1 files changed, 49 insertions, 0 deletions
diff --git a/src/config/limit.rs b/src/config/limit.rs
new file mode 100644
index 0000000..4772298
--- /dev/null
+++ b/src/config/limit.rs
@@ -0,0 +1,49 @@
+use error::{ErrorKind, Result};
+
+/// A trait for stopping serialization and deserialization when a certain limit has been reached.
+pub trait SizeLimit {
+    /// Tells the SizeLimit that a certain number of bytes has been
+    /// read or written.  Returns Err if the limit has been exceeded.
+    fn add(&mut self, n: u64) -> Result<()>;
+    /// Returns the hard limit (if one exists)
+    fn limit(&self) -> Option<u64>;
+}
+
+/// A SizeLimit that restricts serialized or deserialized messages from
+/// exceeding a certain byte length.
+#[derive(Copy, Clone)]
+pub struct Bounded(pub u64);
+
+/// A SizeLimit without a limit!
+/// Use this if you don't care about the size of encoded or decoded messages.
+#[derive(Copy, Clone)]
+pub struct Infinite;
+
+impl SizeLimit for Bounded {
+    #[inline(always)]
+    fn add(&mut self, n: u64) -> Result<()> {
+        if self.0 >= n {
+            self.0 -= n;
+            Ok(())
+        } else {
+            Err(Box::new(ErrorKind::SizeLimit))
+        }
+    }
+
+    #[inline(always)]
+    fn limit(&self) -> Option<u64> {
+        Some(self.0)
+    }
+}
+
+impl SizeLimit for Infinite {
+    #[inline(always)]
+    fn add(&mut self, _: u64) -> Result<()> {
+        Ok(())
+    }
+
+    #[inline(always)]
+    fn limit(&self) -> Option<u64> {
+        None
+    }
+}