}
}
+ #[cfg(target_os = "linux")]
+ pub fn get_cloexec(&self) -> io::Result<bool> {
+ unsafe {
+ Ok((cvt(libc::fcntl(self.fd, libc::F_GETFD))? & libc::FD_CLOEXEC) != 0)
+ }
+ }
+
#[cfg(not(any(target_env = "newlib",
target_os = "solaris",
target_os = "emscripten",
// Currently the standard library supports Linux 2.6.18 which did not
// have the O_CLOEXEC flag (passed above). If we're running on an older
- // Linux kernel then the flag is just ignored by the OS, so we continue
- // to explicitly ask for a CLOEXEC fd here.
+ // Linux kernel then the flag is just ignored by the OS. After we open
+ // the first file, we check whether it has CLOEXEC set. If it doesn't,
+ // we will explicitly ask for a CLOEXEC fd for every further file we
+ // open, if it does, we will skip that step.
//
// The CLOEXEC flag, however, is supported on versions of macOS/BSD/etc
// that we support, so we only do this on Linux currently.
- if cfg!(target_os = "linux") {
- fd.set_cloexec()?;
+ #[cfg(target_os = "linux")]
+ fn ensure_cloexec(fd: &FileDesc) -> io::Result<()> {
+ use sync::atomic::{AtomicUsize, Ordering};
+
+ const OPEN_CLOEXEC_UNKNOWN: usize = 0;
+ const OPEN_CLOEXEC_SUPPORTED: usize = 1;
+ const OPEN_CLOEXEC_NOTSUPPORTED: usize = 2;
+ static OPEN_CLOEXEC: AtomicUsize = AtomicUsize::new(OPEN_CLOEXEC_UNKNOWN);
+
+ let need_to_set;
+ match OPEN_CLOEXEC.load(Ordering::Relaxed) {
+ OPEN_CLOEXEC_UNKNOWN => {
+ need_to_set = !fd.get_cloexec()?;
+ OPEN_CLOEXEC.store(if need_to_set {
+ OPEN_CLOEXEC_NOTSUPPORTED
+ } else {
+ OPEN_CLOEXEC_SUPPORTED
+ }, Ordering::Relaxed);
+ },
+ OPEN_CLOEXEC_SUPPORTED => need_to_set = false,
+ OPEN_CLOEXEC_NOTSUPPORTED => need_to_set = true,
+ _ => unreachable!(),
+ }
+ if need_to_set {
+ fd.set_cloexec()?;
+ }
+ Ok(())
+ }
+
+ #[cfg(not(target_os = "linux"))]
+ fn ensure_cloexec(_: &FileDesc) -> io::Result<()> {
+ Ok(())
}
+ ensure_cloexec(&fd)?;
Ok(File(fd))
}