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 <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
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
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. */
134  #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) fn##_DEFAULT,
135  #include "SDL_dynapi_procs.h"
136  #undef SDL_DYNAPI_PROC
137 };
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
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
165 #else
166 /* !!! FIXME: need the jump magic. */
167 #error Write me.
168 #endif
169 
170 /* we make this a static function so we can call the correct one without the
171  system's dynamic linker resolving to the wrong version of this. */
172 static Sint32
173 initialize_jumptable(Uint32 apiver, void *table, Uint32 tablesize)
174 {
175  SDL_DYNAPI_jump_table *output_jump_table = (SDL_DYNAPI_jump_table *) table;
177  if (apiver != SDL_DYNAPI_VERSION) {
178  /* !!! FIXME: can maybe handle older versions? */
179  return -1; /* not compatible. */
180  } else if (tablesize > sizeof (jump_table)) {
181  return -1; /* newer version of SDL with functions we can't provide. */
182  }
183 
184  /* Init our jump table first. */
185  #define SDL_DYNAPI_PROC(rc,fn,params,args,ret) jump_table.fn = fn##_REAL;
187  #undef SDL_DYNAPI_PROC
189  /* Then the external table... */
190  if (output_jump_table != &jump_table) {
191  jump_table.SDL_memcpy(output_jump_table, &jump_table, tablesize);
192  }
193 
194  /* Safe to call SDL functions now; jump table is initialized! */
195 
196  return 0; /* success! */
197 }
199 
200 /* Here's the exported entry point that fills in the jump table. */
201 /* Use specific types when an "int" might suffice to keep this sane. */
202 typedef Sint32 (SDLCALL *SDL_DYNAPI_ENTRYFN)(Uint32 apiver, void *table, Uint32 tablesize);
205 Sint32
206 SDL_DYNAPI_entry(Uint32 apiver, void *table, Uint32 tablesize)
207 {
208  return initialize_jumptable(apiver, table, tablesize);
209 }
211 
212 /* Obviously we can't use SDL_LoadObject() to load SDL. :) */
213 /* Also obviously, we never close the loaded library. */
214 #if defined(WIN32) || defined(_WIN32) || defined(__CYGWIN__)
215 #ifndef WIN32_LEAN_AND_MEAN
216 #define WIN32_LEAN_AND_MEAN 1
217 #endif
218 #include <windows.h>
219 static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym)
220 {
221  HANDLE lib = LoadLibraryA(fname);
222  void *retval = NULL;
223  if (lib) {
224  retval = GetProcAddress(lib, sym);
225  if (retval == NULL) {
226  FreeLibrary(lib);
227  }
228  }
229  return retval;
230 }
231 
232 #elif defined(unix) || defined(__unix__) || defined(__APPLE__) || defined(__HAIKU__) || defined(__QNX__)
233 #include <dlfcn.h>
234 static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym)
235 {
236  void *lib = dlopen(fname, RTLD_NOW | RTLD_LOCAL);
237  void *retval = NULL;
238  if (lib != NULL) {
239  retval = dlsym(lib, sym);
240  if (retval == NULL) {
241  dlclose(lib);
242  }
243  }
244  return retval;
245 }
247 #elif defined(__OS2__)
248 static SDL_INLINE void *get_sdlapi_entry(const char *fname, const char *sym)
249 {
250  HMODULE hmodule;
251  PFN retval = NULL;
252  char error[256];
253  if (DosLoadModule(&error, sizeof(error), fname, &hmodule) == NO_ERROR) {
254  if (DosQueryProcAddr(hmodule, 0, sym, &retval) != NO_ERROR) {
255  DosFreeModule(hmodule);
256  }
257  }
258  return (void *) retval;
259 }
261 #else
262 #error Please define your platform.
263 #endif
265 
266 static void
268 {
269  const char *libname = SDL_getenv_REAL("SDL_DYNAMIC_API");
270  SDL_DYNAPI_ENTRYFN entry = NULL; /* funcs from here by default. */
271 
272  if (libname) {
273  entry = (SDL_DYNAPI_ENTRYFN) get_sdlapi_entry(libname, "SDL_DYNAPI_entry");
274  if (!entry) {
275  /* !!! FIXME: fail to startup here instead? */
276  /* !!! FIXME: definitely warn user. */
277  /* Just fill in the function pointers from this library. */
278  }
279  }
281  if (!entry || (entry(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table)) < 0)) {
282  /* !!! FIXME: fail to startup here instead? */
283  /* !!! FIXME: definitely warn user. */
284  /* Just fill in the function pointers from this library. */
285  if (!entry) {
286  if (!initialize_jumptable(SDL_DYNAPI_VERSION, &jump_table, sizeof (jump_table))) {
287  /* !!! FIXME: now we're screwed. Should definitely abort now. */
288  }
289  }
290  }
291 
292  /* we intentionally never close the newly-loaded lib, of course. */
293 }
295 static void
297 {
298  /* So the theory is that every function in the jump table defaults to
299  * calling this function, and then replaces itself with a version that
300  * doesn't call this function anymore. But it's possible that, in an
301  * extreme corner case, you can have a second thread hit this function
302  * while the jump table is being initialized by the first.
303  * In this case, a spinlock is really painful compared to what spinlocks
304  * _should_ be used for, but this would only happen once, and should be
305  * insanely rare, as you would have to spin a thread outside of SDL (as
306  * SDL_CreateThread() would also call this function before building the
307  * new thread).
308  */
309  static SDL_bool already_initialized = SDL_FALSE;
311  /* SDL_AtomicLock calls SDL mutex functions to emulate if
312  SDL_ATOMIC_DISABLED, which we can't do here, so in such a
313  configuration, you're on your own. */
314  #if !SDL_ATOMIC_DISABLED
315  static SDL_SpinLock lock = 0;
316  SDL_AtomicLock_REAL(&lock);
317  #endif
319  if (!already_initialized) {
321  already_initialized = SDL_TRUE;
322  }
323 
324  #if !SDL_ATOMIC_DISABLED
325  SDL_AtomicUnlock_REAL(&lock);
326  #endif
327 }
329 #endif /* SDL_DYNAMIC_API */
331 /* vi: set ts=4 sw=4 expandtab: */
GLenum GLsizei GLenum GLenum const void * table
static SDL_INLINE void * get_sdlapi_entry(const char *fname, const char *sym)
Definition: SDL_dynapi.c:219
uint32_t Uint32
Definition: SDL_stdinc.h:181
Sint32(* SDL_DYNAPI_ENTRYFN)(Uint32 apiver, void *table, Uint32 tablesize)
Definition: SDL_dynapi.c:202
#define SDL_DYNAPI_VERSION
Definition: SDL_dynapi.c:48
SDL_bool retval
#define DECLSPEC
Definition: SDL_internal.h:44
static void SDL_InitDynamicAPI(void)
Definition: SDL_dynapi.c:296
static SDL_DYNAPI_jump_table jump_table
Definition: SDL_dynapi.c:133
static void SDL_InitDynamicAPILocked(void)
Definition: SDL_dynapi.c:267
int32_t Sint32
Definition: SDL_stdinc.h:175
#define NULL
Definition: begin_code.h:164
SDL_bool
Definition: SDL_stdinc.h:139
SDL_mutex * lock
Definition: SDL_events.c:78
Sint32 SDL_DYNAPI_entry(Uint32, void *, Uint32)
Definition: SDL_dynapi.c:206
#define SDL_INLINE
Definition: begin_code.h:131
int SDL_SpinLock
Definition: SDL_atomic.h:89
#define SDL_DYNAPI_VARARGS(_static, name, initcall)
Definition: SDL_dynapi.c:71
#define SDLCALL
Definition: SDL_internal.h:45
static Sint32 initialize_jumptable(Uint32 apiver, void *table, Uint32 tablesize)
Definition: SDL_dynapi.c:173