mirror of
https://github.com/topjohnwu/Magisk.git
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Add more to the Utf8CStr family
Better C strings with path operations
This commit is contained in:
topjohnwu
575
native/src/base/cstr.rs
Normal file
575
native/src/base/cstr.rs
Normal file
@@ -0,0 +1,575 @@
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use std::cmp::min;
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use std::ffi::{CStr, FromBytesWithNulError, OsStr};
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use std::fmt::{Arguments, Debug, Display, Formatter, Write};
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use std::ops::{Deref, DerefMut};
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use std::path::Path;
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use std::str::{Utf8Chunks, Utf8Error};
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use std::{fmt, mem, slice, str};
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use crate::slice_from_ptr_mut;
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use libc::c_char;
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use thiserror::Error;
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pub fn copy_cstr<T: AsRef<CStr> + ?Sized>(dest: &mut [u8], src: &T) -> usize {
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let src = src.as_ref().to_bytes_with_nul();
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let len = min(src.len(), dest.len());
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dest[..len].copy_from_slice(&src[..len]);
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len - 1
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}
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fn utf8_cstr_append(buf: &mut dyn Utf8CStrBuf, s: &[u8]) -> usize {
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let mut used = buf.len();
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if used >= buf.capacity() - 1 {
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// Truncate
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return 0;
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}
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let dest = unsafe { &mut buf.mut_buf()[used..] };
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let len = min(s.len(), dest.len() - 1);
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dest[..len].copy_from_slice(&s[..len]);
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dest[len] = b'\0';
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used += len;
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unsafe { buf.set_len(used) };
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len
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}
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fn utf8_cstr_append_lossy(buf: &mut dyn Utf8CStrBuf, s: &[u8]) -> usize {
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let chunks = Utf8Chunks::new(s);
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let mut len = 0_usize;
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for chunk in chunks {
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len += utf8_cstr_append(buf, chunk.valid().as_bytes());
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if !chunk.invalid().is_empty() {
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len += utf8_cstr_append(
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buf,
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char::REPLACEMENT_CHARACTER
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.encode_utf8(&mut [0; 4])
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.as_bytes(),
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);
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}
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}
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len
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}
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pub trait Utf8CStrBuf:
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Write + AsRef<Utf8CStr> + AsMut<Utf8CStr> + Deref<Target = Utf8CStr> + DerefMut
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{
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fn buf(&self) -> &[u8];
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fn len(&self) -> usize;
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// Modifying the underlying buffer or length is unsafe because it can either:
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// 1. Break null termination
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// 2. Break UTF-8 validation
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// 3. Introduce inner null byte in the string
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unsafe fn mut_buf(&mut self) -> &mut [u8];
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unsafe fn set_len(&mut self, len: usize);
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fn append(&mut self, s: &str) -> usize;
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fn append_lossy(&mut self, s: &[u8]) -> usize;
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unsafe fn append_unchecked(&mut self, s: &[u8]) -> usize;
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#[inline(always)]
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fn is_empty(&self) -> bool {
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self.len() == 0
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}
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#[inline(always)]
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fn capacity(&self) -> usize {
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self.buf().len()
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}
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fn clear(&mut self) {
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unsafe {
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self.mut_buf()[0] = b'\0';
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self.set_len(0);
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}
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}
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}
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trait Utf8CStrBufImpl: Utf8CStrBuf {
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#[inline(always)]
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fn as_utf8_cstr(&self) -> &Utf8CStr {
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// SAFETY: the internal buffer is always UTF-8 checked
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// SAFETY: self.used is guaranteed to always <= SIZE - 1
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unsafe { Utf8CStr::from_bytes_unchecked(self.buf().get_unchecked(..(self.len() + 1))) }
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}
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#[inline(always)]
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fn as_utf8_cstr_mut(&mut self) -> &mut Utf8CStr {
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// SAFETY: the internal buffer is always UTF-8 checked
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// SAFETY: self.used is guaranteed to always <= SIZE - 1
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unsafe {
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let len = self.len() + 1;
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Utf8CStr::from_bytes_unchecked_mut(self.mut_buf().get_unchecked_mut(..len))
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}
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}
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}
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// UTF-8 validated + null terminated reference to buffer
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pub struct Utf8CStrSlice<'a> {
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used: usize,
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buf: &'a mut [u8],
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}
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impl<'a> Utf8CStrSlice<'a> {
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pub unsafe fn from_ptr(buf: *mut u8, len: usize) -> Utf8CStrSlice<'a> {
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Self::from(slice_from_ptr_mut(buf, len))
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}
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}
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impl<'a> From<&'a mut [u8]> for Utf8CStrSlice<'a> {
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fn from(buf: &'a mut [u8]) -> Utf8CStrSlice<'a> {
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buf[0] = b'\0';
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Utf8CStrSlice { used: 0, buf }
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}
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}
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impl Utf8CStrBuf for Utf8CStrSlice<'_> {
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#[inline(always)]
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fn buf(&self) -> &[u8] {
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self.buf
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}
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#[inline(always)]
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fn len(&self) -> usize {
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self.used
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}
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#[inline(always)]
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unsafe fn mut_buf(&mut self) -> &mut [u8] {
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self.buf
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}
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#[inline(always)]
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unsafe fn set_len(&mut self, len: usize) {
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self.used = len;
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}
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#[inline(always)]
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fn append(&mut self, s: &str) -> usize {
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utf8_cstr_append(self, s.as_bytes())
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}
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#[inline(always)]
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fn append_lossy(&mut self, s: &[u8]) -> usize {
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utf8_cstr_append_lossy(self, s)
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}
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#[inline(always)]
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unsafe fn append_unchecked(&mut self, s: &[u8]) -> usize {
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utf8_cstr_append(self, s)
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}
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}
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// UTF-8 validated + null terminated buffer on the stack
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pub struct Utf8CStrArr<const N: usize> {
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used: usize,
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buf: [u8; N],
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}
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impl<const N: usize> Utf8CStrArr<N> {
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pub fn new() -> Self {
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Utf8CStrArr {
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used: 0,
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buf: [0; N],
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}
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}
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}
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impl<const N: usize> Utf8CStrBuf for Utf8CStrArr<N> {
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#[inline(always)]
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fn buf(&self) -> &[u8] {
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&self.buf
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}
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#[inline(always)]
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fn len(&self) -> usize {
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self.used
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}
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#[inline(always)]
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unsafe fn mut_buf(&mut self) -> &mut [u8] {
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&mut self.buf
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}
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#[inline(always)]
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unsafe fn set_len(&mut self, len: usize) {
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self.used = len;
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}
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#[inline(always)]
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fn append(&mut self, s: &str) -> usize {
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utf8_cstr_append(self, s.as_bytes())
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}
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#[inline(always)]
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fn append_lossy(&mut self, s: &[u8]) -> usize {
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utf8_cstr_append_lossy(self, s)
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}
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#[inline(always)]
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unsafe fn append_unchecked(&mut self, s: &[u8]) -> usize {
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utf8_cstr_append(self, s)
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}
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#[inline(always)]
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fn capacity(&self) -> usize {
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N
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}
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}
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impl Default for Utf8CStrArr<4096> {
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fn default() -> Self {
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Utf8CStrArr::<4096>::new()
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}
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}
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#[derive(Debug, Error)]
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pub enum StrErr {
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#[error(transparent)]
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Utf8Error(#[from] Utf8Error),
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#[error(transparent)]
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CStrError(#[from] FromBytesWithNulError),
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#[error("argument is null")]
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NullPointerError,
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}
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// Provide a way to have a heap allocated, UTF-8 validated, and null terminated string
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pub trait StringExt {
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fn nul_terminate(&mut self) -> &mut [u8];
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}
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impl StringExt for String {
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fn nul_terminate(&mut self) -> &mut [u8] {
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self.reserve(1);
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// SAFETY: the string is reserved to have enough capacity to fit in the null byte
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// SAFETY: the null byte is explicitly added outside of the string's length
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unsafe {
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let buf = slice::from_raw_parts_mut(self.as_mut_ptr(), self.len() + 1);
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*buf.get_unchecked_mut(self.len()) = b'\0';
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buf
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}
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}
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}
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// UTF-8 validated + null terminated string slice
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pub struct Utf8CStr([u8]);
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impl Utf8CStr {
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pub fn from_cstr(cstr: &CStr) -> Result<&Utf8CStr, StrErr> {
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// Validate the buffer during construction
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str::from_utf8(cstr.to_bytes())?;
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Ok(unsafe { Self::from_bytes_unchecked(cstr.to_bytes_with_nul()) })
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}
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pub fn from_bytes(buf: &[u8]) -> Result<&Utf8CStr, StrErr> {
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Self::from_cstr(CStr::from_bytes_with_nul(buf)?)
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}
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pub fn from_bytes_mut(buf: &mut [u8]) -> Result<&mut Utf8CStr, StrErr> {
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CStr::from_bytes_with_nul(buf)?;
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str::from_utf8(buf)?;
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// Both condition checked
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unsafe { Ok(mem::transmute(buf)) }
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}
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pub fn from_string(s: &mut String) -> &mut Utf8CStr {
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let buf = s.nul_terminate();
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// SAFETY: the null byte is explicitly added to the buffer
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unsafe { mem::transmute(buf) }
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}
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#[inline(always)]
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pub unsafe fn from_bytes_unchecked(buf: &[u8]) -> &Utf8CStr {
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mem::transmute(buf)
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}
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#[inline(always)]
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pub unsafe fn from_bytes_unchecked_mut(buf: &mut [u8]) -> &mut Utf8CStr {
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mem::transmute(buf)
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}
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pub unsafe fn from_ptr<'a>(ptr: *const c_char) -> Result<&'a Utf8CStr, StrErr> {
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if ptr.is_null() {
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return Err(StrErr::NullPointerError);
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}
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Self::from_cstr(unsafe { CStr::from_ptr(ptr) })
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}
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#[inline(always)]
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pub fn as_bytes_with_nul(&self) -> &[u8] {
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&self.0
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}
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#[inline(always)]
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pub fn as_ptr(&self) -> *const c_char {
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self.0.as_ptr().cast()
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}
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#[inline(always)]
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pub fn as_mut_ptr(&mut self) -> *mut c_char {
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self.0.as_mut_ptr().cast()
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}
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#[inline(always)]
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pub fn as_cstr(&self) -> &CStr {
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// SAFETY: Already validated as null terminated during construction
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unsafe { CStr::from_bytes_with_nul_unchecked(&self.0) }
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}
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#[inline(always)]
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pub fn as_str(&self) -> &str {
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// SAFETY: Already UTF-8 validated during construction
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// SAFETY: The length of the slice is at least 1 due to null termination check
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unsafe { str::from_utf8_unchecked(self.0.get_unchecked(..self.0.len() - 1)) }
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}
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#[inline(always)]
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pub fn as_str_mut(&mut self) -> &mut str {
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// SAFETY: Already UTF-8 validated during construction
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// SAFETY: The length of the slice is at least 1 due to null termination check
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unsafe { str::from_utf8_unchecked_mut(self.0.get_unchecked_mut(..self.0.len() - 1)) }
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}
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}
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impl Deref for Utf8CStr {
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type Target = str;
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#[inline(always)]
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fn deref(&self) -> &str {
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self.as_str()
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}
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}
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impl DerefMut for Utf8CStr {
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#[inline(always)]
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fn deref_mut(&mut self) -> &mut Self::Target {
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self.as_str_mut()
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}
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}
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// File system path extensions types
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pub struct FsPath(Utf8CStr);
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impl FsPath {
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#[inline(always)]
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pub fn from<'a, T: AsRef<Utf8CStr>>(value: T) -> &'a FsPath {
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unsafe { mem::transmute(value.as_ref()) }
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}
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#[inline(always)]
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pub fn from_mut<'a, T: AsMut<Utf8CStr>>(mut value: T) -> &'a mut FsPath {
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unsafe { mem::transmute(value.as_mut()) }
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}
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}
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impl Deref for FsPath {
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type Target = Utf8CStr;
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#[inline(always)]
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fn deref(&self) -> &Utf8CStr {
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&self.0
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}
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}
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impl DerefMut for FsPath {
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#[inline(always)]
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fn deref_mut(&mut self) -> &mut Utf8CStr {
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&mut self.0
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}
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}
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pub struct FsPathBuf<'a>(&'a mut dyn Utf8CStrBuf);
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impl<'a> FsPathBuf<'a> {
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pub fn new(value: &'a mut dyn Utf8CStrBuf) -> Self {
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FsPathBuf(value)
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}
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pub fn join<T: AsRef<str>>(self, path: T) -> Self {
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fn inner(buf: &mut dyn Utf8CStrBuf, path: &str) {
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if path.starts_with('/') {
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buf.clear();
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} else {
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buf.append("/");
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}
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buf.append(path);
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}
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inner(self.0, path.as_ref());
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self
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}
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pub fn join_fmt<T: Display>(self, name: T) -> Self {
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fn inner(buf: &mut dyn Utf8CStrBuf, path: Arguments) {
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buf.write_fmt(path).ok();
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}
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inner(self.0, format_args!("/{}", name));
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self
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}
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}
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impl<'a> Deref for FsPathBuf<'a> {
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type Target = FsPath;
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fn deref(&self) -> &FsPath {
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FsPath::from(&self.0)
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}
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}
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impl<'a> DerefMut for FsPathBuf<'a> {
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fn deref_mut(&mut self) -> &mut Self::Target {
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FsPath::from_mut(&mut self.0)
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}
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}
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// Boilerplate trait implementations
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macro_rules! impl_str {
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($( ($t:ty, $($g:tt)*) )*) => {$(
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impl<$($g)*> AsRef<Utf8CStr> for $t {
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#[inline(always)]
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||||
fn as_ref(&self) -> &Utf8CStr {
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||||
self
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||||
}
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||||
}
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||||
impl<$($g)*> AsRef<str> for $t {
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||||
#[inline(always)]
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||||
fn as_ref(&self) -> &str {
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self.as_str()
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||||
}
|
||||
}
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impl<$($g)*> AsRef<CStr> for $t {
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||||
#[inline(always)]
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fn as_ref(&self) -> &CStr {
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||||
self.as_cstr()
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||||
}
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||||
}
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impl<$($g)*> AsRef<OsStr> for $t {
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||||
#[inline(always)]
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||||
fn as_ref(&self) -> &OsStr {
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||||
OsStr::new(self.as_str())
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||||
}
|
||||
}
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||||
impl<$($g)*> AsRef<Path> for $t {
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||||
#[inline(always)]
|
||||
fn as_ref(&self) -> &Path {
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||||
Path::new(self.as_str())
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||||
}
|
||||
}
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||||
impl<$($g)*> Display for $t {
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||||
#[inline(always)]
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||||
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
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||||
Display::fmt(self.as_str(), f)
|
||||
}
|
||||
}
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impl<$($g)*> Debug for $t {
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||||
#[inline(always)]
|
||||
fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
|
||||
Debug::fmt(self.as_str(), f)
|
||||
}
|
||||
}
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impl<$($g)*> PartialEq<str> for $t {
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||||
#[inline(always)]
|
||||
fn eq(&self, other: &str) -> bool {
|
||||
self.as_str() == other
|
||||
}
|
||||
}
|
||||
impl<$($g)*> PartialEq<$t> for str {
|
||||
#[inline(always)]
|
||||
fn eq(&self, other: &$t) -> bool {
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||||
self == other.as_str()
|
||||
}
|
||||
}
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||||
impl<$($g)*> PartialEq<CStr> for $t {
|
||||
#[inline(always)]
|
||||
fn eq(&self, other: &CStr) -> bool {
|
||||
self.as_cstr() == other
|
||||
}
|
||||
}
|
||||
impl<$($g)*> PartialEq<$t> for CStr {
|
||||
#[inline(always)]
|
||||
fn eq(&self, other: &$t) -> bool {
|
||||
self == other.as_cstr()
|
||||
}
|
||||
}
|
||||
impl<T: AsRef<Utf8CStr>, $($g)*> PartialEq<T> for $t {
|
||||
#[inline(always)]
|
||||
fn eq(&self, other: &T) -> bool {
|
||||
self.as_bytes_with_nul() == other.as_ref().as_bytes_with_nul()
|
||||
}
|
||||
}
|
||||
)*}
|
||||
}
|
||||
|
||||
impl_str!(
|
||||
(Utf8CStr,)
|
||||
(FsPath,)
|
||||
(FsPathBuf<'_>,)
|
||||
);
|
||||
|
||||
macro_rules! impl_str_buf {
|
||||
($( ($t:ty, $($g:tt)*) )*) => {$(
|
||||
impl_str!(($t, $($g)*));
|
||||
impl<$($g)*> $t {
|
||||
#[inline(always)]
|
||||
pub fn append<T: AsRef<str>>(&mut self, s: T) -> usize {
|
||||
utf8_cstr_append(self, s.as_ref().as_bytes())
|
||||
}
|
||||
}
|
||||
impl<$($g)*> Utf8CStrBufImpl for $t {}
|
||||
impl<$($g)*> Write for $t {
|
||||
#[inline(always)]
|
||||
fn write_str(&mut self, s: &str) -> fmt::Result {
|
||||
self.append(s);
|
||||
Ok(())
|
||||
}
|
||||
}
|
||||
impl<$($g)*> Deref for $t {
|
||||
type Target = Utf8CStr;
|
||||
|
||||
#[inline(always)]
|
||||
fn deref(&self) -> &Utf8CStr {
|
||||
self.as_utf8_cstr()
|
||||
}
|
||||
}
|
||||
impl<$($g)*> DerefMut for $t {
|
||||
#[inline(always)]
|
||||
fn deref_mut(&mut self) -> &mut Utf8CStr {
|
||||
self.as_utf8_cstr_mut()
|
||||
}
|
||||
}
|
||||
impl<$($g)*> AsMut<Utf8CStr> for $t {
|
||||
#[inline(always)]
|
||||
fn as_mut(&mut self) -> &mut Utf8CStr {
|
||||
self
|
||||
}
|
||||
}
|
||||
)*}
|
||||
}
|
||||
|
||||
impl_str_buf!(
|
||||
(Utf8CStrSlice<'_>,)
|
||||
(Utf8CStrArr<N>, const N: usize)
|
||||
);
|
||||
|
||||
// The cstr! macro is copied from https://github.com/bytecodealliance/rustix/blob/main/src/cstr.rs
|
||||
|
||||
#[macro_export]
|
||||
macro_rules! cstr {
|
||||
($($str:tt)*) => {{
|
||||
assert!(
|
||||
!($($str)*).bytes().any(|b| b == b'\0'),
|
||||
"cstr argument contains embedded NUL bytes",
|
||||
);
|
||||
#[allow(unused_unsafe)]
|
||||
unsafe {
|
||||
$crate::Utf8CStr::from_bytes_unchecked(concat!($($str)*, "\0").as_bytes())
|
||||
}
|
||||
}};
|
||||
}
|
||||
|
||||
#[macro_export]
|
||||
macro_rules! raw_cstr {
|
||||
($($str:tt)*) => {{
|
||||
cstr!($($str)*).as_ptr()
|
||||
}};
|
||||
}
|
||||
Reference in New Issue
Block a user