std/sys/pal/common/
small_c_string.rsuse crate::ffi::{CStr, CString};
use crate::mem::MaybeUninit;
use crate::path::Path;
use crate::{io, ptr, slice};
#[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_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> {
    if bytes.len() >= MAX_STACK_ALLOCATION {
        run_with_cstr_allocating(bytes, f)
    } else {
        unsafe { run_with_cstr_stack(bytes, f) }
    }
}
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),
    }
}