C++ Area::GetBaseAddress方法代码示例

int clone_area(const char name[], void **clone_addr, int searchFlags,
	PageProtection protection, int sourceArea)
{
	Area *area = static_cast<Area*>(GetResource(sourceArea, OBJ_AREA));
	if (area == 0) {
		printf("clone_area: source area id %08x is invalid\n", sourceArea);
		return E_BAD_HANDLE;
	}

	unsigned int addr = INVALID_PAGE;
	if (searchFlags & EXACT_ADDRESS)
		addr = reinterpret_cast<unsigned int>(*clone_addr);
		
	// It is important that CreateArea not incur a fault!		
	char nameCopy[OS_NAME_LENGTH];
	if (!CopyUser(nameCopy, name, OS_NAME_LENGTH))
		return E_BAD_ADDRESS;

	Area *newArea = AddressSpace::GetCurrentAddressSpace()->CreateArea(nameCopy, area->GetSize(), AREA_NOT_WIRED,
		protection | USER_READ | SYSTEM_READ | ((protection & USER_WRITE)
		? SYSTEM_WRITE : 0), area->GetPageCache(), 0, addr, searchFlags);
	area->ReleaseRef();
	if (newArea == 0)
		return E_ERROR;

	*clone_addr = reinterpret_cast<void*>(newArea->GetBaseAddress());
	return OpenHandle(newArea);
}

int create_area(const char name[], void **requestAddr, int flags, unsigned int size,
	AreaWiring lock, PageProtection protection)
{
	unsigned int va = INVALID_PAGE;
	if (flags & EXACT_ADDRESS)
		va = reinterpret_cast<unsigned int>(*requestAddr);
		
	PageCache *cache = new PageCache;
	if (cache == 0)
		return E_NO_MEMORY;	

	// It is important that CreateArea not incur a fault!		
	char nameCopy[OS_NAME_LENGTH];
	if (!CopyUser(nameCopy, name, OS_NAME_LENGTH))
		return E_BAD_ADDRESS;

	Area *newArea = AddressSpace::GetCurrentAddressSpace()->CreateArea(nameCopy, size, lock,
		protection | USER_READ | SYSTEM_READ | ((protection & USER_WRITE)
		? SYSTEM_WRITE : 0), cache, 0, va, flags);
	if (newArea == 0) {
		delete cache;
		return E_NO_MEMORY;
	}

	*requestAddr = reinterpret_cast<void*>(newArea->GetBaseAddress());		
	return OpenHandle(newArea);
}

status_t AddressSpace::HandleFault(unsigned int va, bool write, bool user)
{
	va &= ~(PAGE_SIZE - 1); // Round down to a page boundry.

	fAreaLock.LockRead();
	int lastChangeCount = fChangeCount;
	Area *area = static_cast<Area*>(fAreas.Find(va));
	if (area == 0) {
		fAreaLock.UnlockRead();
		return E_BAD_ADDRESS;
	}

	PageProtection protection = area->GetProtection();
	if ((user && write && !(protection & USER_WRITE))
		|| (user && !write && !(protection & USER_READ))
		|| (!user && write && !(protection & SYSTEM_WRITE))
		|| (!user && !write && !(protection & SYSTEM_READ))) {
		fAreaLock.UnlockRead();
		return E_NOT_ALLOWED;
	}

	PageCache *cache = area->GetPageCache();
	if (cache == 0) {
		fAreaLock.UnlockRead();
		return E_NOT_ALLOWED;
	}

	bool copy = cache->IsCopy();
	cache->AcquireRef();
	fAreaLock.UnlockRead();
	off_t offset = va - area->GetBaseAddress() + area->GetCacheOffset();
	Page *page = cache->GetPage(offset, write && cache->IsCopy());
	cache->ReleaseRef();
	if (page == 0)
		return E_IO;

	fAreaLock.LockRead();
	if (lastChangeCount != fChangeCount) {
		// Changes have occured to this address.  Make sure that
		// the area hasn't changed underneath the fault handler.
		Area *newArea = static_cast<Area*>(fAreas.Find(va));
		if (newArea != area || newArea->GetPageCache() != cache ||
			newArea->GetCacheOffset() != offset)
			fAreaLock.UnlockRead();
			return E_BAD_ADDRESS;
	}

	// If this is a read from copy-on-write page, it is shared with the
	// original cache.  Mark it read only.
	if (copy && !write)
		protection &= ~(USER_WRITE | SYSTEM_WRITE);

	fPhysicalMap->Map(va, page->GetPhysicalAddress(), protection);
	fAreaLock.UnlockRead();
	AtomicAdd(&fFaultCount, 1);
	return E_NO_ERROR;
}