revert libc removal

ethbloom/CHANGELOG.md

@@ -5,7 +5,6 @@ The format is based on [Keep a Changelog].
 [Keep a Changelog]: http://keepachangelog.com/en/1.0.0/
 
 ## [Unreleased]
-- Removed `libc` feature. [#317](https://github.com/paritytech/parity-common/pull/317)
 
 ## [0.8.1] - 2019-10-24
 ### Dependencies

ethbloom/Cargo.toml

@@ -22,9 +22,10 @@ rand = "0.7.2"
 hex-literal = "0.2.1"
 
 [features]
-default = ["std", "serialize", "rustc-hex"]
+default = ["std", "serialize", "libc", "rustc-hex"]
 std = ["fixed-hash/std", "crunchy/std"]
 serialize = ["std", "impl-serde"]
+libc = ["fixed-hash/libc"]
 rustc-hex = ["fixed-hash/rustc-hex"]
 
 [[bench]]

fixed-hash/CHANGELOG.md

@@ -5,7 +5,6 @@ The format is based on [Keep a Changelog].
 [Keep a Changelog]: http://keepachangelog.com/en/1.0.0/
 
 ## [Unreleased]
-- Removed `libc` feature. [#317](https://github.com/paritytech/parity-common/pull/317)
 
 ## [0.5.2] - 2019-12-19
 ### Fixed

fixed-hash/Cargo.toml

@@ -22,10 +22,13 @@ static_assertions = "1.0.0"
 
 [dev-dependencies]
 rand_xorshift = "0.2.0"
-criterion = "0.3.0"
+criterion = "0.3.1"
+
+[target.'cfg(not(target_os = "unknown"))'.dependencies]
+libc = { version = "0.2.65", optional = true, default-features = false }
 
 [features]
-default = ["std", "rand", "rustc-hex", "byteorder"]
+default = ["std", "libc", "rand", "rustc-hex", "byteorder"]
 std = ["rustc-hex/std", "rand/std", "byteorder/std"]
 
 api-dummy = [] # Feature used by docs.rs to display documentation of hash types

fixed-hash/src/hash.rs

@@ -313,7 +313,7 @@ macro_rules! construct_fixed_hash {
 
 		impl_byteorder_for_fixed_hash!($name);
 		impl_rand_for_fixed_hash!($name);
-		impl_cmp_for_fixed_hash!($name);
+		impl_libc_for_fixed_hash!($name);
 		impl_rustc_hex_for_fixed_hash!($name);
 		impl_quickcheck_for_fixed_hash!($name);
 	}
@@ -527,9 +527,17 @@ macro_rules! impl_rand_for_fixed_hash {
 	};
 }
 
+// Implementation for disabled libc crate support.
+//
+// # Note
+//
+// Feature guarded macro definitions instead of feature guarded impl blocks
+// to work around the problems of introducing `libc` crate feature in
+// a user crate.
+#[cfg(not(all(feature = "libc", not(target_os = "unknown"))))]
 #[macro_export]
 #[doc(hidden)]
-macro_rules! impl_cmp_for_fixed_hash {
+macro_rules! impl_libc_for_fixed_hash {
 	( $name:ident ) => {
 		impl $crate::core_::cmp::PartialEq for $name {
 			#[inline]
@@ -547,6 +555,52 @@ macro_rules! impl_cmp_for_fixed_hash {
 	};
 }
 
+// Implementation for enabled libc crate support.
+//
+// # Note
+//
+// Feature guarded macro definitions instead of feature guarded impl blocks
+// to work around the problems of introducing `libc` crate feature in
+// a user crate.
+#[cfg(all(feature = "libc", not(target_os = "unknown")))]
+#[macro_export]
+#[doc(hidden)]
+macro_rules! impl_libc_for_fixed_hash {
+	( $name:ident ) => {
+		impl $crate::core_::cmp::PartialEq for $name {
+			#[inline]
+			fn eq(&self, other: &Self) -> bool {
+				unsafe {
+					$crate::libc::memcmp(
+						self.as_ptr() as *const $crate::libc::c_void,
+						other.as_ptr() as *const $crate::libc::c_void,
+						Self::len_bytes(),
+					) == 0
+				}
+			}
+		}
+
+		impl $crate::core_::cmp::Ord for $name {
+			fn cmp(&self, other: &Self) -> $crate::core_::cmp::Ordering {
+				let r = unsafe {
+					$crate::libc::memcmp(
+						self.as_ptr() as *const $crate::libc::c_void,
+						other.as_ptr() as *const $crate::libc::c_void,
+						Self::len_bytes(),
+					)
+				};
+				if r < 0 {
+					return $crate::core_::cmp::Ordering::Less;
+				}
+				if r > 0 {
+					return $crate::core_::cmp::Ordering::Greater;
+				}
+				$crate::core_::cmp::Ordering::Equal
+			}
+		}
+	};
+}
+
 // Implementation for disabled rustc-hex crate support.
 //
 // # Note

fixed-hash/src/lib.rs

@@ -18,6 +18,10 @@ pub extern crate alloc as alloc_;
 #[doc(hidden)]
 pub use core as core_;
 
+#[cfg(all(feature = "libc", not(target_os = "unknown")))]
+#[doc(hidden)]
+pub use libc;
+
 // This disables a warning for unused #[macro_use(..)]
 // which is incorrect since the compiler does not check
 // for all available configurations.
@@ -34,6 +38,10 @@ pub use static_assertions::const_assert;
 #[doc(hidden)]
 pub use byteorder;
 
+#[cfg(not(feature = "libc"))]
+#[doc(hidden)]
+pub mod libc {}
+
 #[cfg(feature = "rustc-hex")]
 #[doc(hidden)]
 pub use rustc_hex;

primitive-types/CHANGELOG.md

@@ -5,7 +5,6 @@ The format is based on [Keep a Changelog].
 [Keep a Changelog]: http://keepachangelog.com/en/1.0.0/
 
 ## [Unreleased]
-- Removed `libc` feature. [#317](https://github.com/paritytech/parity-common/pull/317)
 
 ## [0.6.2] - 2019-01-03
 - Expose to_hex and from_hex from impl-serde. [#302](https://github.com/paritytech/parity-common/pull/302)

primitive-types/Cargo.toml

@@ -18,6 +18,7 @@ impl-rlp = { version = "0.2", path = "impls/rlp", default-features = false, opti
 default = ["std"]
 std = ["uint/std", "fixed-hash/std", "impl-codec/std"]
 byteorder = ["fixed-hash/byteorder"]
+libc = ["fixed-hash/libc"]
 rustc-hex = ["fixed-hash/rustc-hex"]
 serde = ["std", "impl-serde"]
 codec = ["impl-codec"]