rerere.c

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