SDL_dynapi.c
Go to the documentation of this file.
/*
Simple DirectMedia Layer
Copyright (C) 1997-2018 Sam Lantinga <slouken@libsdl.org>
This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.
Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not
claim that you wrote the original software. If you use this software
in a product, an acknowledgment in the product documentation would be
appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.
*/
#include "SDL_config.h"
#include "SDL_dynapi.h"
#if SDL_DYNAMIC_API
#if defined(__OS2__)
#define INCL_DOS
#define INCL_DOSERRORS
#include <dos.h>
#endif
#include "SDL.h"
/* These headers have system specific definitions, so aren't included above */
#include "SDL_syswm.h"
#include "SDL_vulkan.h"
/* This is the version of the dynamic API. This doesn't match the SDL version
and should not change until there's been a major revamp in API/ABI.
So 2.0.5 adds functions over 2.0.4? This number doesn't change;
the sizeof (jump_table) changes instead. But 2.1.0 changes how a function
works in an incompatible way or removes a function? This number changes,
since sizeof (jump_table) isn't sufficient anymore. It's likely
we'll forget to bump every time we add a function, so this is the
failsafe switch for major API change decisions. Respect it and use it
sparingly. */
#define SDL_DYNAPI_VERSION 1
static void SDL_InitDynamicAPI(void);
/* BE CAREFUL CALLING ANY SDL CODE IN HERE, IT WILL BLOW UP.
Even self-contained stuff might call SDL_Error and break everything. */
/* behold, the macro salsa! */
/* !!! FIXME: ...disabled...until we write it. :) */
#define DISABLE_JUMP_MAGIC 1
#if DISABLE_JUMP_MAGIC
/* Can't use the macro for varargs nonsense. This is atrocious. */
#define SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, logname, prio) \
_static void SDLCALL SDL_Log##logname##name(int category, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
va_list ap; initcall; va_start(ap, fmt); \
jump_table.SDL_LogMessageV(category, SDL_LOG_PRIORITY_##prio, fmt, ap); \
va_end(ap); \
}
#define SDL_DYNAPI_VARARGS(_static, name, initcall) \
_static int SDLCALL SDL_SetError##name(SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
char buf[512]; /* !!! FIXME: dynamic allocation */ \
va_list ap; initcall; va_start(ap, fmt); \
jump_table.SDL_vsnprintf(buf, sizeof (buf), fmt, ap); \
va_end(ap); \
return jump_table.SDL_SetError("%s", buf); \
} \
_static int SDLCALL SDL_sscanf##name(const char *buf, SDL_SCANF_FORMAT_STRING const char *fmt, ...) { \
int retval; va_list ap; initcall; va_start(ap, fmt); \
retval = jump_table.SDL_vsscanf(buf, fmt, ap); \
va_end(ap); \
return retval; \
} \
_static int SDLCALL SDL_snprintf##name(SDL_OUT_Z_CAP(maxlen) char *buf, size_t maxlen, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
int retval; va_list ap; initcall; va_start(ap, fmt); \
retval = jump_table.SDL_vsnprintf(buf, maxlen, fmt, ap); \
va_end(ap); \
return retval; \
} \
_static void SDLCALL SDL_Log##name(SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
va_list ap; initcall; va_start(ap, fmt); \
jump_table.SDL_LogMessageV(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO, fmt, ap); \
va_end(ap); \
} \
_static void SDLCALL SDL_LogMessage##name(int category, SDL_LogPriority priority, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
va_list ap; initcall; va_start(ap, fmt); \
jump_table.SDL_LogMessageV(category, priority, fmt, ap); \
va_end(ap); \
} \
SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Verbose, VERBOSE) \
SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Debug, DEBUG) \
SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Info, INFO) \
SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Warn, WARN) \
SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Error, ERROR) \
SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Critical, CRITICAL)
#endif
/* Typedefs for function pointers for jump table, and predeclare funcs */
/* The DEFAULT funcs will init jump table and then call real function. */
/* The REAL funcs are the actual functions, name-mangled to not clash. */
#define SDL_DYNAPI_PROC(rc,fn,params,args,ret) \
typedef rc (SDLCALL *SDL_DYNAPIFN_##fn) params; \
static rc SDLCALL fn##_DEFAULT params; \
extern rc SDLCALL fn##_REAL params;
#include "SDL_dynapi_procs.h"
#undef SDL_DYNAPI_PROC
/* The jump table! */
typedef struct {
#define SDL_DYNAPI_PROC(rc,fn,params,args,ret) SDL_DYNAPIFN_##fn fn;
#include "SDL_dynapi_procs.h"
#undef SDL_DYNAPI_PROC
} SDL_DYNAPI_jump_table;
/* Predeclare the default functions for initializing the jump table. */
#define SDL_DYNAPI_PROC(rc,fn,params,args,ret) static rc SDLCALL fn##_DEFAULT params;
#include "SDL_dynapi_procs.h"
#undef SDL_DYNAPI_PROC
/* The actual jump table. */
static SDL_DYNAPI_jump_table jump_table = {
#define SDL_DYNAPI_PROC(rc,fn,params,args,ret) fn##_DEFAULT,
#include "SDL_dynapi_procs.h"
#undef SDL_DYNAPI_PROC
};
/* Default functions init the function table then call right thing. */
#if DISABLE_JUMP_MAGIC
#define SDL_DYNAPI_PROC(rc,fn,params,args,ret) \
static rc SDLCALL fn##_DEFAULT params { \
SDL_InitDynamicAPI(); \
ret jump_table.fn args; \
}
#define SDL_DYNAPI_PROC_NO_VARARGS 1
#include "SDL_dynapi_procs.h"
#undef SDL_DYNAPI_PROC
#undef SDL_DYNAPI_PROC_NO_VARARGS
SDL_DYNAPI_VARARGS(static, _DEFAULT, SDL_InitDynamicAPI())
#else
/* !!! FIXME: need the jump magic. */
#error Write me.
#endif
/* Public API functions to jump into the jump table. */
#if DISABLE_JUMP_MAGIC
#define SDL_DYNAPI_PROC(rc,fn,params,args,ret) \
rc SDLCALL fn params { ret jump_table.fn args; }
#define SDL_DYNAPI_PROC_NO_VARARGS 1
#include "SDL_dynapi_procs.h"
#undef SDL_DYNAPI_PROC
#undef SDL_DYNAPI_PROC_NO_VARARGS
SDL_DYNAPI_VARARGS(,,)
#else
/* !!! FIXME: need the jump magic. */
#error Write me.
#endif
/* Here's the exported entry point that fills in the jump table. */
/* Use specific types when an "int" might suffice to keep this sane. */
typedef Sint32 (SDLCALL *SDL_DYNAPI_ENTRYFN)(Uint32 apiver, void *table, Uint32 tablesize);
extern DECLSPEC Sint32 SDLCALL SDL_DYNAPI_entry(Uint32, void *, Uint32);
Sint32
SDL_DYNAPI_entry(Uint32 apiver, void *table, Uint32 tablesize)
{
SDL_DYNAPI_jump_table *output_jump_table = (SDL_DYNAPI_jump_table *) table;
if (apiver != SDL_DYNAPI_VERSION) {
/* !!! FIXME: can maybe handle older versions? */
return -1; /* not compatible. */
} else if (tablesize > sizeof (jump_table)) {
return -1; /* newer version of SDL with functions we can't provide. */
}
/* Init our jump table first. */
#define SDL_DYNAPI_PROC(rc,fn,params,args,ret) jump_table.fn = fn##_REAL;
#include "SDL_dynapi_procs.h"
#undef SDL_DYNAPI_PROC
/* Then the external table... */
if (output_jump_table != &jump_table) {
jump_table.SDL_memcpy(output_jump_table, &jump_table, tablesize);
}
/* Safe to call SDL functions now; jump table is initialized! */
return 0; /* success! */
}
/* Obviously we can't use SDL_LoadObject() to load SDL. :) */
/* Also obviously, we never close the loaded library. */
#if defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__)
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN 1
#endif
#include <windows.h>
static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym)
{
HANDLE lib = LoadLibraryA(fname);
void *retval = NULL;
if (lib) {
retval = GetProcAddress(lib, sym);
if (retval == NULL) {
FreeLibrary(lib);
}
}
return retval;
}
#elif defined(unix) || defined(__unix__) || defined(__APPLE__) || defined(__HAIKU__) || defined(__QNX__)
#include <dlfcn.h>
static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym)
{
void *lib = dlopen(fname, RTLD_NOW | RTLD_LOCAL);
void *retval = NULL;
if (lib != NULL) {
retval = dlsym(lib, sym);
if (retval == NULL) {
dlclose(lib);
}
}
return retval;
}
#elif defined(__OS2__)
static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym)
{
HMODULE hmodule;
PFN retval = NULL;
char error[256];
if (DosLoadModule(&error, sizeof(error), fname, &hmodule) == NO_ERROR) {
if (DosQueryProcAddr(hmodule, 0, sym, &retval) != NO_ERROR) {
DosFreeModule(hmodule);
}
}
return (void *) retval;
}
#else
#error Please define your platform.
#endif
static void
SDL_InitDynamicAPILocked(void)
{
const char *libname = SDL_getenv_REAL("SDL_DYNAMIC_API");
SDL_DYNAPI_ENTRYFN entry = SDL_DYNAPI_entry; /* funcs from here by default. */
if (libname) {
entry = (SDL_DYNAPI_ENTRYFN) get_sdlapi_entry(libname, "SDL_DYNAPI_entry");
if (!entry) {
/* !!! FIXME: fail to startup here instead? */
/* !!! FIXME: definitely warn user. */
/* Just fill in the function pointers from this library. */
entry = SDL_DYNAPI_entry;
}
}
if (entry(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table)) < 0) {
/* !!! FIXME: fail to startup here instead? */
/* !!! FIXME: definitely warn user. */
/* Just fill in the function pointers from this library. */
if (entry != SDL_DYNAPI_entry) {
if (!SDL_DYNAPI_entry(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table))) {
/* !!! FIXME: now we're screwed. Should definitely abort now. */
}
}
}
/* we intentionally never close the newly-loaded lib, of course. */
}
static void
SDL_InitDynamicAPI(void)
{
/* So the theory is that every function in the jump table defaults to
* calling this function, and then replaces itself with a version that
* doesn't call this function anymore. But it's possible that, in an
* extreme corner case, you can have a second thread hit this function
* while the jump table is being initialized by the first.
* In this case, a spinlock is really painful compared to what spinlocks
* _should_ be used for, but this would only happen once, and should be
* insanely rare, as you would have to spin a thread outside of SDL (as
* SDL_CreateThread() would also call this function before building the
* new thread).
*/
static SDL_bool already_initialized = SDL_FALSE;
/* SDL_AtomicLock calls SDL mutex functions to emulate if
SDL_ATOMIC_DISABLED, which we can't do here, so in such a
configuration, you're on your own. */
#if !SDL_ATOMIC_DISABLED
static SDL_SpinLock lock = 0;
SDL_AtomicLock_REAL(&lock);
#endif
if (!already_initialized) {
SDL_InitDynamicAPILocked();
already_initialized = SDL_TRUE;
}
#if !SDL_ATOMIC_DISABLED
SDL_AtomicUnlock_REAL(&lock);
#endif
}
#endif /* SDL_DYNAMIC_API */
/* vi: set ts=4 sw=4 expandtab: */
SDL_dynapi.h
table
GLenum GLsizei GLenum GLenum const void * table
Definition: SDL_opengl_glext.h:3118
SDL_TRUE
Definition: SDL_stdinc.h:142
SDL_FALSE
Definition: SDL_stdinc.h:141
SDL_DYNAPI_jump_table
Definition: SDL_dynapi.c:121
get_sdlapi_entry
static SDL_INLINE void * get_sdlapi_entry(const char *fname, const char *sym)
Definition: SDL_dynapi.c:212
Uint32
uint32_t Uint32
Definition: SDL_stdinc.h:181
SDL_config.h
SDL_DYNAPI_ENTRYFN
Sint32(* SDL_DYNAPI_ENTRYFN)(Uint32 apiver, void *table, Uint32 tablesize)
Definition: SDL_dynapi.c:174
SDL_DYNAPI_VERSION
#define SDL_DYNAPI_VERSION
Definition: SDL_dynapi.c:48
retval
SDL_bool retval
Definition: testgamecontroller.c:65
DECLSPEC
#define DECLSPEC
Definition: SDL_internal.h:44
SDL_InitDynamicAPI
static void SDL_InitDynamicAPI(void)
Definition: SDL_dynapi.c:290
SDL_vulkan.h
SDL_dynapi_procs.h
jump_table
static SDL_DYNAPI_jump_table jump_table
Definition: SDL_dynapi.c:133
SDL_InitDynamicAPILocked
static void SDL_InitDynamicAPILocked(void)
Definition: SDL_dynapi.c:260
Sint32
int32_t Sint32
Definition: SDL_stdinc.h:175
NULL
#define NULL
Definition: begin_code.h:164
SDL_bool
SDL_bool
Definition: SDL_stdinc.h:139
lock
SDL_mutex * lock
Definition: SDL_events.c:78
SDL_DYNAPI_entry
Sint32 SDL_DYNAPI_entry(Uint32, void *, Uint32)
Definition: SDL_dynapi.c:178
SDL_INLINE
#define SDL_INLINE
Definition: begin_code.h:131
SDL_SpinLock
int SDL_SpinLock
Definition: SDL_atomic.h:89
SDL.h
SDL_DYNAPI_VARARGS
#define SDL_DYNAPI_VARARGS(_static, name, initcall)
Definition: SDL_dynapi.c:71
SDLCALL
#define SDLCALL
Definition: SDL_internal.h:45
SDL_syswm.h