feat: EvalState.realise_string

(cherry picked from commit f2b1142018fd64dd45ec97f1eccf0c48cc4a8c6d)

rust/nix-store/src/path.rs

@@ -0,0 +1,33 @@
+use anyhow::Result;
+use nix_c_raw as raw;
+use nix_util::string_return::{callback_get_vec_u8, callback_get_vec_u8_data};
+
+pub struct StorePath {
+    raw: *mut raw::StorePath,
+}
+impl StorePath {
+    pub fn new_raw_clone(raw: *const raw::StorePath) -> Self {
+        Self::new_raw(unsafe { raw::store_path_clone(raw as *mut raw::StorePath) })
+    }
+    pub fn new_raw(raw: *mut raw::StorePath) -> Self {
+        StorePath { raw }
+    }
+    pub fn name(&self) -> Result<String> {
+        unsafe {
+            let mut vec = Vec::new();
+            raw::store_path_name(
+                self.raw,
+                Some(callback_get_vec_u8),
+                callback_get_vec_u8_data(&mut vec),
+            );
+            String::from_utf8(vec).map_err(|e| e.into())
+        }
+    }
+}
+impl Drop for StorePath {
+    fn drop(&mut self) {
+        unsafe {
+            raw::store_path_free(self.raw);
+        }
+    }
+}