Merge pull request #101 from lovasoa/efficient_skip_bytes

Avoid allocating a buffer and filling it just for skipping bytes

Author: kaksmet

src/parser.rs

@@ -3,7 +3,7 @@ use error::{Error, Result};
 use huffman::{HuffmanTable, HuffmanTableClass};
 use marker::Marker;
 use marker::Marker::*;
-use std::io::Read;
+use std::io::{self, Read};
 use std::ops::Range;
 
 #[derive(Clone, Copy, Debug, PartialEq)]
@@ -93,10 +93,14 @@ fn read_length<R: Read>(reader: &mut R, marker: Marker) -> Result<usize> {
 }
 
 fn skip_bytes<R: Read>(reader: &mut R, length: usize) -> Result<()> {
-    let mut buffer = vec![0u8; length];
-    reader.read_exact(&mut buffer)?;
-
-    Ok(())
+    let length = length as u64;
+    let to_skip = &mut reader.by_ref().take(length);
+    let copied = io::copy(to_skip, &mut io::sink())?;
+    if copied < length {
+        Err(Error::Io(io::ErrorKind::UnexpectedEof.into()))
+    } else {
+        Ok(())
+    }
 }
 
 // Section B.2.2