Include metadata length in metadata

package.json

@@ -27,14 +27,14 @@
     "typecheck": "tsc"
   },
   "devDependencies": {
-    "@types/node": "20.10.8",
+    "@types/node": "20.11.0",
     "@typescript-eslint/eslint-plugin": "6.18.1",
-    "@vitest/coverage-v8": "1.1.3",
+    "@vitest/coverage-v8": "1.2.0",
     "eslint": "8.56.0",
     "eslint-plugin-import": "2.29.1",
     "eslint-plugin-jsdoc": "48.0.2",
     "http-server": "14.1.1",
     "typescript": "5.3.3",
-    "vitest": "1.1.3"
+    "vitest": "1.2.0"
   }
 }

src/metadata.js

@@ -23,11 +23,11 @@ export function parquetMetadata(arrayBuffer) {
   // Metadata length is 4 bytes before the last PAR1
   const metadataLengthOffset = view.byteLength - 8
   const metadataLength = view.getUint32(view.byteLength - 8, true)
-  if (metadataLength <= 0 || metadataLength > metadataLengthOffset) {
-    throw new Error('parquet file invalid metadata length')
+  if (metadataLength <= 0) {
+    throw new Error('parquet invalid metadata length')
   }
   if (metadataLength > view.byteLength - 8) {
-    throw new Error('parquet file metadata length exceeds file size')
+    throw new Error('parquet metadata length exceeds buffer size')
   }
 
   const metadataOffset = metadataLengthOffset - metadataLength
@@ -98,5 +98,6 @@ export function parquetMetadata(arrayBuffer) {
     row_groups,
     key_value_metadata,
     created_by,
+    metadata_length: metadataLength,
   }
 }

src/types.d.ts

@@ -15,6 +15,7 @@ export interface FileMetaData {
   row_groups: RowGroup[]
   key_value_metadata?: KeyValue[]
   created_by?: string
+  metadata_length: number
 }
 
 export interface SchemaElement {

test/metadata.test.js

@@ -22,6 +22,8 @@ describe('parquetMetadata', () => {
     // Parquet v1 from DuckDB
     const expectedMetadata = {
       version: 1,
+      created_by: 'DuckDB',
+      metadata_length: 149,
       schema: [
         { repetition_type: 0, name: 'duckdb_schema', num_children: 1 },
         { type: 6, repetition_type: 1, name: 'ADDRTYPE', converted_type: 0 },
@@ -55,7 +57,6 @@ describe('parquetMetadata', () => {
           num_rows: 10,
         },
       ],
-      created_by: 'DuckDB',
     }
 
     const casted = toJson(result)
@@ -69,6 +70,8 @@ describe('parquetMetadata', () => {
     // Parquet v2 from pandas with 2 row groups
     const expectedMetadata = {
       version: 2,
+      created_by: 'parquet-cpp-arrow version 14.0.2',
+      metadata_length: 1602,
       schema: [
         {
           repetition_type: 0,
@@ -153,7 +156,6 @@ describe('parquetMetadata', () => {
           // value: base64
         },
       ],
-      created_by: 'parquet-cpp-arrow version 14.0.2',
     }
 
     const casted = toJson(result)