rwcancel: use poll instead of select

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

1 files changed, 12 insertions, 21 deletions

diff --git a/rwcancel/rwcancel.go b/rwcancel/rwcancel.go
index 70eb4ca..05484e1 100644
--- 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) {