1 files changed, 72 insertions, 0 deletions
diff --git a/third_party/rust/png/src/traits.rs b/third_party/rust/png/src/traits.rs
new file mode 100644
index 0000000000..fac36f3699
--- /dev/null
+++ b/third_party/rust/png/src/traits.rs
@@ -0,0 +1,72 @@
+use std::io;
+
+// Will be replaced by stdlib solution
+fn read_all<R: io::Read + ?Sized>(this: &mut R, buf: &mut [u8]) -> io::Result<()> {
+    let mut total = 0;
+    while total < buf.len() {
+        match this.read(&mut buf[total..]) {
+            Ok(0) => return Err(io::Error::new(io::ErrorKind::Other,
+                                               "failed to read the whole buffer")),
+            Ok(n) => total += n,
+            Err(ref e) if e.kind() == io::ErrorKind::Interrupted => {}
+            Err(e) => return Err(e),
+        }
+    }
+    Ok(())
+}
+
+/// Read extension to read big endian data
+pub trait ReadBytesExt<T>: io::Read {
+    /// Read `T` from a bytes stream. Most significant byte first.
+    fn read_be(&mut self) -> io::Result<T>;
+
+}
+
+/// Write extension to write big endian data
+pub trait WriteBytesExt<T>: io::Write {
+    /// Writes `T` to a bytes stream. Most significant byte first.
+    fn write_be(&mut self, _: T) -> io::Result<()>;
+
+}
+
+impl<W: io::Read + ?Sized> ReadBytesExt<u8> for W {
+	#[inline]
+	fn read_be(&mut self) -> io::Result<u8> {
+        let mut byte = [0];
+		read_all(self, &mut byte)?;
+        Ok(byte[0])
+	}
+}
+impl<W: io::Read + ?Sized> ReadBytesExt<u16> for W {
+	#[inline]
+	fn read_be(&mut self) -> io::Result<u16> {
+        let mut bytes = [0, 0];
+		read_all(self, &mut bytes)?;
+        Ok((u16::from(bytes[0])) << 8 | u16::from(bytes[1]))
+	}
+}
+
+impl<W: io::Read + ?Sized> ReadBytesExt<u32> for W {
+	#[inline]
+	fn read_be(&mut self) -> io::Result<u32> {
+        let mut bytes = [0, 0, 0, 0];
+		read_all(self, &mut bytes)?;
+        Ok(  (u32::from(bytes[0])) << 24 
+           | (u32::from(bytes[1])) << 16
+           | (u32::from(bytes[2])) << 8
+           |  u32::from(bytes[3])
+        )
+	}
+}
+
+impl<W: io::Write + ?Sized> WriteBytesExt<u32> for W {
+    #[inline]
+    fn write_be(&mut self, n: u32) -> io::Result<()> {
+        self.write_all(&[
+            (n >> 24) as u8,
+            (n >> 16) as u8,
+            (n >>  8) as u8,
+            n         as u8
+        ])
+    }
+}