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 /* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
  11 static int rerere_enabled = -1;
  12
  13 /* automatically update cleanly resolved paths to the index */
  14 static int rerere_autoupdate;
  15
  16 static char *merge_rr_path;
  17
  18 const char *rerere_path(const char *hex, const char *file)
  19 {
  20         return git_path("rr-cache/%s/%s", hex, file);
  21 }
  22
  23 int has_rerere_resolution(const char *hex)
  24 {
  25         struct stat st;
  26         return !stat(rerere_path(hex, "postimage"), &st);
  27 }
  28
  29 static 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(buf, rr)->util = name;
  50         }
  51         fclose(in);
  52 }
  53
  54 static struct lock_file write_lock;
  55
  56 static 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
  76 static 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
  84 static inline void ferr_puts(const char *s, FILE *fp, int *err)
  85 {
  86         ferr_write(s, strlen(s), fp, err);
  87 }
  88
  89 struct rerere_io {
  90         int (*getline)(struct strbuf *, struct rerere_io *);
  91         FILE *output;
  92         int wrerror;
  93         /* some more stuff */
  94 };
  95
  96 static 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
 102 static 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
 124 static 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
 130 struct rerere_io_file {
 131         struct rerere_io io;
 132         FILE *input;
 133 };
 134
 135 static 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
 141 static 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
 151 static 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
 221 static 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
 262 struct rerere_io_mem {
 263         struct rerere_io io;
 264         struct strbuf input;
 265 };
 266
 267 static 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
 285 static 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         ll_merge(&result, path, &mmfile[0], NULL,
 323                  &mmfile[1], "ours",
 324                  &mmfile[2], "theirs", 0);
 325         for (i = 0; i < 3; i++)
 326                 free(mmfile[i].ptr);
 327
 328         memset(&io, 0, sizeof(io));
 329         io.io.getline = rerere_mem_getline;
 330         if (output)
 331                 io.io.output = fopen(output, "w");
 332         else
 333                 io.io.output = NULL;
 334         strbuf_init(&io.input, 0);
 335         strbuf_attach(&io.input, result.ptr, result.size, result.size);
 336
 337         hunk_no = handle_path(sha1, (struct rerere_io *)&io, marker_size);
 338         strbuf_release(&io.input);
 339         if (io.io.output)
 340                 fclose(io.io.output);
 341         return hunk_no;
 342 }
 343
 344 static int find_conflict(struct string_list *conflict)
 345 {
 346         int i;
 347         if (read_cache() < 0)
 348                 return error("Could not read index");
 349         for (i = 0; i+1 < active_nr; i++) {
 350                 struct cache_entry *e2 = active_cache[i];
 351                 struct cache_entry *e3 = active_cache[i+1];
 352                 if (ce_stage(e2) == 2 &&
 353                     ce_stage(e3) == 3 &&
 354                     ce_same_name(e2, e3) &&
 355                     S_ISREG(e2->ce_mode) &&
 356                     S_ISREG(e3->ce_mode)) {
 357                         string_list_insert((const char *)e2->name, conflict);
 358                         i++; /* skip over both #2 and #3 */
 359                 }
 360         }
 361         return 0;
 362 }
 363
 364 static int merge(const char *name, const char *path)
 365 {
 366         int ret;
 367         mmfile_t cur = {NULL, 0}, base = {NULL, 0}, other = {NULL, 0};
 368         mmbuffer_t result = {NULL, 0};
 369
 370         if (handle_file(path, NULL, rerere_path(name, "thisimage")) < 0)
 371                 return 1;
 372
 373         if (read_mmfile(&cur, rerere_path(name, "thisimage")) ||
 374                         read_mmfile(&base, rerere_path(name, "preimage")) ||
 375                         read_mmfile(&other, rerere_path(name, "postimage"))) {
 376                 ret = 1;
 377                 goto out;
 378         }
 379         ret = ll_merge(&result, path, &base, NULL, &cur, "", &other, "", 0);
 380         if (!ret) {
 381                 FILE *f;
 382
 383                 if (utime(rerere_path(name, "postimage"), NULL) < 0)
 384                         warning("failed utime() on %s: %s",
 385                                         rerere_path(name, "postimage"),
 386                                         strerror(errno));
 387                 f = fopen(path, "w");
 388                 if (!f)
 389                         return error("Could not open %s: %s", path,
 390                                      strerror(errno));
 391                 if (fwrite(result.ptr, result.size, 1, f) != 1)
 392                         error("Could not write %s: %s", path, strerror(errno));
 393                 if (fclose(f))
 394                         return error("Writing %s failed: %s", path,
 395                                      strerror(errno));
 396         }
 397
 398 out:
 399         free(cur.ptr);
 400         free(base.ptr);
 401         free(other.ptr);
 402         free(result.ptr);
 403
 404         return ret;
 405 }
 406
 407 static struct lock_file index_lock;
 408
 409 static int update_paths(struct string_list *update)
 410 {
 411         int i;
 412         int fd = hold_locked_index(&index_lock, 0);
 413         int status = 0;
 414
 415         if (fd < 0)
 416                 return -1;
 417
 418         for (i = 0; i < update->nr; i++) {
 419                 struct string_list_item *item = &update->items[i];
 420                 if (add_file_to_cache(item->string, ADD_CACHE_IGNORE_ERRORS))
 421                         status = -1;
 422         }
 423
 424         if (!status && active_cache_changed) {
 425                 if (write_cache(fd, active_cache, active_nr) ||
 426                     commit_locked_index(&index_lock))
 427                         die("Unable to write new index file");
 428         } else if (fd >= 0)
 429                 rollback_lock_file(&index_lock);
 430         return status;
 431 }
 432
 433 static int do_plain_rerere(struct string_list *rr, int fd)
 434 {
 435         struct string_list conflict = { NULL, 0, 0, 1 };
 436         struct string_list update = { NULL, 0, 0, 1 };
 437         int i;
 438
 439         find_conflict(&conflict);
 440
 441         /*
 442          * MERGE_RR records paths with conflicts immediately after merge
 443          * failed.  Some of the conflicted paths might have been hand resolved
 444          * in the working tree since then, but the initial run would catch all
 445          * and register their preimages.
 446          */
 447
 448         for (i = 0; i < conflict.nr; i++) {
 449                 const char *path = conflict.items[i].string;
 450                 if (!string_list_has_string(rr, path)) {
 451                         unsigned char sha1[20];
 452                         char *hex;
 453                         int ret;
 454                         ret = handle_file(path, sha1, NULL);
 455                         if (ret < 1)
 456                                 continue;
 457                         hex = xstrdup(sha1_to_hex(sha1));
 458                         string_list_insert(path, rr)->util = hex;
 459                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 460                                 continue;
 461                         handle_file(path, NULL, rerere_path(hex, "preimage"));
 462                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 463                 }
 464         }
 465
 466         /*
 467          * Now some of the paths that had conflicts earlier might have been
 468          * hand resolved.  Others may be similar to a conflict already that
 469          * was resolved before.
 470          */
 471
 472         for (i = 0; i < rr->nr; i++) {
 473                 int ret;
 474                 const char *path = rr->items[i].string;
 475                 const char *name = (const char *)rr->items[i].util;
 476
 477                 if (has_rerere_resolution(name)) {
 478                         if (!merge(name, path)) {
 479                                 if (rerere_autoupdate)
 480                                         string_list_insert(path, &update);
 481                                 fprintf(stderr,
 482                                         "%s '%s' using previous resolution.\n",
 483                                         rerere_autoupdate
 484                                         ? "Staged" : "Resolved",
 485                                         path);
 486                                 goto mark_resolved;
 487                         }
 488                 }
 489
 490                 /* Let's see if we have resolved it. */
 491                 ret = handle_file(path, NULL, NULL);
 492                 if (ret)
 493                         continue;
 494
 495                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 496                 copy_file(rerere_path(name, "postimage"), path, 0666);
 497         mark_resolved:
 498                 rr->items[i].util = NULL;
 499         }
 500
 501         if (update.nr)
 502                 update_paths(&update);
 503
 504         return write_rr(rr, fd);
 505 }
 506
 507 static int git_rerere_config(const char *var, const char *value, void *cb)
 508 {
 509         if (!strcmp(var, "rerere.enabled"))
 510                 rerere_enabled = git_config_bool(var, value);
 511         else if (!strcmp(var, "rerere.autoupdate"))
 512                 rerere_autoupdate = git_config_bool(var, value);
 513         else
 514                 return git_default_config(var, value, cb);
 515         return 0;
 516 }
 517
 518 static int is_rerere_enabled(void)
 519 {
 520         const char *rr_cache;
 521         int rr_cache_exists;
 522
 523         if (!rerere_enabled)
 524                 return 0;
 525
 526         rr_cache = git_path("rr-cache");
 527         rr_cache_exists = is_directory(rr_cache);
 528         if (rerere_enabled < 0)
 529                 return rr_cache_exists;
 530
 531         if (!rr_cache_exists &&
 532             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 533                 die("Could not create directory %s", rr_cache);
 534         return 1;
 535 }
 536
 537 int setup_rerere(struct string_list *merge_rr, int flags)
 538 {
 539         int fd;
 540
 541         git_config(git_rerere_config, NULL);
 542         if (!is_rerere_enabled())
 543                 return -1;
 544
 545         if (flags & (RERERE_AUTOUPDATE|RERERE_NOAUTOUPDATE))
 546                 rerere_autoupdate = !!(flags & RERERE_AUTOUPDATE);
 547         merge_rr_path = git_pathdup("MERGE_RR");
 548         fd = hold_lock_file_for_update(&write_lock, merge_rr_path,
 549                                        LOCK_DIE_ON_ERROR);
 550         read_rr(merge_rr);
 551         return fd;
 552 }
 553
 554 int rerere(int flags)
 555 {
 556         struct string_list merge_rr = { NULL, 0, 0, 1 };
 557         int fd;
 558
 559         fd = setup_rerere(&merge_rr, flags);
 560         if (fd < 0)
 561                 return 0;
 562         return do_plain_rerere(&merge_rr, fd);
 563 }
 564
 565 static int rerere_forget_one_path(const char *path, struct string_list *rr)
 566 {
 567         const char *filename;
 568         char *hex;
 569         unsigned char sha1[20];
 570         int ret;
 571
 572         ret = handle_cache(path, sha1, NULL);
 573         if (ret < 1)
 574                 return error("Could not parse conflict hunks in '%s'", path);
 575         hex = xstrdup(sha1_to_hex(sha1));
 576         filename = rerere_path(hex, "postimage");
 577         if (unlink(filename))
 578                 return (errno == ENOENT
 579                         ? error("no remembered resolution for %s", path)
 580                         : error("cannot unlink %s: %s", filename, strerror(errno)));
 581
 582         handle_cache(path, sha1, rerere_path(hex, "preimage"));
 583         fprintf(stderr, "Updated preimage for '%s'\n", path);
 584
 585
 586         string_list_insert(path, rr)->util = hex;
 587         fprintf(stderr, "Forgot resolution for %s\n", path);
 588         return 0;
 589 }
 590
 591 int rerere_forget(const char **pathspec)
 592 {
 593         int i, fd;
 594         struct string_list conflict = { NULL, 0, 0, 1 };
 595         struct string_list merge_rr = { NULL, 0, 0, 1 };
 596
 597         if (read_cache() < 0)
 598                 return error("Could not read index");
 599
 600         fd = setup_rerere(&merge_rr, RERERE_NOAUTOUPDATE);
 601
 602         unmerge_cache(pathspec);
 603         find_conflict(&conflict);
 604         for (i = 0; i < conflict.nr; i++) {
 605                 struct string_list_item *it = &conflict.items[i];
 606                 if (!match_pathspec(pathspec, it->string, strlen(it->string),
 607                                     0, NULL))
 608                         continue;
 609                 rerere_forget_one_path(it->string, &merge_rr);
 610         }
 611         return write_rr(&merge_rr, fd);
 612 }