Josh Megnauth
101 lines
3.0 KiB
Rust
101 lines
3.0 KiB
Rust
//! Nul-terminated byte strings.
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use core::{marker::PhantomData, ptr::NonNull, str::Utf8Error};
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use alloc::{
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borrow::{Cow, ToOwned},
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string::String,
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};
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use crate::{header::string::strlen, platform::types::c_char};
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/// C string wrapper, guaranteed to be
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#[derive(Clone, Copy)]
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#[repr(transparent)]
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pub struct CStr<'a> {
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ptr: NonNull<c_char>,
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_marker: PhantomData<&'a [u8]>,
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}
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impl<'a> CStr<'a> {
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/// Safety
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///
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/// The ptr must be valid up to and including the first NUL byte from the base ptr.
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pub const unsafe fn from_ptr(ptr: *const c_char) -> Self {
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Self {
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ptr: NonNull::new_unchecked(ptr as *mut c_char),
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_marker: PhantomData,
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}
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}
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pub unsafe fn from_nullable_ptr(ptr: *const c_char) -> Option<Self> {
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if ptr.is_null() {
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None
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} else {
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Some(Self::from_ptr(ptr))
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}
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}
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pub fn to_bytes_with_nul(self) -> &'a [u8] {
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unsafe {
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// SAFETY: The string must be valid at least until (and including) the NUL byte.
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let len = strlen(self.ptr.as_ptr());
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core::slice::from_raw_parts(self.ptr.as_ptr().cast(), len + 1)
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}
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}
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pub fn to_bytes(self) -> &'a [u8] {
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let s = self.to_bytes_with_nul();
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&s[..s.len() - 1]
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}
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pub fn to_str(self) -> Result<&'a str, Utf8Error> {
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core::str::from_utf8(self.to_bytes())
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}
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pub fn to_string_lossy(self) -> Cow<'a, str> {
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String::from_utf8_lossy(self.to_bytes())
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}
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pub const fn as_ptr(self) -> *const c_char {
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self.ptr.as_ptr()
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}
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pub const unsafe fn from_bytes_with_nul_unchecked(bytes: &'a [u8]) -> Self {
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Self::from_ptr(bytes.as_ptr().cast())
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}
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pub fn from_bytes_with_nul(bytes: &'a [u8]) -> Result<Self, FromBytesWithNulError> {
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if bytes.last() != Some(&b'\0') || bytes[..bytes.len() - 1].contains(&b'\0') {
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return Err(FromBytesWithNulError);
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}
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Ok(unsafe { Self::from_bytes_with_nul_unchecked(bytes) })
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}
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pub fn from_bytes_until_nul(bytes: &'a [u8]) -> Result<Self, FromBytesUntilNulError> {
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if !bytes.contains(&b'\0') {
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return Err(FromBytesUntilNulError);
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}
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Ok(unsafe { Self::from_bytes_with_nul_unchecked(bytes) })
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}
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pub fn to_owned_cstring(self) -> CString {
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CString::from(unsafe { core::ffi::CStr::from_ptr(self.ptr.as_ptr()) })
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}
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pub fn borrow(string: &'a CString) -> Self {
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unsafe { Self::from_ptr(string.as_ptr()) }
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}
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}
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unsafe impl Send for CStr<'_> {}
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unsafe impl Sync for CStr<'_> {}
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impl From<&core::ffi::CStr> for CStr<'_> {
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fn from(s: &core::ffi::CStr) -> Self {
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// SAFETY:
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// * We can assume that `s` is valid because the caller should have upheld its
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// safety concerns when constructing it.
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unsafe { Self::from_ptr(s.as_ptr()) }
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}
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}
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#[derive(Debug)]
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pub struct FromBytesWithNulError;
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#[derive(Debug)]
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pub struct FromBytesUntilNulError;
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pub use alloc::ffi::CString;
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