openpgp, buffered-reader: Make compression an optional feature.

  - This helps to reduce the trusted computing base if compression is
    not needed.

  - This makes it easier to fuzz Sequoia, previously the fuzzer was
    doing a great job creating compression bombs that triggered the
    fuzzers timeout.

  - Currently, the cargo workspace feature does not propagate
    --no-default-features, but it is possible to depend on the openpgp
    crate with `default-features = false`.

  - Unfortunately, a lot of test cases include compressed packages.
    This change conditionally disables these tests.

16 files changed, 403 insertions, 315 deletions

diff --git a/buffered-reader/Cargo.toml b/buffered-reader/Cargo.toml
index 68f4c60d..1702ac97 100644
--- a/buffered-reader/Cargo.toml
+++ b/buffered-reader/Cargo.toml
@@ -4,5 +4,13 @@ version = "0.1.0"
 authors = ["Neal H. Walfield <neal@gnu.org>"]
 
 [dependencies]
-bzip2 = "0.3.2"
-flate2 = "1.0.1"
+bzip2 = { version = "0.3.2", optional = true }
+flate2 = { version = "1.0.1", optional = true }
+
+[features]
+default = ["compression"]
+
+# The compression algorithms.
+compression = ["compression-deflate", "compression-bzip2"]
+compression-deflate = ["flate2"]
+compression-bzip2 = ["bzip2"]
diff --git a/buffered-reader/src/decompress_bzip2.rs b/buffered-reader/src/decompress_bzip2.rs
new file mode 100644
index 00000000..41fba37a
--- /dev/null
+++ b/buffered-reader/src/decompress_bzip2.rs
@@ -0,0 +1,118 @@
+use std::io;
+use std::fmt;
+
+use bzip2::read::BzDecoder;
+
+use super::*;
+
+
+pub struct BufferedReaderBzip<R: BufferedReader<C>, C> {
+    reader: BufferedReaderGeneric<BzDecoder<R>, C>,
+}
+
+impl <R: BufferedReader<()>> BufferedReaderBzip<R, ()> {
+    /// Instantiate a new bzip decompression reader.  `reader` is
+    /// the source to wrap.
+    pub fn new(reader: R) -> Self {
+        Self::with_cookie(reader, ())
+    }
+}
+
+impl <R: BufferedReader<C>, C> BufferedReaderBzip<R, C> {
+    /// Like `new()`, but sets a cookie, which can be retrieved using
+    /// the `cookie_ref` and `cookie_mut` methods, and set using
+    /// the `cookie_set` method.
+    pub fn with_cookie(reader: R, cookie: C) -> Self {
+        BufferedReaderBzip {
+            reader: BufferedReaderGeneric::with_cookie(
+                BzDecoder::new(reader), None, cookie),
+        }
+    }
+}
+
+impl<R: BufferedReader<C>, C> io::Read for BufferedReaderBzip<R, C> {
+    fn read(&mut self, buf: &mut [u8]) -> Result<usize, io::Error> {
+        self.reader.read(buf)
+    }
+}
+
+impl <R: BufferedReader<C>, C> fmt::Debug for BufferedReaderBzip<R, C> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("BufferedReaderBzip")
+            .field("reader", &self.get_ref().unwrap())
+            .finish()
+    }
+}
+
+impl<R: BufferedReader<C>, C> BufferedReader<C> for BufferedReaderBzip<R, C> {
+    fn buffer(&self) -> &[u8] {
+        return self.reader.buffer();
+    }
+
+    fn data(&mut self, amount: usize) -> Result<&[u8], io::Error> {
+        return self.reader.data(amount);
+    }
+
+    fn data_hard(&mut self, amount: usize) -> Result<&[u8], io::Error> {
+        return self.reader.data_hard(amount);
+    }
+
+    fn data_eof(&mut self) -> Result<&[u8], io::Error> {
+        return self.reader.data_eof();
+    }
+
+    fn consume(&mut self, amount: usize) -> &[u8] {
+        return self.reader.consume(amount);
+    }
+
+    fn data_consume(&mut self, amount: usize)
+                    -> Result<&[u8], io::Error> {
+        return self.reader.data_consume(amount);
+    }
+
+    fn data_consume_hard(&mut self, amount: usize) -> Result<&[u8], io::Error> {
+        return self.reader.data_consume_hard(amount);
+    }
+
+    fn read_be_u16(&mut self) -> Result<u16, io::Error> {
+        return self.reader.read_be_u16();
+    }
+
+    fn read_be_u32(&mut self) -> Result<u32, io::Error> {
+        return self.reader.read_be_u32();
+    }
+
+    fn steal(&mut self, amount: usize) -> Result<Vec<u8>, io::Error> {
+        return self.reader.steal(amount);
+    }
+
+    fn steal_eof(&mut self) -> Result<Vec<u8>, io::Error> {
+        return self.reader.steal_eof();
+    }
+
+    fn get_mut(&mut self) -> Option<&mut BufferedReader<C>> {
+        Some(self.reader.reader.get_mut())
+    }
+
+    fn get_ref(&self) -> Option<&BufferedReader<C>> {
+        Some(self.reader.reader.get_ref())
+    }
+
+    fn into_inner<'b>(self: Box<Self>)
+            -> Option<Box<BufferedReader<C> + 'b>> where Self: 'b {
+        // Strip the outer box.
+        Some(Box::new(self.reader.reader.into_inner()))
+    }
+
+    fn cookie_set(&mut self, cookie: C) -> C {
+        self.reader.cookie_set(cookie)
+    }
+
+    fn cookie_ref(&self) -> &C {
+        self.reader.cookie_ref()
+    }
+
+    fn cookie_mut(&mut self) -> &mut C {
+        self.reader.cookie_mut()
+    }
+}
diff --git a/buffered-reader/src/decompress.rs b/buffered-reader/src/decompress_deflate.rs
index 376edd06..c46b9eea 100644
--- a/buffered-reader/src/decompress.rs
+++ b/buffered-reader/src/decompress_deflate.rs
@@ -3,7 +3,6 @@ use std::fmt;
 
 use flate2::read::DeflateDecoder;
 use flate2::read::ZlibDecoder;
-use bzip2::read::BzDecoder;
 
 use super::*;
 
@@ -230,117 +229,6 @@ impl<R: BufferedReader<C>, C> BufferedReader<C>
         self.reader.cookie_mut()
     }
 }
-
-pub struct BufferedReaderBzip<R: BufferedReader<C>, C> {
-    reader: BufferedReaderGeneric<BzDecoder<R>, C>,
-}
-
-impl <R: BufferedReader<()>> BufferedReaderBzip<R, ()> {
-    /// Instantiate a new bzip decompression reader.  `reader` is
-    /// the source to wrap.
-    pub fn new(reader: R) -> Self {
-        Self::with_cookie(reader, ())
-    }
-}
-
-impl <R: BufferedReader<C>, C> BufferedReaderBzip<R, C> {
-    /// Like `new()`, but sets a cookie, which can be retrieved using
-    /// the `cookie_ref` and `cookie_mut` methods, and set using
-    /// the `cookie_set` method.
-    pub fn with_cookie(reader: R, cookie: C) -> Self {
-        BufferedReaderBzip {
-            reader: BufferedReaderGeneric::with_cookie(
-                BzDecoder::new(reader), None, cookie),
-        }
-    }
-}
-
-impl<R: BufferedReader<C>, C> io::Read for BufferedReaderBzip<R, C> {
-    fn read(&mut self, buf: &mut [u8]) -> Result<usize, io::Error> {
-        self.reader.read(buf)
-    }
-}
-
-impl <R: BufferedReader<C>, C> fmt::Debug for BufferedReaderBzip<R, C> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_struct("BufferedReaderBzip")
-            .field("reader", &self.get_ref().unwrap())
-            .finish()
-    }
-}
-
-impl<R: BufferedReader<C>, C> BufferedReader<C> for BufferedReaderBzip<R, C> {
-    fn buffer(&self) -> &[u8] {
-        return self.reader.buffer();
-    }
-
-    fn data(&mut self, amount: usize) -> Result<&[u8], io::Error> {
-        return self.reader.data(amount);
-    }
-
-    fn data_hard(&mut self, amount: usize) -> Result<&[u8], io::Error> {
-        return self.reader.data_hard(amount);
-    }
-
-    fn data_eof(&mut self) -> Result<&[u8], io::Error> {
-        return self.reader.data_eof();
-    }
-
-    fn consume(&mut self, amount: usize) -> &[u8] {
-        return self.reader.consume(amount);
-    }
-
-    fn data_consume(&mut self, amount: usize)
-                    -> Result<&[u8], io::Error> {
-        return self.reader.data_consume(amount);
-    }
-
-    fn data_consume_hard(&mut self, amount: usize) -> Result<&[u8], io::Error> {
-        return self.reader.data_consume_hard(amount);
-    }
-
-    fn read_be_u16(&mut self) -> Result<u16, io::Error> {
-        return self.reader.read_be_u16();
-    }
-
-    fn read_be_u32(&mut self) -> Result<u32, io::Error> {
-        return self.reader.read_be_u32();
-    }
-
-    fn steal(&mut self, amount: usize) -> Result<Vec<u8>, io::Error> {
-        return self.reader.steal(amount);
-    }
-
-    fn steal_eof(&mut self) -> Result<Vec<u8>, io::Error> {
-        return self.reader.steal_eof();
-    }
-
-    fn get_mut(&mut self) -> Option<&mut BufferedReader<C>> {
-        Some(self.reader.reader.get_mut())
-    }
-
-    fn get_ref(&self) -> Option<&BufferedReader<C>> {
-        Some(self.reader.reader.get_ref())
-    }
-
-    fn into_inner<'b>(self: Box<Self>)
-            -> Option<Box<BufferedReader<C> + 'b>> where Self: 'b {
-        // Strip the outer box.
-        Some(Box::new(self.reader.reader.into_inner()))
-    }
-
-    fn cookie_set(&mut self, cookie: C) -> C {
-        self.reader.cookie_set(cookie)
-    }
-
-    fn cookie_ref(&self) -> &C {
-        self.reader.cookie_ref()
-    }
-
-    fn cookie_mut(&mut self) -> &mut C {
-        self.reader.cookie_mut()
-    }
-}
 
 #[cfg(test)]
 mod test {
diff --git a/buffered-reader/src/lib.rs b/buffered-reader/src/lib.rs
index ab19fa37..9619e0de 100644
--- a/buffered-reader/src/lib.rs
+++ b/buffered-reader/src/lib.rs
@@ -1,6 +1,8 @@
 //! An improved `BufRead` interface.
 
+#[cfg(feature = "compression-deflate")]
 extern crate flate2;
+#[cfg(feature = "compression-bzip2")]
 extern crate bzip2;
 
 use std::io;
@@ -13,16 +15,22 @@ mod memory;
 mod limitor;
 mod dup;
 mod eof;
-mod decompress;
+#[cfg(feature = "compression-deflate")]
+mod decompress_deflate;
+#[cfg(feature = "compression-bzip2")]
+mod decompress_bzip2;
 
 pub use self::generic::BufferedReaderGeneric;
 pub use self::memory::BufferedReaderMemory;
 pub use self::limitor::BufferedReaderLimitor;
 pub use self::dup::BufferedReaderDup;
 pub use self::eof::BufferedReaderEOF;
-pub use self::decompress::BufferedReaderDeflate;
-pub use self::decompress::BufferedReaderZlib;
-pub use self::decompress::BufferedReaderBzip;
+#[cfg(feature = "compression-deflate")]
+pub use self::decompress_deflate::BufferedReaderDeflate;
+#[cfg(feature = "compression-deflate")]
+pub use self::decompress_deflate::BufferedReaderZlib;
+#[cfg(feature = "compression-bzip2")]
+pub use self::decompress_bzip2::BufferedReaderBzip;
 
 // The default buffer size.
 const DEFAULT_BUF_SIZE: usize = 8 * 1024;
diff --git a/openpgp/Cargo.toml b/openpgp/Cargo.toml
index 3d2d4c31..acf33a3c 100644
--- a/openpgp/Cargo.toml
+++ b/openpgp/Cargo.toml
@@ -4,11 +4,19 @@ version = "0.1.0"
 authors = ["Neal H. Walfield <neal@gnu.org>"]
 
 [dependencies]
-buffered-reader = { path = "../buffered-reader" }
+buffered-reader = { path = "../buffered-reader", default-features = false }
 base64 = "0.9.0"
-bzip2 = "0.3.2"
+bzip2 = { version = "0.3.2", optional = true }
 failure = "0.1.1"
-flate2 = "1.0.1"
+flate2 = { version = "1.0.1", optional = true }
 nettle = { git = "https://gitlab.com/sequoia-pgp/nettle-rs.git" }
 quickcheck = "0.6"
 time = "0.1.38"
+
+[features]
+default = ["compression"]
+
+# The compression algorithms.
+compression = ["compression-deflate", "compression-bzip2"]
+compression-deflate = ["flate2", "buffered-reader/compression-deflate"]
+compression-bzip2 = ["bzip2", "buffered-reader/compression-bzip2"]
diff --git a/openpgp/src/lib.rs b/openpgp/src/lib.rs
index 8bfd504e..af011720 100644
--- a/openpgp/src/lib.rs
+++ b/openpgp/src/lib.rs
@@ -45,7 +45,9 @@ extern crate buffered_reader;
 
 extern crate nettle;
 
+#[cfg(feature = "compression-deflate")]
 extern crate flate2;
+#[cfg(feature = "compression-bzip2")]
 extern crate bzip2;
 
 #[cfg(test)]
diff --git a/openpgp/src/packet_pile.rs b/openpgp/src/packet_pile.rs
index 55851fb1..65ca1b79 100644
--- a/openpgp/src/packet_pile.rs
+++ b/openpgp/src/packet_pile.rs
@@ -27,6 +27,7 @@ macro_rules! bytes {
 use std::path::PathBuf;
 
 #[cfg(test)]
+#[allow(dead_code)]
 fn path_to(artifact: &str) -> PathBuf {
     [env!("CARGO_MANIFEST_DIR"), "tests", "data", "messages", artifact]
         .iter().collect()
@@ -434,8 +435,6 @@ mod message_test {
     use SEIP;
     use packet::Tag;
 
-    use std::io::Read;
-
     #[test]
     fn deserialize_test_1 () {
         // XXX: This test should be more thorough.  Right now, we mostly
@@ -456,6 +455,7 @@ mod message_test {
         assert_eq!(count, 61);
     }
 
+    #[cfg(feature = "compression-deflate")]
     #[test]
     fn deserialize_test_2 () {
         // A message containing a compressed packet that contains a
@@ -474,6 +474,7 @@ mod message_test {
         assert_eq!(count, 2);
     }
 
+    #[cfg(feature = "compression-deflate")]
     #[test]
     fn deserialize_test_3 () {
         let path = path_to("signed.gpg");
@@ -526,6 +527,7 @@ mod message_test {
         assert_eq!(pile.children().len(), 77);
     }
 
+    #[cfg(feature = "compression-deflate")]
     #[test]
     fn compression_quine_test_1 () {
         // Use the PacketPile::from_file interface to parse an OpenPGP
@@ -547,6 +549,7 @@ mod message_test {
         assert_eq!(count, 1 + max_recursion_depth);
     }
 
+    #[cfg(feature = "compression-deflate")]
     #[test]
     fn compression_quine_test_2 () {
         // Use the iterator interface to parse an OpenPGP quine.
@@ -577,8 +580,10 @@ mod message_test {
         assert_eq!(count, 1 + max_recursion_depth as usize);
     }
 
+    #[cfg(feature = "compression-deflate")]
     #[test]
     fn consume_content_1 () {
+        use std::io::Read;
         // A message containing a compressed packet that contains a
         // literal packet.  When we read some of the compressed
         // packet, we expect recurse() to not recurse.
diff --git a/openpgp/src/parse/packet_pile_parser.rs b/openpgp/src/parse/packet_pile_parser.rs
index 3d48a8b0..f19deb81 100644
--- a/openpgp/src/parse/packet_pile_parser.rs
+++ b/openpgp/src/parse/packet_pile_parser.rs
@@ -13,6 +13,7 @@ use buffered_reader::{BufferedReader, BufferedReaderGeneric,
                       BufferedReaderMemory};
 
 #[cfg(test)]
+#[allow(unused_macros)]
 macro_rules! bytes {
     ( $x:expr ) => { include_bytes!(concat!("../../tests/data/messages/", $x)) };
 }
@@ -282,6 +283,7 @@ fn message_parser_test() {
 
 // Check that we can use the read interface to stream the contents of
 // a packet.
+#[cfg(feature = "compression-deflate")]
 #[test]
 fn message_parser_reader_interface() {
     use std::io::Read;
diff --git a/openpgp/src/parse/parse.rs b/openpgp/src/parse/parse.rs
index 1b431b3d..145ace09 100644
--- a/openpgp/src/parse/parse.rs
+++ b/openpgp/src/parse/parse.rs
@@ -1122,11 +1122,19 @@ impl CompressedData {
                       php.recursion_depth);
         }
 
+        #[allow(unreachable_patterns)]
         match algo {
+            CompressionAlgorithm::Uncompressed => (),
+            #[cfg(feature = "compression-deflate")]
+            CompressionAlgorithm::Zip
+                | CompressionAlgorithm::Zlib => (),
+            #[cfg(feature = "compression-bzip2")]
+            CompressionAlgorithm::BZip2 => (),
             CompressionAlgorithm::Unknown(_)
             | CompressionAlgorithm::Private(_) =>
                 return php.fail("unknown compression algorithm"),
-            _ => (),
+            _ =>
+                return php.fail("unsupported compression algorithm"),
         }
 
         let recursion_depth = php.recursion_depth as usize;
@@ -1143,14 +1151,18 @@ impl CompressedData {
                                for a compression filter: this is an \
                                \"uncompressed compression packet\".");
                 }
+                let _ = recursion_depth;
                 reader
             },
+            #[cfg(feature = "compression-deflate")]
             CompressionAlgorithm::Zip =>
                 Box::new(BufferedReaderDeflate::with_cookie(
                     reader, Cookie::new(recursion_depth))),
+            #[cfg(feature = "compression-deflate")]
             CompressionAlgorithm::Zlib =>
                 Box::new(BufferedReaderZlib::with_cookie(
                     reader, Cookie::new(recursion_depth))),
+            #[cfg(feature = "compression-bzip2")]
             CompressionAlgorithm::BZip2 =>
                 Box::new(BufferedReaderBzip::with_cookie(
                     reader, Cookie::new(recursion_depth))),
@@ -1162,11 +1174,19 @@ impl CompressedData {
     }
 }
 
+#[cfg(any(feature = "compression-deflate", feature = "compression-bzip2"))]
 #[test]
 fn compressed_data_parser_test () {
     let expected = bytes!("a-cypherpunks-manifesto.txt");
 
     for i in 1..4 {
+        match CompressionAlgorithm::from(i) {
+            #[cfg(feature = "compression-deflate")]
+            CompressionAlgorithm::Zip | CompressionAlgorithm::Zlib => (),
+            #[cfg(feature = "compression-bzip2")]
+            CompressionAlgorithm::BZip2 => (),
+            _ => continue,
+        }
         let path = path_to(&format!("compressed-data-algo-{}.gpg", i)[..]);
         let mut pp = PacketParser::from_file(path).unwrap().unwrap();
 
@@ -2591,6 +2611,7 @@ impl<'a> BufferedReader<Cookie> for PacketParser<'a> {
 
 // Check that we can use the read interface to stream the contents of
 // a packet.
+#[cfg(feature = "compression-deflate")]
 #[test]
 fn packet_parser_reader_interface() {
     // We need the Read trait.
diff --git a/openpgp/src/parse/subpacket.rs b/openpgp/src/parse/subpacket.rs
index 3d8b612a..0c58d76c 100644
--- a/openpgp/src/parse/subpacket.rs
+++ b/openpgp/src/parse/subpacket.rs
@@ -1480,6 +1480,7 @@ impl Signature {
     }
 }
 
+#[cfg(feature = "compression-deflate")]
 #[test]
 fn subpacket_test_1 () {
     use PacketPile;
diff --git a/openpgp/src/serialize/mod.rs b/openpgp/src/serialize/mod.rs
index 298536a2..01d51479 100644
--- a/openpgp/src/serialize/mod.rs
+++ b/openpgp/src/serialize/mod.rs
@@ -1034,6 +1034,7 @@ mod serialize_test {
 
     }
 
+    #[cfg(feature = "compression-deflate")]
     #[test]
     fn serialize_test_2() {
         // Given a packet in serialized form:
diff --git a/openpgp/src/serialize/stream.rs b/openpgp/src/serialize/stream.rs
index 1434b677..012ceca8 100644
--- a/openpgp/src/serialize/stream.rs
+++ b/openpgp/src/serialize/stream.rs
@@ -542,10 +542,13 @@ impl<'a> Compressor<'a> {
         let inner: writer::Stack<'a, Cookie> = match algo {
             CompressionAlgorithm::Uncompressed =>
                 writer::Identity::new(inner, Cookie::new(level)),
+            #[cfg(feature = "compression-deflate")]
             CompressionAlgorithm::Zip =>
                 writer::ZIP::new(inner, Cookie::new(level)),
+            #[cfg(feature = "compression-deflate")]
             CompressionAlgorithm::Zlib =>
                 writer::ZLIB::new(inner, Cookie::new(level)),
+            #[cfg(feature = "compression-bzip2")]
             CompressionAlgorithm::BZip2 =>
                 writer::BZ::new(inner, Cookie::new(level)),
             _ => unimplemented!(),
@@ -1045,6 +1048,7 @@ mod test {
         }
     }
 
+    #[cfg(feature = "compression-deflate")]
     #[test]
     fn stream_big() {
         let mut zeros = Vec::<u8>::new();
diff --git a/openpgp/src/serialize/writer.rs b/openpgp/src/serialize/writer/mod.rs
index 628187d1..39d21bcd 100644
--- a/openpgp/src/serialize/writer.rs
+++ b/openpgp/src/serialize/writer/mod.rs
@@ -1,9 +1,14 @@
 //! Stackable writers.
 
-use bzip2::Compression as BzCompression;
-use bzip2::write::BzEncoder;
-use flate2::Compression as FlateCompression;
-use flate2::write::{DeflateEncoder, ZlibEncoder};
+#[cfg(feature = "compression-bzip2")]
+mod writer_bzip2;
+#[cfg(feature = "compression-bzip2")]
+pub use self::writer_bzip2::BZ;
+#[cfg(feature = "compression-deflate")]
+mod writer_deflate;
+#[cfg(feature = "compression-deflate")]
+pub use self::writer_deflate::{ZIP, ZLIB};
+
 use std::fmt;
 use std::io;
 
@@ -280,188 +285,6 @@ impl<'a, W: io::Write, C> Stackable<'a, C> for Generic<W, C> {
     }
 }
 
-/// ZIPing writer.
-pub struct ZIP<'a, C> {
-    inner: Generic<DeflateEncoder<Stack<'a, C>>, C>,
-}
-
-impl<'a, C> ZIP<'a, C> {
-    pub fn new(inner: Stack<'a, C>, cookie: C) -> Box<Self> {
-        Box::new(ZIP {
-            inner: Generic::new_unboxed(
-                DeflateEncoder::new(inner, FlateCompression::default()),
-                cookie),
-        })
-    }
-}
-
-impl<'a, C:> fmt::Debug for ZIP<'a, C> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_struct("writer::ZIP")
-            .field("inner", &self.inner)
-            .finish()
-    }
-}
-
-impl<'a, C> io::Write for ZIP<'a, C> {
-    fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
-        self.inner.write(bytes)
-    }
-
-    fn flush(&mut self) -> io::Result<()> {
-        self.inner.flush()
-    }
-}
-
-impl<'a, C> Stackable<'a, C> for ZIP<'a, C> {
-    fn into_inner(self: Box<Self>) -> Result<Option<Stack<'a, C>>> {
-        let inner = self.inner.inner.finish()?;
-        Ok(Some(inner))
-    }
-    fn pop(&mut self) -> Result<Option<Stack<'a, C>>> {
-        unimplemented!()
-    }
-    fn mount(&mut self, _new: Stack<'a, C>) {
-        unimplemented!()
-    }
-    fn inner_mut(&mut self) -> Option<&mut Stackable<'a, C>> {
-        self.inner.inner_mut()
-    }
-    fn inner_ref(&self) -> Option<&Stackable<'a, C>> {
-        self.inner.inner_ref()
-    }
-    fn cookie_set(&mut self, cookie: C) -> C {
-        self.inner.cookie_set(cookie)
-    }
-    fn cookie_ref(&self) -> &C {
-        self.inner.cookie_ref()
-    }
-    fn cookie_mut(&mut self) -> &mut C {
-        self.inner.cookie_mut()
-    }
-}
-
-/// ZLIBing writer.
-pub struct ZLIB<'a, C> {
-    inner: Generic<ZlibEncoder<Stack<'a, C>>, C>,
-}
-
-impl<'a, C> ZLIB<'a, C> {
-    pub fn new(inner: Stack<'a, C>, cookie: C) -> Box<Self> {
-        Box::new(ZLIB {
-            inner: Generic::new_unboxed(
-                ZlibEncoder::new(inner, FlateCompression::default()),
-                cookie),
-        })
-    }
-}
-
-impl<'a, C:> fmt::Debug for ZLIB<'a, C> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_struct("writer::ZLIB")
-            .field("inner", &self.inner)
-            .finish()
-    }
-}
-
-impl<'a, C> io::Write for ZLIB<'a, C> {
-    fn write(&mut self, bytes: &[u8]) -> io::Result<usize> {
-        self.inner.write(bytes)
-    }
-
-    fn flush(&mut self) -> io::Result<()> {
-        self.inner.flush()
-    }
-}
-
-impl<'a, C> Stackable<'a, C> for ZLIB<'a, C> {
-    fn into_inner(sel