Cast pointers more carefully

src/fcntl.rs

@@ -1,5 +1,5 @@
 use crate::errno::Errno;
-use libc::{self, c_char, c_int, c_uint, size_t, ssize_t};
+use libc::{self, c_int, c_uint, size_t, ssize_t};
 use std::ffi::OsString;
 #[cfg(not(target_os = "redox"))]
 use std::os::raw;
@@ -306,12 +306,12 @@ fn readlink_maybe_at<P: ?Sized + NixPath>(
             Some(dirfd) => libc::readlinkat(
                 dirfd,
                 cstr.as_ptr(),
-                v.as_mut_ptr() as *mut c_char,
+                v.as_mut_ptr().cast(),
                 v.capacity() as size_t,
             ),
             None => libc::readlink(
                 cstr.as_ptr(),
-                v.as_mut_ptr() as *mut c_char,
+                v.as_mut_ptr().cast(),
                 v.capacity() as size_t,
             ),
         }
@@ -724,7 +724,7 @@ pub fn vmsplice(
     let ret = unsafe {
         libc::vmsplice(
             fd,
-            iov.as_ptr() as *const libc::iovec,
+            iov.as_ptr().cast(),
             iov.len(),
             flags.bits(),
         )

src/ifaddrs.rs

@@ -65,7 +65,7 @@ unsafe fn workaround_xnu_bug(info: &libc::ifaddrs) -> Option<SockaddrStorage> {
     // memcpy only sa_len bytes, assume the rest is zero
     std::ptr::copy_nonoverlapping(
         src_sock as *const u8,
-        dst_sock.as_mut_ptr() as *mut u8,
+        dst_sock.as_mut_ptr().cast(),
         (*src_sock).sa_len.into(),
     );
 

src/lib.rs

@@ -311,7 +311,7 @@ impl NixPath for [u8] {
         }
 
         let mut buf = MaybeUninit::<[u8; MAX_STACK_ALLOCATION]>::uninit();
-        let buf_ptr = buf.as_mut_ptr() as *mut u8;
+        let buf_ptr = buf.as_mut_ptr().cast();
 
         unsafe {
             ptr::copy_nonoverlapping(self.as_ptr(), buf_ptr, self.len());

src/mount/bsd.rs

@@ -215,7 +215,7 @@ impl<'a> Nmount<'a> {
     /// Helper function to push a slice onto the `iov` array.
     fn push_slice(&mut self, val: &'a [u8], is_owned: bool) {
         self.iov.push(libc::iovec {
-            iov_base: val.as_ptr() as *mut _,
+            iov_base: val.as_ptr().cast_mut().cast(),
             iov_len: val.len(),
         });
         self.is_owned.push(is_owned);
@@ -386,7 +386,7 @@ impl<'a> Nmount<'a> {
         // SAFETY: we are pushing a mutable iovec here, so we can't use
         //         the above method
         self.iov.push(libc::iovec {
-            iov_base: errmsg.as_mut_ptr() as *mut c_void,
+            iov_base: errmsg.as_mut_ptr().cast(),
             iov_len: errmsg.len(),
         });
 

src/mqueue.rs

@@ -35,7 +35,7 @@ use crate::NixPath;
 use crate::Result;
 
 use crate::sys::stat::Mode;
-use libc::{self, c_char, mqd_t, size_t};
+use libc::{self, mqd_t, size_t};
 use std::mem;
 #[cfg(any(
     target_os = "linux",
@@ -205,7 +205,7 @@ pub fn mq_receive(
     let res = unsafe {
         libc::mq_receive(
             mqdes.0,
-            message.as_mut_ptr() as *mut c_char,
+            message.as_mut_ptr().cast(),
             len,
             msg_prio as *mut u32,
         )
@@ -229,7 +229,7 @@ feature! {
         let res = unsafe {
             libc::mq_timedreceive(
                 mqdes.0,
-                message.as_mut_ptr() as *mut c_char,
+                message.as_mut_ptr().cast(),
                 len,
                 msg_prio as *mut u32,
                 abstime.as_ref(),
@@ -244,12 +244,7 @@ feature! {
 /// See also [`mq_send(2)`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/mq_send.html)
 pub fn mq_send(mqdes: &MqdT, message: &[u8], msq_prio: u32) -> Result<()> {
     let res = unsafe {
-        libc::mq_send(
-            mqdes.0,
-            message.as_ptr() as *const c_char,
-            message.len(),
-            msq_prio,
-        )
+        libc::mq_send(mqdes.0, message.as_ptr().cast(), message.len(), msq_prio)
     };
     Errno::result(res).map(drop)
 }

src/net/if_.rs

@@ -373,6 +373,7 @@ mod if_nameindex {
     }
 
     /// A list of the network interfaces available on this system. Obtained from [`if_nameindex()`].
+    #[repr(transparent)]
     pub struct Interfaces {
         ptr: NonNull<libc::if_nameindex>,
     }
@@ -388,7 +389,7 @@ mod if_nameindex {
         /// null-terminated, so calling this calculates the length. If random access isn't needed,
         /// [`Interfaces::iter()`] should be used instead.
         pub fn to_slice(&self) -> &[Interface] {
-            let ifs = self.ptr.as_ptr() as *const Interface;
+            let ifs = self.ptr.as_ptr().cast();
             let len = self.iter().count();
             unsafe { std::slice::from_raw_parts(ifs, len) }
         }

src/poll.rs

@@ -190,11 +190,7 @@ libc_bitflags! {
 /// ready.
 pub fn poll(fds: &mut [PollFd], timeout: libc::c_int) -> Result<libc::c_int> {
     let res = unsafe {
-        libc::poll(
-            fds.as_mut_ptr() as *mut libc::pollfd,
-            fds.len() as libc::nfds_t,
-            timeout,
-        )
+        libc::poll(fds.as_mut_ptr().cast(), fds.len() as libc::nfds_t, timeout)
     };
 
     Errno::result(res)
@@ -223,7 +219,7 @@ pub fn ppoll(
     let timeout = timeout.as_ref().map_or(core::ptr::null(), |r| r.as_ref());
     let sigmask = sigmask.as_ref().map_or(core::ptr::null(), |r| r.as_ref());
     let res = unsafe {
-        libc::ppoll(fds.as_mut_ptr() as *mut libc::pollfd,
+        libc::ppoll(fds.as_mut_ptr().cast(),
                     fds.len() as libc::nfds_t,
                     timeout,
                     sigmask)

src/sys/aio.rs

@@ -35,7 +35,7 @@ use std::{
     ptr, thread,
 };
 
-use libc::{c_void, off_t};
+use libc::off_t;
 use pin_utils::unsafe_pinned;
 
 use crate::{
@@ -581,7 +581,7 @@ impl<'a> AioRead<'a> {
     ) -> Self {
         let mut aiocb = AioCb::common_init(fd, prio, sigev_notify);
         aiocb.aiocb.0.aio_nbytes = buf.len();
-        aiocb.aiocb.0.aio_buf = buf.as_mut_ptr() as *mut c_void;
+        aiocb.aiocb.0.aio_buf = buf.as_mut_ptr().cast();
         aiocb.aiocb.0.aio_lio_opcode = libc::LIO_READ;
         aiocb.aiocb.0.aio_offset = offs;
         AioRead {
@@ -702,7 +702,7 @@ impl<'a> AioReadv<'a> {
         // In vectored mode, aio_nbytes stores the length of the iovec array,
         // not the byte count.
         aiocb.aiocb.0.aio_nbytes = bufs.len();
-        aiocb.aiocb.0.aio_buf = bufs.as_mut_ptr() as *mut c_void;
+        aiocb.aiocb.0.aio_buf = bufs.as_mut_ptr().cast();
         aiocb.aiocb.0.aio_lio_opcode = libc::LIO_READV;
         aiocb.aiocb.0.aio_offset = offs;
         AioReadv {
@@ -817,7 +817,7 @@ impl<'a> AioWrite<'a> {
         // but technically its only unsafe to dereference it, not to create
         // it.  Type Safety guarantees that we'll never pass aiocb to
         // aio_read or aio_readv.
-        aiocb.aiocb.0.aio_buf = buf.as_ptr() as *mut c_void;
+        aiocb.aiocb.0.aio_buf = buf.as_ptr().cast_mut().cast();
         aiocb.aiocb.0.aio_lio_opcode = libc::LIO_WRITE;
         aiocb.aiocb.0.aio_offset = offs;
         AioWrite {
@@ -935,7 +935,7 @@ impl<'a> AioWritev<'a> {
         // but technically its only unsafe to dereference it, not to create
         // it.  Type Safety guarantees that we'll never pass aiocb to
         // aio_read or aio_readv.
-        aiocb.aiocb.0.aio_buf = bufs.as_ptr() as *mut c_void;
+        aiocb.aiocb.0.aio_buf = bufs.as_ptr().cast_mut().cast();
         aiocb.aiocb.0.aio_lio_opcode = libc::LIO_WRITEV;
         aiocb.aiocb.0.aio_offset = offs;
         AioWritev {

src/sys/epoll.rs

@@ -148,7 +148,7 @@ impl Epoll {
         let res = unsafe {
             libc::epoll_wait(
                 self.0.as_raw_fd(),
-                events.as_mut_ptr() as *mut libc::epoll_event,
+                events.as_mut_ptr().cast(),
                 events.len() as c_int,
                 timeout as c_int,
             )
@@ -240,7 +240,7 @@ pub fn epoll_wait(
     let res = unsafe {
         libc::epoll_wait(
             epfd,
-            events.as_mut_ptr() as *mut libc::epoll_event,
+            events.as_mut_ptr().cast(),
             events.len() as c_int,
             timeout_ms as c_int,
         )

src/sys/event.rs

@@ -63,9 +63,9 @@ impl Kqueue {
         let res = unsafe {
             libc::kevent(
                 self.0.as_raw_fd(),
-                changelist.as_ptr() as *const libc::kevent,
+                changelist.as_ptr().cast(),
                 changelist.len() as type_of_nchanges,
-                eventlist.as_mut_ptr() as *mut libc::kevent,
+                eventlist.as_mut_ptr().cast(),
                 eventlist.len() as type_of_nchanges,
                 if let Some(ref timeout) = timeout_opt {
                     timeout as *const timespec

src/sys/inotify.rs

@@ -202,7 +202,7 @@ impl Inotify {
                 let mut event = MaybeUninit::<libc::inotify_event>::uninit();
                 ptr::copy_nonoverlapping(
                     buffer.as_ptr().add(offset),
-                    event.as_mut_ptr() as *mut u8,
+                    event.as_mut_ptr().cast(),
                     (BUFSIZ - offset).min(header_size),
                 );
                 event.assume_init()

src/sys/ptrace/linux.rs

@@ -241,13 +241,13 @@ pub fn setregs(pid: Pid, regs: user_regs_struct) -> Result<()> {
 /// and therefore use the data field to return values. This function handles these
 /// requests.
 fn ptrace_get_data<T>(request: Request, pid: Pid) -> Result<T> {
-    let mut data = mem::MaybeUninit::uninit();
+    let mut data = mem::MaybeUninit::<T>::uninit();
     let res = unsafe {
         libc::ptrace(
             request as RequestType,
             libc::pid_t::from(pid),
             ptr::null_mut::<T>(),
-            data.as_mut_ptr() as *const _ as *const c_void,
+            data.as_mut_ptr(),
         )
     };
     Errno::result(res)?;

src/sys/quota.rs

@@ -264,7 +264,7 @@ pub fn quotactl_on<P: ?Sized + NixPath>(
 ) -> Result<()> {
     quota_file.with_nix_path(|path| {
         let mut path_copy = path.to_bytes_with_nul().to_owned();
-        let p: *mut c_char = path_copy.as_mut_ptr() as *mut c_char;
+        let p: *mut c_char = path_copy.as_mut_ptr().cast();
         quotactl(
             QuotaCmd(QuotaSubCmd::Q_QUOTAON, which),
             Some(special),
@@ -308,12 +308,12 @@ pub fn quotactl_get<P: ?Sized + NixPath>(
     special: &P,
     id: c_int,
 ) -> Result<Dqblk> {
-    let mut dqblk = mem::MaybeUninit::uninit();
+    let mut dqblk = mem::MaybeUninit::<libc::dqblk>::uninit();
     quotactl(
         QuotaCmd(QuotaSubCmd::Q_GETQUOTA, which),
         Some(special),
         id,
-        dqblk.as_mut_ptr() as *mut c_char,
+        dqblk.as_mut_ptr().cast(),
     )?;
     Ok(unsafe { Dqblk(dqblk.assume_init()) })
 }

src/sys/sendfile.rs

@@ -96,22 +96,24 @@ cfg_if! {
                 headers: Option<&'a [&'a [u8]]>,
                 trailers: Option<&'a [&'a [u8]]>
             ) -> SendfileHeaderTrailer<'a> {
-                let header_iovecs: Option<Vec<IoSlice<'_>>> =
+                let mut header_iovecs: Option<Vec<IoSlice<'_>>> =
                     headers.map(|s| s.iter().map(|b| IoSlice::new(b)).collect());
-                let trailer_iovecs: Option<Vec<IoSlice<'_>>> =
+                let mut trailer_iovecs: Option<Vec<IoSlice<'_>>> =
                     trailers.map(|s| s.iter().map(|b| IoSlice::new(b)).collect());
                 SendfileHeaderTrailer(
                     libc::sf_hdtr {
                         headers: {
                             header_iovecs
-                                .as_ref()
-                                .map_or(ptr::null(), |v| v.as_ptr()) as *mut libc::iovec
+                                .as_mut()
+                                .map_or(ptr::null_mut(), |v| v.as_mut_ptr())
+                                .cast()
                         },
                         hdr_cnt: header_iovecs.as_ref().map(|v| v.len()).unwrap_or(0) as i32,
                         trailers: {
                             trailer_iovecs
-                                .as_ref()
-                                .map_or(ptr::null(), |v| v.as_ptr()) as *mut libc::iovec
+                                .as_mut()
+                                .map_or(ptr::null_mut(), |v| v.as_mut_ptr())
+                                .cast()
                         },
                         trl_cnt: trailer_iovecs.as_ref().map(|v| v.len()).unwrap_or(0) as i32
                     },

src/sys/signalfd.rs

@@ -109,7 +109,7 @@ impl SignalFd {
 
         let size = mem::size_of_val(&buffer);
         let res = Errno::result(unsafe {
-            libc::read(self.0.as_raw_fd(), buffer.as_mut_ptr() as *mut libc::c_void, size)
+            libc::read(self.0.as_raw_fd(), buffer.as_mut_ptr().cast(), size)
         })
         .map(|r| r as usize);
         match res {