database/sql: guard against panics in driver.Stmt implementation

For #13677, but there is more to do.

Change-Id: Id1af999dc972d07cdfc771e5855a1a7dca47ca96
Reviewed-on: https://go-review.googlesource.com/18046
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

1 files changed, 26 insertions, 1 deletions

diff --git a/src/database/sql/fakedb_test.go b/src/database/sql/fakedb_test.go
index f1e8f6cb6e..b5ff121358 100644
--- a/src/database/sql/fakedb_test.go
+++ b/src/database/sql/fakedb_test.go
@@ -33,6 +33,9 @@ var _ = log.Printf
 //   INSERT|<tablename>|col=val,col2=val2,col3=?
 //   SELECT|<tablename>|projectcol1,projectcol2|filtercol=?,filtercol2=?
 //
+// Any of these can be preceded by PANIC|<method>|, to cause the
+// named method on fakeStmt to panic.
+//
 // When opening a fakeDriver's database, it starts empty with no
 // tables.  All tables and data are stored in memory only.
 type fakeDriver struct {
@@ -111,6 +114,7 @@ type fakeStmt struct {
 
 	cmd   string
 	table string
+	panic string
 
 	closed bool
 
@@ -499,9 +503,15 @@ func (c *fakeConn) Prepare(query string) (driver.Stmt, error) {
 	if len(parts) < 1 {
 		return nil, errf("empty query")
 	}
+	stmt := &fakeStmt{q: query, c: c}
+	if len(parts) >= 3 && parts[0] == "PANIC" {
+		stmt.panic = parts[1]
+		parts = parts[2:]
+	}
 	cmd := parts[0]
+	stmt.cmd = cmd
 	parts = parts[1:]
-	stmt := &fakeStmt{q: query, c: c, cmd: cmd}
+
 	c.incrStat(&c.stmtsMade)
 	switch cmd {
 	case "WIPE":
@@ -524,6 +534,9 @@ func (c *fakeConn) Prepare(query string) (driver.Stmt, error) {
 }
 
 func (s *fakeStmt) ColumnConverter(idx int) driver.ValueConverter {
+	if s.panic == "ColumnConverter" {
+		panic(s.panic)
+	}
 	if len(s.placeholderConverter) == 0 {
 		return driver.DefaultParameterConverter
 	}
@@ -531,6 +544,9 @@ func (s *fakeStmt) ColumnConverter(idx int) driver.ValueConverter {
 }
 
 func (s *fakeStmt) Close() error {
+	if s.panic == "Close" {
+		panic(s.panic)
+	}
 	if s.c == nil {
 		panic("nil conn in fakeStmt.Close")
 	}
@@ -550,6 +566,9 @@ var errClosed = errors.New("fakedb: statement has been closed")
 var hookExecBadConn func() bool
 
 func (s *fakeStmt) Exec(args []driver.Value) (driver.Result, error) {
+	if s.panic == "Exec" {
+		panic(s.panic)
+	}
 	if s.closed {
 		return nil, errClosed
 	}
@@ -634,6 +653,9 @@ func (s *fakeStmt) execInsert(args []driver.Value, doInsert bool) (driver.Result
 var hookQueryBadConn func() bool
 
 func (s *fakeStmt) Query(args []driver.Value) (driver.Rows, error) {
+	if s.panic == "Query" {
+		panic(s.panic)
+	}
 	if s.closed {
 		return nil, errClosed
 	}
@@ -716,6 +738,9 @@ rows:
 }
 
 func (s *fakeStmt) NumInput() int {
+	if s.panic == "NumInput" {
+		panic(s.panic)
+	}
 	return s.placeholders
 }