Fix possible protocol desync with SchemaOnly and auto prepare (#5221)

vonzshik · web-flow · commit 8c0e93b32fbf · 2023-08-25T18:35:44.000+03:00
Fixes #5220
diff --git a/src/Npgsql/NpgsqlDataReader.cs b/src/Npgsql/NpgsqlDataReader.cs
@@ -730,20 +730,21 @@ async Task<bool> NextResultSchemaOnly(bool async, bool isConsuming = false, Canc
                     default:
                         throw Connector.UnexpectedMessageReceived(msg.Code);
                     }
+
+                    if (_statements.Skip(StatementIndex + 1).All(x => x.IsPrepared))
+                    {
+                        // There are no more queries, we're done. Read to the RFQ.
+                        Expect<ReadyForQueryMessage>(await Connector.ReadMessage(async), Connector);
+                    }
                 }
 
                 // Found a resultset
                 if (RowDescription != null)
                     return true;
             }
 
-            // There are no more queries, we're done. Read to the RFQ.
-            if (!_statements.All(s => s.IsPrepared))
-            {
-                Expect<ReadyForQueryMessage>(await Connector.ReadMessage(async), Connector);
-                RowDescription = null;
-                State = ReaderState.Consumed;
-            }
+            RowDescription = null;
+            State = ReaderState.Consumed;
 
             return false;
         }
diff --git a/test/Npgsql.Tests/AutoPrepareTests.cs b/test/Npgsql.Tests/AutoPrepareTests.cs
@@ -514,7 +514,7 @@ await conn.ExecuteNonQueryAsync(
         Assert.That(await conn.ExecuteScalarAsync("SELECT 3"), Is.EqualTo(3));
     }
 
-    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/4404")]
+    [Test, IssueLink("https://github.com/npgsql/npgsql/issues/4404"), IssueLink("https://github.com/npgsql/npgsql/issues/5220")]
     public async Task SchemaOnly()
     {
         await using var dataSource = CreateDataSource(csb =>
@@ -529,6 +529,9 @@ public async Task SchemaOnly()
         {
             await using var reader = await cmd.ExecuteReaderAsync(CommandBehavior.SchemaOnly);
         }
+
+        // Make sure there is no protocol desync due to #5220
+        await cmd.ExecuteScalarAsync();
     }
 
     [Test]

Original file line number	Diff line number	Diff line change
`@@ -514,7 +514,7 @@ await conn.ExecuteNonQueryAsync(`
`514`	`514`	`Assert.That(await conn.ExecuteScalarAsync("SELECT 3"), Is.EqualTo(3));`
`515`	`515`	`}`
`516`	`516`
`517`		`- [Test, IssueLink("https://github.com/npgsql/npgsql/issues/4404")]`
	`517`	`+ [Test, IssueLink("https://github.com/npgsql/npgsql/issues/4404"), IssueLink("https://github.com/npgsql/npgsql/issues/5220")]`
`518`	`518`	`public async Task SchemaOnly()`
`519`	`519`	`{`
`520`	`520`	`await using var dataSource = CreateDataSource(csb =>`
`@@ -529,6 +529,9 @@ public async Task SchemaOnly()`
`529`	`529`	`{`
`530`	`530`	`await using var reader = await cmd.ExecuteReaderAsync(CommandBehavior.SchemaOnly);`
`531`	`531`	`}`
	`532`	`+`
	`533`	`+ // Make sure there is no protocol desync due to #5220`
	`534`	`+ await cmd.ExecuteScalarAsync();`
`532`	`535`	`}`
`533`	`536`
`534`	`537`	`[Test]`