input item: add a locked version of GetMeta()

Expose a function which does not lock internally so that we can retrieve
several meta values in a row without locking/unlocking.

Signed-off-by: Thomas Guillem <thomas@gllm.fr>

include/vlc_input_item.h

@@ -271,6 +271,7 @@ VLC_API bool input_item_HasErrorWhenReading( input_item_t * );
 VLC_API void input_item_SetMeta( input_item_t *, vlc_meta_type_t meta_type, const char *psz_val );
 VLC_API bool input_item_MetaMatch( input_item_t *p_i, vlc_meta_type_t meta_type, const char *psz );
 VLC_API char * input_item_GetMeta( input_item_t *p_i, vlc_meta_type_t meta_type ) VLC_USED;
+VLC_API const char *input_item_GetMetaLocked(input_item_t *, vlc_meta_type_t meta_type);
 VLC_API char * input_item_GetName( input_item_t * p_i ) VLC_USED;
 VLC_API char * input_item_GetTitleFbName( input_item_t * p_i ) VLC_USED;
 VLC_API char * input_item_GetURI( input_item_t * p_i ) VLC_USED;

src/input/item.c

@@ -251,20 +251,22 @@ bool input_item_MetaMatch( input_item_t *p_i,
     return b_ret;
 }
 
-char *input_item_GetMeta( input_item_t *p_i, vlc_meta_type_t meta_type )
+const char *input_item_GetMetaLocked(input_item_t *item,
+                                     vlc_meta_type_t meta_type)
 {
-    vlc_mutex_lock( &p_i->lock );
+    vlc_mutex_assert(&item->lock);
 
-    if( !p_i->p_meta )
-    {
-        vlc_mutex_unlock( &p_i->lock );
+    if (!item->p_meta)
         return NULL;
-    }
 
-    char *psz = NULL;
-    if( vlc_meta_Get( p_i->p_meta, meta_type ) )
-        psz = strdup( vlc_meta_Get( p_i->p_meta, meta_type ) );
+    return vlc_meta_Get(item->p_meta, meta_type);
+}
 
+char *input_item_GetMeta( input_item_t *p_i, vlc_meta_type_t meta_type )
+{
+    vlc_mutex_lock( &p_i->lock );
+    const char *value = input_item_GetMetaLocked( p_i, meta_type );
+    char *psz = value ? strdup( value ) : NULL;
     vlc_mutex_unlock( &p_i->lock );
     return psz;
 }

src/libvlccore.sym

@@ -173,6 +173,7 @@ input_item_DelInfo
 input_item_GetDuration
 input_item_GetInfo
 input_item_GetMeta
+input_item_GetMetaLocked
 input_item_GetName
 input_item_GetNowPlayingFb
 input_item_GetTitleFbName