Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

1 files changed, 82 insertions, 0 deletions

diff --git a/vendor/rustix/src/utils.rs b/vendor/rustix/src/utils.rs
new file mode 100644
index 0000000..d21ed88
--- /dev/null
+++ b/vendor/rustix/src/utils.rs
@@ -0,0 +1,82 @@
+//! Miscellaneous minor utilities.
+
+#![allow(dead_code)]
+#![allow(unused_macros)]
+
+use core::ffi::c_void;
+use core::mem::{align_of, size_of};
+use core::ptr::{null, null_mut, NonNull};
+
+/// Convert a `&T` into a `*const T` without using an `as`.
+#[inline]
+pub(crate) const fn as_ptr<T>(t: &T) -> *const T {
+    t
+}
+
+/// Convert a `&mut T` into a `*mut T` without using an `as`.
+#[inline]
+pub(crate) fn as_mut_ptr<T>(t: &mut T) -> *mut T {
+    t
+}
+
+/// Convert an `Option<&T>` into a possibly-null `*const T`.
+#[inline]
+pub(crate) const fn option_as_ptr<T>(t: Option<&T>) -> *const T {
+    match t {
+        Some(t) => t,
+        None => null(),
+    }
+}
+
+/// Convert an `Option<&mut T>` into a possibly-null `*mut T`.
+#[inline]
+pub(crate) fn option_as_mut_ptr<T>(t: Option<&mut T>) -> *mut T {
+    match t {
+        Some(t) => t,
+        None => null_mut(),
+    }
+}
+
+/// Convert a `*mut c_void` to a `*mut T`, checking that it is not null,
+/// misaligned, or pointing to a region of memory that wraps around the address
+/// space.
+pub(crate) fn check_raw_pointer<T>(value: *mut c_void) -> Option<NonNull<T>> {
+    if (value as usize).checked_add(size_of::<T>()).is_none()
+        || (value as usize) % align_of::<T>() != 0
+    {
+        return None;
+    }
+
+    NonNull::new(value.cast())
+}
+
+/// Create an array value containing all default values, inferring the type.
+#[inline]
+pub(crate) fn default_array<T: Default + Copy, const N: usize>() -> [T; N] {
+    [T::default(); N]
+}
+
+/// Create a union value containing a default value in one of its arms.
+///
+/// The field names a union field which must have the same size as the union
+/// itself.
+macro_rules! default_union {
+    ($union:ident, $field:ident) => {{
+        let u = $union {
+            $field: Default::default(),
+        };
+
+        // Assert that the given field initializes the whole union.
+        #[cfg(test)]
+        unsafe {
+            let field_value = u.$field;
+            assert_eq!(
+                core::mem::size_of_val(&u),
+                core::mem::size_of_val(&field_value)
+            );
+            const_assert_eq!(memoffset::offset_of_union!($union, $field), 0);
+        }
+
+        u
+    }};
+}