Atlas - SDL_audiodev.c
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[FILE BEGIN]
1/*
2  Simple DirectMedia Layer
3  Copyright (C) 1997-2025 Sam Lantinga <[email protected]>
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#include "SDL_internal.h"
22
23// Get the name of the audio device we use for output
24
25#if defined(SDL_AUDIO_DRIVER_NETBSD) || defined(SDL_AUDIO_DRIVER_OSS)
26
27#include <fcntl.h>
28#include <sys/types.h>
29#include <sys/stat.h>
30#include <unistd.h> // For close()
31
32#include "SDL_audiodev_c.h"
33
34#ifndef SDL_PATH_DEV_DSP
35#if defined(SDL_PLATFORM_NETBSD) || defined(SDL_PLATFORM_OPENBSD)
36#define SDL_PATH_DEV_DSP "/dev/audio"
37#else
38#define SDL_PATH_DEV_DSP "/dev/dsp"
39#endif
40#endif
41#ifndef SDL_PATH_DEV_DSP24
42#define SDL_PATH_DEV_DSP24 "/dev/sound/dsp"
43#endif
44#ifndef SDL_PATH_DEV_AUDIO
45#define SDL_PATH_DEV_AUDIO "/dev/audio"
46#endif
47
48static void test_device(const bool recording, const char *fname, int flags, bool (*test)(int fd))
49{
50    struct stat sb;
51    const int audio_fd = open(fname, flags | O_CLOEXEC, 0);
52    if (audio_fd >= 0) {
53        if ((fstat(audio_fd, &sb) == 0) && (S_ISCHR(sb.st_mode))) {
54            const bool okay = test(audio_fd);
55            close(audio_fd);
56            if (okay) {
57                static size_t dummyhandle = 0;
58                dummyhandle++;
59                SDL_assert(dummyhandle != 0);
60
61                /* Note that spec is NULL; while we are opening the device
62                 * endpoint here, the endpoint does not provide any mix format
63                 * information,  making this information inaccessible at
64                 * enumeration time
65                 */
66                SDL_AddAudioDevice(recording, fname, NULL, (void *)(uintptr_t)dummyhandle);
67            }
68        } else {
69            close(audio_fd);
70        }
71    }
72}
73
74static bool test_stub(int fd)
75{
76    return true;
77}
78
79static void SDL_EnumUnixAudioDevices_Internal(const bool recording, const bool classic, bool (*test)(int))
80{
81    const int flags = recording ? OPEN_FLAGS_INPUT : OPEN_FLAGS_OUTPUT;
82    const char *audiodev;
83    char audiopath[1024];
84
85    if (!test) {
86        test = test_stub;
87    }
88
89    // Figure out what our audio device is
90    audiodev = SDL_getenv("AUDIODEV");
91    if (!audiodev) {
92        if (classic) {
93            audiodev = SDL_PATH_DEV_AUDIO;
94        } else {
95            struct stat sb;
96
97            // Added support for /dev/sound/\* in Linux 2.4
98            if (((stat("/dev/sound", &sb) == 0) && S_ISDIR(sb.st_mode)) && ((stat(SDL_PATH_DEV_DSP24, &sb) == 0) && S_ISCHR(sb.st_mode))) {
99                audiodev = SDL_PATH_DEV_DSP24;
100            } else {
101                audiodev = SDL_PATH_DEV_DSP;
102            }
103        }
104    }
105    test_device(recording, audiodev, flags, test);
106
107    if (SDL_strlen(audiodev) < (sizeof(audiopath) - 3)) {
108        int instance = 0;
109        while (instance <= 64) {
110            (void)SDL_snprintf(audiopath, SDL_arraysize(audiopath),
111                               "%s%d", audiodev, instance);
112            instance++;
113            test_device(recording, audiopath, flags, test);
114        }
115    }
116}
117
118void SDL_EnumUnixAudioDevices(const bool classic, bool (*test)(int))
119{
120    SDL_EnumUnixAudioDevices_Internal(true, classic, test);
121    SDL_EnumUnixAudioDevices_Internal(false, classic, test);
122}
123
124#endif // Audio device selection
125
[FILE END]
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