newlib/libc/stdlib/mblen.c

   1 /*
   2 FUNCTION
   3 <<mblen>>---minimal multibyte length function
   4
   5 INDEX
   6         mblen
   7
   8 SYNOPSIS
   9         #include <stdlib.h>
  10         int mblen(const char *<[s]>, size_t <[n]>);
  11
  12 DESCRIPTION
  13 When _MB_CAPABLE is not defined, this is a minimal ANSI-conforming
  14 implementation of <<mblen>>.  In this case, the
  15 only ``multi-byte character sequences'' recognized are single bytes,
  16 and thus <<1>> is returned unless <[s]> is the null pointer or
  17 has a length of 0 or is the empty string.
  18
  19 When _MB_CAPABLE is defined, this routine calls <<_mbtowc_r>> to perform
  20 the conversion, passing a state variable to allow state dependent
  21 decoding.  The result is based on the locale setting which may
  22 be restricted to a defined set of locales.
  23
  24 RETURNS
  25 This implementation of <<mblen>> returns <<0>> if
  26 <[s]> is <<NULL>> or the empty string; it returns <<1>> if not _MB_CAPABLE or
  27 the character is a single-byte character; it returns <<-1>>
  28 if the multi-byte character is invalid; otherwise it returns
  29 the number of bytes in the multibyte character.
  30
  31 PORTABILITY
  32 <<mblen>> is required in the ANSI C standard.  However, the precise
  33 effects vary with the locale.
  34
  35 <<mblen>> requires no supporting OS subroutines.
  36 */
  37
  38 #ifndef _REENT_ONLY
  39
  40 #include <newlib.h>
  41 #include <stdlib.h>
  42 #include <wchar.h>
  43 #include "local.h"
  44
  45 #ifdef _REENT_THREAD_LOCAL
  46 _Thread_local _mbstate_t _tls_mblen_state;
  47 #endif
  48
  49 int
  50 mblen (const char *s,
  51         size_t n)
  52 {
  53 #ifdef _MB_CAPABLE
  54   int retval = 0;
  55   struct _reent *reent = _REENT;
  56   mbstate_t *state;
  57
  58   _REENT_CHECK_MISC(reent);
  59   state = &(_REENT_MBLEN_STATE(reent));
  60   retval = __MBTOWC (reent, NULL, s, n, state);
  61   if (retval < 0)
  62     {
  63       state->__count = 0;
  64       return -1;
  65     }
  66   else
  67     return retval;
  68
  69 #else /* not _MB_CAPABLE */
  70   if (s == NULL || *s == '\0')
  71     return 0;
  72   if (n == 0)
  73     return -1;
  74   return 1;
  75 #endif /* not _MB_CAPABLE */
  76 }
  77
  78 #endif /* !_REENT_ONLY */