1 /*
2 Simple DirectMedia Layer
3 Copyright (C) 1997-2018 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 #if defined(__OS2__)
28 #define INCL_DOS
29 #define INCL_DOSERRORS
30 #include <dos.h>
31 #endif
32
33 #include "SDL.h"
34
35 /* These headers have system specific definitions, so aren't included above */
36 #include "SDL_syswm.h"
37 #include "SDL_vulkan.h"
38
39 /* This is the version of the dynamic API. This doesn't match the SDL version
40 and should not change until there's been a major revamp in API/ABI.
41 So 2.0.5 adds functions over 2.0.4? This number doesn't change;
42 the sizeof (jump_table) changes instead. But 2.1.0 changes how a function
43 works in an incompatible way or removes a function? This number changes,
44 since sizeof (jump_table) isn't sufficient anymore. It's likely
45 we'll forget to bump every time we add a function, so this is the
46 failsafe switch for major API change decisions. Respect it and use it
47 sparingly. */
48 #define SDL_DYNAPI_VERSION 1
49
50 static void SDL_InitDynamicAPI(void);
51
52
53 /* BE CAREFUL CALLING ANY SDL CODE IN HERE, IT WILL BLOW UP.
54 Even self-contained stuff might call SDL_Error and break everything. */
55
56
57 /* behold, the macro salsa! */
58
59 /* !!! FIXME: ...disabled...until we write it. :) */
60 #define DISABLE_JUMP_MAGIC 1
61
62 #if DISABLE_JUMP_MAGIC
63 /* Can't use the macro for varargs nonsense. This is atrocious. */
64 #define SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, logname, prio) \
65 _static void SDLCALL SDL_Log##logname##name(int category, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
66 va_list ap; initcall; va_start(ap, fmt); \
67 jump_table.SDL_LogMessageV(category, SDL_LOG_PRIORITY_##prio, fmt, ap); \
68 va_end(ap); \
69 }
70
71 #define SDL_DYNAPI_VARARGS(_static, name, initcall) \
72 _static int SDLCALL SDL_SetError##name(SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
73 char buf[512]; /* !!! FIXME: dynamic allocation */ \
74 va_list ap; initcall; va_start(ap, fmt); \
75 jump_table.SDL_vsnprintf(buf, sizeof (buf), fmt, ap); \
76 va_end(ap); \
77 return jump_table.SDL_SetError("%s", buf); \
78 } \
79 _static int SDLCALL SDL_sscanf##name(const char *buf, SDL_SCANF_FORMAT_STRING const char *fmt, ...) { \
80 int retval; va_list ap; initcall; va_start(ap, fmt); \
81 retval = jump_table.SDL_vsscanf(buf, fmt, ap); \
82 va_end(ap); \
83 return retval; \
84 } \
85 _static int SDLCALL SDL_snprintf##name(SDL_OUT_Z_CAP(maxlen) char *buf, size_t maxlen, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
86 int retval; va_list ap; initcall; va_start(ap, fmt); \
87 retval = jump_table.SDL_vsnprintf(buf, maxlen, fmt, ap); \
88 va_end(ap); \
89 return retval; \
90 } \
91 _static void SDLCALL SDL_Log##name(SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
92 va_list ap; initcall; va_start(ap, fmt); \
93 jump_table.SDL_LogMessageV(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO, fmt, ap); \
94 va_end(ap); \
95 } \
96 _static void SDLCALL SDL_LogMessage##name(int category, SDL_LogPriority priority, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
97 va_list ap; initcall; va_start(ap, fmt); \
98 jump_table.SDL_LogMessageV(category, priority, fmt, ap); \
99 va_end(ap); \
100 } \
101 SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Verbose, VERBOSE) \
102 SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Debug, DEBUG) \
103 SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Info, INFO) \
104 SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Warn, WARN) \
105 SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Error, ERROR) \
106 SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Critical, CRITICAL)
107 #endif
108
109
110 /* Typedefs for function pointers for jump table, and predeclare funcs */
111 /* The DEFAULT funcs will init jump table and then call real function. */
112 /* The REAL funcs are the actual functions, name-mangled to not clash. */
113 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) \
114 typedef rc (SDLCALL *SDL_DYNAPIFN_##fn) params; \
115 static rc SDLCALL fn##_DEFAULT params; \
116 extern rc SDLCALL fn##_REAL params;
117 #include "SDL_dynapi_procs.h"
118 #undef SDL_DYNAPI_PROC
119
120 /* The jump table! */
121 typedef struct {
122 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) SDL_DYNAPIFN_##fn fn;
123 #include "SDL_dynapi_procs.h"
124 #undef SDL_DYNAPI_PROC
125 } SDL_DYNAPI_jump_table;
126
127 /* Predeclare the default functions for initializing the jump table. */
128 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) static rc SDLCALL fn##_DEFAULT params;
129 #include "SDL_dynapi_procs.h"
130 #undef SDL_DYNAPI_PROC
131
132 /* The actual jump table. */
133 static SDL_DYNAPI_jump_table jump_table = {
134 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) fn##_DEFAULT,
135 #include "SDL_dynapi_procs.h"
136 #undef SDL_DYNAPI_PROC
137 };
138
139 /* Default functions init the function table then call right thing. */
140 #if DISABLE_JUMP_MAGIC
141 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) \
142 static rc SDLCALL fn##_DEFAULT params { \
143 SDL_InitDynamicAPI(); \
144 ret jump_table.fn args; \
145 }
146 #define SDL_DYNAPI_PROC_NO_VARARGS 1
147 #include "SDL_dynapi_procs.h"
148 #undef SDL_DYNAPI_PROC
149 #undef SDL_DYNAPI_PROC_NO_VARARGS
150 SDL_DYNAPI_VARARGS(static, _DEFAULT, SDL_InitDynamicAPI())
151 #else
152 /* !!! FIXME: need the jump magic. */
153 #error Write me.
154 #endif
155
156 /* Public API functions to jump into the jump table. */
157 #if DISABLE_JUMP_MAGIC
158 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) \
159 rc SDLCALL fn params { ret jump_table.fn args; }
160 #define SDL_DYNAPI_PROC_NO_VARARGS 1
161 #include "SDL_dynapi_procs.h"
162 #undef SDL_DYNAPI_PROC
163 #undef SDL_DYNAPI_PROC_NO_VARARGS
164 SDL_DYNAPI_VARARGS(,,)
165 #else
166 /* !!! FIXME: need the jump magic. */
167 #error Write me.
168 #endif
169
170
171
172 /* Here's the exported entry point that fills in the jump table. */
173 /* Use specific types when an "int" might suffice to keep this sane. */
174 typedef Sint32 (SDLCALL *SDL_DYNAPI_ENTRYFN)(Uint32 apiver, void *table, Uint32 tablesize);
175 extern DECLSPEC Sint32 SDLCALL SDL_DYNAPI_entry(Uint32, void *, Uint32);
176
177 Sint32
SDL_DYNAPI_entry(Uint32 apiver,void * table,Uint32 tablesize)178 SDL_DYNAPI_entry(Uint32 apiver, void *table, Uint32 tablesize)
179 {
180 SDL_DYNAPI_jump_table *output_jump_table = (SDL_DYNAPI_jump_table *) table;
181
182 if (apiver != SDL_DYNAPI_VERSION) {
183 /* !!! FIXME: can maybe handle older versions? */
184 return -1; /* not compatible. */
185 } else if (tablesize > sizeof (jump_table)) {
186 return -1; /* newer version of SDL with functions we can't provide. */
187 }
188
189 /* Init our jump table first. */
190 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) jump_table.fn = fn##_REAL;
191 #include "SDL_dynapi_procs.h"
192 #undef SDL_DYNAPI_PROC
193
194 /* Then the external table... */
195 if (output_jump_table != &jump_table) {
196 jump_table.SDL_memcpy(output_jump_table, &jump_table, tablesize);
197 }
198
199 /* Safe to call SDL functions now; jump table is initialized! */
200
201 return 0; /* success! */
202 }
203
204
205 /* Obviously we can't use SDL_LoadObject() to load SDL. :) */
206 /* Also obviously, we never close the loaded library. */
207 #if defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__)
208 #ifndef WIN32_LEAN_AND_MEAN
209 #define WIN32_LEAN_AND_MEAN 1
210 #endif
211 #include <windows.h>
get_sdlapi_entry(const char * fname,const char * sym)212 static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym)
213 {
214 HANDLE lib = LoadLibraryA(fname);
215 void *retval = NULL;
216 if (lib) {
217 retval = GetProcAddress(lib, sym);
218 if (retval == NULL) {
219 FreeLibrary(lib);
220 }
221 }
222 return retval;
223 }
224
225 #elif defined(unix) || defined(__unix__) || defined(__APPLE__) || defined(__HAIKU__) || defined(__QNX__)
226 #include <dlfcn.h>
get_sdlapi_entry(const char * fname,const char * sym)227 static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym)
228 {
229 void *lib = dlopen(fname, RTLD_NOW | RTLD_LOCAL);
230 void *retval = NULL;
231 if (lib != NULL) {
232 retval = dlsym(lib, sym);
233 if (retval == NULL) {
234 dlclose(lib);
235 }
236 }
237 return retval;
238 }
239
240 #elif defined(__OS2__)
get_sdlapi_entry(const char * fname,const char * sym)241 static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym)
242 {
243 HMODULE hmodule;
244 PFN retval = NULL;
245 char error[256];
246 if (DosLoadModule(&error, sizeof(error), fname, &hmodule) == NO_ERROR) {
247 if (DosQueryProcAddr(hmodule, 0, sym, &retval) != NO_ERROR) {
248 DosFreeModule(hmodule);
249 }
250 }
251 return (void *) retval;
252 }
253
254 #else
255 #error Please define your platform.
256 #endif
257
258
259 static void
SDL_InitDynamicAPILocked(void)260 SDL_InitDynamicAPILocked(void)
261 {
262 const char *libname = SDL_getenv_REAL("SDL_DYNAMIC_API");
263 SDL_DYNAPI_ENTRYFN entry = SDL_DYNAPI_entry; /* funcs from here by default. */
264
265 if (libname) {
266 entry = (SDL_DYNAPI_ENTRYFN) get_sdlapi_entry(libname, "SDL_DYNAPI_entry");
267 if (!entry) {
268 /* !!! FIXME: fail to startup here instead? */
269 /* !!! FIXME: definitely warn user. */
270 /* Just fill in the function pointers from this library. */
271 entry = SDL_DYNAPI_entry;
272 }
273 }
274
275 if (entry(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table)) < 0) {
276 /* !!! FIXME: fail to startup here instead? */
277 /* !!! FIXME: definitely warn user. */
278 /* Just fill in the function pointers from this library. */
279 if (entry != SDL_DYNAPI_entry) {
280 if (!SDL_DYNAPI_entry(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table))) {
281 /* !!! FIXME: now we're screwed. Should definitely abort now. */
282 }
283 }
284 }
285
286 /* we intentionally never close the newly-loaded lib, of course. */
287 }
288
289 static void
SDL_InitDynamicAPI(void)290 SDL_InitDynamicAPI(void)
291 {
292 /* So the theory is that every function in the jump table defaults to
293 * calling this function, and then replaces itself with a version that
294 * doesn't call this function anymore. But it's possible that, in an
295 * extreme corner case, you can have a second thread hit this function
296 * while the jump table is being initialized by the first.
297 * In this case, a spinlock is really painful compared to what spinlocks
298 * _should_ be used for, but this would only happen once, and should be
299 * insanely rare, as you would have to spin a thread outside of SDL (as
300 * SDL_CreateThread() would also call this function before building the
301 * new thread).
302 */
303 static SDL_bool already_initialized = SDL_FALSE;
304
305 /* SDL_AtomicLock calls SDL mutex functions to emulate if
306 SDL_ATOMIC_DISABLED, which we can't do here, so in such a
307 configuration, you're on your own. */
308 #if !SDL_ATOMIC_DISABLED
309 static SDL_SpinLock lock = 0;
310 SDL_AtomicLock_REAL(&lock);
311 #endif
312
313 if (!already_initialized) {
314 SDL_InitDynamicAPILocked();
315 already_initialized = SDL_TRUE;
316 }
317
318 #if !SDL_ATOMIC_DISABLED
319 SDL_AtomicUnlock_REAL(&lock);
320 #endif
321 }
322
323 #endif /* SDL_DYNAMIC_API */
324
325 /* vi: set ts=4 sw=4 expandtab: */
326