[alsa-devel] [PATCH v5 06/10] ALSA: core: pass audio tstamp config from userspace

[Pierre-Louis Bossart]

Let userspace select audio timestamp config when the
STATUS_EXT ioctl is used, ignore and zero all
other fields
No change for the existing STATUS ioctl, parameters
are treated as read-only.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
---
 sound/core/pcm_native.c | 25 +++++++++++++++++++++----
 1 file changed, 21 insertions(+), 4 deletions(-)

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index d50f3e6..40d2943 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -753,12 +753,27 @@ int snd_pcm_status(struct snd_pcm_substream *substream,
 }
 
 static int snd_pcm_status_user(struct snd_pcm_substream *substream,
-			       struct snd_pcm_status __user * _status)
+			       struct snd_pcm_status __user * _status,
+			       bool ext)
 {
 	struct snd_pcm_status status;
 	int res;
-	
-	memset(&status, 0, sizeof(status));
+	u32  audio_tstamp_data;
+	u32  __user *_audio_tstamp_data;
+
+	if (ext == false) {
+		memset(&status, 0, sizeof(status));
+	} else {
+		/*
+		 * parameters are read/write, get audio_tstamp_data from user,
+		 * ignore rest of status structure
+		 */
+		_audio_tstamp_data = (u32 __user *)(&_status->audio_tstamp_data);
+		if (get_user(audio_tstamp_data, _audio_tstamp_data))
+			return -EFAULT;
+		memset(&status, 0, sizeof(status));
+		status.audio_tstamp_data = audio_tstamp_data;
+	}
 	res = snd_pcm_status(substream, &status);
 	if (res < 0)
 		return res;
@@ -2723,7 +2738,9 @@ static int snd_pcm_common_ioctl1(struct file *file,
 	case SNDRV_PCM_IOCTL_SW_PARAMS:
 		return snd_pcm_sw_params_user(substream, arg);
 	case SNDRV_PCM_IOCTL_STATUS:
-		return snd_pcm_status_user(substream, arg);
+		return snd_pcm_status_user(substream, arg, false);
+	case SNDRV_PCM_IOCTL_STATUS_EXT:
+		return snd_pcm_status_user(substream, arg, true);
 	case SNDRV_PCM_IOCTL_CHANNEL_INFO:
 		return snd_pcm_channel_info_user(substream, arg);
 	case SNDRV_PCM_IOCTL_PREPARE:
-- 
1.9.1