1#include <unistd.h>
2#include <errno.h>
3#include <sys/stat.h>
4
5void __procfdname(char *, unsigned);
6
7int ttyname_r(int fd, char *name, size_t size)
8{
9	struct stat st1, st2;
10	char procname[sizeof "/proc/self/fd/" + 3*sizeof(int) + 2];
11	ssize_t l;
12
13	if (!isatty(fd)) return ENOTTY;
14
15	__procfdname(procname, fd);
16	l = readlink(procname, name, size);
17
18	if (l < 0) return errno;
19	else if (l == size) return ERANGE;
20
21	name[l] = 0;
22
23	if (stat(name, &st1) || fstat(fd, &st2))
24		return errno;
25	if (st1.st_dev != st2.st_dev || st1.st_ino != st2.st_ino)
26		return ENOENT;
27
28	return 0;
29}
30