Easily detect uncommitted changes to the SVM global state (#422)

* uncommitted changes detection

* Fix results and add doc test

Author: neysofu

crates/runtime-ffi/src/api.rs

@@ -477,6 +477,38 @@ pub unsafe extern "C" fn svm_call(
     )
 }
 
+/// Detects if the given runtime contains any uncommitted changes in memory; if
+/// it does, then it returns an error wrapped inside [`svm_result_t`].
+///
+/// # Examples
+///
+/// ```rust
+/// use svm_runtime_ffi::*;
+///
+/// let mut runtime = std::ptr::null_mut();
+///
+/// unsafe { svm_init(true, std::ptr::null(), 0); }
+///
+/// let res = unsafe { svm_runtime_create(&mut runtime) };
+/// assert!(res.is_ok());
+///
+/// let res = unsafe { svm_uncommitted_changes(runtime) };
+/// assert!(res.is_ok());
+/// ```
+///
+#[must_use]
+#[no_mangle]
+pub unsafe extern "C" fn svm_uncommitted_changes(runtime_ptr: *mut c_void) -> svm_result_t {
+    catch_unwind_or_fail(|| {
+        let runtime = get_runtime(runtime_ptr);
+        if runtime.has_uncommitted_changes()? {
+            svm_result_t::new_error(b"The SVM global state contains uncommitted changes.")
+        } else {
+            svm_result_t::OK
+        }
+    })
+}
+
 /// Writes the current state root hash at `hash` and the current layer at `layer`.
 #[must_use]
 #[no_mangle]

crates/runtime/src/runtime/runtime.rs

@@ -687,6 +687,12 @@ impl Runtime {
         Ok(())
     }
 
+    /// Returns [`true`] iff the underlying [`GlobalState`] has changed since
+    /// the last call to [`Runtime::commit`].
+    pub fn has_uncommitted_changes(&self) -> Result<bool> {
+        Ok(self.gs.has_uncommitted_changes())
+    }
+
     /// Given the address of an account, it attempts to read:
     ///
     /// - balance;

crates/state/src/global_state.rs

@@ -98,6 +98,12 @@ impl GlobalState {
         Ok(())
     }
 
+    /// Returns [`true`] iff there are any dirty changes in memory; [`false`]
+    /// otherwise.
+    pub fn has_uncommitted_changes(&self) -> bool {
+        self.storage().has_uncommitted_changes()
+    }
+
     // GETTER/SETTER UTILITIES
     // -----------------------
 

crates/state/src/storage.rs

@@ -122,6 +122,10 @@ impl Storage {
         assert!(layer_id < self.next_layer.id);
     }
 
+    pub fn has_uncommitted_changes(&self) -> bool {
+        !self.dirty_changes.is_empty()
+    }
+
     /// Fetches the value associated with the Blake3 hash of `key`. See
     /// [`Storage::get_by_hash`] for more information.
     ///