Enable the ptr-as-ptr and as-ptr-cast-mut Clippy lints

Replace `as *const _` / `as *mut _` pointer casts with the more
type-safe `.cast()`, `.cast::<T>()`, and `.cast_mut()` methods
throughout the codebase. Where applicable, also use `&raw const` /
`&raw mut` instead of taking a reference and casting it.

Enable the `ptr-as-ptr` and `as-ptr-cast-mut` Clippy lints as warnings
to prevent regressions.

Signed-off-by: Daniel Müller <deso@posteo.net>

Author: d-e-s-o

Cargo.toml

@@ -47,11 +47,13 @@ let-unit-value = "allow"
 module-inception = "allow"
 type-complexity = "allow"
 absolute-paths = "warn"
+as-ptr-cast-mut = "warn"
 clone-on-ref-ptr = "warn"
 dbg-macro = "warn"
 doc-markdown = "warn"
 join-absolute-paths = "warn"
 large-enum-variant = "warn"
+ptr-as-ptr = "warn"
 redundant-closure-for-method-calls = "warn"
 unchecked-time-subtraction = "warn"
 uninlined-format-args = "warn"

examples/tcp_option/src/main.rs

@@ -15,7 +15,6 @@ use libc::SOCK_NONBLOCK;
 use libc::SOCK_RAW;
 
 use libc::c_int;
-use libc::c_void;
 use libc::socklen_t;
 use std::mem::size_of_val;
 
@@ -120,7 +119,7 @@ fn main() -> Result<()> {
             target_socket_fd,
             SOL_SOCKET,
             SO_ATTACH_BPF,
-            &prog_fd as *const _ as *const c_void,
+            (&raw const prog_fd).cast(),
             size_of_val(&prog_fd) as socklen_t,
         )
     } {

libbpf-cargo/src/gen/mod.rs

@@ -755,7 +755,7 @@ fn open_bpf_object(name: &str, data: &[u8]) -> Result<Object> {
     };
     let object = unsafe {
         libbpf_sys::bpf_object__open_mem(
-            data.as_ptr() as *const c_void,
+            data.as_ptr().cast::<c_void>(),
             data.len() as c_ulong,
             &obj_opts,
         )

libbpf-rs/src/btf/mod.rs

@@ -261,7 +261,7 @@ impl<'btf> Btf<'btf> {
 
         let ptr = unsafe {
             libbpf_sys::bpf_object__open_mem(
-                object_file.as_ptr() as *const c_void,
+                object_file.as_ptr().cast::<c_void>(),
                 object_file.len() as c_ulong,
                 &obj_opts,
             )

libbpf-rs/src/iter.rs

@@ -36,7 +36,7 @@ impl Iter {
 impl io::Read for Iter {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         let bytes_read =
-            unsafe { libc::read(self.fd.as_raw_fd(), buf.as_mut_ptr() as *mut _, buf.len()) };
+            unsafe { libc::read(self.fd.as_raw_fd(), buf.as_mut_ptr().cast(), buf.len()) };
         if bytes_read < 0 {
             return Err(io::Error::last_os_error());
         }

libbpf-rs/src/linker.rs

@@ -59,7 +59,7 @@ impl Linker {
         let err = unsafe {
             libbpf_sys::bpf_linker__add_buf(
                 self.linker.as_ptr(),
-                buf.as_ptr() as *mut _,
+                buf.as_ptr().cast_mut().cast(),
                 buf.len() as _,
                 opts,
             )

libbpf-rs/src/map.rs

@@ -90,7 +90,7 @@ impl<'obj> OpenMap<'obj> {
     fn initial_value_raw(&self) -> (*mut u8, usize) {
         let mut size = 0u64;
         let ptr = unsafe {
-            libbpf_sys::bpf_map__initial_value(self.ptr.as_ptr(), &mut size as *mut _ as _)
+            libbpf_sys::bpf_map__initial_value(self.ptr.as_ptr(), (&raw mut size).cast())
         };
         (ptr.cast(), size as _)
     }
@@ -149,7 +149,7 @@ impl<'obj> OpenMapMut<'obj> {
         let ret = unsafe {
             libbpf_sys::bpf_map__set_initial_value(
                 self.ptr.as_ptr(),
-                data.as_ptr() as *const c_void,
+                data.as_ptr().cast::<c_void>(),
                 data.len() as libbpf_sys::size_t,
             )
         };
@@ -317,7 +317,7 @@ where
         return ptr::null();
     }
 
-    key.as_ptr() as *const c_void
+    key.as_ptr().cast::<c_void>()
 }
 
 /// Internal function to perform a map lookup and write the value into raw pointer.
@@ -414,7 +414,7 @@ where
         libbpf_sys::bpf_map_update_elem(
             map.as_fd().as_raw_fd(),
             map_key(map, key),
-            value.as_ptr() as *const c_void,
+            value.as_ptr().cast::<c_void>(),
             flags.bits(),
         )
     };
@@ -605,7 +605,7 @@ pub trait MapCore: Debug + AsFd + private::Sealed {
             libbpf_sys::bpf_map_lookup_elem(
                 self.as_fd().as_raw_fd(),
                 ptr::null(),
-                value.to_vec().as_mut_ptr() as *mut c_void,
+                value.to_vec().as_mut_ptr().cast::<c_void>(),
             )
         };
 
@@ -661,7 +661,7 @@ pub trait MapCore: Debug + AsFd + private::Sealed {
         };
 
         let ret = unsafe {
-            libbpf_sys::bpf_map_delete_elem(self.as_fd().as_raw_fd(), key.as_ptr() as *const c_void)
+            libbpf_sys::bpf_map_delete_elem(self.as_fd().as_raw_fd(), key.as_ptr().cast::<c_void>())
         };
         util::parse_ret(ret)
     }
@@ -698,7 +698,7 @@ pub trait MapCore: Debug + AsFd + private::Sealed {
         let ret = unsafe {
             libbpf_sys::bpf_map_delete_batch(
                 self.as_fd().as_raw_fd(),
-                keys.as_ptr() as *const c_void,
+                keys.as_ptr().cast::<c_void>(),
                 &mut count,
                 &opts as *const libbpf_sys::bpf_map_batch_opts,
             )
@@ -727,7 +727,7 @@ pub trait MapCore: Debug + AsFd + private::Sealed {
             libbpf_sys::bpf_map_lookup_and_delete_elem(
                 self.as_fd().as_raw_fd(),
                 map_key(self, key),
-                out.as_mut_ptr() as *mut c_void,
+                out.as_mut_ptr().cast::<c_void>(),
             )
         };
 
@@ -814,8 +814,8 @@ pub trait MapCore: Debug + AsFd + private::Sealed {
         let ret = unsafe {
             libbpf_sys::bpf_map_update_batch(
                 self.as_fd().as_raw_fd(),
-                keys.as_ptr() as *const c_void,
-                values.as_ptr() as *const c_void,
+                keys.as_ptr().cast::<c_void>(),
+                values.as_ptr().cast::<c_void>(),
                 &mut count,
                 &opts as *const libbpf_sys::bpf_map_batch_opts,
             )
@@ -1571,8 +1571,8 @@ impl Iterator for MapKeyIter<'_> {
         let ret = unsafe {
             libbpf_sys::bpf_map_get_next_key(
                 self.map_fd.as_raw_fd(),
-                prev as _,
-                self.next.as_mut_ptr() as _,
+                prev.cast(),
+                self.next.as_mut_ptr().cast(),
             )
         };
         if ret != 0 {
@@ -1717,7 +1717,7 @@ impl MapInfo {
         let () = util::parse_ret(unsafe {
             bpf_obj_get_info_by_fd(
                 fd.as_raw_fd(),
-                &mut map_info as *mut bpf_map_info as *mut c_void,
+                (&mut map_info as *mut bpf_map_info).cast::<c_void>(),
                 &mut size as *mut u32,
             )
         })?;

libbpf-rs/src/object.rs

@@ -227,7 +227,7 @@ impl ObjectBuilder {
         let opts_ptr = self.as_libbpf_object().as_ptr();
         let ptr = unsafe {
             libbpf_sys::bpf_object__open_mem(
-                mem.as_ptr() as *const c_void,
+                mem.as_ptr().cast::<c_void>(),
                 mem.len() as libbpf_sys::size_t,
                 opts_ptr,
             )
@@ -289,7 +289,7 @@ impl OpenObject {
         // SAFETY: We ensured `ptr` is valid during construction.
         let name_ptr = unsafe { libbpf_sys::bpf_object__name(self.ptr.as_ptr()) };
         // SAFETY: `libbpf_get_error` is always safe to call.
-        let err = unsafe { libbpf_sys::libbpf_get_error(name_ptr as *const _) };
+        let err = unsafe { libbpf_sys::libbpf_get_error(name_ptr.cast()) };
         if err != 0 {
             return None
         }
@@ -389,7 +389,7 @@ impl Object {
         // SAFETY: We ensured `ptr` is valid during construction.
         let name_ptr = unsafe { libbpf_sys::bpf_object__name(self.ptr.as_ptr()) };
         // SAFETY: `libbpf_get_error` is always safe to call.
-        let err = unsafe { libbpf_sys::libbpf_get_error(name_ptr as *const _) };
+        let err = unsafe { libbpf_sys::libbpf_get_error(name_ptr.cast()) };
         if err != 0 {
             return None
         }

libbpf-rs/src/perf_buffer.rs

@@ -142,7 +142,7 @@ where
                 self.pages as libbpf_sys::size_t,
                 c_sample_cb,
                 c_lost_cb,
-                callback_struct_ptr as *mut _,
+                callback_struct_ptr.cast(),
                 ptr::null(),
             )
         };
@@ -155,7 +155,7 @@ where
     }
 
     unsafe extern "C" fn call_sample_cb(ctx: *mut c_void, cpu: i32, data: *mut c_void, size: u32) {
-        let callback_struct = ctx as *mut CbStruct<'_>;
+        let callback_struct = ctx.cast::<CbStruct<'_>>();
 
         if let Some(cb) = unsafe { &mut (*callback_struct).sample_cb } {
             let slice = unsafe { slice::from_raw_parts(data as *const u8, size as usize) };
@@ -164,7 +164,7 @@ where
     }
 
     unsafe extern "C" fn call_lost_cb(ctx: *mut c_void, cpu: i32, count: u64) {
-        let callback_struct = ctx as *mut CbStruct<'_>;
+        let callback_struct = ctx.cast::<CbStruct<'_>>();
 
         if let Some(cb) = unsafe { &mut (*callback_struct).lost_cb } {
             cb(cpu, count);

libbpf-rs/src/program.rs

@@ -815,7 +815,7 @@ impl<'obj> Program<'obj> {
         let ret = unsafe {
             libbpf_sys::bpf_obj_get_info_by_fd(
                 fd.as_raw_fd(),
-                prog_info_ptr as *mut c_void,
+                prog_info_ptr.cast::<c_void>(),
                 &mut len,
             )
         };
@@ -1244,7 +1244,7 @@ impl<'obj> ProgramMut<'obj> {
 
         let opts = libbpf_sys::bpf_kprobe_multi_opts {
             sz: size_of::<libbpf_sys::bpf_kprobe_multi_opts>() as _,
-            syms: syms.as_mut_ptr() as _,
+            syms: syms.as_mut_ptr().cast(),
             cnt: cnt as libbpf_sys::size_t,
             retprobe,
             // bpf_kprobe_multi_opts might have padding fields on some platform
@@ -1275,9 +1275,9 @@ impl<'obj> ProgramMut<'obj> {
 
         let opts = libbpf_sys::bpf_kprobe_multi_opts {
             sz: size_of::<libbpf_sys::bpf_kprobe_multi_opts>() as _,
-            syms: syms.as_mut_ptr() as _,
+            syms: syms.as_mut_ptr().cast(),
             cookies: if !cookies.is_empty() {
-                cookies.as_mut_ptr() as _
+                cookies.as_mut_ptr().cast()
             } else {
                 ptr::null()
             },
@@ -1327,7 +1327,7 @@ impl<'obj> ProgramMut<'obj> {
                 self.ptr.as_ptr(),
                 tp_category_ptr,
                 tp_name_ptr,
-                opts as *const _,
+                opts.cast(),
             )
         };