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cgosqlite: fix memory leak in ExpandedSQL #115

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Merged
merged 1 commit into from
Nov 2, 2025
Merged

cgosqlite: fix memory leak in ExpandedSQL #115

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6 changes: 5 additions & 1 deletion cgosqlite/cgosqlite.go
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Original file line number Diff line number Diff line change
Expand Up @@ -222,7 +222,11 @@ func (stmt *Stmt) SQL() string {
}

func (stmt *Stmt) ExpandedSQL() string {
return C.GoString(C.sqlite3_expanded_sql(stmt.stmt.ptr()))
// sqlite3_expanded_sql returns a string obtained by sqlite3_malloc, which
// must be freed after use.
cstr := C.sqlite3_expanded_sql(stmt.stmt.ptr())
defer C.sqlite3_free(unsafe.Pointer(cstr))
return C.GoString(cstr)
}

func (stmt *Stmt) Reset() error {
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29 changes: 29 additions & 0 deletions sqlite_test.go
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Expand Up @@ -1539,3 +1539,32 @@ func TestConnLogger_read_tx(t *testing.T) {
}
}
}

func TestExpandedSQL(t *testing.T) {
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@bradfitz bradfitz Nov 2, 2025

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I guess it's too tedious to make this look for leaks, eh?

(probably not visible to https://pkg.go.dev/runtime#ReadMemStats ...)

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@alisdair alisdair Nov 2, 2025

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Yeah, just too fiddly for me on a Sunday morning. I would like to try it tomorrow though.

ctx := context.Background()
connector := Connector("file:"+t.TempDir()+"/test.db", nil, nil)
sqlConn, err := connector.Connect(ctx)
if err != nil {
t.Fatalf("Connect: %v", err)
}
conn := sqlConn.(*conn)

sqlStmt, err := conn.PrepareContext(ctx, "SELECT ? + ?")
if err != nil {
t.Fatalf("PrepareContext: %v", err)
}
stmt, ok := sqlStmt.(*stmt)
if !ok {
t.Fatalf("not a *stmt: %#v", stmt)
}
if err := stmt.bindAll([]driver.NamedValue{
{Ordinal: 1, Value: 6},
{Ordinal: 2, Value: 7},
}); err != nil {
t.Errorf("bindAll: %v", err)
}

if got, want := stmt.stmt.ExpandedSQL(), "SELECT 6 + 7"; got != want {
t.Errorf("wrong sql: got %q, want %q", got, want)
}
}
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