Revert "Make cfzlib the default on platforms that support it"

This reverts commit 2702145f3f.

cfzlib seems to have a MASSIVE memory leak in it. Trying to use it
when processing many files at once will cause your system to run out
of memory.

Closes #125

.travis.yml

@@ -11,7 +11,7 @@ matrix:
       env: TARGET=x86_64-apple-darwin
       cache: cargo
     - os: linux
-      rust: 1.27.0
+      rust: 1.24.0
       env: TARGET=x86_64-unknown-linux-gnu
       cache: cargo
     - os: linux

Cargo.toml

@@ -48,6 +48,7 @@ optional = true
 version = "1.0.1"
 
 [dependencies.cloudflare-zlib-sys]
+optional = true
 version = "^0.1.2"
 
 [dependencies.image]
@@ -62,10 +63,11 @@ binary = [
 ]
 default = ["binary", "parallel"]
 parallel = ["rayon"]
+cfzlib = ["cloudflare-zlib-sys"]
 dev = [
     "nightly-binary",
 ]
-nightly = []
+nightly = ["cfzlib"]
 nightly-binary = [
     "binary",
     "nightly",

README.md

@@ -26,7 +26,7 @@ cargo build --release
 cp target/release/oxipng /usr/local/bin
 ```
 
-The current minimum supported Rust version is **1.27.0**. Oxipng may compile on earlier versions of Rust,
+The current minimum supported Rust version is **1.24.0**. Oxipng may compile on earlier versions of Rust,
 but there is no guarantee.
 
 Oxipng follows Semantic Versioning.

README.template.md

@@ -26,7 +26,7 @@ cargo build --release
 cp target/release/oxipng /usr/local/bin
 ```
 
-The current minimum supported Rust version is **1.27.0**. Oxipng may compile on earlier versions of Rust,
+The current minimum supported Rust version is **1.24.0**. Oxipng may compile on earlier versions of Rust,
 but there is no guarantee.
 
 Oxipng follows Semantic Versioning.

src/deflate/mod.rs

@@ -21,13 +21,17 @@ pub fn deflate(
     zw: u8,
     max_size: &AtomicMin,
 ) -> Result<Vec<u8>, PngError> {
-    if is_cfzlib_supported() {
-        return cfzlib_deflate(data, zc, zs, zw, max_size);
+    #[cfg(feature = "cfzlib")]
+    {
+        if is_cfzlib_supported() {
+            return cfzlib_deflate(data, zc, zs, zw, max_size);
+        }
     }
 
     miniz_stream::compress_to_vec_oxipng(data, zc, zw.into(), zs.into(), max_size)
 }
 
+#[cfg(feature = "cfzlib")]
 fn is_cfzlib_supported() -> bool {
     #[cfg(target_arch = "x86_64")]
     {
@@ -44,6 +48,7 @@ fn is_cfzlib_supported() -> bool {
     false
 }
 
+#[cfg(feature = "cfzlib")]
 pub fn cfzlib_deflate(
     data: &[u8],
     level: u8,

src/lib.rs

@@ -1,5 +1,6 @@
 extern crate bit_vec;
 extern crate byteorder;
+#[cfg(feature = "cfzlib")]
 extern crate cloudflare_zlib_sys;
 extern crate crc;
 extern crate image;