1#include <unistd.h>
 2#include <errno.h>
 3#include <sys/stat.h>
 4#include "syscall.h"
 5
 6int ttyname_r(int fd, char *name, size_t size)
 7{
 8	struct stat st1, st2;
 9	char procname[sizeof "/proc/self/fd/" + 3*sizeof(int) + 2];
10	ssize_t l;
11
12	if (!isatty(fd)) return errno;
13
14	__procfdname(procname, fd);
15	l = readlink(procname, name, size);
16
17	if (l < 0) return errno;
18	else if (l == size) return ERANGE;
19
20	name[l] = 0;
21
22	if (stat(name, &st1) || fstat(fd, &st2))
23		return errno;
24	if (st1.st_dev != st2.st_dev || st1.st_ino != st2.st_ino)
25		return ENODEV;
26
27	return 0;
28}