rerere.c

   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 #define RESOLVED 0
  11 #define PUNTED 1
  12 #define THREE_STAGED 2
  13 void *RERERE_RESOLVED = &RERERE_RESOLVED;
  14
  15 /* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
  16 static int rerere_enabled = -1;
  17
  18 /* automatically update cleanly resolved paths to the index */
  19 static int rerere_autoupdate;
  20
  21 static char *merge_rr_path;
  22
  23 const char *rerere_path(const char *hex, const char *file)
  24 {
  25         return git_path("rr-cache/%s/%s", hex, file);
  26 }
  27
  28 int has_rerere_resolution(const char *hex)
  29 {
  30         struct stat st;
  31         return !stat(rerere_path(hex, "postimage"), &st);
  32 }
  33
  34 static void read_rr(struct string_list *rr)
  35 {
  36         unsigned char sha1[20];
  37         char buf[PATH_MAX];
  38         FILE *in = fopen(merge_rr_path, "r");
  39         if (!in)
  40                 return;
  41         while (fread(buf, 40, 1, in) == 1) {
  42                 int i;
  43                 char *name;
  44                 if (get_sha1_hex(buf, sha1))
  45                         die("corrupt MERGE_RR");
  46                 buf[40] = '\0';
  47                 name = xstrdup(buf);
  48                 if (fgetc(in) != '\t')
  49                         die("corrupt MERGE_RR");
  50                 for (i = 0; i < sizeof(buf) && (buf[i] = fgetc(in)); i++)
  51                         ; /* do nothing */
  52                 if (i == sizeof(buf))
  53                         die("filename too long");
  54                 string_list_insert(rr, buf)->util = name;
  55         }
  56         fclose(in);
  57 }
  58
  59 static struct lock_file write_lock;
  60
  61 static int write_rr(struct string_list *rr, int out_fd)
  62 {
  63         int i;
  64         for (i = 0; i < rr->nr; i++) {
  65                 const char *path;
  66                 int length;
  67                 if (!rr->items[i].util)
  68                         continue;
  69                 path = rr->items[i].string;
  70                 length = strlen(path) + 1;
  71                 if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
  72                     write_str_in_full(out_fd, "\t") != 1 ||
  73                     write_in_full(out_fd, path, length) != length)
  74                         die("unable to write rerere record");
  75         }
  76         if (commit_lock_file(&write_lock) != 0)
  77                 die("unable to write rerere record");
  78         return 0;
  79 }
  80
  81 static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
  82 {
  83         if (!count || *err)
  84                 return;
  85         if (fwrite(p, count, 1, fp) != 1)
  86                 *err = errno;
  87 }
  88
  89 static inline void ferr_puts(const char *s, FILE *fp, int *err)
  90 {
  91         ferr_write(s, strlen(s), fp, err);
  92 }
  93
  94 struct rerere_io {
  95         int (*getline)(struct strbuf *, struct rerere_io *);
  96         FILE *output;
  97         int wrerror;
  98         /* some more stuff */
  99 };
 100
 101 static void rerere_io_putstr(const char *str, struct rerere_io *io)
 102 {
 103         if (io->output)
 104                 ferr_puts(str, io->output, &io->wrerror);
 105 }
 106
 107 static void rerere_io_putconflict(int ch, int size, struct rerere_io *io)
 108 {
 109         char buf[64];
 110
 111         while (size) {
 112                 if (size < sizeof(buf) - 2) {
 113                         memset(buf, ch, size);
 114                         buf[size] = '\n';
 115                         buf[size + 1] = '\0';
 116                         size = 0;
 117                 } else {
 118                         int sz = sizeof(buf) - 1;
 119                         if (size <= sz)
 120                                 sz -= (sz - size) + 1;
 121                         memset(buf, ch, sz);
 122                         buf[sz] = '\0';
 123                         size -= sz;
 124                 }
 125                 rerere_io_putstr(buf, io);
 126         }
 127 }
 128
 129 static void rerere_io_putmem(const char *mem, size_t sz, struct rerere_io *io)
 130 {
 131         if (io->output)
 132                 ferr_write(mem, sz, io->output, &io->wrerror);
 133 }
 134
 135 struct rerere_io_file {
 136         struct rerere_io io;
 137         FILE *input;
 138 };
 139
 140 static int rerere_file_getline(struct strbuf *sb, struct rerere_io *io_)
 141 {
 142         struct rerere_io_file *io = (struct rerere_io_file *)io_;
 143         return strbuf_getwholeline(sb, io->input, '\n');
 144 }
 145
 146 static int is_cmarker(char *buf, int marker_char, int marker_size, int want_sp)
 147 {
 148         while (marker_size--)
 149                 if (*buf++ != marker_char)
 150                         return 0;
 151         if (want_sp && *buf != ' ')
 152                 return 0;
 153         return isspace(*buf);
 154 }
 155
 156 static int handle_path(unsigned char *sha1, struct rerere_io *io, int marker_size)
 157 {
 158         git_SHA_CTX ctx;
 159         int hunk_no = 0;
 160         enum {
 161                 RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL
 162         } hunk = RR_CONTEXT;
 163         struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
 164         struct strbuf buf = STRBUF_INIT;
 165
 166         if (sha1)
 167                 git_SHA1_Init(&ctx);
 168
 169         while (!io->getline(&buf, io)) {
 170                 if (is_cmarker(buf.buf, '<', marker_size, 1)) {
 171                         if (hunk != RR_CONTEXT)
 172                                 goto bad;
 173                         hunk = RR_SIDE_1;
 174                 } else if (is_cmarker(buf.buf, '|', marker_size, 0)) {
 175                         if (hunk != RR_SIDE_1)
 176                                 goto bad;
 177                         hunk = RR_ORIGINAL;
 178                 } else if (is_cmarker(buf.buf, '=', marker_size, 0)) {
 179                         if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
 180                                 goto bad;
 181                         hunk = RR_SIDE_2;
 182                 } else if (is_cmarker(buf.buf, '>', marker_size, 1)) {
 183                         if (hunk != RR_SIDE_2)
 184                                 goto bad;
 185                         if (strbuf_cmp(&one, &two) > 0)
 186                                 strbuf_swap(&one, &two);
 187                         hunk_no++;
 188                         hunk = RR_CONTEXT;
 189                         rerere_io_putconflict('<', marker_size, io);
 190                         rerere_io_putmem(one.buf, one.len, io);
 191                         rerere_io_putconflict('=', marker_size, io);
 192                         rerere_io_putmem(two.buf, two.len, io);
 193                         rerere_io_putconflict('>', marker_size, io);
 194                         if (sha1) {
 195                                 git_SHA1_Update(&ctx, one.buf ? one.buf : "",
 196                                             one.len + 1);
 197                                 git_SHA1_Update(&ctx, two.buf ? two.buf : "",
 198                                             two.len + 1);
 199                         }
 200                         strbuf_reset(&one);
 201                         strbuf_reset(&two);
 202                 } else if (hunk == RR_SIDE_1)
 203                         strbuf_addstr(&one, buf.buf);
 204                 else if (hunk == RR_ORIGINAL)
 205                         ; /* discard */
 206                 else if (hunk == RR_SIDE_2)
 207                         strbuf_addstr(&two, buf.buf);
 208                 else
 209                         rerere_io_putstr(buf.buf, io);
 210                 continue;
 211         bad:
 212                 hunk = 99; /* force error exit */
 213                 break;
 214         }
 215         strbuf_release(&one);
 216         strbuf_release(&two);
 217         strbuf_release(&buf);
 218
 219         if (sha1)
 220                 git_SHA1_Final(sha1, &ctx);
 221         if (hunk != RR_CONTEXT)
 222                 return -1;
 223         return hunk_no;
 224 }
 225
 226 static int handle_file(const char *path, unsigned char *sha1, const char *output)
 227 {
 228         int hunk_no = 0;
 229         struct rerere_io_file io;
 230         int marker_size = ll_merge_marker_size(path);
 231
 232         memset(&io, 0, sizeof(io));
 233         io.io.getline = rerere_file_getline;
 234         io.input = fopen(path, "r");
 235         io.io.wrerror = 0;
 236         if (!io.input)
 237                 return error("Could not open %s", path);
 238
 239         if (output) {
 240                 io.io.output = fopen(output, "w");
 241                 if (!io.io.output) {
 242                         fclose(io.input);
 243                         return error("Could not write %s", output);
 244                 }
 245         }
 246
 247         hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
 248
 249         fclose(io.input);
 250         if (io.io.wrerror)
 251                 error("There were errors while writing %s (%s)",
 252                       path, strerror(io.io.wrerror));
 253         if (io.io.output && fclose(io.io.output))
 254                 io.io.wrerror = error("Failed to flush %s: %s",
 255                                       path, strerror(errno));
 256
 257         if (hunk_no < 0) {
 258                 if (output)
 259                         unlink_or_warn(output);
 260                 return error("Could not parse conflict hunks in %s", path);
 261         }
 262         if (io.io.wrerror)
 263                 return -1;
 264         return hunk_no;
 265 }
 266
 267 struct rerere_io_mem {
 268         struct rerere_io io;
 269         struct strbuf input;
 270 };
 271
 272 static int rerere_mem_getline(struct strbuf *sb, struct rerere_io *io_)
 273 {
 274         struct rerere_io_mem *io = (struct rerere_io_mem *)io_;
 275         char *ep;
 276         size_t len;
 277
 278         strbuf_release(sb);
 279         if (!io->input.len)
 280                 return -1;
 281         ep = strchrnul(io->input.buf, '\n');
 282         if (*ep == '\n')
 283                 ep++;
 284         len = ep - io->input.buf;
 285         strbuf_add(sb, io->input.buf, len);
 286         strbuf_remove(&io->input, 0, len);
 287         return 0;
 288 }
 289
 290 static int handle_cache(const char *path, unsigned char *sha1, const char *output)
 291 {
 292         mmfile_t mmfile[3];
 293         mmbuffer_t result = {NULL, 0};
 294         struct cache_entry *ce;
 295         int pos, len, i, hunk_no;
 296         struct rerere_io_mem io;
 297         int marker_size = ll_merge_marker_size(path);
 298
 299         /*
 300          * Reproduce the conflicted merge in-core
 301          */
 302         len = strlen(path);
 303         pos = cache_name_pos(path, len);
 304         if (0 <= pos)
 305                 return -1;
 306         pos = -pos - 1;
 307
 308         for (i = 0; i < 3; i++) {
 309                 enum object_type type;
 310                 unsigned long size;
 311
 312                 mmfile[i].size = 0;
 313                 mmfile[i].ptr = NULL;
 314                 if (active_nr <= pos)
 315                         break;
 316                 ce = active_cache[pos++];
 317                 if (ce_namelen(ce) != len || memcmp(ce->name, path, len)
 318                     || ce_stage(ce) != i + 1)
 319                         break;
 320                 mmfile[i].ptr = read_sha1_file(ce->sha1, &type, &size);
 321                 mmfile[i].size = size;
 322         }
 323         for (i = 0; i < 3; i++) {
 324                 if (!mmfile[i].ptr && !mmfile[i].size)
 325                         mmfile[i].ptr = xstrdup("");
 326         }
 327         /*
 328          * NEEDSWORK: handle conflicts from merges with
 329          * merge.renormalize set, too
 330          */
 331         ll_merge(&result, path, &mmfile[0], NULL,
 332                  &mmfile[1], "ours",
 333                  &mmfile[2], "theirs", NULL);
 334         for (i = 0; i < 3; i++)
 335                 free(mmfile[i].ptr);
 336
 337         memset(&io, 0, sizeof(io));
 338         io.io.getline = rerere_mem_getline;
 339         if (output)
 340                 io.io.output = fopen(output, "w");
 341         else
 342                 io.io.output = NULL;
 343         strbuf_init(&io.input, 0);
 344         strbuf_attach(&io.input, result.ptr, result.size, result.size);
 345
 346         hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
 347         strbuf_release(&io.input);
 348         if (io.io.output)
 349                 fclose(io.io.output);
 350         return hunk_no;
 351 }
 352
 353 static int check_one_conflict(int i, int *type)
 354 {
 355         struct cache_entry *e = active_cache[i];
 356
 357         if (!ce_stage(e)) {
 358                 *type = RESOLVED;
 359                 return i + 1;
 360         }
 361
 362         *type = PUNTED;
 363         if (ce_stage(e) == 1) {
 364                 if (active_nr <= ++i)
 365                         return i + 1;
 366         }
 367
 368         /* Only handle regular files with both stages #2 and #3 */
 369         if (i + 1 < active_nr) {
 370                 struct cache_entry *e2 = active_cache[i];
 371                 struct cache_entry *e3 = active_cache[i + 1];
 372                 if (ce_stage(e2) == 2 &&
 373                     ce_stage(e3) == 3 &&
 374                     ce_same_name(e, e3) &&
 375                     S_ISREG(e2->ce_mode) &&
 376                     S_ISREG(e3->ce_mode))
 377                         *type = THREE_STAGED;
 378         }
 379
 380         /* Skip the entries with the same name */
 381         while (i < active_nr && ce_same_name(e, active_cache[i]))
 382                 i++;
 383         return i;
 384 }
 385
 386 static int find_conflict(struct string_list *conflict)
 387 {
 388         int i;
 389         if (read_cache() < 0)
 390                 return error("Could not read index");
 391
 392         for (i = 0; i < active_nr;) {
 393                 int conflict_type;
 394                 struct cache_entry *e = active_cache[i];
 395                 i = check_one_conflict(i, &conflict_type);
 396                 if (conflict_type == THREE_STAGED)
 397                         string_list_insert(conflict, (const char *)e->name);
 398         }
 399         return 0;
 400 }
 401
 402 int rerere_remaining(struct string_list *merge_rr)
 403 {
 404         int i;
 405         if (read_cache() < 0)
 406                 return error("Could not read index");
 407
 408         for (i = 0; i < active_nr;) {
 409                 int conflict_type;
 410                 struct cache_entry *e = active_cache[i];
 411                 i = check_one_conflict(i, &conflict_type);
 412                 if (conflict_type == PUNTED)
 413                         string_list_insert(merge_rr, (const char *)e->name);
 414                 else if (conflict_type == RESOLVED) {
 415                         struct string_list_item *it;
 416                         it = string_list_lookup(merge_rr, (const char *)e->name);
 417                         if (it != NULL) {
 418                                 free(it->util);
 419                                 it->util = RERERE_RESOLVED;
 420                         }
 421                 }
 422         }
 423         return 0;
 424 }
 425
 426 static int merge(const char *name, const char *path)
 427 {
 428         int ret;
 429         mmfile_t cur = {NULL, 0}, base = {NULL, 0}, other = {NULL, 0};
 430         mmbuffer_t result = {NULL, 0};
 431
 432         if (handle_file(path, NULL, rerere_path(name, "thisimage")) < 0)
 433                 return 1;
 434
 435         if (read_mmfile(&cur, rerere_path(name, "thisimage")) ||
 436                         read_mmfile(&base, rerere_path(name, "preimage")) ||
 437                         read_mmfile(&other, rerere_path(name, "postimage"))) {
 438                 ret = 1;
 439                 goto out;
 440         }
 441         ret = ll_merge(&result, path, &base, NULL, &cur, "", &other, "", 0);
 442         if (!ret) {
 443                 FILE *f;
 444
 445                 if (utime(rerere_path(name, "postimage"), NULL) < 0)
 446                         warning("failed utime() on %s: %s",
 447                                         rerere_path(name, "postimage"),
 448                                         strerror(errno));
 449                 f = fopen(path, "w");
 450                 if (!f)
 451                         return error("Could not open %s: %s", path,
 452                                      strerror(errno));
 453                 if (fwrite(result.ptr, result.size, 1, f) != 1)
 454                         error("Could not write %s: %s", path, strerror(errno));
 455                 if (fclose(f))
 456                         return error("Writing %s failed: %s", path,
 457                                      strerror(errno));
 458         }
 459
 460 out:
 461         free(cur.ptr);
 462         free(base.ptr);
 463         free(other.ptr);
 464         free(result.ptr);
 465
 466         return ret;
 467 }
 468
 469 static struct lock_file index_lock;
 470
 471 static int update_paths(struct string_list *update)
 472 {
 473         int i;
 474         int fd = hold_locked_index(&index_lock, 0);
 475         int status = 0;
 476
 477         if (fd < 0)
 478                 return -1;
 479
 480         for (i = 0; i < update->nr; i++) {
 481                 struct string_list_item *item = &update->items[i];
 482                 if (add_file_to_cache(item->string, ADD_CACHE_IGNORE_ERRORS))
 483                         status = -1;
 484         }
 485
 486         if (!status && active_cache_changed) {
 487                 if (write_cache(fd, active_cache, active_nr) ||
 488                     commit_locked_index(&index_lock))
 489                         die("Unable to write new index file");
 490         } else if (fd >= 0)
 491                 rollback_lock_file(&index_lock);
 492         return status;
 493 }
 494
 495 static int do_plain_rerere(struct string_list *rr, int fd)
 496 {
 497         struct string_list conflict = STRING_LIST_INIT_DUP;
 498         struct string_list update = STRING_LIST_INIT_DUP;
 499         int i;
 500
 501         find_conflict(&conflict);
 502
 503         /*
 504          * MERGE_RR records paths with conflicts immediately after merge
 505          * failed.  Some of the conflicted paths might have been hand resolved
 506          * in the working tree since then, but the initial run would catch all
 507          * and register their preimages.
 508          */
 509
 510         for (i = 0; i < conflict.nr; i++) {
 511                 const char *path = conflict.items[i].string;
 512                 if (!string_list_has_string(rr, path)) {
 513                         unsigned char sha1[20];
 514                         char *hex;
 515                         int ret;
 516                         ret = handle_file(path, sha1, NULL);
 517                         if (ret < 1)
 518                                 continue;
 519                         hex = xstrdup(sha1_to_hex(sha1));
 520                         string_list_insert(rr, path)->util = hex;
 521                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 522                                 continue;
 523                         handle_file(path, NULL, rerere_path(hex, "preimage"));
 524                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 525                 }
 526         }
 527
 528         /*
 529          * Now some of the paths that had conflicts earlier might have been
 530          * hand resolved.  Others may be similar to a conflict already that
 531          * was resolved before.
 532          */
 533
 534         for (i = 0; i < rr->nr; i++) {
 535                 int ret;
 536                 const char *path = rr->items[i].string;
 537                 const char *name = (const char *)rr->items[i].util;
 538
 539                 if (has_rerere_resolution(name)) {
 540                         if (!merge(name, path)) {
 541                                 if (rerere_autoupdate)
 542                                         string_list_insert(&update, path);
 543                                 fprintf(stderr,
 544                                         "%s '%s' using previous resolution.\n",
 545                                         rerere_autoupdate
 546                                         ? "Staged" : "Resolved",
 547                                         path);
 548                                 goto mark_resolved;
 549                         }
 550                 }
 551
 552                 /* Let's see if we have resolved it. */
 553                 ret = handle_file(path, NULL, NULL);
 554                 if (ret)
 555                         continue;
 556
 557                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 558                 copy_file(rerere_path(name, "postimage"), path, 0666);
 559         mark_resolved:
 560                 rr->items[i].util = NULL;
 561         }
 562
 563         if (update.nr)
 564                 update_paths(&update);
 565
 566         return write_rr(rr, fd);
 567 }
 568
 569 static int git_rerere_config(const char *var, const char *value, void *cb)
 570 {
 571         if (!strcmp(var, "rerere.enabled"))
 572                 rerere_enabled = git_config_bool(var, value);
 573         else if (!strcmp(var, "rerere.autoupdate"))
 574                 rerere_autoupdate = git_config_bool(var, value);
 575         else
 576                 return git_default_config(var, value, cb);
 577         return 0;
 578 }
 579
 580 static int is_rerere_enabled(void)
 581 {
 582         const char *rr_cache;
 583         int rr_cache_exists;
 584
 585         if (!rerere_enabled)
 586                 return 0;
 587
 588         rr_cache = git_path("rr-cache");
 589         rr_cache_exists = is_directory(rr_cache);
 590         if (rerere_enabled < 0)
 591                 return rr_cache_exists;
 592
 593         if (!rr_cache_exists &&
 594             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 595                 die("Could not create directory %s", rr_cache);
 596         return 1;
 597 }
 598
 599 int setup_rerere(struct string_list *merge_rr, int flags)
 600 {
 601         int fd;
 602
 603         git_config(git_rerere_config, NULL);
 604         if (!is_rerere_enabled())
 605                 return -1;
 606
 607         if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE))
 608                 rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE);
 609         merge_rr_path = git_pathdup("MERGE_RR");
 610         fd = hold_lock_file_for_update(&write_lock, merge_rr_path,
 611                                        LOCK_DIE_ON_ERROR);
 612         read_rr(merge_rr);
 613         return fd;
 614 }
 615
 616 int rerere(int flags)
 617 {
 618         struct string_list merge_rr = STRING_LIST_INIT_DUP;
 619         int fd;
 620
 621         fd = setup_rerere(&merge_rr, flags);
 622         if (fd < 0)
 623                 return 0;
 624         return do_plain_rerere(&merge_rr, fd);
 625 }
 626
 627 static int rerere_forget_one_path(const char *path, struct string_list *rr)
 628 {
 629         const char *filename;
 630         char *hex;
 631         unsigned char sha1[20];
 632         int ret;
 633
 634         ret = handle_cache(path, sha1, NULL);
 635         if (ret < 1)
 636                 return error("Could not parse conflict hunks in '%s'", path);
 637         hex = xstrdup(sha1_to_hex(sha1));
 638         filename = rerere_path(hex, "postimage");
 639         if (unlink(filename))
 640                 return (errno == ENOENT
 641                         ? error("no remembered resolution for %s", path)
 642                         : error("cannot unlink %s: %s", filename, strerror(errno)));
 643
 644         handle_cache(path, sha1, rerere_path(hex, "preimage"));
 645         fprintf(stderr, "Updated preimage for '%s'\n", path);
 646
 647
 648         string_list_insert(rr, path)->util = hex;
 649         fprintf(stderr, "Forgot resolution for %s\n", path);
 650         return 0;
 651 }
 652
 653 int rerere_forget(const char **pathspec)
 654 {
 655         int i, fd;
 656         struct string_list conflict = STRING_LIST_INIT_DUP;
 657         struct string_list merge_rr = STRING_LIST_INIT_DUP;
 658
 659         if (read_cache() < 0)
 660                 return error("Could not read index");
 661
 662         fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
 663
 664         unmerge_cache(pathspec);
 665         find_conflict(&conflict);
 666         for (i = 0; i < conflict.nr; i++) {
 667                 struct string_list_item *it = &conflict.items[i];
 668                 if (!match_pathspec(pathspec, it->string, strlen(it->string),
 669                                     0, NULL))
 670                         continue;
 671                 rerere_forget_one_path(it->string, &merge_rr);
 672         }
 673         return write_rr(&merge_rr, fd);
 674 }