src/basic/fileio.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <ctype.h>
   4 #include <errno.h>
   5 #include <fcntl.h>
   6 #include <limits.h>
   7 #include <stdarg.h>
   8 #include <stdint.h>
   9 #include <stdio_ext.h>
  10 #include <stdlib.h>
  11 #include <string.h>
  12 #include <sys/stat.h>
  13 #include <sys/types.h>
  14 #include <unistd.h>
  15
  16 #include "alloc-util.h"
  17 #include "fd-util.h"
  18 #include "fileio.h"
  19 #include "fs-util.h"
  20 #include "log.h"
  21 #include "macro.h"
  22 #include "missing.h"
  23 #include "parse-util.h"
  24 #include "path-util.h"
  25 #include "stdio-util.h"
  26 #include "string-util.h"
  27 #include "tmpfile-util.h"
  28
  29 #define READ_FULL_BYTES_MAX (4U*1024U*1024U)
  30
  31 int write_string_stream_ts(
  32                 FILE *f,
  33                 const char *line,
  34                 WriteStringFileFlags flags,
  35                 struct timespec *ts) {
  36
  37         bool needs_nl;
  38         int r;
  39
  40         assert(f);
  41         assert(line);
  42
  43         if (ferror(f))
  44                 return -EIO;
  45
  46         needs_nl = !(flags & WRITE_STRING_FILE_AVOID_NEWLINE) && !endswith(line, "\n");
  47
  48         if (needs_nl && (flags & WRITE_STRING_FILE_DISABLE_BUFFER)) {
  49                 /* If STDIO buffering was disabled, then let's append the newline character to the string itself, so
  50                  * that the write goes out in one go, instead of two */
  51
  52                 line = strjoina(line, "\n");
  53                 needs_nl = false;
  54         }
  55
  56         if (fputs(line, f) == EOF)
  57                 return -errno;
  58
  59         if (needs_nl)
  60                 if (fputc('\n', f) == EOF)
  61                         return -errno;
  62
  63         if (flags & WRITE_STRING_FILE_SYNC)
  64                 r = fflush_sync_and_check(f);
  65         else
  66                 r = fflush_and_check(f);
  67         if (r < 0)
  68                 return r;
  69
  70         if (ts) {
  71                 struct timespec twice[2] = {*ts, *ts};
  72
  73                 if (futimens(fileno(f), twice) < 0)
  74                         return -errno;
  75         }
  76
  77         return 0;
  78 }
  79
  80 static int write_string_file_atomic(
  81                 const char *fn,
  82                 const char *line,
  83                 WriteStringFileFlags flags,
  84                 struct timespec *ts) {
  85
  86         _cleanup_fclose_ FILE *f = NULL;
  87         _cleanup_free_ char *p = NULL;
  88         int r;
  89
  90         assert(fn);
  91         assert(line);
  92
  93         r = fopen_temporary(fn, &f, &p);
  94         if (r < 0)
  95                 return r;
  96
  97         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
  98         (void) fchmod_umask(fileno(f), 0644);
  99
 100         r = write_string_stream_ts(f, line, flags, ts);
 101         if (r < 0)
 102                 goto fail;
 103
 104         if (rename(p, fn) < 0) {
 105                 r = -errno;
 106                 goto fail;
 107         }
 108
 109         return 0;
 110
 111 fail:
 112         (void) unlink(p);
 113         return r;
 114 }
 115
 116 int write_string_file_ts(
 117                 const char *fn,
 118                 const char *line,
 119                 WriteStringFileFlags flags,
 120                 struct timespec *ts) {
 121
 122         _cleanup_fclose_ FILE *f = NULL;
 123         int q, r;
 124
 125         assert(fn);
 126         assert(line);
 127
 128         /* We don't know how to verify whether the file contents was already on-disk. */
 129         assert(!((flags & WRITE_STRING_FILE_VERIFY_ON_FAILURE) && (flags & WRITE_STRING_FILE_SYNC)));
 130
 131         if (flags & WRITE_STRING_FILE_ATOMIC) {
 132                 assert(flags & WRITE_STRING_FILE_CREATE);
 133
 134                 r = write_string_file_atomic(fn, line, flags, ts);
 135                 if (r < 0)
 136                         goto fail;
 137
 138                 return r;
 139         } else
 140                 assert(!ts);
 141
 142         if (flags & WRITE_STRING_FILE_CREATE) {
 143                 f = fopen(fn, "we");
 144                 if (!f) {
 145                         r = -errno;
 146                         goto fail;
 147                 }
 148         } else {
 149                 int fd;
 150
 151                 /* We manually build our own version of fopen(..., "we") that
 152                  * works without O_CREAT */
 153                 fd = open(fn, O_WRONLY|O_CLOEXEC|O_NOCTTY | ((flags & WRITE_STRING_FILE_NOFOLLOW) ? O_NOFOLLOW : 0));
 154                 if (fd < 0) {
 155                         r = -errno;
 156                         goto fail;
 157                 }
 158
 159                 f = fdopen(fd, "w");
 160                 if (!f) {
 161                         r = -errno;
 162                         safe_close(fd);
 163                         goto fail;
 164                 }
 165         }
 166
 167         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
 168
 169         if (flags & WRITE_STRING_FILE_DISABLE_BUFFER)
 170                 setvbuf(f, NULL, _IONBF, 0);
 171
 172         r = write_string_stream_ts(f, line, flags, ts);
 173         if (r < 0)
 174                 goto fail;
 175
 176         return 0;
 177
 178 fail:
 179         if (!(flags & WRITE_STRING_FILE_VERIFY_ON_FAILURE))
 180                 return r;
 181
 182         f = safe_fclose(f);
 183
 184         /* OK, the operation failed, but let's see if the right
 185          * contents in place already. If so, eat up the error. */
 186
 187         q = verify_file(fn, line, !(flags & WRITE_STRING_FILE_AVOID_NEWLINE));
 188         if (q <= 0)
 189                 return r;
 190
 191         return 0;
 192 }
 193
 194 int write_string_filef(
 195                 const char *fn,
 196                 WriteStringFileFlags flags,
 197                 const char *format, ...) {
 198
 199         _cleanup_free_ char *p = NULL;
 200         va_list ap;
 201         int r;
 202
 203         va_start(ap, format);
 204         r = vasprintf(&p, format, ap);
 205         va_end(ap);
 206
 207         if (r < 0)
 208                 return -ENOMEM;
 209
 210         return write_string_file(fn, p, flags);
 211 }
 212
 213 int read_one_line_file(const char *fn, char **line) {
 214         _cleanup_fclose_ FILE *f = NULL;
 215         int r;
 216
 217         assert(fn);
 218         assert(line);
 219
 220         f = fopen(fn, "re");
 221         if (!f)
 222                 return -errno;
 223
 224         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
 225
 226         r = read_line(f, LONG_LINE_MAX, line);
 227         return r < 0 ? r : 0;
 228 }
 229
 230 int verify_file(const char *fn, const char *blob, bool accept_extra_nl) {
 231         _cleanup_fclose_ FILE *f = NULL;
 232         _cleanup_free_ char *buf = NULL;
 233         size_t l, k;
 234
 235         assert(fn);
 236         assert(blob);
 237
 238         l = strlen(blob);
 239
 240         if (accept_extra_nl && endswith(blob, "\n"))
 241                 accept_extra_nl = false;
 242
 243         buf = malloc(l + accept_extra_nl + 1);
 244         if (!buf)
 245                 return -ENOMEM;
 246
 247         f = fopen(fn, "re");
 248         if (!f)
 249                 return -errno;
 250
 251         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
 252
 253         /* We try to read one byte more than we need, so that we know whether we hit eof */
 254         errno = 0;
 255         k = fread(buf, 1, l + accept_extra_nl + 1, f);
 256         if (ferror(f))
 257                 return errno > 0 ? -errno : -EIO;
 258
 259         if (k != l && k != l + accept_extra_nl)
 260                 return 0;
 261         if (memcmp(buf, blob, l) != 0)
 262                 return 0;
 263         if (k > l && buf[l] != '\n')
 264                 return 0;
 265
 266         return 1;
 267 }
 268
 269 int read_full_stream(
 270                 FILE *f,
 271                 char **ret_contents,
 272                 size_t *ret_size) {
 273
 274         _cleanup_free_ char *buf = NULL;
 275         struct stat st;
 276         size_t n, l;
 277         int fd;
 278
 279         assert(f);
 280         assert(ret_contents);
 281
 282         n = LINE_MAX; /* Start size */
 283
 284         fd = fileno(f);
 285         if (fd >= 0) { /* If the FILE* object is backed by an fd (as opposed to memory or such, see fmemopen(), let's
 286                         * optimize our buffering) */
 287
 288                 if (fstat(fileno(f), &st) < 0)
 289                         return -errno;
 290
 291                 if (S_ISREG(st.st_mode)) {
 292
 293                         /* Safety check */
 294                         if (st.st_size > READ_FULL_BYTES_MAX)
 295                                 return -E2BIG;
 296
 297                         /* Start with the right file size, but be prepared for files from /proc which generally report a file
 298                          * size of 0. Note that we increase the size to read here by one, so that the first read attempt
 299                          * already makes us notice the EOF. */
 300                         if (st.st_size > 0)
 301                                 n = st.st_size + 1;
 302                 }
 303         }
 304
 305         l = 0;
 306         for (;;) {
 307                 char *t;
 308                 size_t k;
 309
 310                 t = realloc(buf, n + 1);
 311                 if (!t)
 312                         return -ENOMEM;
 313
 314                 buf = t;
 315                 errno = 0;
 316                 k = fread(buf + l, 1, n - l, f);
 317                 if (k > 0)
 318                         l += k;
 319
 320                 if (ferror(f))
 321                         return errno > 0 ? -errno : -EIO;
 322
 323                 if (feof(f))
 324                         break;
 325
 326                 /* We aren't expecting fread() to return a short read outside
 327                  * of (error && eof), assert buffer is full and enlarge buffer.
 328                  */
 329                 assert(l == n);
 330
 331                 /* Safety check */
 332                 if (n >= READ_FULL_BYTES_MAX)
 333                         return -E2BIG;
 334
 335                 n = MIN(n * 2, READ_FULL_BYTES_MAX);
 336         }
 337
 338         if (!ret_size) {
 339                 /* Safety check: if the caller doesn't want to know the size of what we just read it will rely on the
 340                  * trailing NUL byte. But if there's an embedded NUL byte, then we should refuse operation as otherwise
 341                  * there'd be ambiguity about what we just read. */
 342
 343                 if (memchr(buf, 0, l))
 344                         return -EBADMSG;
 345         }
 346
 347         buf[l] = 0;
 348         *ret_contents = TAKE_PTR(buf);
 349
 350         if (ret_size)
 351                 *ret_size = l;
 352
 353         return 0;
 354 }
 355
 356 int read_full_file(const char *fn, char **contents, size_t *size) {
 357         _cleanup_fclose_ FILE *f = NULL;
 358
 359         assert(fn);
 360         assert(contents);
 361
 362         f = fopen(fn, "re");
 363         if (!f)
 364                 return -errno;
 365
 366         (void) __fsetlocking(f, FSETLOCKING_BYCALLER);
 367
 368         return read_full_stream(f, contents, size);
 369 }
 370
 371 int executable_is_script(const char *path, char **interpreter) {
 372         _cleanup_free_ char *line = NULL;
 373         size_t len;
 374         char *ans;
 375         int r;
 376
 377         assert(path);
 378
 379         r = read_one_line_file(path, &line);
 380         if (r == -ENOBUFS) /* First line overly long? if so, then it's not a script */
 381                 return 0;
 382         if (r < 0)
 383                 return r;
 384
 385         if (!startswith(line, "#!"))
 386                 return 0;
 387
 388         ans = strstrip(line + 2);
 389         len = strcspn(ans, " \t");
 390
 391         if (len == 0)
 392                 return 0;
 393
 394         ans = strndup(ans, len);
 395         if (!ans)
 396                 return -ENOMEM;
 397
 398         *interpreter = ans;
 399         return 1;
 400 }
 401
 402 /**
 403  * Retrieve one field from a file like /proc/self/status.  pattern
 404  * should not include whitespace or the delimiter (':'). pattern matches only
 405  * the beginning of a line. Whitespace before ':' is skipped. Whitespace and
 406  * zeros after the ':' will be skipped. field must be freed afterwards.
 407  * terminator specifies the terminating characters of the field value (not
 408  * included in the value).
 409  */
 410 int get_proc_field(const char *filename, const char *pattern, const char *terminator, char **field) {
 411         _cleanup_free_ char *status = NULL;
 412         char *t, *f;
 413         size_t len;
 414         int r;
 415
 416         assert(terminator);
 417         assert(filename);
 418         assert(pattern);
 419         assert(field);
 420
 421         r = read_full_file(filename, &status, NULL);
 422         if (r < 0)
 423                 return r;
 424
 425         t = status;
 426
 427         do {
 428                 bool pattern_ok;
 429
 430                 do {
 431                         t = strstr(t, pattern);
 432                         if (!t)
 433                                 return -ENOENT;
 434
 435                         /* Check that pattern occurs in beginning of line. */
 436                         pattern_ok = (t == status || t[-1] == '\n');
 437
 438                         t += strlen(pattern);
 439
 440                 } while (!pattern_ok);
 441
 442                 t += strspn(t, " \t");
 443                 if (!*t)
 444                         return -ENOENT;
 445
 446         } while (*t != ':');
 447
 448         t++;
 449
 450         if (*t) {
 451                 t += strspn(t, " \t");
 452
 453                 /* Also skip zeros, because when this is used for
 454                  * capabilities, we don't want the zeros. This way the
 455                  * same capability set always maps to the same string,
 456                  * irrespective of the total capability set size. For
 457                  * other numbers it shouldn't matter. */
 458                 t += strspn(t, "0");
 459                 /* Back off one char if there's nothing but whitespace
 460                    and zeros */
 461                 if (!*t || isspace(*t))
 462                         t--;
 463         }
 464
 465         len = strcspn(t, terminator);
 466
 467         f = strndup(t, len);
 468         if (!f)
 469                 return -ENOMEM;
 470
 471         *field = f;
 472         return 0;
 473 }
 474
 475 DIR *xopendirat(int fd, const char *name, int flags) {
 476         int nfd;
 477         DIR *d;
 478
 479         assert(!(flags & O_CREAT));
 480
 481         nfd = openat(fd, name, O_RDONLY|O_NONBLOCK|O_DIRECTORY|O_CLOEXEC|flags, 0);
 482         if (nfd < 0)
 483                 return NULL;
 484
 485         d = fdopendir(nfd);
 486         if (!d) {
 487                 safe_close(nfd);
 488                 return NULL;
 489         }
 490
 491         return d;
 492 }
 493
 494 static int search_and_fopen_internal(const char *path, const char *mode, const char *root, char **search, FILE **_f) {
 495         char **i;
 496
 497         assert(path);
 498         assert(mode);
 499         assert(_f);
 500
 501         if (!path_strv_resolve_uniq(search, root))
 502                 return -ENOMEM;
 503
 504         STRV_FOREACH(i, search) {
 505                 _cleanup_free_ char *p = NULL;
 506                 FILE *f;
 507
 508                 if (root)
 509                         p = strjoin(root, *i, "/", path);
 510                 else
 511                         p = strjoin(*i, "/", path);
 512                 if (!p)
 513                         return -ENOMEM;
 514
 515                 f = fopen(p, mode);
 516                 if (f) {
 517                         *_f = f;
 518                         return 0;
 519                 }
 520
 521                 if (errno != ENOENT)
 522                         return -errno;
 523         }
 524
 525         return -ENOENT;
 526 }
 527
 528 int search_and_fopen(const char *path, const char *mode, const char *root, const char **search, FILE **_f) {
 529         _cleanup_strv_free_ char **copy = NULL;
 530
 531         assert(path);
 532         assert(mode);
 533         assert(_f);
 534
 535         if (path_is_absolute(path)) {
 536                 FILE *f;
 537
 538                 f = fopen(path, mode);
 539                 if (f) {
 540                         *_f = f;
 541                         return 0;
 542                 }
 543
 544                 return -errno;
 545         }
 546
 547         copy = strv_copy((char**) search);
 548         if (!copy)
 549                 return -ENOMEM;
 550
 551         return search_and_fopen_internal(path, mode, root, copy, _f);
 552 }
 553
 554 int search_and_fopen_nulstr(const char *path, const char *mode, const char *root, const char *search, FILE **_f) {
 555         _cleanup_strv_free_ char **s = NULL;
 556
 557         if (path_is_absolute(path)) {
 558                 FILE *f;
 559
 560                 f = fopen(path, mode);
 561                 if (f) {
 562                         *_f = f;
 563                         return 0;
 564                 }
 565
 566                 return -errno;
 567         }
 568
 569         s = strv_split_nulstr(search);
 570         if (!s)
 571                 return -ENOMEM;
 572
 573         return search_and_fopen_internal(path, mode, root, s, _f);
 574 }
 575
 576 int fflush_and_check(FILE *f) {
 577         assert(f);
 578
 579         errno = 0;
 580         fflush(f);
 581
 582         if (ferror(f))
 583                 return errno > 0 ? -errno : -EIO;
 584
 585         return 0;
 586 }
 587
 588 int fflush_sync_and_check(FILE *f) {
 589         int r;
 590
 591         assert(f);
 592
 593         r = fflush_and_check(f);
 594         if (r < 0)
 595                 return r;
 596
 597         if (fsync(fileno(f)) < 0)
 598                 return -errno;
 599
 600         r = fsync_directory_of_file(fileno(f));
 601         if (r < 0)
 602                 return r;
 603
 604         return 0;
 605 }
 606
 607 int write_timestamp_file_atomic(const char *fn, usec_t n) {
 608         char ln[DECIMAL_STR_MAX(n)+2];
 609
 610         /* Creates a "timestamp" file, that contains nothing but a
 611          * usec_t timestamp, formatted in ASCII. */
 612
 613         if (n <= 0 || n >= USEC_INFINITY)
 614                 return -ERANGE;
 615
 616         xsprintf(ln, USEC_FMT "\n", n);
 617
 618         return write_string_file(fn, ln, WRITE_STRING_FILE_CREATE|WRITE_STRING_FILE_ATOMIC);
 619 }
 620
 621 int read_timestamp_file(const char *fn, usec_t *ret) {
 622         _cleanup_free_ char *ln = NULL;
 623         uint64_t t;
 624         int r;
 625
 626         r = read_one_line_file(fn, &ln);
 627         if (r < 0)
 628                 return r;
 629
 630         r = safe_atou64(ln, &t);
 631         if (r < 0)
 632                 return r;
 633
 634         if (t <= 0 || t >= (uint64_t) USEC_INFINITY)
 635                 return -ERANGE;
 636
 637         *ret = (usec_t) t;
 638         return 0;
 639 }
 640
 641 int fputs_with_space(FILE *f, const char *s, const char *separator, bool *space) {
 642         int r;
 643
 644         assert(s);
 645
 646         /* Outputs the specified string with fputs(), but optionally prefixes it with a separator. The *space parameter
 647          * when specified shall initially point to a boolean variable initialized to false. It is set to true after the
 648          * first invocation. This call is supposed to be use in loops, where a separator shall be inserted between each
 649          * element, but not before the first one. */
 650
 651         if (!f)
 652                 f = stdout;
 653
 654         if (space) {
 655                 if (!separator)
 656                         separator = " ";
 657
 658                 if (*space) {
 659                         r = fputs(separator, f);
 660                         if (r < 0)
 661                                 return r;
 662                 }
 663
 664                 *space = true;
 665         }
 666
 667         return fputs(s, f);
 668 }
 669
 670 /* A bitmask of the EOL markers we know */
 671 typedef enum EndOfLineMarker {
 672         EOL_NONE     = 0,
 673         EOL_ZERO     = 1 << 0,  /* \0 (aka NUL) */
 674         EOL_TEN      = 1 << 1,  /* \n (aka NL, aka LF)  */
 675         EOL_THIRTEEN = 1 << 2,  /* \r (aka CR)  */
 676 } EndOfLineMarker;
 677
 678 static EndOfLineMarker categorize_eol(char c, ReadLineFlags flags) {
 679
 680         if (!IN_SET(flags, READ_LINE_ONLY_NUL)) {
 681                 if (c == '\n')
 682                         return EOL_TEN;
 683                 if (c == '\r')
 684                         return EOL_THIRTEEN;
 685         }
 686
 687         if (c == '\0')
 688                 return EOL_ZERO;
 689
 690         return EOL_NONE;
 691 }
 692
 693 DEFINE_TRIVIAL_CLEANUP_FUNC(FILE*, funlockfile);
 694
 695 int read_line_full(FILE *f, size_t limit, ReadLineFlags flags, char **ret) {
 696         size_t n = 0, allocated = 0, count = 0;
 697         _cleanup_free_ char *buffer = NULL;
 698         int r;
 699
 700         assert(f);
 701
 702         /* Something like a bounded version of getline().
 703          *
 704          * Considers EOF, \n, \r and \0 end of line delimiters (or combinations of these), and does not include these
 705          * delimiters in the string returned. Specifically, recognizes the following combinations of markers as line
 706          * endings:
 707          *
 708          *     • \n        (UNIX)
 709          *     • \r        (old MacOS)
 710          *     • \0        (C strings)
 711          *     • \n\0
 712          *     • \r\0
 713          *     • \r\n      (Windows)
 714          *     • \n\r
 715          *     • \r\n\0
 716          *     • \n\r\0
 717          *
 718          * Returns the number of bytes read from the files (i.e. including delimiters — this hence usually differs from
 719          * the number of characters in the returned string). When EOF is hit, 0 is returned.
 720          *
 721          * The input parameter limit is the maximum numbers of characters in the returned string, i.e. excluding
 722          * delimiters. If the limit is hit we fail and return -ENOBUFS.
 723          *
 724          * If a line shall be skipped ret may be initialized as NULL. */
 725
 726         if (ret) {
 727                 if (!GREEDY_REALLOC(buffer, allocated, 1))
 728                         return -ENOMEM;
 729         }
 730
 731         {
 732                 _unused_ _cleanup_(funlockfilep) FILE *flocked = f;
 733                 EndOfLineMarker previous_eol = EOL_NONE;
 734                 flockfile(f);
 735
 736                 for (;;) {
 737                         EndOfLineMarker eol;
 738                         char c;
 739
 740                         if (n >= limit)
 741                                 return -ENOBUFS;
 742
 743                         if (count >= INT_MAX) /* We couldn't return the counter anymore as "int", hence refuse this */
 744                                 return -ENOBUFS;
 745
 746                         r = safe_fgetc(f, &c);
 747                         if (r < 0)
 748                                 return r;
 749                         if (r == 0) /* EOF is definitely EOL */
 750                                 break;
 751
 752                         eol = categorize_eol(c, flags);
 753
 754                         if (FLAGS_SET(previous_eol, EOL_ZERO) ||
 755                             (eol == EOL_NONE && previous_eol != EOL_NONE) ||
 756                             (eol != EOL_NONE && (previous_eol & eol) != 0)) {
 757                                 /* Previous char was a NUL? This is not an EOL, but the previous char was? This type of
 758                                  * EOL marker has been seen right before? In either of these three cases we are
 759                                  * done. But first, let's put this character back in the queue. */
 760                                 assert_se(ungetc(c, f) != EOF);
 761                                 break;
 762                         }
 763
 764                         count++;
 765
 766                         if (eol != EOL_NONE) {
 767                                 previous_eol |= eol;
 768                                 continue;
 769                         }
 770
 771                         if (ret) {
 772                                 if (!GREEDY_REALLOC(buffer, allocated, n + 2))
 773                                         return -ENOMEM;
 774
 775                                 buffer[n] = c;
 776                         }
 777
 778                         n++;
 779                 }
 780         }
 781
 782         if (ret) {
 783                 buffer[n] = 0;
 784
 785                 *ret = TAKE_PTR(buffer);
 786         }
 787
 788         return (int) count;
 789 }
 790
 791 int safe_fgetc(FILE *f, char *ret) {
 792         int k;
 793
 794         assert(f);
 795
 796         /* A safer version of plain fgetc(): let's propagate the error that happened while reading as such, and
 797          * separate the EOF condition from the byte read, to avoid those confusion signed/unsigned issues fgetc()
 798          * has. */
 799
 800         errno = 0;
 801         k = fgetc(f);
 802         if (k == EOF) {
 803                 if (ferror(f))
 804                         return errno > 0 ? -errno : -EIO;
 805
 806                 if (ret)
 807                         *ret = 0;
 808
 809                 return 0;
 810         }
 811
 812         if (ret)
 813                 *ret = k;
 814
 815         return 1;
 816 }