Don't fail at upload time when module modifies sys.path

src/pyodide/internal/snapshot.ts

@@ -13,7 +13,11 @@ import {
   MEMORY_SNAPSHOT_READER,
   REQUIREMENTS,
 } from 'pyodide-internal:metadata';
-import { reportError, simpleRunPython } from 'pyodide-internal:util';
+import {
+  reportError,
+  simpleRunPython,
+  SimpleRunPythonError,
+} from 'pyodide-internal:util';
 import { default as MetadataReader } from 'pyodide-internal:runtime-generated/metadata';
 
 let LOADED_BASELINE_SNAPSHOT: number;
@@ -262,8 +266,22 @@ function memorySnapshotDoImports(Module: Module): string[] {
   const deduplicatedModules = [...new Set(importedModules)];
 
   // Import the modules list so they are included in the snapshot.
-  if (deduplicatedModules.length > 0) {
-    simpleRunPython(Module, 'import ' + deduplicatedModules.join(','));
+  for (const mod of deduplicatedModules) {
+    try {
+      // If the module manipulates sys.path or sys.meta_path, we hopefully won't be able to import
+      // some of the things it imports. If they import a package that attempts to import from js,
+      // then this might leave the package in an unusable state. TODO: finalizeBootstrap before
+      // taking the snapshot.
+      simpleRunPython(Module, `import ${mod}`);
+    } catch (e) {
+      if (!(e instanceof SimpleRunPythonError)) {
+        // This probably means we segfaulted.
+        throw e;
+      }
+      continue;
+    }
+    // Delete the imported module to avoid polluting the namespace
+    simpleRunPython(Module, `del ${mod.split('.', 1)[0]}`);
   }
 
   return deduplicatedModules;

src/pyodide/internal/util.ts

@@ -1,8 +1,34 @@
 export function reportError(e: any): never {
-  e.stack?.split('\n').forEach((s: any) => console.warn(s));
+  if (e instanceof SimpleRunPythonError) {
+    // PyRun_SimpleString will have written a Python traceback to stderr.
+    console.warn('Command failed:', e.pyCode);
+    console.warn('Error was:');
+    for (const line of e.pyTraceback.split('\n')) {
+      console.warn(line);
+    }
+  } else {
+    e.stack?.split('\n').forEach((s: any) => console.warn(s));
+  }
   throw e;
 }
 
+function setErrorName(errClass: any) {
+  Object.defineProperty(errClass.prototype, 'name', {
+    value: errClass.name,
+  });
+}
+
+export class SimpleRunPythonError extends Error {
+  pyCode: string;
+  pyTraceback: string;
+  constructor(pyCode: string, pyTraceback: string) {
+    super('Failed to run Python code: ' + pyTraceback);
+    this.pyCode = pyCode;
+    this.pyTraceback = pyTraceback;
+  }
+}
+setErrorName(SimpleRunPythonError);
+
 /**
  *  Simple as possible runPython function which works with no foreign function
  *  interface. We need to use this rather than the normal easier to use
@@ -36,13 +62,7 @@ export function simpleRunPython(
   // status 0: Ok
   // status -1: Error
   if (status) {
-    // PyRun_SimpleString will have written a Python traceback to stderr.
-    console.warn('Command failed:', code);
-    console.warn('Error was:');
-    for (const line of err.split('\n')) {
-      console.warn(line);
-    }
-    throw new Error('Failed to run Python code: ' + err);
+    throw new SimpleRunPythonError(code, err);
   }
   return err;
 }