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