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         return hunk_no;
 148 }
 149
 150 static int find_conflict(struct path_list *conflict)
 151 {
 152         int i;
 153         if (read_cache() < 0)
 154                 return error("Could not read index");
 155         for (i = 0; i+1 < active_nr; i++) {
 156                 struct cache_entry *e2 = active_cache[i];
 157                 struct cache_entry *e3 = active_cache[i+1];
 158                 if (ce_stage(e2) == 2 &&
 159                     ce_stage(e3) == 3 &&
 160                     ce_same_name(e2, e3) &&
 161                     S_ISREG(e2->ce_mode) &&
 162                     S_ISREG(e3->ce_mode)) {
 163                         path_list_insert((const char *)e2->name, conflict);
 164                         i++; /* skip over both #2 and #3 */
 165                 }
 166         }
 167         return 0;
 168 }
 169
 170 static int merge(const char *name, const char *path)
 171 {
 172         int ret;
 173         mmfile_t cur, base, other;
 174         mmbuffer_t result = {NULL, 0};
 175         xpparam_t xpp = {XDF_NEED_MINIMAL};
 176
 177         if (handle_file(path, NULL, rr_path(name, "thisimage")) < 0)
 178                 return 1;
 179
 180         if (read_mmfile(&cur, rr_path(name, "thisimage")) ||
 181                         read_mmfile(&base, rr_path(name, "preimage")) ||
 182                         read_mmfile(&other, rr_path(name, "postimage")))
 183                 return 1;
 184         ret = xdl_merge(&base, &cur, "", &other, "",
 185                         &xpp, XDL_MERGE_ZEALOUS, &result);
 186         if (!ret) {
 187                 FILE *f = fopen(path, "w");
 188                 if (!f)
 189                         return error("Could not write to %s", path);
 190                 fwrite(result.ptr, result.size, 1, f);
 191                 fclose(f);
 192         }
 193
 194         free(cur.ptr);
 195         free(base.ptr);
 196         free(other.ptr);
 197         free(result.ptr);
 198
 199         return ret;
 200 }
 201
 202 static void unlink_rr_item(const char *name)
 203 {
 204         unlink(rr_path(name, "thisimage"));
 205         unlink(rr_path(name, "preimage"));
 206         unlink(rr_path(name, "postimage"));
 207         rmdir(git_path("rr-cache/%s", name));
 208 }
 209
 210 static void garbage_collect(struct path_list *rr)
 211 {
 212         struct path_list to_remove = { NULL, 0, 0, 1 };
 213         DIR *dir;
 214         struct dirent *e;
 215         int i, cutoff;
 216         time_t now = time(NULL), then;
 217
 218         dir = opendir(git_path("rr-cache"));
 219         while ((e = readdir(dir))) {
 220                 const char *name = e->d_name;
 221                 if (name[0] == '.' &&
 222                     (name[1] == '\0' || (name[1] == '.' && name[2] == '\0')))
 223                         continue;
 224                 then = rerere_created_at(name);
 225                 if (!then)
 226                         continue;
 227                 cutoff = (has_resolution(name)
 228                           ? cutoff_resolve : cutoff_noresolve);
 229                 if (then < now - cutoff * 86400)
 230                         path_list_append(name, &to_remove);
 231         }
 232         for (i = 0; i < to_remove.nr; i++)
 233                 unlink_rr_item(to_remove.items[i].path);
 234         path_list_clear(&to_remove, 0);
 235 }
 236
 237 static int outf(void *dummy, mmbuffer_t *ptr, int nbuf)
 238 {
 239         int i;
 240         for (i = 0; i < nbuf; i++)
 241                 if (write_in_full(1, ptr[i].ptr, ptr[i].size) != ptr[i].size)
 242                         return -1;
 243         return 0;
 244 }
 245
 246 static int diff_two(const char *file1, const char *label1,
 247                 const char *file2, const char *label2)
 248 {
 249         xpparam_t xpp;
 250         xdemitconf_t xecfg;
 251         xdemitcb_t ecb;
 252         mmfile_t minus, plus;
 253
 254         if (read_mmfile(&minus, file1) || read_mmfile(&plus, file2))
 255                 return 1;
 256
 257         printf("--- a/%s\n+++ b/%s\n", label1, label2);
 258         fflush(stdout);
 259         xpp.flags = XDF_NEED_MINIMAL;
 260         memset(&xecfg, 0, sizeof(xecfg));
 261         xecfg.ctxlen = 3;
 262         ecb.outf = outf;
 263         xdi_diff(&minus, &plus, &xpp, &xecfg, &ecb);
 264
 265         free(minus.ptr);
 266         free(plus.ptr);
 267         return 0;
 268 }
 269
 270 static int do_plain_rerere(struct path_list *rr, int fd)
 271 {
 272         struct path_list conflict = { NULL, 0, 0, 1 };
 273         int i;
 274
 275         find_conflict(&conflict);
 276
 277         /*
 278          * MERGE_RR records paths with conflicts immediately after merge
 279          * failed.  Some of the conflicted paths might have been hand resolved
 280          * in the working tree since then, but the initial run would catch all
 281          * and register their preimages.
 282          */
 283
 284         for (i = 0; i < conflict.nr; i++) {
 285                 const char *path = conflict.items[i].path;
 286                 if (!path_list_has_path(rr, path)) {
 287                         unsigned char sha1[20];
 288                         char *hex;
 289                         int ret;
 290                         ret = handle_file(path, sha1, NULL);
 291                         if (ret < 1)
 292                                 continue;
 293                         hex = xstrdup(sha1_to_hex(sha1));
 294                         path_list_insert(path, rr)->util = hex;
 295                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 296                                 continue;;
 297                         handle_file(path, NULL, rr_path(hex, "preimage"));
 298                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 299                 }
 300         }
 301
 302         /*
 303          * Now some of the paths that had conflicts earlier might have been
 304          * hand resolved.  Others may be similar to a conflict already that
 305          * was resolved before.
 306          */
 307
 308         for (i = 0; i < rr->nr; i++) {
 309                 int ret;
 310                 const char *path = rr->items[i].path;
 311                 const char *name = (const char *)rr->items[i].util;
 312
 313                 if (has_resolution(name)) {
 314                         if (!merge(name, path)) {
 315                                 fprintf(stderr, "Resolved '%s' using "
 316                                                 "previous resolution.\n", path);
 317                                 goto tail_optimization;
 318                         }
 319                 }
 320
 321                 /* Let's see if we have resolved it. */
 322                 ret = handle_file(path, NULL, NULL);
 323                 if (ret)
 324                         continue;
 325
 326                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 327                 copy_file(rr_path(name, "postimage"), path, 0666);
 328 tail_optimization:
 329                 if (i < rr->nr - 1)
 330                         memmove(rr->items + i,
 331                                 rr->items + i + 1,
 332                                 sizeof(rr->items[0]) * (rr->nr - i - 1));
 333                 rr->nr--;
 334                 i--;
 335         }
 336
 337         return write_rr(rr, fd);
 338 }
 339
 340 static int git_rerere_config(const char *var, const char *value, void *cb)
 341 {
 342         if (!strcmp(var, "gc.rerereresolved"))
 343                 cutoff_resolve = git_config_int(var, value);
 344         else if (!strcmp(var, "gc.rerereunresolved"))
 345                 cutoff_noresolve = git_config_int(var, value);
 346         else if (!strcmp(var, "rerere.enabled"))
 347                 rerere_enabled = git_config_bool(var, value);
 348         else
 349                 return git_default_config(var, value, cb);
 350         return 0;
 351 }
 352
 353 static int is_rerere_enabled(void)
 354 {
 355         struct stat st;
 356         const char *rr_cache;
 357         int rr_cache_exists;
 358
 359         if (!rerere_enabled)
 360                 return 0;
 361
 362         rr_cache = git_path("rr-cache");
 363         rr_cache_exists = !stat(rr_cache, &st) && S_ISDIR(st.st_mode);
 364         if (rerere_enabled < 0)
 365                 return rr_cache_exists;
 366
 367         if (!rr_cache_exists &&
 368             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 369                 die("Could not create directory %s", rr_cache);
 370         return 1;
 371 }
 372
 373 static int setup_rerere(struct path_list *merge_rr)
 374 {
 375         int fd;
 376
 377         git_config(git_rerere_config, NULL);
 378         if (!is_rerere_enabled())
 379                 return -1;
 380
 381         merge_rr_path = xstrdup(git_path("rr-cache/MERGE_RR"));
 382         fd = hold_lock_file_for_update(&write_lock, merge_rr_path, 1);
 383         read_rr(merge_rr);
 384         return fd;
 385 }
 386
 387 int rerere(void)
 388 {
 389         struct path_list merge_rr = { NULL, 0, 0, 1 };
 390         int fd;
 391
 392         fd = setup_rerere(&merge_rr);
 393         if (fd < 0)
 394                 return 0;
 395         return do_plain_rerere(&merge_rr, fd);
 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;
 402
 403         fd = setup_rerere(&merge_rr);
 404         if (fd < 0)
 405                 return 0;
 406
 407         if (argc < 2)
 408                 return do_plain_rerere(&merge_rr, fd);
 409         else if (!strcmp(argv[1], "clear")) {
 410                 for (i = 0; i < merge_rr.nr; i++) {
 411                         const char *name = (const char *)merge_rr.items[i].util;
 412                         if (!has_resolution(name))
 413                                 unlink_rr_item(name);
 414                 }
 415                 unlink(merge_rr_path);
 416         } else if (!strcmp(argv[1], "gc"))
 417                 garbage_collect(&merge_rr);
 418         else if (!strcmp(argv[1], "status"))
 419                 for (i = 0; i < merge_rr.nr; i++)
 420                         printf("%s\n", merge_rr.items[i].path);
 421         else if (!strcmp(argv[1], "diff"))
 422                 for (i = 0; i < merge_rr.nr; i++) {
 423                         const char *path = merge_rr.items[i].path;
 424                         const char *name = (const char *)merge_rr.items[i].util;
 425                         diff_two(rr_path(name, "preimage"), path, path, path);
 426                 }
 427         else
 428                 usage(git_rerere_usage);
 429
 430         path_list_clear(&merge_rr, 1);
 431         return 0;
 432 }