a8c1d8bbf1
Several parts of kmscon have huge external dependencies. However, we allow them to be disabled during build-time. But this is not enough as it requires distributions to choose which options to use. Therefore, we now allow dynamicly loadable modules that can optionally be installed and kmscon automatically picks them up. Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
72 lines
3.1 KiB
C
72 lines
3.1 KiB
C
/*
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* kmscon - Module handling
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*
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* Copyright (c) 2012-2013 David Herrmann <dh.herrmann@googlemail.com>
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files
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* (the "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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/*
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* Module Handling
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* Several subsystems of kmscon provide a generic interface that is implemented
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* by different backends. The user can choose a backend that is then used.
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* To make out-of-tree development easier and, more importantly, to reduce the
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* direct dependencies to external libraries, this subsystem implements a
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* dynamically-loadable module system.
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*
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* Modules can be loaded and unloaded during runtime. A module basically
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* provides memory-storage for code. As long as any code of a module is still
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* used (that is, registered as callback) we must not unload the module.
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* Therefore, we use reference-counting to allow other subsystems to acquire and
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* release code sections.
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*
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* A module needs to provide "module_init". Everything else is optional.
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* "module_init" is called after the module has been loaded and should
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* initialize the module. "module_exit" is called after the module has been
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* unloaded and the last reference to the module has been dropped. Therefore, it
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* is safe to release all allocated resources in "module_exit".
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*
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* "module_load" is called after "module_init". A module should register its
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* resources here. "module_unload" is called when the module is scheduled for
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* removal. A module should unregister its resources here. However, it must not
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* release the resources as there might still be users of it. Only when
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* "module_exit" is called, kmscon guarantees that there are no more users and
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* the module can release its resources.
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*/
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#ifndef KMSCON_MODULE_H
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#define KMSCON_MODULE_H
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#include <stdlib.h>
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struct kmscon_module;
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int kmscon_module_open(struct kmscon_module **out, const char *file);
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void kmscon_module_ref(struct kmscon_module *module);
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void kmscon_module_unref(struct kmscon_module *module);
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int kmscon_module_load(struct kmscon_module *module);
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void kmscon_module_unload(struct kmscon_module *module);
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void kmscon_load_modules(void);
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void kmscon_unload_modules(void);
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#endif /* KMSCON_MODULE_H */
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