cmd/geth, cmd/utils: improve input handling

These changes make prompting behave consistently on all platforms:

* The input buffer is now global.
  Buffering was previously set up for each prompt, which can cause weird
  behaviour, e.g. when running "geth account update <input.txt" where
  input.txt contains three lines. In this case, the first password
  prompt would fill up the buffer with all lines and then use only the
  first one.

* Print the "unsupported terminal" warning only once.
  Now that stdin prompting has global state, we can use it to track
  the warning there.

* Work around small liner issues, particularly on Windows.
  Prompting didn't work under most of the third-party terminal emulators
  on Windows because liner assumes line editing is always available.

3 files changed, 103 insertions, 54 deletions

diff --git a/cmd/utils/cmd.go b/cmd/utils/cmd.go
index eb7907b0c..d331f762f 100644
--- a/cmd/utils/cmd.go
+++ b/cmd/utils/cmd.go
@@ -18,13 +18,11 @@
 package utils
 
 import (
-	"bufio"
 	"fmt"
 	"io"
 	"os"
 	"os/signal"
 	"regexp"
-	"strings"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core"
@@ -34,17 +32,12 @@ import (
 	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/node"
 	"github.com/ethereum/go-ethereum/rlp"
-	"github.com/peterh/liner"
 )
 
 const (
 	importBatchSize = 2500
 )
 
-var (
-	interruptCallbacks = []func(os.Signal){}
-)
-
 func openLogFile(Datadir string, filename string) *os.File {
 	path := common.AbsolutePath(Datadir, filename)
 	file, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0666)
@@ -54,49 +47,6 @@ func openLogFile(Datadir string, filename string) *os.File {
 	return file
 }
 
-func PromptConfirm(prompt string) (bool, error) {
-	var (
-		input string
-		err   error
-	)
-	prompt = prompt + " [y/N] "
-
-	// if liner.TerminalSupported() {
-	// 	fmt.Println("term")
-	// 	lr := liner.NewLiner()
-	// 	defer lr.Close()
-	// 	input, err = lr.Prompt(prompt)
-	// } else {
-	fmt.Print(prompt)
-	input, err = bufio.NewReader(os.Stdin).ReadString('\n')
-	fmt.Println()
-	// }
-
-	if len(input) > 0 && strings.ToUpper(input[:1]) == "Y" {
-		return true, nil
-	} else {
-		return false, nil
-	}
-
-	return false, err
-}
-
-func PromptPassword(prompt string, warnTerm bool) (string, error) {
-	if liner.TerminalSupported() {
-		lr := liner.NewLiner()
-		defer lr.Close()
-		return lr.PasswordPrompt(prompt)
-	}
-	if warnTerm {
-		fmt.Println("!! Unsupported terminal, password will be echoed.")
-	}
-	fmt.Print(prompt)
-	input, err := bufio.NewReader(os.Stdin).ReadString('\n')
-	input = strings.TrimRight(input, "\r\n")
-	fmt.Println()
-	return input, err
-}
-
 // Fatalf formats a message to standard error and exits the program.
 // The message is also printed to standard output if standard error
 // is redirected to a different file.
diff --git a/cmd/utils/input.go b/cmd/utils/input.go
new file mode 100644
index 000000000..523d5a587
--- /dev/null
+++ b/cmd/utils/input.go
@@ -0,0 +1,98 @@
+// 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
+}
diff --git a/cmd/utils/jeth.go b/cmd/utils/jeth.go
index 35fcd4bed..708d457c6 100644
--- a/cmd/utils/jeth.go
+++ b/cmd/utils/jeth.go
@@ -75,8 +75,9 @@ func (self *Jeth) UnlockAccount(call otto.FunctionCall) (response otto.Value) {
 	// if password is not given or as null value -> ask user for password
 	if call.Argument(1).IsUndefined() || call.Argument(1).IsNull() {
 		fmt.Printf("Unlock account %s\n", account)
-		if password, err := PromptPassword("Passphrase: ", true); err == nil {
-			passwd, _ = otto.ToValue(password)
+		if input, err := Stdin.PasswordPrompt("Passphrase: "); err != nil {
+			return otto.FalseValue()
+			passwd, _ = otto.ToValue(input)
 		} else {
 			throwJSExeception(err.Error())
 		}
@@ -111,11 +112,11 @@ func (self *Jeth) NewAccount(call otto.FunctionCall) (response otto.Value) {
 	var passwd string
 	if len(call.ArgumentList) == 0 {
 		var err error
-		passwd, err = PromptPassword("Passphrase: ", true)
+		passwd, err = Stdin.PasswordPrompt("Passphrase: ")
 		if err != nil {
 			return otto.FalseValue()
 		}
-		passwd2, err := PromptPassword("Repeat passphrase: ", true)
+		passwd2, err := Stdin.PasswordPrompt("Repeat passphrase: ")
 		if err != nil {
 			return otto.FalseValue()
 		}