From ee62eb82803e700e2cf14c1299bfdcece8623e0a Mon Sep 17 00:00:00 2001
From: Yagiz Nizipli <yagiz@cloudflare.com>
Date: Mon, 26 Aug 2024 19:44:02 -0400
Subject: [PATCH] add zlib codes constants

---
 src/node/internal/internal_zlib.ts            | 33 +++++++++++++++++++
 src/node/zlib.ts                              |  4 ++-
 .../api/node/tests/zlib-nodejs-test.js        | 22 ++++++++++++-
 3 files changed, 57 insertions(+), 2 deletions(-)

diff --git a/src/node/internal/internal_zlib.ts b/src/node/internal/internal_zlib.ts
index 7c2836792ee3..1c3770f56aef 100644
--- a/src/node/internal/internal_zlib.ts
+++ b/src/node/internal/internal_zlib.ts
@@ -11,6 +11,15 @@ import { isArrayBufferView } from 'node-internal:internal_types';
 import { Zlib } from 'node-internal:internal_zlib_base';
 
 const {
+  CONST_Z_OK,
+  CONST_Z_STREAM_END,
+  CONST_Z_NEED_DICT,
+  CONST_Z_ERRNO,
+  CONST_Z_STREAM_ERROR,
+  CONST_Z_DATA_ERROR,
+  CONST_Z_MEM_ERROR,
+  CONST_Z_BUF_ERROR,
+  CONST_Z_VERSION_ERROR,
   CONST_DEFLATE,
   CONST_DEFLATERAW,
   CONST_INFLATE,
@@ -41,6 +50,30 @@ Object.defineProperties(
   )
 );
 
+// Translation table for return codes.
+const rawCodes: Record<string, number | string> = {
+  Z_OK: CONST_Z_OK,
+  Z_STREAM_END: CONST_Z_STREAM_END,
+  Z_NEED_DICT: CONST_Z_NEED_DICT,
+  Z_ERRNO: CONST_Z_ERRNO,
+  Z_STREAM_ERROR: CONST_Z_STREAM_ERROR,
+  Z_DATA_ERROR: CONST_Z_DATA_ERROR,
+  Z_MEM_ERROR: CONST_Z_MEM_ERROR,
+  Z_BUF_ERROR: CONST_Z_BUF_ERROR,
+  Z_VERSION_ERROR: CONST_Z_VERSION_ERROR,
+};
+
+for (const key of Object.keys(rawCodes)) {
+  rawCodes[rawCodes[key] as number] = key;
+}
+
+export const codes = {
+  __proto__: null,
+  enumerable: true,
+  writable: false,
+  value: Object.freeze(rawCodes),
+};
+
 export function crc32(
   data: ArrayBufferView | string,
   value: number = 0
diff --git a/src/node/zlib.ts b/src/node/zlib.ts
index efecda82e4c8..23fea7caaaa6 100644
--- a/src/node/zlib.ts
+++ b/src/node/zlib.ts
@@ -1,5 +1,5 @@
 import * as zlib from 'node-internal:internal_zlib';
-import { crc32, constants } from 'node-internal:internal_zlib';
+import { crc32, constants, codes } from 'node-internal:internal_zlib';
 import { default as compatFlags } from 'workerd:compatibility-flags';
 
 const { nodeJsZlib } = compatFlags;
@@ -31,6 +31,7 @@ const createUnzip = protectMethod(zlib.createUnzip);
 
 export {
   crc32,
+  codes,
   constants,
 
   // Classes
@@ -54,6 +55,7 @@ export {
 
 export default {
   crc32,
+  codes,
   constants,
 
   // Classes
diff --git a/src/workerd/api/node/tests/zlib-nodejs-test.js b/src/workerd/api/node/tests/zlib-nodejs-test.js
index fa17f2587c83..de60a24d5397 100644
--- a/src/workerd/api/node/tests/zlib-nodejs-test.js
+++ b/src/workerd/api/node/tests/zlib-nodejs-test.js
@@ -759,6 +759,26 @@ export const testZlibBytesRead = {
   },
 };
 
+// Tests are taken from:
+// https://github.com/nodejs/node/blob/3a71ccf6c473357e89be61b26739fd9139dce4db/test/parallel/test-zlib-const.js
+export const zlibConst = {
+  test() {
+    strictEqual(zlib.constants.Z_OK, 0, 'Expected Z_OK to be 0');
+    zlib.constants.Z_OK = 1;
+    strictEqual(zlib.constants.Z_OK, 0, 'Z_OK should be immutable');
+    strictEqual(
+      zlib.codes.Z_OK,
+      0,
+      `Expected Z_OK to be 0; got ${zlib.codes.Z_OK}`
+    );
+    zlib.codes.Z_OK = 1;
+    strictEqual(zlib.codes.Z_OK, 0, 'Z_OK should be immutable');
+    zlib.codes = { Z_OK: 1 };
+    strictEqual(zlib.codes.Z_OK, 0, 'Z_OK should be immutable');
+    assert(Object.isFrozen(zlib.codes), 'Expected zlib.codes to be frozen');
+  },
+};
+
 // Node.js tests relevant to zlib
 //
 // - [ ] test-zlib-brotli-16GB.js
@@ -810,7 +830,7 @@ export const testZlibBytesRead = {
 // - [ ] test-zlib-empty-buffer.js
 // - [ ] test-zlib-invalid-arg-value-brotli-compress.js
 // - [ ] test-zlib-random-byte-pipes.js
-// - [ ] test-zlib-const.js
+// - [x] test-zlib-const.js
 // - [x] test-zlib-failed-init.js
 // - [ ] test-zlib-invalid-input.js
 // - [ ] test-zlib-reset-before-write.js