bare-operating-system/packages/bare-os-seeder/kernel/bin/xargs

/* 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
}

/**
 * Bounded xargs for Bare OS: invokes ctx.runBinCommand only (no host spawn).
 * Limits: stdin 256KiB, 4096 whitespace/null tokens, 128 args per invocation,
 * 64 invocations per run. Exceeding limits is a fatal error (exit 125).
 * Supports -0/--null, -n, -I repl (replace repl in utility argv; implies -n 1 unless -n given).
 * -P N runs up to N batches in parallel (each batch uses a shallow ctx clone so exitCode does not race).
 * Max -P is min(requested, BARE_OS_XARGS_MAX_PROCS env, 32); default cap 8 when env unset.
 */

const MAX_STDIN = 256 * 1024
const MAX_TOKENS = 4096
const MAX_PER_INVOCATION = 128
const MAX_INVOCATIONS = 64
const DEFAULT_P_CAP = 8
const ABS_P_CAP = 32

/**
 * @param {Record<string, unknown>} ctx
 */
function maxParallelFromEnv(ctx) {
  const env = (ctx && ctx.vfs && ctx.vfs.env) || (ctx && ctx.env) || {}
  const raw = String(env.BARE_OS_XARGS_MAX_PROCS || '').trim()
  if (!raw || !/^\d+$/.test(raw)) return DEFAULT_P_CAP
  const n = Number(raw)
  return Math.min(ABS_P_CAP, Math.max(1, n))
}

async function run(ctx, argv) {
  if (typeof ctx.runBinCommand !== 'function') {
    ctx.console.error(
      'xargs: ctx.runBinCommand is not available (requires a Bare OS booter session)'
    )
    ctx.exitCode = 1
    return
  }
  const args = argv.slice(1)
  let nullSep = false
  let maxBatch = MAX_PER_INVOCATION
  /** @type {string | null} */
  let repl = null
  let nExplicit = false
  const envPCap = maxParallelFromEnv(ctx)
  let pCap = 1
  let i = 0

  while (i < args.length && args[i].startsWith('-')) {
    const a = args[i]
    if (a === '--') {
      i++
      break
    }
    if (a === '-0' || a === '--null') {
      nullSep = true
      i++
      continue
    }
    if (a === '-P' || a === '--max-procs') {
      const n = args[i + 1]
      if (n == null || !/^\d+$/.test(n)) {
        ctx.console.error('xargs: -P requires a non-negative integer')
        ctx.exitCode = 1
        return
      }
      const raw = Number(n)
      pCap = Math.min(envPCap, Math.max(1, raw))
      if (raw > envPCap) {
        ctx.console.error(
          'xargs: -P ' +
            raw +
            ' exceeds cap ' +
            envPCap +
            ' (raise BARE_OS_XARGS_MAX_PROCS up to ' +
            ABS_P_CAP +
            ')'
        )
      }
      i += 2
      continue
    }
    if (a.startsWith('-P') && a.length > 2 && /^\d+$/.test(a.slice(2))) {
      const raw = Number(a.slice(2))
      pCap = Math.min(envPCap, Math.max(1, raw))
      if (raw > envPCap) {
        ctx.console.error(
          'xargs: -P exceeds cap ' +
            envPCap +
            ' (raise BARE_OS_XARGS_MAX_PROCS up to ' +
            ABS_P_CAP +
            ')'
        )
      }
      i++
      continue
    }
    if (a === '-n' || a === '--max-args') {
      const n = args[i + 1]
      if (n == null || !/^\d+$/.test(n) || Number(n) < 1) {
        ctx.console.error('xargs: -n requires a positive integer')
        ctx.exitCode = 1
        return
      }
      maxBatch = Math.min(Number(n), MAX_PER_INVOCATION)
      nExplicit = true
      i += 2
      continue
    }
    if (a.startsWith('-n') && a.length > 2 && /^\d+$/.test(a.slice(2))) {
      const n = Number(a.slice(2))
      maxBatch = Math.min(n, MAX_PER_INVOCATION)
      nExplicit = true
      i++
      continue
    }
    if (a === '-I' || a === '-i') {
      repl = args[i + 1] != null ? String(args[i + 1]) : '{}'
      i += 2
      if (!nExplicit) maxBatch = 1
      continue
    }
    if (
      (a.startsWith('-I') || a.startsWith('-i')) &&
      a.length > 2 &&
      a[2] !== '-'
    ) {
      repl = a.slice(2) || '{}'
      i++
      if (!nExplicit) maxBatch = 1
      continue
    }
    ctx.console.error('xargs: unsupported option: ' + a)
    ctx.console.error(
      'xargs: Bare OS supports: -0/--null, -n N (max ' +
        MAX_PER_INVOCATION +
        ' per run), -I repl, -P N (parallel batches, cap ' +
        envPCap +
        ')'
    )
    ctx.exitCode = 1
    return
  }

  /** @type {string[]} */
  let cmd = args.slice(i)
  if (cmd.length === 0) cmd = ['echo']

  let text = bareStdin(ctx) || ''
  if (text.length > MAX_STDIN) {
    ctx.console.error(
      'xargs: stdin exceeds ' + MAX_STDIN + ' bytes (Bare OS limit)'
    )
    ctx.exitCode = 125
    return
  }

  /** @type {string[]} */
  let pieces
  if (nullSep) {
    pieces = text.split('\0').filter((s) => s.length > 0)
  } else {
    pieces = text.trim() === '' ? [] : text.trim().split(/\s+/).filter(Boolean)
  }

  if (pieces.length > MAX_TOKENS) {
    ctx.console.error(
      'xargs: too many arguments (' + pieces.length + ' > ' + MAX_TOKENS + ')'
    )
    ctx.exitCode = 125
    return
  }

  /**
   * @param {Record<string, unknown>} target
   * @param {string[]} batch
   */
  const runOne = async (target, batch) => {
    const subst = batch.join(' ')
    /** @type {string[]} */
    const toRun =
      repl == null
        ? cmd.concat(batch)
        : cmd.map((c) => {
            let o = c
            let guard = 0
            while (o.includes(repl) && guard < 4096) {
              o = o.split(repl).join(subst)
              guard++
            }
            return o
          })
    await target.runBinCommand(toRun)
  }

  if (pieces.length === 0) {
    await runOne(ctx, [])
    return
  }

  /** @type {string[][]} */
  const batches = []
  for (let o = 0; o < pieces.length; o += maxBatch) {
    if (batches.length >= MAX_INVOCATIONS) {
      ctx.console.error(
        'xargs: exceeded ' + MAX_INVOCATIONS + ' invocations (Bare OS limit)'
      )
      ctx.exitCode = 125
      return
    }
    batches.push(pieces.slice(o, o + maxBatch))
  }

  if (pCap <= 1) {
    for (const batch of batches) {
      await runOne(ctx, batch)
      if ((Number(ctx.exitCode) || 0) !== 0) return
    }
    return
  }

  for (let w = 0; w < batches.length; w += pCap) {
    const slice = batches.slice(w, w + pCap)
    const codes = await Promise.all(
      slice.map(async (batch) => {
        const c = Object.assign({}, ctx, { exitCode: 0 })
        await runOne(c, batch)
        return Number(c.exitCode) || 0
      })
    )
    const bad = codes.find((x) => x !== 0)
    if (bad != null) {
      ctx.exitCode = bad
      return
    }
  }
  ctx.exitCode = 0
}