clippy: Fix several clippy issues

In order to enable several clippy lint groups fix several findings.

CHANGELOG.md

@@ -0,0 +1,14 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a
+Changelog](https://keepachangelog.com/en/1.0.0/), and this project
+adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## [Unreleased]
+
+### Changed
+
+- Fix several clippy findings in preperation to enable several lint
+  groups.

Cargo.toml

@@ -5,6 +5,9 @@ edition = "2018"
 authors = ["finga <mqrs@onders.org>"]
 repository = "https://git.onders.org/finga/mqrs"
 license = "GPL-3.0-or-later"
+description = "A simple API for SysV IPC message queues."
+keywords = ["message_queue", "mq", "mqueue", "queue", "sysv", "ipc"]
+categories = ["os"]
 
 [dependencies]
 libc = "0.2.98"

src/lib.rs

@@ -1,6 +1,5 @@
 use libc::{
-    msgctl, msgget, msginfo, msqid_ds, IPC_CREAT, IPC_EXCL, IPC_INFO, IPC_NOWAIT, IPC_PRIVATE,
-    IPC_RMID, IPC_SET, IPC_STAT, MSG_COPY, MSG_EXCEPT, MSG_INFO, MSG_NOERROR, MSG_STAT,
+    msgctl, msgget, msqid_ds, IPC_CREAT, IPC_INFO, IPC_NOWAIT, IPC_RMID, MSG_INFO, MSG_STAT,
 };
 use nix::errno::{errno, Errno};
 use std::{marker::PhantomData, mem::MaybeUninit, ptr};
@@ -12,50 +11,15 @@ pub enum SysvMqError {
     ErrnoError(&'static str),
 }
 
-/// IPC bit flags
-#[repr(i32)]
-pub enum Flags {
-    /// Create key if key does not exist.
-    CreateKey = IPC_CREAT,
-    /// Fail if key exists.
-    Exclusive = IPC_EXCL,
-    /// Return error on wait.
-    NoWait = IPC_NOWAIT,
-    /// No error if message is too big.
-    NoError = MSG_NOERROR,
-    /// Receive any message except of specified type.
-    Except = MSG_EXCEPT,
-    /// Copy (not remove) all queue messages.
-    Copy = MSG_COPY,
-    /// Private key (Special key value).
-    Private = IPC_PRIVATE,
-}
-
-/// Commands for `msgctl()`
-#[repr(i32)]
-pub enum ControlCommands {
-    /// Remove identifier (Control command for `msgctl`, `semctl`, and `shmctl`).
-    Remove = IPC_RMID,
-    /// Set `ipc_perm` options (Control command for `msgctl`, `semctl`, and `shmctl`).
-    SetPerm = IPC_SET,
-    /// Get `ipc_perm` options (Control command for `msgctl`, `semctl`, and `shmctl`).
-    GetPerm = IPC_STAT,
-    /// See ipcs (Control command for `msgctl`, `semctl`, and `shmctl`).
-    IpcInfo = IPC_INFO,
-    /// IPCS control command.
-    Stat = MSG_STAT,
-    /// IPCS control command.
-    MsgInfo = MSG_INFO,
-}
-
+#[allow(clippy::doc_markdown)]
+/// Unlink (delete) an existing SysV IPC message queue.
+///
+/// # Errors
+///
+/// Return an `SysvMqError` when no queue with the given key can be
+/// found.
 pub fn unlink_id(id: i32) -> Result<(), SysvMqError> {
-    let res = unsafe {
-        msgctl(
-            id,
-            ControlCommands::Remove as i32,
-            ptr::null::<msqid_ds>() as *mut msqid_ds,
-        )
-    };
+    let res = unsafe { msgctl(id, IPC_RMID, ptr::null::<msqid_ds>().cast_mut()) };
 
     match res {
         -1 => Err(SysvMqError::ErrnoError(Errno::from_i32(errno()).desc())),
@@ -63,6 +27,14 @@ pub fn unlink_id(id: i32) -> Result<(), SysvMqError> {
     }
 }
 
+#[allow(clippy::doc_markdown)]
+/// Get the id of an existing SysV IPC message queue by passing its
+/// key.
+///
+/// # Errors
+///
+/// Return an `SysvMqError` when no queue with the given key can be
+/// found.
 pub fn id_from_key(key: i32) -> Result<i32, SysvMqError> {
     let id = unsafe { msgget(key, 0) };
 
@@ -72,54 +44,43 @@ pub fn id_from_key(key: i32) -> Result<i32, SysvMqError> {
     }
 }
 
-pub fn ipc_info(id: i32) -> Result<(), SysvMqError> {
-    let mut msginfo = MaybeUninit::<msginfo>::uninit();
+#[allow(clippy::doc_markdown)]
+/// Get the info about an existing SysV IPC message queue.
+pub fn ipc_info(id: i32) {
+    let mut ipc_info = MaybeUninit::<msqid_ds>::uninit();
 
-    unsafe {
-        msgctl(
-            id,
-            ControlCommands::IpcInfo as i32,
-            msginfo.as_mut_ptr() as *mut msqid_ds,
-        );
+    let ipc_info = unsafe {
+        msgctl(id, IPC_INFO, ipc_info.as_mut_ptr());
+        ipc_info.assume_init()
+    };
+
+    println!("info: {ipc_info:?}");
 }
 
-    let msginfo = unsafe { msginfo.assume_init() };
+#[allow(clippy::doc_markdown)]
+/// Get the stats about an existing SysV IPC message queue.
+pub fn stat_info(id: i32) {
+    let mut stat_info = MaybeUninit::<msqid_ds>::uninit();
 
-    println!("info: {:?}", msginfo);
+    let stat_info = unsafe {
+        msgctl(id, MSG_STAT, stat_info.as_mut_ptr());
+        stat_info.assume_init()
+    };
 
-    Ok(())
+    println!("info: {stat_info:?}");
 }
 
-pub fn stat_info(id: i32) -> Result<(), SysvMqError> {
-    let mut msginfo = MaybeUninit::<msqid_ds>::uninit();
+#[allow(clippy::doc_markdown)]
+/// Get the message info about an existing SysV IPC message queue.
+pub fn msg_info(id: i32) {
+    let mut msg_info = MaybeUninit::<msqid_ds>::uninit();
 
-    unsafe {
-        msgctl(id, ControlCommands::Stat as i32, msginfo.as_mut_ptr());
-    }
+    let msg_info = unsafe {
+        msgctl(id, MSG_INFO, msg_info.as_mut_ptr());
+        msg_info.assume_init()
+    };
 
-    let msginfo = unsafe { msginfo.assume_init() };
-
-    println!("info: {:?}", msginfo);
-
-    Ok(())
-}
-
-pub fn msg_info(id: i32) -> Result<(), SysvMqError> {
-    let mut msginfo = MaybeUninit::<msginfo>::uninit();
-
-    unsafe {
-        msgctl(
-            id,
-            ControlCommands::MsgInfo as i32,
-            msginfo.as_mut_ptr() as *mut msqid_ds,
-        );
-    }
-
-    let msginfo = unsafe { msginfo.assume_init() };
-
-    println!("info: {:?}", msginfo);
-
-    Ok(())
+    println!("info: {msg_info:?}");
 }
 
 pub struct SysvMq<T> {
@@ -131,9 +92,15 @@ pub struct SysvMq<T> {
 }
 
 impl<T> SysvMq<T> {
+    /// Create a new message queye with the given key.
+    ///
+    /// # Errors
+    ///
+    /// Return an `SysvMqError` when no queue with the given key can be
+    /// created.
     pub fn create(&mut self, key: i32) -> Result<&Self, SysvMqError> {
         self.key = key;
-        self.id = unsafe { msgget(self.key, Flags::CreateKey as i32 | self.mode) };
+        self.id = unsafe { msgget(self.key, IPC_CREAT | self.mode) };
 
         match self.id {
             -1 => Err(SysvMqError::ErrnoError(Errno::from_i32(errno()).desc())),
@@ -141,6 +108,12 @@ impl<T> SysvMq<T> {
         }
     }
 
+    /// Open an existing message queye with the given key.
+    ///
+    /// # Errors
+    ///
+    /// Return an `SysvMqError` when no queue with the given key can be
+    /// found.
     pub fn open(mut self, key: i32) -> Result<Self, SysvMqError> {
         self.key = key;
         self.id = unsafe { msgget(self.key, self.mode) };
@@ -157,12 +130,13 @@ impl<T> SysvMq<T> {
     }
 
     pub fn nonblocking(&mut self) -> &Self {
-        self.message_mask |= Flags::NoWait as i32;
+        self.message_mask |= IPC_NOWAIT;
         self
     }
 
-    pub fn new() -> Self {
-        SysvMq {
+    #[must_use]
+    pub const fn new() -> Self {
+        Self {
             id: -1,
             key: 0,
             message_mask: 0,