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 (close(out_fd) != 0)
  65                 die("unable to write rerere record");
  66         return commit_lock_file(&write_lock);
  67 }
  68
  69 struct buffer {
  70         char *ptr;
  71         int nr, alloc;
  72 };
  73
  74 static void append_line(struct buffer *buffer, const char *line)
  75 {
  76         int len = strlen(line);
  77
  78         if (buffer->nr + len > buffer->alloc) {
  79                 buffer->alloc = alloc_nr(buffer->nr + len);
  80                 buffer->ptr = xrealloc(buffer->ptr, buffer->alloc);
  81         }
  82         memcpy(buffer->ptr + buffer->nr, line, len);
  83         buffer->nr += len;
  84 }
  85
  86 static void clear_buffer(struct buffer *buffer)
  87 {
  88         free(buffer->ptr);
  89         buffer->ptr = NULL;
  90         buffer->nr = buffer->alloc = 0;
  91 }
  92
  93 static int handle_file(const char *path,
  94          unsigned char *sha1, const char *output)
  95 {
  96         SHA_CTX ctx;
  97         char buf[1024];
  98         int hunk = 0, hunk_no = 0;
  99         struct buffer minus = { NULL, 0, 0 }, plus = { NULL, 0, 0 };
 100         struct buffer *one = &minus, *two = &plus;
 101         FILE *f = fopen(path, "r");
 102         FILE *out;
 103
 104         if (!f)
 105                 return error("Could not open %s", path);
 106
 107         if (output) {
 108                 out = fopen(output, "w");
 109                 if (!out) {
 110                         fclose(f);
 111                         return error("Could not write %s", output);
 112                 }
 113         } else
 114                 out = NULL;
 115
 116         if (sha1)
 117                 SHA1_Init(&ctx);
 118
 119         while (fgets(buf, sizeof(buf), f)) {
 120                 if (!prefixcmp(buf, "<<<<<<< "))
 121                         hunk = 1;
 122                 else if (!prefixcmp(buf, "======="))
 123                         hunk = 2;
 124                 else if (!prefixcmp(buf, ">>>>>>> ")) {
 125                         int one_is_longer = (one->nr > two->nr);
 126                         int common_len = one_is_longer ? two->nr : one->nr;
 127                         int cmp = memcmp(one->ptr, two->ptr, common_len);
 128
 129                         hunk_no++;
 130                         hunk = 0;
 131                         if ((cmp > 0) || ((cmp == 0) && one_is_longer)) {
 132                                 struct buffer *swap = one;
 133                                 one = two;
 134                                 two = swap;
 135                         }
 136                         if (out) {
 137                                 fputs("<<<<<<<\n", out);
 138                                 fwrite(one->ptr, one->nr, 1, out);
 139                                 fputs("=======\n", out);
 140                                 fwrite(two->ptr, two->nr, 1, out);
 141                                 fputs(">>>>>>>\n", out);
 142                         }
 143                         if (sha1) {
 144                                 SHA1_Update(&ctx, one->ptr, one->nr);
 145                                 SHA1_Update(&ctx, "\0", 1);
 146                                 SHA1_Update(&ctx, two->ptr, two->nr);
 147                                 SHA1_Update(&ctx, "\0", 1);
 148                         }
 149                         clear_buffer(one);
 150                         clear_buffer(two);
 151                 } else if (hunk == 1)
 152                         append_line(one, buf);
 153                 else if (hunk == 2)
 154                         append_line(two, buf);
 155                 else if (out)
 156                         fputs(buf, out);
 157         }
 158
 159         fclose(f);
 160         if (out)
 161                 fclose(out);
 162         if (sha1)
 163                 SHA1_Final(sha1, &ctx);
 164         return hunk_no;
 165 }
 166
 167 static int find_conflict(struct path_list *conflict)
 168 {
 169         int i;
 170         if (read_cache() < 0)
 171                 return error("Could not read index");
 172         for (i = 0; i+1 < active_nr; i++) {
 173                 struct cache_entry *e2 = active_cache[i];
 174                 struct cache_entry *e3 = active_cache[i+1];
 175                 if (ce_stage(e2) == 2 &&
 176                     ce_stage(e3) == 3 &&
 177                     ce_same_name(e2, e3) &&
 178                     S_ISREG(ntohl(e2->ce_mode)) &&
 179                     S_ISREG(ntohl(e3->ce_mode))) {
 180                         path_list_insert((const char *)e2->name, conflict);
 181                         i++; /* skip over both #2 and #3 */
 182                 }
 183         }
 184         return 0;
 185 }
 186
 187 static int merge(const char *name, const char *path)
 188 {
 189         int ret;
 190         mmfile_t cur, base, other;
 191         mmbuffer_t result = {NULL, 0};
 192         xpparam_t xpp = {XDF_NEED_MINIMAL};
 193
 194         if (handle_file(path, NULL, rr_path(name, "thisimage")) < 0)
 195                 return 1;
 196
 197         if (read_mmfile(&cur, rr_path(name, "thisimage")) ||
 198                         read_mmfile(&base, rr_path(name, "preimage")) ||
 199                         read_mmfile(&other, rr_path(name, "postimage")))
 200                 return 1;
 201         ret = xdl_merge(&base, &cur, "", &other, "",
 202                         &xpp, XDL_MERGE_ZEALOUS, &result);
 203         if (!ret) {
 204                 FILE *f = fopen(path, "w");
 205                 if (!f)
 206                         return error("Could not write to %s", path);
 207                 fwrite(result.ptr, result.size, 1, f);
 208                 fclose(f);
 209         }
 210
 211         free(cur.ptr);
 212         free(base.ptr);
 213         free(other.ptr);
 214         free(result.ptr);
 215
 216         return ret;
 217 }
 218
 219 static void unlink_rr_item(const char *name)
 220 {
 221         unlink(rr_path(name, "thisimage"));
 222         unlink(rr_path(name, "preimage"));
 223         unlink(rr_path(name, "postimage"));
 224         rmdir(git_path("rr-cache/%s", name));
 225 }
 226
 227 static void garbage_collect(struct path_list *rr)
 228 {
 229         struct path_list to_remove = { NULL, 0, 0, 1 };
 230         char buf[1024];
 231         DIR *dir;
 232         struct dirent *e;
 233         int len, i, cutoff;
 234         time_t now = time(NULL), then;
 235
 236         strlcpy(buf, git_path("rr-cache"), sizeof(buf));
 237         len = strlen(buf);
 238         dir = opendir(buf);
 239         strcpy(buf + len++, "/");
 240         while ((e = readdir(dir))) {
 241                 const char *name = e->d_name;
 242                 struct stat st;
 243                 if (name[0] == '.' && (name[1] == '\0' ||
 244                                         (name[1] == '.' && name[2] == '\0')))
 245                         continue;
 246                 i = snprintf(buf + len, sizeof(buf) - len, "%s", name);
 247                 strlcpy(buf + len + i, "/preimage", sizeof(buf) - len - i);
 248                 if (stat(buf, &st))
 249                         continue;
 250                 then = st.st_mtime;
 251                 strlcpy(buf + len + i, "/postimage", sizeof(buf) - len - i);
 252                 cutoff = stat(buf, &st) ? cutoff_noresolve : cutoff_resolve;
 253                 if (then < now - cutoff * 86400) {
 254                         buf[len + i] = '\0';
 255                         path_list_insert(xstrdup(name), &to_remove);
 256                 }
 257         }
 258         for (i = 0; i < to_remove.nr; i++)
 259                 unlink_rr_item(to_remove.items[i].path);
 260         path_list_clear(&to_remove, 0);
 261 }
 262
 263 static int outf(void *dummy, mmbuffer_t *ptr, int nbuf)
 264 {
 265         int i;
 266         for (i = 0; i < nbuf; i++)
 267                 if (write_in_full(1, ptr[i].ptr, ptr[i].size) != ptr[i].size)
 268                         return -1;
 269         return 0;
 270 }
 271
 272 static int diff_two(const char *file1, const char *label1,
 273                 const char *file2, const char *label2)
 274 {
 275         xpparam_t xpp;
 276         xdemitconf_t xecfg;
 277         xdemitcb_t ecb;
 278         mmfile_t minus, plus;
 279
 280         if (read_mmfile(&minus, file1) || read_mmfile(&plus, file2))
 281                 return 1;
 282
 283         printf("--- a/%s\n+++ b/%s\n", label1, label2);
 284         fflush(stdout);
 285         xpp.flags = XDF_NEED_MINIMAL;
 286         memset(&xecfg, 0, sizeof(xecfg));
 287         xecfg.ctxlen = 3;
 288         ecb.outf = outf;
 289         xdl_diff(&minus, &plus, &xpp, &xecfg, &ecb);
 290
 291         free(minus.ptr);
 292         free(plus.ptr);
 293         return 0;
 294 }
 295
 296 static int copy_file(const char *src, const char *dest)
 297 {
 298         FILE *in, *out;
 299         char buffer[32768];
 300         int count;
 301
 302         if (!(in = fopen(src, "r")))
 303                 return error("Could not open %s", src);
 304         if (!(out = fopen(dest, "w")))
 305                 return error("Could not open %s", dest);
 306         while ((count = fread(buffer, 1, sizeof(buffer), in)))
 307                 fwrite(buffer, 1, count, out);
 308         fclose(in);
 309         fclose(out);
 310         return 0;
 311 }
 312
 313 static int do_plain_rerere(struct path_list *rr, int fd)
 314 {
 315         struct path_list conflict = { NULL, 0, 0, 1 };
 316         int i;
 317
 318         find_conflict(&conflict);
 319
 320         /*
 321          * MERGE_RR records paths with conflicts immediately after merge
 322          * failed.  Some of the conflicted paths might have been hand resolved
 323          * in the working tree since then, but the initial run would catch all
 324          * and register their preimages.
 325          */
 326
 327         for (i = 0; i < conflict.nr; i++) {
 328                 const char *path = conflict.items[i].path;
 329                 if (!path_list_has_path(rr, path)) {
 330                         unsigned char sha1[20];
 331                         char *hex;
 332                         int ret;
 333                         ret = handle_file(path, sha1, NULL);
 334                         if (ret < 1)
 335                                 continue;
 336                         hex = xstrdup(sha1_to_hex(sha1));
 337                         path_list_insert(path, rr)->util = hex;
 338                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 339                                 continue;;
 340                         handle_file(path, NULL, rr_path(hex, "preimage"));
 341                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 342                 }
 343         }
 344
 345         /*
 346          * Now some of the paths that had conflicts earlier might have been
 347          * hand resolved.  Others may be similar to a conflict already that
 348          * was resolved before.
 349          */
 350
 351         for (i = 0; i < rr->nr; i++) {
 352                 struct stat st;
 353                 int ret;
 354                 const char *path = rr->items[i].path;
 355                 const char *name = (const char *)rr->items[i].util;
 356
 357                 if (!stat(rr_path(name, "preimage"), &st) &&
 358                                 !stat(rr_path(name, "postimage"), &st)) {
 359                         if (!merge(name, path)) {
 360                                 fprintf(stderr, "Resolved '%s' using "
 361                                                 "previous resolution.\n", path);
 362                                 goto tail_optimization;
 363                         }
 364                 }
 365
 366                 /* Let's see if we have resolved it. */
 367                 ret = handle_file(path, NULL, NULL);
 368                 if (ret)
 369                         continue;
 370
 371                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 372                 copy_file(path, rr_path(name, "postimage"));
 373 tail_optimization:
 374                 if (i < rr->nr - 1)
 375                         memmove(rr->items + i,
 376                                 rr->items + i + 1,
 377                                 sizeof(rr->items[0]) * (rr->nr - i - 1));
 378                 rr->nr--;
 379                 i--;
 380         }
 381
 382         return write_rr(rr, fd);
 383 }
 384
 385 static int git_rerere_config(const char *var, const char *value)
 386 {
 387         if (!strcmp(var, "gc.rerereresolved"))
 388                 cutoff_resolve = git_config_int(var, value);
 389         else if (!strcmp(var, "gc.rerereunresolved"))
 390                 cutoff_noresolve = git_config_int(var, value);
 391         else if (!strcmp(var, "rerere.enabled"))
 392                 rerere_enabled = git_config_bool(var, value);
 393         else
 394                 return git_default_config(var, value);
 395         return 0;
 396 }
 397
 398 static int is_rerere_enabled(void)
 399 {
 400         struct stat st;
 401         const char *rr_cache;
 402         int rr_cache_exists;
 403
 404         if (!rerere_enabled)
 405                 return 0;
 406
 407         rr_cache = git_path("rr-cache");
 408         rr_cache_exists = !stat(rr_cache, &st) && S_ISDIR(st.st_mode);
 409         if (rerere_enabled < 0)
 410                 return rr_cache_exists;
 411
 412         if (!rr_cache_exists &&
 413             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 414                 die("Could not create directory %s", rr_cache);
 415         return 1;
 416 }
 417
 418 int cmd_rerere(int argc, const char **argv, const char *prefix)
 419 {
 420         struct path_list merge_rr = { NULL, 0, 0, 1 };
 421         int i, fd = -1;
 422
 423         git_config(git_rerere_config);
 424         if (!is_rerere_enabled())
 425                 return 0;
 426
 427         merge_rr_path = xstrdup(git_path("rr-cache/MERGE_RR"));
 428         fd = hold_lock_file_for_update(&write_lock, merge_rr_path, 1);
 429         read_rr(&merge_rr);
 430
 431         if (argc < 2)
 432                 return do_plain_rerere(&merge_rr, fd);
 433         else if (!strcmp(argv[1], "clear")) {
 434                 for (i = 0; i < merge_rr.nr; i++) {
 435                         struct stat st;
 436                         const char *name = (const char *)merge_rr.items[i].util;
 437                         if (!stat(git_path("rr-cache/%s", name), &st) &&
 438                                         S_ISDIR(st.st_mode) &&
 439                                         stat(rr_path(name, "postimage"), &st))
 440                                 unlink_rr_item(name);
 441                 }
 442                 unlink(merge_rr_path);
 443         } else if (!strcmp(argv[1], "gc"))
 444                 garbage_collect(&merge_rr);
 445         else if (!strcmp(argv[1], "status"))
 446                 for (i = 0; i < merge_rr.nr; i++)
 447                         printf("%s\n", merge_rr.items[i].path);
 448         else if (!strcmp(argv[1], "diff"))
 449                 for (i = 0; i < merge_rr.nr; i++) {
 450                         const char *path = merge_rr.items[i].path;
 451                         const char *name = (const char *)merge_rr.items[i].util;
 452                         diff_two(rr_path(name, "preimage"), path, path, path);
 453                 }
 454         else
 455                 usage(git_rerere_usage);
 456
 457         path_list_clear(&merge_rr, 1);
 458         return 0;
 459 }