V4L2: always call libv4l2 when available instead of pointers

libv4l2 directly wraps the system call if it does not know the file
descriptor. There is no need for VLC to reinvent the wheel.

modules/access/v4l2.c

@@ -581,47 +581,11 @@ struct demux_sys_t
     char *psz_set_ctrls;
 
 #ifdef HAVE_LIBV4L2
-    /* */
-    int (*pf_close)( int );
-    int (*pf_dup)( int );
-    int (*pf_ioctl)( int, unsigned long int, ... );
-    ssize_t (*pf_read)( int, void *, size_t );
-    void *(*pf_mmap)( void *, size_t, int, int, int, off_t );
-    int (*pf_munmap)( void *, size_t );
     bool b_libv4l2;
 #endif
 };
 
-#ifdef HAVE_LIBV4L2
-static void use_kernel_v4l2( demux_sys_t *p_sys )
-{
-    p_sys->pf_close = close;
-    p_sys->pf_dup = dup;
-    p_sys->pf_ioctl = ioctl;
-    p_sys->pf_read = read;
-    p_sys->pf_mmap = mmap;
-    p_sys->pf_munmap = munmap;
-    p_sys->b_libv4l2 = false;
-}
-
-static void use_libv4l2( demux_sys_t *p_sys )
-{
-    p_sys->pf_close = v4l2_close;
-    p_sys->pf_dup = v4l2_dup;
-    p_sys->pf_ioctl = v4l2_ioctl;
-    p_sys->pf_read = v4l2_read;
-    p_sys->pf_mmap = v4l2_mmap;
-    p_sys->pf_munmap = v4l2_munmap;
-    p_sys->b_libv4l2 = true;
-}
-
-#   define v4l2_close (p_sys->pf_close)
-#   define v4l2_dup (p_sys->pf_dup)
-#   define v4l2_ioctl (p_sys->pf_ioctl)
-#   define v4l2_read (p_sys->pf_read)
-#   define v4l2_mmap (p_sys->pf_mmap)
-#   define v4l2_munmap (p_sys->pf_munmap)
-#else
+#ifndef HAVE_LIBV4L2
 #   define v4l2_close close
 #   define v4l2_dup dup
 #   define v4l2_ioctl ioctl
@@ -680,13 +644,13 @@ static int DemuxOpen( vlc_object_t *p_this )
     if( !var_InheritBool( p_this, CFG_PREFIX "use-libv4l2" ) )
     {
         msg_Dbg( p_this, "Trying direct kernel v4l2" );
-        use_kernel_v4l2( p_sys );
+        p_sys->b_libv4l2 = false;
         if( FindMainDevice( p_this, p_sys, true ) == VLC_SUCCESS)
             return VLC_SUCCESS;
     }
 
     msg_Dbg( p_this, "Trying libv4l2 wrapper" );
-    use_libv4l2( p_sys );
+    p_sys->b_libv4l2 = true;
 #endif
     if( FindMainDevice( p_this, p_sys, true ) == VLC_SUCCESS)
         return VLC_SUCCESS;
@@ -1129,7 +1093,7 @@ static int AccessOpen( vlc_object_t * p_this )
     if( !var_InheritBool( p_this, CFG_PREFIX "use-libv4l2" ) )
     {
         msg_Dbg( p_this, "Trying direct kernel v4l2" );
-        use_kernel_v4l2( p_sys );
+        p_sys->b_libv4l2 = false;
         if( FindMainDevice( p_this, p_sys, false ) == VLC_SUCCESS)
         {
             if( p_sys->io == IO_METHOD_READ )
@@ -1145,7 +1109,7 @@ static int AccessOpen( vlc_object_t * p_this )
     }
 
     msg_Dbg( p_this, "Trying libv4l2 wrapper" );
-    use_libv4l2( p_sys );
+    p_sys->b_libv4l2 = true;
 #endif
     if( FindMainDevice( p_this, p_sys, false ) == VLC_SUCCESS )
     {