fix prepend size

Author: crimson-gao

alibabacloud-gateway-sls/util/ts/src/common.ts

@@ -2,11 +2,16 @@ import { Readable } from 'stream';
 
 export async function readableStreamToBuffer(stream: Readable): Promise<Buffer> {
     const chunks: Buffer[] = [];
-    return new Promise((resolve, reject) => {
-        stream.on('data', (chunk: Buffer) => chunks.push(chunk));
-        stream.on('error', reject);
-        stream.on('end', () => {
-            resolve(Buffer.concat(chunks));
-        });
-    });
+    for await (const chunk of stream) {
+        chunks.push(chunk as Buffer);
+    }
+    return Buffer.concat(chunks);
+}
+
+export async function readableStreamWithPrependBuffer(stream: Readable, prependBuffer: Buffer): Promise<Buffer> {
+    const chunks: Buffer[] = [];
+    for await (const chunk of stream) {
+        chunks.push(chunk as Buffer);
+    }
+    return Buffer.concat([prependBuffer, ...chunks]);
 }

alibabacloud-gateway-sls/util/ts/src/compress.ts

@@ -4,7 +4,8 @@ import zlib from 'zlib';
 const supportedCompressor = ['lz4', 'gzip', 'deflate']
 
 export async function lz4Compress(data: Buffer): Promise<Buffer> {
-    return await napiLz4Compress(data);
+    // eliminate 4 bytes prepended size
+    return (await napiLz4Compress(data)).slice(4);
 }
 
 export async function gzipCompress(data: Buffer): Promise<Buffer> {

alibabacloud-gateway-sls/util/ts/src/decompress.ts

@@ -1,18 +1,22 @@
 import { Readable } from 'stream';
-import { readableStreamToBuffer } from './common';
+import { readableStreamToBuffer, readableStreamWithPrependBuffer } from './common';
 import {uncompress as napiLz4Uncompress} from 'lz4-napi';
 import zlib from 'zlib';
-
+import fs from 'fs';
 const supportedDecompressor = ['lz4', 'gzip', 'deflate']
 
 export async function isDecompressorAvailable(compressType: string): Promise<boolean> {
     return supportedDecompressor.includes(compressType);
 }
 
 export async function lz4Decompress(input: Readable, bodyRawSize: number): Promise<Buffer> {
-    const napiOutput = await napiLz4Uncompress(await readableStreamToBuffer(input));
+    // prepend 4 bytes size to the buffer
+    const sizeBuffer = Buffer.alloc(4);
+    sizeBuffer.writeUInt32LE(bodyRawSize, 0);
+    let compressedBuffer = await readableStreamWithPrependBuffer(input, sizeBuffer);
+    const napiOutput = await napiLz4Uncompress(compressedBuffer);
     if (napiOutput.length !== bodyRawSize) {
-        return Buffer.from(napiOutput.slice(0, bodyRawSize));
+        throw new Error(`unexpected uncompressed size: ${napiOutput.length}, expected: ${bodyRawSize}`);
     }
     return napiOutput;
 }