lib/string.in.h

   1 /* A GNU-like <string.h>.
   2
   3    Copyright (C) 1995-1996, 2001-2009 Free Software Foundation, Inc.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU Lesser General Public License as published by
   7    the Free Software Foundation; either version 2, or (at your option)
   8    any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public License
  16    along with this program; if not, write to the Free Software Foundation,
  17    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  18
  19 #ifndef _GL_STRING_H
  20
  21 #if __GNUC__ >= 3
  22 @PRAGMA_SYSTEM_HEADER@
  23 #endif
  24
  25 /* The include_next requires a split double-inclusion guard.  */
  26 #@INCLUDE_NEXT@ @NEXT_STRING_H@
  27
  28 #ifndef _GL_STRING_H
  29 #define _GL_STRING_H
  30
  31
  32 #ifndef __attribute__
  33 /* This feature is available in gcc versions 2.5 and later.  */
  34 # if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 5)
  35 #  define __attribute__(Spec) /* empty */
  36 # endif
  37 /* The attribute __pure__ was added in gcc 2.96.  */
  38 # if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 96)
  39 #  define __pure__ /* empty */
  40 # endif
  41 #endif
  42
  43
  44 /* The definition of GL_LINK_WARNING is copied here.  */
  45
  46
  47 #ifdef __cplusplus
  48 extern "C" {
  49 #endif
  50
  51
  52 /* Return the first instance of C within N bytes of S, or NULL.  */
  53 #if @GNULIB_MEMCHR@
  54 # if @REPLACE_MEMCHR@
  55 #  define memchr rpl_memchr
  56 extern void *memchr (void const *__s, int __c, size_t __n)
  57   __attribute__ ((__pure__));
  58 # endif
  59 #elif defined GNULIB_POSIXCHECK
  60 # undef memchr
  61 # define memchr(s,c,n) \
  62     (GL_LINK_WARNING ("memchr has platform-specific bugs - " \
  63                       "use gnulib module memchr for portability" ), \
  64      memchr (s, c, n))
  65 #endif
  66
  67 /* Return the first occurrence of NEEDLE in HAYSTACK.  */
  68 #if @GNULIB_MEMMEM@
  69 # if @REPLACE_MEMMEM@
  70 #  define memmem rpl_memmem
  71 # endif
  72 # if ! @HAVE_DECL_MEMMEM@ || @REPLACE_MEMMEM@
  73 extern void *memmem (void const *__haystack, size_t __haystack_len,
  74                      void const *__needle, size_t __needle_len)
  75   __attribute__ ((__pure__));
  76 # endif
  77 #elif defined GNULIB_POSIXCHECK
  78 # undef memmem
  79 # define memmem(a,al,b,bl) \
  80     (GL_LINK_WARNING ("memmem is unportable and often quadratic - " \
  81                       "use gnulib module memmem-simple for portability, " \
  82                       "and module memmem for speed" ), \
  83      memmem (a, al, b, bl))
  84 #endif
  85
  86 /* Copy N bytes of SRC to DEST, return pointer to bytes after the
  87    last written byte.  */
  88 #if @GNULIB_MEMPCPY@
  89 # if ! @HAVE_MEMPCPY@
  90 extern void *mempcpy (void *restrict __dest, void const *restrict __src,
  91                       size_t __n);
  92 # endif
  93 #elif defined GNULIB_POSIXCHECK
  94 # undef mempcpy
  95 # define mempcpy(a,b,n) \
  96     (GL_LINK_WARNING ("mempcpy is unportable - " \
  97                       "use gnulib module mempcpy for portability"), \
  98      mempcpy (a, b, n))
  99 #endif
 100
 101 /* Search backwards through a block for a byte (specified as an int).  */
 102 #if @GNULIB_MEMRCHR@
 103 # if ! @HAVE_DECL_MEMRCHR@
 104 extern void *memrchr (void const *, int, size_t)
 105   __attribute__ ((__pure__));
 106 # endif
 107 #elif defined GNULIB_POSIXCHECK
 108 # undef memrchr
 109 # define memrchr(a,b,c) \
 110     (GL_LINK_WARNING ("memrchr is unportable - " \
 111                       "use gnulib module memrchr for portability"), \
 112      memrchr (a, b, c))
 113 #endif
 114
 115 /* Find the first occurrence of C in S.  More efficient than
 116    memchr(S,C,N), at the expense of undefined behavior if C does not
 117    occur within N bytes.  */
 118 #if @GNULIB_RAWMEMCHR@
 119 # if ! @HAVE_RAWMEMCHR@
 120 extern void *rawmemchr (void const *__s, int __c_in)
 121   __attribute__ ((__pure__));
 122 # endif
 123 #elif defined GNULIB_POSIXCHECK
 124 # undef rawmemchr
 125 # define rawmemchr(a,b) \
 126     (GL_LINK_WARNING ("rawmemchr is unportable - " \
 127                       "use gnulib module rawmemchr for portability"), \
 128      rawmemchr (a, b))
 129 #endif
 130
 131 /* Copy SRC to DST, returning the address of the terminating '\0' in DST.  */
 132 #if @GNULIB_STPCPY@
 133 # if ! @HAVE_STPCPY@
 134 extern char *stpcpy (char *restrict __dst, char const *restrict __src);
 135 # endif
 136 #elif defined GNULIB_POSIXCHECK
 137 # undef stpcpy
 138 # define stpcpy(a,b) \
 139     (GL_LINK_WARNING ("stpcpy is unportable - " \
 140                       "use gnulib module stpcpy for portability"), \
 141      stpcpy (a, b))
 142 #endif
 143
 144 /* Copy no more than N bytes of SRC to DST, returning a pointer past the
 145    last non-NUL byte written into DST.  */
 146 #if @GNULIB_STPNCPY@
 147 # if ! @HAVE_STPNCPY@
 148 #  define stpncpy gnu_stpncpy
 149 extern char *stpncpy (char *restrict __dst, char const *restrict __src,
 150                       size_t __n);
 151 # endif
 152 #elif defined GNULIB_POSIXCHECK
 153 # undef stpncpy
 154 # define stpncpy(a,b,n) \
 155     (GL_LINK_WARNING ("stpncpy is unportable - " \
 156                       "use gnulib module stpncpy for portability"), \
 157      stpncpy (a, b, n))
 158 #endif
 159
 160 #if defined GNULIB_POSIXCHECK
 161 /* strchr() does not work with multibyte strings if the locale encoding is
 162    GB18030 and the character to be searched is a digit.  */
 163 # undef strchr
 164 # define strchr(s,c) \
 165     (GL_LINK_WARNING ("strchr cannot work correctly on character strings " \
 166                       "in some multibyte locales - " \
 167                       "use mbschr if you care about internationalization"), \
 168      strchr (s, c))
 169 #endif
 170
 171 /* Find the first occurrence of C in S or the final NUL byte.  */
 172 #if @GNULIB_STRCHRNUL@
 173 # if ! @HAVE_STRCHRNUL@
 174 extern char *strchrnul (char const *__s, int __c_in)
 175   __attribute__ ((__pure__));
 176 # endif
 177 #elif defined GNULIB_POSIXCHECK
 178 # undef strchrnul
 179 # define strchrnul(a,b) \
 180     (GL_LINK_WARNING ("strchrnul is unportable - " \
 181                       "use gnulib module strchrnul for portability"), \
 182      strchrnul (a, b))
 183 #endif
 184
 185 /* Duplicate S, returning an identical malloc'd string.  */
 186 #if @GNULIB_STRDUP@
 187 # if @REPLACE_STRDUP@
 188 #  undef strdup
 189 #  define strdup rpl_strdup
 190 # endif
 191 # if !(@HAVE_DECL_STRDUP@ || defined strdup) || @REPLACE_STRDUP@
 192 extern char *strdup (char const *__s);
 193 # endif
 194 #elif defined GNULIB_POSIXCHECK
 195 # undef strdup
 196 # define strdup(a) \
 197     (GL_LINK_WARNING ("strdup is unportable - " \
 198                       "use gnulib module strdup for portability"), \
 199      strdup (a))
 200 #endif
 201
 202 /* Return a newly allocated copy of at most N bytes of STRING.  */
 203 #if @GNULIB_STRNDUP@
 204 # if ! @HAVE_STRNDUP@
 205 #  undef strndup
 206 #  define strndup rpl_strndup
 207 # endif
 208 # if ! @HAVE_STRNDUP@ || ! @HAVE_DECL_STRNDUP@
 209 extern char *strndup (char const *__string, size_t __n);
 210 # endif
 211 #elif defined GNULIB_POSIXCHECK
 212 # undef strndup
 213 # define strndup(a,n) \
 214     (GL_LINK_WARNING ("strndup is unportable - " \
 215                       "use gnulib module strndup for portability"), \
 216      strndup (a, n))
 217 #endif
 218
 219 /* Find the length (number of bytes) of STRING, but scan at most
 220    MAXLEN bytes.  If no '\0' terminator is found in that many bytes,
 221    return MAXLEN.  */
 222 #if @GNULIB_STRNLEN@
 223 # if ! @HAVE_DECL_STRNLEN@
 224 extern size_t strnlen (char const *__string, size_t __maxlen)
 225   __attribute__ ((__pure__));
 226 # endif
 227 #elif defined GNULIB_POSIXCHECK
 228 # undef strnlen
 229 # define strnlen(a,n) \
 230     (GL_LINK_WARNING ("strnlen is unportable - " \
 231                       "use gnulib module strnlen for portability"), \
 232      strnlen (a, n))
 233 #endif
 234
 235 #if defined GNULIB_POSIXCHECK
 236 /* strcspn() assumes the second argument is a list of single-byte characters.
 237    Even in this simple case, it does not work with multibyte strings if the
 238    locale encoding is GB18030 and one of the characters to be searched is a
 239    digit.  */
 240 # undef strcspn
 241 # define strcspn(s,a) \
 242     (GL_LINK_WARNING ("strcspn cannot work correctly on character strings " \
 243                       "in multibyte locales - " \
 244                       "use mbscspn if you care about internationalization"), \
 245      strcspn (s, a))
 246 #endif
 247
 248 /* Find the first occurrence in S of any character in ACCEPT.  */
 249 #if @GNULIB_STRPBRK@
 250 # if ! @HAVE_STRPBRK@
 251 extern char *strpbrk (char const *__s, char const *__accept)
 252   __attribute__ ((__pure__));
 253 # endif
 254 # if defined GNULIB_POSIXCHECK
 255 /* strpbrk() assumes the second argument is a list of single-byte characters.
 256    Even in this simple case, it does not work with multibyte strings if the
 257    locale encoding is GB18030 and one of the characters to be searched is a
 258    digit.  */
 259 #  undef strpbrk
 260 #  define strpbrk(s,a) \
 261      (GL_LINK_WARNING ("strpbrk cannot work correctly on character strings " \
 262                        "in multibyte locales - " \
 263                        "use mbspbrk if you care about internationalization"), \
 264       strpbrk (s, a))
 265 # endif
 266 #elif defined GNULIB_POSIXCHECK
 267 # undef strpbrk
 268 # define strpbrk(s,a) \
 269     (GL_LINK_WARNING ("strpbrk is unportable - " \
 270                       "use gnulib module strpbrk for portability"), \
 271      strpbrk (s, a))
 272 #endif
 273
 274 #if defined GNULIB_POSIXCHECK
 275 /* strspn() assumes the second argument is a list of single-byte characters.
 276    Even in this simple case, it cannot work with multibyte strings.  */
 277 # undef strspn
 278 # define strspn(s,a) \
 279     (GL_LINK_WARNING ("strspn cannot work correctly on character strings " \
 280                       "in multibyte locales - " \
 281                       "use mbsspn if you care about internationalization"), \
 282      strspn (s, a))
 283 #endif
 284
 285 #if defined GNULIB_POSIXCHECK
 286 /* strrchr() does not work with multibyte strings if the locale encoding is
 287    GB18030 and the character to be searched is a digit.  */
 288 # undef strrchr
 289 # define strrchr(s,c) \
 290     (GL_LINK_WARNING ("strrchr cannot work correctly on character strings " \
 291                       "in some multibyte locales - " \
 292                       "use mbsrchr if you care about internationalization"), \
 293      strrchr (s, c))
 294 #endif
 295
 296 /* Search the next delimiter (char listed in DELIM) starting at *STRINGP.
 297    If one is found, overwrite it with a NUL, and advance *STRINGP
 298    to point to the next char after it.  Otherwise, set *STRINGP to NULL.
 299    If *STRINGP was already NULL, nothing happens.
 300    Return the old value of *STRINGP.
 301
 302    This is a variant of strtok() that is multithread-safe and supports
 303    empty fields.
 304
 305    Caveat: It modifies the original string.
 306    Caveat: These functions cannot be used on constant strings.
 307    Caveat: The identity of the delimiting character is lost.
 308    Caveat: It doesn't work with multibyte strings unless all of the delimiter
 309            characters are ASCII characters < 0x30.
 310
 311    See also strtok_r().  */
 312 #if @GNULIB_STRSEP@
 313 # if ! @HAVE_STRSEP@
 314 extern char *strsep (char **restrict __stringp, char const *restrict __delim);
 315 # endif
 316 # if defined GNULIB_POSIXCHECK
 317 #  undef strsep
 318 #  define strsep(s,d) \
 319      (GL_LINK_WARNING ("strsep cannot work correctly on character strings " \
 320                        "in multibyte locales - " \
 321                        "use mbssep if you care about internationalization"), \
 322       strsep (s, d))
 323 # endif
 324 #elif defined GNULIB_POSIXCHECK
 325 # undef strsep
 326 # define strsep(s,d) \
 327     (GL_LINK_WARNING ("strsep is unportable - " \
 328                       "use gnulib module strsep for portability"), \
 329      strsep (s, d))
 330 #endif
 331
 332 #if @GNULIB_STRSTR@
 333 # if @REPLACE_STRSTR@
 334 #  define strstr rpl_strstr
 335 char *strstr (const char *haystack, const char *needle)
 336   __attribute__ ((__pure__));
 337 # endif
 338 #elif defined GNULIB_POSIXCHECK
 339 /* strstr() does not work with multibyte strings if the locale encoding is
 340    different from UTF-8:
 341    POSIX says that it operates on "strings", and "string" in POSIX is defined
 342    as a sequence of bytes, not of characters.  */
 343 # undef strstr
 344 # define strstr(a,b) \
 345     (GL_LINK_WARNING ("strstr is quadratic on many systems, and cannot " \
 346                       "work correctly on character strings in most "    \
 347                       "multibyte locales - " \
 348                       "use mbsstr if you care about internationalization, " \
 349                       "or use strstr if you care about speed"), \
 350      strstr (a, b))
 351 #endif
 352
 353 /* Find the first occurrence of NEEDLE in HAYSTACK, using case-insensitive
 354    comparison.  */
 355 #if @GNULIB_STRCASESTR@
 356 # if @REPLACE_STRCASESTR@
 357 #  define strcasestr rpl_strcasestr
 358 # endif
 359 # if ! @HAVE_STRCASESTR@ || @REPLACE_STRCASESTR@
 360 extern char *strcasestr (const char *haystack, const char *needle)
 361   __attribute__ ((__pure__));
 362 # endif
 363 #elif defined GNULIB_POSIXCHECK
 364 /* strcasestr() does not work with multibyte strings:
 365    It is a glibc extension, and glibc implements it only for unibyte
 366    locales.  */
 367 # undef strcasestr
 368 # define strcasestr(a,b) \
 369     (GL_LINK_WARNING ("strcasestr does work correctly on character strings " \
 370                       "in multibyte locales - " \
 371                       "use mbscasestr if you care about " \
 372                       "internationalization, or use c-strcasestr if you want " \
 373                       "a locale independent function"), \
 374      strcasestr (a, b))
 375 #endif
 376
 377 /* Parse S into tokens separated by characters in DELIM.
 378    If S is NULL, the saved pointer in SAVE_PTR is used as
 379    the next starting point.  For example:
 380         char s[] = "-abc-=-def";
 381         char *sp;
 382         x = strtok_r(s, "-", &sp);      // x = "abc", sp = "=-def"
 383         x = strtok_r(NULL, "-=", &sp);  // x = "def", sp = NULL
 384         x = strtok_r(NULL, "=", &sp);   // x = NULL
 385                 // s = "abc\0-def\0"
 386
 387    This is a variant of strtok() that is multithread-safe.
 388
 389    For the POSIX documentation for this function, see:
 390    http://www.opengroup.org/susv3xsh/strtok.html
 391
 392    Caveat: It modifies the original string.
 393    Caveat: These functions cannot be used on constant strings.
 394    Caveat: The identity of the delimiting character is lost.
 395    Caveat: It doesn't work with multibyte strings unless all of the delimiter
 396            characters are ASCII characters < 0x30.
 397
 398    See also strsep().  */
 399 #if @GNULIB_STRTOK_R@
 400 # if ! @HAVE_DECL_STRTOK_R@
 401 extern char *strtok_r (char *restrict s, char const *restrict delim,
 402                        char **restrict save_ptr);
 403 # endif
 404 # if defined GNULIB_POSIXCHECK
 405 #  undef strtok_r
 406 #  define strtok_r(s,d,p) \
 407      (GL_LINK_WARNING ("strtok_r cannot work correctly on character strings " \
 408                        "in multibyte locales - " \
 409                        "use mbstok_r if you care about internationalization"), \
 410       strtok_r (s, d, p))
 411 # endif
 412 #elif defined GNULIB_POSIXCHECK
 413 # undef strtok_r
 414 # define strtok_r(s,d,p) \
 415     (GL_LINK_WARNING ("strtok_r is unportable - " \
 416                       "use gnulib module strtok_r for portability"), \
 417      strtok_r (s, d, p))
 418 #endif
 419
 420
 421 /* The following functions are not specified by POSIX.  They are gnulib
 422    extensions.  */
 423
 424 #if @GNULIB_MBSLEN@
 425 /* Return the number of multibyte characters in the character string STRING.
 426    This considers multibyte characters, unlike strlen, which counts bytes.  */
 427 extern size_t mbslen (const char *string);
 428 #endif
 429
 430 #if @GNULIB_MBSNLEN@
 431 /* Return the number of multibyte characters in the character string starting
 432    at STRING and ending at STRING + LEN.  */
 433 extern size_t mbsnlen (const char *string, size_t len);
 434 #endif
 435
 436 #if @GNULIB_MBSCHR@
 437 /* Locate the first single-byte character C in the character string STRING,
 438    and return a pointer to it.  Return NULL if C is not found in STRING.
 439    Unlike strchr(), this function works correctly in multibyte locales with
 440    encodings such as GB18030.  */
 441 # define mbschr rpl_mbschr /* avoid collision with HP-UX function */
 442 extern char * mbschr (const char *string, int c);
 443 #endif
 444
 445 #if @GNULIB_MBSRCHR@
 446 /* Locate the last single-byte character C in the character string STRING,
 447    and return a pointer to it.  Return NULL if C is not found in STRING.
 448    Unlike strrchr(), this function works correctly in multibyte locales with
 449    encodings such as GB18030.  */
 450 # define mbsrchr rpl_mbsrchr /* avoid collision with HP-UX function */
 451 extern char * mbsrchr (const char *string, int c);
 452 #endif
 453
 454 #if @GNULIB_MBSSTR@
 455 /* Find the first occurrence of the character string NEEDLE in the character
 456    string HAYSTACK.  Return NULL if NEEDLE is not found in HAYSTACK.
 457    Unlike strstr(), this function works correctly in multibyte locales with
 458    encodings different from UTF-8.  */
 459 extern char * mbsstr (const char *haystack, const char *needle);
 460 #endif
 461
 462 #if @GNULIB_MBSCASECMP@
 463 /* Compare the character strings S1 and S2, ignoring case, returning less than,
 464    equal to or greater than zero if S1 is lexicographically less than, equal to
 465    or greater than S2.
 466    Note: This function may, in multibyte locales, return 0 for strings of
 467    different lengths!
 468    Unlike strcasecmp(), this function works correctly in multibyte locales.  */
 469 extern int mbscasecmp (const char *s1, const char *s2);
 470 #endif
 471
 472 #if @GNULIB_MBSNCASECMP@
 473 /* Compare the initial segment of the character string S1 consisting of at most
 474    N characters with the initial segment of the character string S2 consisting
 475    of at most N characters, ignoring case, returning less than, equal to or
 476    greater than zero if the initial segment of S1 is lexicographically less
 477    than, equal to or greater than the initial segment of S2.
 478    Note: This function may, in multibyte locales, return 0 for initial segments
 479    of different lengths!
 480    Unlike strncasecmp(), this function works correctly in multibyte locales.
 481    But beware that N is not a byte count but a character count!  */
 482 extern int mbsncasecmp (const char *s1, const char *s2, size_t n);
 483 #endif
 484
 485 #if @GNULIB_MBSPCASECMP@
 486 /* Compare the initial segment of the character string STRING consisting of
 487    at most mbslen (PREFIX) characters with the character string PREFIX,
 488    ignoring case, returning less than, equal to or greater than zero if this
 489    initial segment is lexicographically less than, equal to or greater than
 490    PREFIX.
 491    Note: This function may, in multibyte locales, return 0 if STRING is of
 492    smaller length than PREFIX!
 493    Unlike strncasecmp(), this function works correctly in multibyte
 494    locales.  */
 495 extern char * mbspcasecmp (const char *string, const char *prefix);
 496 #endif
 497
 498 #if @GNULIB_MBSCASESTR@
 499 /* Find the first occurrence of the character string NEEDLE in the character
 500    string HAYSTACK, using case-insensitive comparison.
 501    Note: This function may, in multibyte locales, return success even if
 502    strlen (haystack) < strlen (needle) !
 503    Unlike strcasestr(), this function works correctly in multibyte locales.  */
 504 extern char * mbscasestr (const char *haystack, const char *needle);
 505 #endif
 506
 507 #if @GNULIB_MBSCSPN@
 508 /* Find the first occurrence in the character string STRING of any character
 509    in the character string ACCEPT.  Return the number of bytes from the
 510    beginning of the string to this occurrence, or to the end of the string
 511    if none exists.
 512    Unlike strcspn(), this function works correctly in multibyte locales.  */
 513 extern size_t mbscspn (const char *string, const char *accept);
 514 #endif
 515
 516 #if @GNULIB_MBSPBRK@
 517 /* Find the first occurrence in the character string STRING of any character
 518    in the character string ACCEPT.  Return the pointer to it, or NULL if none
 519    exists.
 520    Unlike strpbrk(), this function works correctly in multibyte locales.  */
 521 # define mbspbrk rpl_mbspbrk /* avoid collision with HP-UX function */
 522 extern char * mbspbrk (const char *string, const char *accept);
 523 #endif
 524
 525 #if @GNULIB_MBSSPN@
 526 /* Find the first occurrence in the character string STRING of any character
 527    not in the character string REJECT.  Return the number of bytes from the
 528    beginning of the string to this occurrence, or to the end of the string
 529    if none exists.
 530    Unlike strspn(), this function works correctly in multibyte locales.  */
 531 extern size_t mbsspn (const char *string, const char *reject);
 532 #endif
 533
 534 #if @GNULIB_MBSSEP@
 535 /* Search the next delimiter (multibyte character listed in the character
 536    string DELIM) starting at the character string *STRINGP.
 537    If one is found, overwrite it with a NUL, and advance *STRINGP to point
 538    to the next multibyte character after it.  Otherwise, set *STRINGP to NULL.
 539    If *STRINGP was already NULL, nothing happens.
 540    Return the old value of *STRINGP.
 541
 542    This is a variant of mbstok_r() that supports empty fields.
 543
 544    Caveat: It modifies the original string.
 545    Caveat: These functions cannot be used on constant strings.
 546    Caveat: The identity of the delimiting character is lost.
 547
 548    See also mbstok_r().  */
 549 extern char * mbssep (char **stringp, const char *delim);
 550 #endif
 551
 552 #if @GNULIB_MBSTOK_R@
 553 /* Parse the character string STRING into tokens separated by characters in
 554    the character string DELIM.
 555    If STRING is NULL, the saved pointer in SAVE_PTR is used as
 556    the next starting point.  For example:
 557         char s[] = "-abc-=-def";
 558         char *sp;
 559         x = mbstok_r(s, "-", &sp);      // x = "abc", sp = "=-def"
 560         x = mbstok_r(NULL, "-=", &sp);  // x = "def", sp = NULL
 561         x = mbstok_r(NULL, "=", &sp);   // x = NULL
 562                 // s = "abc\0-def\0"
 563
 564    Caveat: It modifies the original string.
 565    Caveat: These functions cannot be used on constant strings.
 566    Caveat: The identity of the delimiting character is lost.
 567
 568    See also mbssep().  */
 569 extern char * mbstok_r (char *string, const char *delim, char **save_ptr);
 570 #endif
 571
 572 /* Map any int, typically from errno, into an error message.  */
 573 #if @GNULIB_STRERROR@
 574 # if @REPLACE_STRERROR@
 575 #  undef strerror
 576 #  define strerror rpl_strerror
 577 extern char *strerror (int);
 578 # endif
 579 #elif defined GNULIB_POSIXCHECK
 580 # undef strerror
 581 # define strerror(e) \
 582     (GL_LINK_WARNING ("strerror is unportable - " \
 583                       "use gnulib module strerror to guarantee non-NULL result"), \
 584      strerror (e))
 585 #endif
 586
 587 #if @GNULIB_STRSIGNAL@
 588 # if @REPLACE_STRSIGNAL@
 589 #  define strsignal rpl_strsignal
 590 # endif
 591 # if ! @HAVE_DECL_STRSIGNAL@ || @REPLACE_STRSIGNAL@
 592 extern char *strsignal (int __sig);
 593 # endif
 594 #elif defined GNULIB_POSIXCHECK
 595 # undef strsignal
 596 # define strsignal(a) \
 597     (GL_LINK_WARNING ("strsignal is unportable - " \
 598                       "use gnulib module strsignal for portability"), \
 599      strsignal (a))
 600 #endif
 601
 602 #if @GNULIB_STRVERSCMP@
 603 # if !@HAVE_STRVERSCMP@
 604 extern int strverscmp (const char *, const char *);
 605 # endif
 606 #elif defined GNULIB_POSIXCHECK
 607 # undef strverscmp
 608 # define strverscmp(a, b) \
 609     (GL_LINK_WARNING ("strverscmp is unportable - " \
 610                       "use gnulib module strverscmp for portability"), \
 611      strverscmp (a, b))
 612 #endif
 613
 614
 615 #ifdef __cplusplus
 616 }
 617 #endif
 618
 619 #endif /* _GL_STRING_H */
 620 #endif /* _GL_STRING_H */