mbedtls 0.13.6

Idiomatic Rust wrapper for MbedTLS, allowing you to use MbedTLS with only safe code while being able to use such great Rust features like error handling and closures. Building on MbedTLS's focus on embedded use, this crate can be used in a no_std environment.
Documentation 
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/// Returns the Cargo build-unit identifier from either supported build directory layout.
///
/// Cargo controls this layout independently of rustc's version, so inspect the path instead of
/// relying on the active toolchain version. The legacy layout is
/// `build/mbedtls-<hash>/out`; the new layout is `build/mbedtls/<hash>/out`.
///
/// Ref:
/// - https://github.com/rust-lang/cargo/issues/15010
/// - https://github.com/rust-lang/cargo/issues/17182
pub(crate) fn compilation_symbol_suffix(out_dir: &str) -> Option<&str> {
    let mut components = out_dir.rsplit(|c| c == '/' || c == '\\');
    if components.next()? != "out" {
        return None;
    }

    let build_unit = components.next()?;
    if let Some(suffix) = build_unit.strip_prefix("mbedtls-") {
        return (!suffix.is_empty()).then_some(suffix);
    }

    if !build_unit.is_empty() && components.next()? == "mbedtls" {
        return Some(build_unit);
    }

    None
}

#[cfg(test)]
mod tests {
    use super::compilation_symbol_suffix;

    #[test]
    fn extracts_suffix_from_supported_cargo_layouts() {
        let test_cases = [
            // Legacy Cargo layout on Unix.
            ("target/debug/build/mbedtls-3202cb041a903437/out", "3202cb041a903437"),
            // Cargo build directory layout v2 on Unix.
            ("target/debug/build/mbedtls/f8d961f56b5f3f44/out", "f8d961f56b5f3f44"),
            // Legacy Cargo layout on Windows.
            (r"target\debug\build\mbedtls-3202cb041a903437\out", "3202cb041a903437"),
            // Cargo build directory layout v2 on Windows.
            (r"target\debug\build\mbedtls\f8d961f56b5f3f44\out", "f8d961f56b5f3f44"),
        ];

        for (out_dir, suffix) in test_cases {
            assert_eq!(compilation_symbol_suffix(out_dir), Some(suffix));
        }
    }

    #[test]
    fn rejects_unsupported_or_malformed_cargo_layouts() {
        let test_cases = [
            "target/debug/build/mbedtls/hash/not-out",
            "target/debug/build/other-crate-3202cb041a903437/out",
            "target/debug/build/other-crate/f8d961f56b5f3f44/out",
            "target/debug/build/mbedtls/out",
            "target/debug/build/mbedtls-/out",
            "target/debug/build/mbedtls//out",
        ];

        for out_dir in test_cases {
            assert_eq!(compilation_symbol_suffix(out_dir), None);
        }
    }
}