feat: fix LazyLock issue and add something in cdylib

wfassoc-cdylib/src/cstr_ffi.rs

@@ -12,6 +12,9 @@ use std::cell::RefCell;
 use std::ffi::{CStr, CString, c_char};
 use thiserror::Error as TeError;
 
+/// The type representing the raw pointer to immutable C-style NUL-terminated string.
+pub type CStyleString = *const c_char;
+
 // region: Error
 
 /// Error occurs in this crate.
@@ -31,13 +34,13 @@ type Result<T> = std::result::Result<T, Error>;
 
 // endregion
 
-// region: FFI String
+// region: String Cache for Exposing
 
-struct FfiString {
+struct StringCache {
     msg: CString,
 }
 
-impl FfiString {
+impl StringCache {
     fn new() -> Self {
         Self {
             msg: CString::new("").expect("empty string must be valid for CString"),
@@ -49,7 +52,7 @@ impl FfiString {
         Ok(())
     }
 
-    pub fn get_msg(&self) -> *const c_char {
+    pub fn get_msg(&self) -> CStyleString {
         self.msg.as_ptr()
     }
 
@@ -63,7 +66,7 @@ impl FfiString {
 // region: Exposed Functions
 
 thread_local! {
-    static STRING_CACHE: RefCell<FfiString> = RefCell::new(FfiString::new());
+    static STRING_CACHE: RefCell<StringCache> = RefCell::new(StringCache::new());
 }
 
 /// Set thread local string exposed for C code.
@@ -74,7 +77,7 @@ pub fn set_ffi_string(msg: &str) -> Result<()> {
 }
 
 /// Get const pointer to thread local string exposed for C code.
-pub fn get_ffi_string() -> *const c_char {
+pub fn get_ffi_string() -> CStyleString {
     STRING_CACHE.with(|e| e.borrow().get_msg())
 }
 
@@ -88,7 +91,7 @@ pub fn clear_ffi_string() {
 }
 
 /// Parse string given by C code into Rust string.
-pub fn parse_ffi_string<'a>(ptr: *const c_char) -> Result<&'a str> {
+pub fn parse_ffi_string<'a>(ptr: CStyleString) -> Result<&'a str> {
     if ptr.is_null() {
         Err(Error::NullPtr)
     } else {