Fix support for DragonFly

* DragonFly does not have a O_DSYNC flag
* Fix type_of_cmsg_data on DragonFly
* No fexecve() on DragonFly
* Do not run aio test cases on DragonFly
* Keep target lists in alphabetical order
* Unscrable #[cfg] directives and use cfg_if! macro instead
* Fix errno on DragonFly

Below follows an explanation why we have to use a C extension
to get errno working on DragonFly:

DragonFly uses a thread-local errno variable, but #[thread_local] is
feature-gated and not available in stable Rust as of this writing (Rust
1.21.0). We have to use a C extension (src/errno_dragonfly.c) to access
it.

Tracking issue for `thread_local` stabilization:

    https://github.com/rust-lang/rust/issues/29594

Once this becomes stable, we can remove build.rs, src/errno_dragonfly.c,
remove the build-dependency from Cargo.toml, and use:

    extern {
        #[thread_local]
        static errno: c_int;
    }

Now all targets will use the build.rs script, but only on DragonFly this
will do something. Also, there are no additional dependencies for
targets other than DragonFly (no gcc dep).

1 files changed, 24 insertions, 24 deletions

diff --git a/src/sys/socket/ffi.rs b/src/sys/socket/ffi.rs
index 265a97c9..d91b130e 100644
--- a/src/sys/socket/ffi.rs
+++ b/src/sys/socket/ffi.rs
@@ -5,32 +5,32 @@ pub use libc::{socket, listen, bind, accept, connect, setsockopt, sendto, recvfr
 
 use libc::{c_int, c_void, socklen_t, ssize_t};
 
-#[cfg(not(target_os = "macos"))]
-use libc::size_t;
-
-#[cfg(not(target_os = "linux"))]
-use libc::c_uint;
-
 use sys::uio::IoVec;
 
-#[cfg(target_os = "linux")]
-pub type type_of_cmsg_len = size_t;
-
-#[cfg(not(target_os = "linux"))]
-pub type type_of_cmsg_len = socklen_t;
-
-// OSX always aligns struct cmsghdr as if it were a 32-bit OS
-#[cfg(target_os = "macos")]
-pub type type_of_cmsg_data = c_uint;
-
-#[cfg(not(target_os = "macos"))]
-pub type type_of_cmsg_data = size_t;
-
-#[cfg(target_os = "linux")]
-pub type type_of_msg_iovlen = size_t;
-
-#[cfg(not(target_os = "linux"))]
-pub type type_of_msg_iovlen = c_uint;
+cfg_if! {
+    if #[cfg(target_os = "dragonfly")] {
+        use libc::c_uint;
+        pub type type_of_cmsg_len = socklen_t;
+        pub type type_of_cmsg_data = c_int;
+        pub type type_of_msg_iovlen = c_uint;
+    } else if #[cfg(target_os = "linux")] {
+        use libc::size_t;
+        pub type type_of_cmsg_len = size_t;
+        pub type type_of_cmsg_data = size_t;
+        pub type type_of_msg_iovlen = size_t;
+    } else if #[cfg(target_os = "macos")] {
+        use libc::c_uint;
+        pub type type_of_cmsg_len = socklen_t;
+        // OSX always aligns struct cmsghdr as if it were a 32-bit OS
+        pub type type_of_cmsg_data = c_uint;
+        pub type type_of_msg_iovlen = c_uint;
+    } else {
+        use libc::{c_uint, size_t};
+        pub type type_of_cmsg_len = socklen_t;
+        pub type type_of_cmsg_data = size_t;
+        pub type type_of_msg_iovlen = c_uint;
+    }
+}
 
 // Private because we don't expose any external functions that operate
 // directly on this type; we just use it internally at FFI boundaries.