glfwPollEvents()触发Access violation，OpenGL程序崩溃求助

启动C++ OpenGL程序后初期运行正常，但数秒后崩溃，退出码为-1073741819（对应十六进制错误码C0000005：缓冲区溢出）。调试时得到异常信息：

Exception thrown at 0x00007FFD28144921 (igxelpicd64.dll) in App.exe: 0xC0000005: Access violation writing location 0x0000025170620000.

程序代码如下：

#include <GL/glew.h>
#include <GLFW/glfw3.h>

#include <iostream>
#include <fstream>
#include <string>
#include <sstream>

struct ShaderProgramSource
{
    std::string VertexSource;
    std::string FragmentSource;
};

static ShaderProgramSource parseShader(const std::string& filepath)
{
    std::ifstream stream(filepath);

    enum class ShaderType
    {
        NONE = -1, VERTEX = 0, FRAGMENT = 1
    };

    std::string line;
    std::stringstream ss[2];
    ShaderType type = ShaderType::NONE;
    while (getline(stream, line))
    {
        if (line.find("#shader") != std::string::npos)
        {
            if (line.find("vertex") != std::string::npos)
                type = ShaderType::VERTEX;
            else if (line.find("fragment") != std::string::npos)
                type = ShaderType::FRAGMENT;
        }
        else
        {
            ss[(int)type] << line << '\n';
        }
    }

    return { ss[0].str(), ss[1].str() };
}

typedef unsigned int uint;

static uint compileShader(const std::string& source, uint type)
{
    uint id = glCreateShader(type);
    const char* src = source.c_str();
    glShaderSource(id, 1, &src, nullptr);
    glCompileShader(id);

    int result;
    glGetShaderiv(id, GL_COMPILE_STATUS, &result);
    if (result == GL_FALSE)
    {
        int length;
        glGetShaderiv(id, GL_INFO_LOG_LENGTH, &length);
        //char* message = (char*)alloca(length * sizeof(char));
        char* message = new char[length];
        glGetShaderInfoLog(id, length, &length, message);
        std::cout << "Failed to compile the " << (type == GL_VERTEX_SHADER ? "vertex" : "fragment")
            << " shader !" << std::endl;
        std::cout << message << std::endl;
        delete[](message);
        glDeleteShader(id);
        return EXIT_FAILURE;
    }

    return id;
}

static uint CreateShader(const std::string& vertexShader, const std::string& fragmentShader)
{
    uint program = glCreateProgram();
    uint vs = compileShader(vertexShader, GL_VERTEX_SHADER);
    uint fs = compileShader(fragmentShader, GL_FRAGMENT_SHADER);

    glAttachShader(program, vs);
    glAttachShader(program, fs);
    glLinkProgram(program);
    glValidateProgram(program);

    glDeleteShader(vs);
    glDeleteShader(fs);

    return program;
}

int main(void)
{
    GLFWwindow* window;

    /* Initialize the library */
    if (!glfwInit())
        return -1;

    /* Create a windowed mode window and its OpenGL context */
    window = glfwCreateWindow(640, 480, "Hello Triangle", NULL, NULL);
    if (!window)
    {
        glfwTerminate();
        return -1;
    }

    /* Make the window's context current */
    glfwMakeContextCurrent(window);

    auto state = glewInit();
    if (state != GLEW_OK)
    {
        std::cerr << "Error initializing GLEW" << std::endl;
        return EXIT_FAILURE;
    }

    std::cout << glGetString(GL_VERSION) << std::endl;

    float positions[6] = {
        -0.5f, -0.5f,
         0.0f,  0.5f,
         0.5f, -0.5f
    };

    unsigned int buffer;
    glGenBuffers(1, &buffer);
    glBindBuffer(GL_ARRAY_BUFFER, buffer);
    glBufferData(GL_ARRAY_BUFFER, 6 * sizeof(float), positions, GL_STATIC_DRAW);
    glEnableVertexAttribArray(0);
    glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, sizeof(float) * 2, 0);

    ShaderProgramSource source = parseShader("res/shaders/basic.shader");

    std::cout << "VERTEX" << std::endl;
    std::cout << source.VertexSource << std::endl;
    std::cout << "FRAGMENT" << std::endl;
    std::cout << source.FragmentSource << std::endl;

    //uint shader = CreateShader(source.VertexSource, source.VertexSource);
    //glUseProgram(shader);

    /* Loop until the user closes the window */
    while (!glfwWindowShouldClose(window))
    {
        /* Render here */
        glClear(GL_COLOR_BUFFER_BIT);

        glDrawArrays(GL_TRIANGLES, 0, 3);

        /* Swap front and back buffers */
        glfwSwapBuffers(window);

        /* Poll for and process events */
        glfwPollEvents();
    }

    //glDeleteProgram(shader);

    glfwTerminate();
    return 0;
}

崩溃根源是未启用自定义着色器就执行绘制调用，同时Intel显卡驱动在处理无着色器的OpenGL绘制时存在缓冲区访问漏洞。另外代码还存在数组越界的潜在风险。

具体修复步骤： #

1. 启用并修复着色器程序
   取消注释着色器相关代码，同时修正CreateShader的参数错误（原代码误将顶点着色器传入两次）：

   uint shader = CreateShader(source.VertexSource, source.FragmentSource);
   glUseProgram(shader);
   

   退出前取消注释着色器销毁代码：

   glDeleteProgram(shader);
   

2. 修复parseShader的数组越界问题
   在写入字符串流前判断type是否有效，避免非法访问索引-1：

   else
   {
       if (type != ShaderType::NONE)
       {
           ss[(int)type] << line << '\n';
       }
   }
   

3. 确保 shader 文件合法
   确认res/shaders/basic.shader存在且格式正确，示例内容如下：

   #shader vertex
   #version 330 core
   layout(location = 0) in vec2 aPos;
   void main()
   {
       gl_Position = vec4(aPos.x, aPos.y, 0.0, 1.0);
   }
   
   #shader fragment
   #version 330 core
   out vec4 FragColor;
   void main()
   {
       FragColor = vec4(1.0, 0.5, 0.2, 1.0);
   }
   

完成以上修改后，程序即可稳定运行。

内容的提问来源于stack exchange，提问作者Lemoine Maxence