Added password prompt with asterisks displayed while typing

AGENTS.md

@@ -17,6 +17,7 @@
   - `1` runtime/SFTP error
   - `2` argument/usage error
 - Missing `--host`, `--user`, `--password` should still support interactive prompt mode.
+- Interactive password prompts should avoid echoing the password, mask typed characters when possible, and restore terminal settings after input errors.
 - `--skip` and `--skip-delete` matching semantics should remain stable.
   - Rules without wildcard characters (`*`, `?`) use legacy exact matching.
   - Exact rules without slash match any path segment; exact rules with slash match a relative subpath.

README.md

@@ -25,7 +25,7 @@ From repository root:
 php src/SFTPsync.php --host example.com --user myuser --password mypass --sync ./local /var/www/app
 ```
 
-If `--host`, `--user`, or `--password` is missing, the script asks for it interactively (TTY only).
+If `--host`, `--user`, or `--password` is missing, the script asks for it interactively (TTY only). Interactive password input is hidden or masked when the terminal supports it.
 
 ## CLI Usage
 

src/SFTPsync.php

@@ -1213,7 +1213,7 @@ function askForMissingRequiredOptions(array $config): array
 		$config['user'] = promptValue('user');
 	}
 	if ($config['password'] === '') {
-		$config['password'] = promptValue('password');
+		$config['password'] = readPassword('Password: ');
 	}
 
 	return $config;
@@ -1241,6 +1241,215 @@ function promptValue(string $name): string
 	}
 }
 
+function readPassword(string $prompt = 'Password: '): string
+{
+	if (!isInteractiveStdin()) {
+		throw new CliUsageException('Missing required option --password and no interactive input available.');
+	}
+
+	while (true) {
+		$password = trim(readPasswordOnce($prompt));
+		if ($password !== '') {
+			return $password;
+		}
+
+		logError('Value for --password cannot be empty.');
+	}
+}
+
+function readPasswordOnce(string $prompt): string
+{
+	$password = readPasswordFromRawTerminal($prompt);
+	if ($password !== null) {
+		return $password;
+	}
+
+	$password = readPasswordFromWindowsConsole($prompt);
+	if ($password !== null) {
+		return $password;
+	}
+
+	$password = readPasswordWithEchoDisabled($prompt);
+	if ($password !== null) {
+		return $password;
+	}
+
+	// Last-resort fallback for platforms where PHP cannot safely switch the terminal
+	// to no-echo or character-by-character input. This may echo the password.
+	fwrite(STDOUT, $prompt);
+	$line = fgets(STDIN);
+	if ($line === false) {
+		throw new CliUsageException('Could not read --password from interactive input.');
+	}
+
+	return $line;
+}
+
+function readPasswordFromRawTerminal(string $prompt): ?string
+{
+	if (PHP_OS_FAMILY === 'Windows' || !function_exists('shell_exec')) {
+		return null;
+	}
+
+	$originalStty = @shell_exec('stty -g 2>/dev/null');
+	if ($originalStty === null || trim($originalStty) === '') {
+		return null;
+	}
+	$originalStty = trim($originalStty);
+
+	fwrite(STDOUT, $prompt);
+	@shell_exec('stty -icanon -echo min 1 time 0 2>/dev/null');
+
+	$password = '';
+	try {
+		while (true) {
+			$char = fgetc(STDIN);
+			if ($char === false) {
+				throw new CliUsageException('Could not read --password from interactive input.');
+			}
+
+			if ($char === "\n" || $char === "\r") {
+				fwrite(STDOUT, PHP_EOL);
+				return $password;
+			}
+
+			if ($char === "\x03") {
+				throw new CliUsageException('Password input interrupted.');
+			}
+
+			if ($char === "\x04") {
+				throw new CliUsageException('Could not read --password from interactive input.');
+			}
+
+			if ($char === "\x08" || $char === "\x7f") {
+				if ($password !== '') {
+					$password = substr($password, 0, -1);
+					fwrite(STDOUT, "\x08 \x08");
+				}
+				continue;
+			}
+
+			if ($char === "\x1b") {
+				readPasswordHandleEscapeSequence($password);
+				continue;
+			}
+
+			if (ord($char) < 32) {
+				continue;
+			}
+
+			$password .= $char;
+			fwrite(STDOUT, '*');
+		}
+	} finally {
+		@shell_exec('stty ' . escapeshellarg($originalStty) . ' 2>/dev/null');
+	}
+}
+
+function readPasswordHandleEscapeSequence(string &$password): void
+{
+	$second = fgetc(STDIN);
+	$third = fgetc(STDIN);
+	if ($second !== '[' || $third !== '3') {
+		return;
+	}
+
+	$fourth = fgetc(STDIN);
+	if ($fourth === '~' && $password !== '') {
+		$password = substr($password, 0, -1);
+		fwrite(STDOUT, "\x08 \x08");
+	}
+}
+
+function readPasswordFromWindowsConsole(string $prompt): ?string
+{
+	if (PHP_OS_FAMILY !== 'Windows' || !function_exists('proc_open')) {
+		return null;
+	}
+
+	$promptLiteral = "'" . str_replace("'", "''", $prompt) . "'";
+	$script = '$PromptText = ' . $promptLiteral . PHP_EOL . <<<'POWERSHELL'
+[Console]::Error.Write($PromptText)
+$password = New-Object System.Text.StringBuilder
+
+while ($true) {
+	$key = [Console]::ReadKey($true)
+	if ($key.Key -eq [ConsoleKey]::Enter) {
+		[Console]::Error.WriteLine()
+		break
+	}
+	if ($key.Key -eq [ConsoleKey]::Backspace -or $key.Key -eq [ConsoleKey]::Delete) {
+		if ($password.Length -gt 0) {
+			[void]$password.Remove($password.Length - 1, 1)
+			[Console]::Error.Write("`b `b")
+		}
+		continue
+	}
+	if ($key.KeyChar -ne [char]0) {
+		[void]$password.Append($key.KeyChar)
+		[Console]::Error.Write("*")
+	}
+}
+
+[Console]::Out.Write($password.ToString())
+POWERSHELL;
+
+	$process = @proc_open(
+		['powershell.exe', '-NoProfile', '-ExecutionPolicy', 'Bypass', '-Command', $script],
+		[
+			0 => STDIN,
+			1 => ['pipe', 'w'],
+			2 => STDERR,
+		],
+		$pipes
+	);
+	if (!is_resource($process)) {
+		return null;
+	}
+
+	try {
+		$password = stream_get_contents($pipes[1]);
+		fclose($pipes[1]);
+		$exitCode = proc_close($process);
+	} catch (Throwable) {
+		proc_terminate($process);
+		return null;
+	}
+
+	if ($exitCode !== 0 || $password === false) {
+		return null;
+	}
+
+	return $password;
+}
+
+function readPasswordWithEchoDisabled(string $prompt): ?string
+{
+	if (PHP_OS_FAMILY === 'Windows' || !function_exists('shell_exec')) {
+		return null;
+	}
+
+	$originalStty = @shell_exec('stty -g 2>/dev/null');
+	if ($originalStty === null || trim($originalStty) === '') {
+		return null;
+	}
+	$originalStty = trim($originalStty);
+
+	fwrite(STDOUT, $prompt);
+	@shell_exec('stty -echo 2>/dev/null');
+	try {
+		$line = fgets(STDIN);
+		if ($line === false) {
+			throw new CliUsageException('Could not read --password from interactive input.');
+		}
+		fwrite(STDOUT, PHP_EOL);
+
+		return $line;
+	} finally {
+		@shell_exec('stty ' . escapeshellarg($originalStty) . ' 2>/dev/null');
+	}
+}
+
 function isInteractiveStdin(): bool
 {
 	if (!defined('STDIN')) {