對象破壞時內存泄漏

Question

我有一個玩具項目，它是一個游戲引擎。 它使用SDL2和C ++ 11。 在下面的代碼中，我嘗試在析構函數中創建一個清除內存的對象。 但出了問題，一些內存泄漏。 我究竟做錯了什么？

示例是觸發泄漏的最小工作代碼。 我認為它的工作方式如下：類的實例Game on costruction創建了SDLEngine和Graphics實例（按此順序），兩者都分配了一些內存。 當game對象被破壞時，它會調用Graphics和SDLEngine析構函數（按此順序）。 如果我在這兩個析構函數中添加一些打印，它們將按所需順序打印。 但是valgrind認為由SDL_Init()和SDL_CreateWindow()分配的內存被泄露。

編輯：這可能是valgrind的行為。 我在相當基本的SDL示例中看到了類似的問題和類似的警告： 為什么valgrind說基本的SDL程序泄漏了內存？

SRC /泄漏TEST.CPP：

#include <SDL2/SDL.h>
#include <stdexcept>

class SDLEngine {
public:
    SDLEngine() {
        if (SDL_Init(SDL_INIT_VIDEO) != 0) {
            throw std::runtime_error("SDL_Init"); // line 7
        }
        if (SDL_ShowCursor(SDL_DISABLE) < 0) {
            throw std::runtime_error("SDL_ShowCursor");
        }
    }
    ~SDLEngine() {
        SDL_Quit();
    }
};

class Graphics {
public:
    Graphics() :
        sdlWindow{SDL_CreateWindow(
                    "LeakTest",
                    SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
                    320, 240,
                    0
                    )} // line 27
    {
        if (sdlWindow == nullptr) {
            throw std::runtime_error("SDL_CreateWindow");
        }
    }
    ~Graphics() {
        SDL_DestroyWindow(sdlWindow);
    }
    Graphics(const Graphics&)=delete;
    Graphics& operator=(const Graphics&)=delete;
private:
    SDL_Window *sdlWindow;
};

class Game {
public:
    Game() :
        sdlEngine_(),
        graphics_() // line 46
    {
        SDL_Event event;
        bool running{true};
        while (running) {
            while (SDL_PollEvent(&event)) {
                switch (event.type) {
                case SDL_KEYDOWN:
                    running = false;
                    break;
                default:
                    break;
                }
            }
        }

    }
    ~Game() {}
private:
    const SDLEngine sdlEngine_;
    Graphics graphics_;
};

int main() {
    Game game; // line 70
    return 0;
}

Makefile文件：

CXX := g++
MKDIR := mkdir -p
CXXFLAGS += `pkg-config --cflags sdl2 SDL2_image`
CXXFLAGS += -Wall -Werror -Wextra -Weffc++ -pedantic -std=c++0x -g
LDFLAGS += `pkg-config --libs sdl2 SDL2_image`
PROG := bin/leak-test
OBJS := $(patsubst src/%.cpp,obj/%.o, $(wildcard src\/*.cpp))
#                         escaped to fool SO parser ^
.PHONY: all clean

all: build

build: $(PROG)

clean:
    rm -rf $(PROG) $(OBJS)

$(PROG): obj/leak-test.o

$(PROG):
    @$(MKDIR) $(dir $@)
    $(CXX) $(CXXFLAGS) $(LDFLAGS) -o $@ $^

obj/%.o : src/%.cpp
    @$(MKDIR) $(dir $@)
    $(CXX) $(CXXFLAGS) -c -MD -o $@ $<

Valgrind輸出：

host:cave-test » valgrind --leak-check=full ./bin/leak-test 
==28815== Memcheck, a memory error detector
==28815== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==28815== Using Valgrind-3.9.0 and LibVEX; rerun with -h for copyright info
==28815== Command: ./bin/leak-test
==28815== 
==28815== 
==28815== HEAP SUMMARY:
==28815==     in use at exit: 66,235 bytes in 506 blocks
==28815==   total heap usage: 19,844 allocs, 19,338 frees, 44,931,400 bytes allocated
==28815== 
==28815== 20 bytes in 2 blocks are definitely lost in loss record 7 of 101
==28815==    at 0x4C274A0: malloc (vg_replace_malloc.c:291)
==28815==    by 0x5BF8829: strdup (strdup.c:42)
==28815==    by 0x7203666: ??? (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==28815==    by 0x7204474: _XimSetICValueData (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==28815==    by 0x71FFA69: _XimLocalCreateIC (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==28815==    by 0x71E6044: XCreateIC (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==28815==    by 0x5111CD2: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x51120F7: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x51055FF: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x510540F: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x507048E: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x400D6E: SDLEngine::SDLEngine() (leak-test.cpp:7)
==28815== 
==28815== 20 bytes in 2 blocks are definitely lost in loss record 8 of 101
==28815==    at 0x4C274A0: malloc (vg_replace_malloc.c:291)
==28815==    by 0x5BF8829: strdup (strdup.c:42)
==28815==    by 0x7203666: ??? (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==28815==    by 0x7204474: _XimSetICValueData (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==28815==    by 0x71FFA69: _XimLocalCreateIC (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==28815==    by 0x71E6044: XCreateIC (in /usr/lib/x86_64-linux-gnu/libX11.so.6.3.0)
==28815==    by 0x5111CD2: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x51120F7: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x51055FF: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x400F11: Graphics::Graphics() (leak-test.cpp:27)
==28815==    by 0x401012: Game::Game() (leak-test.cpp:46)
==28815==    by 0x400D31: main (leak-test.cpp:70)
==28815== 
==28815== 104 bytes in 1 blocks are definitely lost in loss record 60 of 101
==28815==    at 0x4C274A0: malloc (vg_replace_malloc.c:291)
==28815==    by 0xD330A11: ??? (in /usr/lib/mesa-diverted/x86_64-linux-gnu/libGL.so.1.2.0)
==28815==    by 0xD309600: ??? (in /usr/lib/mesa-diverted/x86_64-linux-gnu/libGL.so.1.2.0)
==28815==    by 0xD305E7A: ??? (in /usr/lib/mesa-diverted/x86_64-linux-gnu/libGL.so.1.2.0)
==28815==    by 0xD30660F: glXChooseVisual (in /usr/lib/mesa-diverted/x86_64-linux-gnu/libGL.so.1.2.0)
==28815==    by 0x510ED0E: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x510EF40: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x5103B65: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x51056FB: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x510540F: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x507048E: ??? (in /usr/lib/x86_64-linux-gnu/libSDL2-2.0.so.0.2.0)
==28815==    by 0x400D6E: SDLEngine::SDLEngine() (leak-test.cpp:7)
==28815== 
==28815== LEAK SUMMARY:
==28815==    definitely lost: 144 bytes in 5 blocks
==28815==    indirectly lost: 0 bytes in 0 blocks
==28815==      possibly lost: 0 bytes in 0 blocks
==28815==    still reachable: 66,091 bytes in 501 blocks
==28815==         suppressed: 0 bytes in 0 blocks
==28815== Reachable blocks (those to which a pointer was found) are not shown.
==28815== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==28815== 
==28815== For counts of detected and suppressed errors, rerun with: -v
==28815== ERROR SUMMARY: 3 errors from 3 contexts (suppressed: 7 from 3)

Answer 1

事實證明，這個漏洞屬於X11庫中的SDL層。 這個bug很老，SDL開發人員都知道。 看到這個bugzilla線程： https ：//bugzilla.libsdl.org/show_bug.cgi ？ id = 2086

我現在關閉這個問題。