1 files changed, 84 insertions, 0 deletions
diff --git a/third_party/rust/scroll/src/error.rs b/third_party/rust/scroll/src/error.rs
new file mode 100644
index 0000000000..7740254774
--- /dev/null
+++ b/third_party/rust/scroll/src/error.rs
@@ -0,0 +1,84 @@
+use core::fmt::{self, Display};
+use core::result;
+
+#[cfg(feature = "std")]
+use std::error;
+#[cfg(feature = "std")]
+use std::io;
+
+#[derive(Debug)]
+/// A custom Scroll error
+pub enum Error {
+    /// The type you tried to read was too big
+    TooBig {
+        size: usize,
+        len: usize,
+    },
+    /// The requested offset to read/write at is invalid
+    BadOffset(usize),
+    BadInput {
+        size: usize,
+        msg: &'static str,
+    },
+    #[cfg(feature = "std")]
+    /// A custom Scroll error for reporting messages to clients
+    Custom(String),
+    #[cfg(feature = "std")]
+    /// Returned when IO based errors are encountered
+    IO(io::Error),
+}
+
+#[cfg(feature = "std")]
+impl error::Error for Error {
+    fn description(&self) -> &str {
+        match *self {
+            Error::TooBig { .. } => "TooBig",
+            Error::BadOffset(_) => "BadOffset",
+            Error::BadInput { .. } => "BadInput",
+            Error::Custom(_) => "Custom",
+            Error::IO(_) => "IO",
+        }
+    }
+    fn cause(&self) -> Option<&dyn error::Error> {
+        match *self {
+            Error::TooBig { .. } => None,
+            Error::BadOffset(_) => None,
+            Error::BadInput { .. } => None,
+            Error::Custom(_) => None,
+            Error::IO(ref io) => io.source(),
+        }
+    }
+}
+
+#[cfg(feature = "std")]
+impl From<io::Error> for Error {
+    fn from(err: io::Error) -> Error {
+        Error::IO(err)
+    }
+}
+
+impl Display for Error {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            Error::TooBig { ref size, ref len } => {
+                write!(fmt, "type is too big ({}) for {}", size, len)
+            }
+            Error::BadOffset(ref offset) => {
+                write!(fmt, "bad offset {}", offset)
+            }
+            Error::BadInput { ref msg, ref size } => {
+                write!(fmt, "bad input {} ({})", msg, size)
+            }
+            #[cfg(feature = "std")]
+            Error::Custom(ref msg) => {
+                write!(fmt, "{}", msg)
+            }
+            #[cfg(feature = "std")]
+            Error::IO(ref err) => {
+                write!(fmt, "{}", err)
+            }
+        }
+    }
+}
+
+pub type Result<T> = result::Result<T, Error>;