1 // Copyright 2023 The ChromiumOS Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 use std::os::unix::io::RawFd;
6
7 use libc::c_int;
8 use libc::fcntl;
9 use libc::F_GETFL;
10 use libc::F_SETFL;
11
12 use crate::errno::Result;
13 use crate::syscall;
14
15 /// Returns the file flags set for the given `RawFD`
16 ///
17 /// Returns an error if the OS indicates the flags can't be retrieved.
get_fd_flags(fd: RawFd) -> Result<c_int>18 fn get_fd_flags(fd: RawFd) -> Result<c_int> {
19 syscall!(
20 // SAFETY:
21 // Safe because no third parameter is expected and we check the return result.
22 unsafe { fcntl(fd, F_GETFL) }
23 )
24 }
25
26 /// Sets the file flags set for the given `RawFD`.
27 ///
28 /// Returns an error if the OS indicates the flags can't be retrieved.
set_fd_flags(fd: RawFd, flags: c_int) -> Result<()>29 fn set_fd_flags(fd: RawFd, flags: c_int) -> Result<()> {
30 syscall!(
31 // SAFETY:
32 // Safe because we supply the third parameter and we check the return result.
33 // fcntlt is trusted not to modify the memory of the calling process.
34 unsafe { fcntl(fd, F_SETFL, flags) }
35 )
36 .map(|_| ())
37 }
38
39 /// Performs a logical OR of the given flags with the FD's flags, setting the given bits for the
40 /// FD.
41 ///
42 /// Returns an error if the OS indicates the flags can't be retrieved or set.
add_fd_flags(fd: RawFd, set_flags: c_int) -> Result<()>43 pub fn add_fd_flags(fd: RawFd, set_flags: c_int) -> Result<()> {
44 let start_flags = get_fd_flags(fd)?;
45 set_fd_flags(fd, start_flags | set_flags)
46 }
47
48 /// Clears the given flags in the FD's flags.
49 ///
50 /// Returns an error if the OS indicates the flags can't be retrieved or set.
clear_fd_flags(fd: RawFd, clear_flags: c_int) -> Result<()>51 pub fn clear_fd_flags(fd: RawFd, clear_flags: c_int) -> Result<()> {
52 let start_flags = get_fd_flags(fd)?;
53 set_fd_flags(fd, start_flags & !clear_flags)
54 }
55