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