glibc/stdlib/mblen.c

69 lines
2.0 KiB
C

/* Copyright (C) 1991-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <stdlib.h>
#include <string.h>
#include <wchar.h>
#include <gconv.h>
#include <wcsmbs/wcsmbsload.h>
/* Internal state. */
static mbstate_t state;
/* Return the length of the multibyte character (if there is one)
at S which is no longer than N characters.
The ISO C standard says that the `mblen' function must not change
the state of the `mbtowc' function. */
int
mblen (const char *s, size_t n)
{
int result;
/* If S is NULL the function has to return null or not null
depending on the encoding having a state depending encoding or
not. */
if (s == NULL)
{
const struct gconv_fcts *fcts;
/* Get the conversion functions. */
fcts = get_gconv_fcts (_NL_CURRENT_DATA (LC_CTYPE));
/* Reset the state. */
memset (&state, '\0', sizeof state);
result = fcts->towc->__stateful;
}
else if (*s == '\0')
/* According to the ISO C 89 standard this is the expected behaviour. */
result = 0;
else
{
memset (&state, '\0', sizeof state);
result = __mbrtowc (NULL, s, n, &state);
/* The `mbrtowc' functions tell us more than we need. Fold the -1
and -2 result into -1. */
if (result < 0)
result = -1;
}
return result;
}