[thin_dump] Fix leaked shared object handle

thin-provisioning/shared_library_emitter.cc

@@ -8,22 +8,109 @@ using namespace thin_provisioning;
 
 //----------------------------------------------------------------
 
+struct shared_object {
+public:
+	shared_object(const char *shared_lib) {
+		handle_ = dlopen(shared_lib, RTLD_LAZY);
+		if (!handle_)
+			throw runtime_error(dlerror());
+
+		dlerror();    // Clear any existing error
+	}
+
+	virtual ~shared_object() {
+		dlclose(handle_);
+	}
+
+	void *get_symbol(const char *symbol) {
+		void *sym = dlsym(handle_, symbol);
+
+		char *error = dlerror();
+		if (error)
+			throw runtime_error(error);
+
+		return sym;
+	}
+
+	void *handle_;
+};
+
+class shared_emitter : public emitter {
+public:
+	shared_emitter(const char *shared_lib, ostream &out): sobj_(shared_lib) {
+		emitter::ptr (*create_fn)(ostream &out);
+		create_fn = reinterpret_cast<emitter::ptr (*)(ostream &)>(
+				sobj_.get_symbol("create_emitter"));
+		inner_ = create_fn(out);
+	}
+
+	virtual ~shared_emitter() {
+	}
+
+	void begin_superblock(std::string const &uuid,
+			      uint64_t time,
+			      uint64_t trans_id,
+			      boost::optional<uint32_t> flags,
+			      boost::optional<uint32_t> version,
+			      uint32_t data_block_size,
+			      uint64_t nr_data_blocks,
+			      boost::optional<uint64_t> metadata_snap) {
+		inner_->begin_superblock(uuid,
+					 time,
+					 trans_id,
+					 flags,
+					 version,
+					 data_block_size,
+					 nr_data_blocks,
+					 metadata_snap);
+	}
+
+	void end_superblock() {
+		inner_->end_superblock();
+	}
+
+	void begin_device(uint32_t dev_id,
+			  uint64_t mapped_blocks,
+			  uint64_t trans_id,
+			  uint64_t creation_time,
+			  uint64_t snap_time) {
+		inner_->begin_device(dev_id, mapped_blocks, trans_id, creation_time, snap_time);
+	}
+
+	void end_device() {
+		inner_->end_device();
+	}
+
+	void begin_named_mapping(std::string const &name) {
+		inner_->begin_named_mapping(name);
+	}
+
+	void end_named_mapping() {
+		inner_->end_named_mapping();
+	}
+
+	void identifier(std::string const &name) {
+		inner_->identifier(name);
+	}
+
+	void range_map(uint64_t origin_begin, uint64_t data_begin, uint32_t time, uint64_t len) {
+		inner_->range_map(origin_begin, data_begin, time, len);
+	}
+
+	void single_map(uint64_t origin_block, uint64_t data_block, uint32_t time) {
+		inner_->single_map(origin_block, data_block, time);
+	}
+
+	shared_object sobj_;
+	emitter::ptr inner_;
+};
+
+//----------------------------------------------------------------
+
 emitter::ptr
 thin_provisioning::create_custom_emitter(string const &shared_lib, ostream &out)
 {
-	emitter::ptr (*create_fn)(ostream &out);
-	void *handle = dlopen(shared_lib.c_str(), RTLD_LAZY);
-	if (!handle)
-		throw runtime_error(dlerror());
-
-	dlerror();    // Clear any existing error
-	create_fn = reinterpret_cast<emitter::ptr (*)(ostream &)>(dlsym(handle, "create_emitter"));
-
-	char *error = dlerror();
-	if (error)
-		throw runtime_error(error);
-
-	return create_fn(out);
+	return emitter::ptr(new shared_emitter(shared_lib.c_str(), out));
 }
 
 //----------------------------------------------------------------