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