include/haproxy/initcall.h - haproxy - Gitiles

 /*
  * include/haproxy/initcall.h
  *
  * Initcall management.
  *
  * Copyright (C) 2018-2020 Willy Tarreau - w@1wt.eu
  *
  * Permission is hereby granted, free of charge, to any person obtaining
  * a copy of this software and associated documentation files (the
  * "Software"), to deal in the Software without restriction, including
  * without limitation the rights to use, copy, modify, merge, publish,
  * distribute, sublicense, and/or sell copies of the Software, and to
  * permit persons to whom the Software is furnished to do so, subject to
  * the following conditions:
  *
  * The above copyright notice and this permission notice shall be
  * included in all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  * OTHER DEALINGS IN THE SOFTWARE.
  */

 #ifndef _HAPROXY_INITCALL_H
 #define _HAPROXY_INITCALL_H

 #include <haproxy/compiler.h>

 /* List of known init stages. If others are added, please declare their
  * section at the end of the file below.
  */

 /* The principle of the initcalls is to create optional sections in the target
  * program which are made of arrays of structures containing a function pointer
  * and 3 argument pointers. Then at boot time, these sections are scanned in a
  * well defined order to call in turn each of these functions with their
  * arguments. This allows to declare register callbacks in C files without
  * having to export lots of things nor to cross-reference functions. There are
  * several initialization stages defined so that certain guarantees are offered
  * (for example list heads might or might not be initialized, pools might or
  * might not have been created yet).
  *
  * On some very old platforms there is no convenient way to retrieve the start
  * or stop pointer for these sections so there is no reliable way to enumerate
  * the callbacks. When this is the case, as detected when USE_OBSOLETE_LINKER
  * is set, instead of using sections we exclusively use constructors whose name
  * is based on the current line number in the file to guarantee uniqueness.
  * When called, these constructors then add their callback to their respective
  * list. It works as well but slightly inflates the executable's size since
  * code has to be emitted just to register each of these callbacks.
  */

 /*
  * Please keep those names short enough, they are used to generate section
  * names, Mac OS X accepts section names up to 16 characters, and we prefix
  * them with i_, so stage name can't be more than 14 characters.
  */
 enum init_stage {
 	STG_PREPARE = 0,      // preset variables, tables, list heads
 	STG_LOCK,             // pre-initialize locks
 	STG_ALLOC,            // allocate required structures
 	STG_POOL,             // create pools
 	STG_REGISTER,         // register static lists (keywords etc)
 	STG_INIT,             // subsystems normal initialization
 	STG_SIZE              // size of the stages array, must be last
 };

 /* This is the descriptor for an initcall */
 struct initcall {
 	void (*const fct)(void *arg1, void *arg2, void *arg3);
 	void *arg1;
 	void *arg2;
 	void *arg3;
 #if defined(USE_OBSOLETE_LINKER)
 	void *next;
 #endif
 };


 #if !defined(USE_OBSOLETE_LINKER)

 #define HA_INIT_SECTION(s)  HA_SECTION("i_" # s)

 /* Declare a static variable in the init section dedicated to stage <stg>,
  * with an element referencing function <function> and arguments <a1..a3>.
  * <linenum> is needed to deduplicate entries created from a same file. The
  * trick with (stg<STG_SIZE) consists in verifying that stg if a valid enum
  * value from the initcall set, and to emit a warning or error if it is not.
  * The function's type is cast so that it is technically possible to call a
  * function taking other argument types, provided they are all the same size
  * as a pointer (args are cast to (void*)). Do not use this macro directly,
  * use INITCALL{0..3}() instead.
  */
 #define __DECLARE_INITCALL(stg, linenum, function, a1, a2, a3)     \
         HA_GLOBL(__start_i_##stg );                                \
         HA_GLOBL(__stop_i_##stg );                                 \
 	static const struct initcall *__initcb_##linenum           \
 	    __attribute__((__used__)) HA_INIT_SECTION(stg) =	   \
 	        (stg < STG_SIZE) ? &(const struct initcall) {      \
 		.fct = (void (*)(void *,void *,void *))function,   \
 		.arg1 = (void *)(a1),                              \
 		.arg2 = (void *)(a2),                              \
 		.arg3 = (void *)(a3),                              \
 	} : NULL


 #else // USE_OBSOLETE_LINKER

 /* Declare a static constructor function to register a static descriptor for
  * stage <stg>, with an element referencing function <function> and arguments
  * <a1..a3>. <linenum> is needed to deduplicate entries created from a same
  * file. The trick with (stg<STG_SIZE) consists in verifying that stg if a
  * valid enum value from the initcall set, and to emit a warning or error if
  * it is not.
  * The function's type is cast so that it is technically possible to call a
  * function taking other argument types, provided they are all the same size
  * as a pointer (args are cast to (void*)). Do not use this macro directly,
  * use INITCALL{0..3}() instead.
  */
 #define __DECLARE_INITCALL(stg, linenum, function, a1, a2, a3)     \
 __attribute__((constructor)) static void __initcb_##linenum()      \
 {                                                                  \
 	static struct initcall entry = {                           \
 		.fct  = (void (*)(void *,void *,void *))function,  \
 		.arg1 = (void *)(a1),                              \
 		.arg2 = (void *)(a2),                              \
 		.arg3 = (void *)(a3),                              \
 	};                                                         \
 	if (stg < STG_SIZE) {                                      \
 		entry.next = __initstg[stg];                       \
 		__initstg[stg] = &entry;                           \
 	};                                                         \
 }

 #endif // USE_OBSOLETE_LINKER

 /* This is used to resolve <linenum> to an integer before calling
  * __DECLARE_INITCALL(). Do not use this macro directly, use INITCALL{0..3}()
  * instead.
  */
 #define _DECLARE_INITCALL(...) \
 	__DECLARE_INITCALL(__VA_ARGS__)

 /* This requires that function <function> is called with pointer argument
  * <argument> during init stage <stage> which must be one of init_stage.
  */
 #define INITCALL0(stage, function)                                     \
 	_DECLARE_INITCALL(stage, __LINE__, function, 0, 0, 0)

 /* This requires that function <function> is called with pointer argument
  * <argument> during init stage <stage> which must be one of init_stage.
  */
 #define INITCALL1(stage, function, arg1)                               \
 	_DECLARE_INITCALL(stage, __LINE__, function, arg1, 0, 0)

 /* This requires that function <function> is called with pointer arguments
  * <arg1..2> during init stage <stage> which must be one of init_stage.
  */
 #define INITCALL2(stage, function, arg1, arg2)                         \
 	_DECLARE_INITCALL(stage, __LINE__, function, arg1, arg2, 0)

 /* This requires that function <function> is called with pointer arguments
  * <arg1..3> during init stage <stage> which must be one of init_stage.
  */
 #define INITCALL3(stage, function, arg1, arg2, arg3)                   \
 	_DECLARE_INITCALL(stage, __LINE__, function, arg1, arg2, arg3)

 #if !defined(USE_OBSOLETE_LINKER)
 /* Iterate pointer p (of type initcall**) over all registered calls at
  * stage <stg>.
  */
 #define FOREACH_INITCALL(p,stg)                                               \
 	for ((p) = &(__start_i_##stg); (p) < &(__stop_i_##stg); (p)++)

 #else // USE_OBSOLETE_LINKER

 #define FOREACH_INITCALL(p,stg)                                               \
 	for ((p) = __initstg[stg]; (p); (p) = (p)->next)
 #endif // USE_OBSOLETE_LINKER


 #if !defined(USE_OBSOLETE_LINKER)
 /* Declare a section for stage <stg>. The start and stop pointers are set by
  * the linker itself, which is why they're declared extern here. The weak
  * attribute is used so that we declare them ourselves if the section is
  * empty. The corresponding sections must contain exclusively pointers to
  * make sure each location may safely be visited by incrementing a pointer.
  */
 #define DECLARE_INIT_SECTION(stg)                                                   \
 	extern __attribute__((__weak__)) const struct initcall *__start_i_##stg HA_SECTION_START("i_" # stg); \
 	extern __attribute__((__weak__)) const struct initcall *__stop_i_##stg  HA_SECTION_STOP("i_" # stg)

 /* Declare all initcall sections here */
 DECLARE_INIT_SECTION(STG_PREPARE);
 DECLARE_INIT_SECTION(STG_LOCK);
 DECLARE_INIT_SECTION(STG_ALLOC);
 DECLARE_INIT_SECTION(STG_POOL);
 DECLARE_INIT_SECTION(STG_REGISTER);
 DECLARE_INIT_SECTION(STG_INIT);

 // for use in the main haproxy.c file
 #define DECLARE_INIT_STAGES asm("")

 /* not needed anymore */
 #undef DECLARE_INIT_SECTION

 #else // USE_OBSOLETE_LINKER

 extern struct initcall *__initstg[STG_SIZE];

 // for use in the main haproxy.c file
 #define DECLARE_INIT_STAGES struct initcall *__initstg[STG_SIZE]

 #endif // USE_OBSOLETE_LINKER

 #if !defined(USE_OBSOLETE_LINKER)
 /* Run the initcalls for stage <stg>. The test on <stg> is only there to
  * ensure it is a valid initcall stage.
  */
 #define RUN_INITCALLS(stg)                                                     \
 	do {                                                                   \
 		const struct initcall **ptr;                                   \
 		if (stg >= STG_SIZE)                                           \
 			break;                                                 \
 		FOREACH_INITCALL(ptr, stg)                                     \
 			(*ptr)->fct((*ptr)->arg1, (*ptr)->arg2, (*ptr)->arg3); \
 	} while (0)

 #else // USE_OBSOLETE_LINKER

 /* Run the initcalls for stage <stg>. The test on <stg> is only there to
  * ensure it is a valid initcall stage.
  */
 #define RUN_INITCALLS(stg)                                                     \
 	do {                                                                   \
 		const struct initcall *ptr;                                    \
 		if (stg >= STG_SIZE)                                           \
 			break;                                                 \
 		FOREACH_INITCALL(ptr, stg)                                     \
 			(ptr)->fct((ptr)->arg1, (ptr)->arg2, (ptr)->arg3);     \
 	} while (0)

 #endif // USE_OBSOLETE_LINKER

 #endif /* _HAPROXY_INITCALL_H */

 /*
  * Local variables:
  *  c-indent-level: 8
  *  c-basic-offset: 8
  * End:
  */
	/*
	* include/haproxy/initcall.h
	*
	* Initcall management.
	*
	* Copyright (C) 2018-2020 Willy Tarreau - w@1wt.eu
	*
	* Permission is hereby granted, free of charge, to any person obtaining
	* a copy of this software and associated documentation files (the
	* "Software"), to deal in the Software without restriction, including
	* without limitation the rights to use, copy, modify, merge, publish,
	* distribute, sublicense, and/or sell copies of the Software, and to
	* permit persons to whom the Software is furnished to do so, subject to
	* the following conditions:
	*
	* The above copyright notice and this permission notice shall be
	* included in all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
	* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
	* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
	* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
	* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
	* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
	* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
	* OTHER DEALINGS IN THE SOFTWARE.
	*/

	#ifndef _HAPROXY_INITCALL_H
	#define _HAPROXY_INITCALL_H

	#include <haproxy/compiler.h>

	/* List of known init stages. If others are added, please declare their
	* section at the end of the file below.
	*/

	/* The principle of the initcalls is to create optional sections in the target
	* program which are made of arrays of structures containing a function pointer
	* and 3 argument pointers. Then at boot time, these sections are scanned in a
	* well defined order to call in turn each of these functions with their
	* arguments. This allows to declare register callbacks in C files without
	* having to export lots of things nor to cross-reference functions. There are
	* several initialization stages defined so that certain guarantees are offered
	* (for example list heads might or might not be initialized, pools might or
	* might not have been created yet).
	*
	* On some very old platforms there is no convenient way to retrieve the start
	* or stop pointer for these sections so there is no reliable way to enumerate
	* the callbacks. When this is the case, as detected when USE_OBSOLETE_LINKER
	* is set, instead of using sections we exclusively use constructors whose name
	* is based on the current line number in the file to guarantee uniqueness.
	* When called, these constructors then add their callback to their respective
	* list. It works as well but slightly inflates the executable's size since
	* code has to be emitted just to register each of these callbacks.
	*/

	/*
	* Please keep those names short enough, they are used to generate section
	* names, Mac OS X accepts section names up to 16 characters, and we prefix
	* them with i_, so stage name can't be more than 14 characters.
	*/
	enum init_stage {
	STG_PREPARE = 0, // preset variables, tables, list heads
	STG_LOCK, // pre-initialize locks
	STG_ALLOC, // allocate required structures
	STG_POOL, // create pools
	STG_REGISTER, // register static lists (keywords etc)
	STG_INIT, // subsystems normal initialization
	STG_SIZE // size of the stages array, must be last
	};

	/* This is the descriptor for an initcall */
	struct initcall {
	void (const fct)(void arg1, void arg2, void arg3);
	void *arg1;
	void *arg2;
	void *arg3;
	#if defined(USE_OBSOLETE_LINKER)
	void *next;
	#endif
	};


	#if !defined(USE_OBSOLETE_LINKER)

	#define HA_INIT_SECTION(s) HA_SECTION("i_" # s)

	/* Declare a static variable in the init section dedicated to stage <stg>,
	* with an element referencing function <function> and arguments <a1..a3>.
	* <linenum> is needed to deduplicate entries created from a same file. The
	* trick with (stg<STG_SIZE) consists in verifying that stg if a valid enum
	* value from the initcall set, and to emit a warning or error if it is not.
	* The function's type is cast so that it is technically possible to call a
	* function taking other argument types, provided they are all the same size
	* as a pointer (args are cast to (void*)). Do not use this macro directly,
	* use INITCALL{0..3}() instead.
	*/
	#define __DECLARE_INITCALL(stg, linenum, function, a1, a2, a3) \
	HA_GLOBL(__start_i_##stg ); \
	HA_GLOBL(__stop_i_##stg ); \
	static const struct initcall *__initcb_##linenum \
	__attribute__((__used__)) HA_INIT_SECTION(stg) = \
	(stg < STG_SIZE) ? &(const struct initcall) { \
	.fct = (void ()(void ,void ,void ))function, \
	.arg1 = (void *)(a1), \
	.arg2 = (void *)(a2), \
	.arg3 = (void *)(a3), \
	} : NULL


	#else // USE_OBSOLETE_LINKER

	/* Declare a static constructor function to register a static descriptor for
	* stage <stg>, with an element referencing function <function> and arguments
	* <a1..a3>. <linenum> is needed to deduplicate entries created from a same
	* file. The trick with (stg<STG_SIZE) consists in verifying that stg if a
	* valid enum value from the initcall set, and to emit a warning or error if
	* it is not.
	* The function's type is cast so that it is technically possible to call a
	* function taking other argument types, provided they are all the same size
	* as a pointer (args are cast to (void*)). Do not use this macro directly,
	* use INITCALL{0..3}() instead.
	*/
	#define __DECLARE_INITCALL(stg, linenum, function, a1, a2, a3) \
	__attribute__((constructor)) static void __initcb_##linenum() \
	{ \
	static struct initcall entry = { \
	.fct = (void ()(void ,void ,void ))function, \
	.arg1 = (void *)(a1), \
	.arg2 = (void *)(a2), \
	.arg3 = (void *)(a3), \
	}; \
	if (stg < STG_SIZE) { \
	entry.next = __initstg[stg]; \
	__initstg[stg] = &entry; \
	}; \
	}

	#endif // USE_OBSOLETE_LINKER

	/* This is used to resolve <linenum> to an integer before calling
	* __DECLARE_INITCALL(). Do not use this macro directly, use INITCALL{0..3}()
	* instead.
	*/
	#define _DECLARE_INITCALL(...) \
	__DECLARE_INITCALL(__VA_ARGS__)

	/* This requires that function <function> is called with pointer argument
	* <argument> during init stage <stage> which must be one of init_stage.
	*/
	#define INITCALL0(stage, function) \
	_DECLARE_INITCALL(stage, __LINE__, function, 0, 0, 0)

	/* This requires that function <function> is called with pointer argument
	* <argument> during init stage <stage> which must be one of init_stage.
	*/
	#define INITCALL1(stage, function, arg1) \
	_DECLARE_INITCALL(stage, __LINE__, function, arg1, 0, 0)

	/* This requires that function <function> is called with pointer arguments
	* <arg1..2> during init stage <stage> which must be one of init_stage.
	*/
	#define INITCALL2(stage, function, arg1, arg2) \
	_DECLARE_INITCALL(stage, __LINE__, function, arg1, arg2, 0)

	/* This requires that function <function> is called with pointer arguments
	* <arg1..3> during init stage <stage> which must be one of init_stage.
	*/
	#define INITCALL3(stage, function, arg1, arg2, arg3) \
	_DECLARE_INITCALL(stage, __LINE__, function, arg1, arg2, arg3)

	#if !defined(USE_OBSOLETE_LINKER)
	/* Iterate pointer p (of type initcall**) over all registered calls at
	* stage <stg>.
	*/
	#define FOREACH_INITCALL(p,stg) \
	for ((p) = &(__start_i_##stg); (p) < &(__stop_i_##stg); (p)++)

	#else // USE_OBSOLETE_LINKER

	#define FOREACH_INITCALL(p,stg) \
	for ((p) = __initstg[stg]; (p); (p) = (p)->next)
	#endif // USE_OBSOLETE_LINKER


	#if !defined(USE_OBSOLETE_LINKER)
	/* Declare a section for stage <stg>. The start and stop pointers are set by
	* the linker itself, which is why they're declared extern here. The weak
	* attribute is used so that we declare them ourselves if the section is
	* empty. The corresponding sections must contain exclusively pointers to
	* make sure each location may safely be visited by incrementing a pointer.
	*/
	#define DECLARE_INIT_SECTION(stg) \
	extern __attribute__((__weak__)) const struct initcall *__start_i_##stg HA_SECTION_START("i_" # stg); \
	extern __attribute__((__weak__)) const struct initcall *__stop_i_##stg HA_SECTION_STOP("i_" # stg)

	/* Declare all initcall sections here */
	DECLARE_INIT_SECTION(STG_PREPARE);
	DECLARE_INIT_SECTION(STG_LOCK);
	DECLARE_INIT_SECTION(STG_ALLOC);
	DECLARE_INIT_SECTION(STG_POOL);
	DECLARE_INIT_SECTION(STG_REGISTER);
	DECLARE_INIT_SECTION(STG_INIT);

	// for use in the main haproxy.c file
	#define DECLARE_INIT_STAGES asm("")

	/* not needed anymore */
	#undef DECLARE_INIT_SECTION

	#else // USE_OBSOLETE_LINKER

	extern struct initcall *__initstg[STG_SIZE];

	// for use in the main haproxy.c file
	#define DECLARE_INIT_STAGES struct initcall *__initstg[STG_SIZE]

	#endif // USE_OBSOLETE_LINKER

	#if !defined(USE_OBSOLETE_LINKER)
	/* Run the initcalls for stage <stg>. The test on <stg> is only there to
	* ensure it is a valid initcall stage.
	*/
	#define RUN_INITCALLS(stg) \
	do { \
	const struct initcall **ptr; \
	if (stg >= STG_SIZE) \
	break; \
	FOREACH_INITCALL(ptr, stg) \
	(ptr)->fct((ptr)->arg1, (ptr)->arg2, (ptr)->arg3); \
	} while (0)

	#else // USE_OBSOLETE_LINKER

	/* Run the initcalls for stage <stg>. The test on <stg> is only there to
	* ensure it is a valid initcall stage.
	*/
	#define RUN_INITCALLS(stg) \
	do { \
	const struct initcall *ptr; \
	if (stg >= STG_SIZE) \
	break; \
	FOREACH_INITCALL(ptr, stg) \
	(ptr)->fct((ptr)->arg1, (ptr)->arg2, (ptr)->arg3); \
	} while (0)

	#endif // USE_OBSOLETE_LINKER

	#endif /* _HAPROXY_INITCALL_H */

	/*
	* Local variables:
	* c-indent-level: 8
	* c-basic-offset: 8
	* End:
	*/