unsigned long arch_get_unmapped_area()

in kernel/syscall.c [57:92]

• 28 lines of code
• 12 McCabe index (conditional complexity)

unsigned long arch_get_unmapped_area(struct file *filp, unsigned long addr,
		unsigned long len, unsigned long pgoff, unsigned long flags)
{
	struct vm_area_struct *vmm;

	if (flags & MAP_FIXED) {
		/* We do not accept a shared mapping if it would violate
		 * cache aliasing constraints.
		 */
		if ((flags & MAP_SHARED) &&
				((addr - (pgoff << PAGE_SHIFT)) & (SHMLBA - 1)))
			return -EINVAL;
		return addr;
	}

	if (len > TASK_SIZE)
		return -ENOMEM;
	if (!addr)
		addr = TASK_UNMAPPED_BASE;

	if (flags & MAP_SHARED)
		addr = COLOUR_ALIGN(addr, pgoff);
	else
		addr = PAGE_ALIGN(addr);

	for (vmm = find_vma(current->mm, addr); ; vmm = vmm->vm_next) {
		/* At this point:  (!vmm || addr < vmm->vm_end). */
		if (TASK_SIZE - len < addr)
			return -ENOMEM;
		if (!vmm || addr + len <= vm_start_gap(vmm))
			return addr;
		addr = vmm->vm_end;
		if (flags & MAP_SHARED)
			addr = COLOUR_ALIGN(addr, pgoff);
	}
}