mirror of
https://gitlab.gnome.org/GNOME/glib.git
synced 2024-11-07 09:56:15 +01:00
93 lines
2.7 KiB
Markdown
93 lines
2.7 KiB
Markdown
Title: Dynamic Loading of Modules
|
|
|
|
## Dynamic Loading of Modules
|
|
|
|
These functions provide a portable way to dynamically load object files
|
|
(commonly known as 'plug-ins'). The current implementation supports all
|
|
systems that provide an implementation of `dlopen()` (e.g. Linux/Sun), as
|
|
well as Windows platforms via DLLs.
|
|
|
|
A program which wants to use these functions must be linked to the libraries
|
|
output by the command:
|
|
|
|
pkg-config --libs gmodule-2.0
|
|
|
|
To use them you must first determine whether dynamic loading is supported on
|
|
the platform by calling [`func@GModule.Module.supported`]. If it is, you can
|
|
open a module with [`func@GModule.Module.open`], find the module's symbols
|
|
(e.g. function names) with [`method@GModule.Module.symbol`], and later close
|
|
the module with [`method@GModule.Module.close`].
|
|
[`method@GModule.Module.name`] will return the file name of a currently
|
|
opened module.
|
|
|
|
If any of the above functions fail, the error status can be found with
|
|
[`func@GModule.Module.error`].
|
|
|
|
The `GModule` implementation features reference counting for opened modules,
|
|
and supports hook functions within a module which are called when the module
|
|
is loaded and unloaded (see [callback@GModule.ModuleCheckInit] and
|
|
[callback@GModule.ModuleUnload]).
|
|
|
|
If your module introduces static data to common subsystems in the running
|
|
program, e.g. through calling API like:
|
|
|
|
```c
|
|
static GQuark my_module_quark =
|
|
g_quark_from_static_string ("my-module-stuff");
|
|
```
|
|
|
|
it must ensure that it is never unloaded, by calling
|
|
[`method@GModule.Module.make_resident`].
|
|
|
|
### Calling a function defined in a GModule
|
|
|
|
```c
|
|
// the function signature for 'say_hello'
|
|
typedef void (* SayHelloFunc) (const char *message);
|
|
|
|
gboolean
|
|
just_say_hello (const char *filename, GError **error)
|
|
{
|
|
SayHelloFunc say_hello;
|
|
GModule *module;
|
|
|
|
module = g_module_open (filename, G_MODULE_BIND_LAZY);
|
|
if (module == NULL)
|
|
{
|
|
g_set_error (error, FOO_ERROR, FOO_ERROR_BLAH,
|
|
"%s", g_module_error ());
|
|
return FALSE;
|
|
}
|
|
|
|
if (!g_module_symbol (module, "say_hello", (gpointer *)&say_hello))
|
|
{
|
|
g_set_error (error, SAY_ERROR, SAY_ERROR_OPEN,
|
|
"%s: %s", filename, g_module_error ());
|
|
|
|
if (!g_module_close (module))
|
|
g_warning ("%s: %s", filename, g_module_error ());
|
|
|
|
return FALSE;
|
|
}
|
|
|
|
if (say_hello == NULL)
|
|
{
|
|
g_set_error (error, SAY_ERROR, SAY_ERROR_OPEN,
|
|
"symbol say_hello is NULL");
|
|
|
|
if (!g_module_close (module))
|
|
g_warning ("%s: %s", filename, g_module_error ());
|
|
|
|
return FALSE;
|
|
}
|
|
|
|
// call our function in the module
|
|
say_hello ("Hello world!");
|
|
|
|
if (!g_module_close (module))
|
|
g_warning ("%s: %s", filename, g_module_error ());
|
|
|
|
return TRUE;
|
|
}
|
|
```
|