1 use crate::ffi::{CStr, CString};
2 use crate::mem::MaybeUninit;
3 use crate::path::Path;
4 use crate::slice;
5 use crate::{io, ptr};
6
7 // Make sure to stay under 4096 so the compiler doesn't insert a probe frame:
8 // https://docs.rs/compiler_builtins/latest/compiler_builtins/probestack/index.html
9 #[cfg(not(target_os = "espidf"))]
10 const MAX_STACK_ALLOCATION: usize = 384;
11 #[cfg(target_os = "espidf")]
12 const MAX_STACK_ALLOCATION: usize = 32;
13
14 const NUL_ERR: io::Error =
15 io::const_io_error!(io::ErrorKind::InvalidInput, "file name contained an unexpected NUL byte");
16
17 #[inline]
run_path_with_cstr<T, F>(path: &Path, f: F) -> io::Result<T> where F: FnOnce(&CStr) -> io::Result<T>,18 pub fn run_path_with_cstr<T, F>(path: &Path, f: F) -> io::Result<T>
19 where
20 F: FnOnce(&CStr) -> io::Result<T>,
21 {
22 run_with_cstr(path.as_os_str().as_os_str_bytes(), f)
23 }
24
25 #[inline]
run_with_cstr<T, F>(bytes: &[u8], f: F) -> io::Result<T> where F: FnOnce(&CStr) -> io::Result<T>,26 pub fn run_with_cstr<T, F>(bytes: &[u8], f: F) -> io::Result<T>
27 where
28 F: FnOnce(&CStr) -> io::Result<T>,
29 {
30 if bytes.len() >= MAX_STACK_ALLOCATION {
31 return run_with_cstr_allocating(bytes, f);
32 }
33
34 let mut buf = MaybeUninit::<[u8; MAX_STACK_ALLOCATION]>::uninit();
35 let buf_ptr = buf.as_mut_ptr() as *mut u8;
36
37 unsafe {
38 ptr::copy_nonoverlapping(bytes.as_ptr(), buf_ptr, bytes.len());
39 buf_ptr.add(bytes.len()).write(0);
40 }
41
42 match CStr::from_bytes_with_nul(unsafe { slice::from_raw_parts(buf_ptr, bytes.len() + 1) }) {
43 Ok(s) => f(s),
44 Err(_) => Err(NUL_ERR),
45 }
46 }
47
48 #[cold]
49 #[inline(never)]
run_with_cstr_allocating<T, F>(bytes: &[u8], f: F) -> io::Result<T> where F: FnOnce(&CStr) -> io::Result<T>,50 fn run_with_cstr_allocating<T, F>(bytes: &[u8], f: F) -> io::Result<T>
51 where
52 F: FnOnce(&CStr) -> io::Result<T>,
53 {
54 match CString::new(bytes) {
55 Ok(s) => f(&s),
56 Err(_) => Err(NUL_ERR),
57 }
58 }
59