dsh 0.2.0-rc.2: in-container update (experimental channel), path-agnostic compose, upstream patches adapted to 0.1.x/0.2.x

upstream/container/control-plane/services/management/settings-document.mjs

@@ -0,0 +1,82 @@
+import { createHash, randomUUID } from 'node:crypto'
+import { chown, lstat, mkdir, readFile, rename, rm, stat, writeFile } from 'node:fs/promises'
+import { dirname, join, resolve } from 'node:path'
+
+export const MAX_SETTINGS_DOCUMENT_BYTES = 1024 * 1024
+const UTF8 = new TextDecoder('utf-8', { fatal: true })
+
+function revision(bytes) {
+  return createHash('sha256').update(bytes).digest('hex')
+}
+
+function assertRegularFile(details) {
+  if (details.isSymbolicLink() || !details.isFile()) {
+    throw new Error('settings document must be a regular file')
+  }
+}
+
+export class SettingsDocumentConflictError extends Error {}
+
+export class SettingsDocumentStore {
+  constructor(dshHome, { maxBytes = MAX_SETTINGS_DOCUMENT_BYTES } = {}) {
+    this.dshHome = resolve(dshHome)
+    this.path = join(this.dshHome, 'settings.yaml')
+    this.maxBytes = maxBytes
+  }
+
+  async read() {
+    let details
+    try {
+      details = await lstat(this.path)
+    } catch (error) {
+      if (error?.code === 'ENOENT') {
+        const bytes = Buffer.alloc(0)
+        return Object.freeze({ content: '', revision: revision(bytes), exists: false })
+      }
+      throw error
+    }
+    assertRegularFile(details)
+    if (details.size > this.maxBytes) throw new Error('settings document is too large')
+    const bytes = await readFile(this.path)
+    if (bytes.byteLength > this.maxBytes) throw new Error('settings document is too large')
+    let content
+    try {
+      content = UTF8.decode(bytes)
+    } catch {
+      throw new Error('settings document is not valid UTF-8')
+    }
+    return Object.freeze({ content, revision: revision(bytes), exists: true })
+  }
+
+  async write(content, expectedRevision) {
+    if (typeof content !== 'string') throw new Error('settings document content must be a string')
+    if (typeof expectedRevision !== 'string' || !/^[a-f0-9]{64}$/.test(expectedRevision)) {
+      throw new Error('settings document revision is invalid')
+    }
+    const bytes = Buffer.from(content)
+    if (bytes.byteLength > this.maxBytes) throw new Error('settings document is too large')
+    const current = await this.read()
+    if (current.revision !== expectedRevision) {
+      throw new SettingsDocumentConflictError('settings document changed since it was loaded')
+    }
+
+    await mkdir(this.dshHome, { recursive: true, mode: 0o700 })
+    const owner = current.exists ? await lstat(this.path) : await stat(this.dshHome)
+    if (current.exists) assertRegularFile(owner)
+    const temporary = join(this.dshHome, `.settings.yaml.${randomUUID()}.tmp`)
+    try {
+      await writeFile(temporary, bytes, {
+        flag: 'wx',
+        mode: current.exists ? owner.mode & 0o777 : 0o600,
+      })
+      if (process.getuid?.() === 0) await chown(temporary, owner.uid, owner.gid)
+      if ((await this.read()).revision !== expectedRevision) {
+        throw new SettingsDocumentConflictError('settings document changed while it was being saved')
+      }
+      await rename(temporary, this.path)
+    } finally {
+      await rm(temporary, { force: true })
+    }
+    return Object.freeze({ content, revision: revision(bytes), exists: true })
+  }
+}