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