1 use std::ffi::{CStr, CString, NulError, FromBytesWithNulError};
2 use std::borrow::Cow;
3 use std::os::raw;
4
5 #[derive(Debug)]
6 pub struct NullError;
7
8 impl From<NulError> for NullError {
from(_: NulError) -> NullError9 fn from(_: NulError) -> NullError {
10 NullError
11 }
12 }
13
14 impl From<FromBytesWithNulError> for NullError {
from(_: FromBytesWithNulError) -> NullError15 fn from(_: FromBytesWithNulError) -> NullError {
16 NullError
17 }
18 }
19
20 impl From<NullError> for ::std::io::Error {
from(e: NullError) -> ::std::io::Error21 fn from(e: NullError) -> ::std::io::Error {
22 ::std::io::Error::new(::std::io::ErrorKind::Other, format!("{}", e))
23 }
24 }
25
26 impl ::std::error::Error for NullError {
description(&self) -> &str27 fn description(&self) -> &str { "non-final null byte found" }
28 }
29
30 impl ::std::fmt::Display for NullError {
fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result31 fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
32 write!(f, "non-final null byte found")
33 }
34 }
35
36 /// Checks for last byte and avoids allocating if it is zero.
37 ///
38 /// Non-last null bytes still result in an error.
cstr_cow_from_bytes<'a>(slice: &'a [u8]) -> Result<Cow<'a, CStr>, NullError>39 pub fn cstr_cow_from_bytes<'a>(slice: &'a [u8]) -> Result<Cow<'a, CStr>, NullError> {
40 static ZERO: raw::c_char = 0;
41 Ok(match slice.last() {
42 // Slice out of 0 elements
43 None => unsafe { Cow::Borrowed(CStr::from_ptr(&ZERO)) },
44 // Slice with trailing 0
45 Some(&0) => Cow::Borrowed(try!(CStr::from_bytes_with_nul(slice))),
46 // Slice with no trailing 0
47 Some(_) => Cow::Owned(try!(CString::new(slice))),
48 })
49 }
50
51 #[inline]
ensure_compatible_types<T, E>()52 pub fn ensure_compatible_types<T, E>() {
53 #[cold]
54 #[inline(never)]
55 fn dopanic() {
56 panic!("value of requested type cannot be dynamically loaded");
57 }
58 if ::std::mem::size_of::<T>() != ::std::mem::size_of::<E>() {
59 dopanic()
60 }
61 }
62