newlib/libc/stdlib/mblen_r.c

   1 /*
   2 FUNCTION
   3 <<_mblen_r>>---reentrant minimal multibyte length function
   4
   5 INDEX
   6         _mblen_r
   7
   8 SYNOPSIS
   9         #include <stdlib.h>
  10         int _mblen_r(struct _reent *<[r]>, const char *<[s]>, size_t <[n]>, int *<[state]>);
  11
  12 DESCRIPTION
  13 When _MB_CAPABLE is not defined, this is a minimal ANSI-conforming
  14 implementation of <<_mblen_r>>.  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_r>> 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_r>> requires no supporting OS subroutines.
  36 */
  37
  38 #include <newlib.h>
  39 #include <stdlib.h>
  40 #include <wchar.h>
  41 #include "local.h"
  42
  43 int
  44 _mblen_r (struct _reent *r,
  45         const char *s,
  46         size_t n,
  47         mbstate_t *state)
  48 {
  49 #ifdef _MB_CAPABLE
  50   int retval;
  51   retval = __MBTOWC (r, NULL, s, n, state);
  52
  53   if (retval < 0)
  54     {
  55       state->__count = 0;
  56       return -1;
  57     }
  58
  59   return retval;
  60 #else /* not _MB_CAPABLE */
  61   if (s == NULL || *s == '\0')
  62     return 0;
  63   if (n == 0)
  64     return -1;
  65   return 1;
  66 #endif /* not _MB_CAPABLE */
  67 }
  68