fix(cli-repl): patch WASM wrapper for pac-proxy-agent on s390x MONGOSH-1858 (#2130)

Work around justjake/quickjs-emscripten#123.

Author: addaleax

packages/cli-repl/.depcheckrc

@@ -18,5 +18,7 @@ ignores:
  - ipv6-normalize
  - bindings
  - system-ca
+ # used for monkey-patching our s390x fix in
+ - '@tootallnate/quickjs-emscripten'
 ignore-patterns:
  - .eslintrc.js

packages/cli-repl/src/pac-proxy-s390x-patch.ts

@@ -0,0 +1,53 @@
+import assert from 'assert';
+
+const isBigEndian =
+  new Int32Array(new Uint8Array([1, 0, 0, 0]).buffer)[0] !== 1;
+
+// The pac-proxy-agent module uses a WebAssembly agent under the hood for
+// safely evaluating JS. The interface for this doesn't properly account for
+// little-endian vs. big-endian host platform distinctions.
+
+// Official support for s390x may not be planned: https://github.com/justjake/quickjs-emscripten/issues/123
+
+export let applyPacProxyS390XPatch: () => void;
+if (isBigEndian) {
+  applyPacProxyS390XPatch = () => {
+    // eslint-disable-next-line @typescript-eslint/no-var-requires
+    const {
+      ModuleMemory,
+    } = require('@tootallnate/quickjs-emscripten/dist/memory');
+
+    const { toPointerArray } = ModuleMemory.prototype;
+    {
+      // Consistency check: The version we are currently using is actually broken
+      const HEAPU8 = new Uint8Array(4);
+      toPointerArray.call(
+        new ModuleMemory({
+          _malloc: () => 0,
+          HEAPU8,
+        }),
+        [{ value: 0x01020304 }]
+      );
+      assert.deepStrictEqual([...HEAPU8], [1, 2, 3, 4]); // should be 4, 3, 2, 1
+    }
+
+    ModuleMemory.prototype.toPointerArray = function (
+      handleArray: { value: number }[]
+    ) {
+      return toPointerArray.call(
+        this,
+        handleArray.map(({ value }) => ({
+          value:
+            ((value & 0x000000ff) << 24) |
+            ((value & 0x0000ff00) << 8) |
+            ((value & 0x00ff0000) >> 8) |
+            ((value & 0xff000000) >> 24),
+        }))
+      );
+    };
+  };
+} else {
+  applyPacProxyS390XPatch = () => {
+    // no-op
+  };
+}

packages/cli-repl/src/run.ts

@@ -22,6 +22,7 @@ import { baseBuildInfo, buildInfo } from './build-info';
 import { getStoragePaths, getGlobalConfigPaths } from './config-directory';
 import { getCryptLibraryPaths } from './crypt-library-paths';
 import { getTlsCertificateSelector } from './tls-certificate-selector';
+import { applyPacProxyS390XPatch } from './pac-proxy-s390x-patch';
 import { redactURICredentials } from '@mongosh/history';
 import { generateConnectionInfoFromCliArgs } from '@mongosh/arg-parser';
 import askcharacter from 'askcharacter';
@@ -170,6 +171,8 @@ async function main() {
       process.removeAllListeners('SIGINT');
     }
 
+    applyPacProxyS390XPatch();
+
     // If we are spawned via Windows doubleclick, ask the user for an URI to
     // connect to. Allow an environment variable to override this for testing.
     isSingleConsoleProcess =

packages/e2e-tests/test/e2e-snapshot.spec.ts

@@ -15,7 +15,7 @@ const commonPrefix = (a: string, b: string): string =>
     ? a
     : b && commonPrefix(a, b.slice(0, -1));
 
-describe('e2e startup banners', function () {
+describe('e2e snapshot support', function () {
   skipIfApiStrict();
   afterEach(TestShell.cleanup);
 
@@ -103,14 +103,22 @@ describe('e2e startup banners', function () {
       // console.table(categorized.map(([m, c]) => [m.replace(prefix, ''), c]));
       const verifyAllInCategoryMatch = (
         category: (typeof categorized)[number][1],
-        re: RegExp
+        re: RegExp,
+        negative = false
       ) => {
         for (const [module, cat] of categorized) {
           if (cat === category) {
-            expect(module).to.match(
-              re,
-              `Found unexpected '${module}' in category '${cat}'`
-            );
+            if (negative) {
+              expect(module).not.to.match(
+                re,
+                `Found unexpected '${module}' in category '${cat}'`
+              );
+            } else {
+              expect(module).to.match(
+                re,
+                `Found unexpected '${module}' in category '${cat}'`
+              );
+            }
           }
         }
       };
@@ -138,8 +146,12 @@ describe('e2e startup banners', function () {
       );
       verifyAllInCategoryMatch(
         'nodb-eval',
-        /^node_modules\/(kerberos|mongodb-client-encryption|glibc-version|@mongodb-js\/devtools-proxy-support|@mongodb-js\/socksv5|agent-base|(win|macos)-export-certificate-and-key)\//
+        /^node_modules\/(kerberos|mongodb-client-encryption|glibc-version|@mongodb-js\/devtools-proxy-support|@mongodb-js\/socksv5|agent-base|(win|macos)-export-certificate-and-key|@tootallnate\/quickjs-emscripten)\//
       );
+      if (process.arch !== 's390x') {
+        // quickjs is in the list above but should be exlucded anywhere but on s390x
+        verifyAllInCategoryMatch('nodb-eval', /quickjs-emscripten/, true);
+      }
       verifyAllThatMatchAreInCategory(
         'not-loaded',
         /^node_modules\/(express|openid-client|qs|send|jose|execa|body-parser|@babel\/highlight|@babel\/code-frame)\//