Safe libc test code

.gitignore

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+/target
+**/*.rs.bk

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+[[package]]
+name = "libc"
+version = "0.2.54"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "neco"
+version = "0.1.0"
+dependencies = [
+ "libc 0.2.54 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[metadata]
+"checksum libc 0.2.54 (registry+https://github.com/rust-lang/crates.io-index)" = "c6785aa7dd976f5fbf3b71cfd9cd49d7f783c1ff565a858d71031c6c313aa5c6"

Cargo.toml

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+[package]
+name = "neco"
+version = "0.1.0"
+authors = ["Matthias Schiffer <mschiffer@universe-factory.net>"]
+edition = "2018"
+
+[dependencies]
+libc = { version = "0.2.54", default-features = false }
+
+[profile.dev]
+panic = "abort"
+
+[profile.release]
+panic = "abort"

src/c/mod.rs

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+pub mod posix;
+pub mod string;

src/c/posix.rs

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+extern "C" {
+	pub fn strndup(cs: *const libc::c_char, n: libc::size_t) -> *mut libc::c_char;
+
+	pub static mut stdin: *mut libc::FILE;
+	pub static mut stdout: *mut libc::FILE;
+	pub static mut stderr: *mut libc::FILE;
+
+}

src/c/string.rs

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+use super::posix;
+use core::{mem, ptr, slice};
+use core::ops::{Deref, DerefMut};
+
+const SENTINEL: *mut libc::c_void = 1 as *mut libc::c_void;
+
+fn must_succeed<T>(p: *mut T) -> *mut T {
+	if p.is_null() {
+		panic!("allocation failure");
+	}
+	p
+}
+
+unsafe fn malloc<T>() -> *mut T {
+	let size = mem::size_of::<T>();
+	/*if size == 0 {
+		return SENTINEL as *mut T;
+	}*/
+	must_succeed(0 as *mut T)
+	/*must_succeed(
+		libc::memalign(mem::align_of::<T>() as libc::size_t, size as libc::size_t)
+	) as *mut T*/
+}
+
+pub struct CBox<T: ?Sized>(*mut T);
+
+impl<T: ?Sized> CBox<T> {
+	pub const unsafe fn from_raw(p: *mut T) -> CBox<T> {
+		CBox(p)
+	}
+
+	pub fn into_raw(self) -> *mut T {
+		let p = self.0;
+		mem::forget(self);
+		p
+	}
+
+	pub const fn as_ptr(&self) -> *const T {
+		self.0
+	}
+
+	pub fn as_mut_ptr(&mut self) -> *mut T {
+		self.0
+	}
+}
+
+impl<T> CBox<T> {
+	pub fn new(value: T) -> CBox<T> {
+		unsafe {
+			let p = malloc();
+			ptr::write(p, value);
+			CBox::from_raw(p)
+		}
+	}
+}
+
+impl<T: ?Sized> Drop for CBox<T> {
+	fn drop(&mut self) {
+		let p = self.0 as *mut libc::c_void;
+		if p != SENTINEL {
+			unsafe { libc::free(p); }
+		}
+	}
+}
+
+impl<T: ?Sized> Deref for CBox<T> {
+	type Target = T;
+
+	fn deref(&self) -> &T {
+		unsafe { &*self.0 }
+	}
+}
+
+impl<T: ?Sized> DerefMut for CBox<T> {
+	fn deref_mut(&mut self) -> &mut T {
+		unsafe { &mut *self.0 }
+	}
+}
+
+//pub struct FromBytesWithNulError {}
+
+pub struct CStr { inner: libc::c_char }
+
+impl CStr {
+	pub unsafe fn from_ptr<'a>(p: *const libc::c_char) -> &'a CStr {
+		&*(p as *const CStr)
+	}
+
+	pub unsafe fn from_ptr_mut<'a>(p: *mut libc::c_char) -> &'a mut CStr {
+		&mut *(p as *mut CStr)
+	}
+
+	pub unsafe fn from_bytes_with_nul_unchecked(bytes: &[u8]) -> &CStr {
+		CStr::from_ptr(bytes.as_ptr() as *const libc::c_char)
+	}
+
+	// TODO
+	//pub fn from_bytes_with_nul(bytes: &[u8]) -> Result<&CStr, FromBytesWithNulError> {
+	//}
+
+	pub fn len(&self) -> usize {
+		unsafe { libc::strlen(self.as_ptr()) as usize }
+	}
+
+	pub const fn as_ptr(&self) -> *const libc::c_char {
+		&self.inner
+	}
+
+	pub fn as_mut_ptr(&mut self) -> *mut libc::c_char {
+		&mut self.inner
+	}
+
+	pub fn as_bytes(&self) -> &[u8] {
+		unsafe { slice::from_raw_parts(
+			self.as_ptr() as *const u8,
+			self.len(),
+		) }
+	}
+
+	pub fn as_bytes_mut(&mut self) -> &mut [u8] {
+		unsafe { slice::from_raw_parts_mut(
+			self.as_mut_ptr() as *mut u8,
+			self.len(),
+		) }
+	}
+
+	pub fn to_owned(self: &CStr) -> CString {
+		CString::from(self)
+	}
+}
+
+#[macro_export]
+macro_rules! cstr {
+	($s:expr) => (
+		unsafe { $crate::c::string::CStr::from_bytes_with_nul_unchecked(concat!($s, "\0").as_bytes()) }
+	)
+}
+
+pub struct CString { inner: CBox<libc::c_char> }
+
+impl CString {
+	pub unsafe fn from_raw(p: *mut libc::c_char) -> CString {
+		CString { inner: CBox::from_raw(p) }
+	}
+
+	pub fn into_raw(self) -> *mut libc::c_char {
+		self.inner.into_raw()
+	}
+}
+
+impl Deref for CString {
+	type Target = CStr;
+
+	fn deref(&self) -> &CStr {
+		unsafe { CStr::from_ptr(&*self.inner) }
+	}
+}
+
+impl DerefMut for CString {
+	fn deref_mut(&mut self) -> &mut CStr {
+		unsafe { CStr::from_ptr_mut(&mut *self.inner) }
+	}
+}
+
+impl From<&[u8]> for CString {
+	fn from(s: &[u8]) -> CString {
+		unsafe {
+			CString::from_raw(must_succeed(posix::strndup(
+				s.as_ptr() as *const libc::c_char,
+				s.len() as libc::size_t,
+			)))
+		}
+	}
+}
+
+impl From<&str> for CString {
+	fn from(s: &str) -> CString {
+		CString::from(s.as_bytes())
+	}
+}
+
+impl From<&CStr> for CString {
+	fn from(s: &CStr) -> CString {
+		unsafe {
+			CString::from_raw(must_succeed(libc::strdup(s.as_ptr())))
+		}
+	}
+}

src/main.rs

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+#![no_main]
+#![no_std]
+
+extern crate libc;
+
+mod c;
+
+#[no_mangle]
+pub extern fn main(_nargs: libc::c_int, _args: *const *const libc::c_char) -> libc::c_int {
+	let foo = cstr!("Foo! %p\n");
+	let x = c::string::CBox::new(());
+	unsafe { libc::printf(foo.as_ptr(), &*x as *const ()); }
+	0
+}
+
+#[panic_handler]
+fn panic(_info: &core::panic::PanicInfo) -> ! {
+	unsafe { libc::abort() }
+}