Implement the typical use of waitpid

kernel/syscall/validate.rs

@@ -0,0 +1,15 @@
+use core::slice;
+
+use super::Result;
+
+/// Convert a pointer and length to slice, if valid
+/// TODO: Check validity
+pub fn validate_slice<T>(ptr: *const T, len: usize) -> Result<&'static [T]> {
+    Ok(unsafe { slice::from_raw_parts(ptr, len) })
+}
+
+/// Convert a pointer and length to slice, if valid
+/// TODO: Check validity
+pub fn validate_slice_mut<T>(ptr: *mut T, len: usize) -> Result<&'static mut [T]> {
+    Ok(unsafe { slice::from_raw_parts_mut(ptr, len) })
+}