[alsa-devel] [PATCH 2/3] Add snd_{ctl|pcm}_open_fallback() functions

[Takashi Iwai]

This patch adds new API functions, snd_ctl_open_fallback() and
snd_pcm_open_fallback().  These are just like snd_*_open_lconf() but
used to open a fallback PCM/control.  The difference is that it replaces
the name string with the given original name, so that hctl and other
upper-layers will recognize it as an alias.

Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 include/control.h     |    1 +
 include/pcm.h         |    3 +++
 src/control/control.c |   22 ++++++++++++++++++++++
 src/pcm/pcm.c         |   24 ++++++++++++++++++++++++
 4 files changed, 50 insertions(+), 0 deletions(-)

diff --git a/include/control.h b/include/control.h
index e8f38bb..f265e34 100644
--- a/include/control.h
+++ b/include/control.h
@@ -224,6 +224,7 @@ char *snd_device_name_get_hint(const void *hint, const char *id);
 
 int snd_ctl_open(snd_ctl_t **ctl, const char *name, int mode);
 int snd_ctl_open_lconf(snd_ctl_t **ctl, const char *name, int mode, snd_config_t *lconf);
+int snd_ctl_open_fallback(snd_ctl_t **ctl, snd_config_t *root, const char *name, const char *orig_name, int mode);
 int snd_ctl_close(snd_ctl_t *ctl);
 int snd_ctl_nonblock(snd_ctl_t *ctl, int nonblock);
 int snd_async_add_ctl_handler(snd_async_handler_t **handler, snd_ctl_t *ctl, 
diff --git a/include/pcm.h b/include/pcm.h
index 7243ffb..be355a9 100644
--- a/include/pcm.h
+++ b/include/pcm.h
@@ -410,6 +410,9 @@ int snd_pcm_open(snd_pcm_t **pcm, const char *name,
 int snd_pcm_open_lconf(snd_pcm_t **pcm, const char *name, 
 		       snd_pcm_stream_t stream, int mode,
 		       snd_config_t *lconf);
+int snd_pcm_open_fallback(snd_pcm_t **pcm, snd_config_t *root,
+			  const char *name, const char *orig_name,
+			  snd_pcm_stream_t stream, int mode);
 
 int snd_pcm_close(snd_pcm_t *pcm);
 const char *snd_pcm_name(snd_pcm_t *pcm);
diff --git a/src/control/control.c b/src/control/control.c
index 19e9389..cd17c6f 100644
--- a/src/control/control.c
+++ b/src/control/control.c
@@ -919,6 +919,28 @@ int snd_ctl_open_lconf(snd_ctl_t **ctlp, const char *name,
 	return snd_ctl_open_noupdate(ctlp, lconf, name, mode);
 }
 
+/**
+ * \brief Opens a fallback CTL
+ * \param ctlp Returned CTL handle
+ * \param root Configuration root
+ * \param name ASCII identifier of the CTL handle used as fallback
+ * \param orig_name The original ASCII name
+ * \param mode Open mode (see #SND_CTL_NONBLOCK, #SND_CTL_ASYNC)
+ * \return 0 on success otherwise a negative error code
+ */
+int snd_ctl_open_fallback(snd_ctl_t **ctlp, snd_config_t *root,
+			  const char *name, const char *orig_name, int mode)
+{
+	int err;
+	assert(ctlp && name && root);
+	err = snd_ctl_open_noupdate(ctlp, root, name, mode);
+	if (err >= 0) {
+		free((*ctlp)->name);
+		(*ctlp)->name = orig_name ? strdup(orig_name) : NULL;
+	}
+	return err;
+}
+
 #ifndef DOC_HIDDEN
 #define TYPE(v) [SND_CTL_ELEM_TYPE_##v] = #v
 #define IFACE(v) [SND_CTL_ELEM_IFACE_##v] = #v
diff --git a/src/pcm/pcm.c b/src/pcm/pcm.c
index 02dea0d..12f8cd0 100644
--- a/src/pcm/pcm.c
+++ b/src/pcm/pcm.c
@@ -2259,6 +2259,30 @@ int snd_pcm_open_lconf(snd_pcm_t **pcmp, const char *name,
 	return snd_pcm_open_noupdate(pcmp, lconf, name, stream, mode, 0);
 }
 
+/**
+ * \brief Opens a fallback PCM
+ * \param pcmp Returned PCM handle
+ * \param root Configuration root
+ * \param name ASCII identifier of the PCM handle
+ * \param orig_name The original ASCII name
+ * \param stream Wanted stream
+ * \param mode Open mode (see #SND_PCM_NONBLOCK, #SND_PCM_ASYNC)
+ * \return 0 on success otherwise a negative error code
+ */
+int snd_pcm_open_fallback(snd_pcm_t **pcmp, snd_config_t *root,
+			  const char *name, const char *orig_name,
+			  snd_pcm_stream_t stream, int mode)
+{
+	int err;
+	assert(pcmp && name && root);
+	err = snd_pcm_open_noupdate(pcmp, root, name, stream, mode, 0);
+	if (err >= 0) {
+		free((*pcmp)->name);
+		(*pcmp)->name = orig_name ? strdup(orig_name) : NULL;
+	}
+	return err;
+}
+
 #ifndef DOC_HIDDEN
 int snd_pcm_new(snd_pcm_t **pcmp, snd_pcm_type_t type, const char *name,
 		snd_pcm_stream_t stream, int mode)
-- 
1.7.6