Add protocl version check

- Added protocl version check.  The caller of snd_pcm_{io|ext}plug_create()
  must fill version field with SND_PCM_{IO|EXT}PLUG_VERSION beforehand.

- Added poll_descriptors and poll_descriptors_count callbacks for ioplug.

include/pcm_extplug.h

@@ -32,8 +32,23 @@ enum {
 typedef struct snd_pcm_extplug snd_pcm_extplug_t;
 typedef struct snd_pcm_extplug_callback snd_pcm_extplug_callback_t;
 
+/**
+ * Protocol version
+ */
+#define SND_PCM_EXTPLUG_VERSION_MAJOR	1
+#define SND_PCM_EXTPLUG_VERSION_MINOR	0
+#define SND_PCM_EXTPLUG_VERSION_TINY	0
+#define SND_PCM_EXTPLUG_VERSION		((SND_PCM_EXTPLUG_VERSION_MAJOR<<16) |\
+					 (SND_PCM_EXTPLUG_VERSION_MINOR<<8) |\
+					 (SND_PCM_EXTPLUG_VERSION_TINY))
+
 /** handle of extplug */
 struct snd_pcm_extplug {
+	/**
+	 * protocol version; SND_PCM_EXTPLUG_VERSION must be filled here
+	 * before calling #snd_pcm_extplug_create()
+	 */
+	unsigned int version;
 	/**
 	 * name of this plugin; must be filled before calling #snd_pcm_extplug_create()
 	 */

include/pcm_ioplug.h

@@ -42,8 +42,23 @@ typedef struct snd_pcm_ioplug_callback snd_pcm_ioplug_callback_t;
  */
 #define SND_PCM_IOPLUG_FLAG_LISTED	(1<<0)		/* list up this PCM */
 
+/**
+ * Protocol version
+ */
+#define SND_PCM_IOPLUG_VERSION_MAJOR	1
+#define SND_PCM_IOPLUG_VERSION_MINOR	0
+#define SND_PCM_IOPLUG_VERSION_TINY	0
+#define SND_PCM_IOPLUG_VERSION		((SND_PCM_IOPLUG_VERSION_MAJOR<<16) |\
+					 (SND_PCM_IOPLUG_VERSION_MINOR<<8) |\
+					 (SND_PCM_IOPLUG_VERSION_TINY))
+
 /** handle of ioplug */
 struct snd_pcm_ioplug {
+	/**
+	 * protocol version; SND_PCM_IOPLUG_VERSION must be filled here
+	 * before calling #snd_pcm_ioplug_create()
+	 */
+	unsigned int version;
 	/**
 	 * name of this plugin; must be filled before calling #snd_pcm_ioplug_create()
 	 */
@@ -132,6 +147,14 @@ struct snd_pcm_ioplug_callback {
 	 * resume; optional
 	 */
 	int (*resume)(snd_pcm_ioplug_t *io);
+	/**
+	 * poll descriptors count; optional
+	 */
+	int (*poll_descriptors_count)(snd_pcm_ioplug_t *io);
+	/**
+	 * poll descriptors; optional
+	 */
+	int (*poll_descriptors)(snd_pcm_ioplug_t *io, struct pollfd *pfd, unsigned int space);
 	/**
 	 * mangle poll events; optional
 	 */

src/pcm/pcm_extplug.c

@@ -423,6 +423,8 @@ static snd_pcm_ops_t snd_pcm_extplug_ops = {
 	.dump = snd_pcm_extplug_dump,
 	.nonblock = snd_pcm_generic_nonblock,
 	.async = snd_pcm_generic_async,
+	.poll_descriptors_count = snd_pcm_generic_poll_descriptors_count,
+	.poll_descriptors = snd_pcm_generic_poll_descriptors,
 	.poll_revents = snd_pcm_generic_poll_revents,
 	.mmap = snd_pcm_generic_mmap,
 	.munmap = snd_pcm_generic_munmap,
@@ -478,6 +480,11 @@ int snd_pcm_extplug_create(snd_pcm_extplug_t *extplug, const char *name,
 	assert(extplug->callback->transfer);
 	assert(slave_conf);
 
+	if (extplug->version != SND_PCM_EXTPLUG_VERSION) {
+		SNDERR("extplug: Plugin version mismatch\n");
+		return -ENXIO;
+	}
+
 	err = snd_pcm_slave_conf(root, slave_conf, &sconf, 0);
 	if (err < 0)
 		return err;

src/pcm/pcm_ioplug.c

@@ -238,7 +238,7 @@ static int snd_pcm_ioplug_hw_refine(snd_pcm_t *pcm, snd_pcm_hw_params_t *params)
 	int change = 0, change1, change2, err;
 	ioplug_priv_t *io = pcm->private_data;
 	struct snd_ext_parm *p;
-	int i;
+	unsigned int i;
 
 	/* access, format */
 	for (i = SND_PCM_IOPLUG_HW_ACCESS; i <= SND_PCM_IOPLUG_HW_FORMAT; i++) {
@@ -616,6 +616,33 @@ static int snd_pcm_ioplug_nonblock(snd_pcm_t *pcm, int nonblock)
 	return 0;
 }
 
+static int snd_pcm_ioplug_poll_descriptors_count(snd_pcm_t *pcm)
+{
+	ioplug_priv_t *io = pcm->private_data;
+
+	if (io->data->callback->poll_descriptors_count)
+		return io->data->callback->poll_descriptors_count(io->data);
+	else
+		return 1;
+}
+
+static int snd_pcm_ioplug_poll_descriptors(snd_pcm_t *pcm, struct pollfd *pfds, unsigned int space)
+{
+	ioplug_priv_t *io = pcm->private_data;
+
+	if (io->data->callback->poll_descriptors)
+		return io->data->callback->poll_descriptors(io->data, pfds, space);
+	if (pcm->poll_fd < 0)
+		return -EIO;
+	if (space >= 1 && pfds) {
+		pfds->fd = pcm->poll_fd;
+		pfds->events = pcm->poll_events | POLLERR | POLLNVAL;
+	} else {
+		return 0;
+	}
+	return 1;
+}
+
 static int snd_pcm_ioplug_poll_revents(snd_pcm_t *pcm, struct pollfd *pfds, unsigned int nfds, unsigned short *revents)
 {
 	ioplug_priv_t *io = pcm->private_data;
@@ -685,6 +712,8 @@ static snd_pcm_ops_t snd_pcm_ioplug_ops = {
 	.close = snd_pcm_ioplug_close,
 	.nonblock = snd_pcm_ioplug_nonblock,
 	.async = snd_pcm_ioplug_async,
+	.poll_descriptors_count = snd_pcm_ioplug_poll_descriptors_count,
+	.poll_descriptors = snd_pcm_ioplug_poll_descriptors,
 	.poll_revents = snd_pcm_ioplug_poll_revents,
 	.info = snd_pcm_ioplug_info,
 	.hw_refine = snd_pcm_ioplug_hw_refine,
@@ -764,6 +793,11 @@ int snd_pcm_ioplug_create(snd_pcm_ioplug_t *ioplug, const char *name,
 	       ioplug->callback->stop &&
 	       ioplug->callback->pointer);
 
+	if (ioplug->version != SND_PCM_IOPLUG_VERSION) {
+		SNDERR("ioplug: Plugin version mismatch\n");
+		return -ENXIO;
+	}
+
 	io = calloc(1, sizeof(*io));
 	if (! io)
 		return -ENOMEM;