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Diffstat (limited to 'vendor/rustix/src/path/dec_int.rs')
-rw-r--r-- | vendor/rustix/src/path/dec_int.rs | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/vendor/rustix/src/path/dec_int.rs b/vendor/rustix/src/path/dec_int.rs new file mode 100644 index 0000000..e9c46f4 --- /dev/null +++ b/vendor/rustix/src/path/dec_int.rs @@ -0,0 +1,120 @@ +//! Efficient decimal integer formatting. +//! +//! # Safety +//! +//! This uses `CStr::from_bytes_with_nul_unchecked` and +//! `str::from_utf8_unchecked`on the buffer that it filled itself. +#![allow(unsafe_code)] + +use crate::backend::fd::{AsFd, AsRawFd}; +use crate::ffi::CStr; +use core::fmt::Write; +use itoa::{Buffer, Integer}; +#[cfg(all(feature = "std", unix))] +use std::os::unix::ffi::OsStrExt; +#[cfg(all(feature = "std", target_os = "wasi"))] +use std::os::wasi::ffi::OsStrExt; +#[cfg(feature = "std")] +use {core::fmt, std::ffi::OsStr, std::path::Path}; + +/// Format an integer into a decimal `Path` component, without constructing a +/// temporary `PathBuf` or `String`. +/// +/// This is used for opening paths such as `/proc/self/fd/<fd>` on Linux. +/// +/// # Examples +/// +/// ``` +/// # #[cfg(any(feature = "fs", feature = "net"))] +/// use rustix::path::DecInt; +/// +/// # #[cfg(any(feature = "fs", feature = "net"))] +/// assert_eq!( +/// format!("hello {}", DecInt::new(9876).as_ref().display()), +/// "hello 9876" +/// ); +/// ``` +#[derive(Clone)] +pub struct DecInt { + // 20 `u8`s is enough to hold the decimal ASCII representation of any + // `u64`, and we add one for a NUL terminator for `as_c_str`. + buf: [u8; 20 + 1], + len: usize, +} + +impl DecInt { + /// Construct a new path component from an integer. + #[inline] + pub fn new<Int: Integer>(i: Int) -> Self { + let mut me = DecIntWriter(Self { + buf: [0; 20 + 1], + len: 0, + }); + let mut buf = Buffer::new(); + me.write_str(buf.format(i)).unwrap(); + me.0 + } + + /// Construct a new path component from a file descriptor. + #[inline] + pub fn from_fd<Fd: AsFd>(fd: Fd) -> Self { + Self::new(fd.as_fd().as_raw_fd()) + } + + /// Return the raw byte buffer as a `&str`. + #[inline] + pub fn as_str(&self) -> &str { + // SAFETY: `DecInt` always holds a formatted decimal number, so it's + // always valid UTF-8. + unsafe { core::str::from_utf8_unchecked(self.as_bytes()) } + } + + /// Return the raw byte buffer as a `&CStr`. + #[inline] + pub fn as_c_str(&self) -> &CStr { + let bytes_with_nul = &self.buf[..=self.len]; + debug_assert!(CStr::from_bytes_with_nul(bytes_with_nul).is_ok()); + + // SAFETY: `self.buf` holds a single decimal ASCII representation and + // at least one extra NUL byte. + unsafe { CStr::from_bytes_with_nul_unchecked(bytes_with_nul) } + } + + /// Return the raw byte buffer. + #[inline] + pub fn as_bytes(&self) -> &[u8] { + &self.buf[..self.len] + } +} + +struct DecIntWriter(DecInt); + +impl core::fmt::Write for DecIntWriter { + #[inline] + fn write_str(&mut self, s: &str) -> core::fmt::Result { + match self.0.buf.get_mut(self.0.len..self.0.len + s.len()) { + Some(slice) => { + slice.copy_from_slice(s.as_bytes()); + self.0.len += s.len(); + Ok(()) + } + None => Err(core::fmt::Error), + } + } +} + +#[cfg(feature = "std")] +impl AsRef<Path> for DecInt { + #[inline] + fn as_ref(&self) -> &Path { + let as_os_str: &OsStr = OsStrExt::from_bytes(&self.buf[..self.len]); + Path::new(as_os_str) + } +} + +#[cfg(feature = "std")] +impl fmt::Debug for DecInt { + fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { + self.as_str().fmt(fmt) + } +} |