From f0b3d5166ef1255fac880b146875ef46d2599a13 Mon Sep 17 00:00:00 2001
From: Matthias Schiffer <mschiffer@universe-factory.net>
Date: Sat, 4 Apr 2020 13:22:18 +0200
Subject: Reorganize

---
 safe_libc/src/boxed.rs | 146 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 146 insertions(+)
 create mode 100644 safe_libc/src/boxed.rs

(limited to 'safe_libc/src/boxed.rs')

diff --git a/safe_libc/src/boxed.rs b/safe_libc/src/boxed.rs
new file mode 100644
index 0000000..72c961c
--- /dev/null
+++ b/safe_libc/src/boxed.rs
@@ -0,0 +1,146 @@
+use crate::util;
+
+use core::{mem, ptr};
+use core::ops::{Deref, DerefMut};
+
+fn alloc<T>(len: usize) -> *mut T {
+	if util::zst::<T>(len) {
+		return ptr::null_mut();
+	}
+	let size = len.checked_mul(mem::size_of::<T>()).expect("allocation overflow");
+	let align = mem::align_of::<T>();
+	util::must_succeed(
+		unsafe {
+			libc::memalign(align as libc::size_t, size as libc::size_t) as *mut T
+		}
+	)
+}
+
+#[inline]
+fn dangling<T>() -> *mut T {
+	mem::align_of::<T>() as *mut T
+}
+
+#[inline]
+fn slice_len<T>(p: *const [T]) -> usize {
+	unsafe { mem::transmute::<*const [T], [usize; 2]>(p)[1] }
+}
+
+pub struct CBox<T: ?Sized>(*mut T);
+
+impl<T: ?Sized> CBox<T> {
+	#[inline]
+	pub unsafe fn from_raw_unchecked(p: *mut T) -> CBox<T> {
+		CBox(p)
+	}
+
+	#[inline]
+	pub fn into_raw(self) -> *mut T {
+		let p = self.0;
+		mem::forget(self);
+		p
+	}
+
+	#[inline]
+	pub fn as_ptr(&self) -> *const T {
+		self.0
+	}
+
+	#[inline]
+	pub fn as_mut_ptr(&mut self) -> *mut T {
+		self.0
+	}
+}
+
+impl<T> CBox<T> {
+	#[inline]
+	pub fn new(value: T) -> CBox<T> {
+		let p = alloc(1);
+		unsafe {
+			ptr::write(p, value);
+			CBox::from_raw_unchecked(p)
+		}
+	}
+
+	#[inline]
+	pub unsafe fn from_raw(p: *mut T) -> CBox<T> {
+		util::check_ptr(p, 1);
+		CBox(p)
+	}
+
+	#[inline]
+	pub unsafe fn slice_from_raw_parts_unchecked(p: *mut T, len: usize) -> CBox<[T]> {
+		CBox(ptr::slice_from_raw_parts_mut(p, len))
+	}
+
+	#[inline]
+	pub unsafe fn slice_from_raw_parts(p: *mut T, len: usize) -> CBox<[T]> {
+		util::check_ptr(p, len);
+		CBox::slice_from_raw_parts_unchecked(p, len)
+	}
+
+	#[inline]
+	fn safe_ptr(&self) -> *mut T {
+		if util::zst::<T>(1) {
+			return dangling();
+		}
+
+		debug_assert!(!self.0.is_null(), "NULL ptr");
+		self.0
+	}
+}
+
+impl<T> CBox<[T]> {
+	#[inline]
+	fn safe_ptr(&self) -> *mut [T] {
+		if self.0.is_null() {
+			let len = slice_len(self.0);
+			debug_assert!(util::zst::<T>(len), "NULL ptr");
+			return ptr::slice_from_raw_parts_mut(dangling(), len);
+		}
+
+		self.0
+	}
+}
+
+impl<T: ?Sized> Drop for CBox<T> {
+	#[inline]
+	fn drop(&mut self) {
+		unsafe {
+			ptr::drop_in_place(self.0);
+			libc::free(self.0 as *mut libc::c_void);
+		}
+	}
+}
+
+impl<T> Deref for CBox<T> {
+	type Target = T;
+
+	#[inline]
+	fn deref(&self) -> &T {
+		unsafe { &*self.safe_ptr() }
+	}
+}
+
+impl<T> DerefMut for CBox<T> {
+	#[inline]
+	fn deref_mut(&mut self) -> &mut T {
+		unsafe { &mut *self.safe_ptr() }
+	}
+}
+
+impl<T> Deref for CBox<[T]> {
+	type Target = [T];
+
+	#[inline]
+	fn deref(&self) -> &[T] {
+		unsafe { &*self.safe_ptr() }
+	}
+}
+
+impl<T> DerefMut for CBox<[T]> {
+	#[inline]
+	fn deref_mut(&mut self) -> &mut [T] {
+		unsafe { &mut *self.safe_ptr() }
+	}
+}
-- 
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