1#include <sys/stat.h>
2#include <fcntl.h>
3#include <errno.h>
4#include "syscall.h"
5
6void __procfdname(char *, unsigned);
7
8int fchmodat(int fd, const char *path, mode_t mode, int flag)
9{
10	if (!flag) return syscall(SYS_fchmodat, fd, path, mode, flag);
11
12	if (flag != AT_SYMLINK_NOFOLLOW)
13		return __syscall_ret(-EINVAL);
14
15	struct stat st;
16	int ret, fd2;
17	char proc[15+3*sizeof(int)];
18
19	if ((ret = __syscall(SYS_fstatat, fd, path, &st, flag)))
20		return __syscall_ret(ret);
21	if (S_ISLNK(st.st_mode))
22		return __syscall_ret(-EOPNOTSUPP);
23
24	if ((fd2 = __syscall(SYS_openat, fd, path, O_RDONLY|O_PATH|O_NOFOLLOW|O_NOCTTY|O_CLOEXEC)) < 0) {
25		if (fd2 == -ELOOP)
26			return __syscall_ret(-EOPNOTSUPP);
27		return __syscall_ret(fd2);
28	}
29
30	__procfdname(proc, fd2);
31	ret = __syscall(SYS_fstatat, AT_FDCWD, proc, &st, 0);
32	if (!ret) {
33		if (S_ISLNK(st.st_mode)) ret = -EOPNOTSUPP;
34		else ret = __syscall(SYS_fchmodat, AT_FDCWD, proc, mode);
35	}
36
37	__syscall(SYS_close, fd2);
38	return __syscall_ret(ret);
39}
40