Correct the third argument to ioctl on appropriate platforms.

While usually `ioctl()` passes a pointer, the function call has been
overloaded to allow integers to be passed. For some platforms this
is an `int` and on others it's a `ulong`.

Fixes #824.

CHANGELOG.md

@@ -41,6 +41,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
   ([#837](https://github.com/nix-rust/nix/pull/837))
 - Fixed `ioctl_write_int!` on FreeBSD/DragonFlyBSD
   ([#833](https://github.com/nix-rust/nix/pull/833))
+- `ioctl_write_int!` now properly supports passing a `c_ulong` as the parameter on Linux non-musl targets
+  ([#833](https://github.com/nix-rust/nix/pull/833))
 
 ### Removed
 - Removed explicit support for the `bytes` crate from the `sys::aio` module.

src/sys/ioctl/bsd.rs

@@ -1,6 +1,9 @@
 /// The datatype used for the ioctl number
 #[doc(hidden)]
 pub type ioctl_num_type = ::libc::c_ulong;
+/// The datatype used for the 3rd argument
+#[doc(hidden)]
+pub type ioctl_param_type = ::libc::c_int;
 
 mod consts {
     use ::sys::ioctl::ioctl_num_type;

src/sys/ioctl/linux.rs

@@ -5,6 +5,9 @@ pub type ioctl_num_type = ::libc::c_int;
 #[cfg(not(any(target_os = "android", target_env = "musl")))]
 #[doc(hidden)]
 pub type ioctl_num_type = ::libc::c_ulong;
+/// The datatype used for the 3rd argument
+#[doc(hidden)]
+pub type ioctl_param_type = ::libc::c_ulong;
 
 #[doc(hidden)]
 pub const NRBITS: ioctl_num_type = 8;

src/sys/ioctl/mod.rs

@@ -519,7 +519,7 @@ cfg_if!{
             ($(#[$attr:meta])* $name:ident, $ioty:expr, $nr:expr) => (
                 $(#[$attr])*
                 pub unsafe fn $name(fd: $crate::libc::c_int,
-                                    data: $crate::libc::c_int)
+                                    data: $crate::sys::ioctl::ioctl_param_type)
                                     -> $crate::Result<$crate::libc::c_int> {
                     convert_ioctl_res!($crate::libc::ioctl(fd, request_code_write_int!($ioty, $nr) as $crate::sys::ioctl::ioctl_num_type, data))
                 }
@@ -556,7 +556,7 @@ cfg_if!{
             ($(#[$attr:meta])* $name:ident, $ioty:expr, $nr:expr) => (
                 $(#[$attr])*
                 pub unsafe fn $name(fd: $crate::libc::c_int,
-                                    data: $crate::libc::c_int)
+                                    data: $crate::sys::ioctl::ioctl_param_type)
                                     -> $crate::Result<$crate::libc::c_int> {
                     convert_ioctl_res!($crate::libc::ioctl(fd, request_code_write!($ioty, $nr, ::std::mem::size_of::<$crate::libc::c_int>()) as $crate::sys::ioctl::ioctl_num_type, data))
                 }