newlib/libc/string/strtok.c

   1 /*
   2 FUNCTION
   3         <<strtok>>, <<strtok_r>>, <<strsep>>---get next token from a string
   4
   5 INDEX
   6         strtok
   7
   8 INDEX
   9         strtok_r
  10
  11 INDEX
  12         strsep
  13
  14 SYNOPSIS
  15         #include <string.h>
  16         char *strtok(char *restrict <[source]>,
  17                      const char *restrict <[delimiters]>);
  18         char *strtok_r(char *restrict <[source]>,
  19                        const char *restrict <[delimiters]>,
  20                        char **<[lasts]>);
  21         char *strsep(char **<[source_ptr]>, const char *<[delimiters]>);
  22
  23 DESCRIPTION
  24         The <<strtok>> function is used to isolate sequential tokens in a
  25         null-terminated string, <<*<[source]>>>. These tokens are delimited
  26         in the string by at least one of the characters in <<*<[delimiters]>>>.
  27         The first time that <<strtok>> is called, <<*<[source]>>> should be
  28         specified; subsequent calls, wishing to obtain further tokens from
  29         the same string, should pass a null pointer instead.  The separator
  30         string, <<*<[delimiters]>>>, must be supplied each time and may
  31         change between calls.
  32
  33         The <<strtok>> function returns a pointer to the beginning of each
  34         subsequent token in the string, after replacing the separator
  35         character itself with a null character.  When no more tokens remain,
  36         a null pointer is returned.
  37
  38         The <<strtok_r>> function has the same behavior as <<strtok>>, except
  39         a pointer to placeholder <<*<[lasts]>>> must be supplied by the caller.
  40
  41         The <<strsep>> function is similar in behavior to <<strtok>>, except
  42         a pointer to the string pointer must be supplied <<<[source_ptr]>>> and
  43         the function does not skip leading delimiters.  When the string starts
  44         with a delimiter, the delimiter is changed to the null character and
  45         the empty string is returned.  Like <<strtok_r>> and <<strtok>>, the
  46         <<*<[source_ptr]>>> is updated to the next character following the
  47         last delimiter found or NULL if the end of string is reached with
  48         no more delimiters.
  49
  50 RETURNS
  51         <<strtok>>, <<strtok_r>>, and <<strsep>> all return a pointer to the
  52         next token, or <<NULL>> if no more tokens can be found.  For
  53         <<strsep>>, a token may be the empty string.
  54
  55 NOTES
  56         <<strtok>> is unsafe for multi-threaded applications.  <<strtok_r>>
  57         and <<strsep>> are thread-safe and should be used instead.
  58
  59 PORTABILITY
  60 <<strtok>> is ANSI C.
  61 <<strtok_r>> is POSIX.
  62 <<strsep>> is a BSD extension.
  63
  64 <<strtok>>, <<strtok_r>>, and <<strsep>> require no supporting OS subroutines.
  65
  66 QUICKREF
  67         strtok ansi impure
  68 */
  69
  70 /* undef STRICT_ANSI so that strtok_r prototype will be defined */
  71 #undef  __STRICT_ANSI__
  72 #include <string.h>
  73 #include <stdlib.h>
  74 #include <_ansi.h>
  75 #include <reent.h>
  76
  77 #ifdef _REENT_THREAD_LOCAL
  78 _Thread_local char *_tls_strtok_last;
  79 #endif
  80
  81 #ifndef _REENT_ONLY
  82
  83 extern char *__strtok_r (char *, const char *, char **, int);
  84
  85 char *
  86 strtok (register char *__restrict s,
  87         register const char *__restrict delim)
  88 {
  89         struct _reent *reent = _REENT;
  90
  91         _REENT_CHECK_MISC(reent);
  92         return __strtok_r (s, delim, &(_REENT_STRTOK_LAST(reent)), 1);
  93 }
  94 #endif