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fixes #67 DialPipe problem with multiple calls / waiting for busy pipe #80

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merged 2 commits into from
Jul 19, 2018
Merged

fixes #67 DialPipe problem with multiple calls / waiting for busy pipe #80

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ecd994b
fixes #67 DialPipe problem with multiple calls / waiting for busy pipe
gdamore Jun 24, 2018
effecfb
Reduce the timeout to 2 seconds, and close the client handle.
gdamore Jul 18, 2018
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43 changes: 22 additions & 21 deletions pipe.go
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,6 @@ import (
//sys connectNamedPipe(pipe syscall.Handle, o *syscall.Overlapped) (err error) = ConnectNamedPipe
//sys createNamedPipe(name string, flags uint32, pipeMode uint32, maxInstances uint32, outSize uint32, inSize uint32, defaultTimeout uint32, sa *syscall.SecurityAttributes) (handle syscall.Handle, err error) [failretval==syscall.InvalidHandle] = CreateNamedPipeW
//sys createFile(name string, access uint32, mode uint32, sa *syscall.SecurityAttributes, createmode uint32, attrs uint32, templatefile syscall.Handle) (handle syscall.Handle, err error) [failretval==syscall.InvalidHandle] = CreateFileW
//sys waitNamedPipe(name string, timeout uint32) (err error) = WaitNamedPipeW
//sys getNamedPipeInfo(pipe syscall.Handle, flags *uint32, outSize *uint32, inSize *uint32, maxInstances *uint32) (err error) = GetNamedPipeInfo
//sys getNamedPipeHandleState(pipe syscall.Handle, state *uint32, curInstances *uint32, maxCollectionCount *uint32, collectDataTimeout *uint32, userName *uint16, maxUserNameSize uint32) (err error) = GetNamedPipeHandleStateW
//sys localAlloc(uFlags uint32, length uint32) (ptr uintptr) = LocalAlloc
Expand Down Expand Up @@ -134,12 +133,14 @@ func (s pipeAddress) String() string {
}

// DialPipe connects to a named pipe by path, timing out if the connection
// takes longer than the specified duration. If timeout is nil, then the timeout
// is the default timeout established by the pipe server.
// takes longer than the specified duration. If timeout is nil, then we use
// a default timeout of 5 seconds. (We do not use WaitNamedPipe.)
func DialPipe(path string, timeout *time.Duration) (net.Conn, error) {
var absTimeout time.Time
if timeout != nil {
absTimeout = time.Now().Add(*timeout)
} else {
absTimeout = time.Now().Add(time.Second * 5)
}
var err error
var h syscall.Handle
Expand All @@ -148,22 +149,13 @@ func DialPipe(path string, timeout *time.Duration) (net.Conn, error) {
if err != cERROR_PIPE_BUSY {
break
}
now := time.Now()
var ms uint32
if absTimeout.IsZero() {
ms = cNMPWAIT_USE_DEFAULT_WAIT
} else if now.After(absTimeout) {
ms = cNMPWAIT_NOWAIT
} else {
ms = uint32(absTimeout.Sub(now).Nanoseconds() / 1000 / 1000)
}
err = waitNamedPipe(path, ms)
if err != nil {
if err == cERROR_SEM_TIMEOUT {
return nil, ErrTimeout
}
break
if time.Now().After(absTimeout) {
return nil, ErrTimeout
}

// Wait 10 msec and try again. This is a rather simplistic
// view, as we always try each 10 milliseconds.
time.Sleep(time.Millisecond * 10)
}
if err != nil {
return nil, &os.PathError{Op: "open", Path: path, Err: err}
Expand Down Expand Up @@ -208,6 +200,7 @@ type acceptResponse struct {

type win32PipeListener struct {
firstHandle syscall.Handle
clientHandle syscall.Handle
path string
securityDescriptor []byte
config PipeConfig
Expand Down Expand Up @@ -310,6 +303,8 @@ func (l *win32PipeListener) listenerRoutine() {
}
syscall.Close(l.firstHandle)
l.firstHandle = 0
syscall.Close(l.clientHandle)
l.clientHandle = 0
// Notify Close() and Accept() callers that the handle has been closed.
close(l.doneCh)
}
Expand Down Expand Up @@ -354,16 +349,22 @@ func ListenPipe(path string, c *PipeConfig) (net.Listener, error) {
if err != nil {
return nil, err
}
// Immediately open and then close a client handle so that the named pipe is
// created but not currently accepting connections.
// Create a client handle and connect it. This results in the pipe
// instance always existing, so that clients see ERROR_PIPE_BUSY
// rather than ERROR_FILE_NOT_FOUND. This ties the first instance
// up so that no other instances can be used. This would have been
// cleaner if the Win32 API matched CreateFile with ConnectNamedPipe
// instead of CreateNamedPipe. (Apparently created named pipes are
// considered to be in listening state regardless of whether any
// active calls to ConnectNamedPipe are outstanding.)
h2, err := createFile(path, 0, 0, nil, syscall.OPEN_EXISTING, cSECURITY_SQOS_PRESENT|cSECURITY_ANONYMOUS, 0)
if err != nil {
syscall.Close(h)
return nil, err
}
syscall.Close(h2)
l := &win32PipeListener{
firstHandle: h,
clientHandle: h2,
path: path,
securityDescriptor: sd,
config: *c,
Expand Down