1 files changed, 56 insertions, 0 deletions
diff --git a/third_party/rust/cstr/src/lib.rs b/third_party/rust/cstr/src/lib.rs
new file mode 100644
index 0000000000..c9e69d924c
--- /dev/null
+++ b/third_party/rust/cstr/src/lib.rs
@@ -0,0 +1,56 @@
+//! A macro for getting `&'static CStr` from literal or identifier.
+//!
+//! This macro checks whether the given literal is valid for `CStr`
+//! at compile time, and returns a static reference of `CStr`.
+//!
+//! This macro can be used to to initialize constants on Rust 1.64 and above.
+//!
+//! ## Example
+//!
+//! ```
+//! use cstr::cstr;
+//! use std::ffi::CStr;
+//!
+//! let test = cstr!(b"hello\xff");
+//! assert_eq!(test, CStr::from_bytes_with_nul(b"hello\xff\0").unwrap());
+//! let test = cstr!("hello");
+//! assert_eq!(test, CStr::from_bytes_with_nul(b"hello\0").unwrap());
+//! let test = cstr!(hello);
+//! assert_eq!(test, CStr::from_bytes_with_nul(b"hello\0").unwrap());
+//! ```
+
+// While this isn't necessary when using Cargo >= 1.42, omitting it actually requires path-less
+// `--extern proc_macro` to be passed to `rustc` when building this crate. Some tools may not do
+// this correctly. So it's added as a precaution.
+extern crate proc_macro;
+
+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 { ::core::ffi::CStr::from_bytes_with_nul_unchecked(#s) }),
+        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")),
+    }
+}