builtin-rerere.c

   1 #include "cache.h"
   2 #include "path-list.h"
   3 #include "xdiff/xdiff.h"
   4 #include "xdiff-interface.h"
   5
   6 #include <time.h>
   7
   8 static const char git_rerere_usage[] =
   9 "git-rerere [clear | status | diff | gc]";
  10
  11 /* these values are days */
  12 static int cutoff_noresolve = 15;
  13 static int cutoff_resolve = 60;
  14
  15 /* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
  16 static int rerere_enabled = -1;
  17
  18 static char *merge_rr_path;
  19
  20 static const char *rr_path(const char *name, const char *file)
  21 {
  22         return git_path("rr-cache/%s/%s", name, file);
  23 }
  24
  25 static void read_rr(struct path_list *rr)
  26 {
  27         unsigned char sha1[20];
  28         char buf[PATH_MAX];
  29         FILE *in = fopen(merge_rr_path, "r");
  30         if (!in)
  31                 return;
  32         while (fread(buf, 40, 1, in) == 1) {
  33                 int i;
  34                 char *name;
  35                 if (get_sha1_hex(buf, sha1))
  36                         die("corrupt MERGE_RR");
  37                 buf[40] = '\0';
  38                 name = xstrdup(buf);
  39                 if (fgetc(in) != '\t')
  40                         die("corrupt MERGE_RR");
  41                 for (i = 0; i < sizeof(buf) && (buf[i] = fgetc(in)); i++)
  42                         ; /* do nothing */
  43                 if (i == sizeof(buf))
  44                         die("filename too long");
  45                 path_list_insert(buf, rr)->util = xstrdup(name);
  46         }
  47         fclose(in);
  48 }
  49
  50 static struct lock_file write_lock;
  51
  52 static int write_rr(struct path_list *rr, int out_fd)
  53 {
  54         int i;
  55         for (i = 0; i < rr->nr; i++) {
  56                 const char *path = rr->items[i].path;
  57                 int length = strlen(path) + 1;
  58                 if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
  59                     write_in_full(out_fd, "\t", 1) != 1 ||
  60                     write_in_full(out_fd, path, length) != length)
  61                         die("unable to write rerere record");
  62         }
  63         if (close(out_fd) != 0)
  64                 die("unable to write rerere record");
  65         return commit_lock_file(&write_lock);
  66 }
  67
  68 struct buffer {
  69         char *ptr;
  70         int nr, alloc;
  71 };
  72
  73 static void append_line(struct buffer *buffer, const char *line)
  74 {
  75         int len = strlen(line);
  76
  77         if (buffer->nr + len > buffer->alloc) {
  78                 buffer->alloc = alloc_nr(buffer->nr + len);
  79                 buffer->ptr = xrealloc(buffer->ptr, buffer->alloc);
  80         }
  81         memcpy(buffer->ptr + buffer->nr, line, len);
  82         buffer->nr += len;
  83 }
  84
  85 static void clear_buffer(struct buffer *buffer)
  86 {
  87         free(buffer->ptr);
  88         buffer->ptr = NULL;
  89         buffer->nr = buffer->alloc = 0;
  90 }
  91
  92 static int handle_file(const char *path,
  93          unsigned char *sha1, const char *output)
  94 {
  95         SHA_CTX ctx;
  96         char buf[1024];
  97         int hunk = 0, hunk_no = 0;
  98         struct buffer minus = { NULL, 0, 0 }, plus = { NULL, 0, 0 };
  99         struct buffer *one = &minus, *two = &plus;
 100         FILE *f = fopen(path, "r");
 101         FILE *out;
 102
 103         if (!f)
 104                 return error("Could not open %s", path);
 105
 106         if (output) {
 107                 out = fopen(output, "w");
 108                 if (!out) {
 109                         fclose(f);
 110                         return error("Could not write %s", output);
 111                 }
 112         } else
 113                 out = NULL;
 114
 115         if (sha1)
 116                 SHA1_Init(&ctx);
 117
 118         while (fgets(buf, sizeof(buf), f)) {
 119                 if (!prefixcmp(buf, "<<<<<<< "))
 120                         hunk = 1;
 121                 else if (!prefixcmp(buf, "======="))
 122                         hunk = 2;
 123                 else if (!prefixcmp(buf, ">>>>>>> ")) {
 124                         int one_is_longer = (one->nr > two->nr);
 125                         int common_len = one_is_longer ? two->nr : one->nr;
 126                         int cmp = memcmp(one->ptr, two->ptr, common_len);
 127
 128                         hunk_no++;
 129                         hunk = 0;
 130                         if ((cmp > 0) || ((cmp == 0) && one_is_longer)) {
 131                                 struct buffer *swap = one;
 132                                 one = two;
 133                                 two = swap;
 134                         }
 135                         if (out) {
 136                                 fputs("<<<<<<<\n", out);
 137                                 fwrite(one->ptr, one->nr, 1, out);
 138                                 fputs("=======\n", out);
 139                                 fwrite(two->ptr, two->nr, 1, out);
 140                                 fputs(">>>>>>>\n", out);
 141                         }
 142                         if (sha1) {
 143                                 SHA1_Update(&ctx, one->ptr, one->nr);
 144                                 SHA1_Update(&ctx, "\0", 1);
 145                                 SHA1_Update(&ctx, two->ptr, two->nr);
 146                                 SHA1_Update(&ctx, "\0", 1);
 147                         }
 148                         clear_buffer(one);
 149                         clear_buffer(two);
 150                 } else if (hunk == 1)
 151                         append_line(one, buf);
 152                 else if (hunk == 2)
 153                         append_line(two, buf);
 154                 else if (out)
 155                         fputs(buf, out);
 156         }
 157
 158         fclose(f);
 159         if (out)
 160                 fclose(out);
 161         if (sha1)
 162                 SHA1_Final(sha1, &ctx);
 163         return hunk_no;
 164 }
 165
 166 static int find_conflict(struct path_list *conflict)
 167 {
 168         int i;
 169         if (read_cache() < 0)
 170                 return error("Could not read index");
 171         for (i = 0; i + 2 < active_nr; i++) {
 172                 struct cache_entry *e1 = active_cache[i];
 173                 struct cache_entry *e2 = active_cache[i+1];
 174                 struct cache_entry *e3 = active_cache[i+2];
 175                 if (ce_stage(e1) == 1 &&
 176                     ce_stage(e2) == 2 &&
 177                     ce_stage(e3) == 3 &&
 178                     ce_same_name(e1, e2) && ce_same_name(e1, e3) &&
 179                     S_ISREG(ntohl(e1->ce_mode)) &&
 180                     S_ISREG(ntohl(e2->ce_mode)) &&
 181                     S_ISREG(ntohl(e3->ce_mode))) {
 182                         path_list_insert((const char *)e1->name, conflict);
 183                         i += 2;
 184                 }
 185         }
 186         return 0;
 187 }
 188
 189 static int merge(const char *name, const char *path)
 190 {
 191         int ret;
 192         mmfile_t cur, base, other;
 193         mmbuffer_t result = {NULL, 0};
 194         xpparam_t xpp = {XDF_NEED_MINIMAL};
 195
 196         if (handle_file(path, NULL, rr_path(name, "thisimage")) < 0)
 197                 return 1;
 198
 199         if (read_mmfile(&cur, rr_path(name, "thisimage")) ||
 200                         read_mmfile(&base, rr_path(name, "preimage")) ||
 201                         read_mmfile(&other, rr_path(name, "postimage")))
 202                 return 1;
 203         ret = xdl_merge(&base, &cur, "", &other, "",
 204                         &xpp, XDL_MERGE_ZEALOUS, &result);
 205         if (!ret) {
 206                 FILE *f = fopen(path, "w");
 207                 if (!f)
 208                         return error("Could not write to %s", path);
 209                 fwrite(result.ptr, result.size, 1, f);
 210                 fclose(f);
 211         }
 212
 213         free(cur.ptr);
 214         free(base.ptr);
 215         free(other.ptr);
 216         free(result.ptr);
 217
 218         return ret;
 219 }
 220
 221 static void unlink_rr_item(const char *name)
 222 {
 223         unlink(rr_path(name, "thisimage"));
 224         unlink(rr_path(name, "preimage"));
 225         unlink(rr_path(name, "postimage"));
 226         rmdir(git_path("rr-cache/%s", name));
 227 }
 228
 229 static void garbage_collect(struct path_list *rr)
 230 {
 231         struct path_list to_remove = { NULL, 0, 0, 1 };
 232         char buf[1024];
 233         DIR *dir;
 234         struct dirent *e;
 235         int len, i, cutoff;
 236         time_t now = time(NULL), then;
 237
 238         strlcpy(buf, git_path("rr-cache"), sizeof(buf));
 239         len = strlen(buf);
 240         dir = opendir(buf);
 241         strcpy(buf + len++, "/");
 242         while ((e = readdir(dir))) {
 243                 const char *name = e->d_name;
 244                 struct stat st;
 245                 if (name[0] == '.' && (name[1] == '\0' ||
 246                                         (name[1] == '.' && name[2] == '\0')))
 247                         continue;
 248                 i = snprintf(buf + len, sizeof(buf) - len, "%s", name);
 249                 strlcpy(buf + len + i, "/preimage", sizeof(buf) - len - i);
 250                 if (stat(buf, &st))
 251                         continue;
 252                 then = st.st_mtime;
 253                 strlcpy(buf + len + i, "/postimage", sizeof(buf) - len - i);
 254                 cutoff = stat(buf, &st) ? cutoff_noresolve : cutoff_resolve;
 255                 if (then < now - cutoff * 86400) {
 256                         buf[len + i] = '\0';
 257                         path_list_insert(xstrdup(name), &to_remove);
 258                 }
 259         }
 260         for (i = 0; i < to_remove.nr; i++)
 261                 unlink_rr_item(to_remove.items[i].path);
 262         path_list_clear(&to_remove, 0);
 263 }
 264
 265 static int outf(void *dummy, mmbuffer_t *ptr, int nbuf)
 266 {
 267         int i;
 268         for (i = 0; i < nbuf; i++)
 269                 if (write_in_full(1, ptr[i].ptr, ptr[i].size) != ptr[i].size)
 270                         return -1;
 271         return 0;
 272 }
 273
 274 static int diff_two(const char *file1, const char *label1,
 275                 const char *file2, const char *label2)
 276 {
 277         xpparam_t xpp;
 278         xdemitconf_t xecfg;
 279         xdemitcb_t ecb;
 280         mmfile_t minus, plus;
 281
 282         if (read_mmfile(&minus, file1) || read_mmfile(&plus, file2))
 283                 return 1;
 284
 285         printf("--- a/%s\n+++ b/%s\n", label1, label2);
 286         fflush(stdout);
 287         xpp.flags = XDF_NEED_MINIMAL;
 288         memset(&xecfg, 0, sizeof(xecfg));
 289         xecfg.ctxlen = 3;
 290         ecb.outf = outf;
 291         xdl_diff(&minus, &plus, &xpp, &xecfg, &ecb);
 292
 293         free(minus.ptr);
 294         free(plus.ptr);
 295         return 0;
 296 }
 297
 298 static int copy_file(const char *src, const char *dest)
 299 {
 300         FILE *in, *out;
 301         char buffer[32768];
 302         int count;
 303
 304         if (!(in = fopen(src, "r")))
 305                 return error("Could not open %s", src);
 306         if (!(out = fopen(dest, "w")))
 307                 return error("Could not open %s", dest);
 308         while ((count = fread(buffer, 1, sizeof(buffer), in)))
 309                 fwrite(buffer, 1, count, out);
 310         fclose(in);
 311         fclose(out);
 312         return 0;
 313 }
 314
 315 static int do_plain_rerere(struct path_list *rr, int fd)
 316 {
 317         struct path_list conflict = { NULL, 0, 0, 1 };
 318         int i;
 319
 320         find_conflict(&conflict);
 321
 322         /*
 323          * MERGE_RR records paths with conflicts immediately after merge
 324          * failed.  Some of the conflicted paths might have been hand resolved
 325          * in the working tree since then, but the initial run would catch all
 326          * and register their preimages.
 327          */
 328
 329         for (i = 0; i < conflict.nr; i++) {
 330                 const char *path = conflict.items[i].path;
 331                 if (!path_list_has_path(rr, path)) {
 332                         unsigned char sha1[20];
 333                         char *hex;
 334                         int ret;
 335                         ret = handle_file(path, sha1, NULL);
 336                         if (ret < 1)
 337                                 continue;
 338                         hex = xstrdup(sha1_to_hex(sha1));
 339                         path_list_insert(path, rr)->util = hex;
 340                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 341                                 continue;;
 342                         handle_file(path, NULL, rr_path(hex, "preimage"));
 343                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 344                 }
 345         }
 346
 347         /*
 348          * Now some of the paths that had conflicts earlier might have been
 349          * hand resolved.  Others may be similar to a conflict already that
 350          * was resolved before.
 351          */
 352
 353         for (i = 0; i < rr->nr; i++) {
 354                 struct stat st;
 355                 int ret;
 356                 const char *path = rr->items[i].path;
 357                 const char *name = (const char *)rr->items[i].util;
 358
 359                 if (!stat(rr_path(name, "preimage"), &st) &&
 360                                 !stat(rr_path(name, "postimage"), &st)) {
 361                         if (!merge(name, path)) {
 362                                 fprintf(stderr, "Resolved '%s' using "
 363                                                 "previous resolution.\n", path);
 364                                 goto tail_optimization;
 365                         }
 366                 }
 367
 368                 /* Let's see if we have resolved it. */
 369                 ret = handle_file(path, NULL, NULL);
 370                 if (ret)
 371                         continue;
 372
 373                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 374                 copy_file(path, rr_path(name, "postimage"));
 375 tail_optimization:
 376                 if (i < rr->nr - 1)
 377                         memmove(rr->items + i,
 378                                 rr->items + i + 1,
 379                                 sizeof(rr->items[0]) * (rr->nr - i - 1));
 380                 rr->nr--;
 381                 i--;
 382         }
 383
 384         return write_rr(rr, fd);
 385 }
 386
 387 static int git_rerere_config(const char *var, const char *value)
 388 {
 389         if (!strcmp(var, "gc.rerereresolved"))
 390                 cutoff_resolve = git_config_int(var, value);
 391         else if (!strcmp(var, "gc.rerereunresolved"))
 392                 cutoff_noresolve = git_config_int(var, value);
 393         else if (!strcmp(var, "rerere.enabled"))
 394                 rerere_enabled = git_config_bool(var, value);
 395         else
 396                 return git_default_config(var, value);
 397         return 0;
 398 }
 399
 400 static int is_rerere_enabled(void)
 401 {
 402         struct stat st;
 403         const char *rr_cache;
 404         int rr_cache_exists;
 405
 406         if (!rerere_enabled)
 407                 return 0;
 408
 409         rr_cache = git_path("rr-cache");
 410         rr_cache_exists = !stat(rr_cache, &st) && S_ISDIR(st.st_mode);
 411         if (rerere_enabled < 0)
 412                 return rr_cache_exists;
 413
 414         if (!rr_cache_exists &&
 415             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 416                 die("Could not create directory %s", rr_cache);
 417         return 1;
 418 }
 419
 420 int cmd_rerere(int argc, const char **argv, const char *prefix)
 421 {
 422         struct path_list merge_rr = { NULL, 0, 0, 1 };
 423         int i, fd = -1;
 424
 425         git_config(git_rerere_config);
 426         if (!is_rerere_enabled())
 427                 return 0;
 428
 429         merge_rr_path = xstrdup(git_path("rr-cache/MERGE_RR"));
 430         fd = hold_lock_file_for_update(&write_lock, merge_rr_path, 1);
 431         read_rr(&merge_rr);
 432
 433         if (argc < 2)
 434                 return do_plain_rerere(&merge_rr, fd);
 435         else if (!strcmp(argv[1], "clear")) {
 436                 for (i = 0; i < merge_rr.nr; i++) {
 437                         struct stat st;
 438                         const char *name = (const char *)merge_rr.items[i].util;
 439                         if (!stat(git_path("rr-cache/%s", name), &st) &&
 440                                         S_ISDIR(st.st_mode) &&
 441                                         stat(rr_path(name, "postimage"), &st))
 442                                 unlink_rr_item(name);
 443                 }
 444                 unlink(merge_rr_path);
 445         } else if (!strcmp(argv[1], "gc"))
 446                 garbage_collect(&merge_rr);
 447         else if (!strcmp(argv[1], "status"))
 448                 for (i = 0; i < merge_rr.nr; i++)
 449                         printf("%s\n", merge_rr.items[i].path);
 450         else if (!strcmp(argv[1], "diff"))
 451                 for (i = 0; i < merge_rr.nr; i++) {
 452                         const char *path = merge_rr.items[i].path;
 453                         const char *name = (const char *)merge_rr.items[i].util;
 454                         diff_two(rr_path(name, "preimage"), path, path, path);
 455                 }
 456         else
 457                 usage(git_rerere_usage);
 458
 459         path_list_clear(&merge_rr, 1);
 460         return 0;
 461 }