通过一个shared_ptr访问calloc'd数据 [英] Accessing calloc'd data through a shared_ptr

问题描述

我试图访​​问我美元，在释放calloc 方法通过一个shared_ptr pviously分配p $的数据。出于某种原因，我不能访问它（保持与 EXC_BAD_ACCESS 崩溃）在 glTexImage2D （我的$的最后一行C $ç段）。

I'm trying to access the data that I previously allocated with the calloc method through a shared_ptr. For some reason I can't access it (keeps on crashing with EXC_BAD_ACCESS) on glTexImage2D (last line of my code snippets).

我UTIL方法加载数据：

My util method to load the data:

shared_ptr<ImageData> IOSFileSystem::loadImageFile(string path) const
{
    // Result
    shared_ptr<ImageData> result = shared_ptr<ImageData>();

    ...

    // Check if file exists
    if([[NSFileManager defaultManager] fileExistsAtPath:fullPath isDirectory:NO])
    {
        ...

        GLubyte *spriteData = (GLubyte*) calloc(width * height * 4, sizeof(GLubyte));

        ...

        // Put result in shared ptr
        shared_ptr<GLubyte> spriteDataPtr = shared_ptr<GLubyte>(spriteData);
        result = shared_ptr<ImageData>(new ImageData(path, width, height, spriteDataPtr));
    }
    else
    {
        cout << "IOSFileSystem::loadImageFile -> File does not exist at path.\nPath: " + path;
        exit(1);
    }

    return result;
}

头为的ImageData ：

class ImageData
{
public:
    ImageData(string path, int width, int height, shared_ptr<GLubyte> data);
    ~ImageData();

    string getPath() const;

    int getWidth() const;
    int getHeight() const;

    shared_ptr<GLubyte> getData() const;

private:
    string path;

    int width;
    int height;

    shared_ptr<GLubyte> data;
};

文件调用的Util类：

File that calls the util class:

void TextureMaterial::load()
{
    shared_ptr<IFileSystem> fileSystem = ServiceLocator::getFileSystem();
    shared_ptr<ImageData> imageData = fileSystem->loadImageFile(path);

    this->bind(imageData);
}



void TextureMaterial::bind(shared_ptr<ImageData> data)
{
    // Pointer to pixel data
    shared_ptr<GLubyte> pixelData = data->getData();

    ...

    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, data->getWidth(), data->getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, &pixelData);
}

只是为了记录：如果我扔掉了所有的shared_ptr的我能够访问数据。签名 glTexImage2D ：

void glTexImage2D(GLenum target, GLint level, GLint internalFormat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid *data);

其他问题：通常你必须释放（spriteData），但因为我给的数据一个shared_ptr，会当的shared_ptr被删除的数据free'd

Additional question: normally you have to free(spriteData) but since I gave the data to a shared_ptr, will the data be free'd when the shared_ptr is removed?

推荐答案

我觉得这是你的问题：

..., &pixelData);

您正在一个局部变量的地址（类型为的shared_ptr＆LT; GLubyte＆GT; ），它是默默转换为无效* ，而不是得到从它的指针。其替换为：

You are taking an address of a local variable (of type shared_ptr<GLubyte>), which is silently cast to void*, instead of getting the pointer from it. Replace it with:

..., pixelData.get());

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