[vlc-devel] [PATCH] aout: add device cycling helper

[Victorien Le Couviour--Tuffet]

---
 include/vlc_aout.h        |   1 +
 src/audio_output/output.c | 101 +++++++++++++++++++++++++++++++-------
 src/libvlccore.sym        |   1 +
 3 files changed, 84 insertions(+), 19 deletions(-)

diff --git a/include/vlc_aout.h b/include/vlc_aout.h
index aa49884001..ef78127c13 100644
--- a/include/vlc_aout.h
+++ b/include/vlc_aout.h
@@ -373,6 +373,7 @@ VLC_API int aout_MuteGet (audio_output_t *);
 VLC_API int aout_MuteSet (audio_output_t *, bool);
 VLC_API char *aout_DeviceGet (audio_output_t *);
 VLC_API int aout_DeviceSet (audio_output_t *, const char *);
+VLC_API int aout_DeviceNext (audio_output_t *, char **);
 VLC_API int aout_DevicesList (audio_output_t *, char ***, char ***);
 
 /**
diff --git a/src/audio_output/output.c b/src/audio_output/output.c
index 019797c5ef..fa07569925 100644
--- a/src/audio_output/output.c
+++ b/src/audio_output/output.c
@@ -686,6 +686,14 @@ char *aout_DeviceGet (audio_output_t *aout)
     return var_GetNonEmptyString (aout, "device");
 }
 
+static int aout_DeviceSetLocked(audio_output_t *aout, char const *id)
+{
+    aout_owner_t *owner = aout_owner(aout);
+    vlc_mutex_assert(&owner->lock);
+    vlc_mutex_assert(&owner->dev.lock);
+    return aout->device_select(aout, id) ? -1 : 0;
+}
+
 /**
  * Selects an audio output device.
  * \param id device ID to select, or NULL for the default device
@@ -693,32 +701,23 @@ char *aout_DeviceGet (audio_output_t *aout)
  */
 int aout_DeviceSet (audio_output_t *aout, const char *id)
 {
-    int ret;
-
     aout_OutputLock(aout);
-    ret = aout->device_select(aout, id);
+    vlc_mutex_t *lock = &aout_owner(aout)->dev.lock;
+    vlc_mutex_lock(lock);
+    int ret = aout_DeviceSetLocked(aout, id);
+    vlc_mutex_unlock(lock);
     aout_OutputUnlock(aout);
-    return ret ? -1 : 0;
+    return ret;
 }
 
-/**
- * Enumerates possible audio output devices.
- *
- * The function will heap-allocate two tables of heap-allocated strings;
- * the caller is responsible for freeing all strings and both tables.
- *
- * \param ids pointer to a table of device identifiers [OUT]
- * \param names pointer to a table of device human-readable descriptions [OUT]
- * \return the number of devices, or negative on error.
- * \note In case of error, *ids and *names are undefined.
- */
-int aout_DevicesList (audio_output_t *aout, char ***ids, char ***names)
+static int aout_DevicesListLocked(audio_output_t *aout,
+                                  char ***ids, char ***names)
 {
     aout_owner_t *owner = aout_owner (aout);
+    vlc_mutex_assert(&owner->dev.lock);
     char **tabid, **tabname;
     unsigned i = 0;
 
-    vlc_mutex_lock (&owner->dev.lock);
     tabid = vlc_alloc (owner->dev.count, sizeof (*tabid));
     tabname = vlc_alloc (owner->dev.count, sizeof (*tabname));
 
@@ -743,12 +742,10 @@ int aout_DevicesList (audio_output_t *aout, char ***ids, char ***names)
 
         i++;
     }
-    vlc_mutex_unlock (&owner->dev.lock);
 
     return i;
 
 error:
-    vlc_mutex_unlock(&owner->dev.lock);
     while (i > 0)
     {
         i--;
@@ -760,6 +757,72 @@ error:
     return -1;
 }
 
+/**
+ * Enumerates possible audio output devices.
+ *
+ * The function will heap-allocate two tables of heap-allocated strings;
+ * the caller is responsible for freeing all strings and both tables.
+ *
+ * \param ids pointer to a table of device identifiers [OUT]
+ * \param names pointer to a table of device human-readable descriptions [OUT]
+ * \return the number of devices, or negative on error.
+ * \note In case of error, *ids and *names are undefined.
+ */
+int aout_DevicesList (audio_output_t *aout, char ***ids, char ***names)
+{
+    vlc_mutex_t *lock = &aout_owner(aout)->dev.lock;
+    vlc_mutex_lock(lock);
+    int ret = aout_DevicesListLocked(aout, ids, names);
+    vlc_mutex_unlock(lock);
+    return ret;
+}
+
+/**
+ * Cycle through audio output devices.
+ * \param p_name pointer to the selected device human-readable description [OUT]
+ * \return zero on success, non-zero on error.
+ */
+int aout_DeviceNext (audio_output_t *aout, char **p_name)
+{
+    int ret = -1;
+    aout_OutputLock(aout);
+    vlc_mutex_t *lock = &aout_owner(aout)->dev.lock;
+    vlc_mutex_lock(lock);
+
+    char **ids, **names;
+    int n = aout_DevicesListLocked(aout, &ids, &names);
+    if (n == -1)
+        goto end;
+    char *device = aout_DeviceGet(aout);
+    if (!device)
+        goto no_dev;
+
+    int index;
+    for (index = 0; index < n; ++index)
+        if (!strcmp(ids[index], device))
+        {
+            index = (index + 1) % n;
+            break;
+        }
+    ret = aout_DeviceSetLocked(aout, ids[index]);
+    if (p_name != NULL)
+        *p_name = strdup(names[index]);
+
+    free(device);
+no_dev:
+    for (int i = 0; i < n; ++i)
+    {
+        free(ids[i]);
+        free(names[i]);
+    }
+    free(ids);
+    free(names);
+end:
+    vlc_mutex_unlock(lock);
+    aout_OutputUnlock(aout);
+    return ret;
+}
+
 static void aout_ChangeViewpoint(audio_output_t *aout,
                                  const vlc_viewpoint_t *p_viewpoint)
 {
diff --git a/src/libvlccore.sym b/src/libvlccore.sym
index d4db4ccc51..41af4b48db 100644
--- a/src/libvlccore.sym
+++ b/src/libvlccore.sym
@@ -20,6 +20,7 @@ aout_MuteSet
 aout_MuteGet
 aout_DeviceGet
 aout_DeviceSet
+aout_DeviceNext
 aout_DevicesList
 aout_FiltersNew
 aout_FiltersChangeViewpoint
-- 
2.19.1