Method SetEndOfFile

libcppcryptfs/file/cryptfile.cpp:671–777

re-writes last block of necessary to account for file growing or shrinking if bSet is TRUE (the default), actually calls SetEndOfFile()

// re-writes last block of necessary to account for file growing or shrinking
// if bSet is TRUE (the default), actually calls SetEndOfFile()
BOOL
CryptFileForward::SetEndOfFile(LONGLONG offset, BOOL bSet)
{
	if (m_real_file_size == (long long)-1)
		return FALSE;

	if (m_handle == NULL || m_handle == INVALID_HANDLE_VALUE)
		return FALSE;

	if (m_is_empty && offset != 0) {
		if (!WriteVersionAndFileId())
			return FALSE;
	}

	LARGE_INTEGER size_down;

	size_down.QuadPart = m_real_file_size;

	if (!adjust_file_offset_down(size_down)) {
		return FALSE;
	}

	LARGE_INTEGER up_off;

	if (bSet) {
		up_off.QuadPart = offset;
		if (!adjust_file_offset_up_truncate_zero(up_off))
			return FALSE;
	}

	long long last_block;
	int to_write;

	bool growing = false;

	if (offset < size_down.QuadPart) {
		last_block = offset / PLAIN_BS;
		to_write = (int)(offset % PLAIN_BS);
	} else if (offset > size_down.QuadPart) {
		last_block = size_down.QuadPart / PLAIN_BS;
		to_write = size_down.QuadPart % PLAIN_BS ? (int)min(PLAIN_BS, offset - size_down.QuadPart) : 0;
		growing = true;
	} else {
		to_write = 0;
	}

	if (to_write == 0) { 
		if (bSet) {
			return SetEndOfFileInternal(up_off);
		} else {
			return TRUE;
		}
	}

	// need to re-write truncated or expanded last block

	unsigned char buf[PLAIN_BS];