fix: prevent JsonResourceStorage from generating too long filenames

src/storage/keyvalue/JsonResourceStorage.ts

@@ -1,13 +1,19 @@
+import { createHash } from 'crypto';
+import { parse } from 'path';
 import { BasicRepresentation } from '../../http/representation/BasicRepresentation';
 import type { Representation } from '../../http/representation/Representation';
 import type { ResourceIdentifier } from '../../http/representation/ResourceIdentifier';
 import { NotFoundHttpError } from '../../util/errors/NotFoundHttpError';
-import { ensureLeadingSlash, ensureTrailingSlash, isContainerIdentifier, joinUrl } from '../../util/PathUtil';
+import { ensureLeadingSlash, ensureTrailingSlash, isContainerIdentifier, joinUrl,
+  joinFilePath } from '../../util/PathUtil';
 import { readableToString } from '../../util/StreamUtil';
 import { LDP } from '../../util/Vocabularies';
 import type { ResourceStore } from '../ResourceStore';
 import type { KeyValueStorage } from './KeyValueStorage';
 
+// Maximum allowed length for the keys, longer keys will be hashed.
+const KEY_LENGTH_LIMIT = 255;
+
 /**
  * A {@link KeyValueStorage} for JSON-like objects using a {@link ResourceStore} as backend.
  *
@@ -114,6 +120,15 @@ export class JsonResourceStorage<T> implements KeyValueStorage<string, T> {
    * Converts a key into an identifier for internal storage.
    */
   private keyToIdentifier(key: string): ResourceIdentifier {
+    // Parse the key as a file path
+    const parsedPath = parse(key);
+    // Hash long filenames to prevent issues with the underlying storage.
+    // E.g. a UNIX a file name cannot exceed 255 bytes.
+    // This is a temporary fix for https://github.com/CommunitySolidServer/CommunitySolidServer/issues/1013,
+    // until we have a solution for data migration.
+    if (parsedPath.base.length > KEY_LENGTH_LIMIT) {
+      key = joinFilePath(parsedPath.dir, this.applyHash(parsedPath.base));
+    }
     return { path: joinUrl(this.container, key) };
   }
 
@@ -127,4 +142,8 @@ export class JsonResourceStorage<T> implements KeyValueStorage<string, T> {
     // on the `entries` results matching a key that was sent before.
     return ensureLeadingSlash(identifier.path.slice(this.container.length));
   }
+
+  private applyHash(key: string): string {
+    return createHash('sha256').update(key).digest('hex');
+  }
 }

test/unit/storage/keyvalue/JsonResourceStorage.test.ts

@@ -1,3 +1,4 @@
+import { createHash } from 'crypto';
 import { BasicRepresentation } from '../../../../src/http/representation/BasicRepresentation';
 import type { Representation } from '../../../../src/http/representation/Representation';
 import { RepresentationMetadata } from '../../../../src/http/representation/RepresentationMetadata';
@@ -5,7 +6,7 @@ import type { ResourceIdentifier } from '../../../../src/http/representation/Res
 import { JsonResourceStorage } from '../../../../src/storage/keyvalue/JsonResourceStorage';
 import type { ResourceStore } from '../../../../src/storage/ResourceStore';
 import { NotFoundHttpError } from '../../../../src/util/errors/NotFoundHttpError';
-import { isContainerIdentifier } from '../../../../src/util/PathUtil';
+import { isContainerIdentifier, joinUrl } from '../../../../src/util/PathUtil';
 import { readableToString } from '../../../../src/util/StreamUtil';
 import { LDP } from '../../../../src/util/Vocabularies';
 
@@ -123,7 +124,23 @@ describe('A JsonResourceStorage', (): void => {
     ]);
   });
 
-  it('can handle resources being deleted while iterating in the entries call.', async(): Promise<void> => {
-    //
-  });
+  it('converts keys that would result in too large filenames into an identifier that uses a hash.',
+    async(): Promise<void> => {
+      const longFileName = `${'sometext'.repeat(32)}.json`;
+      const b64LongFileName = Buffer.from(longFileName).toString('base64');
+      const longKey = `/container/${b64LongFileName}`;
+      const longKeyId = joinUrl(subContainerIdentifier, createHash('sha256').update(b64LongFileName).digest('hex'));
+
+      await storage.set(longKey, 'data');
+      // Check if a hash of the key has been used for the filename part of the key.
+      expect(data.has(longKeyId)).toBeTruthy();
+
+      data.clear();
+
+      // Check that normal keys stay unaffected
+      const normalKey = '/container/test';
+      const normalKeyId = joinUrl(containerIdentifier, normalKey);
+      await storage.set(normalKey, 'data');
+      expect(data.has(normalKeyId)).toBeTruthy();
+    });
 });