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                         hunk = 1;
 117                 else if (!prefixcmp(buf, "======="))
 118                         hunk = 2;
 119                 else if (!prefixcmp(buf, ">>>>>>> ")) {
 120                         if (strbuf_cmp(&one, &two) > 0)
 121                                 strbuf_swap(&one, &two);
 122                         hunk_no++;
 123                         hunk = 0;
 124                         if (out) {
 125                                 fputs("<<<<<<<\n", out);
 126                                 fwrite(one.buf, one.len, 1, out);
 127                                 fputs("=======\n", out);
 128                                 fwrite(two.buf, two.len, 1, out);
 129                                 fputs(">>>>>>>\n", out);
 130                         }
 131                         if (sha1) {
 132                                 SHA1_Update(&ctx, one.buf ? one.buf : "",
 133                                             one.len + 1);
 134                                 SHA1_Update(&ctx, two.buf ? two.buf : "",
 135                                             two.len + 1);
 136                         }
 137                         strbuf_reset(&one);
 138                         strbuf_reset(&two);
 139                 } else if (hunk == 1)
 140                         strbuf_addstr(&one, buf);
 141                 else if (hunk == 2)
 142                         strbuf_addstr(&two, buf);
 143                 else if (out)
 144                         fputs(buf, out);
 145         }
 146         strbuf_release(&one);
 147         strbuf_release(&two);
 148
 149         fclose(f);
 150         if (out)
 151                 fclose(out);
 152         if (sha1)
 153                 SHA1_Final(sha1, &ctx);
 154         if (hunk) {
 155                 if (output)
 156                         unlink(output);
 157                 return error("Could not parse conflict hunks in %s", path);
 158         }
 159         return hunk_no;
 160 }
 161
 162 static int find_conflict(struct path_list *conflict)
 163 {
 164         int i;
 165         if (read_cache() < 0)
 166                 return error("Could not read index");
 167         for (i = 0; i+1 < active_nr; i++) {
 168                 struct cache_entry *e2 = active_cache[i];
 169                 struct cache_entry *e3 = active_cache[i+1];
 170                 if (ce_stage(e2) == 2 &&
 171                     ce_stage(e3) == 3 &&
 172                     ce_same_name(e2, e3) &&
 173                     S_ISREG(e2->ce_mode) &&
 174                     S_ISREG(e3->ce_mode)) {
 175                         path_list_insert((const char *)e2->name, conflict);
 176                         i++; /* skip over both #2 and #3 */
 177                 }
 178         }
 179         return 0;
 180 }
 181
 182 static int merge(const char *name, const char *path)
 183 {
 184         int ret;
 185         mmfile_t cur, base, other;
 186         mmbuffer_t result = {NULL, 0};
 187         xpparam_t xpp = {XDF_NEED_MINIMAL};
 188
 189         if (handle_file(path, NULL, rr_path(name, "thisimage")) < 0)
 190                 return 1;
 191
 192         if (read_mmfile(&cur, rr_path(name, "thisimage")) ||
 193                         read_mmfile(&base, rr_path(name, "preimage")) ||
 194                         read_mmfile(&other, rr_path(name, "postimage")))
 195                 return 1;
 196         ret = xdl_merge(&base, &cur, "", &other, "",
 197                         &xpp, XDL_MERGE_ZEALOUS, &result);
 198         if (!ret) {
 199                 FILE *f = fopen(path, "w");
 200                 if (!f)
 201                         return error("Could not write to %s", path);
 202                 fwrite(result.ptr, result.size, 1, f);
 203                 fclose(f);
 204         }
 205
 206         free(cur.ptr);
 207         free(base.ptr);
 208         free(other.ptr);
 209         free(result.ptr);
 210
 211         return ret;
 212 }
 213
 214 static void unlink_rr_item(const char *name)
 215 {
 216         unlink(rr_path(name, "thisimage"));
 217         unlink(rr_path(name, "preimage"));
 218         unlink(rr_path(name, "postimage"));
 219         rmdir(git_path("rr-cache/%s", name));
 220 }
 221
 222 static void garbage_collect(struct path_list *rr)
 223 {
 224         struct path_list to_remove = { NULL, 0, 0, 1 };
 225         DIR *dir;
 226         struct dirent *e;
 227         int i, cutoff;
 228         time_t now = time(NULL), then;
 229
 230         dir = opendir(git_path("rr-cache"));
 231         while ((e = readdir(dir))) {
 232                 const char *name = e->d_name;
 233                 if (name[0] == '.' &&
 234                     (name[1] == '\0' || (name[1] == '.' && name[2] == '\0')))
 235                         continue;
 236                 then = rerere_created_at(name);
 237                 if (!then)
 238                         continue;
 239                 cutoff = (has_resolution(name)
 240                           ? cutoff_resolve : cutoff_noresolve);
 241                 if (then < now - cutoff * 86400)
 242                         path_list_append(name, &to_remove);
 243         }
 244         for (i = 0; i < to_remove.nr; i++)
 245                 unlink_rr_item(to_remove.items[i].path);
 246         path_list_clear(&to_remove, 0);
 247 }
 248
 249 static int outf(void *dummy, mmbuffer_t *ptr, int nbuf)
 250 {
 251         int i;
 252         for (i = 0; i < nbuf; i++)
 253                 if (write_in_full(1, ptr[i].ptr, ptr[i].size) != ptr[i].size)
 254                         return -1;
 255         return 0;
 256 }
 257
 258 static int diff_two(const char *file1, const char *label1,
 259                 const char *file2, const char *label2)
 260 {
 261         xpparam_t xpp;
 262         xdemitconf_t xecfg;
 263         xdemitcb_t ecb;
 264         mmfile_t minus, plus;
 265
 266         if (read_mmfile(&minus, file1) || read_mmfile(&plus, file2))
 267                 return 1;
 268
 269         printf("--- a/%s\n+++ b/%s\n", label1, label2);
 270         fflush(stdout);
 271         xpp.flags = XDF_NEED_MINIMAL;
 272         memset(&xecfg, 0, sizeof(xecfg));
 273         xecfg.ctxlen = 3;
 274         ecb.outf = outf;
 275         xdi_diff(&minus, &plus, &xpp, &xecfg, &ecb);
 276
 277         free(minus.ptr);
 278         free(plus.ptr);
 279         return 0;
 280 }
 281
 282 static struct lock_file index_lock;
 283
 284 static int update_paths(struct path_list *update)
 285 {
 286         int i;
 287         int fd = hold_locked_index(&index_lock, 0);
 288         int status = 0;
 289
 290         if (fd < 0)
 291                 return -1;
 292
 293         for (i = 0; i < update->nr; i++) {
 294                 struct path_list_item *item = &update->items[i];
 295                 if (add_file_to_cache(item->path, ADD_CACHE_IGNORE_ERRORS))
 296                         status = -1;
 297         }
 298
 299         if (!status && active_cache_changed) {
 300                 if (write_cache(fd, active_cache, active_nr) ||
 301                     commit_locked_index(&index_lock))
 302                         die("Unable to write new index file");
 303         } else if (fd >= 0)
 304                 rollback_lock_file(&index_lock);
 305         return status;
 306 }
 307
 308 static int do_plain_rerere(struct path_list *rr, int fd)
 309 {
 310         struct path_list conflict = { NULL, 0, 0, 1 };
 311         struct path_list update = { NULL, 0, 0, 1 };
 312         int i;
 313
 314         find_conflict(&conflict);
 315
 316         /*
 317          * MERGE_RR records paths with conflicts immediately after merge
 318          * failed.  Some of the conflicted paths might have been hand resolved
 319          * in the working tree since then, but the initial run would catch all
 320          * and register their preimages.
 321          */
 322
 323         for (i = 0; i < conflict.nr; i++) {
 324                 const char *path = conflict.items[i].path;
 325                 if (!path_list_has_path(rr, path)) {
 326                         unsigned char sha1[20];
 327                         char *hex;
 328                         int ret;
 329                         ret = handle_file(path, sha1, NULL);
 330                         if (ret < 1)
 331                                 continue;
 332                         hex = xstrdup(sha1_to_hex(sha1));
 333                         path_list_insert(path, rr)->util = hex;
 334                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 335                                 continue;;
 336                         handle_file(path, NULL, rr_path(hex, "preimage"));
 337                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 338                 }
 339         }
 340
 341         /*
 342          * Now some of the paths that had conflicts earlier might have been
 343          * hand resolved.  Others may be similar to a conflict already that
 344          * was resolved before.
 345          */
 346
 347         for (i = 0; i < rr->nr; i++) {
 348                 int ret;
 349                 const char *path = rr->items[i].path;
 350                 const char *name = (const char *)rr->items[i].util;
 351
 352                 if (has_resolution(name)) {
 353                         if (!merge(name, path)) {
 354                                 fprintf(stderr, "Resolved '%s' using "
 355                                                 "previous resolution.\n", path);
 356                                 if (rerere_autoupdate)
 357                                         path_list_insert(path, &update);
 358                                 goto mark_resolved;
 359                         }
 360                 }
 361
 362                 /* Let's see if we have resolved it. */
 363                 ret = handle_file(path, NULL, NULL);
 364                 if (ret)
 365                         continue;
 366
 367                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 368                 copy_file(rr_path(name, "postimage"), path, 0666);
 369         mark_resolved:
 370                 rr->items[i].util = NULL;
 371         }
 372
 373         if (update.nr)
 374                 update_paths(&update);
 375
 376         return write_rr(rr, fd);
 377 }
 378
 379 static int git_rerere_config(const char *var, const char *value, void *cb)
 380 {
 381         if (!strcmp(var, "gc.rerereresolved"))
 382                 cutoff_resolve = git_config_int(var, value);
 383         else if (!strcmp(var, "gc.rerereunresolved"))
 384                 cutoff_noresolve = git_config_int(var, value);
 385         else if (!strcmp(var, "rerere.enabled"))
 386                 rerere_enabled = git_config_bool(var, value);
 387         else if (!strcmp(var, "rerere.autoupdate"))
 388                 rerere_autoupdate = git_config_bool(var, value);
 389         else
 390                 return git_default_config(var, value, cb);
 391         return 0;
 392 }
 393
 394 static int is_rerere_enabled(void)
 395 {
 396         struct stat st;
 397         const char *rr_cache;
 398         int rr_cache_exists;
 399
 400         if (!rerere_enabled)
 401                 return 0;
 402
 403         rr_cache = git_path("rr-cache");
 404         rr_cache_exists = !stat(rr_cache, &st) && S_ISDIR(st.st_mode);
 405         if (rerere_enabled < 0)
 406                 return rr_cache_exists;
 407
 408         if (!rr_cache_exists &&
 409             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 410                 die("Could not create directory %s", rr_cache);
 411         return 1;
 412 }
 413
 414 static int setup_rerere(struct path_list *merge_rr)
 415 {
 416         int fd;
 417
 418         git_config(git_rerere_config, NULL);
 419         if (!is_rerere_enabled())
 420                 return -1;
 421
 422         merge_rr_path = xstrdup(git_path("rr-cache/MERGE_RR"));
 423         fd = hold_lock_file_for_update(&write_lock, merge_rr_path, 1);
 424         read_rr(merge_rr);
 425         return fd;
 426 }
 427
 428 int rerere(void)
 429 {
 430         struct path_list merge_rr = { NULL, 0, 0, 1 };
 431         int fd;
 432
 433         fd = setup_rerere(&merge_rr);
 434         if (fd < 0)
 435                 return 0;
 436         return do_plain_rerere(&merge_rr, fd);
 437 }
 438
 439 int cmd_rerere(int argc, const char **argv, const char *prefix)
 440 {
 441         struct path_list merge_rr = { NULL, 0, 0, 1 };
 442         int i, fd;
 443
 444         fd = setup_rerere(&merge_rr);
 445         if (fd < 0)
 446                 return 0;
 447
 448         if (argc < 2)
 449                 return do_plain_rerere(&merge_rr, fd);
 450         else if (!strcmp(argv[1], "clear")) {
 451                 for (i = 0; i < merge_rr.nr; i++) {
 452                         const char *name = (const char *)merge_rr.items[i].util;
 453                         if (!has_resolution(name))
 454                                 unlink_rr_item(name);
 455                 }
 456                 unlink(merge_rr_path);
 457         } else if (!strcmp(argv[1], "gc"))
 458                 garbage_collect(&merge_rr);
 459         else if (!strcmp(argv[1], "status"))
 460                 for (i = 0; i < merge_rr.nr; i++)
 461                         printf("%s\n", merge_rr.items[i].path);
 462         else if (!strcmp(argv[1], "diff"))
 463                 for (i = 0; i < merge_rr.nr; i++) {
 464                         const char *path = merge_rr.items[i].path;
 465                         const char *name = (const char *)merge_rr.items[i].util;
 466                         diff_two(rr_path(name, "preimage"), path, path, path);
 467                 }
 468         else
 469                 usage(git_rerere_usage);
 470
 471         path_list_clear(&merge_rr, 1);
 472         return 0;
 473 }