Add tests for reading with an empty buffer, and fix bug in GzDecoder

src/gz/bufread.rs

@@ -358,6 +358,9 @@ impl<R: BufRead> Read for GzDecoder<R> {
             let another_error = io::ErrorKind::Other.into();
             return Err(mem::replace(e, another_error));
         }
+        if into.is_empty() {
+            return Ok(0);
+        }
         match try!(self.inner.read(into)) {
             0 => {
                 try!(self.finish());

tests/empty-read.rs

@@ -0,0 +1,81 @@
+extern crate flate2;
+
+use std::io::{Read, Write};
+
+#[test]
+fn deflate_decoder_empty_read() {
+    let original: &[u8] = b"Lorem ipsum dolor sit amet.";
+    let mut encoder = flate2::write::DeflateEncoder::new(Vec::new(), flate2::Compression::default());
+    encoder.write_all(original).unwrap();
+    let encoded: Vec<u8> = encoder.finish().unwrap();
+    let mut decoder = flate2::read::DeflateDecoder::new(encoded.as_slice());
+    assert_eq!(decoder.read(&mut []).unwrap(), 0);
+    let mut decoded = Vec::new();
+    decoder.read_to_end(&mut decoded).unwrap();
+    assert_eq!(decoded.as_slice(), original);
+}
+
+#[test]
+fn deflate_encoder_empty_read() {
+    let original: &[u8] = b"Lorem ipsum dolor sit amet.";
+    let mut encoder = flate2::read::DeflateEncoder::new(original, flate2::Compression::default());
+    assert_eq!(encoder.read(&mut []).unwrap(), 0);
+    let mut encoded = Vec::new();
+    encoder.read_to_end(&mut encoded).unwrap();
+    let mut decoder = flate2::read::DeflateDecoder::new(encoded.as_slice());
+    let mut decoded = Vec::new();
+    decoder.read_to_end(&mut decoded).unwrap();
+    assert_eq!(decoded.as_slice(), original);
+}
+
+#[test]
+fn gzip_decoder_empty_read() {
+    let original: &[u8] = b"Lorem ipsum dolor sit amet.";
+    let mut encoder = flate2::write::GzEncoder::new(Vec::new(), flate2::Compression::default());
+    encoder.write_all(original).unwrap();
+    let encoded: Vec<u8> = encoder.finish().unwrap();
+    let mut decoder = flate2::read::GzDecoder::new(encoded.as_slice());
+    assert_eq!(decoder.read(&mut []).unwrap(), 0);
+    let mut decoded = Vec::new();
+    decoder.read_to_end(&mut decoded).unwrap();
+    assert_eq!(decoded.as_slice(), original);
+}
+
+#[test]
+fn gzip_encoder_empty_read() {
+    let original: &[u8] = b"Lorem ipsum dolor sit amet.";
+    let mut encoder = flate2::read::GzEncoder::new(original, flate2::Compression::default());
+    assert_eq!(encoder.read(&mut []).unwrap(), 0);
+    let mut encoded = Vec::new();
+    encoder.read_to_end(&mut encoded).unwrap();
+    let mut decoder = flate2::read::GzDecoder::new(encoded.as_slice());
+    let mut decoded = Vec::new();
+    decoder.read_to_end(&mut decoded).unwrap();
+    assert_eq!(decoded.as_slice(), original);
+}
+
+#[test]
+fn zlib_decoder_empty_read() {
+    let original: &[u8] = b"Lorem ipsum dolor sit amet.";
+    let mut encoder = flate2::write::ZlibEncoder::new(Vec::new(), flate2::Compression::default());
+    encoder.write_all(original).unwrap();
+    let encoded: Vec<u8> = encoder.finish().unwrap();
+    let mut decoder = flate2::read::ZlibDecoder::new(encoded.as_slice());
+    assert_eq!(decoder.read(&mut []).unwrap(), 0);
+    let mut decoded = Vec::new();
+    decoder.read_to_end(&mut decoded).unwrap();
+    assert_eq!(decoded.as_slice(), original);
+}
+
+#[test]
+fn zlib_encoder_empty_read() {
+    let original: &[u8] = b"Lorem ipsum dolor sit amet.";
+    let mut encoder = flate2::read::ZlibEncoder::new(original, flate2::Compression::default());
+    assert_eq!(encoder.read(&mut []).unwrap(), 0);
+    let mut encoded = Vec::new();
+    encoder.read_to_end(&mut encoded).unwrap();
+    let mut decoder = flate2::read::ZlibDecoder::new(encoded.as_slice());
+    let mut decoded = Vec::new();
+    decoder.read_to_end(&mut decoded).unwrap();
+    assert_eq!(decoded.as_slice(), original);
+}