builtin-rerere.c

   1 #include "builtin.h"
   2 #include "cache.h"
   3 #include "path-list.h"
   4 #include "xdiff/xdiff.h"
   5 #include "xdiff-interface.h"
   6
   7 #include <time.h>
   8
   9 static const char git_rerere_usage[] =
  10 "git-rerere [clear | status | diff | gc]";
  11
  12 /* these values are days */
  13 static int cutoff_noresolve = 15;
  14 static int cutoff_resolve = 60;
  15
  16 /* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
  17 static int rerere_enabled = -1;
  18
  19 /* automatically update cleanly resolved paths to the index */
  20 static int rerere_autoupdate;
  21
  22 static char *merge_rr_path;
  23
  24 static const char *rr_path(const char *name, const char *file)
  25 {
  26         return git_path("rr-cache/%s/%s", name, file);
  27 }
  28
  29 static time_t rerere_created_at(const char *name)
  30 {
  31         struct stat st;
  32         return stat(rr_path(name, "preimage"), &st) ? (time_t) 0 : st.st_mtime;
  33 }
  34
  35 static int has_resolution(const char *name)
  36 {
  37         struct stat st;
  38         return !stat(rr_path(name, "postimage"), &st);
  39 }
  40
  41 static void read_rr(struct path_list *rr)
  42 {
  43         unsigned char sha1[20];
  44         char buf[PATH_MAX];
  45         FILE *in = fopen(merge_rr_path, "r");
  46         if (!in)
  47                 return;
  48         while (fread(buf, 40, 1, in) == 1) {
  49                 int i;
  50                 char *name;
  51                 if (get_sha1_hex(buf, sha1))
  52                         die("corrupt MERGE_RR");
  53                 buf[40] = '\0';
  54                 name = xstrdup(buf);
  55                 if (fgetc(in) != '\t')
  56                         die("corrupt MERGE_RR");
  57                 for (i = 0; i < sizeof(buf) && (buf[i] = fgetc(in)); i++)
  58                         ; /* do nothing */
  59                 if (i == sizeof(buf))
  60                         die("filename too long");
  61                 path_list_insert(buf, rr)->util = name;
  62         }
  63         fclose(in);
  64 }
  65
  66 static struct lock_file write_lock;
  67
  68 static int write_rr(struct path_list *rr, int out_fd)
  69 {
  70         int i;
  71         for (i = 0; i < rr->nr; i++) {
  72                 const char *path;
  73                 int length;
  74                 if (!rr->items[i].util)
  75                         continue;
  76                 path = rr->items[i].path;
  77                 length = strlen(path) + 1;
  78                 if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
  79                     write_in_full(out_fd, "\t", 1) != 1 ||
  80                     write_in_full(out_fd, path, length) != length)
  81                         die("unable to write rerere record");
  82         }
  83         if (commit_lock_file(&write_lock) != 0)
  84                 die("unable to write rerere record");
  85         return 0;
  86 }
  87
  88 static int handle_file(const char *path,
  89          unsigned char *sha1, const char *output)
  90 {
  91         SHA_CTX ctx;
  92         char buf[1024];
  93         int hunk = 0, hunk_no = 0;
  94         struct strbuf one, two;
  95         FILE *f = fopen(path, "r");
  96         FILE *out = NULL;
  97
  98         if (!f)
  99                 return error("Could not open %s", path);
 100
 101         if (output) {
 102                 out = fopen(output, "w");
 103                 if (!out) {
 104                         fclose(f);
 105                         return error("Could not write %s", output);
 106                 }
 107         }
 108
 109         if (sha1)
 110                 SHA1_Init(&ctx);
 111
 112         strbuf_init(&one, 0);
 113         strbuf_init(&two,  0);
 114         while (fgets(buf, sizeof(buf), f)) {
 115                 if (!prefixcmp(buf, "<<<<<<< ")) {
 116                         if (hunk)
 117                                 goto bad;
 118                         hunk = 1;
 119                 } else if (!prefixcmp(buf, "=======") && isspace(buf[7])) {
 120                         if (hunk != 1)
 121                                 goto bad;
 122                         hunk = 2;
 123                 } else if (!prefixcmp(buf, ">>>>>>> ")) {
 124                         if (hunk != 2)
 125                                 goto bad;
 126                         if (strbuf_cmp(&one, &two) > 0)
 127                                 strbuf_swap(&one, &two);
 128                         hunk_no++;
 129                         hunk = 0;
 130                         if (out) {
 131                                 fputs("<<<<<<<\n", out);
 132                                 fwrite(one.buf, one.len, 1, out);
 133                                 fputs("=======\n", out);
 134                                 fwrite(two.buf, two.len, 1, out);
 135                                 fputs(">>>>>>>\n", out);
 136                         }
 137                         if (sha1) {
 138                                 SHA1_Update(&ctx, one.buf ? one.buf : "",
 139                                             one.len + 1);
 140                                 SHA1_Update(&ctx, two.buf ? two.buf : "",
 141                                             two.len + 1);
 142                         }
 143                         strbuf_reset(&one);
 144                         strbuf_reset(&two);
 145                 } else if (hunk == 1)
 146                         strbuf_addstr(&one, buf);
 147                 else if (hunk == 2)
 148                         strbuf_addstr(&two, buf);
 149                 else if (out)
 150                         fputs(buf, out);
 151                 continue;
 152         bad:
 153                 hunk = 99; /* force error exit */
 154                 break;
 155         }
 156         strbuf_release(&one);
 157         strbuf_release(&two);
 158
 159         fclose(f);
 160         if (out)
 161                 fclose(out);
 162         if (sha1)
 163                 SHA1_Final(sha1, &ctx);
 164         if (hunk) {
 165                 if (output)
 166                         unlink(output);
 167                 return error("Could not parse conflict hunks in %s", path);
 168         }
 169         return hunk_no;
 170 }
 171
 172 static int find_conflict(struct path_list *conflict)
 173 {
 174         int i;
 175         if (read_cache() < 0)
 176                 return error("Could not read index");
 177         for (i = 0; i+1 < active_nr; i++) {
 178                 struct cache_entry *e2 = active_cache[i];
 179                 struct cache_entry *e3 = active_cache[i+1];
 180                 if (ce_stage(e2) == 2 &&
 181                     ce_stage(e3) == 3 &&
 182                     ce_same_name(e2, e3) &&
 183                     S_ISREG(e2->ce_mode) &&
 184                     S_ISREG(e3->ce_mode)) {
 185                         path_list_insert((const char *)e2->name, conflict);
 186                         i++; /* skip over both #2 and #3 */
 187                 }
 188         }
 189         return 0;
 190 }
 191
 192 static int merge(const char *name, const char *path)
 193 {
 194         int ret;
 195         mmfile_t cur, base, other;
 196         mmbuffer_t result = {NULL, 0};
 197         xpparam_t xpp = {XDF_NEED_MINIMAL};
 198
 199         if (handle_file(path, NULL, rr_path(name, "thisimage")) < 0)
 200                 return 1;
 201
 202         if (read_mmfile(&cur, rr_path(name, "thisimage")) ||
 203                         read_mmfile(&base, rr_path(name, "preimage")) ||
 204                         read_mmfile(&other, rr_path(name, "postimage")))
 205                 return 1;
 206         ret = xdl_merge(&base, &cur, "", &other, "",
 207                         &xpp, XDL_MERGE_ZEALOUS, &result);
 208         if (!ret) {
 209                 FILE *f = fopen(path, "w");
 210                 if (!f)
 211                         return error("Could not write to %s", path);
 212                 fwrite(result.ptr, result.size, 1, f);
 213                 fclose(f);
 214         }
 215
 216         free(cur.ptr);
 217         free(base.ptr);
 218         free(other.ptr);
 219         free(result.ptr);
 220
 221         return ret;
 222 }
 223
 224 static void unlink_rr_item(const char *name)
 225 {
 226         unlink(rr_path(name, "thisimage"));
 227         unlink(rr_path(name, "preimage"));
 228         unlink(rr_path(name, "postimage"));
 229         rmdir(git_path("rr-cache/%s", name));
 230 }
 231
 232 static void garbage_collect(struct path_list *rr)
 233 {
 234         struct path_list to_remove = { NULL, 0, 0, 1 };
 235         DIR *dir;
 236         struct dirent *e;
 237         int i, cutoff;
 238         time_t now = time(NULL), then;
 239
 240         dir = opendir(git_path("rr-cache"));
 241         while ((e = readdir(dir))) {
 242                 const char *name = e->d_name;
 243                 if (name[0] == '.' &&
 244                     (name[1] == '\0' || (name[1] == '.' && name[2] == '\0')))
 245                         continue;
 246                 then = rerere_created_at(name);
 247                 if (!then)
 248                         continue;
 249                 cutoff = (has_resolution(name)
 250                           ? cutoff_resolve : cutoff_noresolve);
 251                 if (then < now - cutoff * 86400)
 252                         path_list_append(name, &to_remove);
 253         }
 254         for (i = 0; i < to_remove.nr; i++)
 255                 unlink_rr_item(to_remove.items[i].path);
 256         path_list_clear(&to_remove, 0);
 257 }
 258
 259 static int outf(void *dummy, mmbuffer_t *ptr, int nbuf)
 260 {
 261         int i;
 262         for (i = 0; i < nbuf; i++)
 263                 if (write_in_full(1, ptr[i].ptr, ptr[i].size) != ptr[i].size)
 264                         return -1;
 265         return 0;
 266 }
 267
 268 static int diff_two(const char *file1, const char *label1,
 269                 const char *file2, const char *label2)
 270 {
 271         xpparam_t xpp;
 272         xdemitconf_t xecfg;
 273         xdemitcb_t ecb;
 274         mmfile_t minus, plus;
 275
 276         if (read_mmfile(&minus, file1) || read_mmfile(&plus, file2))
 277                 return 1;
 278
 279         printf("--- a/%s\n+++ b/%s\n", label1, label2);
 280         fflush(stdout);
 281         xpp.flags = XDF_NEED_MINIMAL;
 282         memset(&xecfg, 0, sizeof(xecfg));
 283         xecfg.ctxlen = 3;
 284         ecb.outf = outf;
 285         xdi_diff(&minus, &plus, &xpp, &xecfg, &ecb);
 286
 287         free(minus.ptr);
 288         free(plus.ptr);
 289         return 0;
 290 }
 291
 292 static struct lock_file index_lock;
 293
 294 static int update_paths(struct path_list *update)
 295 {
 296         int i;
 297         int fd = hold_locked_index(&index_lock, 0);
 298         int status = 0;
 299
 300         if (fd < 0)
 301                 return -1;
 302
 303         for (i = 0; i < update->nr; i++) {
 304                 struct path_list_item *item = &update->items[i];
 305                 if (add_file_to_cache(item->path, ADD_CACHE_IGNORE_ERRORS))
 306                         status = -1;
 307         }
 308
 309         if (!status && active_cache_changed) {
 310                 if (write_cache(fd, active_cache, active_nr) ||
 311                     commit_locked_index(&index_lock))
 312                         die("Unable to write new index file");
 313         } else if (fd >= 0)
 314                 rollback_lock_file(&index_lock);
 315         return status;
 316 }
 317
 318 static int do_plain_rerere(struct path_list *rr, int fd)
 319 {
 320         struct path_list conflict = { NULL, 0, 0, 1 };
 321         struct path_list update = { NULL, 0, 0, 1 };
 322         int i;
 323
 324         find_conflict(&conflict);
 325
 326         /*
 327          * MERGE_RR records paths with conflicts immediately after merge
 328          * failed.  Some of the conflicted paths might have been hand resolved
 329          * in the working tree since then, but the initial run would catch all
 330          * and register their preimages.
 331          */
 332
 333         for (i = 0; i < conflict.nr; i++) {
 334                 const char *path = conflict.items[i].path;
 335                 if (!path_list_has_path(rr, path)) {
 336                         unsigned char sha1[20];
 337                         char *hex;
 338                         int ret;
 339                         ret = handle_file(path, sha1, NULL);
 340                         if (ret < 1)
 341                                 continue;
 342                         hex = xstrdup(sha1_to_hex(sha1));
 343                         path_list_insert(path, rr)->util = hex;
 344                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 345                                 continue;;
 346                         handle_file(path, NULL, rr_path(hex, "preimage"));
 347                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 348                 }
 349         }
 350
 351         /*
 352          * Now some of the paths that had conflicts earlier might have been
 353          * hand resolved.  Others may be similar to a conflict already that
 354          * was resolved before.
 355          */
 356
 357         for (i = 0; i < rr->nr; i++) {
 358                 int ret;
 359                 const char *path = rr->items[i].path;
 360                 const char *name = (const char *)rr->items[i].util;
 361
 362                 if (has_resolution(name)) {
 363                         if (!merge(name, path)) {
 364                                 fprintf(stderr, "Resolved '%s' using "
 365                                                 "previous resolution.\n", path);
 366                                 if (rerere_autoupdate)
 367                                         path_list_insert(path, &update);
 368                                 goto mark_resolved;
 369                         }
 370                 }
 371
 372                 /* Let's see if we have resolved it. */
 373                 ret = handle_file(path, NULL, NULL);
 374                 if (ret)
 375                         continue;
 376
 377                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 378                 copy_file(rr_path(name, "postimage"), path, 0666);
 379         mark_resolved:
 380                 rr->items[i].util = NULL;
 381         }
 382
 383         if (update.nr)
 384                 update_paths(&update);
 385
 386         return write_rr(rr, fd);
 387 }
 388
 389 static int git_rerere_config(const char *var, const char *value, void *cb)
 390 {
 391         if (!strcmp(var, "gc.rerereresolved"))
 392                 cutoff_resolve = git_config_int(var, value);
 393         else if (!strcmp(var, "gc.rerereunresolved"))
 394                 cutoff_noresolve = git_config_int(var, value);
 395         else if (!strcmp(var, "rerere.enabled"))
 396                 rerere_enabled = git_config_bool(var, value);
 397         else if (!strcmp(var, "rerere.autoupdate"))
 398                 rerere_autoupdate = git_config_bool(var, value);
 399         else
 400                 return git_default_config(var, value, cb);
 401         return 0;
 402 }
 403
 404 static int is_rerere_enabled(void)
 405 {
 406         struct stat st;
 407         const char *rr_cache;
 408         int rr_cache_exists;
 409
 410         if (!rerere_enabled)
 411                 return 0;
 412
 413         rr_cache = git_path("rr-cache");
 414         rr_cache_exists = !stat(rr_cache, &st) && S_ISDIR(st.st_mode);
 415         if (rerere_enabled < 0)
 416                 return rr_cache_exists;
 417
 418         if (!rr_cache_exists &&
 419             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 420                 die("Could not create directory %s", rr_cache);
 421         return 1;
 422 }
 423
 424 static int setup_rerere(struct path_list *merge_rr)
 425 {
 426         int fd;
 427
 428         git_config(git_rerere_config, NULL);
 429         if (!is_rerere_enabled())
 430                 return -1;
 431
 432         merge_rr_path = xstrdup(git_path("rr-cache/MERGE_RR"));
 433         fd = hold_lock_file_for_update(&write_lock, merge_rr_path, 1);
 434         read_rr(merge_rr);
 435         return fd;
 436 }
 437
 438 int rerere(void)
 439 {
 440         struct path_list merge_rr = { NULL, 0, 0, 1 };
 441         int fd;
 442
 443         fd = setup_rerere(&merge_rr);
 444         if (fd < 0)
 445                 return 0;
 446         return do_plain_rerere(&merge_rr, fd);
 447 }
 448
 449 int cmd_rerere(int argc, const char **argv, const char *prefix)
 450 {
 451         struct path_list merge_rr = { NULL, 0, 0, 1 };
 452         int i, fd;
 453
 454         fd = setup_rerere(&merge_rr);
 455         if (fd < 0)
 456                 return 0;
 457
 458         if (argc < 2)
 459                 return do_plain_rerere(&merge_rr, fd);
 460         else if (!strcmp(argv[1], "clear")) {
 461                 for (i = 0; i < merge_rr.nr; i++) {
 462                         const char *name = (const char *)merge_rr.items[i].util;
 463                         if (!has_resolution(name))
 464                                 unlink_rr_item(name);
 465                 }
 466                 unlink(merge_rr_path);
 467         } else if (!strcmp(argv[1], "gc"))
 468                 garbage_collect(&merge_rr);
 469         else if (!strcmp(argv[1], "status"))
 470                 for (i = 0; i < merge_rr.nr; i++)
 471                         printf("%s\n", merge_rr.items[i].path);
 472         else if (!strcmp(argv[1], "diff"))
 473                 for (i = 0; i < merge_rr.nr; i++) {
 474                         const char *path = merge_rr.items[i].path;
 475                         const char *name = (const char *)merge_rr.items[i].util;
 476                         diff_two(rr_path(name, "preimage"), path, path, path);
 477                 }
 478         else
 479                 usage(git_rerere_usage);
 480
 481         path_list_clear(&merge_rr, 1);
 482         return 0;
 483 }