From 19f1ffa4018277a8d1f0397a576965b6e3efc267 Mon Sep 17 00:00:00 2001
From: Asher Baker <asherkin@limetech.io>
Date: Sun, 6 Feb 2022 16:34:14 +0000
Subject: [PATCH] Stop SQLite results being used before being fetched (#1709)

The DB API requires FetchRow to be called before accessing any values
from a row, but the SQLite driver did not enforce that requirement and
alowed accessing the first row immediately. A plugin developer hit this
when developing against SQLite locally but using MySQL in production,
where the API misuse threw an error as expected.

Resolves #1691
---
 extensions/sqlite/driver/SqResults.cpp | 12 ++++++------
 extensions/sqlite/driver/SqResults.h   |  8 ++++----
 2 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/extensions/sqlite/driver/SqResults.cpp b/extensions/sqlite/driver/SqResults.cpp
index f4c2215b..3bd0be38 100644
--- a/extensions/sqlite/driver/SqResults.cpp
+++ b/extensions/sqlite/driver/SqResults.cpp
@@ -37,7 +37,7 @@
 SqResults::SqResults(SqQuery *query) : 
 	m_pStmt(query->GetStmt()), m_Strings(1024),
 	m_RowCount(0), m_MaxRows(0), m_Rows(NULL),
-	m_CurRow(0), m_NextRow(0)
+	m_CurRow(-1), m_NextRow(0)
 {
 	m_ColCount = sqlite3_column_count(m_pStmt);
 	if (m_ColCount)
@@ -99,7 +99,7 @@ bool SqResults::FieldNameToNum(const char *name, unsigned int *columnId)
 void SqResults::ResetResultCount()
 {
 	m_RowCount = 0;
-	m_CurRow = 0;
+	m_CurRow = -1;
 	m_NextRow = 0;
 	m_pMemory->Reset();
 }
@@ -163,7 +163,7 @@ void SqResults::PushResult()
 
 bool SqResults::MoreRows()
 {
-	return (m_CurRow < m_RowCount);
+	return (m_CurRow < 0) ? (m_RowCount > 0) : (m_CurRow < m_RowCount);
 }
 
 IResultRow *SqResults::FetchRow()
@@ -179,7 +179,7 @@ IResultRow *SqResults::FetchRow()
 
 IResultRow *SqResults::CurrentRow()
 {
-	if (!m_RowCount || m_CurRow >= m_RowCount)
+	if (!m_RowCount || m_CurRow < 0 || m_CurRow >= m_RowCount)
 	{
 		return NULL;
 	}
@@ -188,14 +188,14 @@ IResultRow *SqResults::CurrentRow()
 
 bool SqResults::Rewind()
 {
-	m_CurRow = 0;
+	m_CurRow = -1;
 	m_NextRow = 0;
 	return true;
 }
 
 SqField *SqResults::GetField(unsigned int col)
 {
-	if (m_CurRow >= m_RowCount || col >= m_ColCount)
+	if (m_CurRow < 0 || m_CurRow >= m_RowCount || col >= m_ColCount)
 	{
 		return NULL;
 	}
diff --git a/extensions/sqlite/driver/SqResults.h b/extensions/sqlite/driver/SqResults.h
index afc366a2..1491fb2e 100644
--- a/extensions/sqlite/driver/SqResults.h
+++ b/extensions/sqlite/driver/SqResults.h
@@ -90,11 +90,11 @@ private:
 	unsigned int m_ColCount;	/** DOES NOT CHANGE */
 	BaseStringTable m_Strings;	/** DOES NOT CHANGE */
 	BaseMemTable *m_pMemory;	/** DOES NOT CHANGE */
-	unsigned int m_RowCount;
-	unsigned int m_MaxRows;
+	int m_RowCount;
+	int m_MaxRows;
 	SqField *m_Rows;
-	unsigned int m_CurRow;
-	unsigned int m_NextRow;
+	int m_CurRow;
+	int m_NextRow;
 };
 
 #endif //_INCLUDE_SQLITE_SOURCEMOD_RESULT_SET_H_