├── .gitignore ├── Cargo.toml ├── LICENSE-APACHE ├── LICENSE-MIT ├── README.md └── src └── lib.rs /.gitignore: -------------------------------------------------------------------------------- 1 | target 2 | Cargo.lock 3 | *.swp 4 | .idea/ 5 | *.iml 6 | -------------------------------------------------------------------------------- /Cargo.toml: -------------------------------------------------------------------------------- 1 | [package] 2 | name = "const-cstr" 3 | version = "0.3.0" 4 | authors = ["Austin Bonander "] 5 | description = "Create static C-compatible strings from Rust string literals." 6 | license = "MIT OR Apache-2.0" 7 | repository = "https://github.com/cybergeek94/const-cstr" 8 | 9 | -------------------------------------------------------------------------------- /LICENSE-APACHE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. Definitions. 8 | 9 | "License" shall mean the terms and conditions for use, reproduction, 10 | and distribution as defined by Sections 1 through 9 of this document. 11 | 12 | "Licensor" shall mean the copyright owner or entity authorized by 13 | the copyright owner that is granting the License. 14 | 15 | "Legal Entity" shall mean the union of the acting entity and all 16 | other entities that control, are controlled by, or are under common 17 | control with that entity. For the purposes of this definition, 18 | "control" means (i) the power, direct or indirect, to cause the 19 | direction or management of such entity, whether by contract or 20 | otherwise, or (ii) ownership of fifty percent (50%) or more of the 21 | outstanding shares, or (iii) beneficial ownership of such entity. 22 | 23 | "You" (or "Your") shall mean an individual or Legal Entity 24 | exercising permissions granted by this License. 25 | 26 | "Source" form shall mean the preferred form for making modifications, 27 | including but not limited to software source code, documentation 28 | source, and configuration files. 29 | 30 | "Object" form shall mean any form resulting from mechanical 31 | transformation or translation of a Source form, including but 32 | not limited to compiled object code, generated documentation, 33 | and conversions to other media types. 34 | 35 | "Work" shall mean the work of authorship, whether in Source or 36 | Object form, made available under the License, as indicated by a 37 | copyright notice that is included in or attached to the work 38 | (an example is provided in the Appendix below). 39 | 40 | "Derivative Works" shall mean any work, whether in Source or Object 41 | form, that is based on (or derived from) the Work and for which the 42 | editorial revisions, annotations, elaborations, or other modifications 43 | represent, as a whole, an original work of authorship. For the purposes 44 | of this License, Derivative Works shall not include works that remain 45 | separable from, or merely link (or bind by name) to the interfaces of, 46 | the Work and Derivative Works thereof. 47 | 48 | "Contribution" shall mean any work of authorship, including 49 | the original version of the Work and any modifications or additions 50 | to that Work or Derivative Works thereof, that is intentionally 51 | submitted to Licensor for inclusion in the Work by the copyright owner 52 | or by an individual or Legal Entity authorized to submit on behalf of 53 | the copyright owner. For the purposes of this definition, "submitted" 54 | means any form of electronic, verbal, or written communication sent 55 | to the Licensor or its representatives, including but not limited to 56 | communication on electronic mailing lists, source code control systems, 57 | and issue tracking systems that are managed by, or on behalf of, the 58 | Licensor for the purpose of discussing and improving the Work, but 59 | excluding communication that is conspicuously marked or otherwise 60 | designated in writing by the copyright owner as "Not a Contribution." 61 | 62 | "Contributor" shall mean Licensor and any individual or Legal Entity 63 | on behalf of whom a Contribution has been received by Licensor and 64 | subsequently incorporated within the Work. 65 | 66 | 2. Grant of Copyright License. Subject to the terms and conditions of 67 | this License, each Contributor hereby grants to You a perpetual, 68 | worldwide, non-exclusive, no-charge, royalty-free, irrevocable 69 | copyright license to reproduce, prepare Derivative Works of, 70 | publicly display, publicly perform, sublicense, and distribute the 71 | Work and such Derivative Works in Source or Object form. 72 | 73 | 3. Grant of Patent License. Subject to the terms and conditions of 74 | this License, each Contributor hereby grants to You a perpetual, 75 | worldwide, non-exclusive, no-charge, royalty-free, irrevocable 76 | (except as stated in this section) patent license to make, have made, 77 | use, offer to sell, sell, import, and otherwise transfer the Work, 78 | where such license applies only to those patent claims licensable 79 | by such Contributor that are necessarily infringed by their 80 | Contribution(s) alone or by combination of their Contribution(s) 81 | with the Work to which such Contribution(s) was submitted. If You 82 | institute patent litigation against any entity (including a 83 | cross-claim or counterclaim in a lawsuit) alleging that the Work 84 | or a Contribution incorporated within the Work constitutes direct 85 | or contributory patent infringement, then any patent licenses 86 | granted to You under this License for that Work shall terminate 87 | as of the date such litigation is filed. 88 | 89 | 4. Redistribution. You may reproduce and distribute copies of the 90 | Work or Derivative Works thereof in any medium, with or without 91 | modifications, and in Source or Object form, provided that You 92 | meet the following conditions: 93 | 94 | (a) You must give any other recipients of the Work or 95 | Derivative Works a copy of this License; and 96 | 97 | (b) You must cause any modified files to carry prominent notices 98 | stating that You changed the files; and 99 | 100 | (c) You must retain, in the Source form of any Derivative Works 101 | that You distribute, all copyright, patent, trademark, and 102 | attribution notices from the Source form of the Work, 103 | excluding those notices that do not pertain to any part of 104 | the Derivative Works; and 105 | 106 | (d) If the Work includes a "NOTICE" text file as part of its 107 | distribution, then any Derivative Works that You distribute must 108 | include a readable copy of the attribution notices contained 109 | within such NOTICE file, excluding those notices that do not 110 | pertain to any part of the Derivative Works, in at least one 111 | of the following places: within a NOTICE text file distributed 112 | as part of the Derivative Works; within the Source form or 113 | documentation, if provided along with the Derivative Works; or, 114 | within a display generated by the Derivative Works, if and 115 | wherever such third-party notices normally appear. The contents 116 | of the NOTICE file are for informational purposes only and 117 | do not modify the License. You may add Your own attribution 118 | notices within Derivative Works that You distribute, alongside 119 | or as an addendum to the NOTICE text from the Work, provided 120 | that such additional attribution notices cannot be construed 121 | as modifying the License. 122 | 123 | You may add Your own copyright statement to Your modifications and 124 | may provide additional or different license terms and conditions 125 | for use, reproduction, or distribution of Your modifications, or 126 | for any such Derivative Works as a whole, provided Your use, 127 | reproduction, and distribution of the Work otherwise complies with 128 | the conditions stated in this License. 129 | 130 | 5. Submission of Contributions. Unless You explicitly state otherwise, 131 | any Contribution intentionally submitted for inclusion in the Work 132 | by You to the Licensor shall be under the terms and conditions of 133 | this License, without any additional terms or conditions. 134 | Notwithstanding the above, nothing herein shall supersede or modify 135 | the terms of any separate license agreement you may have executed 136 | with Licensor regarding such Contributions. 137 | 138 | 6. Trademarks. This License does not grant permission to use the trade 139 | names, trademarks, service marks, or product names of the Licensor, 140 | except as required for reasonable and customary use in describing the 141 | origin of the Work and reproducing the content of the NOTICE file. 142 | 143 | 7. Disclaimer of Warranty. Unless required by applicable law or 144 | agreed to in writing, Licensor provides the Work (and each 145 | Contributor provides its Contributions) on an "AS IS" BASIS, 146 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or 147 | implied, including, without limitation, any warranties or conditions 148 | of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A 149 | PARTICULAR PURPOSE. You are solely responsible for determining the 150 | appropriateness of using or redistributing the Work and assume any 151 | risks associated with Your exercise of permissions under this License. 152 | 153 | 8. Limitation of Liability. In no event and under no legal theory, 154 | whether in tort (including negligence), contract, or otherwise, 155 | unless required by applicable law (such as deliberate and grossly 156 | negligent acts) or agreed to in writing, shall any Contributor be 157 | liable to You for damages, including any direct, indirect, special, 158 | incidental, or consequential damages of any character arising as a 159 | result of this License or out of the use or inability to use the 160 | Work (including but not limited to damages for loss of goodwill, 161 | work stoppage, computer failure or malfunction, or any and all 162 | other commercial damages or losses), even if such Contributor 163 | has been advised of the possibility of such damages. 164 | 165 | 9. Accepting Warranty or Additional Liability. While redistributing 166 | the Work or Derivative Works thereof, You may choose to offer, 167 | and charge a fee for, acceptance of support, warranty, indemnity, 168 | or other liability obligations and/or rights consistent with this 169 | License. However, in accepting such obligations, You may act only 170 | on Your own behalf and on Your sole responsibility, not on behalf 171 | of any other Contributor, and only if You agree to indemnify, 172 | defend, and hold each Contributor harmless for any liability 173 | incurred by, or claims asserted against, such Contributor by reason 174 | of your accepting any such warranty or additional liability. 175 | 176 | END OF TERMS AND CONDITIONS 177 | 178 | APPENDIX: How to apply the Apache License to your work. 179 | 180 | To apply the Apache License to your work, attach the following 181 | boilerplate notice, with the fields enclosed by brackets "[]" 182 | replaced with your own identifying information. (Don't include 183 | the brackets!) The text should be enclosed in the appropriate 184 | comment syntax for the file format. We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright [yyyy] [name of copyright owner] 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. 202 | -------------------------------------------------------------------------------- /LICENSE-MIT: -------------------------------------------------------------------------------- 1 | Copyright (c) 2016 `const-cstr` Crate Developers 2 | 3 | Permission is hereby granted, free of charge, to any 4 | person obtaining a copy of this software and associated 5 | documentation files (the "Software"), to deal in the 6 | Software without restriction, including without 7 | limitation the rights to use, copy, modify, merge, 8 | publish, distribute, sublicense, and/or sell copies of 9 | the Software, and to permit persons to whom the Software 10 | is furnished to do so, subject to the following 11 | conditions: 12 | 13 | The above copyright notice and this permission notice 14 | shall be included in all copies or substantial portions 15 | of the Software. 16 | 17 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF 18 | ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED 19 | TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A 20 | PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT 21 | SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 22 | CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 23 | OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR 24 | IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 25 | DEALINGS IN THE SOFTWARE. 26 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # `const-cstr` [![](https://img.shields.io/crates/v/const-cstr.svg)](https://crates.io/crates/const-cstr) 2 | Create static C-compatible strings from Rust string literals. 3 | 4 | Usage 5 | ------ 6 | Cargo.toml: 7 | ```toml 8 | [dependencies] 9 | const-cstr = "0.1" 10 | ``` 11 | 12 | Crate root: 13 | ```rust 14 | #[macro_use] extern crate const_cstr; 15 | ``` 16 | 17 | Example 18 | ------- 19 | ```rust 20 | #[macro_use] extern crate const_cstr; 21 | 22 | use std::os::raw::c_char; 23 | use std::ffi::CStr; 24 | 25 | const_cstr! { 26 | HELLO_CSTR = "Hello, world!"; 27 | 28 | // Multiple declarations can be made with one invocation. 29 | // GOODNIGHT_CSTR = "Goodnight, sun!"; 30 | 31 | // But only with the same visibility: 32 | // pub GOODNIGHT_CSTR = "Goodnight, sun!"; 33 | // ^~~ Error: expected identifier, found `pub` 34 | } 35 | 36 | // Imagine this is an `extern "C"` function linked from some other lib. 37 | unsafe fn print_c_string(cstr: *const c_char) { 38 | println!("{}", CStr::from_ptr(cstr).to_str().unwrap()); 39 | } 40 | 41 | fn main() { 42 | // When just passed a literal, returns an rvalue instead. 43 | let goodnight_cstr = const_cstr!("Goodnight, sun!"); 44 | 45 | unsafe { 46 | print_c_string(HELLO_CSTR.as_ptr()); 47 | print_c_string(goodnight_cstr.as_ptr()); 48 | } 49 | } 50 | ``` 51 | 52 | Prints: 53 | 54 | ```notest 55 | Hello, world! 56 | Goodnight, sun! 57 | ``` 58 | 59 | ## License 60 | 61 | Licensed under either of 62 | * Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0) 63 | * MIT license ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT) 64 | at your option. 65 | 66 | ### Contribution 67 | 68 | Unless you explicitly state otherwise, any contribution intentionally submitted 69 | for inclusion in the work by you shall be dual licensed as above, without any 70 | additional terms or conditions. 71 | -------------------------------------------------------------------------------- /src/lib.rs: -------------------------------------------------------------------------------- 1 | // Copyright (c) 2015 const-cstr developers 2 | // Licensed under the Apache License, Version 2.0 3 | // or the MIT 5 | // license , 6 | // at your option. All files in the project carrying such 7 | // notice may not be copied, modified, or distributed except 8 | // according to those terms. 9 | //! Create static C-compatible strings from Rust string literals. 10 | //! 11 | //! Example 12 | //! ------- 13 | //! 14 | //! ```rust 15 | //! #[macro_use] extern crate const_cstr; 16 | //! 17 | //! use std::os::raw::c_char; 18 | //! use std::ffi::CStr; 19 | //! 20 | //! const_cstr! { 21 | //! HELLO_CSTR = "Hello, world!"; 22 | //! 23 | //! // Multiple declarations can be made with one invocation. 24 | //! // GOODNIGHT_CSTR = "Goodnight, sun!"; 25 | //! 26 | //! // But only with the same visibility: 27 | //! // pub GOODNIGHT_CSTR = "Goodnight, sun!"; 28 | //! // ^~~ Error: expected identifier, found `pub` 29 | //! } 30 | //! 31 | //! // Imagine this is an `extern "C"` function linked from some other lib. 32 | //! unsafe fn print_c_string(cstr: *const c_char) { 33 | //! println!("{}", CStr::from_ptr(cstr).to_str().unwrap()); 34 | //! } 35 | //! 36 | //! fn main() { 37 | //! // When just passed a literal, returns an rvalue instead. 38 | //! let goodnight_cstr = const_cstr!("Goodnight, sun!"); 39 | //! 40 | //! unsafe { 41 | //! print_c_string(HELLO_CSTR.as_ptr()); 42 | //! print_c_string(goodnight_cstr.as_ptr()); 43 | //! } 44 | //! } 45 | //! ``` 46 | //! 47 | //! Prints: 48 | //! 49 | //! ```notest 50 | //! Hello, world! 51 | //! Goodnight, sun! 52 | //! ``` 53 | 54 | use std::os::raw::c_char; 55 | use std::ffi::CStr; 56 | 57 | /// A type representing a static C-compatible string, wrapping `&'static str`. 58 | /// 59 | /// Note 60 | /// ---- 61 | /// Prefer the `const_cstr!` macro to create an instance of this struct 62 | /// over manual initialization. The macro will include the NUL byte for you. 63 | #[derive(Copy, Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Hash)] 64 | pub struct ConstCStr { 65 | /// The wrapped string value. Not intended to be used for manual initialization. 66 | /// Public only to allow initialization by the `const_cstr!` macro. 67 | /// 68 | /// Includes the NUL terminating byte. Use `to_str()` to get an `&'static str` 69 | /// without the NUL terminating byte. 70 | pub val: &'static str, 71 | } 72 | 73 | impl ConstCStr { 74 | /// Returns the wrapped string, without the NUL terminating byte. 75 | /// 76 | /// Compare to `CStr::to_str()` which checks that the string is valid UTF-8 first, 77 | /// since it starts from an arbitrary pointer instead of a Rust string slice. 78 | pub fn to_str(&self) -> &'static str { 79 | &self.val[..self.val.len() - 1] 80 | } 81 | 82 | /// Returns the wrapped string as a byte slice, **without** the NUL terminating byte. 83 | pub fn to_bytes(&self) -> &'static [u8] { 84 | self.to_str().as_bytes() 85 | } 86 | 87 | /// Returns the wrapped string as a byte slice, *with** the NUL terminating byte. 88 | pub fn to_bytes_with_nul(&self) -> &'static [u8] { 89 | self.val.as_bytes() 90 | } 91 | 92 | /// Returns a pointer to the beginning of the wrapped string. 93 | /// 94 | /// Suitable for passing to any function that expects a C-compatible string. 95 | /// Since the underlying string is guaranteed to be `'static`, 96 | /// the pointer should always be valid. 97 | /// 98 | /// Panics 99 | /// ------ 100 | /// If the wrapped string is not NUL-terminated. 101 | /// (Unlikely if you used the `const_cstr!` macro. This is just a sanity check.) 102 | pub fn as_ptr(&self) -> *const c_char { 103 | let bytes = self.val.as_bytes(); 104 | 105 | assert_eq!(bytes[bytes.len() - 1], b'\0'); 106 | 107 | self.val.as_bytes().as_ptr() as *const c_char 108 | } 109 | 110 | /// Returns the wrapped string as an `&'static CStr`, skipping the length check that 111 | /// `CStr::from_ptr()` performs (since we know the length already). 112 | /// 113 | /// Panics 114 | /// ------ 115 | /// If the wrapped string is not NUL-terminated. 116 | /// (Unlikely if you used the `const_cstr!` macro. This is just a sanity check.) 117 | pub fn as_cstr(&self) -> &'static CStr { 118 | let bytes = self.val.as_bytes(); 119 | 120 | assert_eq!(bytes[bytes.len() - 1], b'\0'); 121 | 122 | // This check is safe because of the above assert. 123 | // Interior nuls are more of a logic error than a memory saftey issue. 124 | unsafe { 125 | CStr::from_bytes_with_nul_unchecked(bytes) 126 | } 127 | } 128 | } 129 | 130 | /// Create a C-compatible string as an rvalue or a `const` binding. 131 | /// Appends a NUL byte to the passed string. 132 | /// 133 | /// Multiple `const` declarations can be created with one invocation, but only with the same 134 | /// visibility (`pub` or not). 135 | /// 136 | /// See crate root documentation for example usage. 137 | /// 138 | /// Note 139 | /// ---- 140 | /// For logical consistency, the passed string(s) should not contain any NUL bytes. 141 | /// Remember that functions consuming a C-string will only see up to the first NUL byte. 142 | #[macro_export] 143 | macro_rules! const_cstr { 144 | ($(pub $strname:ident = $strval:expr);+;) => ( 145 | $( 146 | pub const $strname: $crate::ConstCStr = const_cstr!($strval); 147 | )+ 148 | ); 149 | ($strval:expr) => ( 150 | $crate::ConstCStr { val: concat!($strval, "\0") } 151 | ); 152 | ($($strname:ident = $strval:expr);+;) => ( 153 | $( 154 | const $strname: $crate::ConstCStr = const_cstr!($strval); 155 | )+ 156 | ); 157 | } 158 | 159 | #[test] 160 | fn test_creates_valid_str() { 161 | const_cstr! { 162 | HELLO_CSTR = "Hello, world!"; 163 | } 164 | 165 | let cstr = unsafe { CStr::from_ptr(HELLO_CSTR.as_ptr()) }; 166 | 167 | assert_eq!(HELLO_CSTR.to_str(), cstr.to_str().unwrap()); 168 | } 169 | 170 | #[cfg(test)] 171 | mod test_creates_pub_str_mod { 172 | const_cstr! { 173 | pub FIRST = "first"; 174 | pub SECOND = "second"; 175 | } 176 | } 177 | 178 | #[test] 179 | fn test_creates_pub_str() { 180 | assert_eq!(test_creates_pub_str_mod::FIRST.to_str(), "first"); 181 | assert_eq!(test_creates_pub_str_mod::SECOND.to_str(), "second"); 182 | } 183 | --------------------------------------------------------------------------------