Function SDW_start

src/jrd/sdw.cpp:921–1095

void SDW_start(thread_db* tdbb, const TEXT* file_name,
			   USHORT shadow_number, USHORT file_flags, bool delete_files)
{
/**************************************
 *
 *	S D W _ s t a r t
 *
 **************************************
 *
 * Functional description
 *	Commence shadowing on a previously created shadow file.
 *
 *	<delete_files> is true if we are not actually starting shadowing,
 *	but deleting inaccessible shadow files.
 *
 **************************************/
	SET_TDBB(tdbb);
	Database* dbb = tdbb->getDatabase();

	SyncLockGuard guard(&dbb->dbb_shadow_sync, SYNC_EXCLUSIVE, "SDW_start");

	USHORT header_fetched = 0;

	// check that this shadow has not already been started,
	// (unless it is marked as invalid, in which case it may
	// be an old shadow of the same number)

	Shadow* shadow;
	for (shadow = dbb->dbb_shadow; shadow; shadow = shadow->sdw_next)
	{
		if ((shadow->sdw_number == shadow_number) && !(shadow->sdw_flags & SDW_INVALID))
		{
			return;
		}
	}

	for (shadow = dbb->dbb_shadow; shadow; shadow = shadow->sdw_next)
	{
		if (shadow->sdw_number == shadow_number)
			break;
	}

	// check to see if the shadow is the same as the current database --
	// if so, a shadow file is being accessed as a database

	Firebird::PathName expanded_name(file_name);
	ISC_expand_filename(expanded_name, false);
	PageSpace* pageSpace = dbb->dbb_page_manager.findPageSpace(DB_PAGE_SPACE);
	jrd_file* dbb_file = pageSpace->file;

	if (dbb_file && expanded_name == dbb_file->fil_string)
	{
		if (shadow && (shadow->sdw_flags & SDW_rollover))
			return;

		ERR_post(Arg::Gds(isc_shadow_accessed));
	}