forked from Mirrors/bubbletea
138 lines
3.0 KiB
Go
138 lines
3.0 KiB
Go
//go:build solaris || darwin || freebsd || netbsd || openbsd
|
|
// +build solaris darwin freebsd netbsd openbsd
|
|
|
|
// nolint:revive
|
|
package tea
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
"io"
|
|
"os"
|
|
"strings"
|
|
|
|
"golang.org/x/sys/unix"
|
|
)
|
|
|
|
// newSelectCancelReader returns a reader and a cancel function. If the input
|
|
// reader is an *os.File, the cancel function can be used to interrupt a
|
|
// blocking call read call. In this case, the cancel function returns true if
|
|
// the call was cancelled successfully. If the input reader is not a *os.File or
|
|
// the file descriptor is 1024 or larger, the cancel function does nothing and
|
|
// always returns false. The generic unix implementation is based on the posix
|
|
// select syscall.
|
|
func newSelectCancelReader(reader io.Reader) (cancelReader, error) {
|
|
file, ok := reader.(*os.File)
|
|
if !ok || file.Fd() >= unix.FD_SETSIZE {
|
|
return newFallbackCancelReader(reader)
|
|
}
|
|
r := &selectCancelReader{file: file}
|
|
|
|
var err error
|
|
|
|
r.cancelSignalReader, r.cancelSignalWriter, err = os.Pipe()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
return r, nil
|
|
}
|
|
|
|
type selectCancelReader struct {
|
|
file *os.File
|
|
cancelSignalReader *os.File
|
|
cancelSignalWriter *os.File
|
|
cancelMixin
|
|
}
|
|
|
|
func (r *selectCancelReader) Read(data []byte) (int, error) {
|
|
if r.isCancelled() {
|
|
return 0, errCanceled
|
|
}
|
|
|
|
for {
|
|
err := waitForRead(r.file, r.cancelSignalReader)
|
|
if err != nil {
|
|
if errors.Is(err, unix.EINTR) {
|
|
continue // try again if the syscall was interrupted
|
|
}
|
|
|
|
if errors.Is(err, errCanceled) {
|
|
// remove signal from pipe
|
|
var b [1]byte
|
|
_, readErr := r.cancelSignalReader.Read(b[:])
|
|
if readErr != nil {
|
|
return 0, fmt.Errorf("reading cancel signal: %w", readErr)
|
|
}
|
|
}
|
|
|
|
return 0, err
|
|
}
|
|
|
|
return r.file.Read(data)
|
|
}
|
|
}
|
|
|
|
func (r *selectCancelReader) Cancel() bool {
|
|
r.setCancelled()
|
|
|
|
// send cancel signal
|
|
_, err := r.cancelSignalWriter.Write([]byte{'c'})
|
|
return err == nil
|
|
}
|
|
|
|
func (r *selectCancelReader) Close() error {
|
|
var errMsgs []string
|
|
|
|
// close pipe
|
|
err := r.cancelSignalWriter.Close()
|
|
if err != nil {
|
|
errMsgs = append(errMsgs, fmt.Sprintf("closing cancel signal writer: %v", err))
|
|
}
|
|
|
|
err = r.cancelSignalReader.Close()
|
|
if err != nil {
|
|
errMsgs = append(errMsgs, fmt.Sprintf("closing cancel signal reader: %v", err))
|
|
}
|
|
|
|
if len(errMsgs) > 0 {
|
|
return fmt.Errorf(strings.Join(errMsgs, ", "))
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
func waitForRead(reader *os.File, abort *os.File) error {
|
|
readerFd := int(reader.Fd())
|
|
abortFd := int(abort.Fd())
|
|
|
|
maxFd := readerFd
|
|
if abortFd > maxFd {
|
|
maxFd = abortFd
|
|
}
|
|
|
|
// this is a limitation of the select syscall
|
|
if maxFd >= unix.FD_SETSIZE {
|
|
return fmt.Errorf("cannot select on file descriptor %d which is larger than 1024", maxFd)
|
|
}
|
|
|
|
fdSet := &unix.FdSet{}
|
|
fdSet.Set(int(reader.Fd()))
|
|
fdSet.Set(int(abort.Fd()))
|
|
|
|
_, err := unix.Select(maxFd+1, fdSet, nil, nil, nil)
|
|
if err != nil {
|
|
return fmt.Errorf("select: %w", err)
|
|
}
|
|
|
|
if fdSet.IsSet(abortFd) {
|
|
return errCanceled
|
|
}
|
|
|
|
if fdSet.IsSet(readerFd) {
|
|
return nil
|
|
}
|
|
|
|
return fmt.Errorf("select returned without setting a file descriptor")
|
|
}
|