builtin-rerere.c

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