libs: Move cstr!() into its own crate
Make the macro host_supported, for unittests.
This overshadows the homonymous crate from crates.io [1] but importing
and depending on an external crate for <10 lines of code seems overkill.
[1]: https://crates.io/crates/cstr
Bug: 308694211
Test: atest libcstr.tests
Test: m libcstr
Test: m pvmfw_bin rialto_bin vmbase_example_bin
Change-Id: If1bf37034fc004a380b3ba528b9d76393a865d3e
diff --git a/libs/cstr/src/lib.rs b/libs/cstr/src/lib.rs
new file mode 100644
index 0000000..ddf20fc
--- /dev/null
+++ b/libs/cstr/src/lib.rs
@@ -0,0 +1,50 @@
+// Copyright 2023, The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+//! Provide a safe const-compatible no_std macro for readable &'static CStr.
+
+#![no_std]
+
+/// Create &CStr out of &str literal
+#[macro_export]
+macro_rules! cstr {
+ ($str:literal) => {{
+ const S: &str = concat!($str, "\0");
+ const C: &::core::ffi::CStr = match ::core::ffi::CStr::from_bytes_with_nul(S.as_bytes()) {
+ Ok(v) => v,
+ Err(_) => panic!("string contains interior NUL"),
+ };
+ C
+ }};
+}
+
+#[cfg(test)]
+mod tests {
+ use super::*;
+ use std::ffi::CString;
+
+ #[test]
+ fn valid_input_string() {
+ let expected = CString::new("aaa").unwrap();
+ assert_eq!(cstr!("aaa"), expected.as_c_str());
+ }
+
+ #[test]
+ fn valid_empty_string() {
+ let expected = CString::new("").unwrap();
+ assert_eq!(cstr!(""), expected.as_c_str());
+ }
+
+ // As cstr!() panics at compile time, tests covering invalid inputs fail to compile!
+}