mbsnrtowcs - convert a multibyte string to a wide-character string
dest is not NULL, the mbsnrtowcs() function converts at most
nms bytes from the multibyte string
*src to a wide-character string starting at
dest. At most
len wide characters are written to
dest. The shift state
*ps is updated. The conversion is effectively performed by repeatedly calling
mbrtowc(dest, *src, n, ps) where
n is some positive number, as long as this call succeeds, and then incrementing
dest by one and
*src by the number of bytes consumed. The conversion can stop for three reasons:
An invalid multibyte sequence has been encountered. In this case,
*src is left pointing to the invalid multibyte sequence,
(size_t) -1 is returned, and
errno is set to EILSEQ.
nms limit forces a stop, or
len non-L'\0' wide characters have been stored at
dest. In this case,
*src is left pointing to the next multibyte sequence to be converted, and the number of wide characters written to
dest is returned.
The multibyte string has been completely converted, including the terminating null wide character ('\0') (which has the side effect of bringing back
*ps to the initial state). In this case,
*src is set to NULL, and the number of wide characters written to
dest, excluding the terminating null wide character, is returned.
According to POSIX.1, if the input buffer ends with an incomplete character, it is unspecified whether conversion stops at the end of the previous character (if any), or at the end of the input buffer. The glibc implementation adopts the former behavior.
dest is NULL,
len is ignored, and the conversion proceeds as above, except that the converted wide characters are not written out to memory, and that no destination length limit exists.
In both of the above cases, if
ps is NULL, a static anonymous state known only to the mbsnrtowcs() function is used instead.
The programmer must ensure that there is room for at least
len wide characters at
The behavior of mbsnrtowcs() depends on the LC_CTYPE category of the current locale.
Passing NULL as
ps is not multithread safe.
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