fix: metadata file error in FileResourceStore

* Fix: metadata file error in FileResourceStore

* fix: ensure full test coverage

* add stream piping function in util

* Fix typing in util function

* Add requested changes

* add suggested changes

* add suggested change

Co-authored-by: freyavs <freyavanspeybroeck@outlook.com>

src/storage/FileResourceStore.ts

@@ -1,7 +1,6 @@
 import { createReadStream, createWriteStream, promises as fsPromises, Stats } from 'fs';
 import { posix } from 'path';
 import { Readable } from 'stream';
-import arrayifyStream from 'arrayify-stream';
 import { contentType as getContentTypeFromExtension } from 'mime-types';
 import { Quad } from 'rdf-js';
 import streamifyArray from 'streamify-array';
@@ -69,7 +68,7 @@ export class FileResourceStore implements ResourceStore {
     const linkTypes = representation.metadata.linkRel?.type;
     let metadata;
     if (raw.length > 0) {
-      metadata = this.metadataController.generateReadableFromQuads(raw);
+      metadata = this.metadataController.serializeQuads(raw);
     }
 
     // Create a new container or resource in the parent container with a specific name based on the incoming headers.
@@ -252,7 +251,7 @@ export class FileResourceStore implements ResourceStore {
     let rawMetadata: Quad[] = [];
     try {
       const readMetadataStream = createReadStream(`${path}.metadata`);
-      rawMetadata = await this.metadataController.generateQuadsFromReadable(readMetadataStream);
+      rawMetadata = await this.metadataController.parseQuads(readMetadataStream);
     } catch (_) {
       // Metadata file doesn't exist so lets keep `rawMetaData` an empty array.
     }
@@ -289,7 +288,7 @@ export class FileResourceStore implements ResourceStore {
     let rawMetadata: Quad[] = [];
     try {
       const readMetadataStream = createReadStream(joinPath(path, '.metadata'));
-      rawMetadata = await arrayifyStream(readMetadataStream);
+      rawMetadata = await this.metadataController.parseQuads(readMetadataStream);
     } catch (_) {
       // Metadata file doesn't exist so lets keep `rawMetaData` an empty array.
     }

src/storage/conversion/RdfToQuadConverter.ts

@@ -3,7 +3,7 @@ import rdfParser from 'rdf-parse';
 import { Representation } from '../../ldp/representation/Representation';
 import { RepresentationMetadata } from '../../ldp/representation/RepresentationMetadata';
 import { INTERNAL_QUADS } from '../../util/ContentTypes';
-import { UnsupportedHttpError } from '../../util/errors/UnsupportedHttpError';
+import { pipeStreamsAndErrors } from '../../util/Util';
 import { checkRequest } from './ConversionUtil';
 import { RepresentationConverterArgs } from './RepresentationConverter';
 import { TypedRepresentationConverter } from './TypedRepresentationConverter';
@@ -30,20 +30,19 @@ export class RdfToQuadConverter extends TypedRepresentationConverter {
 
   private rdfToQuads(representation: Representation, baseIRI: string): Representation {
     const metadata: RepresentationMetadata = { ...representation.metadata, contentType: INTERNAL_QUADS };
-
-    // Catch parsing errors and emit correct error
-    // Node 10 requires both writableObjectMode and readableObjectMode
-    const errorStream = new PassThrough({ writableObjectMode: true, readableObjectMode: true });
-    const data = rdfParser.parse(representation.data, {
+    const rawQuads = rdfParser.parse(representation.data, {
       contentType: representation.metadata.contentType as string,
       baseIRI,
     });
-    data.pipe(errorStream);
-    data.on('error', (error): boolean => errorStream.emit('error', new UnsupportedHttpError(error.message)));
+
+    // Wrap the stream such that errors are transformed
+    // (Node 10 requires both writableObjectMode and readableObjectMode)
+    const data = new PassThrough({ writableObjectMode: true, readableObjectMode: true });
+    pipeStreamsAndErrors(rawQuads, data);
 
     return {
       binary: false,
-      data: errorStream,
+      data,
       metadata,
     };
   }

src/util/MetadataController.ts

@@ -6,6 +6,7 @@ import { NamedNode, Quad } from 'rdf-js';
 import streamifyArray from 'streamify-array';
 import { TEXT_TURTLE } from '../util/ContentTypes';
 import { LDP, RDF, STAT, TERMS, XML } from './Prefixes';
+import { pipeStreamsAndErrors } from './Util';
 
 export const TYPE_PREDICATE = DataFactory.namedNode(`${RDF}type`);
 export const MODIFIED_PREDICATE = DataFactory.namedNode(`${TERMS}modified`);
@@ -64,13 +65,13 @@ export class MetadataController {
   }
 
   /**
-   * Helper function to convert an array of quads into a Readable object.
+   * Helper function for serializing an array of quads, with as result a Readable object.
    * @param quads - The array of quads.
    *
    * @returns The Readable object.
    */
-  public generateReadableFromQuads(quads: Quad[]): Readable {
-    return streamifyArray(quads).pipe(new StreamWriter({ format: TEXT_TURTLE }));
+  public serializeQuads(quads: Quad[]): Readable {
+    return pipeStreamsAndErrors(streamifyArray(quads), new StreamWriter({ format: TEXT_TURTLE }));
   }
 
   /**
@@ -79,7 +80,7 @@ export class MetadataController {
    *
    * @returns A promise containing the array of quads.
    */
-  public async generateQuadsFromReadable(readable: Readable): Promise<Quad[]> {
-    return arrayifyStream(readable.pipe(new StreamParser({ format: TEXT_TURTLE })));
+  public async parseQuads(readable: Readable): Promise<Quad[]> {
+    return await arrayifyStream(pipeStreamsAndErrors(readable, new StreamParser({ format: TEXT_TURTLE })));
   }
 }

src/util/Util.ts

@@ -1,5 +1,6 @@
-import { Readable } from 'stream';
+import { Readable, Writable } from 'stream';
 import arrayifyStream from 'arrayify-stream';
+import { UnsupportedHttpError } from './errors/UnsupportedHttpError';
 
 /**
  * Makes sure the input path has exactly 1 slash at the end.
@@ -51,3 +52,17 @@ export const matchingMediaType = (mediaA: string, mediaB: string): boolean => {
   }
   return subTypeA === subTypeB;
 };
+
+/**
+ * Pipes one stream into another.
+ * Makes sure an error of the first stream gets passed to the second.
+ * @param readable - Initial readable stream.
+ * @param destination - The destination for writing data.
+ *
+ * @returns The destination stream.
+ */
+export const pipeStreamsAndErrors = <T extends Writable>(readable: Readable, destination: T): T => {
+  readable.pipe(destination);
+  readable.on('error', (error): boolean => destination.emit('error', new UnsupportedHttpError(error.message)));
+  return destination;
+};

test/unit/storage/FileResourceStore.test.ts

@@ -205,7 +205,7 @@ describe('A FileResourceStore', (): void => {
     stats.isFile = jest.fn((): any => true);
     (fsPromises.lstat as jest.Mock).mockReturnValueOnce(stats);
     (fs.createReadStream as jest.Mock).mockReturnValueOnce(streamifyArray([ rawData ]));
-    (fs.createReadStream as jest.Mock).mockImplementationOnce((): any => new Error('Metadata file does not exist.'));
+    (fs.createReadStream as jest.Mock).mockReturnValueOnce(streamifyArray([]));
 
     // Tests
     await store.setRepresentation({ path: `${base}file.txt` }, representation);
@@ -488,7 +488,8 @@ describe('A FileResourceStore', (): void => {
     stats.isFile = jest.fn((): any => true);
     (fsPromises.lstat as jest.Mock).mockReturnValueOnce(stats);
     (fs.createReadStream as jest.Mock).mockReturnValueOnce(streamifyArray([ rawData ]));
-    (fs.createReadStream as jest.Mock).mockImplementationOnce((): any => new Error('Metadata file does not exist.'));
+    (fs.createReadStream as jest.Mock).mockReturnValueOnce(new Readable()
+      .destroy(new Error('Metadata file does not exist.')));
 
     const result = await store.getRepresentation({ path: `${base}.htaccess` });
     expect(result).toEqual({