cargo-credential-libsecret: load libsecret only once

Previously, libsecret was loaded and unloaded multiple times, leading
to issues where calls could run indefinitely due to glib not properly
cleaning up.
Now, libsecret is stored in a OnceLock, ensuring it is only loaded once,
preventing unnecessary unload/reload cycles.

Author: biglben

credential/cargo-credential-libsecret/src/lib.rs

@@ -15,6 +15,7 @@ mod linux {
     use std::ffi::{CStr, CString};
     use std::os::raw::{c_char, c_int};
     use std::ptr::{null, null_mut};
+    use std::sync::OnceLock;
 
     #[allow(non_camel_case_types)]
     type gchar = c_char;
@@ -85,6 +86,21 @@ mod linux {
 
     pub struct LibSecretCredential;
 
+    fn get_libsecret() -> Result<&'static Library, Error> {
+        static LIBSECRET: OnceLock<Library> = OnceLock::new();
+        // unfortunately `get_or_try_init` is not yet stable
+        match LIBSECRET.get() {
+            Some(lib) => Ok(lib),
+            None => {
+                let _ = LIBSECRET.set(unsafe { Library::new("libsecret-1.so.0") }.context(
+                    "failed to load libsecret: try installing the `libsecret` \
+                    or `libsecret-1-0` package with the system package manager",
+                )?);
+                Ok(LIBSECRET.get().unwrap())
+            }
+        }
+    }
+
     fn label(index_url: &str) -> CString {
         CString::new(format!("cargo-registry:{}", index_url)).unwrap()
     }
@@ -114,15 +130,11 @@ mod linux {
         ) -> Result<CredentialResponse, Error> {
             // Dynamically load libsecret to avoid users needing to install
             // additional -dev packages when building this provider.
-            let lib;
+            let lib = get_libsecret()?;
             let secret_password_lookup_sync: Symbol<'_, SecretPasswordLookupSync>;
             let secret_password_store_sync: Symbol<'_, SecretPasswordStoreSync>;
             let secret_password_clear_sync: Symbol<'_, SecretPasswordClearSync>;
             unsafe {
-                lib = Library::new("libsecret-1.so.0").context(
-                    "failed to load libsecret: try installing the `libsecret` \
-                    or `libsecret-1-0` package with the system package manager",
-                )?;
                 secret_password_lookup_sync = lib
                     .get(b"secret_password_lookup_sync\0")
                     .map_err(Box::new)?;