fix action plugins and long path under Windows (#551)

PyInstaller doesn't support pkgutil.iter_modules out of the box but there is a workaround:
pyinstaller/pyinstaller#1905

FIX: support long paths under Windows 10 v1607 or later, once enabled in registry/GPO (see Windows README for details), closes #236

docs/Windows-README.md

@@ -25,6 +25,8 @@ and copy the four enclosed files to the same directory as *rdiff-backup.exe*.
 
 You will need to follow either method only once.
 
+> **NOTE:** you might want to [enable long paths support in Windows 10 v1607 or later](https://docs.microsoft.com/windows/win32/fileio/maximum-file-path-limitation#enable-long-paths-in-windows-10-version-1607-and-later)
+
 ## Additional Issues
 
 Currently, *rdiff-backup*'s `--include` and `--exclude` options do not support

src/rdiffbackup/actions_mgr.py

@@ -49,7 +49,7 @@ def get_discovered_actions():
     # and we complete/overwrite with modules delivered in the namespace
     discovered_action_plugins.update({
         name: importlib.import_module(name)
-        for finder, name, ispkg
+        for name
         in _iter_namespace(rdiffbackup.actions)
     })
     # then we create the dictionary of {action_name: ActionClass}
@@ -90,7 +90,18 @@ def _iter_namespace(nsp):
     # returned name an absolute name instead of a relative one. This allows
     # import_module to work without having to do additional modification to
     # the name.
-    return pkgutil.iter_modules(nsp.__path__, nsp.__name__ + ".")
+    prefix = nsp.__name__ + "."
+    for pkg in pkgutil.iter_modules(nsp.__path__, prefix):
+        yield pkg[1]  # pkg is (finder, name, ispkg)
+    # special handling when the package is bundled with PyInstaller
+    # See https://github.com/pyinstaller/pyinstaller/issues/1905
+    toc = set()  # table of content
+    for importer in pkgutil.iter_importers(nsp.__name__.partition(".")[0]):
+        if hasattr(importer, 'toc'):
+            toc |= importer.toc
+    for name in toc:
+        if name.startswith(prefix):
+            yield name
 
 
 if __name__ == "__main__":

tools/hook-rdiffbackup.actions_mgr.py

@@ -0,0 +1,2 @@
+from PyInstaller.utils.hooks import collect_submodules
+hiddenimports = collect_submodules('rdiffbackup.actions')

tools/win_build_rdiffbackup.sh

@@ -35,5 +35,6 @@ py_ver_brief=${PYTHON_VERSION%.[0-9]}
 ${PYEXE} setup.py bdist_wheel
 ${PYINST} --onefile --distpath build/${ver_name}-${bits} \
 	--paths=build/lib.win32-${py_ver_brief} \
+	--additional-hooks-dir=tools
 	--console build/scripts-${py_ver_brief}/rdiff-backup \
 	--add-data=src/rdiff_backup.egg-info/PKG-INFO\;rdiff_backup.egg-info

tools/windows/playbook-build-rdiff-backup.yml

@@ -28,8 +28,10 @@
     - name: compile rdiff-backup into an executable using pyinstaller
       win_command: >
         pyinstaller --onefile
-        --paths=build/lib.{{ python_win_bits }}-{{ python_version }} --paths={{ librsync_install_dir }}/lib
+        --paths=build/lib.{{ python_win_bits }}-{{ python_version }}
+        --paths={{ librsync_install_dir }}/lib
         --paths={{ librsync_install_dir }}/bin
+        --additional-hooks-dir=tools
         --console build/scripts-{{ python_version }}/rdiff-backup
         --add-data src/rdiff_backup.egg-info/PKG-INFO;rdiff_backup.egg-info
       environment: