Re: [PATCH] audio/dsound: fix invalid parameters error

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 1/17/20 7:26 PM, KJ Liew wrote:
> QEMU Windows has broken dsound backend since the rewrite of audio API in
> version 4.2.0. Both playback and capture buffers failed to lock with
> invalid parameters error.

Fixes: 7fa9754ac88 (dsoundaudio: port to the new audio backend api)

Cc'ing Zoltán who wrote 7fa9754ac88, and Gerd (the maintainer of this file):

   $ ./scripts/get_maintainer.pl -f audio/dsoundaudio.c
   Gerd Hoffmann <kraxel@redhat.com> (maintainer:Audio)

> --- ../orig/qemu-4.2.0/audio/dsoundaudio.c	2019-12-12 10:20:47.000000000 -0800
> +++ ../qemu-4.2.0/audio/dsoundaudio.c	2020-01-17 08:05:46.783966900 -0800
> @@ -53,6 +53,7 @@
>   typedef struct {
>       HWVoiceOut hw;
>       LPDIRECTSOUNDBUFFER dsound_buffer;
> +    void *last_buf;
>       dsound *s;
>   } DSoundVoiceOut;
>   
> @@ -414,10 +415,10 @@
>       DSoundVoiceOut *ds = (DSoundVoiceOut *) hw;
>       LPDIRECTSOUNDBUFFER dsb = ds->dsound_buffer;
>       HRESULT hr;
> -    DWORD ppos, act_size;
> +    DWORD ppos, act_size, last_size;
>       size_t req_size;
>       int err;
> -    void *ret;
> +    void *ret, *last_ret;
>   
>       hr = IDirectSoundBuffer_GetCurrentPosition(dsb, &ppos, NULL);
>       if (FAILED(hr)) {
> @@ -426,17 +427,24 @@
>           return NULL;
>       }
>   
> +    if (ppos == hw->pos_emul) {
> +        *size = 0;
> +        return ds->last_buf;
> +    }
> +
>       req_size = audio_ring_dist(ppos, hw->pos_emul, hw->size_emul);
>       req_size = MIN(req_size, hw->size_emul - hw->pos_emul);
>   
> -    err = dsound_lock_out(dsb, &hw->info, hw->pos_emul, req_size, &ret, NULL,
> -                          &act_size, NULL, false, ds->s);
> +    err = dsound_lock_out(dsb, &hw->info, hw->pos_emul, req_size, &ret, &last_ret,
> +                          &act_size, &last_size, false, ds->s);
>       if (err) {
>           dolog("Failed to lock buffer\n");
>           *size = 0;
>           return NULL;
>       }
>   
> +    ds->last_buf = g_realloc(ds->last_buf, act_size);
> +    memcpy(ds->last_buf, ret, act_size);
>       *size = act_size;
>       return ret;
>   }
> @@ -445,6 +453,8 @@
>   {
>       DSoundVoiceOut *ds = (DSoundVoiceOut *) hw;
>       LPDIRECTSOUNDBUFFER dsb = ds->dsound_buffer;
> +    if (len == 0)
> +        return 0;
>       int err = dsound_unlock_out(dsb, buf, NULL, len, 0);
>   
>       if (err) {
> @@ -508,10 +518,10 @@
>       DSoundVoiceIn *ds = (DSoundVoiceIn *) hw;
>       LPDIRECTSOUNDCAPTUREBUFFER dscb = ds->dsound_capture_buffer;
>       HRESULT hr;
> -    DWORD cpos, act_size;
> +    DWORD cpos, act_size, last_size;
>       size_t req_size;
>       int err;
> -    void *ret;
> +    void *ret, *last_ret;
>   
>       hr = IDirectSoundCaptureBuffer_GetCurrentPosition(dscb, &cpos, NULL);
>       if (FAILED(hr)) {
> @@ -520,11 +530,16 @@
>           return NULL;
>       }
>   
> +    if (cpos == hw->pos_emul) {
> +        *size = 0;
> +        return NULL;
> +    }
> +
>       req_size = audio_ring_dist(cpos, hw->pos_emul, hw->size_emul);
>       req_size = MIN(req_size, hw->size_emul - hw->pos_emul);
>   
> -    err = dsound_lock_in(dscb, &hw->info, hw->pos_emul, req_size, &ret, NULL,
> -                         &act_size, NULL, false, ds->s);
> +    err = dsound_lock_in(dscb, &hw->info, hw->pos_emul, req_size, &ret, &last_ret,
> +                         &act_size, &last_size, false, ds->s);
>       if (err) {
>           dolog("Failed to lock buffer\n");
>           *size = 0;
>