rwcancel: use poll instead of select

Suggested-by: Lennart Poettering <lennart@poettering.net>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

diff --git a/rwcancel/fdset.go b/rwcancel/fdset.go
deleted file mode 100644 (file)
index 2c5ca9e..0000000
--- a/rwcancel/fdset.go
+++ /dev/null
@@ -1,24 +0,0 @@
-// +build !windows
-
-/* SPDX-License-Identifier: MIT
- *
- * Copyright (C) 2017-2021 WireGuard LLC. All Rights Reserved.
- */
-
-package rwcancel
-
-import "golang.org/x/sys/unix"
-
-type fdSet struct {
-       unix.FdSet
-}
-
-func (fdset *fdSet) set(i int) {
-       bits := 32 << (^uint(0) >> 63)
-       fdset.Bits[i/bits] |= 1 << uint(i%bits)
-}
-
-func (fdset *fdSet) check(i int) bool {
-       bits := 32 << (^uint(0) >> 63)
-       return (fdset.Bits[i/bits] & (1 << uint(i%bits))) != 0
-}

diff --git a/rwcancel/rwcancel.go b/rwcancel/rwcancel.go
index 70eb4ca0ec5de9c7778b5597af4204190e9e0e04..05484e10ac1b9c262d26fe01906290cd41925153 100644 (file)
--- a/rwcancel/rwcancel.go
+++ b/rwcancel/rwcancel.go
@@ -17,13 +17,6 @@ import (
        "golang.org/x/sys/unix"
 )
 
-func max(a, b int) int {
-       if a > b {
-               return a
-       }
-       return b
-}
-
 type RWCancel struct {
        fd            int
        closingReader *os.File
@@ -50,13 +43,12 @@ func RetryAfterError(err error) bool {
 }
 
 func (rw *RWCancel) ReadyRead() bool {
-       closeFd := int(rw.closingReader.Fd())
-       fdset := fdSet{}
-       fdset.set(rw.fd)
-       fdset.set(closeFd)
+       closeFd := int32(rw.closingReader.Fd())
+
+       pollFds := []unix.PollFd{{Fd: int32(rw.fd), Events: unix.POLLIN}, {Fd: closeFd, Events: unix.POLLIN}}
        var err error
        for {
-               err = unixSelect(max(rw.fd, closeFd)+1, &fdset.FdSet, nil, nil, nil)
+               _, err = unix.Poll(pollFds, -1)
                if err == nil || !RetryAfterError(err) {
                        break
                }
@@ -64,20 +56,18 @@ func (rw *RWCancel) ReadyRead() bool {
        if err != nil {
                return false
        }
-       if fdset.check(closeFd) {
+       if pollFds[1].Revents != 0 {
                return false
        }
-       return fdset.check(rw.fd)
+       return pollFds[0].Revents != 0
 }
 
 func (rw *RWCancel) ReadyWrite() bool {
-       closeFd := int(rw.closingReader.Fd())
-       fdset := fdSet{}
-       fdset.set(rw.fd)
-       fdset.set(closeFd)
+       closeFd := int32(rw.closingReader.Fd())
+       pollFds := []unix.PollFd{{Fd: int32(rw.fd), Events: unix.POLLOUT}, {Fd: closeFd, Events: unix.POLLOUT}}
        var err error
        for {
-               err = unixSelect(max(rw.fd, closeFd)+1, nil, &fdset.FdSet, nil, nil)
+               _, err = unix.Poll(pollFds, -1)
                if err == nil || !RetryAfterError(err) {
                        break
                }
@@ -85,10 +75,11 @@ func (rw *RWCancel) ReadyWrite() bool {
        if err != nil {
                return false
        }
-       if fdset.check(closeFd) {
+
+       if pollFds[1].Revents != 0 {
                return false
        }
-       return fdset.check(rw.fd)
+       return pollFds[0].Revents != 0
 }
 
 func (rw *RWCancel) Read(p []byte) (n int, err error) {

diff --git a/rwcancel/select_default.go b/rwcancel/select_default.go
deleted file mode 100644 (file)
index 990de83..0000000
--- a/rwcancel/select_default.go
+++ /dev/null
@@ -1,15 +0,0 @@
-// +build !linux,!windows
-
-/* SPDX-License-Identifier: MIT
- *
- * Copyright (C) 2017-2021 WireGuard LLC. All Rights Reserved.
- */
-
-package rwcancel
-
-import "golang.org/x/sys/unix"
-
-func unixSelect(nfd int, r *unix.FdSet, w *unix.FdSet, e *unix.FdSet, timeout *unix.Timeval) error {
-       _, err := unix.Select(nfd, r, w, e, timeout)
-       return err
-}

diff --git a/rwcancel/select_linux.go b/rwcancel/select_linux.go
deleted file mode 100644 (file)
index ac941fd..0000000
--- a/rwcancel/select_linux.go
+++ /dev/null
@@ -1,13 +0,0 @@
-/* SPDX-License-Identifier: MIT
- *
- * Copyright (C) 2017-2021 WireGuard LLC. All Rights Reserved.
- */
-
-package rwcancel
-
-import "golang.org/x/sys/unix"
-
-func unixSelect(nfd int, r *unix.FdSet, w *unix.FdSet, e *unix.FdSet, timeout *unix.Timeval) (err error) {
-       _, err = unix.Select(nfd, r, w, e, timeout)
-       return
-}