Load .data files from the same base URL as .js

src/pyodide.js

@@ -35,8 +35,10 @@ var languagePluginLoader = new Promise((resolve, reject) => {
   let _loadPackage = (names) => {
     // DFS to find all dependencies of the requested packages
     let packages = window.pyodide._module.packages.dependencies;
+    let loadedPackages = window.pyodide.loadedPackages;
     let queue = [].concat(names || []);
     let toLoad = new Array();
+    window.pyodide._toLoadPackages = toLoad;
     while (queue.length) {
       let package_uri = queue.pop();
 
@@ -87,7 +89,7 @@ var languagePluginLoader = new Promise((resolve, reject) => {
       window.pyodide._module.monitorRunDependencies = (n) => {
         if (n === 0) {
           for (let package in toLoad) {
-            loadedPackages[package] = toLoad[package];
+            window.pyodide.loadedPackages[package] = toLoad[package];
           }
           delete window.pyodide._module.monitorRunDependencies;
           const packageList = Array.from(Object.keys(toLoad)).join(', ');
@@ -195,7 +197,20 @@ var languagePluginLoader = new Promise((resolve, reject) => {
     return {};
   };
 
-  Module.locateFile = (path) => baseURL + path;
+  Module.locateFile = (path) => {
+    if ((window.hasOwnProperty('pyodide')) &&
+        (window.pyodide.hasOwnProperty('_toLoadPackages'))) {
+      // handle packages loaded from custom URLs
+      let package = path.replace(/\.data$/, "");
+      if (package in window.pyodide._toLoadPackages) {
+        let package_uri = window.pyodide._toLoadPackages[package];
+        if (package_uri != 'default channel') {
+          return package_uri.replace(/\.js$/, ".data");
+        };
+      };
+    };
+    return baseURL + path;
+  };
   var postRunPromise = new Promise((resolve, reject) => {
     Module.postRun = () => {
       delete window.Module;
@@ -232,6 +247,7 @@ var languagePluginLoader = new Promise((resolve, reject) => {
       // filesystem to install itself. Once that's complete, it will be replaced
       // by the call to `makePublicAPI` with a more limited public API.
       window.pyodide = pyodide(Module);
+      window.pyodide.loadedPackages = new Array();
       window.pyodide.loadPackage = loadPackage;
     };
     document.head.appendChild(script);

test/conftest.py

@@ -272,6 +272,11 @@ def run_web_server(q, log_filepath):
                      *self.client_address,
                      format_ % args))
 
+        def end_headers(self):
+            # Enable Cross-Origin Resource Sharing (CORS)
+            self.send_header('Access-Control-Allow-Origin', '*')
+            super().end_headers()
+
     Handler.extensions_map['.wasm'] = 'application/wasm'
 
     with socketserver.TCPServer(("", 0), Handler) as httpd:

test/test_package_loading.py

@@ -11,8 +11,8 @@ def test_load_from_url(selenium_standalone, web_server_secondary):
             log_main.open('r') as fh_main:
 
         # skip existing log lines
-        fh_main.read()
+        fh_main.seek(0, 2)
-        fh_secondary.read()
+        fh_secondary.seek(0, 2)
 
         selenium_standalone.load_package(f"http://{url}:{port}/pyparsing.js")
         assert "Invalid package name or URI" not in selenium_standalone.logs
@@ -32,6 +32,16 @@ def test_load_from_url(selenium_standalone, web_server_secondary):
     selenium_standalone.run("import numpy as np")
 
 
+def test_list_loaded_urls(selenium_standalone):
+    selenium = selenium_standalone
+
+    selenium.load_package('pyparsing')
+    assert selenium.run_js(
+            'return Object.keys(pyodide.loadedPackages)') == ['pyparsing']
+    assert selenium.run_js(
+            "return pyodide.loadedPackages['pyparsing']") == "default channel"
+
+
 def test_uri_mismatch(selenium_standalone):
     selenium_standalone.load_package('pyparsing')
     selenium_standalone.load_package('http://some_url/pyparsing.js')