Giter Club home page Giter Club logo

glibcmock's Introduction

glibc mock

Build Status Coverage Status Coverage Status Code Health MIT licensed

Welcome to glibc mock, a solution of mocking glibc function (open, read, write โ€ฆ etc.) with Google Test and Google Mock!

Mock glibc function by changing GOT value to custom static function address.

As we know, glibc function address is store in GOT (Global Offset Table).
Change the GOT value to a custom static function address, then the glibc call will call the custom static function actually.
In the custom static function, we make it to call a Google Mock method, then we have mocked the glibc function.

Usage

  1. Copy got_hook.h and got_hook.cc to your C++ test project.
  2. Add #include "got_hook.h" to your test source code.

Sample 1

struct MockMalloc {
    MOCK_METHOD1(Malloc, void *(size_t));
};

static MockMalloc *g_mock{nullptr};

static void *Malloc(size_t size) {
    return g_mock->Malloc(size);
}

static std::mutex g_test_mutex;

TEST(MallocTest, ReturnNull) {
    std::lock_guard<std::mutex> lock(g_test_mutex); // not thread safe
    std::unique_ptr<MockMalloc> mock(g_mock = new MockMalloc());
    testing::GotHook got_hook;
    ASSERT_NO_FATAL_FAILURE(got_hook.MockFunction("malloc", (void*)&Malloc));
    // ... do your test here, for example:
    EXPECT_CALL(*g_mock, Malloc(testing::_)).WillOnce(testing::Return(nullptr));
    EXPECT_EQ(nullptr, malloc(1));
}

Sample 2

constexpr key_t shm_key = 0x123;

struct Turtle {
    void UseSharedMemory() {
        auto shm_id = shmget(shm_key, 0, 0);
        auto buffer = shmat(shm_id, nullptr, 0);
        EXPECT_STREQ("a fake shm buffer", (char*)buffer);
        // ...
        shmdt(buffer);
    }
};

struct MockTurtle : Turtle {
    MOCK_METHOD3(shmget, int(key_t, size_t, int));
    MOCK_METHOD3(shmat, void*(int, const void*, int));
    MOCK_METHOD1(shmdt, int(const void*));
};

static MockTurtle *g_turtle{nullptr};

static int my_shmget(key_t key, size_t size, int shmflg) {
    return g_turtle->shmget(key, size, shmflg);
}

static void *my_shmat(int shmid, const void *shmaddr, int shmflg) {
    return g_turtle->shmat(shmid, shmaddr, shmflg);
}

static int my_shmdt(const void *shmaddr) {
    return g_turtle->shmdt(shmaddr);
}

static std::mutex g_test_mutex;

TEST(TurtleTest, FakeSharedMemory) {
    std::lock_guard<std::mutex> lock(g_test_mutex); // not thread safe
    std::unique_ptr<MockTurtle> turtle(g_turtle = new MockTurtle());
    testing::GotHook got_hook;
    ASSERT_NO_FATAL_FAILURE({
        got_hook.MockFunction("shmget", (void*)&my_shmget);
        got_hook.MockFunction("shmat", (void*)&my_shmat);
        got_hook.MockFunction("shmdt", (void*)&my_shmdt);
    });
    constexpr int shm_id = 100;
    char fake_shm_buffer[2000]{"a fake shm buffer"};
    // ...
    EXPECT_CALL(*g_turtle, shmget(shm_key, _, _)).WillOnce(Return(shm_id));
    EXPECT_CALL(*g_turtle, shmat(shm_id, _, _)).WillOnce(Return(fake_shm_buffer));
    EXPECT_CALL(*g_turtle, shmdt(fake_shm_buffer)).WillOnce(Return(0));
    // ...
    g_turtle->UseSharedMemory();
    // ...
}

Sample 3

constexpr const char *prod_file = "/usr/local/xxx";
constexpr const char *test_file = "/tmp/xxx";

struct Panda {
    void OpenFile() {
        auto fd = open(prod_file, O_RDONLY);
        // ...
        close(fd);
    }
};

struct MockPanda : Panda {
    MOCK_METHOD2(Open, int(const char*, int));
};

static std::mutex g_test_mutex;

static MockPanda *g_panda{nullptr};

static int (*libc_open)(const char*, int, ...);

struct PandaTest : testing::Test {
    testing::GotHook *got_hook{nullptr};

    virtual void SetUp() {
        g_test_mutex.lock(); // not thread safe
        g_panda = new MockPanda();
        ASSERT_NO_FATAL_FAILURE({
            got_hook = new testing::GotHook();
            got_hook->MockFunction("open", (void*)&Open, (void**)&libc_open);
        });
        ON_CALL(*g_panda, Open(_, _)).WillByDefault(Invoke(libc_open));
        // ...
    }

    virtual void TearDown() {
        delete got_hook;
        delete g_panda;
        g_test_mutex.unlock();
    }

    static int Open(const char *pathname, int flags, ...) {
        if (strcmp(prod_file, pathname) == 0) {
            return g_panda->Open(test_file, flags);
        } else {
            if (flags & O_CREAT) {
                va_list arg;
                va_start(arg, flags);
                mode_t mode = va_arg(arg, mode_t);
                va_end(arg);
                return libc_open(pathname, flags, mode);
            } else {
                return libc_open(pathname, flags);
            }
        }
    }
};

TEST_F(PandaTest, OpenTestFile) {
    // ...
    EXPECT_CALL(*g_panda, Open(test_file, O_RDONLY));
    // ...
    g_panda->OpenFile();
    // ...
}

Requirements

For now support Linux 64-bit only. If you need a 32-bit version, contact me [email protected].

  • C++11 or newer
  • Google Test
  • Google Mock

glibcmock's People

Contributors

lonnywong avatar

Recommend Projects

  • React photo React

    A declarative, efficient, and flexible JavaScript library for building user interfaces.

  • Vue.js photo Vue.js

    ๐Ÿ–– Vue.js is a progressive, incrementally-adoptable JavaScript framework for building UI on the web.

  • Typescript photo Typescript

    TypeScript is a superset of JavaScript that compiles to clean JavaScript output.

  • TensorFlow photo TensorFlow

    An Open Source Machine Learning Framework for Everyone

  • Django photo Django

    The Web framework for perfectionists with deadlines.

  • D3 photo D3

    Bring data to life with SVG, Canvas and HTML. ๐Ÿ“Š๐Ÿ“ˆ๐ŸŽ‰

Recommend Topics

  • javascript

    JavaScript (JS) is a lightweight interpreted programming language with first-class functions.

  • web

    Some thing interesting about web. New door for the world.

  • server

    A server is a program made to process requests and deliver data to clients.

  • Machine learning

    Machine learning is a way of modeling and interpreting data that allows a piece of software to respond intelligently.

  • Game

    Some thing interesting about game, make everyone happy.

Recommend Org

  • Facebook photo Facebook

    We are working to build community through open source technology. NB: members must have two-factor auth.

  • Microsoft photo Microsoft

    Open source projects and samples from Microsoft.

  • Google photo Google

    Google โค๏ธ Open Source for everyone.

  • D3 photo D3

    Data-Driven Documents codes.