test(scap): add unit tests for scap_cgroup_prefix_path

Signed-off-by: Mauro Ezequiel Moltrasio <mmoltras@redhat.com>
Co-authored-by: Andrea Terzolo <andreaterzolo3@gmail.com>

test/libscap/CMakeLists.txt

@@ -65,6 +65,12 @@ set(LIBSCAP_TESTS_SOURCES ${USERSPACE_TEST_SUITE})
 file(GLOB_RECURSE LIBSCAP_TESTS_UTILS_SOURCES "${CMAKE_CURRENT_SOURCE_DIR}/helpers/*cpp")
 list(APPEND LIBSCAP_TESTS_SOURCES ${LIBSCAP_TESTS_UTILS_SOURCES})
 
+# Linux specific tests
+if (CMAKE_SYSTEM_NAME MATCHES "Linux")
+	file(GLOB_RECURSE LINUX_TEST_SUITE "${CMAKE_CURRENT_SOURCE_DIR}/test_suites/userspace/linux/*.cpp")
+	list(APPEND LIBSCAP_TEST_SOURCES ${LINUX_TEST_SUITE})
+endif()
+
 # Engine-specific tests
 if(BUILD_DRIVER)
 	file(GLOB_RECURSE KMOD_TEST_SUITE "${CMAKE_CURRENT_SOURCE_DIR}/test_suites/engines/kmod/*.cpp")

test/libscap/test_suites/userspace/linux/scap_cgroup.cpp

@@ -0,0 +1,77 @@
+/*
+Copyright (C) 2023 The Falco Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+*/
+
+#include <gtest/gtest.h>
+#include <linux/scap_cgroup.h>
+#include <linux/scap_cgroup.c>
+
+TEST(cgroups, path_relative)
+{
+	char final_path[4096];
+	const char* prefix = "/1/2/3";
+	const char* path = "/../../../init.scope";
+	size_t prefix_len = 0;
+	size_t path_strip_len = 0;
+	ASSERT_EQ(scap_cgroup_prefix_path(prefix, path, &prefix_len, &path_strip_len), SCAP_SUCCESS);
+	snprintf(final_path, sizeof(final_path), "%.*s%s", (int)prefix_len, prefix, path + path_strip_len);
+	ASSERT_STREQ(final_path,"/init.scope");
+}
+
+TEST(cgroups, path_relative_with_final_slash)
+{
+	char final_path[4096];
+	const char* prefix = "/1/2/3/";
+	const char* path = "/../../../init.scope";
+	size_t prefix_len = 0;
+	size_t path_strip_len = 0;
+	ASSERT_EQ(scap_cgroup_prefix_path(prefix, path, &prefix_len, &path_strip_len), SCAP_SUCCESS);
+	snprintf(final_path, sizeof(final_path), "%.*s%s", (int)prefix_len, prefix, path + path_strip_len);
+	ASSERT_STREQ(final_path,"/1/init.scope");
+}
+
+TEST(cgroups, path_absolute)
+{
+	char final_path[4096];
+	const char* prefix = "/1/2/3";
+	const char* path = "/absolute";
+	size_t prefix_len = 0;
+	size_t path_strip_len = 0;
+	ASSERT_EQ(scap_cgroup_prefix_path(prefix, path, &prefix_len, &path_strip_len), SCAP_SUCCESS);
+	snprintf(final_path, sizeof(final_path), "%.*s%s", (int)prefix_len, prefix, path + path_strip_len);
+	ASSERT_STREQ(final_path,"/1/2/3/absolute");
+}
+
+TEST(cgroups, prefix_empty)
+{
+	const char* prefix = "";
+	const char* path = "/../../absolute";
+	size_t prefix_len = 0;
+	size_t path_strip_len = 0;
+	ASSERT_EQ(scap_cgroup_prefix_path(prefix, path, &prefix_len, &path_strip_len), SCAP_FAILURE);
+}
+
+TEST(cgroups, path_empty)
+{
+	char final_path[4096];
+	const char* prefix = "/1/2/3";
+	const char* path = "";
+	size_t prefix_len = 0;
+	size_t path_strip_len = 0;
+	ASSERT_EQ(scap_cgroup_prefix_path(prefix, path, &prefix_len, &path_strip_len), SCAP_SUCCESS);
+	snprintf(final_path, sizeof(final_path), "%.*s%s", (int)prefix_len, prefix, path + path_strip_len);
+	ASSERT_STREQ(final_path,"/1/2/3");
+}

userspace/libscap/linux/scap_cgroup.c

@@ -259,6 +259,9 @@ static const char* scan_back(const char* start, const char* end)
 // slash so that we don't end up with doubled slashes (one from the prefix, one from the path)
 static int32_t scap_cgroup_prefix_path(const char* prefix, const char* path, size_t* prefix_len, size_t* path_strip_len)
 {
+	ASSERT(prefix != NULL);
+	ASSERT(path != NULL);
+
 	const char* prefix_p = prefix + strlen(prefix);
 	const char* path_p = path;
 
@@ -533,7 +536,7 @@ static int32_t get_cgroup_subsystems_v2(struct scap_cgroup_interface* cgi, struc
 
 	if(cgi->m_use_cache)
 	{
-		struct scap_cgroup_cache* cached = malloc(sizeof(*cached));
+		struct scap_cgroup_cache* cached = (struct scap_cgroup_cache*)malloc(sizeof(*cached));
 		if(cached)
 		{
 			int uth_status = SCAP_SUCCESS;