SWIFT-969 Manually clean up mongoc_uri_t when options validation fails (#520)

Author: kmahar

Sources/MongoSwift/ConnectionString.swift

@@ -4,6 +4,8 @@ import CLibMongoC
 internal class ConnectionString {
     /// Pointer to the underlying `mongoc_uri_t`.
     private let _uri: OpaquePointer
+    /// Tracks whether we have already destroyed the above pointer.
+    private var destroyedPtr = false
 
     /// Initializes a new `ConnectionString` with the provided options.
     internal init(_ connectionString: String, options: MongoClientOptions? = nil) throws {
@@ -13,7 +15,16 @@ internal class ConnectionString {
         }
         self._uri = uri
 
-        try self.applyAndValidateOptions(options)
+        // Due to SR-13355, deinit does not get called if we throw here. If we encounter an error, we need to manually
+        // clean up the pointer. We use a variable to track whether we already destroyed it so that, in the event the
+        // bug is fixed and `deinit` starts being called, we don't start calling `mongoc_uri_destroy` twice.
+        do {
+            try self.applyAndValidateOptions(options)
+        } catch {
+            mongoc_uri_destroy(self._uri)
+            self.destroyedPtr = true
+            throw error
+        }
     }
 
     private func applyAndValidateOptions(_ options: MongoClientOptions?) throws {
@@ -361,7 +372,9 @@ internal class ConnectionString {
 
     /// Cleans up the underlying `mongoc_uri_t`.
     deinit {
-        mongoc_uri_destroy(self._uri)
+        if !self.destroyedPtr {
+            mongoc_uri_destroy(self._uri)
+        }
     }
 
     private var usesDNSSeedlistFormat: Bool {

Sources/MongoSwift/Operations/CountDocumentsOperation.swift

@@ -64,21 +64,28 @@ internal struct CountDocumentsOperation<T: Codable>: Operation {
     internal func execute(using connection: Connection, session: ClientSession?) throws -> Int {
         let opts = try encodeOptions(options: options, session: session)
         var error = bson_error_t()
-        var reply = BSONDocument()
-        let count = self.collection.withMongocCollection(from: connection) { collPtr in
-            self.filter.withBSONPointer { filterPtr in
-                withOptionalBSONPointer(to: opts) { optsPtr in
-                    ReadPreference.withOptionalMongocReadPreference(from: self.options?.readPreference) { rpPtr in
-                        reply.withMutableBSONPointer { replyPtr in
-                            mongoc_collection_count_documents(collPtr, filterPtr, optsPtr, rpPtr, replyPtr, &error)
+
+        return try self.collection.withMongocCollection(from: connection) { collPtr in
+            try self.filter.withBSONPointer { filterPtr in
+                try withOptionalBSONPointer(to: opts) { optsPtr in
+                    try ReadPreference.withOptionalMongocReadPreference(from: self.options?.readPreference) { rpPtr in
+                        try withStackAllocatedMutableBSONPointer { replyPtr in
+                            let count = mongoc_collection_count_documents(
+                                collPtr,
+                                filterPtr,
+                                optsPtr,
+                                rpPtr,
+                                replyPtr,
+                                &error
+                            )
+                            guard count != -1 else {
+                                throw extractMongoError(error: error, reply: BSONDocument(copying: replyPtr))
+                            }
+                            return Int(count)
                         }
                     }
                 }
             }
         }
-
-        guard count != -1 else { throw extractMongoError(error: error, reply: reply) }
-
-        return Int(count)
     }
 }