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std: When duplicating fds, skip extra set_cloexec

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Similar to the previous commit, if `F_DUPFD_CLOEXEC` succeeds then there's no
need for us to then call `set_cloexec` on platforms other than Linux. The bug
mentioned of kernels not actually setting the `CLOEXEC` flag has only been
repored on Linux, not elsewhere.
This commit is contained in:
Alex Crichton 2016-02-04 13:22:51 -08:00
parent 64d7eca0e5
commit 0fff73b64a
1 changed files with 15 additions and 6 deletions
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21
src/libstd/sys/unix/fd.rs
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@ -77,9 +77,7 @@ impl FileDesc {
// follow a strategy similar to musl [1] where if passing
// F_DUPFD_CLOEXEC causes `fcntl` to return EINVAL it means it's not
// supported (the third parameter, 0, is always valid), so we stop
// trying that. We also *still* call the `set_cloexec` method as
// apparently some kernel at some point stopped setting CLOEXEC even
// though it reported doing so on F_DUPFD_CLOEXEC.
// trying that.
//
// Also note that Android doesn't have F_DUPFD_CLOEXEC, but get it to
// resolve so we at least compile this.
@ -95,14 +93,25 @@ impl FileDesc {
fd.set_cloexec();
fd
};
static TRY_CLOEXEC: AtomicBool = AtomicBool::new(true);
static TRY_CLOEXEC: AtomicBool =
AtomicBool::new(!cfg!(target_os = "android"));
let fd = self.raw();
if !cfg!(target_os = "android") && TRY_CLOEXEC.load(Ordering::Relaxed) {
if TRY_CLOEXEC.load(Ordering::Relaxed) {
match cvt(unsafe { libc::fcntl(fd, F_DUPFD_CLOEXEC, 0) }) {
// We *still* call the `set_cloexec` method as apparently some
// linux kernel at some point stopped setting CLOEXEC even
// though it reported doing so on F_DUPFD_CLOEXEC.
Ok(fd) => {
return Ok(if cfg!(target_os = "linux") {
make_filedesc(fd)
} else {
FileDesc::new(fd)
})
}
Err(ref e) if e.raw_os_error() == Some(libc::EINVAL) => {
TRY_CLOEXEC.store(false, Ordering::Relaxed);
}
res => return res.map(make_filedesc),
Err(e) => return Err(e),
}
}
cvt(unsafe { libc::fcntl(fd, libc::F_DUPFD, 0) }).map(make_filedesc)