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SDL_audiodev.c (3792B)

      1 /*
      2   Simple DirectMedia Layer
      3   Copyright (C) 1997-2020 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 #include "../SDL_internal.h"
     22 
     23 /* Get the name of the audio device we use for output */
     24 
     25 #if SDL_AUDIO_DRIVER_NETBSD || SDL_AUDIO_DRIVER_OSS || SDL_AUDIO_DRIVER_SUNAUDIO
     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_stdinc.h"
     33 #include "SDL_audiodev_c.h"
     34 
     35 #ifndef _PATH_DEV_DSP
     36 #if defined(__NETBSD__) || defined(__OPENBSD__)
     37 #define _PATH_DEV_DSP  "/dev/audio"
     38 #else
     39 #define _PATH_DEV_DSP  "/dev/dsp"
     40 #endif
     41 #endif
     42 #ifndef _PATH_DEV_DSP24
     43 #define _PATH_DEV_DSP24 "/dev/sound/dsp"
     44 #endif
     45 #ifndef _PATH_DEV_AUDIO
     46 #define _PATH_DEV_AUDIO "/dev/audio"
     47 #endif
     48 
     49 static void
     50 test_device(const int iscapture, const char *fname, int flags, int (*test) (int fd))
     51 {
     52     struct stat sb;
     53     if ((stat(fname, &sb) == 0) && (S_ISCHR(sb.st_mode))) {
     54         const int audio_fd = open(fname, flags, 0);
     55         if (audio_fd >= 0) {
     56             const int okay = test(audio_fd);
     57             close(audio_fd);
     58             if (okay) {
     59                 static size_t dummyhandle = 0;
     60                 dummyhandle++;
     61                 SDL_assert(dummyhandle != 0);
     62                 SDL_AddAudioDevice(iscapture, fname, (void *) dummyhandle);
     63             }
     64         }
     65     }
     66 }
     67 
     68 static int
     69 test_stub(int fd)
     70 {
     71     return 1;
     72 }
     73 
     74 static void
     75 SDL_EnumUnixAudioDevices_Internal(const int iscapture, const int classic, int (*test)(int))
     76 {
     77     const int flags = iscapture ? OPEN_FLAGS_INPUT : OPEN_FLAGS_OUTPUT;
     78     const char *audiodev;
     79     char audiopath[1024];
     80 
     81     if (test == NULL)
     82         test = test_stub;
     83 
     84     /* Figure out what our audio device is */
     85     if (((audiodev = SDL_getenv("SDL_PATH_DSP")) == NULL) &&
     86         ((audiodev = SDL_getenv("AUDIODEV")) == NULL)) {
     87         if (classic) {
     88             audiodev = _PATH_DEV_AUDIO;
     89         } else {
     90             struct stat sb;
     91 
     92             /* Added support for /dev/sound/\* in Linux 2.4 */
     93             if (((stat("/dev/sound", &sb) == 0) && S_ISDIR(sb.st_mode))
     94                 && ((stat(_PATH_DEV_DSP24, &sb) == 0)
     95                     && S_ISCHR(sb.st_mode))) {
     96                 audiodev = _PATH_DEV_DSP24;
     97             } else {
     98                 audiodev = _PATH_DEV_DSP;
     99             }
    100         }
    101     }
    102     test_device(iscapture, audiodev, flags, test);
    103 
    104     if (SDL_strlen(audiodev) < (sizeof(audiopath) - 3)) {
    105         int instance = 0;
    106         while (instance <= 64) {
    107             SDL_snprintf(audiopath, SDL_arraysize(audiopath),
    108                          "%s%d", audiodev, instance);
    109             instance++;
    110             test_device(iscapture, audiopath, flags, test);
    111         }
    112     }
    113 }
    114 
    115 void
    116 SDL_EnumUnixAudioDevices(const int classic, int (*test)(int))
    117 {
    118     SDL_EnumUnixAudioDevices_Internal(SDL_TRUE, classic, test);
    119     SDL_EnumUnixAudioDevices_Internal(SDL_FALSE, classic, test);
    120 }
    121 
    122 #endif /* Audio driver selection */
    123 
    124 /* vi: set ts=4 sw=4 expandtab: */