stderr, "Forgot resolution for %s\n", path);
1093        return 0;
1094
1095fail_exit:
1096        free(id);
1097        return -1;
1098}
1099
1100int rerere_forget(struct pathspec *pathspec)
1101{
1102        int i, fd;
1103        struct string_list conflict = STRING_LIST_INIT_DUP;
1104        struct string_list merge_rr = STRING_LIST_INIT_DUP;
1105
1106        if (read_cache() < 0)
1107                return error("Could not read index");
1108
1109        fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
1110        if (fd < 0)
1111                return 0;
1112
1113        /*
1114         * The paths may have been resolved (incorrectly);
1115         * recover the original conflicted state and then
1116         * find the conflicted paths.
1117         */
1118        unmerge_cache(pathspec);
1119        find_conflict(&conflict);
1120        for (i = 0; i < conflict.nr; i++) {
1121                struct string_list_item *it = &conflict.items[i];
1122                if (!match_pathspec(pathspec, it->string,
1123                                    strlen(it->string), 0, NULL, 0))
1124                        continue;
1125                rerere_forget_one_path(it->string, &merge_rr);
1126        }
1127        return write_rr(&merge_rr, fd);
1128}
1129
1130/*
1131 * Garbage collection support
1132 */
1133
1134static time_t rerere_created_at(struct rerere_id *id)
1135{
1136        struct stat st;
1137
1138        return stat(rerere_path(id, "preimage"), &st) ? (time_t) 0 : st.st_mtime;
1139}
1140
1141static time_t rerere_last_used_at(struct rerere_id *id)
1142{
1143        struct stat st;
1144
1145        return stat(rerere_path(id, "postimage"), &st) ? (time_t) 0 : st.st_mtime;
1146}
1147
1148/*
1149 * Remove the recorded resolution for a given conflict ID
1150 */
1151static void unlink_rr_item(struct rerere_id *id)
1152{
1153        unlink_or_warn(rerere_path(id, "thisimage"));
1154        remove_variant(id);
1155        id->collection->status[id->variant] = 0;
1156}
1157
1158static void prune_one(struct rerere_id *id, time_t now,
1159                      int cutoff_resolve, int cutoff_noresolve)
1160{
1161        time_t then;
1162        int cutoff;
1163
1164        then = rerere_last_used_at(id);
1165        if (then)
1166                cutoff = cutoff_resolve;
1167        else {
1168                then = rerere_created_at(id);
1169                if (!then)
1170                        return;
1171                cutoff = cutoff_noresolve;
1172        }
1173        if (then < now - cutoff * 86400)
1174                unlink_rr_item(id);
1175}
1176
1177void rerere_gc(struct string_list *rr)
1178{
1179        struct string_list to_remove = STRING_LIST_INIT_DUP;
1180        DIR *dir;
1181        struct dirent *e;
1182        int i;
1183        time_t now = time(NULL);
1184        int cutoff_noresolve = 15;
1185        int cutoff_resolve = 60;
1186
1187        if (setup_rerere(rr, 0) < 0)
1188                return;
1189
1190        git_config_get_int("gc.rerereresolved", &cutoff_resolve);
1191        git_config_get_int("gc.rerereunresolved", &cutoff_noresolve);
1192        git_config(git_default_config, NULL);
1193        dir = opendir(git_path("rr-cache"));
1194        if (!dir)
1195                die_errno("unable to open rr-cache directory");
1196        /* Collect stale conflict IDs ... */
1197        while ((e = readdir(dir))) {
1198                struct rerere_dir *rr_dir;
1199                struct rerere_id id;
1200                int now_empty;
1201
1202                if (is_dot_or_dotdot(e->d_name))
1203                        continue;
1204                rr_dir = find_rerere_dir(e->d_name);
1205                if (!rr_dir)
1206                        continue; /* or should we remove e->d_name? */
1207
1208                now_empty = 1;
1209                for (id.variant = 0, id.collection = rr_dir;
1210                     id.variant < id.collection->status_nr;
1211                     id.variant++) {
1212                        prune_one(&id, now, cutoff_resolve, cutoff_noresolve);
1213                        if (id.collection->status[id.variant])
1214                                now_empty = 0;
1215                }
1216                if (now_empty)
1217                        string_list_append(&to_remove, e->d_name);
1218        }
1219        closedir(dir);
1220
1221        /* ... and then remove the empty directories */
1222        for (i = 0; i < to_remove.nr; i++)
1223                rmdir(git_path("rr-cache/%s", to_remove.items[i].string));
1224        string_list_clear(&to_remove, 0);
1225        rollback_lock_file(&write_lock);
1226}
1227
1228/*
1229 * During a conflict resolution, after "rerere" recorded the
1230 * preimages, abandon them if the user did not resolve them or
1231 * record their resolutions.  And drop $GIT_DIR/MERGE_RR.
1232 *
1233 * NEEDSWORK: shouldn't we be calling this from "reset --hard"?
1234 */
1235void rerere_clear(struct string_list *merge_rr)
1236{
1237        int i;
1238
1239        if (setup_rerere(merge_rr, 0) < 0)
1240                return;
1241
1242        for (i = 0; i < merge_rr->nr; i++) {
1243                struct rerere_id *id = merge_rr->items[i].util;
1244                if (!has_rerere_resolution(id)) {
1245                        unlink_rr_item(id);
1246                        rmdir(rerere_path(id, NULL));
1247                }
1248        }
1249        unlink_or_warn(git_path_merge_rr());
1250        rollback_lock_file(&write_lock);
1251}