gplugin/gplugin

Add a desired-state property to GPlugin.Plugin

2021-12-30, Gary Kramlich
76d43734c071
Add a desired-state property to GPlugin.Plugin

This allows us to track what state the user wanted a plugin to be in. The use
case here is, I want to disable a plugin, but the plugin can't be cleanly
unloaded. The plugin returns FALSE from its unload function with an error
stating as such.

For a GPlugin consuming application this creates a dilema where the user can't
actually disable this plugin, because as far as everyone knows, that plugin
should be loaded. With this new property, the consuming application can then
check if the desired state is set to loaded before saving it to a list of
plugins to that should be loaded at the next launch.

Testing Done:
Updated the loader unit tests to make sure that the property is being set properly by `GPluginLoader`.

Reviewed at https://reviews.imfreedom.org/r/1200/
/*
* Copyright (C) 2011-2020 Gary Kramlich <grim@reaperworld.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <https://www.gnu.org/licenses/>.
*/
#include <gmodule.h>
#include <glib/gi18n-lib.h>
#include <gplugin/gplugin-core.h>
#include <gplugin/gplugin-native-loader.h>
#include <gplugin/gplugin-native-plugin.h>
#include <gplugin/gplugin-private.h>
#define GPLUGIN_QUERY_SYMBOL "gplugin_query"
#define GPLUGIN_LOAD_SYMBOL "gplugin_load"
#define GPLUGIN_UNLOAD_SYMBOL "gplugin_unload"
/**
* GPluginNativeLoader:
*
* A #GPluginLoader subclass that is able to load native plugins.
*/
/**
* GPLUGIN_NATIVE_PLUGIN_ABI_VERSION:
*
* The ABI version of the #GPluginNativeLoader. Your plugin should use this
* as the value for #abi_version when call #gplugin_plugin_info_new.
*/
struct _GPluginNativeLoader {
GPluginLoader parent;
};
G_DEFINE_TYPE(GPluginNativeLoader, gplugin_native_loader, GPLUGIN_TYPE_LOADER)
/******************************************************************************
* Helpers
*****************************************************************************/
static gpointer
gplugin_native_loader_lookup_symbol(
GModule *module,
const gchar *name,
GError **error)
{
gpointer symbol = NULL;
g_return_val_if_fail(module != NULL, NULL);
if(!g_module_symbol(module, name, &symbol)) {
g_set_error(
error,
GPLUGIN_DOMAIN,
0,
_("symbol %s was not found"),
name);
return NULL;
}
return symbol;
}
static GModule *
gplugin_native_loader_open(
const gchar *filename,
GModuleFlags flags,
GError **error)
{
GModule *module = NULL;
module = g_module_open(filename, flags);
if(module)
return module;
if(error) {
const gchar *msg = g_module_error();
*error = g_error_new(
GPLUGIN_DOMAIN,
0,
_("Failed to open plugin '%s': %s"),
filename,
(msg) ? msg : _("Unknown error"));
}
return NULL;
}
/******************************************************************************
* GPluginLoaderInterface API
*****************************************************************************/
static GSList *
gplugin_native_loader_supported_extensions(G_GNUC_UNUSED GPluginLoader *l)
{
GSList *exts = g_slist_append(NULL, G_MODULE_SUFFIX);
#if defined(__APPLE__) || defined(__MACH__)
/* G_MODULE_SUFFIX only requests `.so` on not windows, and both .so and
* .dylib are used on macos, so add dylib if we're on macos.
* See: https://gitlab.gnome.org/GNOME/glib/issues/1413
*/
exts = g_slist_append(exts, "dylib");
#endif
return exts;
}
static GPluginPluginInfo *
gplugin_native_loader_open_and_query(
const gchar *filename,
GModule **module,
GModuleFlags flags,
GPluginNativePluginQueryFunc *query,
GError **error)
{
GPluginPluginInfo *info = NULL;
*module = gplugin_native_loader_open(filename, flags, error);
if(*module == NULL) {
return NULL;
} else if(error && *error) {
g_module_close(*module);
*module = NULL;
return NULL;
}
*query = gplugin_native_loader_lookup_symbol(
*module,
GPLUGIN_QUERY_SYMBOL,
error);
if((*query == NULL) || (error && *error)) {
g_module_close(*module);
*module = NULL;
return NULL;
}
info = ((GPluginNativePluginQueryFunc)(*query))(error);
if(error && *error) {
g_module_close(*module);
*module = NULL;
return NULL;
}
return info;
}
static GPluginPlugin *
gplugin_native_loader_query(
GPluginLoader *loader,
const gchar *filename,
GError **error)
{
GPluginPlugin *plugin = NULL;
GPluginPluginInfo *info = NULL;
GPluginNativePluginLoadFunc load = NULL;
GPluginNativePluginQueryFunc query = NULL;
GPluginNativePluginUnloadFunc unload = NULL;
GModule *module = NULL;
info = gplugin_native_loader_open_and_query(
filename,
&module,
G_MODULE_BIND_LOCAL,
&query,
error);
if(!GPLUGIN_IS_PLUGIN_INFO(info)) {
if(error && *error == NULL) {
g_set_error_literal(
error,
GPLUGIN_DOMAIN,
0,
_("the query function did not return a "
"GPluginPluginInfo instance"));
}
return NULL;
}
if(gplugin_plugin_info_get_bind_global(info)) {
g_module_close(module);
g_object_unref(G_OBJECT(info));
info = gplugin_native_loader_open_and_query(
filename,
&module,
0,
&query,
error);
if(!GPLUGIN_IS_PLUGIN_INFO(info)) {
if(error && *error == NULL) {
g_set_error_literal(
error,
GPLUGIN_DOMAIN,
0,
_("the query function did not return a "
"GPluginPluginInfo instance"));
}
return NULL;
}
}
/* now look for the load symbol */
load =
gplugin_native_loader_lookup_symbol(module, GPLUGIN_LOAD_SYMBOL, error);
if(error && *error) {
g_module_close(module);
g_object_unref(G_OBJECT(info));
return NULL;
}
/* now look for the unload symbol */
unload = gplugin_native_loader_lookup_symbol(
module,
GPLUGIN_UNLOAD_SYMBOL,
error);
if(error && *error) {
g_module_close(module);
g_object_unref(G_OBJECT(info));
return NULL;
}
/* now create the actual plugin instance */
/* clang-format off */
plugin = g_object_new(
GPLUGIN_TYPE_NATIVE_PLUGIN,
"module", module,
"info", info,
"load-func", load,
"unload-func", unload,
"loader", loader,
"filename", filename,
NULL);
/* clang-format on */
/* now that the plugin instance owns the info, remove our ref */
g_object_unref(G_OBJECT(info));
if(!GPLUGIN_IS_NATIVE_PLUGIN(plugin)) {
g_module_close(module);
g_set_error_literal(
error,
GPLUGIN_DOMAIN,
0,
_("failed to create plugin instance"));
return NULL;
}
return plugin;
}
static gboolean
gplugin_native_loader_load(
G_GNUC_UNUSED GPluginLoader *loader,
GPluginPlugin *plugin,
GError **error)
{
GPluginNativePluginLoadFunc func;
g_return_val_if_fail(plugin != NULL, FALSE);
g_return_val_if_fail(GPLUGIN_IS_NATIVE_PLUGIN(plugin), FALSE);
/* get and call the function */
g_object_get(G_OBJECT(plugin), "load-func", &func, NULL);
if(!func(plugin, error)) {
if(error && *error == NULL)
g_set_error_literal(error, GPLUGIN_DOMAIN, 0, _("unknown failure"));
return FALSE;
}
return TRUE;
}
static gboolean
gplugin_native_loader_unload(
G_GNUC_UNUSED GPluginLoader *loader,
GPluginPlugin *plugin,
gboolean shutdown,
GError **error)
{
GPluginNativePluginUnloadFunc func;
g_return_val_if_fail(plugin != NULL, FALSE);
g_return_val_if_fail(GPLUGIN_IS_NATIVE_PLUGIN(plugin), FALSE);
/* get the function */
g_object_get(G_OBJECT(plugin), "unload-func", &func, NULL);
/* validate the function */
if(func == NULL) {
gchar *filename = gplugin_plugin_get_filename(plugin);
g_warning(_("unload function for %s is NULL"), filename);
g_free(filename);
return FALSE;
}
/* now call the function */
if(!func(plugin, shutdown, error)) {
if(error && *error == NULL)
g_set_error_literal(error, GPLUGIN_DOMAIN, 0, _("unknown failure"));
return FALSE;
}
return TRUE;
}
static void
gplugin_native_loader_init(G_GNUC_UNUSED GPluginNativeLoader *loader)
{
}
static void
gplugin_native_loader_class_init(GPluginNativeLoaderClass *klass)
{
GPluginLoaderClass *loader_class = GPLUGIN_LOADER_CLASS(klass);
loader_class->supported_extensions =
gplugin_native_loader_supported_extensions;
loader_class->query = gplugin_native_loader_query;
loader_class->load = gplugin_native_loader_load;
loader_class->unload = gplugin_native_loader_unload;
}
/******************************************************************************
* Public API
*****************************************************************************/
/**
* gplugin_native_loader_new:
*
* Create a new instance of the native plugin loader.
*
* Typically you won't need to call this directly as GPlugin will create it
* unless #GPLUGIN_CORE_FLAGS_DISABLE_NATIVE_LOADER is passed to
* gplugin_init().
*
* Returns: (transfer full): The new instance.
*
* Since: 0.34.0
*/
GPluginLoader *
gplugin_native_loader_new(void)
{
/* clang-format off */
return g_object_new(
GPLUGIN_TYPE_NATIVE_LOADER,
"id", "gplugin-native",
NULL);
/* clang-format on */
}