Unify the ioctl declarations on linux

See the comment for why

Author: espindola

src/unix/linux_like/linux/gnu/mod.rs

@@ -5,16 +5,6 @@ pub type Lmid_t = ::c_long;
 pub type regoff_t = ::c_int;
 pub type __kernel_rwf_t = ::c_int;
 
-cfg_if! {
-    if #[cfg(doc)] {
-        // Used in `linux::arch` to define ioctl constants.
-        pub(crate) type Ioctl = ::c_ulong;
-    } else {
-        #[doc(hidden)]
-        pub type Ioctl = ::c_ulong;
-    }
-}
-
 s! {
     pub struct statx {
         pub stx_mask: u32,
@@ -1393,7 +1383,6 @@ extern "C" {
     pub fn reallocarray(ptr: *mut ::c_void, nmemb: ::size_t, size: ::size_t) -> *mut ::c_void;
 
     pub fn ctermid(s: *mut ::c_char) -> *mut ::c_char;
-    pub fn ioctl(fd: ::c_int, request: ::c_ulong, ...) -> ::c_int;
     pub fn backtrace(buf: *mut *mut ::c_void, sz: ::c_int) -> ::c_int;
     pub fn glob64(
         pattern: *const ::c_char,

src/unix/linux_like/linux/mod.rs

@@ -53,6 +53,35 @@ cfg_if! {
     }
 }
 
+// In POSIX, the request is a int, and that is what is used by
+// musl.
+//
+// In the linux kernel the request is treated as a 32 bit packed
+// value, where, in particular, the most significant bit is used
+// to indicate that this ioctl is a read operation.
+//
+// In glibc and ulibc the request is declared as an unsigned long.
+//
+// In C these differences are not super important since the value
+// is passed the same way. Rust is stricter and complains if,
+// using a c_int on musl, one tries to call
+//
+// libc::ioctl(..., 0xc0104801, ...);
+//
+// We then use a c_uint to help portability, since:
+// * Anyone using a value larger than 32 bits has a bug
+// * Using unsigned constants is more convenient
+// * The most common implementation, glibc, used an unsigned request before.
+cfg_if! {
+    if #[cfg(doc)] {
+        // Used in `linux::arch` to define ioctl constants.
+        pub(crate) type Ioctl = ::c_uint;
+    } else {
+        #[doc(hidden)]
+        pub type Ioctl = ::c_uint;
+    }
+}
+
 // linux/can.h
 pub type canid_t = u32;
 
@@ -6087,6 +6116,8 @@ extern "C" {
         len: ::size_t,
         flags: ::c_uint,
     ) -> ::ssize_t;
+
+    pub fn ioctl(fd: ::c_int, request: ::Ioctl, ...) -> ::c_int;
 }
 
 // LFS64 extensions

src/unix/linux_like/linux/musl/mod.rs

@@ -22,16 +22,6 @@ pub type fsblkcnt_t = ::c_ulonglong;
 pub type fsfilcnt_t = ::c_ulonglong;
 pub type rlim_t = ::c_ulonglong;
 
-cfg_if! {
-    if #[cfg(doc)] {
-        // Used in `linux::arch` to define ioctl constants.
-        pub(crate) type Ioctl = ::c_int;
-    } else {
-        #[doc(hidden)]
-        pub type Ioctl = ::c_int;
-    }
-}
-
 impl siginfo_t {
     pub unsafe fn si_addr(&self) -> *mut ::c_void {
         #[repr(C)]
@@ -843,7 +833,6 @@ extern "C" {
         new_limit: *const ::rlimit,
         old_limit: *mut ::rlimit,
     ) -> ::c_int;
-    pub fn ioctl(fd: ::c_int, request: ::c_int, ...) -> ::c_int;
     pub fn gettimeofday(tp: *mut ::timeval, tz: *mut ::c_void) -> ::c_int;
     pub fn ptrace(request: ::c_int, ...) -> ::c_long;
     pub fn getpriority(which: ::c_int, who: ::id_t) -> ::c_int;

src/unix/linux_like/linux/uclibc/mod.rs

@@ -6,16 +6,6 @@ pub type rlim_t = ::c_ulong;
 pub type __rlimit_resource_t = ::c_ulong;
 pub type __priority_which_t = ::c_uint;
 
-cfg_if! {
-    if #[cfg(doc)] {
-        // Used in `linux::arch` to define ioctl constants.
-        pub(crate) type Ioctl = ::c_ulong;
-    } else {
-        #[doc(hidden)]
-        pub type Ioctl = ::c_ulong;
-    }
-}
-
 s! {
     pub struct statvfs {  // Different than GNU!
         pub f_bsize: ::c_ulong,
@@ -353,7 +343,6 @@ pub const UDP_SEGMENT: ::c_int = 103;
 pub const YESEXPR: ::c_int = ((5) << 8) | (0);
 
 extern "C" {
-    pub fn ioctl(fd: ::c_int, request: ::c_ulong, ...) -> ::c_int;
     pub fn gettimeofday(tp: *mut ::timeval, tz: *mut ::timezone) -> ::c_int;
 
     pub fn pthread_rwlockattr_getkind_np(