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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:11:38 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:12:43 +0000 |
commit | cf94bdc0742c13e2a0cac864c478b8626b266e1b (patch) | |
tree | 044670aa50cc5e2b4229aa0b6b3df6676730c0a6 /library/std/src/sys/common/small_c_string.rs | |
parent | Adding debian version 1.65.0+dfsg1-2. (diff) | |
download | rustc-cf94bdc0742c13e2a0cac864c478b8626b266e1b.tar.xz rustc-cf94bdc0742c13e2a0cac864c478b8626b266e1b.zip |
Merging upstream version 1.66.0+dfsg1.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'library/std/src/sys/common/small_c_string.rs')
-rw-r--r-- | library/std/src/sys/common/small_c_string.rs | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/library/std/src/sys/common/small_c_string.rs b/library/std/src/sys/common/small_c_string.rs new file mode 100644 index 000000000..01acd5191 --- /dev/null +++ b/library/std/src/sys/common/small_c_string.rs @@ -0,0 +1,58 @@ +use crate::ffi::{CStr, CString}; +use crate::mem::MaybeUninit; +use crate::path::Path; +use crate::slice; +use crate::{io, ptr}; + +// Make sure to stay under 4096 so the compiler doesn't insert a probe frame: +// https://docs.rs/compiler_builtins/latest/compiler_builtins/probestack/index.html +#[cfg(not(target_os = "espidf"))] +const MAX_STACK_ALLOCATION: usize = 384; +#[cfg(target_os = "espidf")] +const MAX_STACK_ALLOCATION: usize = 32; + +const NUL_ERR: io::Error = + io::const_io_error!(io::ErrorKind::InvalidInput, "file name contained an unexpected NUL byte"); + +#[inline] +pub fn run_path_with_cstr<T, F>(path: &Path, f: F) -> io::Result<T> +where + F: FnOnce(&CStr) -> io::Result<T>, +{ + run_with_cstr(path.as_os_str().bytes(), f) +} + +#[inline] +pub fn run_with_cstr<T, F>(bytes: &[u8], f: F) -> io::Result<T> +where + F: FnOnce(&CStr) -> io::Result<T>, +{ + if bytes.len() >= MAX_STACK_ALLOCATION { + return run_with_cstr_allocating(bytes, f); + } + + let mut buf = MaybeUninit::<[u8; MAX_STACK_ALLOCATION]>::uninit(); + let buf_ptr = buf.as_mut_ptr() as *mut u8; + + unsafe { + ptr::copy_nonoverlapping(bytes.as_ptr(), buf_ptr, bytes.len()); + buf_ptr.add(bytes.len()).write(0); + } + + match CStr::from_bytes_with_nul(unsafe { slice::from_raw_parts(buf_ptr, bytes.len() + 1) }) { + Ok(s) => f(s), + Err(_) => Err(NUL_ERR), + } +} + +#[cold] +#[inline(never)] +fn run_with_cstr_allocating<T, F>(bytes: &[u8], f: F) -> io::Result<T> +where + F: FnOnce(&CStr) -> io::Result<T>, +{ + match CString::new(bytes) { + Ok(s) => f(&s), + Err(_) => Err(NUL_ERR), + } +} |