bare-operating-system/kernel/bin/printf

/* BARE_OS_BIN_API 1.0.0 — bump when staged /bin script semantics change (see developer guide). */
/** Shared helpers for drive-resident /bin scripts (prepended before each command). */
function bareStdin(ctx) {
  return typeof ctx.shellStdin === 'string' ? ctx.shellStdin : ''
}

/** @param {number} mode @param {'file' | 'directory' | 'symlink'} type */
function bareFormatModeString(mode, type) {
  const typeChar = type === 'directory' ? 'd' : type === 'symlink' ? 'l' : '-'
  const perm = mode & 0o777
  const r = (bit) => (perm & bit ? 'r' : '-')
  const w = (bit) => (perm & bit ? 'w' : '-')
  const x = (bit) => (perm & bit ? 'x' : '-')
  return (
    typeChar +
    r(0o400) +
    w(0o200) +
    x(0o100) +
    r(0o040) +
    w(0o020) +
    x(0o010) +
    r(0o004) +
    w(0o002) +
    x(0o001)
  )
}

/** @param {number} mtimeMs @param {number} [nowMs] */
function bareFormatLsMtime(mtimeMs, nowMs) {
  const now = nowMs != null ? nowMs : Date.now()
  const d = new Date(mtimeMs)
  const months = [
    'Jan',
    'Feb',
    'Mar',
    'Apr',
    'May',
    'Jun',
    'Jul',
    'Aug',
    'Sep',
    'Oct',
    'Nov',
    'Dec'
  ]
  const mon = months[d.getMonth()]
  const day = String(d.getDate()).padStart(2, ' ')
  const sixMo = 180 * 24 * 3600 * 1000
  if (Math.abs(now - mtimeMs) > sixMo) {
    const yr = String(d.getFullYear()).padStart(4, ' ')
    return mon + ' ' + day + '  ' + yr
  }
  const hh = String(d.getHours()).padStart(2, '0')
  const mm = String(d.getMinutes()).padStart(2, '0')
  return mon + ' ' + day + ' ' + hh + ':' + mm
}

/** @param {number} size */
function barePosixBlocks(size) {
  return Math.ceil(Number(size) / 512) || 0
}

/**
 * Raw stdout for NUL/binary when **`process.stdout.write`** is missing.
 * If **`ctx.bareOsBinWrite(Uint8Array|string)`** is set (tests / host), use it.
 * @param {Record<string, unknown>} ctx
 * @param {string | Uint8Array} chunk
 * @returns {boolean}
 */
function bareOsEmitRaw(ctx, chunk) {
  if (typeof ctx.bareOsBinWrite === 'function') {
    const b4 = ctx.b4a
    const u8 =
      typeof chunk === 'string'
        ? b4 && typeof b4.from === 'function'
          ? b4.from(chunk)
          : new TextEncoder().encode(chunk)
        : chunk
    ctx.bareOsBinWrite(u8 instanceof Uint8Array ? u8 : new Uint8Array(u8))
    return true
  }
  const w = globalThis.process?.stdout?.write
  if (typeof w === 'function') {
    w.call(globalThis.process.stdout, chunk)
    return true
  }
  return false
}

/** Unescape \\n \\t \\r \\\\ and octal \\ddd inside FORMAT (POSIX-style subset). */
function barePrintfUnescapeFormat(fmt) {
  let o = ''
  for (let i = 0; i < fmt.length; i++) {
    if (fmt[i] !== '\\') {
      o += fmt[i]
      continue
    }
    const c = fmt[++i]
    if (c === undefined) break
    if (c === 'n') o += '\n'
    else if (c === 't') o += '\t'
    else if (c === 'r') o += '\r'
    else if (c === '\\') o += '\\'
    else if (c >= '0' && c <= '7') {
      let oct = c
      while (i + 1 < fmt.length && /[0-7]/.test(fmt[i + 1]) && oct.length < 3)
        oct += fmt[++i]
      o += String.fromCharCode(Number.parseInt(oct, 8) & 0xff)
    } else o += c
  }
  return o
}

/** @param {string} s */
function barePrintfBackslashArg(s) {
  let o = ''
  for (let i = 0; i < s.length; i++) {
    if (s[i] !== '\\') {
      o += s[i]
      continue
    }
    const c = s[++i]
    if (c === undefined) break
    if (c === 'n') o += '\n'
    else if (c === 't') o += '\t'
    else if (c === 'r') o += '\r'
    else if (c === '\\') o += '\\'
    else if (c >= '0' && c <= '7') {
      let oct = c
      while (i + 1 < s.length && /[0-7]/.test(s[i + 1]) && oct.length < 3)
        oct += s[++i]
      o += String.fromCharCode(Number.parseInt(oct, 8) & 0xff)
    } else o += c
  }
  return o
}

/** Left-pad to width (capped); spaces or ASCII zero. */
function barePrintfPadLeft(s, width, zero) {
  const n = Math.min(Math.max(0, width | 0), 256)
  if (!n || s.length >= n) return s
  const pad = zero ? '0' : ' '
  return pad.repeat(n - s.length) + s
}

function barePrintfFormat(fmt, args) {
  let ai = 0
  let o = ''
  for (let i = 0; i < fmt.length; i++) {
    if (fmt[i] !== '%') {
      o += fmt[i]
      continue
    }
    if (fmt[i + 1] === '%') {
      o += '%'
      i++
      continue
    }
    let j = i + 1
    let zeroPad = false
    if (fmt[j] === '0') {
      zeroPad = true
      j++
    }
    let width = 0
    while (j < fmt.length && fmt[j] >= '0' && fmt[j] <= '9') {
      width = Math.min(width * 10 + (fmt[j].charCodeAt(0) - 48), 256)
      j++
    }
    while (j < fmt.length && /[.#\-+ ]/.test(fmt[j])) j++
    const spec = fmt[j] || 's'
    const arg = args[ai++]
    let piece = ''
    if (spec === 's') piece = String(arg)
    else if (spec === 'd' || spec === 'i')
      piece = String(Math.trunc(Number(arg)))
    else if (spec === 'u') piece = String(Math.trunc(Number(arg)) >>> 0)
    else if (spec === 'x') piece = (Math.trunc(Number(arg)) >>> 0).toString(16)
    else if (spec === 'X')
      piece = (Math.trunc(Number(arg)) >>> 0).toString(16).toUpperCase()
    else if (spec === 'o') piece = (Math.trunc(Number(arg)) >>> 0).toString(8)
    else if (spec === 'c') {
      const a0 = arg
      piece =
        typeof a0 === 'string' && a0.length > 0
          ? a0[0]
          : String.fromCharCode(Number(a0) || 0)
    } else if (spec === 'f') piece = String(Number(arg))
    else if (spec === 'e') piece = Number(arg).toExponential(6)
    else if (spec === 'E')
      piece = Number(arg).toExponential(6).replace(/e/g, 'E')
    else if (spec === 'b') piece = barePrintfBackslashArg(String(arg))
    else piece = String(arg)

    if (
      width > 0 &&
      (spec === 'd' ||
        spec === 'i' ||
        spec === 'u' ||
        spec === 'x' ||
        spec === 'X' ||
        spec === 'o')
    ) {
      if (zeroPad && piece.startsWith('-')) {
        o += '-' + barePrintfPadLeft(piece.slice(1), width - 1, true)
      } else {
        o += barePrintfPadLeft(piece, width, zeroPad)
      }
    } else if (width > 0 && spec === 's') {
      o += barePrintfPadLeft(piece, width, false)
    } else {
      o += piece
    }
    i = j
  }
  return o
}

async function run(ctx, argv) {
  if (argv.length < 2) {
    ctx.console.error('usage: printf FORMAT [ARG...]')
    ctx.exitCode = 1
    return
  }
  const fmt = argv[1]
  const args = argv.slice(2)
  const unescaped = barePrintfUnescapeFormat(fmt)
  ctx.console.log(barePrintfFormat(unescaped, args))
}