Downgrade support for v6 databases.

Author: asfernandes

src/burp/BurpTasks.cpp

@@ -532,10 +532,13 @@ void BackupRelationTask::initItem(BurpGlobals* tdgbl, Item& item)
 			if (status->getState() & IStatus::STATE_ERRORS)
 				BURP_abort(&status);
 
-			item.m_att->execute(&status, item.m_tra, 0, m_masterGbl->setSearchPath.c_str(),
-				SQL_DIALECT_CURRENT, nullptr, nullptr, nullptr, nullptr);
+			if (m_masterGbl->setSearchPath.hasData())
+			{
+				item.m_att->execute(&status, item.m_tra, 0, m_masterGbl->setSearchPath.c_str(),
+					SQL_DIALECT_CURRENT, nullptr, nullptr, nullptr, nullptr);
 
-			fb_assert(status->isSuccess());
+				fb_assert(status->isSuccess());
+			}
 		}
 
 		tdgbl->db_handle = item.m_att;

src/burp/backup.epp

@@ -320,6 +320,7 @@ int BACKUP_backup(const TEXT* dbb_file, const TEXT* file_name)
 			fb_assert(false);
 	}
 
+	// get schema list for v6 databases
 	if (tdgbl->runtimeODS >= DB_VERSION_DDL14)
 	{
 		const char* getSchemasSql =

src/common/classes/BlrReader.h

@@ -25,6 +25,7 @@
 
 #include "iberror.h"
 #include "../common/classes/fb_string.h"
+#include "../common/classes/MetaString.h"
 #include "../common/StatusArg.h"
 #include "../jrd/constants.h"
 
@@ -121,6 +122,40 @@ class BlrReader
 		return (b4 << 24) | (b3 << 16) | (b2 << 8) | b1;
 	}
 
+	UCHAR parseHeader()
+	{
+		const auto version = getByte();
+
+		switch (version)
+		{
+			case blr_version4:
+			case blr_version5:
+			//case blr_version6:
+				break;
+
+			default:
+				status_exception::raise(
+					Arg::Gds(isc_metadata_corrupt) <<
+					Arg::Gds(isc_wroblrver2) << Arg::Num(blr_version4) << Arg::Num(blr_version5/*6*/) <<
+						Arg::Num(version));
+		}
+
+		auto code = getByte();
+
+		if (code == blr_flags)
+		{
+			while ((code = getByte()) != blr_end)
+			{
+				const auto len = getWord();
+				seekForward(len);
+			}
+		}
+		else
+			seekBackward(1);
+
+		return version;
+	}
+
 	UCHAR checkByte(UCHAR expected)
 	{
 		UCHAR byte = getByte();
@@ -177,6 +212,12 @@ class BlrReader
 		name.assign(str.c_str());
 	}
 
+	void skipMetaName()
+	{
+		MetaString name;
+		getMetaName(name);
+	}
+
 private:
 	const UCHAR* start;
 	const UCHAR* end;

src/common/classes/GenericMap.h

@@ -299,6 +299,10 @@ class GenericMap : public AutoStorage
 
 	size_t count() const { return mCount; }
 
+	bool hasData() const { return mCount != 0; }
+
+	bool isEmpty() const { return mCount == 0; }
+
 	Accessor accessor()
 	{
 		return Accessor(this);