Andrew's git / gitweb.git / rerere.c
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rerere.con commit Documentation/merge subtree How-To: fix typo (59ab4eb)
   1#include "cache.h"
   2#include "string-list.h"
   3#include "rerere.h"
   4#include "xdiff-interface.h"
   5#include "dir.h"
   6#include "resolve-undo.h"
   7#include "ll-merge.h"
   8#include "attr.h"
   9
  10/* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
  11static int rerere_enabled = -1;
  12
  13/* automatically update cleanly resolved paths to the index */
  14static int rerere_autoupdate;
  15
  16static char *merge_rr_path;
  17
  18const char *rerere_path(const char *hex, const char *file)
  19{
  20        return git_path("rr-cache/%s/%s", hex, file);
  21}
  22
  23int has_rerere_resolution(const char *hex)
  24{
  25        struct stat st;
  26        return !stat(rerere_path(hex, "postimage"), &st);
  27}
  28
  29static void read_rr(struct string_list *rr)
  30{
  31        unsigned char sha1[20];
  32        char buf[PATH_MAX];
  33        FILE *in = fopen(merge_rr_path, "r");
  34        if (!in)
  35                return;
  36        while (fread(buf, 40, 1, in) == 1) {
  37                int i;
  38                char *name;
  39                if (get_sha1_hex(buf, sha1))
  40                        die("corrupt MERGE_RR");
  41                buf[40] = '\0';
  42                name = xstrdup(buf);
  43                if (fgetc(in) != '\t')
  44                        die("corrupt MERGE_RR");
  45                for (i = 0; i < sizeof(buf) && (buf[i] = fgetc(in)); i++)
  46                        ; /* do nothing */
  47                if (i == sizeof(buf))
  48                        die("filename too long");
  49                string_list_insert(rr, buf)->util = name;
  50        }
  51        fclose(in);
  52}
  53
  54static struct lock_file write_lock;
  55
  56static int write_rr(struct string_list *rr, int out_fd)
  57{
  58        int i;
  59        for (i = 0; i < rr->nr; i++) {
  60                const char *path;
  61                int length;
  62                if (!rr->items[i].util)
  63                        continue;
  64                path = rr->items[i].string;
  65                length = strlen(path) + 1;
  66                if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
  67                    write_str_in_full(out_fd, "\t") != 1 ||
  68                    write_in_full(out_fd, path, length) != length)
  69                        die("unable to write rerere record");
  70        }
  71        if (commit_lock_file(&write_lock) != 0)
  72                die("unable to write rerere record");
  73        return 0;
  74}
  75
  76static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
  77{
  78        if (!count || *err)
  79                return;
  80        if (fwrite(p, count, 1, fp) != 1)
  81                *err = errno;
  82}
  83
  84static inline void ferr_puts(const char *s, FILE *fp, int *err)
  85{
  86        ferr_write(s, strlen(s), fp, err);
  87}
  88
  89struct rerere_io {
  90        int (*getline)(struct strbuf *, struct rerere_io *);
  91        FILE *output;
  92        int wrerror;
  93        /* some more stuff */
  94};
  95
  96static void rerere_io_putstr(const char *str, struct rerere_io *io)
  97{
  98        if (io->output)
  99                ferr_puts(str, io->output, &io->wrerror);
 100}
 101
 102static void rerere_io_putconflict(int ch, int size, struct rerere_io *io)
 103{
 104        char buf[64];
 105
 106        while (size) {
 107                if (size < sizeof(buf) - 2) {
 108                        memset(buf, ch, size);
 109                        buf[size] = '\n';
 110                        buf[size + 1] = '\0';
 111                        size = 0;
 112                } else {
 113                        int sz = sizeof(buf) - 1;
 114                        if (size <= sz)
 115                                sz -= (sz - size) + 1;
 116                        memset(buf, ch, sz);
 117                        buf[sz] = '\0';
 118                        size -= sz;
 119                }
 120                rerere_io_putstr(buf, io);
 121        }
 122}
 123
 124static void rerere_io_putmem(const char *mem, size_t sz, struct rerere_io *io)
 125{
 126        if (io->output)
 127                ferr_write(mem, sz, io->output, &io->wrerror);
 128}
 129
 130struct rerere_io_file {
 131        struct rerere_io io;
 132        FILE *input;
 133};
 134
 135static int rerere_file_getline(struct strbuf *sb, struct rerere_io *io_)
 136{
 137        struct rerere_io_file *io = (struct rerere_io_file *)io_;
 138        return strbuf_getwholeline(sb, io->input, '\n');
 139}
 140
 141static int is_cmarker(char *buf, int marker_char, int marker_size, int want_sp)
 142{
 143        while (marker_size--)
 144                if (*buf++ != marker_char)
 145                        return 0;
 146        if (want_sp && *buf != ' ')
 147                return 0;
 148        return isspace(*buf);
 149}
 150
 151static int handle_path(unsigned char *sha1, struct rerere_io *io, int marker_size)
 152{
 153        git_SHA_CTX ctx;
 154        int hunk_no = 0;
 155        enum {
 156                RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL
 157        } hunk = RR_CONTEXT;
 158        struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
 159        struct strbuf buf = STRBUF_INIT;
 160
 161        if (sha1)
 162                git_SHA1_Init(&ctx);
 163
 164        while (!io->getline(&buf, io)) {
 165                if (is_cmarker(buf.buf, '<', marker_size, 1)) {
 166                        if (hunk != RR_CONTEXT)
 167                                goto bad;
 168                        hunk = RR_SIDE_1;
 169                } else if (is_cmarker(buf.buf, '|', marker_size, 0)) {
 170                        if (hunk != RR_SIDE_1)
 171                                goto bad;
 172                        hunk = RR_ORIGINAL;
 173                } else if (is_cmarker(buf.buf, '=', marker_size, 0)) {
 174                        if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
 175                                goto bad;
 176                        hunk = RR_SIDE_2;
 177                } else if (is_cmarker(buf.buf, '>', marker_size, 1)) {
 178                        if (hunk != RR_SIDE_2)
 179                                goto bad;
 180                        if (strbuf_cmp(&one, &two) > 0)
 181                                strbuf_swap(&one, &two);
 182                        hunk_no++;
 183                        hunk = RR_CONTEXT;
 184                        rerere_io_putconflict('<', marker_size, io);
 185                        rerere_io_putmem(one.buf, one.len, io);
 186                        rerere_io_putconflict('=', marker_size, io);
 187                        rerere_io_putmem(two.buf, two.len, io);
 188                        rerere_io_putconflict('>', marker_size, io);
 189                        if (sha1) {
 190                                git_SHA1_Update(&ctx, one.buf ? one.buf : "",
 191                                            one.len + 1);
 192                                git_SHA1_Update(&ctx, two.buf ? two.buf : "",
 193                                            two.len + 1);
 194                        }
 195                        strbuf_reset(&one);
 196                        strbuf_reset(&two);
 197                } else if (hunk == RR_SIDE_1)
 198                        strbuf_addstr(&one, buf.buf);
 199                else if (hunk == RR_ORIGINAL)
 200                        ; /* discard */
 201                else if (hunk == RR_SIDE_2)
 202                        strbuf_addstr(&two, buf.buf);
 203                else
 204                        rerere_io_putstr(buf.buf, io);
 205                continue;
 206        bad:
 207                hunk = 99; /* force error exit */
 208                break;
 209        }
 210        strbuf_release(&one);
 211        strbuf_release(&two);
 212        strbuf_release(&buf);
 213
 214        if (sha1)
 215                git_SHA1_Final(sha1, &ctx);
 216        if (hunk != RR_CONTEXT)
 217                return -1;
 218        return hunk_no;
 219}
 220
 221static int handle_file(const char *path, unsigned char *sha1, const char *output)
 222{
 223        int hunk_no = 0;
 224        struct rerere_io_file io;
 225        int marker_size = ll_merge_marker_size(path);
 226
 227        memset(&io, 0, sizeof(io));
 228        io.io.getline = rerere_file_getline;
 229        io.input = fopen(path, "r");
 230        io.io.wrerror = 0;
 231        if (!io.input)
 232                return error("Could not open %s", path);
 233
 234        if (output) {
 235                io.io.output = fopen(output, "w");
 236                if (!io.io.output) {
 237                        fclose(io.input);
 238                        return error("Could not write %s", output);
 239                }
 240        }
 241
 242        hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
 243
 244        fclose(io.input);
 245        if (io.io.wrerror)
 246                error("There were errors while writing %s (%s)",
 247                      path, strerror(io.io.wrerror));
 248        if (io.io.output && fclose(io.io.output))
 249                io.io.wrerror = error("Failed to flush %s: %s",
 250                                      path, strerror(errno));
 251
 252        if (hunk_no < 0) {
 253                if (output)
 254                        unlink_or_warn(output);
 255                return error("Could not parse conflict hunks in %s", path);
 256        }
 257        if (io.io.wrerror)
 258                return -1;
 259        return hunk_no;
 260}
 261
 262struct rerere_io_mem {
 263        struct rerere_io io;
 264        struct strbuf input;
 265};
 266
 267static int rerere_mem_getline(struct strbuf *sb, struct rerere_io *io_)
 268{
 269        struct rerere_io_mem *io = (struct rerere_io_mem *)io_;
 270        char *ep;
 271        size_t len;
 272
 273        strbuf_release(sb);
 274        if (!io->input.len)
 275                return -1;
 276        ep = strchrnul(io->input.buf, '\n');
 277        if (*ep == '\n')
 278                ep++;
 279        len = ep - io->input.buf;
 280        strbuf_add(sb, io->input.buf, len);
 281        strbuf_remove(&io->input, 0, len);
 282        return 0;
 283}
 284
 285static int handle_cache(const char *path, unsigned char *sha1, const char *output)
 286{
 287        mmfile_t mmfile[3];
 288        mmbuffer_t result = {NULL, 0};
 289        struct cache_entry *ce;
 290        int pos, len, i, hunk_no;
 291        struct rerere_io_mem io;
 292        int marker_size = ll_merge_marker_size(path);
 293
 294        /*
 295         * Reproduce the conflicted merge in-core
 296         */
 297        len = strlen(path);
 298        pos = cache_name_pos(path, len);
 299        if (0 <= pos)
 300                return -1;
 301        pos = -pos - 1;
 302
 303        for (i = 0; i < 3; i++) {
 304                enum object_type type;
 305                unsigned long size;
 306
 307                mmfile[i].size = 0;
 308                mmfile[i].ptr = NULL;
 309                if (active_nr <= pos)
 310                        break;
 311                ce = active_cache[pos++];
 312                if (ce_namelen(ce) != len || memcmp(ce->name, path, len)
 313                    || ce_stage(ce) != i + 1)
 314                        break;
 315                mmfile[i].ptr = read_sha1_file(ce->sha1, &type, &size);
 316                mmfile[i].size = size;
 317        }
 318        for (i = 0; i < 3; i++) {
 319                if (!mmfile[i].ptr && !mmfile[i].size)
 320                        mmfile[i].ptr = xstrdup("");
 321        }
 322        /*
 323         * NEEDSWORK: handle conflicts from merges with
 324         * merge.renormalize set, too
 325         */
 326        ll_merge(&result, path, &mmfile[0], NULL,
 327                 &mmfile[1], "ours",
 328                 &mmfile[2], "theirs", NULL);
 329        for (i = 0; i < 3; i++)
 330                free(mmfile[i].ptr);
 331
 332        memset(&io, 0, sizeof(io));
 333        io.io.getline = rerere_mem_getline;
 334        if (output)
 335                io.io.output = fopen(output, "w");
 336        else
 337                io.io.output = NULL;
 338        strbuf_init(&io.input, 0);
 339        strbuf_attach(&io.input, result.ptr, result.size, result.size);
 340
 341        hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
 342        strbuf_release(&io.input);
 343        if (io.io.output)
 344                fclose(io.io.output);
 345        return hunk_no;
 346}
 347
 348static int find_conflict(struct string_list *conflict)
 349{
 350        int i;
 351        if (read_cache() < 0)
 352                return error("Could not read index");
 353        for (i = 0; i+1 < active_nr; i++) {
 354                struct cache_entry *e2 = active_cache[i];
 355                struct cache_entry *e3 = active_cache[i+1];
 356                if (ce_stage(e2) == 2 &&
 357                    ce_stage(e3) == 3 &&
 358                    ce_same_name(e2, e3) &&
 359                    S_ISREG(e2->ce_mode) &&
 360                    S_ISREG(e3->ce_mode)) {
 361                        string_list_insert(conflict, (const char *)e2->name);
 362                        i++; /* skip over both #2 and #3 */
 363                }
 364        }
 365        return 0;
 366}
 367
 368static int merge(const char *name, const char *path)
 369{
 370        int ret;
 371        mmfile_t cur = {NULL, 0}, base = {NULL, 0}, other = {NULL, 0};
 372        mmbuffer_t result = {NULL, 0};
 373
 374        if (handle_file(path, NULL, rerere_path(name, "thisimage")) < 0)
 375                return 1;
 376
 377        if (read_mmfile(&cur, rerere_path(name, "thisimage")) ||
 378                        read_mmfile(&base, rerere_path(name, "preimage")) ||
 379                        read_mmfile(&other, rerere_path(name, "postimage"))) {
 380                ret = 1;
 381                goto out;
 382        }
 383        ret = ll_merge(&result, path, &base, NULL, &cur, "", &other, "", 0);
 384        if (!ret) {
 385                FILE *f;
 386
 387                if (utime(rerere_path(name, "postimage"), NULL) < 0)
 388                        warning("failed utime() on %s: %s",
 389                                        rerere_path(name, "postimage"),
 390                                        strerror(errno));
 391                f = fopen(path, "w");
 392                if (!f)
 393                        return error("Could not open %s: %s", path,
 394                                     strerror(errno));
 395                if (fwrite(result.ptr, result.size, 1, f) != 1)
 396                        error("Could not write %s: %s", path, strerror(errno));
 397                if (fclose(f))
 398                        return error("Writing %s failed: %s", path,
 399                                     strerror(errno));
 400        }
 401
 402out:
 403        free(cur.ptr);
 404        free(base.ptr);
 405        free(other.ptr);
 406        free(result.ptr);
 407
 408        return ret;
 409}
 410
 411static struct lock_file index_lock;
 412
 413static int update_paths(struct string_list *update)
 414{
 415        int i;
 416        int fd = hold_locked_index(&index_lock, 0);
 417        int status = 0;
 418
 419        if (fd < 0)
 420                return -1;
 421
 422        for (i = 0; i < update->nr; i++) {
 423                struct string_list_item *item = &update->items[i];
 424                if (add_file_to_cache(item->string, ADD_CACHE_IGNORE_ERRORS))
 425                        status = -1;
 426        }
 427
 428        if (!status && active_cache_changed) {
 429                if (write_cache(fd, active_cache, active_nr) ||
 430                    commit_locked_index(&index_lock))
 431                        die("Unable to write new index file");
 432        } else if (fd >= 0)
 433                rollback_lock_file(&index_lock);
 434        return status;
 435}
 436
 437static int do_plain_rerere(struct string_list *rr, int fd)
 438{
 439        struct string_list conflict = STRING_LIST_INIT_DUP;
 440        struct string_list update = STRING_LIST_INIT_DUP;
 441        int i;
 442
 443        find_conflict(&conflict);
 444
 445        /*
 446         * MERGE_RR records paths with conflicts immediately after merge
 447         * failed.  Some of the conflicted paths might have been hand resolved
 448         * in the working tree since then, but the initial run would catch all
 449         * and register their preimages.
 450         */
 451
 452        for (i = 0; i < conflict.nr; i++) {
 453                const char *path = conflict.items[i].string;
 454                if (!string_list_has_string(rr, path)) {
 455                        unsigned char sha1[20];
 456                        char *hex;
 457                        int ret;
 458                        ret = handle_file(path, sha1, NULL);
 459                        if (ret < 1)
 460                                continue;
 461                        hex = xstrdup(sha1_to_hex(sha1));
 462                        string_list_insert(rr, path)->util = hex;
 463                        if (mkdir(git_path("rr-cache/%s", hex), 0755))
 464                                continue;
 465                        handle_file(path, NULL, rerere_path(hex, "preimage"));
 466                        fprintf(stderr, "Recorded preimage for '%s'\n", path);
 467                }
 468        }
 469
 470        /*
 471         * Now some of the paths that had conflicts earlier might have been
 472         * hand resolved.  Others may be similar to a conflict already that
 473         * was resolved before.
 474         */
 475
 476        for (i = 0; i < rr->nr; i++) {
 477                int ret;
 478                const char *path = rr->items[i].string;
 479                const char *name = (const char *)rr->items[i].util;
 480
 481                if (has_rerere_resolution(name)) {
 482                        if (!merge(name, path)) {
 483                                if (rerere_autoupdate)
 484                                        string_list_insert(&update, path);
 485                                fprintf(stderr,
 486                                        "%s '%s' using previous resolution.\n",
 487                                        rerere_autoupdate
 488                                        ? "Staged" : "Resolved",
 489                                        path);
 490                                goto mark_resolved;
 491                        }
 492                }
 493
 494                /* Let's see if we have resolved it. */
 495                ret = handle_file(path, NULL, NULL);
 496                if (ret)
 497                        continue;
 498
 499                fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 500                copy_file(rerere_path(name, "postimage"), path, 0666);
 501        mark_resolved:
 502                rr->items[i].util = NULL;
 503        }
 504
 505        if (update.nr)
 506                update_paths(&update);
 507
 508        return write_rr(rr, fd);
 509}
 510
 511static int git_rerere_config(const char *var, const char *value, void *cb)
 512{
 513        if (!strcmp(var, "rerere.enabled"))
 514                rerere_enabled = git_config_bool(var, value);
 515        else if (!strcmp(var, "rerere.autoupdate"))
 516                rerere_autoupdate = git_config_bool(var, value);
 517        else
 518                return git_default_config(var, value, cb);
 519        return 0;
 520}
 521
 522static int is_rerere_enabled(void)
 523{
 524        const char *rr_cache;
 525        int rr_cache_exists;
 526
 527        if (!rerere_enabled)
 528                return 0;
 529
 530        rr_cache = git_path("rr-cache");
 531        rr_cache_exists = is_directory(rr_cache);
 532        if (rerere_enabled < 0)
 533                return rr_cache_exists;
 534
 535        if (!rr_cache_exists &&
 536            (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 537                die("Could not create directory %s", rr_cache);
 538        return 1;
 539}
 540
 541int setup_rerere(struct string_list *merge_rr, int flags)
 542{
 543        int fd;
 544
 545        git_config(git_rerere_config, NULL);
 546        if (!is_rerere_enabled())
 547                return -1;
 548
 549        if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE))
 550                rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE);
 551        merge_rr_path = git_pathdup("MERGE_RR");
 552        fd = hold_lock_file_for_update(&write_lock, merge_rr_path,
 553                                       LOCK_DIE_ON_ERROR);
 554        read_rr(merge_rr);
 555        return fd;
 556}
 557
 558int rerere(int flags)
 559{
 560        struct string_list merge_rr = STRING_LIST_INIT_DUP;
 561        int fd;
 562
 563        fd = setup_rerere(&merge_rr, flags);
 564        if (fd < 0)
 565                return 0;
 566        return do_plain_rerere(&merge_rr, fd);
 567}
 568
 569static int rerere_forget_one_path(const char *path, struct string_list *rr)
 570{
 571        const char *filename;
 572        char *hex;
 573        unsigned char sha1[20];
 574        int ret;
 575
 576        ret = handle_cache(path, sha1, NULL);
 577        if (ret < 1)
 578                return error("Could not parse conflict hunks in '%s'", path);
 579        hex = xstrdup(sha1_to_hex(sha1));
 580        filename = rerere_path(hex, "postimage");
 581        if (unlink(filename))
 582                return (errno == ENOENT
 583                        ? error("no remembered resolution for %s", path)
 584                        : error("cannot unlink %s: %s", filename, strerror(errno)));
 585
 586        handle_cache(path, sha1, rerere_path(hex, "preimage"));
 587        fprintf(stderr, "Updated preimage for '%s'\n", path);
 588
 589
 590        string_list_insert(rr, path)->util = hex;
 591        fprintf(stderr, "Forgot resolution for %s\n", path);
 592        return 0;
 593}
 594
 595int rerere_forget(const char **pathspec)
 596{
 597        int i, fd;
 598        struct string_list conflict = STRING_LIST_INIT_DUP;
 599        struct string_list merge_rr = STRING_LIST_INIT_DUP;
 600
 601        if (read_cache() < 0)
 602                return error("Could not read index");
 603
 604        fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
 605
 606        unmerge_cache(pathspec);
 607        find_conflict(&conflict);
 608        for (i = 0; i < conflict.nr; i++) {
 609                struct string_list_item *it = &conflict.items[i];
 610                if (!match_pathspec(pathspec, it->string, strlen(it->string),
 611                                    0, NULL))
 612                        continue;
 613                rerere_forget_one_path(it->string, &merge_rr);
 614        }
 615        return write_rr(&merge_rr, fd);
 616}