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