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DisableCanonicalMode.go
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DisableCanonicalMode.go
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package utils
import (
"bytes"
"os"
"os/exec"
"strings"
)
type ttyState struct {
state string
logger Logger
}
// DisableCanonicalMode disables canonical mode on the terminal.
// This allows for reading single characters without pressing enter.
// The previous state is returned and can be used to restore the previous state.
// The optionalLogger can be used a preferred logger.
// If no optionalLogger is provided, a default logger is used.
//
// Usage in main.go: defer utils.RestoreTTY(utils.DisableCanonicalMode())
func DisableCanonicalMode(optionalLogger ...Logger) *ttyState {
var l Logger = &defaultLogger{}
if len(optionalLogger) > 0 {
l = optionalLogger[0]
}
fh, err := os.OpenFile("/dev/tty", os.O_RDWR, 0666)
if err != nil {
l.Errorf("Could not open /dev/tty: %v", err)
return nil
}
previousState := getSttyState(fh, l)
// set new state: -icanon (disable canonical mode)
if err := setSttyState(fh, &ttyState{
state: "-icanon",
logger: l,
}); err != nil {
l.Warnf("Could not set stty state: %v", err)
return nil
}
return previousState
}
// RestoreTTY restores the previous state of the terminal.
// The previous state is returned by DisableCanonicalMode.
// If the ttyState is nil, nothing is done.
func RestoreTTY(state *ttyState) {
if state == nil {
return
}
fh, err := os.OpenFile("/dev/tty", os.O_RDWR, 0666)
if err != nil {
state.logger.Errorf("Could not open /dev/tty: %v", err)
}
if err := setSttyState(fh, state); err != nil {
state.logger.Warnf("Could not restore stty state: %v", err)
}
}
func setSttyState(f *os.File, state *ttyState) error {
outputBuf := new(bytes.Buffer)
cmd := exec.Command("stty", state.state)
cmd.Stdin = f
cmd.Stdout = outputBuf
cmd.Stderr = os.Stderr
return cmd.Run()
}
func getSttyState(f *os.File, logger Logger) *ttyState {
outputBuf := new(bytes.Buffer)
cmd := exec.Command("stty", "-g")
cmd.Stdin = f
cmd.Stdout = outputBuf
if err := cmd.Run(); err != nil {
return &ttyState{
state: "",
logger: logger,
}
}
return &ttyState{
state: strings.TrimSuffix(outputBuf.String(), "\n"),
logger: logger,
}
}