Possible "index out of range" in `equalMarks`
Antonboom opened this issue · comments
Hello!
I'm interested in carefree iteration over lists whose lengths can vary:
// equalMarks compares two error markers.
func equalMarks(m1, m2 errorMark) bool {
if m1.msg != m2.msg {
return false
}
for i, t := range m1.types {
if !t.Equals(m2.types[i]) {
return false
}
}
return true
}
And I made an example that breaks this code:
package main
import (
"fmt"
"github.com/cockroachdb/errors"
)
type SimpleWrapper struct {
err error
}
func (w SimpleWrapper) Error() string {
return "boom!"
}
func (w SimpleWrapper) Unwrap() error {
return w.err
}
func main() {
stack := errors.WithStack
ref := stack(stack(SimpleWrapper{}))
err := stack(stack(SimpleWrapper{err: stack(errors.New("boom!"))}))
if errors.IsAny(err, ref) {
fmt.Println("gotcha!")
}
/* panic: runtime error: index out of range [3] with length 3
goroutine 1 [running]:
github.com/cockroachdb/errors/markers.equalMarks(...)
github.com/cockroachdb/errors@v1.9.0/markers/markers.go:205
github.com/cockroachdb/errors/markers.IsAny({0x102802528, 0x1400000e438}, {0x14000167f48, 0x1, 0x14000167f28?})
github.com/cockroachdb/errors@v1.9.0/markers/markers.go:186 +0x364
github.com/cockroachdb/errors.IsAny(...)
github.com/cockroachdb/errors@v1.9.0/markers_api.go:64
main.main()
examples/04-non-standard-modules/cockroach-is-any-bug/main.go:26 +0x318
*/
}
Where am I wrong?
Hi, I believe part of the problem is that the ref
error has an incomplete SimpleWrapper instance ( its err
field is nil), which will mess up the type mark.
Does the error persist if you add a proper err
to your SimpleWrapper reference?
In any case, I agree the ergonomics are not ideal, so perhaps there's something to improve here.
Does the error persist if you add a proper err to your SimpleWrapper reference?
No, now you won't break it quickly :)
You can close the issue, I don't mind, just expressed doubt.
Maybe add an explicit check for the lengths of ref lists?