g_array_append_vals断言失败及g_ptr_array_extend_and_steal崩溃问题排查

问题背景 #

开发Vulkan扩展检查的CMake项目时，程序运行后瞬间退出，终端输出断言失败错误。先后尝试GArray和GPtrArray两种容器，均遇到问题：

初始GArray实现的问题 #

使用GArray编写的函数触发g_array_append_vals的'array'断言失败，核心原因是未初始化requiredExtensions数组，指针类型转换尝试无效。

初始代码：

GArray* glfwExtensions, *requiredExtensions;
uint_fast32_t glfwExtensionCount;
bool enableValidationLayers = true;

int __fastcall getRequiredExtensions() {
    glfwExtensions = g_array_new_take((char**)glfwGetRequiredInstanceExtensions(&glfwExtensionCount), glfwExtensionCount, false, __SIZEOF_POINTER__);
    g_array_append_vals(requiredExtensions, (const char**)(glfwExtensions->data), glfwExtensionCount);
    g_array_append_vals(requiredExtensions, (const char*[]){VK_KHR_PORTABILITY_ENUMERATION_EXTENSION_NAME}, 1);

    if (enableValidationLayers)
        g_array_append_vals(requiredExtensions, (const char*[]){VK_EXT_DEBUG_UTILS_EXTENSION_NAME}, 1);

    return EXIT_SUCCESS;
}

终端错误输出：

(proces:8144): GLib-CRITICAL **: 16:31:15.244: g_array_append_vals: assertion 'array' failed

(proces:8144): GLib-CRITICAL **: 16:31:15.260: g_array_append_vals: assertion 'array' failed

(proces:8144): GLib-CRITICAL **: 16:31:15.261: g_array_append_vals: assertion 'array' failed

改用GPtrArray后的问题 #

切换到GPtrArray后，调用g_ptr_array_extend_and_steal时程序崩溃，但单独用g_ptr_array_add添加元素可以正常运行，导致无法批量启用验证层和其他扩展。

修改后代码：

GPtrArray *glfwExtensions, *requiredExtensions;
uint_fast32_t glfwExtensionCount;
bool enableValidationLayers = true;

int __fastcall getRequiredExtensions() {
    {
        const char** glfwExtTemp = (const char**)glfwGetRequiredInstanceExtensions(&glfwExtensionCount);
        glfwExtensions = g_ptr_array_new_take((gpointer*)glfwExtTemp, glfwExtensionCount, NULL);
        requiredExtensions = g_ptr_array_copy(glfwExtensions, NULL, NULL);
    }
    // g_ptr_array_add(requiredExtensions, VK_KHR_PORTABILITY_ENUMERATION_EXTENSION_NAME); <-- 此代码正常运行，原因何在？

    g_ptr_array_extend_and_steal(requiredExtensions, g_ptr_array_new_take((gpointer*)(char*[]){
        VK_KHR_PORTABILITY_ENUMERATION_EXTENSION_NAME,
    }, 1, NULL));

    if (enableValidationLayers)
        g_ptr_array_extend_and_steal(requiredExtensions, g_ptr_array_new_take((gpointer*)(char*[]){
            VK_EXT_DEBUG_UTILS_EXTENSION_NAME,
        }, 1, NULL));

    return EXIT_SUCCESS;
}

问题原因分析 #

g_ptr_array_extend_and_steal崩溃的核心原因是临时栈数组的生命周期问题：

• 代码中(char*[]){VK_KHR_PORTABILITY_ENUMERATION_EXTENSION_NAME}是栈上的临时数组，语句执行结束后会被销毁。
• g_ptr_array_new_take会接管传入的指针数组所有权，但临时数组销毁后，GPtrArray内部持有了野指针。
• 调用g_ptr_array_extend_and_steal时访问这些野指针，触发程序崩溃。
• 而g_ptr_array_add只是添加字符串字面量的指针，字符串字面量存储在程序全局只读数据区，生命周期贯穿整个程序，因此不会出现野指针问题。

解决方案 #

方案1：逐个调用g_ptr_array_add添加扩展 #

直接逐个添加扩展名称，避免临时数组的生命周期问题：

int __fastcall getRequiredExtensions() {
    const char** glfwExtTemp = (const char**)glfwGetRequiredInstanceExtensions(&glfwExtensionCount);
    glfwExtensions = g_ptr_array_new_take((gpointer*)glfwExtTemp, glfwExtensionCount, NULL);
    requiredExtensions = g_ptr_array_copy(glfwExtensions, NULL, NULL);

    // 逐个添加扩展
    g_ptr_array_add(requiredExtensions, VK_KHR_PORTABILITY_ENUMERATION_EXTENSION_NAME);
    
    if (enableValidationLayers) {
        g_ptr_array_add(requiredExtensions, VK_EXT_DEBUG_UTILS_EXTENSION_NAME);
    }

    return EXIT_SUCCESS;
}

方案2：动态分配数组后使用g_ptr_array_new_take #

若需批量添加，可动态分配数组存储扩展名称，确保生命周期足够：

int __fastcall getRequiredExtensions() {
    const char** glfwExtTemp = (const char**)glfwGetRequiredInstanceExtensions(&glfwExtensionCount);
    glfwExtensions = g_ptr_array_new_take((gpointer*)glfwExtTemp, glfwExtensionCount, NULL);
    requiredExtensions = g_ptr_array_copy(glfwExtensions, NULL, NULL);

    // 动态分配数组存储扩展
    gpointer* portabilityExt = g_new(gpointer, 1);
    portabilityExt[0] = (gpointer)VK_KHR_PORTABILITY_ENUMERATION_EXTENSION_NAME;
    g_ptr_array_extend_and_steal(requiredExtensions, g_ptr_array_new_take(portabilityExt, 1, NULL));

    if (enableValidationLayers) {
        gpointer* debugExt = g_new(gpointer, 1);
        debugExt[0] = (gpointer)VK_EXT_DEBUG_UTILS_EXTENSION_NAME;
        g_ptr_array_extend_and_steal(requiredExtensions, g_ptr_array_new_take(debugExt, 1, NULL));
    }

    return EXIT_SUCCESS;
}

方案3：使用g_ptr_array_addv批量添加 #

GLib提供g_ptr_array_addv函数，可直接批量添加指针数组，无需创建临时GPtrArray：

int __fastcall getRequiredExtensions() {
    const char** glfwExtTemp = (const char**)glfwGetRequiredInstanceExtensions(&glfwExtensionCount);
    glfwExtensions = g_ptr_array_new_take((gpointer*)glfwExtTemp, glfwExtensionCount, NULL);
    requiredExtensions = g_ptr_array_copy(glfwExtensions, NULL, NULL);

    // 批量添加扩展数组（末尾需以NULL结尾）
    const gpointer portabilityExts[] = {
        (gpointer)VK_KHR_PORTABILITY_ENUMERATION_EXTENSION_NAME,
        NULL
    };
    g_ptr_array_addv(requiredExtensions, portabilityExts);

    if (enableValidationLayers) {
        const gpointer debugExts[] = {
            (gpointer)VK_EXT_DEBUG_UTILS_EXTENSION_NAME,
            NULL
        };
        g_ptr_array_addv(requiredExtensions, debugExts);
    }

    return EXIT_SUCCESS;
}

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