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