123 lines
3.2 KiB
Rust
123 lines
3.2 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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use std::ffi;
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use std::ops::Deref;
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use smallvec::SmallVec;
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const SIZE: usize = 36;
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/// Like SmallVec but for C strings.
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#[derive(Clone)]
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pub struct SmallCStr {
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data: SmallVec<[u8; SIZE]>,
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}
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impl SmallCStr {
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#[inline]
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pub fn new(s: &str) -> SmallCStr {
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let len = s.len();
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let len1 = len + 1;
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let data = if len < SIZE {
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let mut buf = [0; SIZE];
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buf[..len].copy_from_slice(s.as_bytes());
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SmallVec::from_buf_and_len(buf, len1)
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} else {
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let mut data = Vec::with_capacity(len1);
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data.extend_from_slice(s.as_bytes());
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data.push(0);
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SmallVec::from_vec(data)
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};
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if let Err(e) = ffi::CStr::from_bytes_with_nul(&data) {
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panic!("The string \"{}\" cannot be converted into a CStr: {}", s, e);
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}
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SmallCStr { data }
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}
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#[inline]
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pub fn new_with_nul(s: &str) -> SmallCStr {
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let b = s.as_bytes();
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if let Err(e) = ffi::CStr::from_bytes_with_nul(b) {
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panic!("The string \"{}\" cannot be converted into a CStr: {}", s, e);
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}
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SmallCStr { data: SmallVec::from_slice(s.as_bytes()) }
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}
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#[inline]
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pub fn as_c_str(&self) -> &ffi::CStr {
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unsafe {
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ffi::CStr::from_bytes_with_nul_unchecked(&self.data[..])
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}
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}
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#[inline]
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pub fn len_with_nul(&self) -> usize {
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self.data.len()
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}
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pub fn spilled(&self) -> bool {
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self.data.spilled()
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}
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}
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impl Deref for SmallCStr {
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type Target = ffi::CStr;
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fn deref(&self) -> &ffi::CStr {
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self.as_c_str()
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}
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}
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#[test]
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fn short() {
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const TEXT: &str = "abcd";
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let reference = ffi::CString::new(TEXT.to_string()).unwrap();
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let scs = SmallCStr::new(TEXT);
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assert_eq!(scs.len_with_nul(), TEXT.len() + 1);
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assert_eq!(scs.as_c_str(), reference.as_c_str());
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assert!(!scs.spilled());
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}
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#[test]
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fn empty() {
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const TEXT: &str = "";
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let reference = ffi::CString::new(TEXT.to_string()).unwrap();
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let scs = SmallCStr::new(TEXT);
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assert_eq!(scs.len_with_nul(), TEXT.len() + 1);
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assert_eq!(scs.as_c_str(), reference.as_c_str());
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assert!(!scs.spilled());
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}
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#[test]
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fn long() {
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const TEXT: &str = "01234567890123456789012345678901234567890123456789\
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01234567890123456789012345678901234567890123456789\
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01234567890123456789012345678901234567890123456789";
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let reference = ffi::CString::new(TEXT.to_string()).unwrap();
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let scs = SmallCStr::new(TEXT);
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assert_eq!(scs.len_with_nul(), TEXT.len() + 1);
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assert_eq!(scs.as_c_str(), reference.as_c_str());
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assert!(scs.spilled());
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}
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#[test]
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#[should_panic]
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fn internal_nul() {
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let _ = SmallCStr::new("abcd\0def");
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}
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