pcm: add SND_CTL_EINTR open mode

Add possibility to return -EINTR instead waiting for the event. The
applications may want to handle -EINTR condition themselves.

BugLink: https://github.com/alsa-project/alsa-lib/issues/228
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

include/control.h

@@ -356,6 +356,9 @@ typedef enum _snd_ctl_type {
 /** Read only (flag for open mode) \hideinitializer */
 #define SND_CTL_READONLY		0x0004
 
+/** Return EINTR instead blocking (flag for open mode) \hideinitializer */
+#define SND_CTL_EINTR			0x0080
+
 /** CTL handle */
 typedef struct _snd_ctl snd_ctl_t;
 

src/control/control.c

@@ -265,13 +265,14 @@ int snd_ctl_nonblock(snd_ctl_t *ctl, int nonblock)
 }
 
 #ifndef DOC_HIDDEN
-int snd_ctl_new(snd_ctl_t **ctlp, snd_ctl_type_t type, const char *name)
+int snd_ctl_new(snd_ctl_t **ctlp, snd_ctl_type_t type, const char *name, int mode)
 {
 	snd_ctl_t *ctl;
 	ctl = calloc(1, sizeof(*ctl));
 	if (!ctl)
 		return -ENOMEM;
 	ctl->type = type;
+	ctl->mode = mode;
 	if (name)
 		ctl->name = strdup(name);
 	INIT_LIST_HEAD(&ctl->async_handlers);

src/control/control_ext.c

@@ -716,7 +716,7 @@ int snd_ctl_ext_create(snd_ctl_ext_t *ext, const char *name, int mode)
 		return -ENXIO;
 	}
 
-	err = snd_ctl_new(&ctl, SND_CTL_TYPE_EXT, name);
+	err = snd_ctl_new(&ctl, SND_CTL_TYPE_EXT, name, mode);
 	if (err < 0)
 		return err;
 

src/control/control_hw.c

@@ -444,7 +444,7 @@ int snd_ctl_hw_open(snd_ctl_t **handle, const char *name, int card, int mode)
 	hw->fd = fd;
 	hw->protocol = ver;
 
-	err = snd_ctl_new(&ctl, SND_CTL_TYPE_HW, name);
+	err = snd_ctl_new(&ctl, SND_CTL_TYPE_HW, name, mode);
 	if (err < 0) {
 		close(fd);
 		free(hw);

src/control/control_local.h

@@ -62,6 +62,7 @@ struct _snd_ctl {
 	snd_ctl_type_t type;
 	const snd_ctl_ops_t *ops;
 	void *private_data;
+	int mode;
 	int nonblock;
 	int poll_fd;
 	struct list_head async_handlers;
@@ -93,7 +94,7 @@ struct _snd_hctl {
 /* make local functions really local */
 #define snd_ctl_new	snd1_ctl_new
 
-int snd_ctl_new(snd_ctl_t **ctlp, snd_ctl_type_t type, const char *name);
+int snd_ctl_new(snd_ctl_t **ctlp, snd_ctl_type_t type, const char *name, int mode);
 int _snd_ctl_poll_descriptor(snd_ctl_t *ctl);
 #define _snd_ctl_async_descriptor _snd_ctl_poll_descriptor
 int snd_ctl_hw_open(snd_ctl_t **handle, const char *name, int card, int mode);

src/control/control_remap.c

@@ -1148,7 +1148,7 @@ static int parse_map(snd_ctl_remap_t *priv, snd_config_t *conf)
  *          changed in future.
  */
 int snd_ctl_remap_open(snd_ctl_t **handlep, const char *name, snd_config_t *remap,
-		       snd_config_t *map, snd_ctl_t *child, int mode ATTRIBUTE_UNUSED)
+		       snd_config_t *map, snd_ctl_t *child, int mode)
 {
 	snd_ctl_remap_t *priv;
 	snd_ctl_t *ctl;
@@ -1195,7 +1195,7 @@ int snd_ctl_remap_open(snd_ctl_t **handlep, const char *name, snd_config_t *rema
 	priv->numid_remap_active = priv->map_items > 0;
 
 	priv->child = child;
-	err = snd_ctl_new(&ctl, SND_CTL_TYPE_REMAP, name);
+	err = snd_ctl_new(&ctl, SND_CTL_TYPE_REMAP, name, mode);
 	if (err < 0) {
 		result = err;
 		goto _err;

src/control/control_shm.c

@@ -502,7 +502,7 @@ int snd_ctl_shm_open(snd_ctl_t **handlep, const char *name, const char *sockname
 	shm->socket = sock;
 	shm->ctrl = ctrl;
 
-	err = snd_ctl_new(&ctl, SND_CTL_TYPE_SHM, name);
+	err = snd_ctl_new(&ctl, SND_CTL_TYPE_SHM, name, mode);
 	if (err < 0) {
 		result = err;
 		goto _err;

src/control/hcontrol.c

@@ -696,7 +696,7 @@ int snd_hctl_wait(snd_hctl_t *hctl, int timeout)
 		pollio = 0;
 		err_poll = poll(pfd, npfds, timeout);
 		if (err_poll < 0) {
-			if (errno == EINTR && !CTLINABORT(hctl->ctl))
+			if (errno == EINTR && !CTLINABORT(hctl->ctl) && !(hctl->ctl->mode & SND_CTL_EINTR))
 				continue;
 			return -errno;
 		}