Ensure safe MT access to relation's formats

Author: AlexPeshkoff

src/dsql/DdlNodes.epp

@@ -8835,12 +8835,11 @@ Format* RelationNode::makeFormat(thread_db* tdbb, jrd_tra* transaction, Cached::
 	{
 		// Find and return the format matching new number of fields
 
-		fb_assert(relation->rel_formats.hasData());
-
-		auto formats = relation->rel_formats.readAccessor();
+		auto formats = relation->getFormats();
+		fb_assert(formats->getCount());
 		for (const auto format : *(formats.getPointer()))
 		{
-			if (format->fmt_count == count + 1)
+			if (format && (format->fmt_count == count + 1))
 			{
 				if (version)
 					*version = format->fmt_version;
@@ -8935,12 +8934,7 @@ Format* RelationNode::makeFormat(thread_db* tdbb, jrd_tra* transaction, Cached::
 	}
 
 	// Link the format block into the world
-	{
-		MutexLockGuard g(relation->rel_formats_grow, FB_FUNCTION);
-
-		relation->rel_formats.grow(format->fmt_version + 1, true);
-		relation->rel_formats.writeAccessor()->value(format->fmt_version) = format;
-	}
+	relation->addFormat(format);
 
 	// Store format in system relation
 

src/jrd/Relation.cpp

@@ -687,6 +687,14 @@ Lock* RelationPermanent::createLock(thread_db* tdbb, MemoryPool& pool, lck_t lck
 	return lock;
 }
 
+void RelationPermanent::addFormat(Format* fmt)
+{
+	MutexLockGuard g(rel_formats_grow, FB_FUNCTION);
+
+	rel_formats.grow(fmt->fmt_version + 1, true);
+	rel_formats.writeAccessor()->value(fmt->fmt_version) = fmt;
+}
+
 
 void GCLock::blockingAst()
 {

src/jrd/Relation.h

@@ -882,8 +882,20 @@ class RelationPermanent : public Firebird::PermanentStorage
 	//			... will be removed
 	void removeDepends(thread_db* tdbb);
 
+	typedef SharedReadVector<Format*, 16> Formats;
+
+private:
 	SharedReadVector<Format*, 16> rel_formats;	// Known record formats
 	Firebird::Mutex rel_formats_grow;	// Mutex to grow rel_formats
+
+public:
+	HazardPtr<Formats::Generation> getFormats()
+	{
+		return rel_formats.readAccessor();
+	}
+
+	void addFormat(Format* fmt);
+
 	Indices			rel_indices;		// Active indices
 	QualifiedName	rel_name;			// ascii relation name
 	MetaId			rel_id;

src/jrd/ini.epp

@@ -85,8 +85,8 @@ namespace
 	unsigned getLatestFormat(thread_db* tdbb, int relId, int maxFieldId)
 	{
 		auto* const relation = MetadataCache::lookupRelation(tdbb, relId, CacheFlag::AUTOCREATE | CacheFlag::NOSCAN);
-		fb_assert(relation && relation->rel_formats.hasData());
-		auto formats = relation->rel_formats.readAccessor();
+		fb_assert(relation);
+		auto formats = relation->getFormats();
 
 		const auto formatNumber = formats->getCount() - 1;
 		fb_assert(formatNumber < MAX_TABLE_VERSIONS);
@@ -1043,9 +1043,7 @@ void INI_init(thread_db* tdbb)
 			format->fmt_version = formatNumber;
 			format->fmt_length = FLAG_BYTES(format->fmt_count);
 
-			// no need in any locking inside ini.epp - we have exclusive access
-			relation->rel_formats.grow(format->fmt_version + 1, true);
-			relation->rel_formats.writeAccessor()->value(format->fmt_version) = format;
+			relation->addFormat(format);
 
 			auto desc = format->fmt_desc.begin();
 
@@ -1089,7 +1087,7 @@ void INI_init(thread_db* tdbb)
 			formatNumber++;
 		}
 
-		const auto* formats = relation->rel_formats.writeAccessor();
+		const auto formats = relation->getFormats();
 		fb_assert(currentFormat < formats->getCount());
 		relVers->rel_current_fmt = currentFormat;
 		relVers->rel_current_format = formats->value(currentFormat);

src/jrd/met.epp

@@ -916,7 +916,7 @@ Format* MET_format(thread_db* tdbb, RelationPermanent* relation, USHORT number)
 	Database* dbb = tdbb->getDatabase();
 
 	Format* format;
-	auto formats = relation->rel_formats.readAccessor();
+	auto formats = relation->getFormats();
 	if ((number < formats->getCount()) && (format = formats->value(number)))
 	{
 		return format;
@@ -987,11 +987,7 @@ Format* MET_format(thread_db* tdbb, RelationPermanent* relation, USHORT number)
 	format->fmt_version = number;
 
 	// Link the format block into the world
-
-	MutexLockGuard g(relation->rel_formats_grow, FB_FUNCTION);
-
-	relation->rel_formats.grow(number + 1, true);
-	relation->rel_formats.writeAccessor()->value(number) = format;
+	relation->addFormat(format);
 
 	return format;
 }