Merge pull request #58 from andrewdavidmackenzie/rusage_under_feature_flag

Put module `pid_rusage` under a feature flag. Add flags to Cargo and describe in README.md

Author: andrewdavidmackenzie

Cargo.toml

@@ -13,6 +13,11 @@ edition = "2018"
 errno = "0.2.5"
 libc = "^0.2.62"
 
+[features]
+default = ["macosx_10_9"]
+macosx_10_7 = []
+macosx_10_9 = ["macosx_10_7"]
+
 [lib]
 name = "libproc"
 path = "src/lib.rs"

README.md

@@ -63,6 +63,7 @@ pub fn pidfdinfo<T: PIDFDInfo>(pid : i32, fd: i32) -> Result<T, String> (macos)
 ```
 
 ## PID Resource Usage related
+(Added in Mac OS X 10.9 - under "macosx_10_9" feature)
 ```
 pub fn pidrusage<T: PIDRUsage>(pid : i32) -> Result<T, String> (macos)
 ```
@@ -80,6 +81,25 @@ pub fn kmsgbuf() -> Result<String, String>
 # Platforms
 Mac OS X (10.5 and above) and Linux.
 
+## Mac OS X Versions
+Calls were aded to libproc in Mac OS X 10.7 and again in 10.9. 
+This library can be compiled to not include those calls by using rust `features`
+to enable/disable support for those versions.
+
+The default build is for Mac OS 10.9 or later. See: 
+```toml
+[features]
+default = ["macosx_10_9"]
+macosx_10_7 = []
+macosx_10_9 = ["macosx_10_7"]
+```
+in Cargo.toml
+
+To build for versions prior to Mac OS 10.7 disable the default features by passing --no-default-features to cargo.
+
+To build for Mac OS X 10.7 (or 10.8) you can enable that feature alone using
+--no-default-features --features "macosx_10_7"
+
 # Build and Test
 `cargo test` should build and test as usual for rust projects.
 

src/libproc/mod.rs

@@ -19,7 +19,8 @@ pub mod task_info;
 /// BSD specific information - very MacOS specific
 pub mod bsd_info;
 #[cfg(target_os = "macos")]
-/// Information about Process Resource Usage
+#[cfg(feature = "macosx_10_9")]
+/// Information about Process Resource Usage - added in Mac OS X 10.9
 pub mod pid_rusage;
 /// Information about Files and File Descriptors used by processes
 #[cfg(target_os = "macos")]

src/libproc/pid_rusage.rs

@@ -46,6 +46,7 @@ extern {
 /// }
 /// ```
 #[cfg(target_os = "macos")]
+#[cfg(feature = "macosx_10_9")]
 pub fn pidrusage<T: PIDRUsage>(pid : i32) -> Result<T, String> {
     let flavor = T::flavor() as i32;
     let mut pidrusage = T::default();