Read 'hidden' input for CLI Dart app - input

Question

What's the best way to receive 'hidden' input from a command-line Dart application? For example, in Bash, this is accomplished with:
read -s SOME_VAR

Answer 1

Set io.stdin.echoMode to false:
import 'dart:io' as io;
void main() {
io.stdin.echoMode = false;
String input = io.stdin.readLineSync();
// or
var input;
while(input != 32) {
input = io.stdin.readByteSync();
if(input != 10) print(input);
}
// restore echoMode
io.stdin.echoMode = true;
}

Answer 2

This is a slightly extended version, key differences are that it uses a finally block to ensure the mode is reset if an exception is thrown whilst the code is executing.
The code also uses a waitFor call (only available in dart cli apps) to turn this code into a synchronous call. Given this is a cli command there is no need for the complications that futures bring to the table.
The code also does the classic output of '*' as you type.
If you are doing much cli work the below code is from the dart package I'm working on called dcli. Have a look at the 'ask' method.
https://pub.dev/packages/dcli
String readHidden() {
var line = <int>[];
try {
stdin.echoMode = false;
stdin.lineMode = false;
int char;
do {
char = stdin.readByteSync();
if (char != 10) {
stdout.write('*');
// we must wait for flush as only one flush can be outstanding at a time.
waitFor<void>(stdout.flush());
line.add(char);
}
} while (char != 10);
} finally {
stdin.echoMode = true;
stdin.lineMode = true;
}
// output a newline as we have suppressed it.
print('');
return Encoding.getByName('utf-8').decode(line);
}