func getExitPipe(path string) (*os.File, error) {
if err := unix.Mkfifo(path, 0755); err != nil && !os.IsExist(err) {
return nil, err
}
// add NONBLOCK in case the other side has already closed or else
// this function would never return
return os.OpenFile(path, syscall.O_RDONLY|syscall.O_NONBLOCK, 0)
}
// mktmpfifo creates a temporary FIFO and provides a cleanup function.
func mktmpfifo(t *testing.T) (*os.File, func()) {
err := unix.Mkfifo("fifo", 0666)
if err != nil {
t.Fatalf("mktmpfifo: failed to create FIFO: %v", err)
}
f, err := os.OpenFile("fifo", os.O_RDWR, 0666)
if err != nil {
os.Remove("fifo")
t.Fatalf("mktmpfifo: failed to open FIFO: %v", err)
}
return f, func() {
f.Close()
os.Remove("fifo")
}
}
func getControlPipe(path string) (*os.File, error) {
if err := unix.Mkfifo(path, 0755); err != nil && !os.IsExist(err) {
return nil, err
}
return os.OpenFile(path, syscall.O_RDWR|syscall.O_NONBLOCK, 0)
}
// OpenFifo opens a fifo. Returns io.ReadWriteCloser.
// Context can be used to cancel this function until open(2) has not returned.
// Accepted flags:
// - syscall.O_CREAT - create new fifo if one doesn't exist
// - syscall.O_RDONLY - open fifo only from reader side
// - syscall.O_WRONLY - open fifo only from writer side
// - syscall.O_RDWR - open fifo from both sides, never block on syscall level
// - syscall.O_NONBLOCK - return io.ReadWriteCloser even if other side of the
// fifo isn't open. read/write will be connected after the actual fifo is
// open or after fifo is closed.
func OpenFifo(ctx context.Context, fn string, flag int, perm os.FileMode) (io.ReadWriteCloser, error) {
if _, err := os.Stat(fn); err != nil {
if os.IsNotExist(err) && flag&syscall.O_CREAT != 0 {
if err := unix.Mkfifo(fn, uint32(perm&os.ModePerm)); err != nil && !os.IsExist(err) {
return nil, errors.Wrapf(err, "error creating fifo %v", fn)
}
} else {
return nil, err
}
}
block := flag&syscall.O_NONBLOCK == 0 || flag&syscall.O_RDWR != 0
flag &= ^syscall.O_CREAT
flag &= ^syscall.O_NONBLOCK
h, err := getHandle(fn)
if err != nil {
return nil, err
}
f := &fifo{
handle: h,
flag: flag,
opened: make(chan struct{}),
closed: make(chan struct{}),
closing: make(chan struct{}),
}
wg := leakCheckWg
if wg != nil {
wg.Add(2)
}
go func() {
if wg != nil {
defer wg.Done()
}
select {
case <-ctx.Done():
f.Close()
case <-f.opened:
case <-f.closed:
}
}()
go func() {
if wg != nil {
defer wg.Done()
}
var file *os.File
fn, err := h.Path()
if err == nil {
file, err = os.OpenFile(fn, flag, 0)
}
select {
case <-f.closing:
if err == nil {
select {
case <-ctx.Done():
err = ctx.Err()
default:
err = errors.Errorf("fifo %v was closed before opening", h.Name())
}
if file != nil {
file.Close()
}
}
default:
}
if err != nil {
f.closedOnce.Do(func() {
f.err = err
close(f.closed)
})
return
}
f.file = file
close(f.opened)
}()
if block {
select {
case <-f.opened:
case <-f.closed:
return nil, f.err
}
}
return f, nil
}