musl/src/stdio/fgetws.c

#include "stdio_impl.h"
#include <wchar.h>
#include <errno.h>

wint_t __fgetwc_unlocked(FILE *);

wchar_t *fgetws(wchar_t *restrict s, int n, FILE *restrict f)
{
	wchar_t *p = s;

	if (!n--) return s;

	FLOCK(f);

	/* Setup a dummy errno so we can detect EILSEQ. This is
	 * the only way to catch encoding errors in the form of a
	 * partial character just before EOF. */
	errno = EAGAIN;
	for (; n; n--) {
		wint_t c = __fgetwc_unlocked(f);
		if (c == WEOF) break;
		*p++ = c;
		if (c == '\n') break;
	}
	*p = 0;
	if (ferror(f) || errno==EILSEQ) p = s;

	FUNLOCK(f);

	return (p == s) ? NULL : s;
}

weak_alias(fgetws, fgetws_unlocked);