io: Do not panic in Drop impls

We do the memory unmapping in the Mmap Drop impl itself now, so we
can get rid of the Arena Drop impl completely.

In the Stream Drop impl, we ignore any errors returned by stop().

Signed-off-by: Christopher N. Hesse <[email protected]>

src/io/mod.rs

@@ -17,10 +17,7 @@ use crate::io::traits::{CaptureStream, OutputStream, Stream as StreamTrait};
 use crate::memory::{Memory, Mmap, UserPtr};
 use crate::v4l2;
 
-/// Manage mapped buffers
-///
-/// All buffers are unmapped in the Drop impl.
-/// In case of errors during unmapping, we panic because there is memory corruption going on.
+/// Manage memory buffers
 pub(crate) struct Arena<T> {
     handle: Arc<Handle>,
     pub bufs: Vec<Buffer<T>>,
@@ -49,30 +46,6 @@ impl<T> Arena<T> {
     }
 }
 
-impl<T> Drop for Arena<T> {
-    fn drop(&mut self) {
-        if self.bufs.is_empty() {
-            // nothing to do
-            return;
-        }
-
-        // free all buffers by requesting 0
-        if let Err(e) = self.request(0) {
-            if let Some(code) = e.raw_os_error() {
-                // ENODEV means the file descriptor wrapped in the handle became invalid, most
-                // likely because the device was unplugged or the connection (USB, PCI, ..)
-                // broke down. Handle this case gracefully by ignoring it.
-                if code == 19 {
-                    /* ignore */
-                    return;
-                }
-            }
-
-            panic!("{:?}", e)
-        }
-    }
-}
-
 impl<'a> Arena<Mmap<'a>> {
     /// Returns a new buffer manager instance
     ///
@@ -300,19 +273,7 @@ impl<T> Stream<T> {
 
 impl<T> Drop for Stream<T> {
     fn drop(&mut self) {
-        if let Err(e) = self.stop() {
-            if let Some(code) = e.raw_os_error() {
-                // ENODEV means the file descriptor wrapped in the handle became invalid, most
-                // likely because the device was unplugged or the connection (USB, PCI, ..)
-                // broke down. Handle this case gracefully by ignoring it.
-                if code == 19 {
-                    /* ignore */
-                    return;
-                }
-            }
-
-            panic!("{:?}", e)
-        }
+        let _ = self.stop();
     }
 }