feat: add error message to creating memfd

src/bump_allocator.rs

@@ -3,7 +3,7 @@ use std::{
     usize,
 };
 
-use libc::{c_char, c_void, ftruncate, memfd_create, mmap, MAP_FAILED, MAP_SHARED, PROT_READ, PROT_WRITE};
+use libc::{c_char, c_void, ftruncate, mmap, perror, syscall, SYS_memfd_secret, MAP_FAILED, MAP_SHARED, PROT_READ, PROT_WRITE};
 
 pub(crate) const MEMFD_INITIAL_SIZE: usize = 1024 * 1024;
 const MMAP_SIZE: usize = 1024 * 1024;
@@ -26,7 +26,10 @@ impl BumpAllocator {
     unsafe fn new() -> Self {
         assert!(MMAP_SIZE >= MEMFD_INITIAL_SIZE);
 
-        let data_fd = memfd_create("data\x00".as_ptr() as *const c_char, 0);
+        let data_fd = syscall(SYS_memfd_secret, 0) as i32;
+        if data_fd <= 0 {
+            perror("memfd secret\x00".as_ptr() as *const c_char);
+        }
 
         assert!(data_fd > 0);
 

src/sharedptr.rs

@@ -1,24 +1,21 @@
 use core::slice;
-use std::{
-    ops::{Deref, DerefMut},
-    usize,
-};
+use std::ops::{Deref, DerefMut};
 
 use crate::allocator::ALLOCATOR;
 
 #[derive(Debug)]
-pub struct SharedPtr<'a, const N: usize>(&'a mut [u8; N]);
+pub struct SharedPtr<const N: usize>(*mut u8);
 
-impl<const N: usize> SharedPtr<'_, N> {
+unsafe impl<const N: usize> Send for SharedPtr<N> {}
+unsafe impl<const N: usize> Sync for SharedPtr<N> {}
+
+impl<const N: usize> SharedPtr<N> {
     pub fn new() -> Option<Self> {
         let mut allocator = ALLOCATOR.lock().unwrap();
 
-        let buf = unsafe {
-            let buf = allocator.allocate(N)?;
-            slice::from_raw_parts_mut(buf, N)
-        };
+        let buf = unsafe { allocator.allocate(N)? };
 
-        Some(SharedPtr(buf.try_into().expect("Should never fail")))
+        Some(SharedPtr(buf))
     }
 
     pub fn get_offset(&self) -> usize {
@@ -28,26 +25,34 @@ impl<const N: usize> SharedPtr<'_, N> {
     }
 }
 
-impl<'a, const N: usize> Deref for SharedPtr<'a, N> {
+impl<const N: usize> Deref for SharedPtr<N> {
     type Target = [u8; N];
 
     fn deref(&self) -> &Self::Target {
-        &self.0
+        unsafe {
+            slice::from_raw_parts(self.0, N)
+                .try_into()
+                .expect("This should never fail")
+        }
     }
 }
 
-impl<'a, const N: usize> DerefMut for SharedPtr<'a, N> {
+impl<const N: usize> DerefMut for SharedPtr<N> {
     fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.0
+        unsafe {
+            slice::from_raw_parts_mut(self.0, N)
+                .try_into()
+                .expect("This should never fail")
+        }
     }
 }
 
-impl<const N: usize> Drop for SharedPtr<'_, N> {
+impl<const N: usize> Drop for SharedPtr<N> {
     fn drop(&mut self) {
         let mut allocator = ALLOCATOR.lock().unwrap();
 
         unsafe {
-            allocator.deallocate(self.0.as_mut_ptr());
+            allocator.deallocate(self.0);
         }
     }
 }