move to allocating c strings from rust

1 files changed, 11 insertions, 46 deletions

diff --git a/src/rust/tor_util/ffi.rs b/src/rust/tor_util/ffi.rs
index af4bfc41af..9a56309365 100644
--- a/src/rust/tor_util/ffi.rs
+++ b/src/rust/tor_util/ffi.rs
@@ -1,56 +1,21 @@
-//! FFI functions, only to be called from C.
+//! FFI functions to announce Rust support during tor startup, only to be
+//! called from C.
 //!
-//! Equivalent C versions of these live in `src/common/compat_rust.c`
 
-use std::mem::forget;
-use std::ffi::CString;
-
-use libc;
-use rust_string::RustString;
-
-/// Free the passed `RustString` (`rust_str_t` in C), to be used in place of
-/// `tor_free`().
-///
-/// # Examples
-/// ```c
-/// rust_str_t r_s = rust_welcome_string();
-/// rust_str_free(r_s);
-/// ```
-#[no_mangle]
-#[cfg_attr(feature = "cargo-clippy", allow(needless_pass_by_value))]
-pub unsafe extern "C" fn rust_str_free(_str: RustString) {
-    // Empty body: Just drop _str and we're done (Drop takes care of it).
-}
-
-/// Lends an immutable, NUL-terminated C String.
-///
-/// # Examples
-/// ```c
-/// rust_str_t r_s = rust_welcome_string();
-/// const char *s = rust_str_get(r_s);
-/// printf("%s", s);
-/// rust_str_free(r_s);
-/// ```
-#[no_mangle]
-pub unsafe extern "C" fn rust_str_get(str: RustString) -> *const libc::c_char {
-    let res = str.as_ptr();
-    forget(str);
-    res
-}
+use libc::c_char;
+use tor_allocate::allocate_and_copy_string;
 
 /// Returns a short string to announce Rust support during startup.
 ///
 /// # Examples
 /// ```c
-/// rust_str_t r_s = rust_welcome_string();
-/// const char *s = rust_str_get(r_s);
-/// printf("%s", s);
-/// rust_str_free(r_s);
+/// char *rust_str = rust_welcome_string();
+/// printf("%s", rust_str);
+/// tor_free(rust_str);
 /// ```
 #[no_mangle]
-pub extern "C" fn rust_welcome_string() -> RustString {
-    let s = CString::new("Tor is running with Rust integration. Please report \
-                          any bugs you encouter.")
-            .unwrap();
-    RustString::from(s)
+pub extern "C" fn rust_welcome_string() -> *mut c_char {
+    let rust_welcome = String::from("Tor is running with Rust integration. Please report \
+                          any bugs you encouter.");
+    allocate_and_copy_string(&rust_welcome)
 }