src/unistd/ttyname_r.c

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

void __procfdname(char *, unsigned);

int ttyname_r(int fd, char *name, size_t size)
{
	char procname[sizeof "/proc/self/fd/" + 3*sizeof(int) + 2];
	ssize_t l;

	if (!isatty(fd)) return ENOTTY;

	__procfdname(procname, fd);
	l = readlink(procname, name, size);

	if (l < 0) return errno;
	else if (l == size) return ERANGE;
	else {
		name[l] = 0;
		return 0;
	}
}