Auto merge of #392 - fiveop:less_ffi, r=@fiveop

Replace ffi module by libc functions in mqueue.rs

This is almost finished. I still need to check if I introduced any breaking changes by changing signatures. I would want to record this in the change log, however, for that we still need to merge #391.

- [x] update change log
- [x] run rustfmt on `src/mqueue.rs`

Author: homu

CHANGELOG.md

@@ -40,6 +40,18 @@ This project adheres to [Semantic Versioning](http://semver.org/).
   `::nix::sched` to `Result<bool>` and `Result<()>`, respectively. They now
   return `EINVAL`, if an invalid argument for the `field` parameter is passed.
   ([#402](https://github.com/nix-rust/nix/pull/402))
+- `MqAttr` in `::nix::mqueue` is now an opaque proxy for `::libc::mq_attr`,
+  which has the same structure as the old `MqAttr`. The field `mq_flags` of
+  `::libc::mq_attr` is readable using the new method `flags()` of `MqAttr`.
+  `MqAttr` also no longer implements `Debug`.
+  ([#0](https://github.com/nix-rust/nix/pull/0))
+- The parameter `msq_prio` of `mq_receive` with type `u32` in `::nix::mqueue`
+  was replaced by a parameter named `msg_prio` with type `&mut u32`, so that
+  the message priority can be obtained by the caller.
+  ([#0](https://github.com/nix-rust/nix/pull/0))
+- The type alias `MQd` in `::nix::queue` was replaced by the type alias
+  `libc::mqd_t`, both of which are aliases for the same type.
+  ([#0](https://github.com/nix-rust/nix/pull/0))
 
 ### Removed
 - Type alias `SigNum` from `::nix::sys::signal`.

src/lib.rs

@@ -40,7 +40,7 @@ pub mod fcntl;
 #[cfg(any(target_os = "linux", target_os = "android"))]
 pub mod mount;
 
-#[cfg(any(target_os = "linux"))]
+#[cfg(target_os = "linux")]
 pub mod mqueue;
 
 #[cfg(any(target_os = "linux", target_os = "macos"))]

src/mqueue.rs

@@ -4,142 +4,150 @@
 
 use {Errno, Result};
 
-use libc::{c_int, c_long, c_char, size_t, mode_t};
+use libc::{self, c_char, c_long, mode_t, mqd_t, size_t};
 use std::ffi::CString;
 use sys::stat::Mode;
-use std::ptr;
-
-pub use self::consts::*;
-
-pub type MQd = c_int;
-
-#[cfg(target_os = "linux")]
-mod consts {
-    use libc::c_int;
-
-    bitflags!(
-        flags MQ_OFlag: c_int {
-            const O_RDONLY    = 0o00000000,
-            const O_WRONLY    = 0o00000001,
-            const O_RDWR      = 0o00000002,
-            const O_CREAT     = 0o00000100,
-            const O_EXCL      = 0o00000200,
-            const O_NONBLOCK  = 0o00004000,
-            const O_CLOEXEC   = 0o02000000,
-        }
-    );
-
-    bitflags!(
-        flags FdFlag: c_int {
-            const FD_CLOEXEC = 1
-        }
-    );
+use std::mem;
+
+libc_bitflags!{
+    flags MQ_OFlag: libc::c_int {
+        O_RDONLY,
+        O_WRONLY,
+        O_RDWR,
+        O_CREAT,
+        O_EXCL,
+        O_NONBLOCK,
+        O_CLOEXEC,
+    }
 }
 
-mod ffi {
-    use libc::{c_char, size_t, ssize_t, c_uint, c_int};
-    use super::MQd;
-    use super::MqAttr;
-
-    #[allow(improper_ctypes)]
-    extern "C" {
-        pub fn mq_open(name: *const c_char, oflag: c_int, ...) -> MQd;
-
-        pub fn mq_close (mqd: MQd) -> c_int;
-
-        pub fn mq_unlink(name: *const c_char) -> c_int;
-
-        pub fn mq_receive (mqd: MQd, msg_ptr: *const c_char, msg_len: size_t, msq_prio: *const c_uint) -> ssize_t;
-
-        pub fn mq_send (mqd: MQd, msg_ptr: *const c_char, msg_len: size_t, msq_prio: c_uint) -> c_int;
-
-        pub fn mq_getattr(mqd: MQd, attr: *mut MqAttr) -> c_int;
-
-        pub fn mq_setattr(mqd: MQd, newattr: *const MqAttr, oldattr: *mut MqAttr) -> c_int;
+libc_bitflags!{
+    flags FdFlag: libc::c_int {
+        FD_CLOEXEC,
     }
 }
 
 #[repr(C)]
-#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[derive(Clone, Copy)]
 pub struct MqAttr {
-    pub mq_flags: c_long,
-    pub mq_maxmsg: c_long,
-    pub mq_msgsize: c_long,
-    pub mq_curmsgs: c_long,
-    pad: [c_long; 4]
+    mq_attr: libc::mq_attr,
 }
 
-impl MqAttr {
-   pub fn new(mq_flags: c_long, mq_maxmsg: c_long, mq_msgsize: c_long, mq_curmsgs: c_long) -> MqAttr {
-       MqAttr { mq_flags: mq_flags, mq_maxmsg: mq_maxmsg, mq_msgsize: mq_msgsize, mq_curmsgs: mq_curmsgs, pad: [0; 4] }
-   }
+impl PartialEq<MqAttr> for MqAttr {
+    fn eq(&self, other: &MqAttr) -> bool {
+        let self_attr = self.mq_attr;
+        let other_attr = other.mq_attr;
+        self_attr.mq_flags == other_attr.mq_flags && self_attr.mq_maxmsg == other_attr.mq_maxmsg &&
+        self_attr.mq_msgsize == other_attr.mq_msgsize &&
+        self_attr.mq_curmsgs == other_attr.mq_curmsgs
+    }
 }
 
+impl MqAttr {
+    pub fn new(mq_flags: c_long,
+               mq_maxmsg: c_long,
+               mq_msgsize: c_long,
+               mq_curmsgs: c_long)
+               -> MqAttr {
+        let mut attr = unsafe { mem::uninitialized::<libc::mq_attr>() };
+        attr.mq_flags = mq_flags;
+        attr.mq_maxmsg = mq_maxmsg;
+        attr.mq_msgsize = mq_msgsize;
+        attr.mq_curmsgs = mq_curmsgs;
+        MqAttr { mq_attr: attr }
+    }
 
-pub fn mq_open(name: &CString, oflag: MQ_OFlag, mode: Mode, attr: Option<&MqAttr>) -> Result<MQd> {
-    let attr_p = attr.map(|attr| attr as *const MqAttr).unwrap_or(ptr::null());
-    let res = unsafe { ffi::mq_open(name.as_ptr(), oflag.bits(), mode.bits() as mode_t, attr_p) };
+    pub fn flags(&self) -> c_long {
+        self.mq_attr.mq_flags
+    }
+}
 
+
+pub fn mq_open(name: &CString,
+               oflag: MQ_OFlag,
+               mode: Mode,
+               attr: Option<&MqAttr>)
+               -> Result<mqd_t> {
+    let res = match attr {
+        Some(mq_attr) => unsafe {
+            libc::mq_open(name.as_ptr(),
+                          oflag.bits(),
+                          mode.bits() as mode_t,
+                          &mq_attr.mq_attr as *const libc::mq_attr)
+        },
+        None => unsafe { libc::mq_open(name.as_ptr(), oflag.bits()) },
+    };
     Errno::result(res)
 }
 
 pub fn mq_unlink(name: &CString) -> Result<()> {
-    let res = unsafe { ffi::mq_unlink(name.as_ptr()) };
+    let res = unsafe { libc::mq_unlink(name.as_ptr()) };
     Errno::result(res).map(drop)
 }
 
-pub fn mq_close(mqdes: MQd) -> Result<()>  {
-    let res = unsafe { ffi::mq_close(mqdes) };
+pub fn mq_close(mqdes: mqd_t) -> Result<()> {
+    let res = unsafe { libc::mq_close(mqdes) };
     Errno::result(res).map(drop)
 }
 
-
-pub fn mq_receive(mqdes: MQd, message: &mut [u8], msq_prio: u32) -> Result<usize> {
+pub fn mq_receive(mqdes: mqd_t, message: &mut [u8], msg_prio: &mut u32) -> Result<usize> {
     let len = message.len() as size_t;
-    let res = unsafe { ffi::mq_receive(mqdes, message.as_mut_ptr() as *mut c_char, len, &msq_prio) };
-
+    let res = unsafe {
+        libc::mq_receive(mqdes,
+                         message.as_mut_ptr() as *mut c_char,
+                         len,
+                         msg_prio as *mut u32)
+    };
     Errno::result(res).map(|r| r as usize)
 }
 
-pub fn mq_send(mqdes: MQd, message: &[u8], msq_prio: u32) -> Result<()> {
-    let res = unsafe { ffi::mq_send(mqdes, message.as_ptr() as *const c_char, message.len(), msq_prio) };
-
+pub fn mq_send(mqdes: mqd_t, message: &[u8], msq_prio: u32) -> Result<()> {
+    let res = unsafe {
+        libc::mq_send(mqdes,
+                      message.as_ptr() as *const c_char,
+                      message.len(),
+                      msq_prio)
+    };
     Errno::result(res).map(drop)
 }
 
-pub fn mq_getattr(mqd: MQd) -> Result<MqAttr> {
-    let mut attr = MqAttr::new(0, 0, 0, 0);
-    let res = unsafe { ffi::mq_getattr(mqd, &mut attr) };
-    try!(Errno::result(res));
-    Ok(attr)
+pub fn mq_getattr(mqd: mqd_t) -> Result<MqAttr> {
+    let mut attr = unsafe { mem::uninitialized::<libc::mq_attr>() };
+    let res = unsafe { libc::mq_getattr(mqd, &mut attr) };
+    Errno::result(res).map(|_| MqAttr { mq_attr: attr })
 }
 
 /// Set the attributes of the message queue. Only `O_NONBLOCK` can be set, everything else will be ignored
 /// Returns the old attributes
 /// It is recommend to use the `mq_set_nonblock()` and `mq_remove_nonblock()` convenience functions as they are easier to use
 ///
 /// [Further reading](http://man7.org/linux/man-pages/man3/mq_setattr.3.html)
-pub fn mq_setattr(mqd: MQd, newattr: &MqAttr) -> Result<MqAttr> {
-    let mut attr = MqAttr::new(0, 0, 0, 0);
-    let res = unsafe { ffi::mq_setattr(mqd, newattr as *const MqAttr, &mut attr) };
-    try!(Errno::result(res));
-    Ok(attr)
+pub fn mq_setattr(mqd: mqd_t, newattr: &MqAttr) -> Result<MqAttr> {
+    let mut attr = unsafe { mem::uninitialized::<libc::mq_attr>() };
+    let res = unsafe { libc::mq_setattr(mqd, &newattr.mq_attr as *const libc::mq_attr, &mut attr) };
+    Errno::result(res).map(|_| MqAttr { mq_attr: attr })
 }
 
 /// Convenience function.
 /// Sets the `O_NONBLOCK` attribute for a given message queue descriptor
 /// Returns the old attributes
-pub fn mq_set_nonblock(mqd: MQd) -> Result<(MqAttr)> {
+pub fn mq_set_nonblock(mqd: mqd_t) -> Result<(MqAttr)> {
     let oldattr = try!(mq_getattr(mqd));
-    let newattr = MqAttr::new(O_NONBLOCK.bits() as c_long, oldattr.mq_maxmsg, oldattr.mq_msgsize, oldattr.mq_curmsgs);
+    let newattr = MqAttr::new(O_NONBLOCK.bits() as c_long,
+                              oldattr.mq_attr.mq_maxmsg,
+                              oldattr.mq_attr.mq_msgsize,
+                              oldattr.mq_attr.mq_curmsgs);
     mq_setattr(mqd, &newattr)
 }
 
 /// Convenience function.
 /// Removes `O_NONBLOCK` attribute for a given message queue descriptor
 /// Returns the old attributes
-pub fn mq_remove_nonblock(mqd: MQd) -> Result<(MqAttr)> {
+pub fn mq_remove_nonblock(mqd: mqd_t) -> Result<(MqAttr)> {
     let oldattr = try!(mq_getattr(mqd));
-    let newattr = MqAttr::new(0, oldattr.mq_maxmsg, oldattr.mq_msgsize, oldattr.mq_curmsgs);
+    let newattr = MqAttr::new(0,
+                              oldattr.mq_attr.mq_maxmsg,
+                              oldattr.mq_attr.mq_msgsize,
+                              oldattr.mq_attr.mq_curmsgs);
     mq_setattr(mqd, &newattr)
 }

test/test_mq.rs

@@ -33,7 +33,9 @@ fn test_mq_send_and_receive() {
             let mq_name_in_child =  &CString::new(b"/a_nix_test_queue".as_ref()).unwrap();
             let mqd_in_child = mq_open(mq_name_in_child, O_CREAT | O_RDONLY, S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH, Some(&attr)).unwrap();
             let mut buf = [0u8; 32];
-            mq_receive(mqd_in_child, &mut buf, 1).unwrap();
+            let mut prio = 0u32;
+            mq_receive(mqd_in_child, &mut buf, &mut prio).unwrap();
+            assert!(prio == 1);
             write(writer, &buf).unwrap();  // pipe result to parent process. Otherwise cargo does not report test failures correctly
             mq_close(mqd_in_child).unwrap();
       }
@@ -99,10 +101,10 @@ fn test_mq_set_nonblocking() {
     let mqd = mq_open(mq_name, O_CREAT | O_WRONLY, S_IWUSR | S_IRUSR | S_IRGRP | S_IROTH, Some(&initial_attr)).unwrap();
     mq_set_nonblock(mqd).unwrap();
     let new_attr = mq_getattr(mqd);
-    assert!(new_attr.unwrap().mq_flags == O_NONBLOCK.bits() as c_long);
+    assert!(new_attr.unwrap().flags() == O_NONBLOCK.bits() as c_long);
     mq_remove_nonblock(mqd).unwrap();
     let new_attr = mq_getattr(mqd);
-    assert!(new_attr.unwrap().mq_flags == 0);
+    assert!(new_attr.unwrap().flags() == 0);
     mq_close(mqd).unwrap();
 }