| 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>(path: &Path, f: &dyn Fn(&CStr) -> io::Result<T>) -> io::Result<T> { |
| run_with_cstr(path.as_os_str().as_encoded_bytes(), f) |
| } |
| |
| #[inline] |
| pub fn run_with_cstr<T>(bytes: &[u8], f: &dyn Fn(&CStr) -> io::Result<T>) -> io::Result<T> { |
| // Dispatch and dyn erase the closure type to prevent mono bloat. |
| // See https://github.com/rust-lang/rust/pull/121101. |
| if bytes.len() >= MAX_STACK_ALLOCATION { |
| run_with_cstr_allocating(bytes, f) |
| } else { |
| unsafe { run_with_cstr_stack(bytes, f) } |
| } |
| } |
| |
| /// # Safety |
| /// |
| /// `bytes` must have a length less than `MAX_STACK_ALLOCATION`. |
| unsafe fn run_with_cstr_stack<T>( |
| bytes: &[u8], |
| f: &dyn Fn(&CStr) -> io::Result<T>, |
| ) -> io::Result<T> { |
| 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>(bytes: &[u8], f: &dyn Fn(&CStr) -> io::Result<T>) -> io::Result<T> { |
| match CString::new(bytes) { |
| Ok(s) => f(&s), |
| Err(_) => Err(NUL_ERR), |
| } |
| } |