New utils

kernel/bin/tsort

@@ -0,0 +1,165 @@
+/* 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
+}
+
+async function run(ctx, argv) {
+  const paths = []
+  for (let i = 1; i < argv.length; i++) {
+    const a = argv[i]
+    if (a === '-h' || a === '--help') {
+      ctx.console.log(
+        'usage: tsort [FILE]\nTopological sort of directed edges (one pair per line: A B).'
+      )
+      return
+    }
+    if (a.startsWith('-')) {
+      ctx.console.error('tsort: unsupported option ' + a)
+      ctx.exitCode = 1
+      return
+    }
+    paths.push(a)
+  }
+  const b4 = ctx.b4a
+  let text
+  if (!paths.length || paths[0] === '-') text = bareStdin(ctx)
+  else {
+    const b = await ctx.vfs.readFile(paths[0])
+    if (!b) {
+      ctx.console.error('tsort: cannot read ' + paths[0])
+      ctx.exitCode = 1
+      return
+    }
+    text = b4.toString(b)
+  }
+  const edges = []
+  const nodes = new Set()
+  for (const line of text.split('\n')) {
+    const t = line.trim()
+    if (!t) continue
+    const parts = t.split(/\s+/)
+    if (parts.length < 2) continue
+    const u = parts[0]
+    const v = parts[1]
+    edges.push([u, v])
+    nodes.add(u)
+    nodes.add(v)
+  }
+  const indeg = new Map()
+  const adj = new Map()
+  for (const n of nodes) {
+    indeg.set(n, 0)
+    adj.set(n, [])
+  }
+  for (const [u, v] of edges) {
+    indeg.set(v, (indeg.get(v) || 0) + 1)
+    adj.get(u).push(v)
+  }
+  const q = []
+  for (const [n, d] of indeg) {
+    if (d === 0) q.push(n)
+  }
+  q.sort()
+  const out = []
+  while (q.length) {
+    const u = q.shift()
+    out.push(u)
+    for (const v of adj.get(u) || []) {
+      indeg.set(v, indeg.get(v) - 1)
+      if (indeg.get(v) === 0) {
+        q.push(v)
+        q.sort()
+      }
+    }
+  }
+  if (out.length !== nodes.size) {
+    ctx.console.error('tsort: cycle in input')
+    ctx.exitCode = 1
+    return
+  }
+  for (const n of out) ctx.console.log(n)
+}