allocator and linux signal cleanup in platform

src/platform/allocator/sys.rs

@@ -27,7 +27,7 @@ unsafe impl Allocator for System {
     fn alloc(&self, size: usize) -> (*mut u8, usize, u32) {
         let Ok(addr) = (unsafe {
             Sys::mmap(
-                0 as *mut _,
+                ptr::null_mut(),
                 size,
                 sys_mman::PROT_WRITE | sys_mman::PROT_READ,
                 sys_mman::MAP_ANON | sys_mman::MAP_PRIVATE,
@@ -37,30 +37,30 @@ unsafe impl Allocator for System {
         }) else {
             return (ptr::null_mut(), 0, 0);
         };
-        (addr as *mut u8, size, 0)
+        (addr.cast::<u8>(), size, 0)
     }
 
     fn remap(&self, ptr: *mut u8, oldsize: usize, newsize: usize, can_move: bool) -> *mut u8 {
         let flags = if can_move { MREMAP_MAYMOVE } else { 0 };
         let Ok(ptr) =
-            (unsafe { Sys::mremap(ptr as *mut _, oldsize, newsize, flags, ptr::null_mut()) })
+            (unsafe { Sys::mremap(ptr.cast(), oldsize, newsize, flags, ptr::null_mut()) })
         else {
             return ptr::null_mut();
         };
-        ptr as *mut u8
+        ptr.cast::<u8>()
     }
 
     fn free_part(&self, ptr: *mut u8, oldsize: usize, newsize: usize) -> bool {
         unsafe {
-            if Sys::mremap(ptr as *mut _, oldsize, newsize, 0, ptr::null_mut()).is_ok() {
+            if Sys::mremap(ptr.cast(), oldsize, newsize, 0, ptr::null_mut()).is_ok() {
                 return true;
             }
-            Sys::munmap(ptr.add(newsize) as *mut _, oldsize - newsize).is_ok()
+            Sys::munmap(ptr.add(newsize).cast(), oldsize - newsize).is_ok()
         }
     }
 
     fn free(&self, ptr: *mut u8, size: usize) -> bool {
-        unsafe { Sys::munmap(ptr as *mut _, size).is_ok() }
+        unsafe { Sys::munmap(ptr.cast(), size).is_ok() }
     }
 
     fn can_release_part(&self, _flags: u32) -> bool {