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Cleanup epoll_create fallback

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Now allows the fallback on all platforms, if we doing one why not all?

Also properly closes the file descriptor if the fcntl call fails.
This commit is contained in:
Thomas de Zeeuw
2022-07-17 22:00:48 +02:00
parent 6800c2f7fb
commit c4e4e0cef8
1 changed files with 34 additions and 38 deletions
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src/sys/unix/selector/epoll.rs
+34 -38
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@@ -23,7 +23,40 @@ pub struct Selector {
impl Selector {
pub fn new() -> io::Result<Selector> {
let ep = new_epoll_fd()?;
#[cfg(not(target_os = "android"))]
let res = syscall!(epoll_create1(libc::O_CLOEXEC));
// On Android < API level 16 `epoll_create1` is not defined, so use a
// raw system call.
// According to libuv, `EPOLL_CLOEXEC` is not defined on Android API <
// 21. But `EPOLL_CLOEXEC` is an alias for `O_CLOEXEC` on that platform,
// so we use it instead.
#[cfg(target_os = "android")]
let res = syscall!(syscall(libc::SYS_epoll_create1, libc::EPOLL_CLOEXEC));
let ep = match res {
Ok(ep) => ep as RawFd,
Err(err) => {
// When `epoll_create1` is not available fall back to use
// `epoll_create` followed by `fcntl`.
if let Some(libc::ENOSYS) = err.raw_os_error() {
match syscall!(epoll_create(1024)) {
Ok(ep) => match syscall!(fcntl(ep, libc::F_SETFD, libc::FD_CLOEXEC)) {
Ok(ep) => ep as RawFd,
Err(err) => {
// `fcntl` failed, cleanup `ep`.
let _ = unsafe { libc::close(ep) };
return Err(err);
}
},
Err(err) => return Err(err),
}
} else {
return Err(err);
}
}
};
Ok(Selector {
#[cfg(debug_assertions)]
id: NEXT_ID.fetch_add(1, Ordering::Relaxed),
@@ -126,43 +159,6 @@ impl Drop for Selector {
}
}
/// Creates a new epoll file descriptor with close-on-exec flag set.
///
/// close-on-exec is set atomically with `epoll_create1()` if possible,
/// otherwise `epoll_create()` and `fcntl()` calls are used as a fallback.
fn new_epoll_fd() -> io::Result<libc::c_int> {
// According to libuv, `EPOLL_CLOEXEC` is not defined on Android API <
// 21. But `EPOLL_CLOEXEC` is an alias for `O_CLOEXEC` on that platform,
// so we use it instead.
#[cfg(target_os = "android")]
let flag = libc::O_CLOEXEC;
#[cfg(not(target_os = "android"))]
let flag = libc::EPOLL_CLOEXEC;
#[cfg(not(target_os = "android"))]
let ep = syscall!(epoll_create1(flag))?;
// On Android try to use epoll_create1 syscall with an epoll_create fallback
// to support Android API level 16 which does not define epoll_create1 function.
#[cfg(target_os = "android")]
let ep = syscall!(syscall(libc::SYS_epoll_create1, flag))
.map(|fd| fd as libc::c_int)
.or_else(|e| {
match e.raw_os_error() {
Some(libc::ENOSYS) => {
// Using epoll_create() followed by fcntl() instead of epoll_create1() with EPOLL_CLOEXEC
// flag for backwards compatibility.
let ep = syscall!(epoll_create(1024))?;
syscall!(fcntl(ep, libc::F_SETFD, libc::FD_CLOEXEC)).map(|_| ep)
}
_ => Err(e),
}
})?;
Ok(ep)
}
fn interests_to_epoll(interests: Interest) -> u32 {
let mut kind = EPOLLET;