SDL_dynapi.c (11118B)
1/* 2 Simple DirectMedia Layer 3 Copyright (C) 1997-2014 Sam Lantinga <slouken@libsdl.org> 4 5 This software is provided 'as-is', without any express or implied 6 warranty. In no event will the authors be held liable for any damages 7 arising from the use of this software. 8 9 Permission is granted to anyone to use this software for any purpose, 10 including commercial applications, and to alter it and redistribute it 11 freely, subject to the following restrictions: 12 13 1. The origin of this software must not be misrepresented; you must not 14 claim that you wrote the original software. If you use this software 15 in a product, an acknowledgment in the product documentation would be 16 appreciated but is not required. 17 2. Altered source versions must be plainly marked as such, and must not be 18 misrepresented as being the original software. 19 3. This notice may not be removed or altered from any source distribution. 20*/ 21 22#include "SDL_config.h" 23#include "SDL_dynapi.h" 24 25#if SDL_DYNAMIC_API 26 27#include "SDL.h" 28 29/* !!! FIXME: Shouldn't these be included in SDL.h? */ 30#include "SDL_shape.h" 31#include "SDL_syswm.h" 32 33/* This is the version of the dynamic API. This doesn't match the SDL version 34 and should not change until there's been a major revamp in API/ABI. 35 So 2.0.5 adds functions over 2.0.4? This number doesn't change; 36 the sizeof (jump_table) changes instead. But 2.1.0 changes how a function 37 works in an incompatible way or removes a function? This number changes, 38 since sizeof (jump_table) isn't sufficient anymore. It's likely 39 we'll forget to bump every time we add a function, so this is the 40 failsafe switch for major API change decisions. Respect it and use it 41 sparingly. */ 42#define SDL_DYNAPI_VERSION 1 43 44static void SDL_InitDynamicAPI(void); 45 46 47/* BE CAREFUL CALLING ANY SDL CODE IN HERE, IT WILL BLOW UP. 48 Even self-contained stuff might call SDL_Error and break everything. */ 49 50 51/* behold, the macro salsa! */ 52 53/* !!! FIXME: ...disabled...until we write it. :) */ 54#define DISABLE_JUMP_MAGIC 1 55 56#if DISABLE_JUMP_MAGIC 57/* Can't use the macro for varargs nonsense. This is atrocious. */ 58#define SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, logname, prio) \ 59 _static void SDL_Log##logname##name(int category, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \ 60 va_list ap; initcall; va_start(ap, fmt); \ 61 jump_table.SDL_LogMessageV(category, SDL_LOG_PRIORITY_##prio, fmt, ap); \ 62 va_end(ap); \ 63 } 64 65#define SDL_DYNAPI_VARARGS(_static, name, initcall) \ 66 _static int SDL_SetError##name(SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \ 67 char buf[512]; /* !!! FIXME: dynamic allocation */ \ 68 va_list ap; initcall; va_start(ap, fmt); \ 69 jump_table.SDL_vsnprintf(buf, sizeof (buf), fmt, ap); \ 70 va_end(ap); \ 71 return jump_table.SDL_SetError("%s", buf); \ 72 } \ 73 _static int SDL_sscanf##name(const char *buf, SDL_SCANF_FORMAT_STRING const char *fmt, ...) { \ 74 int retval; va_list ap; initcall; va_start(ap, fmt); \ 75 retval = jump_table.SDL_vsscanf(buf, fmt, ap); \ 76 va_end(ap); \ 77 return retval; \ 78 } \ 79 _static int SDL_snprintf##name(SDL_OUT_Z_CAP(maxlen) char *buf, size_t maxlen, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \ 80 int retval; va_list ap; initcall; va_start(ap, fmt); \ 81 retval = jump_table.SDL_vsnprintf(buf, maxlen, fmt, ap); \ 82 va_end(ap); \ 83 return retval; \ 84 } \ 85 _static void SDL_Log##name(SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \ 86 va_list ap; initcall; va_start(ap, fmt); \ 87 jump_table.SDL_LogMessageV(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO, fmt, ap); \ 88 va_end(ap); \ 89 } \ 90 _static void SDL_LogMessage##name(int category, SDL_LogPriority priority, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \ 91 va_list ap; initcall; va_start(ap, fmt); \ 92 jump_table.SDL_LogMessageV(category, priority, fmt, ap); \ 93 va_end(ap); \ 94 } \ 95 SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Verbose, VERBOSE) \ 96 SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Debug, DEBUG) \ 97 SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Info, INFO) \ 98 SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Warn, WARN) \ 99 SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Error, ERROR) \ 100 SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Critical, CRITICAL) 101#endif 102 103 104/* Typedefs for function pointers for jump table, and predeclare funcs */ 105/* The DEFAULT funcs will init jump table and then call real function. */ 106/* The REAL funcs are the actual functions, name-mangled to not clash. */ 107#define SDL_DYNAPI_PROC(rc,fn,params,args,ret) \ 108 typedef rc (*SDL_DYNAPIFN_##fn) params; \ 109 static rc fn##_DEFAULT params; \ 110 extern rc fn##_REAL params; 111#include "SDL_dynapi_procs.h" 112#undef SDL_DYNAPI_PROC 113 114/* The jump table! */ 115typedef struct { 116 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) SDL_DYNAPIFN_##fn fn; 117 #include "SDL_dynapi_procs.h" 118 #undef SDL_DYNAPI_PROC 119} SDL_DYNAPI_jump_table; 120 121/* Predeclare the default functions for initializing the jump table. */ 122#define SDL_DYNAPI_PROC(rc,fn,params,args,ret) static rc fn##_DEFAULT params; 123#include "SDL_dynapi_procs.h" 124#undef SDL_DYNAPI_PROC 125 126/* The actual jump table. */ 127static SDL_DYNAPI_jump_table jump_table = { 128 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) fn##_DEFAULT, 129 #include "SDL_dynapi_procs.h" 130 #undef SDL_DYNAPI_PROC 131}; 132 133/* Default functions init the function table then call right thing. */ 134#if DISABLE_JUMP_MAGIC 135#define SDL_DYNAPI_PROC(rc,fn,params,args,ret) \ 136 static rc fn##_DEFAULT params { \ 137 SDL_InitDynamicAPI(); \ 138 ret jump_table.fn args; \ 139 } 140#define SDL_DYNAPI_PROC_NO_VARARGS 1 141#include "SDL_dynapi_procs.h" 142#undef SDL_DYNAPI_PROC 143#undef SDL_DYNAPI_PROC_NO_VARARGS 144SDL_DYNAPI_VARARGS(static, _DEFAULT, SDL_InitDynamicAPI()) 145#else 146/* !!! FIXME: need the jump magic. */ 147#error Write me. 148#endif 149 150/* Public API functions to jump into the jump table. */ 151#if DISABLE_JUMP_MAGIC 152#define SDL_DYNAPI_PROC(rc,fn,params,args,ret) \ 153 rc fn params { ret jump_table.fn args; } 154#define SDL_DYNAPI_PROC_NO_VARARGS 1 155#include "SDL_dynapi_procs.h" 156#undef SDL_DYNAPI_PROC 157#undef SDL_DYNAPI_PROC_NO_VARARGS 158SDL_DYNAPI_VARARGS(,,) 159#else 160/* !!! FIXME: need the jump magic. */ 161#error Write me. 162#endif 163 164 165 166/* Here's the exported entry point that fills in the jump table. */ 167/* Use specific types when an "int" might suffice to keep this sane. */ 168typedef Sint32 (SDLCALL *SDL_DYNAPI_ENTRYFN)(Uint32 apiver, void *table, Uint32 tablesize); 169extern DECLSPEC Sint32 SDLCALL SDL_DYNAPI_entry(Uint32, void *, Uint32); 170 171Sint32 172SDL_DYNAPI_entry(Uint32 apiver, void *table, Uint32 tablesize) 173{ 174 SDL_DYNAPI_jump_table *output_jump_table = (SDL_DYNAPI_jump_table *) table; 175 176 if (apiver != SDL_DYNAPI_VERSION) { 177 /* !!! FIXME: can maybe handle older versions? */ 178 return -1; /* not compatible. */ 179 } else if (tablesize > sizeof (jump_table)) { 180 return -1; /* newer version of SDL with functions we can't provide. */ 181 } 182 183 /* Init our jump table first. */ 184 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) jump_table.fn = fn##_REAL; 185 #include "SDL_dynapi_procs.h" 186 #undef SDL_DYNAPI_PROC 187 188 /* Then the external table... */ 189 if (output_jump_table != &jump_table) { 190 jump_table.SDL_memcpy(output_jump_table, &jump_table, tablesize); 191 } 192 193 /* Safe to call SDL functions now; jump table is initialized! */ 194 195 return 0; /* success! */ 196} 197 198 199/* Obviously we can't use SDL_LoadObject() to load SDL. :) */ 200/* Also obviously, we never close the loaded library. */ 201#if defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__) 202#ifndef WIN32_LEAN_AND_MEAN 203#define WIN32_LEAN_AND_MEAN 1 204#endif 205#include <windows.h> 206static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym) 207{ 208 HANDLE lib = LoadLibraryA(fname); 209 return lib ? GetProcAddress(lib, sym) : NULL; 210} 211 212#elif defined(__HAIKU__) 213#include <os/kernel/image.h> 214static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym) 215{ 216 image_id lib = load_add_on(fname); 217 void *retval = NULL; 218 if ((lib < 0) || (get_image_symbol(lib, sym, B_SYMBOL_TYPE_TEXT, &retval) != B_NO_ERROR)) { 219 retval = NULL; 220 } 221 return retval; 222} 223#elif defined(unix) || defined(__unix__) || defined(__APPLE__) 224#include <dlfcn.h> 225static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym) 226{ 227 void *lib = dlopen(fname, RTLD_NOW | RTLD_LOCAL); 228 return lib ? dlsym(lib, sym) : NULL; 229} 230#else 231#error Please define your platform. 232#endif 233 234 235static void 236SDL_InitDynamicAPILocked(void) 237{ 238 const char *libname = SDL_getenv_REAL("SDL_DYNAMIC_API"); 239 SDL_DYNAPI_ENTRYFN entry = SDL_DYNAPI_entry; /* funcs from here by default. */ 240 241 if (libname) { 242 entry = (SDL_DYNAPI_ENTRYFN) get_sdlapi_entry(libname, "SDL_DYNAPI_entry"); 243 if (!entry) { 244 /* !!! FIXME: fail to startup here instead? */ 245 /* !!! FIXME: definitely warn user. */ 246 /* Just fill in the function pointers from this library. */ 247 entry = SDL_DYNAPI_entry; 248 } 249 } 250 251 if (entry(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table)) < 0) { 252 /* !!! FIXME: fail to startup here instead? */ 253 /* !!! FIXME: definitely warn user. */ 254 /* Just fill in the function pointers from this library. */ 255 if (entry != SDL_DYNAPI_entry) { 256 if (!SDL_DYNAPI_entry(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table))) { 257 /* !!! FIXME: now we're screwed. Should definitely abort now. */ 258 } 259 } 260 } 261 262 /* we intentionally never close the newly-loaded lib, of course. */ 263} 264 265static void 266SDL_InitDynamicAPI(void) 267{ 268 /* So the theory is that every function in the jump table defaults to 269 * calling this function, and then replaces itself with a version that 270 * doesn't call this function anymore. But it's possible that, in an 271 * extreme corner case, you can have a second thread hit this function 272 * while the jump table is being initialized by the first. 273 * In this case, a spinlock is really painful compared to what spinlocks 274 * _should_ be used for, but this would only happen once, and should be 275 * insanely rare, as you would have to spin a thread outside of SDL (as 276 * SDL_CreateThread() would also call this function before building the 277 * new thread). 278 */ 279 static volatile SDL_bool already_initialized = SDL_FALSE; 280 281 /* SDL_AtomicLock calls SDL mutex functions to emulate if 282 SDL_ATOMIC_DISABLED, which we can't do here, so in such a 283 configuration, you're on your own. */ 284 #if !SDL_ATOMIC_DISABLED 285 static SDL_SpinLock lock = 0; 286 SDL_AtomicLock_REAL(&lock); 287 #endif 288 289 if (!already_initialized) { 290 SDL_InitDynamicAPILocked(); 291 already_initialized = SDL_TRUE; 292 } 293 294 #if !SDL_ATOMIC_DISABLED 295 SDL_AtomicUnlock_REAL(&lock); 296 #endif 297} 298 299#endif /* SDL_DYNAMIC_API */ 300 301/* vi: set ts=4 sw=4 expandtab: */ 302