【游戏逆向】判断内存Page是否可读

摘要：
这个方法可以判断指定内存地址是否可读。

// Memory access check
static bool IsMemoryReadable(uintptr_t base)
{
	size_t length = sizeof(uintptr_t);
	constexpr size_t read_access
	=	(PAGE_READONLY
		| PAGE_READWRITE 
		| PAGE_WRITECOPY 
		| PAGE_EXECUTE_READ 
		| PAGE_EXECUTE_READWRITE 
		| PAGE_EXECUTE_WRITECOPY);
	//structure to pass to virtual query which will be populated with the page's information
	MEMORY_BASIC_INFORMATION mbi = { 0 };

	//virtual query returns information on a page
	//if you don't know what a page is , it's basically a contiguous block of memory
	//query for information starting at base
	if (VirtualQuery(reinterpret_cast<void*>(base), &mbi, sizeof(mbi)))
	{
		//check read protections. if the page has one of the listed access protections, we can successfully read from it
		if (!(mbi.Protect & read_access))
			return false;

		//When a process COMMITS a region of virtual memory, the operating system guarantees that it can maintain all the data 
		//the process stores in the memory either in physical memory or on disk.
		//so check for MEM_COMMIT because this means the page is able to store data
		//if this is MEM_RESERVE OR MEM_FREE we don't want to attempt a read
		if (!(mbi.State & MEM_COMMIT))
			return false;

		//make sure the page is not guarded and has access. attempts to read or access these kinds of pages will result in an access violation
		if (mbi.Protect & (PAGE_GUARD | PAGE_NOACCESS))
			return false;

		//get the start and end of the page
		const auto start = reinterpret_cast<uintptr_t>(mbi.BaseAddress);
		const auto end = static_cast<uintptr_t>(start + mbi.RegionSize);

		//check if our memory is within the readable region.
		return (base >= start) && ((base + length) <= end);
	}
	return false;
}

转载链接： Checking For Readable Memory C++