static long dma_heap_ioctl()

in dma-heap.c [125:182]

• 46 lines of code
• 11 McCabe index (conditional complexity)

static long dma_heap_ioctl(struct file *file, unsigned int ucmd,
			   unsigned long arg)
{
	char stack_kdata[128];
	char *kdata = stack_kdata;
	unsigned int kcmd;
	unsigned int in_size, out_size, drv_size, ksize;
	int nr = _IOC_NR(ucmd);
	int ret = 0;

	if (nr >= ARRAY_SIZE(dma_heap_ioctl_cmds))
		return -EINVAL;

	/* Get the kernel ioctl cmd that matches */
	kcmd = dma_heap_ioctl_cmds[nr];

	/* Figure out the delta between user cmd size and kernel cmd size */
	drv_size = _IOC_SIZE(kcmd);
	out_size = _IOC_SIZE(ucmd);
	in_size = out_size;
	if ((ucmd & kcmd & IOC_IN) == 0)
		in_size = 0;
	if ((ucmd & kcmd & IOC_OUT) == 0)
		out_size = 0;
	ksize = max(max(in_size, out_size), drv_size);

	/* If necessary, allocate buffer for ioctl argument */
	if (ksize > sizeof(stack_kdata)) {
		kdata = kmalloc(ksize, GFP_KERNEL);
		if (!kdata)
			return -ENOMEM;
	}

	if (copy_from_user(kdata, (void __user *)arg, in_size) != 0) {
		ret = -EFAULT;
		goto err;
	}

	/* zero out any difference between the kernel/user structure size */
	if (ksize > in_size)
		memset(kdata + in_size, 0, ksize - in_size);

	switch (kcmd) {
	case DMA_HEAP_IOCTL_ALLOC:
		ret = dma_heap_ioctl_allocate(file, kdata);
		break;
	default:
		ret = -ENOTTY;
		goto err;
	}

	if (copy_to_user((void __user *)arg, kdata, out_size) != 0)
		ret = -EFAULT;
err:
	if (kdata != stack_kdata)
		kfree(kdata);
	return ret;
}