*: make internal pointer handling safer

src/util/frame/mod.rs

@@ -28,13 +28,33 @@ pub struct Packet {
 
 #[derive(PartialEq, Eq)]
 pub struct Frame {
-	pub ptr: *mut AVFrame,
+	ptr: *mut AVFrame,
+
+	_own: bool,
+}
+
+impl Frame {
+	pub unsafe fn wrap(ptr: *mut AVFrame) -> Self {
+		Frame { ptr: ptr, _own: false }
+	}
+
+	pub unsafe fn empty() -> Self {
+		Frame { ptr: av_frame_alloc(), _own: true }
+	}
+
+	pub unsafe fn as_ptr(&self) -> *const AVFrame {
+		self.ptr as *const _
+	}
+
+	pub unsafe fn as_mut_ptr(&mut self) -> *mut AVFrame {
+		self.ptr
+	}
 }
 
 impl Frame {
 	pub fn is_key(&self) -> bool {
 		unsafe {
-			(*self.ptr).key_frame == 1
+			(*self.as_ptr()).key_frame == 1
 		}
 	}
 
@@ -45,25 +65,25 @@ impl Frame {
 	pub fn packet(&self) -> Packet {
 		unsafe {
 			Packet {
-				duration: av_frame_get_pkt_duration(self.ptr) as i64,
-				position: av_frame_get_pkt_pos(self.ptr) as i64,
-				size:     av_frame_get_pkt_size(self.ptr) as usize,
+				duration: av_frame_get_pkt_duration(self.as_ptr()) as i64,
+				position: av_frame_get_pkt_pos(self.as_ptr()) as i64,
+				size:     av_frame_get_pkt_size(self.as_ptr()) as usize,
 
-				pts: (*self.ptr).pkt_pts,
-				dts: (*self.ptr).pkt_dts,
+				pts: (*self.as_ptr()).pkt_pts,
+				dts: (*self.as_ptr()).pkt_dts,
 			}
 		}
 	}
 
 	pub fn pts(&self) -> i64 {
 		unsafe {
-			(*self.ptr).pts as i64
+			(*self.as_ptr()).pts as i64
 		}
 	}
 
 	pub fn timestamp(&self) -> Option<i64> {
 		unsafe {
-			match av_frame_get_best_effort_timestamp(self.ptr) {
+			match av_frame_get_best_effort_timestamp(self.as_ptr()) {
 				AV_NOPTS_VALUE => None,
 				t              => Some(t as i64)
 			}
@@ -72,31 +92,31 @@ impl Frame {
 
 	pub fn quality(&self) -> usize {
 		unsafe {
-			(*self.ptr).quality as usize
+			(*self.as_ptr()).quality as usize
 		}
 	}
 
 	pub fn flags(&self) -> Flags {
 		unsafe {
-			Flags::from_bits_truncate((*self.ptr).flags)
+			Flags::from_bits_truncate((*self.as_ptr()).flags)
 		}
 	}
 
 	pub fn metadata(&self) -> Dictionary {
 		unsafe {
-			Dictionary::wrap(av_frame_get_metadata(self.ptr))
+			Dictionary::wrap(av_frame_get_metadata(self.as_ptr()))
 		}
 	}
 
-	pub fn set_metadata(&mut self, mut value: Dictionary) {
+	pub fn set_metadata(&mut self, value: Dictionary) {
 		unsafe {
-			av_frame_set_metadata(self.ptr, value.take());
+			av_frame_set_metadata(self.as_mut_ptr(), value.take());
 		}
 	}
 
 	pub fn side_data(&self, kind: side_data::Type) -> Option<SideData> {
 		unsafe {
-			let ptr = av_frame_get_side_data(self.ptr, kind.into());
+			let ptr = av_frame_get_side_data(self.as_ptr(), kind.into());
 
 			if ptr == ptr::null_mut() {
 				None
@@ -109,7 +129,7 @@ impl Frame {
 
 	pub fn new_side_data(&mut self, kind: side_data::Type, size: usize) -> Option<SideData> {
 		unsafe {
-			let ptr = av_frame_new_side_data(self.ptr, kind.into(), size as c_int);
+			let ptr = av_frame_new_side_data(self.as_mut_ptr(), kind.into(), size as c_int);
 
 			if ptr == ptr::null_mut() {
 				None
@@ -122,7 +142,7 @@ impl Frame {
 
 	pub fn remove_side_data(&mut self, kind: side_data::Type) {
 		unsafe {
-			av_frame_remove_side_data(self.ptr, kind.into());
+			av_frame_remove_side_data(self.as_mut_ptr(), kind.into());
 		}
 	}
 }
@@ -132,7 +152,7 @@ unsafe impl Send for Frame { }
 impl Drop for Frame {
 	fn drop(&mut self) {
 		unsafe {
-			av_frame_free(&mut self.ptr);
+			av_frame_free(&mut self.as_mut_ptr());
 		}
 	}
 }