1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
use crate::parse::parse_input;
use proc_macro::TokenStream as RawTokenStream;
use proc_macro2::{Literal, Span, TokenStream};
use quote::{quote, quote_spanned};
use std::ffi::CString;
mod parse;
struct Error(Span, &'static str);
#[proc_macro]
pub fn cstr(input: RawTokenStream) -> RawTokenStream {
let tokens = match build_byte_str(input.into()) {
Ok(s) => quote!(unsafe {
#[allow(clippy::transmute_ptr_to_ref)]
::std::mem::transmute::<_, &::std::ffi::CStr>(
#s as *const [u8] as *const ::std::ffi::CStr
)
}),
Err(Error(span, msg)) => quote_spanned!(span => compile_error!(#msg)),
};
tokens.into()
}
fn build_byte_str(input: TokenStream) -> Result<Literal, Error> {
let (bytes, span) = parse_input(input)?;
match CString::new(bytes) {
Ok(s) => {
let mut lit = Literal::byte_string(s.as_bytes_with_nul());
lit.set_span(span);
Ok(lit)
}
Err(_) => Err(Error(span, "nul byte found in the literal")),
}
}