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