Fix memory leak

rust-bindings/build.rs

@@ -40,6 +40,7 @@ fn main() {
         .allowlist_function("filter_match")
         .allowlist_function("filter_match_any")
         .allowlist_function("free_slice")
+        .allowlist_function("free_filter")
         .parse_callbacks(Box::new(bindgen::CargoCallbacks::new()))
         .generate()
         .expect("Unable to generate bindings");

rust-bindings/src/lib.rs

@@ -41,7 +41,7 @@ impl Drop for EncodedFilter {
 }
 
 /// A BIP 158 filter.
-pub struct Bip158Filter(bindings::GCSFilter);
+pub struct Bip158Filter(*const bindings::GCSFilter);
 
 impl Bip158Filter {
     /// Encode a BIP 158 filter from a list of slices.
@@ -62,11 +62,7 @@ impl Bip158Filter {
     /// Encodes the filter.
     pub fn encode(&self) -> EncodedFilter {
         // SAFETY: The `GCSFilter` struct is guaranteed to be valid for the lifetime of the `Bip158Filter` struct.
-        unsafe {
-            EncodedFilter(bindings::encode_filter(
-                &self.0 as *const bindings::GCSFilter,
-            ))
-        }
+        unsafe { EncodedFilter(bindings::encode_filter(self.0)) }
     }
 
     /// Matches a single slice against the filter.
@@ -75,7 +71,7 @@ impl Bip158Filter {
         // struct is guaranteed to be valid for the lifetime of the `Bip158Filter` struct, so this should be safe.
         unsafe {
             bindings::filter_match(
-                &self.0 as *const bindings::GCSFilter,
+                self.0,
                 bindings::Slice {
                     bytes: slice.as_ptr(),
                     length: slice.len(),
@@ -97,13 +93,14 @@ impl Bip158Filter {
 
         // SAFETY: The length provided matches the number of slices, and the `GCSFilter`
         // struct is guaranteed to be valid for the lifetime of the `Bip158Filter` struct, so this should be safe.
-        unsafe {
-            bindings::filter_match_any(
-                &self.0 as *const bindings::GCSFilter,
-                slices.as_ptr(),
-                slices.len(),
-            )
-        }
+        unsafe { bindings::filter_match_any(self.0, slices.as_ptr(), slices.len()) }
+    }
+}
+
+impl Drop for Bip158Filter {
+    fn drop(&mut self) {
+        // SAFETY: The `Slice` struct is guaranteed to be valid for the lifetime of the `EncodedFilter` struct.
+        unsafe { bindings::free_filter(self.0) }
     }
 }
 

rust-bindings/wrapper.cpp

@@ -12,9 +12,9 @@ GCSFilter::ElementSet create_element_set(Slice const* hashes, size_t length) {
     return elements;
 }
 
-GCSFilter create_filter(Slice const* hashes, size_t length) {
+GCSFilter const* create_filter(Slice const* hashes, size_t length) {
     auto elements = create_element_set(hashes, length);
-    return GCSFilter({0, 0, 20, 1 << 20}, elements);
+    return new GCSFilter({0, 0, 20, 1 << 20}, elements);
 }
 
 Slice encode_filter(GCSFilter const* filter) {
@@ -39,4 +39,8 @@ bool filter_match_any(GCSFilter const* filter, Slice const* hashes, size_t lengt
 
 void free_slice(Slice slice) {
     delete[] slice.bytes;
+}
+
+void free_filter(GCSFilter const* filter) {
+    delete filter;
 }

rust-bindings/wrapper.h

@@ -5,8 +5,9 @@ struct Slice {
     const size_t length;
 };
 
-GCSFilter create_filter(Slice const* hashes, size_t length);
+GCSFilter const* create_filter(Slice const* hashes, size_t length);
 Slice encode_filter(GCSFilter const* filter);
 bool filter_match(GCSFilter const* filter, Slice hash);
 bool filter_match_any(GCSFilter const* filter, Slice const* hashes, size_t length);
-void free_slice(Slice slice);
+void free_slice(Slice slice);
+void free_filter(GCSFilter const* filter);