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