动态数组的C静态指针

Question

I have a modular C program where each module uses static global variables for shared access of variables between functions of the module but not to other modules. Now need a dynamically allocated array that is similarly accessible to all module functions, but I'm not familiar with malloc . Below is a simplified example of what I'm trying to do. This seems like the right way to do it but I'm trigger shy since I can't find any similar examples (and since the real thing is much more complicated). Can I maintain a static pointer like this and use the malloc and free to allocate whatever memory blocks come and go but keeping a good pointer to the current block?

static int *dataBlock = NULL;
static int dataSize = 0, dataCursor = 0;

// Init - called externally
int initData(size) {
    if (dataBlock || dataSize > 0) {
        return -1;
    }
    dataBlock = malloc(sizeof(*dataBlock) * size);
    if (!dataBlock) {
        return -1;
    }
    dataSize = size;
    dataCursor = 0;
    return 0;
}

// Push - called externally
int pushData(value) {
    if (dataCursor >= dataSize) {
        return -1;
    }
    dataBlock[dataCursor] = value;
    dataCursor++;
    return dataCursor;
}

// Free - called externally
void freeData() {
    free(dataBlock);
    dataSize = 0;
    dataCursor = 0;
    dataBlock = NULL;
}

Answer 1

Yes, this will (almost) work. If you access this structure using multiple threads, it will fail.

There is a defect in pushData. It will place the first element at dataBlock[1]. Assume a size of 3:

Call 1 -- dataBlock[1] set

2 -- dataBlock[2] set

3 -- dataBlock[3] set -- out of bounds.