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); i++) {
  51                         int c = fgetc(in);
  52                         if (c < 0)
  53                                 die("corrupt MERGE_RR");
  54                         buf[i] = c;
  55                         if (c == 0)
  56                                  break;
  57                 }
  58                 if (i == sizeof(buf))
  59                         die("filename too long");
  60                 string_list_insert(rr, buf)->util = name;
  61         }
  62         fclose(in);
  63 }
  64
  65 static struct lock_file write_lock;
  66
  67 static int write_rr(struct string_list *rr, int out_fd)
  68 {
  69         int i;
  70         for (i = 0; i < rr->nr; i++) {
  71                 const char *path;
  72                 int length;
  73                 if (!rr->items[i].util)
  74                         continue;
  75                 path = rr->items[i].string;
  76                 length = strlen(path) + 1;
  77                 if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
  78                     write_str_in_full(out_fd, "\t") != 1 ||
  79                     write_in_full(out_fd, path, length) != length)
  80                         die("unable to write rerere record");
  81         }
  82         if (commit_lock_file(&write_lock) != 0)
  83                 die("unable to write rerere record");
  84         return 0;
  85 }
  86
  87 static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
  88 {
  89         if (!count || *err)
  90                 return;
  91         if (fwrite(p, count, 1, fp) != 1)
  92                 *err = errno;
  93 }
  94
  95 static inline void ferr_puts(const char *s, FILE *fp, int *err)
  96 {
  97         ferr_write(s, strlen(s), fp, err);
  98 }
  99
 100 struct rerere_io {
 101         int (*getline)(struct strbuf *, struct rerere_io *);
 102         FILE *output;
 103         int wrerror;
 104         /* some more stuff */
 105 };
 106
 107 static void rerere_io_putstr(const char *str, struct rerere_io *io)
 108 {
 109         if (io->output)
 110                 ferr_puts(str, io->output, &io->wrerror);
 111 }
 112
 113 static void rerere_io_putconflict(int ch, int size, struct rerere_io *io)
 114 {
 115         char buf[64];
 116
 117         while (size) {
 118                 if (size < sizeof(buf) - 2) {
 119                         memset(buf, ch, size);
 120                         buf[size] = '\n';
 121                         buf[size + 1] = '\0';
 122                         size = 0;
 123                 } else {
 124                         int sz = sizeof(buf) - 1;
 125                         if (size <= sz)
 126                                 sz -= (sz - size) + 1;
 127                         memset(buf, ch, sz);
 128                         buf[sz] = '\0';
 129                         size -= sz;
 130                 }
 131                 rerere_io_putstr(buf, io);
 132         }
 133 }
 134
 135 static void rerere_io_putmem(const char *mem, size_t sz, struct rerere_io *io)
 136 {
 137         if (io->output)
 138                 ferr_write(mem, sz, io->output, &io->wrerror);
 139 }
 140
 141 struct rerere_io_file {
 142         struct rerere_io io;
 143         FILE *input;
 144 };
 145
 146 static int rerere_file_getline(struct strbuf *sb, struct rerere_io *io_)
 147 {
 148         struct rerere_io_file *io = (struct rerere_io_file *)io_;
 149         return strbuf_getwholeline(sb, io->input, '\n');
 150 }
 151
 152 static int is_cmarker(char *buf, int marker_char, int marker_size, int want_sp)
 153 {
 154         while (marker_size--)
 155                 if (*buf++ != marker_char)
 156                         return 0;
 157         if (want_sp && *buf != ' ')
 158                 return 0;
 159         return isspace(*buf);
 160 }
 161
 162 static int handle_path(unsigned char *sha1, struct rerere_io *io, int marker_size)
 163 {
 164         git_SHA_CTX ctx;
 165         int hunk_no = 0;
 166         enum {
 167                 RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL
 168         } hunk = RR_CONTEXT;
 169         struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
 170         struct strbuf buf = STRBUF_INIT;
 171
 172         if (sha1)
 173                 git_SHA1_Init(&ctx);
 174
 175         while (!io->getline(&buf, io)) {
 176                 if (is_cmarker(buf.buf, '<', marker_size, 1)) {
 177                         if (hunk != RR_CONTEXT)
 178                                 goto bad;
 179                         hunk = RR_SIDE_1;
 180                 } else if (is_cmarker(buf.buf, '|', marker_size, 0)) {
 181                         if (hunk != RR_SIDE_1)
 182                                 goto bad;
 183                         hunk = RR_ORIGINAL;
 184                 } else if (is_cmarker(buf.buf, '=', marker_size, 0)) {
 185                         if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
 186                                 goto bad;
 187                         hunk = RR_SIDE_2;
 188                 } else if (is_cmarker(buf.buf, '>', marker_size, 1)) {
 189                         if (hunk != RR_SIDE_2)
 190                                 goto bad;
 191                         if (strbuf_cmp(&one, &two) > 0)
 192                                 strbuf_swap(&one, &two);
 193                         hunk_no++;
 194                         hunk = RR_CONTEXT;
 195                         rerere_io_putconflict('<', marker_size, io);
 196                         rerere_io_putmem(one.buf, one.len, io);
 197                         rerere_io_putconflict('=', marker_size, io);
 198                         rerere_io_putmem(two.buf, two.len, io);
 199                         rerere_io_putconflict('>', marker_size, io);
 200                         if (sha1) {
 201                                 git_SHA1_Update(&ctx, one.buf ? one.buf : "",
 202                                             one.len + 1);
 203                                 git_SHA1_Update(&ctx, two.buf ? two.buf : "",
 204                                             two.len + 1);
 205                         }
 206                         strbuf_reset(&one);
 207                         strbuf_reset(&two);
 208                 } else if (hunk == RR_SIDE_1)
 209                         strbuf_addstr(&one, buf.buf);
 210                 else if (hunk == RR_ORIGINAL)
 211                         ; /* discard */
 212                 else if (hunk == RR_SIDE_2)
 213                         strbuf_addstr(&two, buf.buf);
 214                 else
 215                         rerere_io_putstr(buf.buf, io);
 216                 continue;
 217         bad:
 218                 hunk = 99; /* force error exit */
 219                 break;
 220         }
 221         strbuf_release(&one);
 222         strbuf_release(&two);
 223         strbuf_release(&buf);
 224
 225         if (sha1)
 226                 git_SHA1_Final(sha1, &ctx);
 227         if (hunk != RR_CONTEXT)
 228                 return -1;
 229         return hunk_no;
 230 }
 231
 232 static int handle_file(const char *path, unsigned char *sha1, const char *output)
 233 {
 234         int hunk_no = 0;
 235         struct rerere_io_file io;
 236         int marker_size = ll_merge_marker_size(path);
 237
 238         memset(&io, 0, sizeof(io));
 239         io.io.getline = rerere_file_getline;
 240         io.input = fopen(path, "r");
 241         io.io.wrerror = 0;
 242         if (!io.input)
 243                 return error("Could not open %s", path);
 244
 245         if (output) {
 246                 io.io.output = fopen(output, "w");
 247                 if (!io.io.output) {
 248                         fclose(io.input);
 249                         return error("Could not write %s", output);
 250                 }
 251         }
 252
 253         hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
 254
 255         fclose(io.input);
 256         if (io.io.wrerror)
 257                 error("There were errors while writing %s (%s)",
 258                       path, strerror(io.io.wrerror));
 259         if (io.io.output && fclose(io.io.output))
 260                 io.io.wrerror = error("Failed to flush %s: %s",
 261                                       path, strerror(errno));
 262
 263         if (hunk_no < 0) {
 264                 if (output)
 265                         unlink_or_warn(output);
 266                 return error("Could not parse conflict hunks in %s", path);
 267         }
 268         if (io.io.wrerror)
 269                 return -1;
 270         return hunk_no;
 271 }
 272
 273 struct rerere_io_mem {
 274         struct rerere_io io;
 275         struct strbuf input;
 276 };
 277
 278 static int rerere_mem_getline(struct strbuf *sb, struct rerere_io *io_)
 279 {
 280         struct rerere_io_mem *io = (struct rerere_io_mem *)io_;
 281         char *ep;
 282         size_t len;
 283
 284         strbuf_release(sb);
 285         if (!io->input.len)
 286                 return -1;
 287         ep = strchrnul(io->input.buf, '\n');
 288         if (*ep == '\n')
 289                 ep++;
 290         len = ep - io->input.buf;
 291         strbuf_add(sb, io->input.buf, len);
 292         strbuf_remove(&io->input, 0, len);
 293         return 0;
 294 }
 295
 296 static int handle_cache(const char *path, unsigned char *sha1, const char *output)
 297 {
 298         mmfile_t mmfile[3];
 299         mmbuffer_t result = {NULL, 0};
 300         struct cache_entry *ce;
 301         int pos, len, i, hunk_no;
 302         struct rerere_io_mem io;
 303         int marker_size = ll_merge_marker_size(path);
 304
 305         /*
 306          * Reproduce the conflicted merge in-core
 307          */
 308         len = strlen(path);
 309         pos = cache_name_pos(path, len);
 310         if (0 <= pos)
 311                 return -1;
 312         pos = -pos - 1;
 313
 314         for (i = 0; i < 3; i++) {
 315                 enum object_type type;
 316                 unsigned long size;
 317
 318                 mmfile[i].size = 0;
 319                 mmfile[i].ptr = NULL;
 320                 if (active_nr <= pos)
 321                         break;
 322                 ce = active_cache[pos++];
 323                 if (ce_namelen(ce) != len || memcmp(ce->name, path, len)
 324                     || ce_stage(ce) != i + 1)
 325                         break;
 326                 mmfile[i].ptr = read_sha1_file(ce->sha1, &type, &size);
 327                 mmfile[i].size = size;
 328         }
 329         for (i = 0; i < 3; i++) {
 330                 if (!mmfile[i].ptr && !mmfile[i].size)
 331                         mmfile[i].ptr = xstrdup("");
 332         }
 333         /*
 334          * NEEDSWORK: handle conflicts from merges with
 335          * merge.renormalize set, too
 336          */
 337         ll_merge(&result, path, &mmfile[0], NULL,
 338                  &mmfile[1], "ours",
 339                  &mmfile[2], "theirs", NULL);
 340         for (i = 0; i < 3; i++)
 341                 free(mmfile[i].ptr);
 342
 343         memset(&io, 0, sizeof(io));
 344         io.io.getline = rerere_mem_getline;
 345         if (output)
 346                 io.io.output = fopen(output, "w");
 347         else
 348                 io.io.output = NULL;
 349         strbuf_init(&io.input, 0);
 350         strbuf_attach(&io.input, result.ptr, result.size, result.size);
 351
 352         hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
 353         strbuf_release(&io.input);
 354         if (io.io.output)
 355                 fclose(io.io.output);
 356         return hunk_no;
 357 }
 358
 359 static int check_one_conflict(int i, int *type)
 360 {
 361         struct cache_entry *e = active_cache[i];
 362
 363         if (!ce_stage(e)) {
 364                 *type = RESOLVED;
 365                 return i + 1;
 366         }
 367
 368         *type = PUNTED;
 369         if (ce_stage(e) == 1) {
 370                 if (active_nr <= ++i)
 371                         return i + 1;
 372         }
 373
 374         /* Only handle regular files with both stages #2 and #3 */
 375         if (i + 1 < active_nr) {
 376                 struct cache_entry *e2 = active_cache[i];
 377                 struct cache_entry *e3 = active_cache[i + 1];
 378                 if (ce_stage(e2) == 2 &&
 379                     ce_stage(e3) == 3 &&
 380                     ce_same_name(e, e3) &&
 381                     S_ISREG(e2->ce_mode) &&
 382                     S_ISREG(e3->ce_mode))
 383                         *type = THREE_STAGED;
 384         }
 385
 386         /* Skip the entries with the same name */
 387         while (i < active_nr && ce_same_name(e, active_cache[i]))
 388                 i++;
 389         return i;
 390 }
 391
 392 static int find_conflict(struct string_list *conflict)
 393 {
 394         int i;
 395         if (read_cache() < 0)
 396                 return error("Could not read index");
 397
 398         for (i = 0; i < active_nr;) {
 399                 int conflict_type;
 400                 struct cache_entry *e = active_cache[i];
 401                 i = check_one_conflict(i, &conflict_type);
 402                 if (conflict_type == THREE_STAGED)
 403                         string_list_insert(conflict, (const char *)e->name);
 404         }
 405         return 0;
 406 }
 407
 408 int rerere_remaining(struct string_list *merge_rr)
 409 {
 410         int i;
 411         if (read_cache() < 0)
 412                 return error("Could not read index");
 413
 414         for (i = 0; i < active_nr;) {
 415                 int conflict_type;
 416                 struct cache_entry *e = active_cache[i];
 417                 i = check_one_conflict(i, &conflict_type);
 418                 if (conflict_type == PUNTED)
 419                         string_list_insert(merge_rr, (const char *)e->name);
 420                 else if (conflict_type == RESOLVED) {
 421                         struct string_list_item *it;
 422                         it = string_list_lookup(merge_rr, (const char *)e->name);
 423                         if (it != NULL) {
 424                                 free(it->util);
 425                                 it->util = RERERE_RESOLVED;
 426                         }
 427                 }
 428         }
 429         return 0;
 430 }
 431
 432 static int merge(const char *name, const char *path)
 433 {
 434         int ret;
 435         mmfile_t cur = {NULL, 0}, base = {NULL, 0}, other = {NULL, 0};
 436         mmbuffer_t result = {NULL, 0};
 437
 438         if (handle_file(path, NULL, rerere_path(name, "thisimage")) < 0)
 439                 return 1;
 440
 441         if (read_mmfile(&cur, rerere_path(name, "thisimage")) ||
 442                         read_mmfile(&base, rerere_path(name, "preimage")) ||
 443                         read_mmfile(&other, rerere_path(name, "postimage"))) {
 444                 ret = 1;
 445                 goto out;
 446         }
 447         ret = ll_merge(&result, path, &base, NULL, &cur, "", &other, "", NULL);
 448         if (!ret) {
 449                 FILE *f;
 450
 451                 if (utime(rerere_path(name, "postimage"), NULL) < 0)
 452                         warning("failed utime() on %s: %s",
 453                                         rerere_path(name, "postimage"),
 454                                         strerror(errno));
 455                 f = fopen(path, "w");
 456                 if (!f)
 457                         return error("Could not open %s: %s", path,
 458                                      strerror(errno));
 459                 if (fwrite(result.ptr, result.size, 1, f) != 1)
 460                         error("Could not write %s: %s", path, strerror(errno));
 461                 if (fclose(f))
 462                         return error("Writing %s failed: %s", path,
 463                                      strerror(errno));
 464         }
 465
 466 out:
 467         free(cur.ptr);
 468         free(base.ptr);
 469         free(other.ptr);
 470         free(result.ptr);
 471
 472         return ret;
 473 }
 474
 475 static struct lock_file index_lock;
 476
 477 static int update_paths(struct string_list *update)
 478 {
 479         int i;
 480         int fd = hold_locked_index(&index_lock, 0);
 481         int status = 0;
 482
 483         if (fd < 0)
 484                 return -1;
 485
 486         for (i = 0; i < update->nr; i++) {
 487                 struct string_list_item *item = &update->items[i];
 488                 if (add_file_to_cache(item->string, ADD_CACHE_IGNORE_ERRORS))
 489                         status = -1;
 490         }
 491
 492         if (!status && active_cache_changed) {
 493                 if (write_cache(fd, active_cache, active_nr) ||
 494                     commit_locked_index(&index_lock))
 495                         die("Unable to write new index file");
 496         } else if (fd >= 0)
 497                 rollback_lock_file(&index_lock);
 498         return status;
 499 }
 500
 501 static int do_plain_rerere(struct string_list *rr, int fd)
 502 {
 503         struct string_list conflict = STRING_LIST_INIT_DUP;
 504         struct string_list update = STRING_LIST_INIT_DUP;
 505         int i;
 506
 507         find_conflict(&conflict);
 508
 509         /*
 510          * MERGE_RR records paths with conflicts immediately after merge
 511          * failed.  Some of the conflicted paths might have been hand resolved
 512          * in the working tree since then, but the initial run would catch all
 513          * and register their preimages.
 514          */
 515
 516         for (i = 0; i < conflict.nr; i++) {
 517                 const char *path = conflict.items[i].string;
 518                 if (!string_list_has_string(rr, path)) {
 519                         unsigned char sha1[20];
 520                         char *hex;
 521                         int ret;
 522                         ret = handle_file(path, sha1, NULL);
 523                         if (ret < 1)
 524                                 continue;
 525                         hex = xstrdup(sha1_to_hex(sha1));
 526                         string_list_insert(rr, path)->util = hex;
 527                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 528                                 continue;
 529                         handle_file(path, NULL, rerere_path(hex, "preimage"));
 530                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 531                 }
 532         }
 533
 534         /*
 535          * Now some of the paths that had conflicts earlier might have been
 536          * hand resolved.  Others may be similar to a conflict already that
 537          * was resolved before.
 538          */
 539
 540         for (i = 0; i < rr->nr; i++) {
 541                 int ret;
 542                 const char *path = rr->items[i].string;
 543                 const char *name = (const char *)rr->items[i].util;
 544
 545                 if (has_rerere_resolution(name)) {
 546                         if (!merge(name, path)) {
 547                                 if (rerere_autoupdate)
 548                                         string_list_insert(&update, path);
 549                                 fprintf(stderr,
 550                                         "%s '%s' using previous resolution.\n",
 551                                         rerere_autoupdate
 552                                         ? "Staged" : "Resolved",
 553                                         path);
 554                                 goto mark_resolved;
 555                         }
 556                 }
 557
 558                 /* Let's see if we have resolved it. */
 559                 ret = handle_file(path, NULL, NULL);
 560                 if (ret)
 561                         continue;
 562
 563                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 564                 copy_file(rerere_path(name, "postimage"), path, 0666);
 565         mark_resolved:
 566                 rr->items[i].util = NULL;
 567         }
 568
 569         if (update.nr)
 570                 update_paths(&update);
 571
 572         return write_rr(rr, fd);
 573 }
 574
 575 static int git_rerere_config(const char *var, const char *value, void *cb)
 576 {
 577         if (!strcmp(var, "rerere.enabled"))
 578                 rerere_enabled = git_config_bool(var, value);
 579         else if (!strcmp(var, "rerere.autoupdate"))
 580                 rerere_autoupdate = git_config_bool(var, value);
 581         else
 582                 return git_default_config(var, value, cb);
 583         return 0;
 584 }
 585
 586 static int is_rerere_enabled(void)
 587 {
 588         const char *rr_cache;
 589         int rr_cache_exists;
 590
 591         if (!rerere_enabled)
 592                 return 0;
 593
 594         rr_cache = git_path("rr-cache");
 595         rr_cache_exists = is_directory(rr_cache);
 596         if (rerere_enabled < 0)
 597                 return rr_cache_exists;
 598
 599         if (!rr_cache_exists && mkdir_in_gitdir(rr_cache))
 600                 die("Could not create directory %s", rr_cache);
 601         return 1;
 602 }
 603
 604 int setup_rerere(struct string_list *merge_rr, int flags)
 605 {
 606         int fd;
 607
 608         git_config(git_rerere_config, NULL);
 609         if (!is_rerere_enabled())
 610                 return -1;
 611
 612         if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE))
 613                 rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE);
 614         merge_rr_path = git_pathdup("MERGE_RR");
 615         fd = hold_lock_file_for_update(&write_lock, merge_rr_path,
 616                                        LOCK_DIE_ON_ERROR);
 617         read_rr(merge_rr);
 618         return fd;
 619 }
 620
 621 int rerere(int flags)
 622 {
 623         struct string_list merge_rr = STRING_LIST_INIT_DUP;
 624         int fd;
 625
 626         fd = setup_rerere(&merge_rr, flags);
 627         if (fd < 0)
 628                 return 0;
 629         return do_plain_rerere(&merge_rr, fd);
 630 }
 631
 632 static int rerere_forget_one_path(const char *path, struct string_list *rr)
 633 {
 634         const char *filename;
 635         char *hex;
 636         unsigned char sha1[20];
 637         int ret;
 638
 639         ret = handle_cache(path, sha1, NULL);
 640         if (ret < 1)
 641                 return error("Could not parse conflict hunks in '%s'", path);
 642         hex = xstrdup(sha1_to_hex(sha1));
 643         filename = rerere_path(hex, "postimage");
 644         if (unlink(filename))
 645                 return (errno == ENOENT
 646                         ? error("no remembered resolution for %s", path)
 647                         : error("cannot unlink %s: %s", filename, strerror(errno)));
 648
 649         handle_cache(path, sha1, rerere_path(hex, "preimage"));
 650         fprintf(stderr, "Updated preimage for '%s'\n", path);
 651
 652
 653         string_list_insert(rr, path)->util = hex;
 654         fprintf(stderr, "Forgot resolution for %s\n", path);
 655         return 0;
 656 }
 657
 658 int rerere_forget(const char **pathspec)
 659 {
 660         int i, fd;
 661         struct string_list conflict = STRING_LIST_INIT_DUP;
 662         struct string_list merge_rr = STRING_LIST_INIT_DUP;
 663
 664         if (read_cache() < 0)
 665                 return error("Could not read index");
 666
 667         fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
 668
 669         unmerge_cache(pathspec);
 670         find_conflict(&conflict);
 671         for (i = 0; i < conflict.nr; i++) {
 672                 struct string_list_item *it = &conflict.items[i];
 673                 if (!match_pathspec(pathspec, it->string, strlen(it->string),
 674                                     0, NULL))
 675                         continue;
 676                 rerere_forget_one_path(it->string, &merge_rr);
 677         }
 678         return write_rr(&merge_rr, fd);
 679 }