libsql: fix prepared statement result binding

src/libsql/Statement.cpp

@@ -30,6 +30,12 @@ void CStmt::Destroy()
 		free(m_puiParamLen);
 		m_puiParamLen = NULL;
 	}
+
+	m_vec_param.clear();
+	m_vec_result.clear();
+	m_vec_result_len.clear();
+	m_uiParamCount = 0;
+	m_uiResultCount = 0;
 }
 
 void CStmt::Error(const char * c_pszMsg)
@@ -41,6 +47,8 @@ bool CStmt::Prepare(CAsyncSQL * sql, const char * c_pszQuery)
 {
 	m_pkStmt = mysql_stmt_init(sql->GetSQLHandle());
 	m_stQuery = c_pszQuery;
+	m_uiParamCount = 0;
+	m_uiResultCount = 0;
 
 	if (mysql_stmt_prepare(m_pkStmt, m_stQuery.c_str(), m_stQuery.length()))
 	{
@@ -48,11 +56,7 @@ bool CStmt::Prepare(CAsyncSQL * sql, const char * c_pszQuery)
 		return false;
 	}
 
-	int iParamCount = 0;
-
-	for (unsigned int i = 0; i < m_stQuery.length(); ++i)
-		if (c_pszQuery[i] == '?')
-			++iParamCount;
+	const auto iParamCount = mysql_stmt_param_count(m_pkStmt);
 
 	if (iParamCount)
 	{
@@ -62,13 +66,12 @@ bool CStmt::Prepare(CAsyncSQL * sql, const char * c_pszQuery)
 		m_puiParamLen = (long unsigned int *) calloc(iParamCount, sizeof(long unsigned int));
 	}
 
-	m_vec_result.resize(48);
-	memset(&m_vec_result[0], 0, sizeof(MYSQL_BIND) * 48);
-
-	if (mysql_stmt_bind_result(m_pkStmt, &m_vec_result[0]))
+	const auto iFieldCount = mysql_stmt_field_count(m_pkStmt);
+	if (iFieldCount)
 	{
-		Error("mysql_stmt_bind_result");
-		return 0;
+		m_vec_result.resize(iFieldCount);
+		memset(&m_vec_result[0], 0, sizeof(MYSQL_BIND) * iFieldCount);
+		m_vec_result_len.resize(iFieldCount, 0);
 	}
 
 	return true;
@@ -114,6 +117,7 @@ bool CStmt::BindResult(enum_field_types type, void * p, int iMaxLen)
 	bind->buffer_type	= type;
 	bind->buffer	= (void *) p;
 	bind->buffer_length	= iMaxLen;
+	bind->length	= &m_vec_result_len[m_uiResultCount - 1];
 	return true;
 }
 
@@ -130,9 +134,21 @@ int CStmt::Execute()
 		MYSQL_BIND * bind = &m_vec_param[i];
 
 		if (bind->buffer_type == MYSQL_TYPE_STRING)
-		{
 			*(m_puiParamLen + i) = strlen((const char *) bind->buffer);
-			sys_log(0, "param %d len %d buf %s", i, *m_puiParamLen, (const char *) bind->buffer);
+	}
+
+	if (!m_vec_result.empty())
+	{
+		if (m_uiResultCount != m_vec_result.size())
+		{
+			sys_log(0, "Result binding not enough %d, expected %d query: %s", m_uiResultCount, m_vec_result.size(), m_stQuery.c_str());
+			return 0;
+		}
+
+		if (mysql_stmt_bind_result(m_pkStmt, &m_vec_result[0]))
+		{
+			Error("mysql_stmt_bind_result");
+			return 0;
 		}
 	}
 
@@ -157,3 +173,10 @@ bool CStmt::Fetch()
 	return !mysql_stmt_fetch(m_pkStmt);
 }
 
+unsigned long CStmt::GetResultLength(unsigned int index) const
+{
+	if (index >= m_vec_result_len.size())
+		return 0;
+
+	return m_vec_result_len[index];
+}

src/libsql/Statement.h

@@ -17,6 +17,7 @@ class CStmt
 		bool    BindResult(enum_field_types type, void * p, int iMaxLen=0);
 		int	Execute();
 		bool    Fetch();
+		unsigned long GetResultLength(unsigned int index) const;
 
 		void    Error(const char * c_pszMsg);
 
@@ -35,6 +36,7 @@ class CStmt
 		long unsigned int *	m_puiParamLen;
 
 		std::vector<MYSQL_BIND> m_vec_result;
+		std::vector<unsigned long> m_vec_result_len;
 		unsigned int            m_uiResultCount;
 };