1use std::borrow::Cow;
2use std::ffi::{CStr, CString};
3use std::os::raw;
4
5use crate::Error;
6
7/// Checks for the last byte and avoids allocating if it is zero.
8///
9/// Non-last null bytes still result in an error.
10pub(crate) fn cstr_cow_from_bytes(slice: &[u8]) -> Result<Cow<'_, CStr>, Error> {
11 static ZERO: raw::c_char = 0;
12 Ok(match slice.last() {
13 // Slice out of 0 elements
14 None => unsafe { Cow::Borrowed(CStr::from_ptr(&ZERO)) },
15 // Slice with trailing 0
16 Some(&0) => Cow::Borrowed(
17 CStr::from_bytes_with_nul(slice)
18 .map_err(|source: FromBytesWithNulError| Error::CreateCStringWithTrailing { source })?,
19 ),
20 // Slice with no trailing 0
21 Some(_) => {
22 Cow::Owned(CString::new(slice).map_err(|source: NulError| Error::CreateCString { source })?)
23 }
24 })
25}
26
27#[inline]
28pub(crate) fn ensure_compatible_types<T, E>() -> Result<(), Error> {
29 if ::std::mem::size_of::<T>() != ::std::mem::size_of::<E>() {
30 Err(Error::IncompatibleSize)
31 } else {
32 Ok(())
33 }
34}
35