bare-operating-system/packages/bare-os-coreutils/lib/interactive-masked-line.js

/**
 * Plain-stream masked line input (same pattern as agent --config / bareAgentPromptSetupLine).
 * Used by /bin/login so the Fish REPL is suspended and stdin/stdout are the TTY streams.
 */

/**
 * @param {Record<string, unknown> | undefined} ctx
 * @param {import('stream').Writable | undefined} out
 * @param {string} s
 */
function bareLoginInteractiveWrite(ctx, out, s) {
  const text =
    ctx && ctx.bareOsPtyStdoutCrlf
      ? String(s).replace(/\r?\n/g, '\r\n')
      : String(s)
  if (out && typeof out.write === 'function') {
    try {
      out.write(text)
    } catch {
      /* ignore */
    }
  }
}

/**
 * @param {import('stream').Readable} stdin
 * @returns {Promise<string>}
 */
function bareLoginReadStreamLineOnce(stdin) {
  return new Promise((resolve) => {
    let acc = ''
    /** @param {string | Uint8Array | Buffer} chunk */
    function onData(chunk) {
      let s = ''
      if (typeof chunk === 'string') s = chunk
      else if (chunk instanceof Uint8Array) s = new TextDecoder().decode(chunk)
      else if (
        typeof Buffer !== 'undefined' &&
        typeof Buffer.isBuffer === 'function' &&
        Buffer.isBuffer(chunk)
      )
        s = chunk.toString('utf8')
      else s = String(chunk)
      acc += s
      const n = acc.indexOf('\n')
      if (n >= 0) {
        cleanup()
        resolve(acc.slice(0, n).replace(/\r$/, ''))
      }
    }
    function onEnd() {
      cleanup()
      resolve(acc.replace(/\r$/, ''))
    }
    function cleanup() {
      stdin.removeListener('data', onData)
      stdin.removeListener('end', onEnd)
      stdin.removeListener('error', onEnd)
    }
    stdin.on('data', onData)
    stdin.once('end', onEnd)
    stdin.once('error', onEnd)
    if (typeof stdin.resume === 'function') stdin.resume()
  })
}

/**
 * @param {Record<string, unknown>} ctx
 * @param {import('stream').Readable} stdin
 * @param {import('stream').Writable | undefined} stdout
 * @returns {Promise<string>}
 */
function bareLoginReadMaskedLineOnce(ctx, stdin, stdout) {
  const ttyIn = /** @type {{ setRawMode?: (v: boolean) => void, isTTY?: boolean }} */ (
    stdin
  )
  if (!ttyIn || typeof ttyIn.setRawMode !== 'function' || !ttyIn.isTTY) {
    return bareLoginReadStreamLineOnce(stdin)
  }
  return new Promise((resolve, reject) => {
    /** @type {string[]} */
    const chars = []
    let done = false
    /** @param {string | Uint8Array | Buffer} chunk */
    function onData(chunk) {
      if (done) return
      let s = ''
      if (typeof chunk === 'string') s = chunk
      else if (chunk instanceof Uint8Array) s = new TextDecoder().decode(chunk)
      else if (
        typeof Buffer !== 'undefined' &&
        typeof Buffer.isBuffer === 'function' &&
        Buffer.isBuffer(chunk)
      ) {
        s = chunk.toString('utf8')
      } else s = String(chunk)
      for (const ch of s) {
        const code = ch.charCodeAt(0)
        if (ch === '\r' || ch === '\n') {
          finish(true)
          return
        }
        if (ch === '\u0003') {
          finish(false, new Error('interrupted'))
          return
        }
        if (ch === '\u007f' || ch === '\b') {
          if (chars.length) {
            chars.pop()
            bareLoginInteractiveWrite(ctx, stdout, '\b \b')
          }
          continue
        }
        if (code >= 32 && code !== 127) {
          chars.push(ch)
          bareLoginInteractiveWrite(ctx, stdout, '*')
        }
      }
    }
    /** @param {boolean} ok @param {Error} [err] */
    function finish(ok, err) {
      if (done) return
      done = true
      cleanup()
      if (ok) resolve(chars.join(''))
      else reject(err || new Error('masked_input_failed'))
    }
    function cleanup() {
      stdin.removeListener('data', onData)
      stdin.removeListener('end', onEnd)
      stdin.removeListener('error', onErr)
      try {
        ttyIn.setRawMode(false)
      } catch {
        /* ignore */
      }
      bareLoginInteractiveWrite(ctx, stdout, '\n')
    }
    function onEnd() {
      finish(true)
    }
    /** @param {unknown} e */
    function onErr(e) {
      const msg =
        e && typeof e === 'object' && 'message' in e ? String(e.message) : String(e)
      finish(false, new Error(msg))
    }
    try {
      ttyIn.setRawMode(true)
    } catch {
      return resolve('')
    }
    stdin.on('data', onData)
    stdin.once('end', onEnd)
    stdin.once('error', onErr)
    if (typeof stdin.resume === 'function') stdin.resume()
  })
}

/**
 * @param {Record<string, unknown>} ctx
 * @param {string} prompt
 * @returns {Promise<string>}
 */
async function bareLoginPromptMaskedLine(ctx, prompt) {
  const stdin = /** @type {import('stream').Readable | undefined} */ (
    ctx.replStdin || ctx.stdin
  )
  const stdout = /** @type {import('stream').Writable | undefined} */ (
    ctx.replStdout || ctx.stdout
  )
  if (!stdin || typeof stdin.on !== 'function') {
    throw new Error('login: stdin stream unavailable (need an interactive TTY)')
  }
  bareLoginInteractiveWrite(ctx, stdout, '\x1b[?25h\x1b[0m' + prompt)
  return bareLoginReadMaskedLineOnce(ctx, stdin, stdout)
}