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.

1 files changed, 98 insertions, 0 deletions

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
+}