audio/audio_legacy.c - qemu - Git at Google

 /*
  * QEMU Audio subsystem: legacy configuration handling
  *
  * Copyright (c) 2015-2019 Zoltán Kővágó <DirtY.iCE.hu@gmail.com>
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
 #include "qemu/osdep.h"
 #include "audio.h"
 #include "audio_int.h"
 #include "qemu/cutils.h"
 #include "qemu/timer.h"
 #include "qapi/error.h"
 #include "qapi/qapi-visit-audio.h"
 #include "qapi/visitor-impl.h"

 #define AUDIO_CAP "audio-legacy"
 #include "audio_int.h"

 static uint32_t toui32(const char *str)
 {
     unsigned long long ret;
     if (parse_uint_full(str, &ret, 10) || ret > UINT32_MAX) {
         dolog("Invalid integer value `%s'\n", str);
         exit(1);
     }
     return ret;
 }

 /* helper functions to convert env variables */
 static void get_bool(const char *env, bool *dst, bool *has_dst)
 {
     const char *val = getenv(env);
     if (val) {
         *dst = toui32(val) != 0;
         *has_dst = true;
     }
 }

 static void get_int(const char *env, uint32_t *dst, bool *has_dst)
 {
     const char *val = getenv(env);
     if (val) {
         *dst = toui32(val);
         *has_dst = true;
     }
 }

 static void get_str(const char *env, char **dst, bool *has_dst)
 {
     const char *val = getenv(env);
     if (val) {
         if (*has_dst) {
             g_free(*dst);
         }
         *dst = g_strdup(val);
         *has_dst = true;
     }
 }

 static void get_fmt(const char *env, AudioFormat *dst, bool *has_dst)
 {
     const char *val = getenv(env);
     if (val) {
         size_t i;
         for (i = 0; AudioFormat_lookup.size; ++i) {
             if (strcasecmp(val, AudioFormat_lookup.array[i]) == 0) {
                 *dst = i;
                 *has_dst = true;
                 return;
             }
         }

         dolog("Invalid audio format `%s'\n", val);
         exit(1);
     }
 }


 static void get_millis_to_usecs(const char *env, uint32_t *dst, bool *has_dst)
 {
     const char *val = getenv(env);
     if (val) {
         *dst = toui32(val) * 1000;
         *has_dst = true;
     }
 }

 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;
 }


 static void get_frames_to_usecs(const char *env, uint32_t *dst, bool *has_dst,
                                 AudiodevPerDirectionOptions *pdo)
 {
     const char *val = getenv(env);
     if (val) {
         *dst = frames_to_usecs(toui32(val), pdo);
         *has_dst = true;
     }
 }

 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);
 }

 static void get_samples_to_usecs(const char *env, uint32_t *dst, bool *has_dst,
                                  AudiodevPerDirectionOptions *pdo)
 {
     const char *val = getenv(env);
     if (val) {
         *dst = samples_to_usecs(toui32(val), pdo);
         *has_dst = true;
     }
 }

 static uint32_t bytes_to_usecs(uint32_t bytes, AudiodevPerDirectionOptions *pdo)
 {
     AudioFormat fmt = pdo->has_format ? pdo->format : AUDIO_FORMAT_S16;
     uint32_t bytes_per_sample = audioformat_bytes_per_sample(fmt);
     return samples_to_usecs(bytes / bytes_per_sample, pdo);
 }

 static void get_bytes_to_usecs(const char *env, uint32_t *dst, bool *has_dst,
                                AudiodevPerDirectionOptions *pdo)
 {
     const char *val = getenv(env);
     if (val) {
         *dst = bytes_to_usecs(toui32(val), pdo);
         *has_dst = true;
     }
 }

 /* backend specific functions */
 /* ALSA */
 static void handle_alsa_per_direction(
     AudiodevAlsaPerDirectionOptions *apdo, const char *prefix)
 {
     char buf[64];
     size_t len = strlen(prefix);
     bool size_in_usecs = false;
     bool dummy;

     memcpy(buf, prefix, len);
     strcpy(buf + len, "TRY_POLL");
     get_bool(buf, &apdo->try_poll, &apdo->has_try_poll);

     strcpy(buf + len, "DEV");
     get_str(buf, &apdo->dev, &apdo->has_dev);

     strcpy(buf + len, "SIZE_IN_USEC");
     get_bool(buf, &size_in_usecs, &dummy);

     strcpy(buf + len, "PERIOD_SIZE");
     get_int(buf, &apdo->period_length, &apdo->has_period_length);
     if (apdo->has_period_length && !size_in_usecs) {
         apdo->period_length = frames_to_usecs(
             apdo->period_length,
             qapi_AudiodevAlsaPerDirectionOptions_base(apdo));
     }

     strcpy(buf + len, "BUFFER_SIZE");
     get_int(buf, &apdo->buffer_length, &apdo->has_buffer_length);
     if (apdo->has_buffer_length && !size_in_usecs) {
         apdo->buffer_length = frames_to_usecs(
             apdo->buffer_length,
             qapi_AudiodevAlsaPerDirectionOptions_base(apdo));
     }
 }

 static void handle_alsa(Audiodev *dev)
 {
     AudiodevAlsaOptions *aopt = &dev->u.alsa;
     handle_alsa_per_direction(aopt->in, "QEMU_ALSA_ADC_");
     handle_alsa_per_direction(aopt->out, "QEMU_ALSA_DAC_");

     get_millis_to_usecs("QEMU_ALSA_THRESHOLD",
                         &aopt->threshold, &aopt->has_threshold);
 }

 /* coreaudio */
 static void handle_coreaudio(Audiodev *dev)
 {
     get_frames_to_usecs(
         "QEMU_COREAUDIO_BUFFER_SIZE",
         &dev->u.coreaudio.out->buffer_length,
         &dev->u.coreaudio.out->has_buffer_length,
         qapi_AudiodevCoreaudioPerDirectionOptions_base(dev->u.coreaudio.out));
     get_int("QEMU_COREAUDIO_BUFFER_COUNT",
             &dev->u.coreaudio.out->buffer_count,
             &dev->u.coreaudio.out->has_buffer_count);
 }

 /* dsound */
 static void handle_dsound(Audiodev *dev)
 {
     get_millis_to_usecs("QEMU_DSOUND_LATENCY_MILLIS",
                         &dev->u.dsound.latency, &dev->u.dsound.has_latency);
     get_bytes_to_usecs("QEMU_DSOUND_BUFSIZE_OUT",
                        &dev->u.dsound.out->buffer_length,
                        &dev->u.dsound.out->has_buffer_length,
                        dev->u.dsound.out);
     get_bytes_to_usecs("QEMU_DSOUND_BUFSIZE_IN",
                        &dev->u.dsound.in->buffer_length,
                        &dev->u.dsound.in->has_buffer_length,
                        dev->u.dsound.in);
 }

 /* OSS */
 static void handle_oss_per_direction(
     AudiodevOssPerDirectionOptions *opdo, const char *try_poll_env,
     const char *dev_env)
 {
     get_bool(try_poll_env, &opdo->try_poll, &opdo->has_try_poll);
     get_str(dev_env, &opdo->dev, &opdo->has_dev);

     get_bytes_to_usecs("QEMU_OSS_FRAGSIZE",
                        &opdo->buffer_length, &opdo->has_buffer_length,
                        qapi_AudiodevOssPerDirectionOptions_base(opdo));
     get_int("QEMU_OSS_NFRAGS", &opdo->buffer_count,
             &opdo->has_buffer_count);
 }

 static void handle_oss(Audiodev *dev)
 {
     AudiodevOssOptions *oopt = &dev->u.oss;
     handle_oss_per_direction(oopt->in, "QEMU_AUDIO_ADC_TRY_POLL",
                              "QEMU_OSS_ADC_DEV");
     handle_oss_per_direction(oopt->out, "QEMU_AUDIO_DAC_TRY_POLL",
                              "QEMU_OSS_DAC_DEV");

     get_bool("QEMU_OSS_MMAP", &oopt->try_mmap, &oopt->has_try_mmap);
     get_bool("QEMU_OSS_EXCLUSIVE", &oopt->exclusive, &oopt->has_exclusive);
     get_int("QEMU_OSS_POLICY", &oopt->dsp_policy, &oopt->has_dsp_policy);
 }

 /* pulseaudio */
 static void handle_pa_per_direction(
     AudiodevPaPerDirectionOptions *ppdo, const char *env)
 {
     get_str(env, &ppdo->name, &ppdo->has_name);
 }

 static void handle_pa(Audiodev *dev)
 {
     handle_pa_per_direction(dev->u.pa.in, "QEMU_PA_SOURCE");
     handle_pa_per_direction(dev->u.pa.out, "QEMU_PA_SINK");

     get_samples_to_usecs(
         "QEMU_PA_SAMPLES", &dev->u.pa.in->buffer_length,
         &dev->u.pa.in->has_buffer_length,
         qapi_AudiodevPaPerDirectionOptions_base(dev->u.pa.in));
     get_samples_to_usecs(
         "QEMU_PA_SAMPLES", &dev->u.pa.out->buffer_length,
         &dev->u.pa.out->has_buffer_length,
         qapi_AudiodevPaPerDirectionOptions_base(dev->u.pa.out));

     get_str("QEMU_PA_SERVER", &dev->u.pa.server, &dev->u.pa.has_server);
 }

 /* SDL */
 static void handle_sdl(Audiodev *dev)
 {
     /* SDL is output only */
     get_samples_to_usecs("QEMU_SDL_SAMPLES", &dev->u.sdl.out->buffer_length,
         &dev->u.sdl.out->has_buffer_length,
         qapi_AudiodevSdlPerDirectionOptions_base(dev->u.sdl.out));
 }

 /* wav */
 static void handle_wav(Audiodev *dev)
 {
     get_int("QEMU_WAV_FREQUENCY",
             &dev->u.wav.out->frequency, &dev->u.wav.out->has_frequency);
     get_fmt("QEMU_WAV_FORMAT", &dev->u.wav.out->format,
             &dev->u.wav.out->has_format);
     get_int("QEMU_WAV_DAC_FIXED_CHANNELS",
             &dev->u.wav.out->channels, &dev->u.wav.out->has_channels);
     get_str("QEMU_WAV_PATH", &dev->u.wav.path, &dev->u.wav.has_path);
 }

 /* general */
 static void handle_per_direction(
     AudiodevPerDirectionOptions *pdo, const char *prefix)
 {
     char buf[64];
     size_t len = strlen(prefix);

     memcpy(buf, prefix, len);
     strcpy(buf + len, "FIXED_SETTINGS");
     get_bool(buf, &pdo->fixed_settings, &pdo->has_fixed_settings);

     strcpy(buf + len, "FIXED_FREQ");
     get_int(buf, &pdo->frequency, &pdo->has_frequency);

     strcpy(buf + len, "FIXED_FMT");
     get_fmt(buf, &pdo->format, &pdo->has_format);

     strcpy(buf + len, "FIXED_CHANNELS");
     get_int(buf, &pdo->channels, &pdo->has_channels);

     strcpy(buf + len, "VOICES");
     get_int(buf, &pdo->voices, &pdo->has_voices);
 }

 static AudiodevListEntry *legacy_opt(const char *drvname)
 {
     AudiodevListEntry *e = g_malloc0(sizeof(AudiodevListEntry));
     e->dev = g_malloc0(sizeof(Audiodev));
     e->dev->id = g_strdup(drvname);
     e->dev->driver = qapi_enum_parse(
         &AudiodevDriver_lookup, drvname, -1, &error_abort);

     audio_create_pdos(e->dev);

     handle_per_direction(audio_get_pdo_in(e->dev), "QEMU_AUDIO_ADC_");
     handle_per_direction(audio_get_pdo_out(e->dev), "QEMU_AUDIO_DAC_");

     /* Original description: Timer period in HZ (0 - use lowest possible) */
     get_int("QEMU_AUDIO_TIMER_PERIOD",
             &e->dev->timer_period, &e->dev->has_timer_period);
     if (e->dev->has_timer_period && e->dev->timer_period) {
         e->dev->timer_period = NANOSECONDS_PER_SECOND / 1000 /
                                e->dev->timer_period;
     }

     switch (e->dev->driver) {
     case AUDIODEV_DRIVER_ALSA:
         handle_alsa(e->dev);
         break;

     case AUDIODEV_DRIVER_COREAUDIO:
         handle_coreaudio(e->dev);
         break;

     case AUDIODEV_DRIVER_DSOUND:
         handle_dsound(e->dev);
         break;

     case AUDIODEV_DRIVER_OSS:
         handle_oss(e->dev);
         break;

     case AUDIODEV_DRIVER_PA:
         handle_pa(e->dev);
         break;

     case AUDIODEV_DRIVER_SDL:
         handle_sdl(e->dev);
         break;

     case AUDIODEV_DRIVER_WAV:
         handle_wav(e->dev);
         break;

     default:
         break;
     }

     return e;
 }

 AudiodevListHead audio_handle_legacy_opts(void)
 {
     const char *drvname = getenv("QEMU_AUDIO_DRV");
     AudiodevListHead head = QSIMPLEQ_HEAD_INITIALIZER(head);

     if (drvname) {
         AudiodevListEntry *e;
         audio_driver *driver = audio_driver_lookup(drvname);
         if (!driver) {
             dolog("Unknown audio driver `%s'\n", drvname);
             exit(1);
         }
         e = legacy_opt(drvname);
         QSIMPLEQ_INSERT_TAIL(&head, e, next);
     } else {
         for (int i = 0; audio_prio_list[i]; i++) {
             audio_driver *driver = audio_driver_lookup(audio_prio_list[i]);
             if (driver && driver->can_be_default) {
                 AudiodevListEntry *e = legacy_opt(driver->name);
                 QSIMPLEQ_INSERT_TAIL(&head, e, next);
             }
         }
         if (QSIMPLEQ_EMPTY(&head)) {
             dolog("Internal error: no default audio driver available\n");
             exit(1);
         }
     }

     return head;
 }

 /* visitor to print -audiodev option */
 typedef struct {
     Visitor visitor;

     bool comma;
     GList *path;
 } LegacyPrintVisitor;

 static bool lv_start_struct(Visitor *v, const char *name, void **obj,
                             size_t size, Error **errp)
 {
     LegacyPrintVisitor *lv = (LegacyPrintVisitor *) v;
     lv->path = g_list_append(lv->path, g_strdup(name));
     return true;
 }

 static void lv_end_struct(Visitor *v, void **obj)
 {
     LegacyPrintVisitor *lv = (LegacyPrintVisitor *) v;
     lv->path = g_list_delete_link(lv->path, g_list_last(lv->path));
 }

 static void lv_print_key(Visitor *v, const char *name)
 {
     GList *e;
     LegacyPrintVisitor *lv = (LegacyPrintVisitor *) v;
     if (lv->comma) {
         putchar(',');
     } else {
         lv->comma = true;
     }

     for (e = lv->path; e; e = e->next) {
         if (e->data) {
             printf("%s.", (const char *) e->data);
         }
     }

     printf("%s=", name);
 }

 static bool lv_type_int64(Visitor *v, const char *name, int64_t *obj,
                           Error **errp)
 {
     lv_print_key(v, name);
     printf("%" PRIi64, *obj);
     return true;
 }

 static bool lv_type_uint64(Visitor *v, const char *name, uint64_t *obj,
                            Error **errp)
 {
     lv_print_key(v, name);
     printf("%" PRIu64, *obj);
     return true;
 }

 static bool lv_type_bool(Visitor *v, const char *name, bool *obj, Error **errp)
 {
     lv_print_key(v, name);
     printf("%s", *obj ? "on" : "off");
     return true;
 }

 static bool lv_type_str(Visitor *v, const char *name, char **obj, Error **errp)
 {
     const char *str = *obj;
     lv_print_key(v, name);

     while (*str) {
         if (*str == ',') {
             putchar(',');
         }
         putchar(*str++);
     }
     return true;
 }

 static void lv_complete(Visitor *v, void *opaque)
 {
     LegacyPrintVisitor *lv = (LegacyPrintVisitor *) v;
     assert(lv->path == NULL);
 }

 static void lv_free(Visitor *v)
 {
     LegacyPrintVisitor *lv = (LegacyPrintVisitor *) v;

     g_list_free_full(lv->path, g_free);
     g_free(lv);
 }

 static Visitor *legacy_visitor_new(void)
 {
     LegacyPrintVisitor *lv = g_malloc0(sizeof(LegacyPrintVisitor));

     lv->visitor.start_struct = lv_start_struct;
     lv->visitor.end_struct = lv_end_struct;
     /* lists not supported */
     lv->visitor.type_int64 = lv_type_int64;
     lv->visitor.type_uint64 = lv_type_uint64;
     lv->visitor.type_bool = lv_type_bool;
     lv->visitor.type_str = lv_type_str;

     lv->visitor.type = VISITOR_OUTPUT;
     lv->visitor.complete = lv_complete;
     lv->visitor.free = lv_free;

     return &lv->visitor;
 }

 void audio_legacy_help(void)
 {
     AudiodevListHead head;
     AudiodevListEntry *e;

     printf("Environment variable based configuration deprecated.\n");
     printf("Please use the new -audiodev option.\n");

     head = audio_handle_legacy_opts();
     printf("\nEquivalent -audiodev to your current environment variables:\n");
     if (!getenv("QEMU_AUDIO_DRV")) {
         printf("(Since you didn't specify QEMU_AUDIO_DRV, I'll list all "
                "possibilities)\n");
     }

     QSIMPLEQ_FOREACH(e, &head, next) {
         Visitor *v;
         Audiodev *dev = e->dev;
         printf("-audiodev ");

         v = legacy_visitor_new();
         visit_type_Audiodev(v, NULL, &dev, &error_abort);
         visit_free(v);

         printf("\n");
     }
     audio_free_audiodev_list(&head);
 }
	/*
	* QEMU Audio subsystem: legacy configuration handling
	*
	* Copyright (c) 2015-2019 Zoltán Kővágó <DirtY.iCE.hu@gmail.com>
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	*/
	#include "qemu/osdep.h"
	#include "audio.h"
	#include "audio_int.h"
	#include "qemu/cutils.h"
	#include "qemu/timer.h"
	#include "qapi/error.h"
	#include "qapi/qapi-visit-audio.h"
	#include "qapi/visitor-impl.h"

	#define AUDIO_CAP "audio-legacy"
	#include "audio_int.h"

	static uint32_t toui32(const char *str)
	{
	unsigned long long ret;
	if (parse_uint_full(str, &ret, 10) \|\| ret > UINT32_MAX) {
	dolog("Invalid integer value `%s'\n", str);
	exit(1);
	}
	return ret;
	}

	/* helper functions to convert env variables */
	static void get_bool(const char env, bool dst, bool *has_dst)
	{
	const char *val = getenv(env);
	if (val) {
	*dst = toui32(val) != 0;
	*has_dst = true;
	}
	}

	static void get_int(const char env, uint32_t dst, bool *has_dst)
	{
	const char *val = getenv(env);
	if (val) {
	*dst = toui32(val);
	*has_dst = true;
	}
	}

	static void get_str(const char env, char dst, bool has_dst)
	{
	const char *val = getenv(env);
	if (val) {
	if (*has_dst) {
	g_free(*dst);
	}
	*dst = g_strdup(val);
	*has_dst = true;
	}
	}

	static void get_fmt(const char env, AudioFormat dst, bool *has_dst)
	{
	const char *val = getenv(env);
	if (val) {
	size_t i;
	for (i = 0; AudioFormat_lookup.size; ++i) {
	if (strcasecmp(val, AudioFormat_lookup.array[i]) == 0) {
	*dst = i;
	*has_dst = true;
	return;
	}
	}

	dolog("Invalid audio format `%s'\n", val);
	exit(1);
	}
	}


	static void get_millis_to_usecs(const char env, uint32_t dst, bool *has_dst)
	{
	const char *val = getenv(env);
	if (val) {
	dst = toui32(val) 1000;
	*has_dst = true;
	}
	}

	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;
	}


	static void get_frames_to_usecs(const char env, uint32_t dst, bool *has_dst,
	AudiodevPerDirectionOptions *pdo)
	{
	const char *val = getenv(env);
	if (val) {
	*dst = frames_to_usecs(toui32(val), pdo);
	*has_dst = true;
	}
	}

	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);
	}

	static void get_samples_to_usecs(const char env, uint32_t dst, bool *has_dst,
	AudiodevPerDirectionOptions *pdo)
	{
	const char *val = getenv(env);
	if (val) {
	*dst = samples_to_usecs(toui32(val), pdo);
	*has_dst = true;
	}
	}

	static uint32_t bytes_to_usecs(uint32_t bytes, AudiodevPerDirectionOptions *pdo)
	{
	AudioFormat fmt = pdo->has_format ? pdo->format : AUDIO_FORMAT_S16;
	uint32_t bytes_per_sample = audioformat_bytes_per_sample(fmt);
	return samples_to_usecs(bytes / bytes_per_sample, pdo);
	}

	static void get_bytes_to_usecs(const char env, uint32_t dst, bool *has_dst,
	AudiodevPerDirectionOptions *pdo)
	{
	const char *val = getenv(env);
	if (val) {
	*dst = bytes_to_usecs(toui32(val), pdo);
	*has_dst = true;
	}
	}

	/* backend specific functions */
	/* ALSA */
	static void handle_alsa_per_direction(
	AudiodevAlsaPerDirectionOptions apdo, const char prefix)
	{
	char buf[64];
	size_t len = strlen(prefix);
	bool size_in_usecs = false;
	bool dummy;

	memcpy(buf, prefix, len);
	strcpy(buf + len, "TRY_POLL");
	get_bool(buf, &apdo->try_poll, &apdo->has_try_poll);

	strcpy(buf + len, "DEV");
	get_str(buf, &apdo->dev, &apdo->has_dev);

	strcpy(buf + len, "SIZE_IN_USEC");
	get_bool(buf, &size_in_usecs, &dummy);

	strcpy(buf + len, "PERIOD_SIZE");
	get_int(buf, &apdo->period_length, &apdo->has_period_length);
	if (apdo->has_period_length && !size_in_usecs) {
	apdo->period_length = frames_to_usecs(
	apdo->period_length,
	qapi_AudiodevAlsaPerDirectionOptions_base(apdo));
	}

	strcpy(buf + len, "BUFFER_SIZE");
	get_int(buf, &apdo->buffer_length, &apdo->has_buffer_length);
	if (apdo->has_buffer_length && !size_in_usecs) {
	apdo->buffer_length = frames_to_usecs(
	apdo->buffer_length,
	qapi_AudiodevAlsaPerDirectionOptions_base(apdo));
	}
	}

	static void handle_alsa(Audiodev *dev)
	{
	AudiodevAlsaOptions *aopt = &dev->u.alsa;
	handle_alsa_per_direction(aopt->in, "QEMU_ALSA_ADC_");
	handle_alsa_per_direction(aopt->out, "QEMU_ALSA_DAC_");

	get_millis_to_usecs("QEMU_ALSA_THRESHOLD",
	&aopt->threshold, &aopt->has_threshold);
	}

	/* coreaudio */
	static void handle_coreaudio(Audiodev *dev)
	{
	get_frames_to_usecs(
	"QEMU_COREAUDIO_BUFFER_SIZE",
	&dev->u.coreaudio.out->buffer_length,
	&dev->u.coreaudio.out->has_buffer_length,
	qapi_AudiodevCoreaudioPerDirectionOptions_base(dev->u.coreaudio.out));
	get_int("QEMU_COREAUDIO_BUFFER_COUNT",
	&dev->u.coreaudio.out->buffer_count,
	&dev->u.coreaudio.out->has_buffer_count);
	}

	/* dsound */
	static void handle_dsound(Audiodev *dev)
	{
	get_millis_to_usecs("QEMU_DSOUND_LATENCY_MILLIS",
	&dev->u.dsound.latency, &dev->u.dsound.has_latency);
	get_bytes_to_usecs("QEMU_DSOUND_BUFSIZE_OUT",
	&dev->u.dsound.out->buffer_length,
	&dev->u.dsound.out->has_buffer_length,
	dev->u.dsound.out);
	get_bytes_to_usecs("QEMU_DSOUND_BUFSIZE_IN",
	&dev->u.dsound.in->buffer_length,
	&dev->u.dsound.in->has_buffer_length,
	dev->u.dsound.in);
	}

	/* OSS */
	static void handle_oss_per_direction(
	AudiodevOssPerDirectionOptions opdo, const char try_poll_env,
	const char *dev_env)
	{
	get_bool(try_poll_env, &opdo->try_poll, &opdo->has_try_poll);
	get_str(dev_env, &opdo->dev, &opdo->has_dev);

	get_bytes_to_usecs("QEMU_OSS_FRAGSIZE",
	&opdo->buffer_length, &opdo->has_buffer_length,
	qapi_AudiodevOssPerDirectionOptions_base(opdo));
	get_int("QEMU_OSS_NFRAGS", &opdo->buffer_count,
	&opdo->has_buffer_count);
	}

	static void handle_oss(Audiodev *dev)
	{
	AudiodevOssOptions *oopt = &dev->u.oss;
	handle_oss_per_direction(oopt->in, "QEMU_AUDIO_ADC_TRY_POLL",
	"QEMU_OSS_ADC_DEV");
	handle_oss_per_direction(oopt->out, "QEMU_AUDIO_DAC_TRY_POLL",
	"QEMU_OSS_DAC_DEV");

	get_bool("QEMU_OSS_MMAP", &oopt->try_mmap, &oopt->has_try_mmap);
	get_bool("QEMU_OSS_EXCLUSIVE", &oopt->exclusive, &oopt->has_exclusive);
	get_int("QEMU_OSS_POLICY", &oopt->dsp_policy, &oopt->has_dsp_policy);
	}

	/* pulseaudio */
	static void handle_pa_per_direction(
	AudiodevPaPerDirectionOptions ppdo, const char env)
	{
	get_str(env, &ppdo->name, &ppdo->has_name);
	}

	static void handle_pa(Audiodev *dev)
	{
	handle_pa_per_direction(dev->u.pa.in, "QEMU_PA_SOURCE");
	handle_pa_per_direction(dev->u.pa.out, "QEMU_PA_SINK");

	get_samples_to_usecs(
	"QEMU_PA_SAMPLES", &dev->u.pa.in->buffer_length,
	&dev->u.pa.in->has_buffer_length,
	qapi_AudiodevPaPerDirectionOptions_base(dev->u.pa.in));
	get_samples_to_usecs(
	"QEMU_PA_SAMPLES", &dev->u.pa.out->buffer_length,
	&dev->u.pa.out->has_buffer_length,
	qapi_AudiodevPaPerDirectionOptions_base(dev->u.pa.out));

	get_str("QEMU_PA_SERVER", &dev->u.pa.server, &dev->u.pa.has_server);
	}

	/* SDL */
	static void handle_sdl(Audiodev *dev)
	{
	/* SDL is output only */
	get_samples_to_usecs("QEMU_SDL_SAMPLES", &dev->u.sdl.out->buffer_length,
	&dev->u.sdl.out->has_buffer_length,
	qapi_AudiodevSdlPerDirectionOptions_base(dev->u.sdl.out));
	}

	/* wav */
	static void handle_wav(Audiodev *dev)
	{
	get_int("QEMU_WAV_FREQUENCY",
	&dev->u.wav.out->frequency, &dev->u.wav.out->has_frequency);
	get_fmt("QEMU_WAV_FORMAT", &dev->u.wav.out->format,
	&dev->u.wav.out->has_format);
	get_int("QEMU_WAV_DAC_FIXED_CHANNELS",
	&dev->u.wav.out->channels, &dev->u.wav.out->has_channels);
	get_str("QEMU_WAV_PATH", &dev->u.wav.path, &dev->u.wav.has_path);
	}

	/* general */
	static void handle_per_direction(
	AudiodevPerDirectionOptions pdo, const char prefix)
	{
	char buf[64];
	size_t len = strlen(prefix);

	memcpy(buf, prefix, len);
	strcpy(buf + len, "FIXED_SETTINGS");
	get_bool(buf, &pdo->fixed_settings, &pdo->has_fixed_settings);

	strcpy(buf + len, "FIXED_FREQ");
	get_int(buf, &pdo->frequency, &pdo->has_frequency);

	strcpy(buf + len, "FIXED_FMT");
	get_fmt(buf, &pdo->format, &pdo->has_format);

	strcpy(buf + len, "FIXED_CHANNELS");
	get_int(buf, &pdo->channels, &pdo->has_channels);

	strcpy(buf + len, "VOICES");
	get_int(buf, &pdo->voices, &pdo->has_voices);
	}

	static AudiodevListEntry legacy_opt(const char drvname)
	{
	AudiodevListEntry *e = g_malloc0(sizeof(AudiodevListEntry));
	e->dev = g_malloc0(sizeof(Audiodev));
	e->dev->id = g_strdup(drvname);
	e->dev->driver = qapi_enum_parse(
	&AudiodevDriver_lookup, drvname, -1, &error_abort);

	audio_create_pdos(e->dev);

	handle_per_direction(audio_get_pdo_in(e->dev), "QEMU_AUDIO_ADC_");
	handle_per_direction(audio_get_pdo_out(e->dev), "QEMU_AUDIO_DAC_");

	/* Original description: Timer period in HZ (0 - use lowest possible) */
	get_int("QEMU_AUDIO_TIMER_PERIOD",
	&e->dev->timer_period, &e->dev->has_timer_period);
	if (e->dev->has_timer_period && e->dev->timer_period) {
	e->dev->timer_period = NANOSECONDS_PER_SECOND / 1000 /
	e->dev->timer_period;
	}

	switch (e->dev->driver) {
	case AUDIODEV_DRIVER_ALSA:
	handle_alsa(e->dev);
	break;

	case AUDIODEV_DRIVER_COREAUDIO:
	handle_coreaudio(e->dev);
	break;

	case AUDIODEV_DRIVER_DSOUND:
	handle_dsound(e->dev);
	break;

	case AUDIODEV_DRIVER_OSS:
	handle_oss(e->dev);
	break;

	case AUDIODEV_DRIVER_PA:
	handle_pa(e->dev);
	break;

	case AUDIODEV_DRIVER_SDL:
	handle_sdl(e->dev);
	break;

	case AUDIODEV_DRIVER_WAV:
	handle_wav(e->dev);
	break;

	default:
	break;
	}

	return e;
	}

	AudiodevListHead audio_handle_legacy_opts(void)
	{
	const char *drvname = getenv("QEMU_AUDIO_DRV");
	AudiodevListHead head = QSIMPLEQ_HEAD_INITIALIZER(head);

	if (drvname) {
	AudiodevListEntry *e;
	audio_driver *driver = audio_driver_lookup(drvname);
	if (!driver) {
	dolog("Unknown audio driver `%s'\n", drvname);
	exit(1);
	}
	e = legacy_opt(drvname);
	QSIMPLEQ_INSERT_TAIL(&head, e, next);
	} else {
	for (int i = 0; audio_prio_list[i]; i++) {
	audio_driver *driver = audio_driver_lookup(audio_prio_list[i]);
	if (driver && driver->can_be_default) {
	AudiodevListEntry *e = legacy_opt(driver->name);
	QSIMPLEQ_INSERT_TAIL(&head, e, next);
	}
	}
	if (QSIMPLEQ_EMPTY(&head)) {
	dolog("Internal error: no default audio driver available\n");
	exit(1);
	}
	}

	return head;
	}

	/* visitor to print -audiodev option */
	typedef struct {
	Visitor visitor;

	bool comma;
	GList *path;
	} LegacyPrintVisitor;

	static bool lv_start_struct(Visitor v, const char name, void **obj,
	size_t size, Error **errp)
	{
	LegacyPrintVisitor lv = (LegacyPrintVisitor ) v;
	lv->path = g_list_append(lv->path, g_strdup(name));
	return true;
	}

	static void lv_end_struct(Visitor v, void *obj)
	{
	LegacyPrintVisitor lv = (LegacyPrintVisitor ) v;
	lv->path = g_list_delete_link(lv->path, g_list_last(lv->path));
	}

	static void lv_print_key(Visitor v, const char name)
	{
	GList *e;
	LegacyPrintVisitor lv = (LegacyPrintVisitor ) v;
	if (lv->comma) {
	putchar(',');
	} else {
	lv->comma = true;
	}

	for (e = lv->path; e; e = e->next) {
	if (e->data) {
	printf("%s.", (const char *) e->data);
	}
	}

	printf("%s=", name);
	}

	static bool lv_type_int64(Visitor v, const char name, int64_t *obj,
	Error **errp)
	{
	lv_print_key(v, name);
	printf("%" PRIi64, *obj);
	return true;
	}

	static bool lv_type_uint64(Visitor v, const char name, uint64_t *obj,
	Error **errp)
	{
	lv_print_key(v, name);
	printf("%" PRIu64, *obj);
	return true;
	}

	static bool lv_type_bool(Visitor v, const char name, bool obj, Error *errp)
	{
	lv_print_key(v, name);
	printf("%s", *obj ? "on" : "off");
	return true;
	}

	static bool lv_type_str(Visitor v, const char name, char obj, Error errp)
	{
	const char str = obj;
	lv_print_key(v, name);

	while (*str) {
	if (*str == ',') {
	putchar(',');
	}
	putchar(*str++);
	}
	return true;
	}

	static void lv_complete(Visitor v, void opaque)
	{
	LegacyPrintVisitor lv = (LegacyPrintVisitor ) v;
	assert(lv->path == NULL);
	}

	static void lv_free(Visitor *v)
	{
	LegacyPrintVisitor lv = (LegacyPrintVisitor ) v;

	g_list_free_full(lv->path, g_free);
	g_free(lv);
	}

	static Visitor *legacy_visitor_new(void)
	{
	LegacyPrintVisitor *lv = g_malloc0(sizeof(LegacyPrintVisitor));

	lv->visitor.start_struct = lv_start_struct;
	lv->visitor.end_struct = lv_end_struct;
	/* lists not supported */
	lv->visitor.type_int64 = lv_type_int64;
	lv->visitor.type_uint64 = lv_type_uint64;
	lv->visitor.type_bool = lv_type_bool;
	lv->visitor.type_str = lv_type_str;

	lv->visitor.type = VISITOR_OUTPUT;
	lv->visitor.complete = lv_complete;
	lv->visitor.free = lv_free;

	return &lv->visitor;
	}

	void audio_legacy_help(void)
	{
	AudiodevListHead head;
	AudiodevListEntry *e;

	printf("Environment variable based configuration deprecated.\n");
	printf("Please use the new -audiodev option.\n");

	head = audio_handle_legacy_opts();
	printf("\nEquivalent -audiodev to your current environment variables:\n");
	if (!getenv("QEMU_AUDIO_DRV")) {
	printf("(Since you didn't specify QEMU_AUDIO_DRV, I'll list all "
	"possibilities)\n");
	}

	QSIMPLEQ_FOREACH(e, &head, next) {
	Visitor *v;
	Audiodev *dev = e->dev;
	printf("-audiodev ");

	v = legacy_visitor_new();
	visit_type_Audiodev(v, NULL, &dev, &error_abort);
	visit_free(v);

	printf("\n");
	}
	audio_free_audiodev_list(&head);
	}