SDL  2.0
SDL_dynapi.c
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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 <os2.h>
31 #include <dos.h>
32 #endif
33 
34 #include "SDL.h"
35 
36 /* These headers have system specific definitions, so aren't included above */
37 #include "SDL_syswm.h"
38 #include "SDL_vulkan.h"
39 
40 /* This is the version of the dynamic API. This doesn't match the SDL version
41  and should not change until there's been a major revamp in API/ABI.
42  So 2.0.5 adds functions over 2.0.4? This number doesn't change;
43  the sizeof (jump_table) changes instead. But 2.1.0 changes how a function
44  works in an incompatible way or removes a function? This number changes,
45  since sizeof (jump_table) isn't sufficient anymore. It's likely
46  we'll forget to bump every time we add a function, so this is the
47  failsafe switch for major API change decisions. Respect it and use it
48  sparingly. */
49 #define SDL_DYNAPI_VERSION 1
50 
51 static void SDL_InitDynamicAPI(void);
52 
53 
54 /* BE CAREFUL CALLING ANY SDL CODE IN HERE, IT WILL BLOW UP.
55  Even self-contained stuff might call SDL_Error and break everything. */
56 
57 
58 /* behold, the macro salsa! */
59 
60 /* !!! FIXME: ...disabled...until we write it. :) */
61 #define DISABLE_JUMP_MAGIC 1
62 
63 #if DISABLE_JUMP_MAGIC
64 /* Can't use the macro for varargs nonsense. This is atrocious. */
65 #define SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, logname, prio) \
66  _static void SDLCALL SDL_Log##logname##name(int category, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
67  va_list ap; initcall; va_start(ap, fmt); \
68  jump_table.SDL_LogMessageV(category, SDL_LOG_PRIORITY_##prio, fmt, ap); \
69  va_end(ap); \
70  }
71 
72 #define SDL_DYNAPI_VARARGS(_static, name, initcall) \
73  _static int SDLCALL SDL_SetError##name(SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
74  char buf[512]; /* !!! FIXME: dynamic allocation */ \
75  va_list ap; initcall; va_start(ap, fmt); \
76  jump_table.SDL_vsnprintf(buf, sizeof (buf), fmt, ap); \
77  va_end(ap); \
78  return jump_table.SDL_SetError("%s", buf); \
79  } \
80  _static int SDLCALL SDL_sscanf##name(const char *buf, SDL_SCANF_FORMAT_STRING const char *fmt, ...) { \
81  int retval; va_list ap; initcall; va_start(ap, fmt); \
82  retval = jump_table.SDL_vsscanf(buf, fmt, ap); \
83  va_end(ap); \
84  return retval; \
85  } \
86  _static int SDLCALL SDL_snprintf##name(SDL_OUT_Z_CAP(maxlen) char *buf, size_t maxlen, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
87  int retval; va_list ap; initcall; va_start(ap, fmt); \
88  retval = jump_table.SDL_vsnprintf(buf, maxlen, fmt, ap); \
89  va_end(ap); \
90  return retval; \
91  } \
92  _static void SDLCALL SDL_Log##name(SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
93  va_list ap; initcall; va_start(ap, fmt); \
94  jump_table.SDL_LogMessageV(SDL_LOG_CATEGORY_APPLICATION, SDL_LOG_PRIORITY_INFO, fmt, ap); \
95  va_end(ap); \
96  } \
97  _static void SDLCALL SDL_LogMessage##name(int category, SDL_LogPriority priority, SDL_PRINTF_FORMAT_STRING const char *fmt, ...) { \
98  va_list ap; initcall; va_start(ap, fmt); \
99  jump_table.SDL_LogMessageV(category, priority, fmt, ap); \
100  va_end(ap); \
101  } \
102  SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Verbose, VERBOSE) \
103  SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Debug, DEBUG) \
104  SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Info, INFO) \
105  SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Warn, WARN) \
106  SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Error, ERROR) \
107  SDL_DYNAPI_VARARGS_LOGFN(_static, name, initcall, Critical, CRITICAL)
108 #endif
109 
110 
111 /* Typedefs for function pointers for jump table, and predeclare funcs */
112 /* The DEFAULT funcs will init jump table and then call real function. */
113 /* The REAL funcs are the actual functions, name-mangled to not clash. */
114 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) \
115  typedef rc (SDLCALL *SDL_DYNAPIFN_##fn) params; \
116  static rc SDLCALL fn##_DEFAULT params; \
117  extern rc SDLCALL fn##_REAL params;
118 #include "SDL_dynapi_procs.h"
119 #undef SDL_DYNAPI_PROC
120 
121 /* The jump table! */
122 typedef struct {
123  #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) SDL_DYNAPIFN_##fn fn;
124  #include "SDL_dynapi_procs.h"
125  #undef SDL_DYNAPI_PROC
127 
128 /* Predeclare the default functions for initializing the jump table. */
129 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) static rc SDLCALL fn##_DEFAULT params;
130 #include "SDL_dynapi_procs.h"
131 #undef SDL_DYNAPI_PROC
132 
133 /* The actual jump table. */
135  #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) fn##_DEFAULT,
136  #include "SDL_dynapi_procs.h"
137  #undef SDL_DYNAPI_PROC
138 };
139 
140 /* Default functions init the function table then call right thing. */
141 #if DISABLE_JUMP_MAGIC
142 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) \
143  static rc SDLCALL fn##_DEFAULT params { \
144  SDL_InitDynamicAPI(); \
145  ret jump_table.fn args; \
146  }
147 #define SDL_DYNAPI_PROC_NO_VARARGS 1
148 #include "SDL_dynapi_procs.h"
149 #undef SDL_DYNAPI_PROC
150 #undef SDL_DYNAPI_PROC_NO_VARARGS
151 SDL_DYNAPI_VARARGS(static, _DEFAULT, SDL_InitDynamicAPI())
152 #else
153 /* !!! FIXME: need the jump magic. */
154 #error Write me.
155 #endif
156 
157 /* Public API functions to jump into the jump table. */
158 #if DISABLE_JUMP_MAGIC
159 #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) \
160  rc SDLCALL fn params { ret jump_table.fn args; }
161 #define SDL_DYNAPI_PROC_NO_VARARGS 1
162 #include "SDL_dynapi_procs.h"
163 #undef SDL_DYNAPI_PROC
164 #undef SDL_DYNAPI_PROC_NO_VARARGS
166 #else
167 /* !!! FIXME: need the jump magic. */
168 #error Write me.
169 #endif
170 
171 /* we make this a static function so we can call the correct one without the
172  system's dynamic linker resolving to the wrong version of this. */
173 static Sint32
174 initialize_jumptable(Uint32 apiver, void *table, Uint32 tablesize)
175 {
176  SDL_DYNAPI_jump_table *output_jump_table = (SDL_DYNAPI_jump_table *) table;
177 
178  if (apiver != SDL_DYNAPI_VERSION) {
179  /* !!! FIXME: can maybe handle older versions? */
180  return -1; /* not compatible. */
181  } else if (tablesize > sizeof (jump_table)) {
182  return -1; /* newer version of SDL with functions we can't provide. */
183  }
184 
185  /* Init our jump table first. */
186  #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) jump_table.fn = fn##_REAL;
187  #include "SDL_dynapi_procs.h"
188  #undef SDL_DYNAPI_PROC
189 
190  /* Then the external table... */
191  if (output_jump_table != &jump_table) {
192  jump_table.SDL_memcpy(output_jump_table, &jump_table, tablesize);
193  }
194 
195  /* Safe to call SDL functions now; jump table is initialized! */
196 
197  return 0; /* success! */
198 }
199 
200 
201 /* Here's the exported entry point that fills in the jump table. */
202 /* Use specific types when an "int" might suffice to keep this sane. */
203 typedef Sint32 (SDLCALL *SDL_DYNAPI_ENTRYFN)(Uint32 apiver, void *table, Uint32 tablesize);
205 
206 Sint32
207 SDL_DYNAPI_entry(Uint32 apiver, void *table, Uint32 tablesize)
208 {
209  return initialize_jumptable(apiver, table, tablesize);
210 }
211 
212 
213 /* Obviously we can't use SDL_LoadObject() to load SDL. :) */
214 /* Also obviously, we never close the loaded library. */
215 #if defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__)
216 #ifndef WIN32_LEAN_AND_MEAN
217 #define WIN32_LEAN_AND_MEAN 1
218 #endif
219 #include <windows.h>
220 static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym)
221 {
222  HANDLE lib = LoadLibraryA(fname);
223  void *retval = NULL;
224  if (lib) {
225  retval = GetProcAddress(lib, sym);
226  if (retval == NULL) {
227  FreeLibrary(lib);
228  }
229  }
230  return retval;
231 }
232 
233 #elif defined(unix) || defined(__unix__) || defined(__APPLE__) || defined(__HAIKU__) || defined(__QNX__)
234 #include <dlfcn.h>
235 static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym)
236 {
237  void *lib = dlopen(fname, RTLD_NOW | RTLD_LOCAL);
238  void *retval = NULL;
239  if (lib != NULL) {
240  retval = dlsym(lib, sym);
241  if (retval == NULL) {
242  dlclose(lib);
243  }
244  }
245  return retval;
246 }
247 
248 #elif defined(__OS2__)
249 static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym)
250 {
251  HMODULE hmodule;
252  PFN retval = NULL;
253  char error[256];
254  if (DosLoadModule(&error, sizeof(error), fname, &hmodule) == NO_ERROR) {
255  if (DosQueryProcAddr(hmodule, 0, sym, &retval) != NO_ERROR) {
256  DosFreeModule(hmodule);
257  }
258  }
259  return (void *) retval;
260 }
261 
262 #else
263 #error Please define your platform.
264 #endif
265 
266 
267 static void
269 {
270  const char *libname = SDL_getenv_REAL("SDL_DYNAMIC_API");
271  SDL_DYNAPI_ENTRYFN entry = NULL; /* funcs from here by default. */
272 
273  if (libname) {
274  entry = (SDL_DYNAPI_ENTRYFN) get_sdlapi_entry(libname, "SDL_DYNAPI_entry");
275  if (!entry) {
276  /* !!! FIXME: fail to startup here instead? */
277  /* !!! FIXME: definitely warn user. */
278  /* Just fill in the function pointers from this library. */
279  }
280  }
281 
282  if (!entry || (entry(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table)) < 0)) {
283  /* !!! FIXME: fail to startup here instead? */
284  /* !!! FIXME: definitely warn user. */
285  /* Just fill in the function pointers from this library. */
286  if (!entry) {
288  /* !!! FIXME: now we're screwed. Should definitely abort now. */
289  }
290  }
291  }
292 
293  /* we intentionally never close the newly-loaded lib, of course. */
294 }
295 
296 static void
298 {
299  /* So the theory is that every function in the jump table defaults to
300  * calling this function, and then replaces itself with a version that
301  * doesn't call this function anymore. But it's possible that, in an
302  * extreme corner case, you can have a second thread hit this function
303  * while the jump table is being initialized by the first.
304  * In this case, a spinlock is really painful compared to what spinlocks
305  * _should_ be used for, but this would only happen once, and should be
306  * insanely rare, as you would have to spin a thread outside of SDL (as
307  * SDL_CreateThread() would also call this function before building the
308  * new thread).
309  */
310  static SDL_bool already_initialized = SDL_FALSE;
311 
312  /* SDL_AtomicLock calls SDL mutex functions to emulate if
313  SDL_ATOMIC_DISABLED, which we can't do here, so in such a
314  configuration, you're on your own. */
315  #if !SDL_ATOMIC_DISABLED
316  static SDL_SpinLock lock = 0;
317  SDL_AtomicLock_REAL(&lock);
318  #endif
319 
320  if (!already_initialized) {
322  already_initialized = SDL_TRUE;
323  }
324 
325  #if !SDL_ATOMIC_DISABLED
326  SDL_AtomicUnlock_REAL(&lock);
327  #endif
328 }
329 
330 #endif /* SDL_DYNAMIC_API */
331 
332 /* vi: set ts=4 sw=4 expandtab: */
SDL.h
DECLSPEC
#define DECLSPEC
Definition: SDL_internal.h:44
Sint32
int32_t Sint32
Definition: SDL_stdinc.h:197
NULL
#define NULL
Definition: begin_code.h:164
SDL_vulkan.h
SDLCALL
#define SDLCALL
Definition: SDL_internal.h:45
SDL_DYNAPI_entry
Sint32 SDL_DYNAPI_entry(Uint32, void *, Uint32)
Definition: SDL_dynapi.c:207
SDL_dynapi_procs.h
SDL_dynapi.h
Uint32
uint32_t Uint32
Definition: SDL_stdinc.h:203
SDL_DYNAPI_VARARGS
#define SDL_DYNAPI_VARARGS(_static, name, initcall)
Definition: SDL_dynapi.c:72
get_sdlapi_entry
static SDL_INLINE void * get_sdlapi_entry(const char *fname, const char *sym)
Definition: SDL_dynapi.c:220
initialize_jumptable
static Sint32 initialize_jumptable(Uint32 apiver, void *table, Uint32 tablesize)
Definition: SDL_dynapi.c:174
retval
SDL_bool retval
Definition: testgamecontroller.c:65
SDL_INLINE
#define SDL_INLINE
Definition: begin_code.h:131
jump_table
static SDL_DYNAPI_jump_table jump_table
Definition: SDL_dynapi.c:134
SDL_TRUE
@ SDL_TRUE
Definition: SDL_stdinc.h:164
SDL_InitDynamicAPI
static void SDL_InitDynamicAPI(void)
Definition: SDL_dynapi.c:297
SDL_SpinLock
int SDL_SpinLock
Definition: SDL_atomic.h:89
SDL_InitDynamicAPILocked
static void SDL_InitDynamicAPILocked(void)
Definition: SDL_dynapi.c:268
SDL_DYNAPI_jump_table
Definition: SDL_dynapi.c:122
SDL_DYNAPI_ENTRYFN
Sint32(* SDL_DYNAPI_ENTRYFN)(Uint32 apiver, void *table, Uint32 tablesize)
Definition: SDL_dynapi.c:203
SDL_bool
SDL_bool
Definition: SDL_stdinc.h:162
SDL_DYNAPI_VERSION
#define SDL_DYNAPI_VERSION
Definition: SDL_dynapi.c:49
SDL_FALSE
@ SDL_FALSE
Definition: SDL_stdinc.h:163
SDL_config.h
table
GLenum GLsizei GLenum GLenum const void * table
Definition: SDL_opengl_glext.h:3118
SDL_syswm.h
lock
SDL_mutex * lock
Definition: SDL_events.c:78