wasm: Generate plugin preloads for dynamic linking at install step

Dynamic linking on WebAssembly involves preloading .so libraries
during startup of application. Normally, those plugin preload
lists are generating manually by user.
Automate this process as part of installation step.

Change-Id: I364ebdb170f9fac53da241c96f601613352972d8
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>

cmake/QtBaseGlobalTargets.cmake

@@ -378,9 +378,17 @@ if(APPLE)
 elseif(WASM)
     configure_file("${CMAKE_CURRENT_SOURCE_DIR}/util/wasm/wasmtestrunner/qt-wasmtestrunner.py"
         "${QT_BUILD_DIR}/${INSTALL_LIBEXECDIR}/qt-wasmtestrunner.py" @ONLY)
+    configure_file("${CMAKE_CURRENT_SOURCE_DIR}/util/wasm/preload/preload_qml_imports.py"
+        "${QT_BUILD_DIR}/${INSTALL_LIBEXECDIR}/preload_qml_imports.py" COPYONLY)
+    configure_file("${CMAKE_CURRENT_SOURCE_DIR}/util/wasm/preload/preload_qt_plugins.py"
+        "${QT_BUILD_DIR}/${INSTALL_LIBEXECDIR}/preload_qt_plugins.py" COPYONLY)
 
     qt_install(PROGRAMS "${QT_BUILD_DIR}/${INSTALL_LIBEXECDIR}/qt-wasmtestrunner.py"
         DESTINATION "${INSTALL_LIBEXECDIR}")
+    qt_install(PROGRAMS "${QT_BUILD_DIR}/${INSTALL_LIBEXECDIR}/preload_qml_imports.py"
+        DESTINATION "${INSTALL_LIBEXECDIR}")
+    qt_install(PROGRAMS "${QT_BUILD_DIR}/${INSTALL_LIBEXECDIR}/preload_qt_plugins.py"
+        DESTINATION "${INSTALL_LIBEXECDIR}")
 endif()
 
 # Install CI support files to libexec.

src/corelib/Qt6WasmMacros.cmake

@@ -91,6 +91,49 @@ function(_qt_internal_wasm_add_target_helpers target)
                         ${_target_directory}/qtloader.js COPYONLY)
                     configure_file("${WASM_BUILD_DIR}/plugins/platforms/qtlogo.svg"
                         ${_target_directory}/qtlogo.svg COPYONLY)
+
+                    if(QT_FEATURE_shared)
+                        configure_file("${WASM_BUILD_DIR}/libexec/preload_qml_imports.py"
+                            ${_target_directory}/preload_qml_imports.py COPYONLY)
+                        configure_file("${WASM_BUILD_DIR}/libexec/preload_qt_plugins.py"
+                            ${_target_directory}/preload_qt_plugins.py COPYONLY)
+                    endif()
+
+                    if(CMAKE_STAGING_PREFIX)
+                        install(FILES
+                            ${_target_directory}/qtloader.js
+                            ${_target_directory}/qtlogo.svg
+                            ${_target_directory}/${_target_output_name}.html
+                            ${_target_directory}/${_target_output_name}.wasm
+                            ${_target_directory}/${_target_output_name}.js
+                                    DESTINATION ${CMAKE_STAGING_PREFIX})
+                        if(QT_FEATURE_thread)
+                            install(FILES
+                                ${_target_directory}/${_target_output_name}.worker.js
+                                    DESTINATION ${CMAKE_STAGING_PREFIX})
+                        endif()
+
+                        if(QT_FEATURE_shared)
+                            find_package(Python3 COMPONENTS Interpreter)
+                            if(Python3_Interpreter_FOUND)
+                                install(FILES
+                                    ${_target_directory}/preload_qml_imports.py
+                                    ${_target_directory}/preload_qt_plugins.py
+                                        DESTINATION ${CMAKE_STAGING_PREFIX})
+                                install(CODE "execute_process(COMMAND ${Python3_EXECUTABLE} \
+                                    ${_target_directory}/preload_qml_imports.py \
+                                    ${CMAKE_CURRENT_SOURCE_DIR} ${QT_HOST_PATH} \
+                                    ${QT6_INSTALL_PREFIX} \
+                                    ${CMAKE_STAGING_PREFIX})")
+                                install(CODE "execute_process(COMMAND ${Python3_EXECUTABLE} \
+                                    ${_target_directory}/preload_qt_plugins.py \
+                                    ${QT6_INSTALL_PREFIX} \
+                                    ${CMAKE_STAGING_PREFIX})")
+                            else()
+                                message(WARNING "Python 3 not found. Generating preload list for dynamic linking is disabled.")
+                            endif()
+                        endif()
+                    endif()
                 endif()
             endif()
         endif()

util/wasm/preload/preload_qml_imports.py

@@ -19,10 +19,6 @@ qt_qml_path = "$QTDIR/qml"
 qt_deploy_qml_path = "/qt/qml"
 
 
-def eprint(*args, **kwargs):
-    print(*args, file=sys.stderr, **kwargs)
-
-
 def preload_file(source, destination):
     preload_files.append({"source": source, "destination": destination})
 
@@ -55,24 +51,23 @@ def extract_preload_files_from_imports(imports):
             )
             preload_file(qmldir_source_path, qmldir_destination_path)
         except Exception as e:
-            eprint(e)
             continue
     return libraries
 
 
 if __name__ == "__main__":
-    if len(sys.argv) != 4:
+    if len(sys.argv) != 5:
-        print("Usage: python preload_qml_imports.py <qml-source-path> <qt-host-path> <qt-wasm-path>")
+        print("Usage: python preload_qml_imports.py <qml-source-path> <qt-host-path> <qt-wasm-path> <output-dir>")
         sys.exit(1)
 
     qml_source_path = sys.argv[1]
     qt_host_path = sys.argv[2]
     qt_wasm_path = sys.argv[3]
+    output_dir = sys.argv[4]
 
     qml_import_path = os.path.join(qt_wasm_path, "qml")
     qmlimportsscanner_path = os.path.join(qt_host_path, "libexec/qmlimportscanner")
 
-    eprint("runing qmlimportsscanner")
     command = [qmlimportsscanner_path, "-rootPath", qml_source_path, "-importPath", qml_import_path]
     result = subprocess.run(command, stdout=subprocess.PIPE)
     imports = json.loads(result.stdout)
@@ -98,4 +93,6 @@ if __name__ == "__main__":
         destination = os.path.join("/", library)
         preload_file(source, destination)
 
-    print(json.dumps(preload_files, indent=2))
+    with open(f"{output_dir}/qt_qml_imports.json", "w") as f:
+        f.write(json.dumps(preload_files, indent=2))
+

util/wasm/preload/preload_qt_plugins.py

@@ -27,11 +27,12 @@ def find_so_files(directory):
 
 
 if __name__ == "__main__":
-    if len(sys.argv) != 2:
+    if len(sys.argv) != 3:
-        print("Usage: python make_qt_symlinks.py <qt-wasm-path>")
+        print("Usage: python preload_qt_plugins.py <qt-wasm-path> <output-dir>")
         sys.exit(1)
 
     qt_wasm_path = sys.argv[1]
+    output_dir = sys.argv[2]
 
     # preload all plugins
     plugins = find_so_files(os.path.join(qt_wasm_path, "plugins"))
@@ -47,8 +48,10 @@ if __name__ == "__main__":
     # and QML imports in /qt/plugins and /qt/qml. The qt.conf file is
     # written to the current directory.
     qtconf = "[Paths]\nPrefix = /qt\n"
-    with open("qt.conf", "w") as f:
+    with open(f"{output_dir}/qt.conf", "w") as f:
         f.write(qtconf)
     preload.append({"source": "qt.conf", "destination": "/qt.conf"})
 
-    print(json.dumps(preload, indent=2))
+    with open(f"{output_dir}/qt_plugins.json", "w") as f:
+        f.write(json.dumps(preload, indent=2))
+