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_str_in_full(out_fd, "\t") != 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 struct rerere_io {
  87         int (*getline)(struct strbuf *, struct rerere_io *);
  88         FILE *output;
  89         int wrerror;
  90         /* some more stuff */
  91 };
  92
  93 static void rerere_io_putstr(const char *str, struct rerere_io *io)
  94 {
  95         if (io->output)
  96                 ferr_puts(str, io->output, &io->wrerror);
  97 }
  98
  99 static void rerere_io_putmem(const char *mem, size_t sz, struct rerere_io *io)
 100 {
 101         if (io->output)
 102                 ferr_write(mem, sz, io->output, &io->wrerror);
 103 }
 104
 105 struct rerere_io_file {
 106         struct rerere_io io;
 107         FILE *input;
 108 };
 109
 110 static int rerere_file_getline(struct strbuf *sb, struct rerere_io *io_)
 111 {
 112         struct rerere_io_file *io = (struct rerere_io_file *)io_;
 113         return strbuf_getwholeline(sb, io->input, '\n');
 114 }
 115
 116 static int handle_path(unsigned char *sha1, struct rerere_io *io)
 117 {
 118         git_SHA_CTX ctx;
 119         int hunk_no = 0;
 120         enum {
 121                 RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL,
 122         } hunk = RR_CONTEXT;
 123         struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
 124         struct strbuf buf = STRBUF_INIT;
 125
 126         if (sha1)
 127                 git_SHA1_Init(&ctx);
 128
 129         while (!io->getline(&buf, io)) {
 130                 if (!prefixcmp(buf.buf, "<<<<<<< ")) {
 131                         if (hunk != RR_CONTEXT)
 132                                 goto bad;
 133                         hunk = RR_SIDE_1;
 134                 } else if (!prefixcmp(buf.buf, "|||||||") && isspace(buf.buf[7])) {
 135                         if (hunk != RR_SIDE_1)
 136                                 goto bad;
 137                         hunk = RR_ORIGINAL;
 138                 } else if (!prefixcmp(buf.buf, "=======") && isspace(buf.buf[7])) {
 139                         if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
 140                                 goto bad;
 141                         hunk = RR_SIDE_2;
 142                 } else if (!prefixcmp(buf.buf, ">>>>>>> ")) {
 143                         if (hunk != RR_SIDE_2)
 144                                 goto bad;
 145                         if (strbuf_cmp(&one, &two) > 0)
 146                                 strbuf_swap(&one, &two);
 147                         hunk_no++;
 148                         hunk = RR_CONTEXT;
 149                         rerere_io_putstr("<<<<<<<\n", io);
 150                         rerere_io_putmem(one.buf, one.len, io);
 151                         rerere_io_putstr("=======\n", io);
 152                         rerere_io_putmem(two.buf, two.len, io);
 153                         rerere_io_putstr(">>>>>>>\n", io);
 154                         if (sha1) {
 155                                 git_SHA1_Update(&ctx, one.buf ? one.buf : "",
 156                                             one.len + 1);
 157                                 git_SHA1_Update(&ctx, two.buf ? two.buf : "",
 158                                             two.len + 1);
 159                         }
 160                         strbuf_reset(&one);
 161                         strbuf_reset(&two);
 162                 } else if (hunk == RR_SIDE_1)
 163                         strbuf_addstr(&one, buf.buf);
 164                 else if (hunk == RR_ORIGINAL)
 165                         ; /* discard */
 166                 else if (hunk == RR_SIDE_2)
 167                         strbuf_addstr(&two, buf.buf);
 168                 else
 169                         rerere_io_putstr(buf.buf, io);
 170                 continue;
 171         bad:
 172                 hunk = 99; /* force error exit */
 173                 break;
 174         }
 175         strbuf_release(&one);
 176         strbuf_release(&two);
 177         strbuf_release(&buf);
 178
 179         if (sha1)
 180                 git_SHA1_Final(sha1, &ctx);
 181         if (hunk != RR_CONTEXT)
 182                 return -1;
 183         return hunk_no;
 184 }
 185
 186 static int handle_file(const char *path, unsigned char *sha1, const char *output)
 187 {
 188         int hunk_no = 0;
 189         struct rerere_io_file io;
 190
 191         memset(&io, 0, sizeof(io));
 192         io.io.getline = rerere_file_getline;
 193         io.input = fopen(path, "r");
 194         io.io.wrerror = 0;
 195         if (!io.input)
 196                 return error("Could not open %s", path);
 197
 198         if (output) {
 199                 io.io.output = fopen(output, "w");
 200                 if (!io.io.output) {
 201                         fclose(io.input);
 202                         return error("Could not write %s", output);
 203                 }
 204         }
 205
 206         hunk_no = handle_path(sha1, (struct rerere_io *)&io);
 207
 208         fclose(io.input);
 209         if (io.io.wrerror)
 210                 error("There were errors while writing %s (%s)",
 211                       path, strerror(io.io.wrerror));
 212         if (io.io.output && fclose(io.io.output))
 213                 io.io.wrerror = error("Failed to flush %s: %s",
 214                                       path, strerror(errno));
 215
 216         if (hunk_no < 0) {
 217                 if (output)
 218                         unlink_or_warn(output);
 219                 return error("Could not parse conflict hunks in %s", path);
 220         }
 221         if (io.io.wrerror)
 222                 return -1;
 223         return hunk_no;
 224 }
 225
 226 static int find_conflict(struct string_list *conflict)
 227 {
 228         int i;
 229         if (read_cache() < 0)
 230                 return error("Could not read index");
 231         for (i = 0; i+1 < active_nr; i++) {
 232                 struct cache_entry *e2 = active_cache[i];
 233                 struct cache_entry *e3 = active_cache[i+1];
 234                 if (ce_stage(e2) == 2 &&
 235                     ce_stage(e3) == 3 &&
 236                     ce_same_name(e2, e3) &&
 237                     S_ISREG(e2->ce_mode) &&
 238                     S_ISREG(e3->ce_mode)) {
 239                         string_list_insert((const char *)e2->name, conflict);
 240                         i++; /* skip over both #2 and #3 */
 241                 }
 242         }
 243         return 0;
 244 }
 245
 246 static int merge(const char *name, const char *path)
 247 {
 248         int ret;
 249         mmfile_t cur, base, other;
 250         mmbuffer_t result = {NULL, 0};
 251         xpparam_t xpp = {XDF_NEED_MINIMAL};
 252
 253         if (handle_file(path, NULL, rerere_path(name, "thisimage")) < 0)
 254                 return 1;
 255
 256         if (read_mmfile(&cur, rerere_path(name, "thisimage")) ||
 257                         read_mmfile(&base, rerere_path(name, "preimage")) ||
 258                         read_mmfile(&other, rerere_path(name, "postimage")))
 259                 return 1;
 260         ret = xdl_merge(&base, &cur, "", &other, "",
 261                         &xpp, XDL_MERGE_ZEALOUS, &result);
 262         if (!ret) {
 263                 FILE *f = fopen(path, "w");
 264                 if (!f)
 265                         return error("Could not open %s: %s", path,
 266                                      strerror(errno));
 267                 if (fwrite(result.ptr, result.size, 1, f) != 1)
 268                         error("Could not write %s: %s", path, strerror(errno));
 269                 if (fclose(f))
 270                         return error("Writing %s failed: %s", path,
 271                                      strerror(errno));
 272         }
 273
 274         free(cur.ptr);
 275         free(base.ptr);
 276         free(other.ptr);
 277         free(result.ptr);
 278
 279         return ret;
 280 }
 281
 282 static struct lock_file index_lock;
 283
 284 static int update_paths(struct string_list *update)
 285 {
 286         int i;
 287         int fd = hold_locked_index(&index_lock, 0);
 288         int status = 0;
 289
 290         if (fd < 0)
 291                 return -1;
 292
 293         for (i = 0; i < update->nr; i++) {
 294                 struct string_list_item *item = &update->items[i];
 295                 if (add_file_to_cache(item->string, ADD_CACHE_IGNORE_ERRORS))
 296                         status = -1;
 297         }
 298
 299         if (!status && active_cache_changed) {
 300                 if (write_cache(fd, active_cache, active_nr) ||
 301                     commit_locked_index(&index_lock))
 302                         die("Unable to write new index file");
 303         } else if (fd >= 0)
 304                 rollback_lock_file(&index_lock);
 305         return status;
 306 }
 307
 308 static int do_plain_rerere(struct string_list *rr, int fd)
 309 {
 310         struct string_list conflict = { NULL, 0, 0, 1 };
 311         struct string_list update = { NULL, 0, 0, 1 };
 312         int i;
 313
 314         find_conflict(&conflict);
 315
 316         /*
 317          * MERGE_RR records paths with conflicts immediately after merge
 318          * failed.  Some of the conflicted paths might have been hand resolved
 319          * in the working tree since then, but the initial run would catch all
 320          * and register their preimages.
 321          */
 322
 323         for (i = 0; i < conflict.nr; i++) {
 324                 const char *path = conflict.items[i].string;
 325                 if (!string_list_has_string(rr, path)) {
 326                         unsigned char sha1[20];
 327                         char *hex;
 328                         int ret;
 329                         ret = handle_file(path, sha1, NULL);
 330                         if (ret < 1)
 331                                 continue;
 332                         hex = xstrdup(sha1_to_hex(sha1));
 333                         string_list_insert(path, rr)->util = hex;
 334                         if (mkdir(git_path("rr-cache/%s", hex), 0755))
 335                                 continue;
 336                         handle_file(path, NULL, rerere_path(hex, "preimage"));
 337                         fprintf(stderr, "Recorded preimage for '%s'\n", path);
 338                 }
 339         }
 340
 341         /*
 342          * Now some of the paths that had conflicts earlier might have been
 343          * hand resolved.  Others may be similar to a conflict already that
 344          * was resolved before.
 345          */
 346
 347         for (i = 0; i < rr->nr; i++) {
 348                 int ret;
 349                 const char *path = rr->items[i].string;
 350                 const char *name = (const char *)rr->items[i].util;
 351
 352                 if (has_rerere_resolution(name)) {
 353                         if (!merge(name, path)) {
 354                                 if (rerere_autoupdate)
 355                                         string_list_insert(path, &update);
 356                                 fprintf(stderr,
 357                                         "%s '%s' using previous resolution.\n",
 358                                         rerere_autoupdate
 359                                         ? "Staged" : "Resolved",
 360                                         path);
 361                                 goto mark_resolved;
 362                         }
 363                 }
 364
 365                 /* Let's see if we have resolved it. */
 366                 ret = handle_file(path, NULL, NULL);
 367                 if (ret)
 368                         continue;
 369
 370                 fprintf(stderr, "Recorded resolution for '%s'.\n", path);
 371                 copy_file(rerere_path(name, "postimage"), path, 0666);
 372         mark_resolved:
 373                 rr->items[i].util = NULL;
 374         }
 375
 376         if (update.nr)
 377                 update_paths(&update);
 378
 379         return write_rr(rr, fd);
 380 }
 381
 382 static int git_rerere_config(const char *var, const char *value, void *cb)
 383 {
 384         if (!strcmp(var, "rerere.enabled"))
 385                 rerere_enabled = git_config_bool(var, value);
 386         else if (!strcmp(var, "rerere.autoupdate"))
 387                 rerere_autoupdate = git_config_bool(var, value);
 388         else
 389                 return git_default_config(var, value, cb);
 390         return 0;
 391 }
 392
 393 static int is_rerere_enabled(void)
 394 {
 395         const char *rr_cache;
 396         int rr_cache_exists;
 397
 398         if (!rerere_enabled)
 399                 return 0;
 400
 401         rr_cache = git_path("rr-cache");
 402         rr_cache_exists = is_directory(rr_cache);
 403         if (rerere_enabled < 0)
 404                 return rr_cache_exists;
 405
 406         if (!rr_cache_exists &&
 407             (mkdir(rr_cache, 0777) || adjust_shared_perm(rr_cache)))
 408                 die("Could not create directory %s", rr_cache);
 409         return 1;
 410 }
 411
 412 int setup_rerere(struct string_list *merge_rr)
 413 {
 414         int fd;
 415
 416         git_config(git_rerere_config, NULL);
 417         if (!is_rerere_enabled())
 418                 return -1;
 419
 420         merge_rr_path = git_pathdup("MERGE_RR");
 421         fd = hold_lock_file_for_update(&write_lock, merge_rr_path,
 422                                        LOCK_DIE_ON_ERROR);
 423         read_rr(merge_rr);
 424         return fd;
 425 }
 426
 427 int rerere(void)
 428 {
 429         struct string_list merge_rr = { NULL, 0, 0, 1 };
 430         int fd;
 431
 432         fd = setup_rerere(&merge_rr);
 433         if (fd < 0)
 434                 return 0;
 435         return do_plain_rerere(&merge_rr, fd);
 436 }