| // Copyright 2018 The Rust Project Developers. See the COPYRIGHT |
| // file at the top-level directory of this distribution and at |
| // http://rust-lang.org/COPYRIGHT. |
| // |
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or |
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license |
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your |
| // option. This file may not be copied, modified, or distributed |
| // except according to those terms. |
| |
| /// This macro creates a zero-overhead &CStr by adding a NUL terminator to |
| /// the string literal passed into it at compile-time. Use it like: |
| /// |
| /// ``` |
| /// let some_const_cstr = const_cstr!("abc"); |
| /// ``` |
| /// |
| /// The above is roughly equivalent to: |
| /// |
| /// ``` |
| /// let some_const_cstr = CStr::from_bytes_with_nul(b"abc\0").unwrap() |
| /// ``` |
| /// |
| /// Note that macro only checks the string literal for internal NULs if |
| /// debug-assertions are enabled in order to avoid runtime overhead in release |
| /// builds. |
| #[macro_export] |
| macro_rules! const_cstr { |
| ($s:expr) => ({ |
| use std::ffi::CStr; |
| |
| let str_plus_nul = concat!($s, "\0"); |
| |
| if cfg!(debug_assertions) { |
| CStr::from_bytes_with_nul(str_plus_nul.as_bytes()).unwrap() |
| } else { |
| unsafe { |
| CStr::from_bytes_with_nul_unchecked(str_plus_nul.as_bytes()) |
| } |
| } |
| }) |
| } |