Orginize

packages/bare-os-booter/lib/shell/shell-builtins.js

@@ -0,0 +1,224 @@
+/**
+ * Shell builtin name table and optional POSIX `read` builtin.
+ */
+
+export const SHELL_BUILTINS = new Set([
+  'alias',
+  'unalias',
+  'barerc',
+  'cd',
+  'export',
+  'unset',
+  'readonly',
+  'umask',
+  'set',
+  ':',
+  'command',
+  'type',
+  'logout',
+  'exit',
+  'jobs',
+  'fg',
+  'bg',
+  'wait',
+  'suspend-job',
+  'disown',
+  'trap',
+  'test',
+  '['
+])
+
+/**
+ * Optional POSIX-style **`read`** builtin (bounded line, IFS split). Off by default.
+ * @param {Record<string, string | undefined> | null | undefined} env
+ */
+export function bareOsShellReadBuiltinEnabled(env) {
+  const o = env && typeof env === 'object' ? env : {}
+  return o.BARE_OS_SHELL_READ_BUILTIN === '1' || o.BARE_OS_SHELL_READ_BUILTIN === 'true'
+}
+
+/**
+ * Sorted list of shell builtin command names for completion / UX.
+ * Includes **`read`** only when {@link bareOsShellReadBuiltinEnabled} is true.
+ * @param {Record<string, string | undefined> | null | undefined} env
+ * @returns {string[]}
+ */
+export function listBareOsShellBuiltins(env) {
+  const out = [...SHELL_BUILTINS]
+  if (bareOsShellReadBuiltinEnabled(env)) out.push('read')
+  out.sort()
+  return out
+}
+
+/**
+ * @param {string} cmd
+ * @param {Record<string, string | undefined> | null | undefined} env
+ */
+export function isShellBuiltin(cmd, env) {
+  if (SHELL_BUILTINS.has(cmd)) return true
+  if (cmd === 'read' && bareOsShellReadBuiltinEnabled(env)) return true
+  return false
+}
+
+/**
+ * @param {string} line
+ * @param {string} ifs
+ * @param {number} nNames
+ */
+export function bareOsShellReadSplitFields(line, ifs, nNames) {
+  const sep = ifs.length ? ifs[0] : ' '
+  if (nNames <= 1) return [line]
+  const out = []
+  let rest = line
+  for (let i = 0; i < nNames - 1; i++) {
+    const idx = rest.indexOf(sep)
+    if (idx === -1) {
+      out.push(rest)
+      rest = ''
+      break
+    }
+    out.push(rest.slice(0, idx))
+    rest = rest.slice(idx + sep.length)
+  }
+  while (out.length < nNames - 1) out.push('')
+  out.push(rest)
+  return out
+}
+
+/**
+ * @param {Record<string, unknown>} ctx
+ * @param {number} maxBytes
+ * @param {(m: string) => void} errFn
+ * @returns {Promise<string | null>} null = EOF / error
+ */
+export async function bareOsShellReadOneLine(ctx, maxBytes, errFn, opts = {}) {
+  const delimiter = typeof opts.delimiter === 'string' ? opts.delimiter : '\n'
+  const timeoutMs = Number.isFinite(opts.timeoutMs) ? Number(opts.timeoutMs) : 0
+  if (typeof ctx.shellStdin === 'string') {
+    const raw = ctx.shellStdin
+    const idx = delimiter ? raw.indexOf(delimiter) : -1
+    const line = idx === -1 ? raw : raw.slice(0, idx)
+    ctx.shellStdin = idx === -1 ? '' : raw.slice(idx + delimiter.length)
+    if (line.length > maxBytes) {
+      errFn(`read: line exceeds BARE_OS_SHELL_READ_MAX_BYTES (${maxBytes})`)
+      return null
+    }
+    return line
+  }
+  const rl = ctx.readLine
+  if (typeof rl === 'function') {
+    const readP = rl('')
+    const ln =
+      timeoutMs > 0
+        ? await Promise.race([
+            readP,
+            new Promise((resolve) => setTimeout(() => resolve(null), timeoutMs))
+          ])
+        : await readP
+    if (ln == null) return null
+    if (ln.length > maxBytes) {
+      errFn(`read: line exceeds BARE_OS_SHELL_READ_MAX_BYTES (${maxBytes})`)
+      return null
+    }
+    return ln
+  }
+  errFn(
+    'read: no input (redirect stdin, use a pipeline, or interactive readLine)'
+  )
+  return null
+}
+
+/**
+ * @param {Record<string, unknown>} ctx
+ * @param {string[]} argv
+ * @param {Record<string, string>} env
+ * @param {(m: string) => void} origErr
+ */
+export async function runShellReadBuiltin(ctx, argv, env, origErr) {
+  let i = 1
+  let rawMode = false
+  let delimiter = '\n'
+  let timeoutMs = 0
+  while (i < argv.length && argv[i].startsWith('-')) {
+    const a = argv[i]
+    if (a === '-r') {
+      rawMode = true
+    }
+    else if (a === '-d') {
+      const d = argv[i + 1]
+      if (d == null) {
+        origErr.call(ctx.console, 'read: option requires an argument -- d')
+        ctx.exitCode = 2
+        return
+      }
+      delimiter = String(d).slice(0, 1)
+      i++
+    }
+    else if (a === '-t') {
+      const v = argv[i + 1]
+      if (v == null) {
+        origErr.call(ctx.console, 'read: option requires an argument -- t')
+        ctx.exitCode = 2
+        return
+      }
+      const n = Number.parseFloat(String(v))
+      if (!Number.isFinite(n) || n < 0) {
+        origErr.call(ctx.console, 'read: invalid timeout: ' + String(v))
+        ctx.exitCode = 2
+        return
+      }
+      timeoutMs = Math.min(Math.floor(n * 1000), 120000)
+      i++
+    }
+    else if (a === '--') {
+      i++
+      break
+    } else {
+      origErr.call(ctx.console, 'read: unsupported option: ' + a)
+      ctx.exitCode = 2
+      return
+    }
+    i++
+  }
+  const names = argv.slice(i).filter(Boolean)
+  if (!names.length) names.push('REPLY')
+  const maxRaw = env.BARE_OS_SHELL_READ_MAX_BYTES
+  const maxParsed =
+    maxRaw != null && String(maxRaw).trim() !== ''
+      ? Number.parseInt(String(maxRaw), 10)
+      : 65536
+  const maxBytes =
+    Number.isFinite(maxParsed) && maxParsed > 0
+      ? Math.min(maxParsed, 2_000_000)
+      : 65536
+  let line = await bareOsShellReadOneLine(
+    ctx,
+    maxBytes,
+    (m) => origErr.call(ctx.console, m),
+    { delimiter, timeoutMs }
+  )
+  if (line === null) {
+    for (const n of names) env[n] = ''
+    ctx.exitCode = 1
+    return
+  }
+  if (!rawMode) {
+    line = line.replace(/\\(.)/g, '$1')
+  }
+  const ifs =
+    env.IFS !== undefined && env.IFS !== null ? String(env.IFS) : ' \t\n'
+  const fields = bareOsShellReadSplitFields(line, ifs, names.length)
+  for (let j = 0; j < names.length; j++) {
+    const k = names[j]
+    if (
+      ctx.shellReadonlyVars instanceof Set &&
+      ctx.shellReadonlyVars.has(k)
+    ) {
+      origErr.call(ctx.console, k + ': readonly variable')
+      ctx.exitCode = 1
+      return
+    }
+    env[k] = fields[j] ?? ''
+  }
+  ctx.exitCode = 0
+}