rerere.c

   1 #include "cache.h"
   2 #include "string-list.h"
   3 #include "rerere.h"
   4 #include "xdiff/xdiff.h"
   5 #include "xdiff-interface.h"
   6
   7 /* if rerere_enabled == -1, fall back to detection of .git/rr-cache */
   8 static int rerere_enabled = -1;
   9
  10 /* automatically update cleanly resolved paths to the index */
  11 static int rerere_autoupdate;
  12
  13 static char *merge_rr_path;
  14
  15 const char *rerere_path(const char *hex, const char *file)
  16 {
  17         return git_path("rr-cache/%s/%s", hex, file);
  18 }
  19
  20 int has_rerere_resolution(const char *hex)
  21 {
  22         struct stat st;
  23         return !stat(rerere_path(hex, "postimage"), &st);
  24 }
  25
  26 static void read_rr(struct string_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                 string_list_insert(buf, rr)->util = name;
  47         }
  48         fclose(in);
  49 }
  50
  51 static struct lock_file write_lock;
  52
  53 static int write_rr(struct string_list *rr, int out_fd)
  54 {
  55         int i;
  56         for (i = 0; i < rr->nr; i++) {
  57                 const char *path;
  58                 int length;
  59                 if (!rr->items[i].util)
  60                         continue;
  61                 path = rr->items[i].string;
  62                 length = strlen(path) + 1;
  63                 if (write_in_full(out_fd, rr->items[i].util, 40) != 40 ||
  64                     write_in_full(out_fd, "\t", 1) != 1 ||
  65                     write_in_full(out_fd, path, length) != length)
  66                         die("unable to write rerere record");
  67         }
  68         if (commit_lock_file(&write_lock) != 0)
  69                 die("unable to write rerere record");
  70         return 0;
  71 }
  72
  73 static void ferr_write(const void *p, size_t count, FILE *fp, int *err)
  74 {
  75         if (!count || *err)
  76                 return;
  77         if (fwrite(p, count, 1, fp) != 1)
  78                 *err = errno;
  79 }
  80
  81 static inline void ferr_puts(const char *s, FILE *fp, int *err)
  82 {
  83         ferr_write(s, strlen(s), fp, err);
  84 }
  85
  86 static int handle_file(const char *path,
  87          unsigned char *sha1, const char *output)
  88 {
  89         git_SHA_CTX ctx;
  90         char buf[1024];
  91         int hunk_no = 0;
  92         enum {
  93                 RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL,
  94         } hunk = RR_CONTEXT;
  95         struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
  96         FILE *f = fopen(path, "r");
  97         FILE *out = NULL;
  98         int wrerror = 0;
  99
 100         if (!f)
 101                 return error("Could not open %s", path);
 102
 103         if (output) {
 104                 out = fopen(output, "w");
 105                 if (!out) {
 106                         fclose(f);
 107                         return error("Could not write %s", output);
 108                 }
 109         }
 110
 111         if (sha1)
 112                 git_SHA1_Init(&ctx);
 113
 114         while (fgets(buf, sizeof(buf), f)) {
 115                 if (!prefixcmp(buf, "<<<<<<< ")) {
 116                         if (hunk != RR_CONTEXT)
 117                                 goto bad;
 118                         hunk = RR_SIDE_1;
 119                 } else if (!prefixcmp(buf, "|||||||") && isspace(buf[7])) {
 120                         if (hunk != RR_SIDE_1)
 121                                 goto bad;
 122                         hunk = RR_ORIGINAL;
 123                 } else if (!prefixcmp(buf, "=======") && isspace(buf[7])) {
 124                         if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
 125                                 goto bad;
 126                         hunk = RR_SIDE_2;
 127                 } else if (!prefixcmp(buf, ">>>>>>> ")) {
 128                         if (hunk != RR_SIDE_2)
 129                                 goto bad;
 130                         if (strbuf_cmp(&one, &two) > 0)
 131                                 strbuf_swap(&one, &two);
 132                         hunk_no++;
 133                         hunk = RR_CONTEXT;
 134                         if (out) {
 135                                 ferr_puts("<<<<<<<\n", out, &wrerror);
 136                                 ferr_write(one.buf, one.len, out, &wrerror);
 137                                 ferr_puts("=======\n", out, &wrerror);
 138                                 ferr_write(two.buf, two.len, out, &wrerror);
 139                                 ferr_puts(">>>>>>>\n", out, &wrerror);
 140                         }
 141                         if (sha1) {
 142                                 git_SHA1_Update(&ctx, one.buf ? one.buf : "",
 143                                             one.len + 1);
 144                                 git_SHA1_Update(&ctx, two.buf ? two.buf : "",
 145                                             two.len + 1);
 146                         }
 147                         strbuf_reset(&one);
 148                         strbuf_reset(&two);
 149                 } else if (hunk == RR_SIDE_1)
 150                         strbuf_addstr(&one, buf);
 151                 else if (hunk == RR_ORIGINAL)
 152                         ; /* discard */
 153                 else if (hunk == RR_SIDE_2)
 154                         strbuf_addstr(&two, buf);
 155                 else if (out)
 156                         ferr_puts(buf, out, &wrerror);
 157                 continue;
 158         bad:
 159                 hunk = 99; /* force error exit */
 160                 break;
 161         }
 162         strbuf_release(&one);
 163         strbuf_release(&two);
 164
 165         fclose(f);
 166         if (wrerror)
 167                 error("There were errors while writing %s (%s)",
 168                       path, strerror(wrerror));
 169         if (out && fclose(out))
 170                 wrerror = error("Failed to flush %s: %s",
 171                                 path, strerror(errno));
 172         if (sha1)
 173                 git_SHA1_Final(sha1, &ctx);
 174         if (hunk != RR_CONTEXT) {
 175                 if (output)
 176                         unlink_or_warn(output);
 177                 return error("Could not parse conflict hunks in %s", path);
 178         }
 179         if (wrerror)
 180                 return -1;
 181         return hunk_no;
 182 }
 183
 184 static int find_conflict(struct string_list *conflict)
 185 {
 186         int i;
 187         if (read_cache() < 0)
 188                 return error("Could not read index");
 189         for (i = 0; i+1 < active_nr; i++) {
 190                 struct cache_entry *e2 = active_cache[i];
 191                 struct cache_entry *e3 = active_cache[i+1];
 192                 if (ce_stage(e2) == 2 &&
 193                     ce_stage(e3) == 3 &&
 194                     ce_same_name(e2, e3) &&
 195                     S_ISREG(e2->ce_mode) &&
 196                     S_ISREG(e3->ce_mode)) {
 197                         string_list_insert((const char *)e2->name, conflict);
 198                         i++; /* skip over both #2 and #3 */
 199                 }
 200         }
 201         return 0;
 202 }
 203
 204 static int merge(const char *name, const char *path)
 205 {
 206         int ret;
 207         mmfile_t cur, base, other;
 208         mmbuffer_t result = {NULL, 0};
 209         xpparam_t xpp = {XDF_NEED_MINIMAL};
 210
 211         if (handle_file(path, NULL, rerere_path(name, "thisimage")) < 0)
 212                 return 1;
 213
 214         if (read_mmfile(&cur, rerere_path(name, "thisimage")) ||
 215                         read_mmfile(&base, rerere_path(name, "preimage")) ||
 216                         read_mmfile(&other, rerere_path(name, "postimage")))
 217                 return 1;
 218         ret = xdl_merge(&base, &cur, "", &other, "",
 219                         &xpp, XDL_MERGE_ZEALOUS, &result);
 220         if (!ret) {
 221                 FILE *f = fopen(path, "w");
 222                 if (!f)
 223                         return error("Could not open %s: %s", path,
 224                                      strerror(errno));
 225                 if (fwrite(result.ptr, result.size, 1, f) != 1)
 226                         error("Could not write %s: %s", path, strerror(errno));
 227                 if (fclose(f))
 228                         return error("Writing %s failed: %s", path,
 229                                      strerror(errno));
 230         }
 231
 232         free(cur.ptr);
 233         free(base.ptr);
 234         free(other.ptr);
 235         free(result.ptr);
 236
 237         return ret;
 238 }
 239
 240 static struct lock_file index_lock;
 241
 242 static int update_paths(struct string_list *update)
 243 {
 244         int i;
 245         int fd = hold_locked_index(&index_lock, 0);
 246         int status = 0;
 247
 248         if (fd < 0)
 249                 return -1;
 250
 251         for (i = 0; i < update->nr; i++) {
 252                 struct string_list_item *item = &update->items[i];
 253                 if (add_file_to_cache(item->string, ADD_CACHE_IGNORE_ERRORS))
 254                         status = -1;
 255         }
 256
 257         if (!status && active_cache_changed) {
 258                 if (write_cache(fd, active_cache, active_nr) ||
 259                     commit_locked_index(&index_lock))
 260                         die("Unable to write new index file");
 261         } else if (fd >= 0)
 262                 rollback_lock_file(&index_lock);
 263         return status;
 264 }
 265
 266 static int do_plain_rerere(struct string_list *rr, int fd)
 267 {
 268         struct string_list conflict = { NULL, 0, 0, 1 };
 269         struct string_list update = { NULL, 0, 0, 1 };
 270         int i;
 271
 272         find_conflict(&conflict);
 273
 274         /*
 275          * MERGE_RR records paths with conflicts immediately after merge
 276          * failed.  Some of the conflicted paths might have been hand resolved
 277          * in the working tree since then, but the initial run would catch all
 278          * and register their preimages.
 279          */
 280
 281         for (i = 0; i < conflict.nr; i++) {
 282                 const char *path = conflict.items[i].string;
 283                 if (!string_list_has_string(rr, path)) {
 284                         unsigned char sha1[20];
 285                         char *hex;
 286                         int ret;
 287                         ret = handle_file(path, sha1, NULL);
 288                         if (ret < 1)
 289                                 continue;
 290                         hex = xstrdup(sha1_to_hex(sha1));
 291                         string_list_insert(path, rr)->util = hex;
 292                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 293                                 continue;
 294                         handle_file(path, NULL, rerere_path(hex, "preimage"));
 295                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 296                 }
 297         }
 298
 299         /*
 300          * Now some of the paths that had conflicts earlier might have been
 301          * hand resolved.  Others may be similar to a conflict already that
 302          * was resolved before.
 303          */
 304
 305         for (i = 0; i < rr->nr; i++) {
 306                 int ret;
 307                 const char *path = rr->items[i].string;
 308                 const char *name = (const char *)rr->items[i].util;
 309
 310                 if (has_rerere_resolution(name)) {
 311                         if (!merge(name, path)) {
 312                                 if (rerere_autoupdate)
 313                                         string_list_insert(path, &update);
 314                                 fprintf(stderr,
 315                                         "%s '%s' using previous resolution.\n",
 316                                         rerere_autoupdate
 317                                         ? "Staged" : "Resolved",
 318                                         path);
 319                                 goto mark_resolved;
 320                         }
 321                 }
 322
 323                 /* Let's see if we have resolved it. */
 324                 ret = handle_file(path, NULL, NULL);
 325                 if (ret)
 326                         continue;
 327
 328                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 329                 copy_file(rerere_path(name, "postimage"), path, 0666);
 330         mark_resolved:
 331                 rr->items[i].util = NULL;
 332         }
 333
 334         if (update.nr)
 335                 update_paths(&update);
 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, "rerere.enabled"))
 343                 rerere_enabled = git_config_bool(var, value);
 344         else if (!strcmp(var, "rerere.autoupdate"))
 345                 rerere_autoupdate = git_config_bool(var, value);
 346         else
 347                 return git_default_config(var, value, cb);
 348         return 0;
 349 }
 350
 351 static int is_rerere_enabled(void)
 352 {
 353         const char *rr_cache;
 354         int rr_cache_exists;
 355
 356         if (!rerere_enabled)
 357                 return 0;
 358
 359         rr_cache = git_path("rr-cache");
 360         rr_cache_exists = is_directory(rr_cache);
 361         if (rerere_enabled < 0)
 362                 return rr_cache_exists;
 363
 364         if (!rr_cache_exists &&
 365             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 366                 die("Could not create directory %s", rr_cache);
 367         return 1;
 368 }
 369
 370 int setup_rerere(struct string_list *merge_rr)
 371 {
 372         int fd;
 373
 374         git_config(git_rerere_config, NULL);
 375         if (!is_rerere_enabled())
 376                 return -1;
 377
 378         merge_rr_path = git_pathdup("MERGE_RR");
 379         fd = hold_lock_file_for_update(&write_lock, merge_rr_path,
 380                                        LOCK_DIE_ON_ERROR);
 381         read_rr(merge_rr);
 382         return fd;
 383 }
 384
 385 int rerere(void)
 386 {
 387         struct string_list merge_rr = { NULL, 0, 0, 1 };
 388         int fd;
 389
 390         fd = setup_rerere(&merge_rr);
 391         if (fd < 0)
 392                 return 0;
 393         return do_plain_rerere(&merge_rr, fd);
 394 }