path: root/cmd/utils/input.go

// Copyright 2016 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// go-ethereum is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.

package utils

import (
    "fmt"
    "strings"

    "github.com/peterh/liner"
)

// Holds the stdin line reader.
// Only this reader may be used for input because it keeps
// an internal buffer.
var Stdin = newUserInputReader()

type userInputReader struct {
    *liner.State
    warned     bool
    supported  bool
    normalMode liner.ModeApplier
    rawMode    liner.ModeApplier
}

func newUserInputReader() *userInputReader {
    r := new(userInputReader)
    // Get the original mode before calling NewLiner.
    // This is usually regular "cooked" mode where characters echo.
    normalMode, _ := liner.TerminalMode()
    // Turn on liner. It switches to raw mode.
    r.State = liner.NewLiner()
    rawMode, err := liner.TerminalMode()
    if err != nil || !liner.TerminalSupported() {
        r.supported = false
    } else {
        r.supported = true
        r.normalMode = normalMode
        r.rawMode = rawMode
        // Switch back to normal mode while we're not prompting.
        normalMode.ApplyMode()
    }
    return r
}

func (r *userInputReader) Prompt(prompt string) (string, error) {
    if r.supported {
        r.rawMode.ApplyMode()
        defer r.normalMode.ApplyMode()
    } else {
        // liner tries to be smart about printing the prompt
        // and doesn't print anything if input is redirected.
        // Un-smart it by printing the prompt always.
        fmt.Print(prompt)
        prompt = ""
        defer fmt.Println()
    }
    return r.State.Prompt(prompt)
}

func (r *userInputReader) PasswordPrompt(prompt string) (passwd string, err error) {
    if r.supported {
        r.rawMode.ApplyMode()
        defer r.normalMode.ApplyMode()
        return r.State.PasswordPrompt(prompt)
    }
    if !r.warned {
        fmt.Println("!! Unsupported terminal, password will be echoed.")
        r.warned = true
    }
    // Just as in Prompt, handle printing the prompt here instead of relying on liner.
    fmt.Print(prompt)
    passwd, err = r.State.Prompt("")
    fmt.Println()
    return passwd, err
}

func (r *userInputReader) ConfirmPrompt(prompt string) (bool, error) {
    prompt = prompt + " [y/N] "
    input, err := r.Prompt(prompt)
    if len(input) > 0 && strings.ToUpper(input[:1]) == "Y" {
        return true, nil
    }
    return false, err
}