Generic GetCString

Author: Fensteer

src/sys/socket/sockopt.rs

@@ -154,8 +154,8 @@ macro_rules! sockopt_impl {
         sockopt_impl!(Both, $name, $level, $flag, usize, GetUsize, SetUsize);
     };
 
-    (Both, $name:ident, $level:path, $flag:path, CString) => {
-        sockopt_impl!(Both, $name, $level, $flag, CString, GetCString, SetCString);
+    (Both, $name:ident, $level:path, $flag:path, CString<$ty:ty>) => {
+        sockopt_impl!(Both, $name, $level, $flag, CString, GetCString<$ty>, SetCString);
     };
 
     /*
@@ -264,7 +264,8 @@ sockopt_impl!(Both, Mark, libc::SOL_SOCKET, libc::SO_MARK, u32);
 #[cfg(any(target_os = "android", target_os = "linux"))]
 sockopt_impl!(Both, PassCred, libc::SOL_SOCKET, libc::SO_PASSCRED, bool);
 #[cfg(any(target_os = "freebsd", target_os = "linux"))] 
-sockopt_impl!(Both, TcpCongestion, libc::IPPROTO_TCP, libc::TCP_CONGESTION, CString);
+sockopt_impl!(Both, TcpCongestion, libc::IPPROTO_TCP, libc::TCP_CONGESTION, CString<[u8; 16]>);
+// TODO: Use libc::TCP_CA_NAME_MAX (https://github.com/rust-lang/libc/pull/1151)
 
 /*
  *
@@ -486,26 +487,22 @@ unsafe impl<'a> Set<'a, usize> for SetUsize {
     }
 }
 
-/// Size of empty CString buffer
-/// There is no default size in kernel documentation
-const SIZE_CSTRING_MAX : usize = 64;
-
 /// Getter for a `CString` value.
-struct GetCString {
+struct GetCString<T> {
     len: socklen_t,
-    val: [u8; SIZE_CSTRING_MAX],
+    val: T,
 }
 
-unsafe impl Get<CString> for GetCString {
+unsafe impl<T> Get<CString> for GetCString<T> {
     unsafe fn blank() -> Self {
         GetCString {
-            len: SIZE_CSTRING_MAX as socklen_t,
-            val: [0u8; SIZE_CSTRING_MAX],
+            len: mem::size_of::<T>() as socklen_t,
+            val: mem::zeroed(),
         }
     }
 
     fn ffi_ptr(&mut self) -> *mut c_void {
-        self.val.as_mut_ptr() as *mut c_void
+        &mut self.val as *mut T as *mut c_void
     }
 
     fn ffi_len(&mut self) -> *mut socklen_t {