1 files changed, 36 insertions, 16 deletions

diff --git a/vendor/rustix/src/process/chdir.rs b/vendor/rustix/src/process/chdir.rs
index 4951e5670..0da0b5c2e 100644
--- a/vendor/rustix/src/process/chdir.rs
+++ b/vendor/rustix/src/process/chdir.rs
@@ -1,9 +1,13 @@
-use crate::ffi::CString;
-use crate::path::SMALL_PATH_BUFFER_SIZE;
-use crate::{backend, io, path};
-use alloc::vec::Vec;
 #[cfg(not(target_os = "fuchsia"))]
-use backend::fd::AsFd;
+use crate::backend::fd::AsFd;
+#[cfg(any(feature = "fs", not(target_os = "fuchsia")))]
+use crate::{backend, io};
+#[cfg(feature = "fs")]
+use {
+    crate::ffi::{CStr, CString},
+    crate::path::{self, SMALL_PATH_BUFFER_SIZE},
+    alloc::vec::Vec,
+};
 
 /// `chdir(path)`—Change the current working directory.
 ///
@@ -14,6 +18,8 @@ use backend::fd::AsFd;
 /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/chdir.html
 /// [Linux]: https://man7.org/linux/man-pages/man2/chdir.2.html
 #[inline]
+#[cfg(feature = "fs")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "fs")))]
 pub fn chdir<P: path::Arg>(path: P) -> io::Result<()> {
     path.into_with_c_str(backend::process::syscalls::chdir)
 }
@@ -32,9 +38,9 @@ pub fn fchdir<Fd: AsFd>(fd: Fd) -> io::Result<()> {
     backend::process::syscalls::fchdir(fd.as_fd())
 }
 
-/// `getcwd()`—Return the current working directory.
+/// `getCWD`—Return the current working directory.
 ///
-/// If `reuse` is non-empty, reuse its buffer to store the result if possible.
+/// If `reuse` already has available capacity, reuse it if possible.
 ///
 /// # References
 ///  - [POSIX]
@@ -42,29 +48,43 @@ pub fn fchdir<Fd: AsFd>(fd: Fd) -> io::Result<()> {
 ///
 /// [POSIX]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/getcwd.html
 /// [Linux]: https://man7.org/linux/man-pages/man3/getcwd.3.html
+#[cfg(feature = "fs")]
 #[cfg(not(target_os = "wasi"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "fs")))]
 #[inline]
 pub fn getcwd<B: Into<Vec<u8>>>(reuse: B) -> io::Result<CString> {
     _getcwd(reuse.into())
 }
 
+#[cfg(feature = "fs")]
+#[allow(unsafe_code)]
 fn _getcwd(mut buffer: Vec<u8>) -> io::Result<CString> {
-    // This code would benefit from having a better way to read into
-    // uninitialized memory, but that requires `unsafe`.
     buffer.clear();
     buffer.reserve(SMALL_PATH_BUFFER_SIZE);
-    buffer.resize(buffer.capacity(), 0_u8);
 
     loop {
-        match backend::process::syscalls::getcwd(&mut buffer) {
+        match backend::process::syscalls::getcwd(buffer.spare_capacity_mut()) {
             Err(io::Errno::RANGE) => {
-                buffer.reserve(1); // use `Vec` reallocation strategy to grow capacity exponentially
-                buffer.resize(buffer.capacity(), 0_u8);
+                buffer.reserve(buffer.capacity() + 1); // use `Vec` reallocation strategy to grow capacity exponentially
             }
             Ok(_) => {
-                let len = buffer.iter().position(|x| *x == b'\0').unwrap();
-                buffer.resize(len, 0_u8);
-                return Ok(CString::new(buffer).unwrap());
+                // SAFETY:
+                // - "These functions return a null-terminated string"
+                // - [POSIX definition 3.375: String]: "A contiguous sequence of bytes
+                //   terminated by and including the first null byte."
+                //
+                // Thus, there will be a single NUL byte at the end of the string.
+                //
+                // [POSIX definition 3.375: String]: https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_375
+                unsafe {
+                    buffer.set_len(
+                        CStr::from_ptr(buffer.as_ptr().cast())
+                            .to_bytes_with_nul()
+                            .len(),
+                    );
+
+                    return Ok(CString::from_vec_with_nul_unchecked(buffer));
+                }
             }
             Err(errno) => return Err(errno),
         }