Merge pull request #11631 from vegaprotocol/hotfix-cumulated-err-recu…

…rsion

fix: check for circular references

libs/errors/errors.go

@@ -15,7 +15,15 @@
 
 package errors
 
-import "strings"
+import (
+	"fmt"
+	"strings"
+)
+
+var (
+	errSelfReference   = fmt.Errorf("<self reference>")
+	errParentReference = fmt.Errorf("<parent reference>")
+)
 
 type CumulatedErrors struct {
 	Errors []error
@@ -26,9 +34,41 @@ func NewCumulatedErrors() *CumulatedErrors {
 }
 
 func (e *CumulatedErrors) Add(err error) {
+	// prevent adding this instance of cumulatedErrors to itself.
+	if err == e {
+		err = errSelfReference
+	} else if cerr, ok := err.(*CumulatedErrors); ok {
+		// nothing to add.
+		if !cerr.HasAny() {
+			return
+		}
+		// create a copy of the error we're adding
+		cpy := &CumulatedErrors{
+			Errors: append([]error{}, cerr.Errors...),
+		}
+		// remove any references to the parent from the error we're adding.
+		err = cpy.checkRef(e, errParentReference)
+	}
 	e.Errors = append(e.Errors, err)
 }
 
+// check recursively if a cumulated errors object contains a certain reference, and if so, replace with a placehold, simple error.
+// returns either itself (with the replaced references), or a replacement error.
+func (e *CumulatedErrors) checkRef(ref *CumulatedErrors, repl error) error {
+	if e == ref {
+		return repl
+	}
+	// recursively remove a given reference.
+	for i, subE := range e.Errors {
+		if subE == ref {
+			e.Errors[i] = repl
+		} else if cErr, ok := subE.(*CumulatedErrors); ok {
+			e.Errors[i] = cErr.checkRef(ref, repl)
+		}
+	}
+	return e
+}
+
 func (e *CumulatedErrors) HasAny() bool {
 	return len(e.Errors) > 0
 }

libs/errors/errors_test.go

@@ -0,0 +1,69 @@
+// Copyright (C) 2023 Gobalsky Labs Limited
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as
+// published by the Free Software Foundation, either version 3 of the
+// License, or (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package errors_test
+
+import (
+	"fmt"
+	"testing"
+
+	"code.vegaprotocol.io/vega/libs/errors"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestCircularreferences(t *testing.T) {
+	parent := errors.NewCumulatedErrors()
+	child := errors.NewCumulatedErrors()
+	nested := errors.NewCumulatedErrors()
+	errs := []error{
+		fmt.Errorf("simple error 1"),
+		fmt.Errorf("simple error 2"),
+		fmt.Errorf("simple error 3"),
+	}
+	t.Run("try to add parent to itself", func(t *testing.T) {
+		parent.Add(parent)
+		expect := "<self reference>"
+		require.True(t, parent.HasAny())
+		require.Equal(t, expect, parent.Error())
+	})
+	t.Run("try nesting without circular references", func(t *testing.T) {
+		child.Add(errs[0])
+		parent.Add(child)
+		expect := fmt.Sprintf("<self reference>, also %s", errs[0].Error())
+		require.Equal(t, expect, parent.Error())
+	})
+	t.Run("try adding empty cumulated error", func(t *testing.T) {
+		parent.Add(nested)
+		// still the same expected value
+		expect := fmt.Sprintf("<self reference>, also %s", errs[0].Error())
+		require.False(t, nested.HasAny())
+		require.Equal(t, expect, parent.Error())
+		// adding to the nested error should not affect the parent.
+		nested.Add(errs[1])
+		require.True(t, nested.HasAny())
+		require.Equal(t, expect, parent.Error())
+	})
+	t.Run("try nesting both parent and child, and adding to both", func(t *testing.T) {
+		nested.Add(errs[2])
+		nested.Add(child)
+		nested.Add(parent)
+		child.Add(nested)
+		parent.Add(nested)
+		// self reference>, also simple error 1, also simple error 2, also simple error 3, also simple error 1, also <self reference>, also simple error 1
+		expect := fmt.Sprintf("<self reference>, also %s, also %s, also %s, also %s, also <self reference>, also %s", errs[0].Error(), errs[1].Error(), errs[2].Error(), errs[0].Error(), errs[0].Error())
+		require.Equal(t, expect, parent.Error())
+	})
+}