summaryrefslogtreecommitdiffstats
path: root/externals/gamemode/gamemode_client.h
blob: b9f64fe460ba5461dda8691bef76513d0524ea40 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
/*

Copyright (c) 2017-2019, Feral Interactive
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

 * Redistributions of source code must retain the above copyright notice,
   this list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright
   notice, this list of conditions and the following disclaimer in the
   documentation and/or other materials provided with the distribution.
 * Neither the name of Feral Interactive nor the names of its contributors
   may be used to endorse or promote products derived from this software
   without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

 */
#ifndef CLIENT_GAMEMODE_H
#define CLIENT_GAMEMODE_H
/*
 * GameMode supports the following client functions
 * Requests are refcounted in the daemon
 *
 * int gamemode_request_start() - Request gamemode starts
 *   0 if the request was sent successfully
 *   -1 if the request failed
 *
 * int gamemode_request_end() - Request gamemode ends
 *   0 if the request was sent successfully
 *   -1 if the request failed
 *
 * GAMEMODE_AUTO can be defined to make the above two functions apply during static init and
 * destruction, as appropriate. In this configuration, errors will be printed to stderr
 *
 * int gamemode_query_status() - Query the current status of gamemode
 *   0 if gamemode is inactive
 *   1 if gamemode is active
 *   2 if gamemode is active and this client is registered
 *   -1 if the query failed
 *
 * int gamemode_request_start_for(pid_t pid) - Request gamemode starts for another process
 *   0 if the request was sent successfully
 *   -1 if the request failed
 *   -2 if the request was rejected
 *
 * int gamemode_request_end_for(pid_t pid) - Request gamemode ends for another process
 *   0 if the request was sent successfully
 *   -1 if the request failed
 *   -2 if the request was rejected
 *
 * int gamemode_query_status_for(pid_t pid) - Query status of gamemode for another process
 *   0 if gamemode is inactive
 *   1 if gamemode is active
 *   2 if gamemode is active and this client is registered
 *   -1 if the query failed
 *
 * const char* gamemode_error_string() - Get an error string
 *   returns a string describing any of the above errors
 *
 * Note: All the above requests can be blocking - dbus requests can and will block while the daemon
 * handles the request. It is not recommended to make these calls in performance critical code
 */

#include <stdbool.h>
#include <stdio.h>

#include <dlfcn.h>
#include <string.h>

#include <assert.h>

#include <sys/types.h>

static char internal_gamemode_client_error_string[512] = { 0 };

/**
 * Load libgamemode dynamically to dislodge us from most dependencies.
 * This allows clients to link and/or use this regardless of runtime.
 * See SDL2 for an example of the reasoning behind this in terms of
 * dynamic versioning as well.
 */
static volatile int internal_libgamemode_loaded = 1;

/* Typedefs for the functions to load */
typedef int (*api_call_return_int)(void);
typedef const char *(*api_call_return_cstring)(void);
typedef int (*api_call_pid_return_int)(pid_t);

/* Storage for functors */
static api_call_return_int REAL_internal_gamemode_request_start = NULL;
static api_call_return_int REAL_internal_gamemode_request_end = NULL;
static api_call_return_int REAL_internal_gamemode_query_status = NULL;
static api_call_return_cstring REAL_internal_gamemode_error_string = NULL;
static api_call_pid_return_int REAL_internal_gamemode_request_start_for = NULL;
static api_call_pid_return_int REAL_internal_gamemode_request_end_for = NULL;
static api_call_pid_return_int REAL_internal_gamemode_query_status_for = NULL;

/**
 * Internal helper to perform the symbol binding safely.
 *
 * Returns 0 on success and -1 on failure
 */
__attribute__((always_inline)) static inline int internal_bind_libgamemode_symbol(
    void *handle, const char *name, void **out_func, size_t func_size, bool required)
{
	void *symbol_lookup = NULL;
	char *dl_error = NULL;

	/* Safely look up the symbol */
	symbol_lookup = dlsym(handle, name);
	dl_error = dlerror();
	if (required && (dl_error || !symbol_lookup)) {
		snprintf(internal_gamemode_client_error_string,
		         sizeof(internal_gamemode_client_error_string),
		         "dlsym failed - %s",
		         dl_error);
		return -1;
	}

	/* Have the symbol correctly, copy it to make it usable */
	memcpy(out_func, &symbol_lookup, func_size);
	return 0;
}

/**
 * Loads libgamemode and needed functions
 *
 * Returns 0 on success and -1 on failure
 */
__attribute__((always_inline)) static inline int internal_load_libgamemode(void)
{
	/* We start at 1, 0 is a success and -1 is a fail */
	if (internal_libgamemode_loaded != 1) {
		return internal_libgamemode_loaded;
	}

	/* Anonymous struct type to define our bindings */
	struct binding {
		const char *name;
		void **functor;
		size_t func_size;
		bool required;
	} bindings[] = {
		{ "real_gamemode_request_start",
		  (void **)&REAL_internal_gamemode_request_start,
		  sizeof(REAL_internal_gamemode_request_start),
		  true },
		{ "real_gamemode_request_end",
		  (void **)&REAL_internal_gamemode_request_end,
		  sizeof(REAL_internal_gamemode_request_end),
		  true },
		{ "real_gamemode_query_status",
		  (void **)&REAL_internal_gamemode_query_status,
		  sizeof(REAL_internal_gamemode_query_status),
		  false },
		{ "real_gamemode_error_string",
		  (void **)&REAL_internal_gamemode_error_string,
		  sizeof(REAL_internal_gamemode_error_string),
		  true },
		{ "real_gamemode_request_start_for",
		  (void **)&REAL_internal_gamemode_request_start_for,
		  sizeof(REAL_internal_gamemode_request_start_for),
		  false },
		{ "real_gamemode_request_end_for",
		  (void **)&REAL_internal_gamemode_request_end_for,
		  sizeof(REAL_internal_gamemode_request_end_for),
		  false },
		{ "real_gamemode_query_status_for",
		  (void **)&REAL_internal_gamemode_query_status_for,
		  sizeof(REAL_internal_gamemode_query_status_for),
		  false },
	};

	void *libgamemode = NULL;

	/* Try and load libgamemode */
	libgamemode = dlopen("libgamemode.so.0", RTLD_NOW);
	if (!libgamemode) {
		/* Attempt to load unversioned library for compatibility with older
		 * versions (as of writing, there are no ABI changes between the two -
		 * this may need to change if ever ABI-breaking changes are made) */
		libgamemode = dlopen("libgamemode.so", RTLD_NOW);
		if (!libgamemode) {
			snprintf(internal_gamemode_client_error_string,
			         sizeof(internal_gamemode_client_error_string),
			         "dlopen failed - %s",
			         dlerror());
			internal_libgamemode_loaded = -1;
			return -1;
		}
	}

	/* Attempt to bind all symbols */
	for (size_t i = 0; i < sizeof(bindings) / sizeof(bindings[0]); i++) {
		struct binding *binder = &bindings[i];

		if (internal_bind_libgamemode_symbol(libgamemode,
		                                     binder->name,
		                                     binder->functor,
		                                     binder->func_size,
		                                     binder->required)) {
			internal_libgamemode_loaded = -1;
			return -1;
		};
	}

	/* Success */
	internal_libgamemode_loaded = 0;
	return 0;
}

/**
 * Redirect to the real libgamemode
 */
__attribute__((always_inline)) static inline const char *gamemode_error_string(void)
{
	/* If we fail to load the system gamemode, or we have an error string already, return our error
	 * string instead of diverting to the system version */
	if (internal_load_libgamemode() < 0 || internal_gamemode_client_error_string[0] != '\0') {
		return internal_gamemode_client_error_string;
	}

	/* Assert for static analyser that the function is not NULL */
	assert(REAL_internal_gamemode_error_string != NULL);

	return REAL_internal_gamemode_error_string();
}

/**
 * Redirect to the real libgamemode
 * Allow automatically requesting game mode
 * Also prints errors as they happen.
 */
#ifdef GAMEMODE_AUTO
__attribute__((constructor))
#else
__attribute__((always_inline)) static inline
#endif
int gamemode_request_start(void)
{
	/* Need to load gamemode */
	if (internal_load_libgamemode() < 0) {
#ifdef GAMEMODE_AUTO
		fprintf(stderr, "gamemodeauto: %s\n", gamemode_error_string());
#endif
		return -1;
	}

	/* Assert for static analyser that the function is not NULL */
	assert(REAL_internal_gamemode_request_start != NULL);

	if (REAL_internal_gamemode_request_start() < 0) {
#ifdef GAMEMODE_AUTO
		fprintf(stderr, "gamemodeauto: %s\n", gamemode_error_string());
#endif
		return -1;
	}

	return 0;
}

/* Redirect to the real libgamemode */
#ifdef GAMEMODE_AUTO
__attribute__((destructor))
#else
__attribute__((always_inline)) static inline
#endif
int gamemode_request_end(void)
{
	/* Need to load gamemode */
	if (internal_load_libgamemode() < 0) {
#ifdef GAMEMODE_AUTO
		fprintf(stderr, "gamemodeauto: %s\n", gamemode_error_string());
#endif
		return -1;
	}

	/* Assert for static analyser that the function is not NULL */
	assert(REAL_internal_gamemode_request_end != NULL);

	if (REAL_internal_gamemode_request_end() < 0) {
#ifdef GAMEMODE_AUTO
		fprintf(stderr, "gamemodeauto: %s\n", gamemode_error_string());
#endif
		return -1;
	}

	return 0;
}

/* Redirect to the real libgamemode */
__attribute__((always_inline)) static inline int gamemode_query_status(void)
{
	/* Need to load gamemode */
	if (internal_load_libgamemode() < 0) {
		return -1;
	}

	if (REAL_internal_gamemode_query_status == NULL) {
		snprintf(internal_gamemode_client_error_string,
		         sizeof(internal_gamemode_client_error_string),
		         "gamemode_query_status missing (older host?)");
		return -1;
	}

	return REAL_internal_gamemode_query_status();
}

/* Redirect to the real libgamemode */
__attribute__((always_inline)) static inline int gamemode_request_start_for(pid_t pid)
{
	/* Need to load gamemode */
	if (internal_load_libgamemode() < 0) {
		return -1;
	}

	if (REAL_internal_gamemode_request_start_for == NULL) {
		snprintf(internal_gamemode_client_error_string,
		         sizeof(internal_gamemode_client_error_string),
		         "gamemode_request_start_for missing (older host?)");
		return -1;
	}

	return REAL_internal_gamemode_request_start_for(pid);
}

/* Redirect to the real libgamemode */
__attribute__((always_inline)) static inline int gamemode_request_end_for(pid_t pid)
{
	/* Need to load gamemode */
	if (internal_load_libgamemode() < 0) {
		return -1;
	}

	if (REAL_internal_gamemode_request_end_for == NULL) {
		snprintf(internal_gamemode_client_error_string,
		         sizeof(internal_gamemode_client_error_string),
		         "gamemode_request_end_for missing (older host?)");
		return -1;
	}

	return REAL_internal_gamemode_request_end_for(pid);
}

/* Redirect to the real libgamemode */
__attribute__((always_inline)) static inline int gamemode_query_status_for(pid_t pid)
{
	/* Need to load gamemode */
	if (internal_load_libgamemode() < 0) {
		return -1;
	}

	if (REAL_internal_gamemode_query_status_for == NULL) {
		snprintf(internal_gamemode_client_error_string,
		         sizeof(internal_gamemode_client_error_string),
		         "gamemode_query_status_for missing (older host?)");
		return -1;
	}

	return REAL_internal_gamemode_query_status_for(pid);
}

#endif // CLIENT_GAMEMODE_H