tweak default impls

Author: newpavlov

src/default_impls.rs

@@ -2,45 +2,46 @@
 use crate::Error;
 use core::{mem::MaybeUninit, slice};
 
-/// Default implementation of `inner_u32` on top of `getrandom::fill_uninit`
-pub fn u32() -> Result<u32, Error> {
-    let mut res = MaybeUninit::<u32>::uninit();
+#[inline(always)]
+#[allow(unused_unsafe)]
+unsafe fn default_impl<T>(secure: bool) -> Result<T, Error> {
+    let mut res = MaybeUninit::<T>::uninit();
     // SAFETY: the created slice has the same size as `res`
     let dst = unsafe {
         let p: *mut MaybeUninit<u8> = res.as_mut_ptr().cast();
-        slice::from_raw_parts_mut(p, core::mem::size_of::<u32>())
+        slice::from_raw_parts_mut(p, core::mem::size_of::<T>())
     };
-    crate::fill_uninit(dst)?;
+    if secure {
+        crate::fill_uninit(dst)?;
+    } else {
+        crate::insecure_fill_uninit(dst)?;
+    }
     // SAFETY: `dst` has been fully initialized by `imp::fill_inner`
     // since it returned `Ok`.
     Ok(unsafe { res.assume_init() })
 }
 
+/// Default implementation of `inner_u32` on top of `getrandom::fill_uninit`
+pub fn u32() -> Result<u32, Error> {
+    unsafe { default_impl(true) }
+}
+
 /// Default implementation of `inner_u64` on top of `getrandom::fill_uninit`
 pub fn u64() -> Result<u64, Error> {
-    let mut res = MaybeUninit::<u64>::uninit();
-    // SAFETY: the created slice has the same size as `res`
-    let dst = unsafe {
-        let p: *mut MaybeUninit<u8> = res.as_mut_ptr().cast();
-        slice::from_raw_parts_mut(p, core::mem::size_of::<u64>())
-    };
-    crate::fill_uninit(dst)?;
-    // SAFETY: `dst` has been fully initialized by `imp::fill_inner`
-    // since it returned `Ok`.
-    Ok(unsafe { res.assume_init() })
+    unsafe { default_impl(true) }
 }
 
 /// Default implementation of `insecure_fill_inner` on top of `getrandom::fill_uninit`
 pub fn insecure_fill_uninit(dst: &mut [MaybeUninit<u8>]) -> Result<(), Error> {
     crate::fill_uninit(dst).map(|_| ())
 }
 
-/// Default implementation of `inner_u32` on top of `getrandom::u32`
+/// Default implementation of `inner_u32` on top of `getrandom::insecure_fill_uninit`
 pub fn insecure_u32() -> Result<u32, Error> {
-    crate::u32()
+    unsafe { default_impl(false) }
 }
 
-/// Default implementation of `inner_insecure_u64` on top of `getrandom::u64`
+/// Default implementation of `inner_insecure_u64` on top of `getrandom::insecure_fill_uninit`
 pub fn insecure_u64() -> Result<u64, Error> {
-    crate::u64()
+    unsafe { default_impl(false) }
 }