Patch by Jilles Tjoelker. Fixes crash in playlist due to negative index in...

Patch by Jilles Tjoelker. Fixes crash in playlist due to negative index in playlist item array. Added boundary check to solve this.

src/playlist/control.c

@@ -386,12 +386,14 @@ playlist_item_t * playlist_NextItem( playlist_t *p_playlist )
         else
             p_playlist->i_current_index = -1;
 
-        if( p_playlist->current.i_size && i_skip > 0 )
+        if( p_playlist->current.i_size && (i_skip > 0) )
         {
+            if( p_playlist->i_current_index < -1 )
+                p_playlist->i_current_index = -1;
             for( i = i_skip; i > 0 ; i-- )
             {
                 p_playlist->i_current_index++;
-                if( p_playlist->i_current_index == p_playlist->current.i_size )
+                if( p_playlist->i_current_index >= p_playlist->current.i_size )
                 {
                     PL_DEBUG( "looping - restarting at beginning of node" );
                     p_playlist->i_current_index = 0;
@@ -400,12 +402,12 @@ playlist_item_t * playlist_NextItem( playlist_t *p_playlist )
             p_new = ARRAY_VAL( p_playlist->current,
                                p_playlist->i_current_index );
         }
-        else if( p_playlist->current.i_size && i_skip < 0 )
+        else if( p_playlist->current.i_size && (i_skip < 0) )
         {
             for( i = i_skip; i < 0 ; i++ )
             {
                 p_playlist->i_current_index--;
-                if( p_playlist->i_current_index == -1 )
+                if( p_playlist->i_current_index <= -1 )
                 {
                     PL_DEBUG( "looping - restarting at end of node" );
                     p_playlist->i_current_index = p_playlist->current.i_size-1;