rework langinfo code for ABI compat and for use by time code

[musl] / src / unistd / ttyname.c

#include <unistd.h>
#include <errno.h>
#include <limits.h>

char *ttyname(int fd)
{
        static char buf[TTY_NAME_MAX];
        int result;
        if ((result = ttyname_r(fd, buf, sizeof buf))) {
                errno = result;
                return NULL;
        }
        return buf;
}