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/*
* 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
/* 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)
#ifdef __APPLE__
#define HA_SECTION(s) __section__("__DATA, i_" # s)
#else
#define HA_SECTION(s) __section__("init_" # s)
#endif
/* 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 __GLOBL1(sym) __asm__(".globl " #sym)
#define __GLOBL(sym) __GLOBL1(sym)
#define __DECLARE_INITCALL(stg, linenum, function, a1, a2, a3) \
__GLOBL(__start_init_##stg ); \
__GLOBL(__stop_init_##stg ); \
static const struct initcall *__initcb_##linenum \
__attribute__((__used__,HA_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_init_##stg); (p) < &(__stop_init_##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.
*/
#ifdef __APPLE__
#define DECLARE_INIT_SECTION(stg) \
extern __attribute__((__weak__)) const struct initcall *__start_init_##stg __asm("section$start$__DATA$i_" # stg); \
extern __attribute__((__weak__)) const struct initcall *__stop_init_##stg __asm("section$end$__DATA$i_" # stg)
#else
#define DECLARE_INIT_SECTION(stg) \
extern __attribute__((__weak__)) const struct initcall *__start_init_##stg; \
extern __attribute__((__weak__)) const struct initcall *__stop_init_##stg
#endif
/* 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:
*/