wasm: make qtloader.js use FS.createPreloadedFile when preloading

Currently qtloader.js fetches and copies the files manually. By doing
so we are missing some preproccessing by Emscripten preload plugins.
Use Emscripten API to preload files, so preload plugin for .so can
download, compile and resolve dependencies of imported shared libraries.

This makes looking for dependencies in preload_qml_import.py no longer
needed. Remove redundant code.

Fixes: QTBUG-121817
Change-Id: Idd35f25d5f54123910f813a636407eea23e157cb
Reviewed-by: Piotr Wierciński <piotr.wiercinski@qt.io>

1 files changed, 19 insertions, 23 deletions

diff --git a/src/plugins/platforms/wasm/qtloader.js b/src/plugins/platforms/wasm/qtloader.js
index 89944d6dd9..bbc0ac68ab 100644
--- a/src/plugins/platforms/wasm/qtloader.js
+++ b/src/plugins/platforms/wasm/qtloader.js
@@ -120,14 +120,15 @@ async function qtLoad(config)
             }
         }
     }
-
+    const fetchJsonHelper = async path => (await fetch(path)).json();
+    const filesToPreload = (await Promise.all(config.qt.preload.map(fetchJsonHelper))).flat();
     const qtPreRun = (instance) => {
         // Copy qt.environment to instance.ENV
         throwIfEnvUsedButNotExported(instance, config);
         for (const [name, value] of Object.entries(config.qt.environment ?? {}))
             instance.ENV[name] = value;
 
-        // Copy self.preloadData to MEMFS
+        // Preload files from qt.preload
         const makeDirs = (FS, filePath) => {
             const parts = filePath.split("/");
             let path = "/";
@@ -146,14 +147,25 @@ async function qtLoad(config)
             }
         }
 
+        const extractFilenameAndDir = (path) => {
+            const parts = path.split('/');
+            const filename = parts.pop();
+            const dir = parts.join('/');
+            return {
+                filename: filename,
+                dir: dir
+            };
+        }
+        const preloadFile = (file) => {
+            makeDirs(instance.FS, file.destination);
+            const source = file.source.replace('$QTDIR', config.qt.qtdir);
+            const filenameAndDir = extractFilenameAndDir(file.destination);
+            instance.FS.createPreloadedFile(filenameAndDir.dir, filenameAndDir.filename, source, true, true);
+        }
         const isFsExported = typeof instance.FS === 'object';
         if (!isFsExported)
             throw new Error('FS must be exported if preload is used');
-
-        for ({destination, data} of self.preloadData) {
-            makeDirs(instance.FS, destination);
-            instance.FS.writeFile(destination, new Uint8Array(data));
-        }
+        filesToPreload.forEach(preloadFile);
     }
 
     if (!config.preRun)
@@ -197,22 +209,6 @@ async function qtLoad(config)
         }
     };
 
-    const fetchPreloadFiles = async () => {
-        const fetchJson = async path => (await fetch(path)).json();
-        const fetchArrayBuffer = async path => (await fetch(path)).arrayBuffer();
-        const loadFiles = async (paths) => {
-            const source = paths['source'].replace('$QTDIR', config.qt.qtdir);
-            return {
-                destination: paths['destination'],
-                data: await fetchArrayBuffer(source)
-            };
-        }
-        const fileList = (await Promise.all(config.qt.preload.map(fetchJson))).flat();
-        self.preloadData = (await Promise.all(fileList.map(loadFiles))).flat();
-    }
-
-    await fetchPreloadFiles();
-
     // Call app/emscripten module entry function. It may either come from the emscripten
     // runtime script or be customized as needed.
     let instance;