qapi, audio: Make introspection reflect build configuration more closely

Currently the -audiodev accepts any audiodev type regardless of what is
built in to QEMU. An error only occurs later at runtime when a sound
device tries to use the audio backend.

With this change QEMU will immediately reject -audiodev args that are
not compiled into the binary. The QMP schema will also be introspectable
to identify what is compiled in.

This also helps to avoid compiling code that is not required in the
binary. Note: When building the audiodevs as modules, the patch only
compiles out code for modules that we don't build at all.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
[thuth: Rebase, take sndio and dbus devices into account]
Message-Id: <20230123083957.20349-3-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

4 files changed, 112 insertions, 13 deletions

diff --git a/audio/audio.c b/audio/audio.c
index 6f270c07b7..4290309d18 100644
--- a/audio/audio.c
+++ b/audio/audio.c
@@ -2048,16 +2048,36 @@ void audio_create_pdos(Audiodev *dev)
         break
 
         CASE(NONE, none, );
+#ifdef CONFIG_AUDIO_ALSA
         CASE(ALSA, alsa, Alsa);
+#endif
+#ifdef CONFIG_AUDIO_COREAUDIO
         CASE(COREAUDIO, coreaudio, Coreaudio);
+#endif
+#ifdef CONFIG_DBUS_DISPLAY
         CASE(DBUS, dbus, );
+#endif
+#ifdef CONFIG_AUDIO_DSOUND
         CASE(DSOUND, dsound, );
+#endif
+#ifdef CONFIG_AUDIO_JACK
         CASE(JACK, jack, Jack);
+#endif
+#ifdef CONFIG_AUDIO_OSS
         CASE(OSS, oss, Oss);
+#endif
+#ifdef CONFIG_AUDIO_PA
         CASE(PA, pa, Pa);
+#endif
+#ifdef CONFIG_AUDIO_SDL
         CASE(SDL, sdl, Sdl);
+#endif
+#ifdef CONFIG_AUDIO_SNDIO
         CASE(SNDIO, sndio, );
+#endif
+#ifdef CONFIG_SPICE
         CASE(SPICE, spice, );
+#endif
         CASE(WAV, wav, );
 
     case AUDIODEV_DRIVER__MAX:
diff --git a/audio/audio_legacy.c b/audio/audio_legacy.c
index 18a89ffffb..b848001ff7 100644
--- a/audio/audio_legacy.c
+++ b/audio/audio_legacy.c
@@ -90,6 +90,7 @@ static void get_fmt(const char *env, AudioFormat *dst, bool *has_dst)
 }
 
 
+#if defined(CONFIG_AUDIO_ALSA) || defined(CONFIG_AUDIO_DSOUND)
 static void get_millis_to_usecs(const char *env, uint32_t *dst, bool *has_dst)
 {
     const char *val = getenv(env);
@@ -98,15 +99,20 @@ static void get_millis_to_usecs(const char *env, uint32_t *dst, bool *has_dst)
         *has_dst = true;
     }
 }
+#endif
 
+#if defined(CONFIG_AUDIO_ALSA) || defined(CONFIG_AUDIO_COREAUDIO) || \
+    defined(CONFIG_AUDIO_PA) || defined(CONFIG_AUDIO_SDL) || \
+    defined(CONFIG_AUDIO_DSOUND) || defined(CONFIG_AUDIO_OSS)
 static uint32_t frames_to_usecs(uint32_t frames,
                                 AudiodevPerDirectionOptions *pdo)
 {
     uint32_t freq = pdo->has_frequency ? pdo->frequency : 44100;
     return (frames * 1000000 + freq / 2) / freq;
 }
+#endif
 
-
+#ifdef CONFIG_AUDIO_COREAUDIO
 static void get_frames_to_usecs(const char *env, uint32_t *dst, bool *has_dst,
                                 AudiodevPerDirectionOptions *pdo)
 {
@@ -116,14 +122,19 @@ static void get_frames_to_usecs(const char *env, uint32_t *dst, bool *has_dst,
         *has_dst = true;
     }
 }
+#endif
 
+#if defined(CONFIG_AUDIO_PA) || defined(CONFIG_AUDIO_SDL) || \
+    defined(CONFIG_AUDIO_DSOUND) || defined(CONFIG_AUDIO_OSS)
 static uint32_t samples_to_usecs(uint32_t samples,
                                  AudiodevPerDirectionOptions *pdo)
 {
     uint32_t channels = pdo->has_channels ? pdo->channels : 2;
     return frames_to_usecs(samples / channels, pdo);
 }
+#endif
 
+#if defined(CONFIG_AUDIO_PA) || defined(CONFIG_AUDIO_SDL)
 static void get_samples_to_usecs(const char *env, uint32_t *dst, bool *has_dst,
                                  AudiodevPerDirectionOptions *pdo)
 {
@@ -133,7 +144,9 @@ static void get_samples_to_usecs(const char *env, uint32_t *dst, bool *has_dst,
         *has_dst = true;
     }
 }
+#endif
 
+#if defined(CONFIG_AUDIO_DSOUND) || defined(CONFIG_AUDIO_OSS)
 static uint32_t bytes_to_usecs(uint32_t bytes, AudiodevPerDirectionOptions *pdo)
 {
     AudioFormat fmt = pdo->has_format ? pdo->format : AUDIO_FORMAT_S16;
@@ -150,8 +163,11 @@ static void get_bytes_to_usecs(const char *env, uint32_t *dst, bool *has_dst,
         *has_dst = true;
     }
 }
+#endif
 
 /* backend specific functions */
+
+#ifdef CONFIG_AUDIO_ALSA
 /* ALSA */
 static void handle_alsa_per_direction(
     AudiodevAlsaPerDirectionOptions *apdo, const char *prefix)
@@ -197,7 +213,9 @@ static void handle_alsa(Audiodev *dev)
     get_millis_to_usecs("QEMU_ALSA_THRESHOLD",
                         &aopt->threshold, &aopt->has_threshold);
 }
+#endif
 
+#ifdef CONFIG_AUDIO_COREAUDIO
 /* coreaudio */
 static void handle_coreaudio(Audiodev *dev)
 {
@@ -210,7 +228,9 @@ static void handle_coreaudio(Audiodev *dev)
             &dev->u.coreaudio.out->buffer_count,
             &dev->u.coreaudio.out->has_buffer_count);
 }
+#endif
 
+#ifdef CONFIG_AUDIO_DSOUND
 /* dsound */
 static void handle_dsound(Audiodev *dev)
 {
@@ -225,7 +245,9 @@ static void handle_dsound(Audiodev *dev)
                        &dev->u.dsound.in->has_buffer_length,
                        dev->u.dsound.in);
 }
+#endif
 
+#ifdef CONFIG_AUDIO_OSS
 /* OSS */
 static void handle_oss_per_direction(
     AudiodevOssPerDirectionOptions *opdo, const char *try_poll_env,
@@ -253,7 +275,9 @@ static void handle_oss(Audiodev *dev)
     get_bool("QEMU_OSS_EXCLUSIVE", &oopt->exclusive, &oopt->has_exclusive);
     get_int("QEMU_OSS_POLICY", &oopt->dsp_policy, &oopt->has_dsp_policy);
 }
+#endif
 
+#ifdef CONFIG_AUDIO_PA
 /* pulseaudio */
 static void handle_pa_per_direction(
     AudiodevPaPerDirectionOptions *ppdo, const char *env)
@@ -277,7 +301,9 @@ static void handle_pa(Audiodev *dev)
 
     get_str("QEMU_PA_SERVER", &dev->u.pa.server);
 }
+#endif
 
+#ifdef CONFIG_AUDIO_SDL
 /* SDL */
 static void handle_sdl(Audiodev *dev)
 {
@@ -286,6 +312,7 @@ static void handle_sdl(Audiodev *dev)
         &dev->u.sdl.out->has_buffer_length,
         qapi_AudiodevSdlPerDirectionOptions_base(dev->u.sdl.out));
 }
+#endif
 
 /* wav */
 static void handle_wav(Audiodev *dev)
@@ -345,29 +372,41 @@ static AudiodevListEntry *legacy_opt(const char *drvname)
     }
 
     switch (e->dev->driver) {
+#ifdef CONFIG_AUDIO_ALSA
     case AUDIODEV_DRIVER_ALSA:
         handle_alsa(e->dev);
         break;
+#endif
 
+#ifdef CONFIG_AUDIO_COREAUDIO
     case AUDIODEV_DRIVER_COREAUDIO:
         handle_coreaudio(e->dev);
         break;
+#endif
 
+#ifdef CONFIG_AUDIO_DSOUND
     case AUDIODEV_DRIVER_DSOUND:
         handle_dsound(e->dev);
         break;
+#endif
 
+#ifdef CONFIG_AUDIO_OSS
     case AUDIODEV_DRIVER_OSS:
         handle_oss(e->dev);
         break;
+#endif
 
+#ifdef CONFIG_AUDIO_PA
     case AUDIODEV_DRIVER_PA:
         handle_pa(e->dev);
         break;
+#endif
 
+#ifdef CONFIG_AUDIO_SDL
     case AUDIODEV_DRIVER_SDL:
         handle_sdl(e->dev);
         break;
+#endif
 
     case AUDIODEV_DRIVER_WAV:
         handle_wav(e->dev);
diff --git a/audio/audio_template.h b/audio/audio_template.h
index 720a32e57e..42b4712acb 100644
--- a/audio/audio_template.h
+++ b/audio/audio_template.h
@@ -326,27 +326,47 @@ AudiodevPerDirectionOptions *glue(audio_get_pdo_, TYPE)(Audiodev *dev)
     switch (dev->driver) {
     case AUDIODEV_DRIVER_NONE:
         return dev->u.none.TYPE;
+#ifdef CONFIG_AUDIO_ALSA
     case AUDIODEV_DRIVER_ALSA:
         return qapi_AudiodevAlsaPerDirectionOptions_base(dev->u.alsa.TYPE);
+#endif
+#ifdef CONFIG_AUDIO_COREAUDIO
     case AUDIODEV_DRIVER_COREAUDIO:
         return qapi_AudiodevCoreaudioPerDirectionOptions_base(
             dev->u.coreaudio.TYPE);
+#endif
+#ifdef CONFIG_DBUS_DISPLAY
     case AUDIODEV_DRIVER_DBUS:
         return dev->u.dbus.TYPE;
+#endif
+#ifdef CONFIG_AUDIO_DSOUND
     case AUDIODEV_DRIVER_DSOUND:
         return dev->u.dsound.TYPE;
+#endif
+#ifdef CONFIG_AUDIO_JACK
     case AUDIODEV_DRIVER_JACK:
         return qapi_AudiodevJackPerDirectionOptions_base(dev->u.jack.TYPE);
+#endif
+#ifdef CONFIG_AUDIO_OSS
     case AUDIODEV_DRIVER_OSS:
         return qapi_AudiodevOssPerDirectionOptions_base(dev->u.oss.TYPE);
+#endif
+#ifdef CONFIG_AUDIO_PA
     case AUDIODEV_DRIVER_PA:
         return qapi_AudiodevPaPerDirectionOptions_base(dev->u.pa.TYPE);
+#endif
+#ifdef CONFIG_AUDIO_SDL
     case AUDIODEV_DRIVER_SDL:
         return qapi_AudiodevSdlPerDirectionOptions_base(dev->u.sdl.TYPE);
+#endif
+#ifdef CONFIG_AUDIO_SNDIO
     case AUDIODEV_DRIVER_SNDIO:
         return dev->u.sndio.TYPE;
+#endif
+#ifdef CONFIG_SPICE
     case AUDIODEV_DRIVER_SPICE:
         return dev->u.spice.TYPE;
+#endif
     case AUDIODEV_DRIVER_WAV:
         return dev->u.wav.TYPE;
 
diff --git a/qapi/audio.json b/qapi/audio.json
index c7aafa2763..4e54c00f51 100644
--- a/qapi/audio.json
+++ b/qapi/audio.json
@@ -408,8 +408,18 @@
 # Since: 4.0
 ##
 { 'enum': 'AudiodevDriver',
-  'data': [ 'none', 'alsa', 'coreaudio', 'dbus', 'dsound', 'jack', 'oss', 'pa',
-            'sdl', 'sndio', 'spice', 'wav' ] }
+  'data': [ 'none',
+            { 'name': 'alsa', 'if': 'CONFIG_AUDIO_ALSA' },
+            { 'name': 'coreaudio', 'if': 'CONFIG_AUDIO_COREAUDIO' },
+            { 'name': 'dbus', 'if': 'CONFIG_DBUS_DISPLAY' },
+            { 'name': 'dsound', 'if': 'CONFIG_AUDIO_DSOUND' },
+            { 'name': 'jack', 'if': 'CONFIG_AUDIO_JACK' },
+            { 'name': 'oss', 'if': 'CONFIG_AUDIO_OSS' },
+            { 'name': 'pa', 'if': 'CONFIG_AUDIO_PA' },
+            { 'name': 'sdl', 'if': 'CONFIG_AUDIO_SDL' },
+            { 'name': 'sndio', 'if': 'CONFIG_AUDIO_SNDIO' },
+            { 'name': 'spice', 'if': 'CONFIG_SPICE' },
+            'wav' ] }
 
 ##
 # @Audiodev:
@@ -432,16 +442,26 @@
   'discriminator': 'driver',
   'data': {
     'none':      'AudiodevGenericOptions',
-    'alsa':      'AudiodevAlsaOptions',
-    'coreaudio': 'AudiodevCoreaudioOptions',
-    'dbus':      'AudiodevGenericOptions',
-    'dsound':    'AudiodevDsoundOptions',
-    'jack':      'AudiodevJackOptions',
-    'oss':       'AudiodevOssOptions',
-    'pa':        'AudiodevPaOptions',
-    'sdl':       'AudiodevSdlOptions',
-    'sndio':     'AudiodevSndioOptions',
-    'spice':     'AudiodevGenericOptions',
+    'alsa':      { 'type': 'AudiodevAlsaOptions',
+                   'if': 'CONFIG_AUDIO_ALSA' },
+    'coreaudio': { 'type': 'AudiodevCoreaudioOptions',
+                   'if': 'CONFIG_AUDIO_COREAUDIO' },
+    'dbus':      { 'type': 'AudiodevGenericOptions',
+                   'if': 'CONFIG_DBUS_DISPLAY' },
+    'dsound':    { 'type': 'AudiodevDsoundOptions',
+                   'if': 'CONFIG_AUDIO_DSOUND' },
+    'jack':      { 'type': 'AudiodevJackOptions',
+                   'if': 'CONFIG_AUDIO_JACK' },
+    'oss':       { 'type': 'AudiodevOssOptions',
+                   'if': 'CONFIG_AUDIO_OSS' },
+    'pa':        { 'type': 'AudiodevPaOptions',
+                   'if': 'CONFIG_AUDIO_PA' },
+    'sdl':       { 'type': 'AudiodevSdlOptions',
+                   'if': 'CONFIG_AUDIO_SDL' },
+    'sndio':     { 'type': 'AudiodevSndioOptions',
+                   'if': 'CONFIG_AUDIO_SNDIO' },
+    'spice':     { 'type': 'AudiodevGenericOptions',
+                   'if': 'CONFIG_SPICE' },
     'wav':       'AudiodevWavOptions' } }
 
 ##