Implement anonymous fmap

src/syscall/validate.rs

@@ -31,6 +31,16 @@ fn validate(address: usize, size: usize, writable: bool) -> Result<()> {
     Ok(())
 }
 
+/// Convert a pointer and length to reference, if valid
+pub unsafe fn validate_ref<T>(ptr: *const T, size: usize) -> Result<&'static T> {
+    if size == mem::size_of::<T>() {
+        validate(ptr as usize, mem::size_of::<T>(), false)?;
+        Ok(unsafe { &*ptr })
+    } else {
+        Err(Error::new(EINVAL))
+    }
+}
+
 /// Convert a pointer and length to slice, if valid
 //TODO: Mark unsafe
 pub fn validate_slice<T>(ptr: *const T, len: usize) -> Result<&'static [T]> {