feat: Add access methods that translate errors into issues

Author: effigies

src/files/access.test.ts

@@ -0,0 +1,36 @@
+import { assert, assertObjectMatch } from '@std/assert'
+import { basename, dirname } from '@std/path'
+import { BIDSFileDeno } from './deno.ts'
+
+export function testAsyncFileAccess(
+  name: string,
+  fn: (file: BIDSFileDeno, ...args: any[]) => Promise<any>,
+  ...args: any[]
+) {
+  Deno.test(name, async (t) => {
+    await t.step('Dangling symlink', async () => {
+      const file = new BIDSFileDeno('tests/data', '/broken-symlink')
+      try {
+        await fn(file, ...args)
+        assert(false, 'Expected error')
+      } catch (e: any) {
+        assertObjectMatch(e, {
+          code: 'FILE_READ',
+          subCode: 'NotFound',
+          location: '/broken-symlink',
+        })
+      }
+    })
+    await t.step('Insufficient permissions', async () => {
+      const tmpfile = await Deno.makeTempFile()
+      await Deno.chmod(tmpfile, 0o000)
+      const file = new BIDSFileDeno('', tmpfile)
+      try {
+        await fn(file, ...args)
+        assert(false, 'Expected error')
+      } catch (e: any) {
+        assertObjectMatch(e, { code: 'FILE_READ', subCode: 'PermissionDenied' })
+      }
+    })
+  })
+}

src/files/access.ts

@@ -0,0 +1,35 @@
+import { type BIDSFile } from '../types/filetree.ts'
+import { type Issue } from '../types/issues.ts'
+
+function IOErrorToIssue(err: { code: string; name: string }): Issue {
+  const subcode = err.name
+  let issueMessage: string | undefined = undefined
+  if (err.code === 'ENOENT') {
+    issueMessage = 'Possible dangling symbolic link'
+  }
+  return { code: 'FILE_READ', subCode: err.name, issueMessage }
+}
+
+export function openStream(file: BIDSFile): ReadableStream<Uint8Array<ArrayBuffer>> {
+  try {
+    return file.stream
+  } catch (err: any) {
+    throw { location: file.path, ...IOErrorToIssue(err) }
+  }
+}
+
+export async function readBytes(
+  file: BIDSFile,
+  size: number,
+  offset = 0,
+): Promise<Uint8Array<ArrayBuffer>> {
+  return file.readBytes(size, offset).catch((err: any) => {
+    throw { location: file.path, ...IOErrorToIssue(err) }
+  })
+}
+
+export async function readText(file: BIDSFile): Promise<string> {
+  return file.text().catch((err: any) => {
+    throw { location: file.path, ...IOErrorToIssue(err) }
+  })
+}

tests/data/broken-symlink

@@ -0,0 +1 @@
+dangling-target