Fixes a notes data-loss bug where purgeAllSteps(fileID) ignored its fileID (#4712)

 ## Summary

This fixes a notes data-loss bug where purgeAllSteps(fileID) ignored its
fileID argument and deleted step documents for all notes in
io.cozy.notes.steps, not only the targeted note.


##  Bug story

We investigated a production incident where a user lost note content
after a reload.
- On Tuesday, the note 019d1f37-b201-7d8a-901d-39922cf7c647 accumulated
a large number of unsaved note steps.
- On Wednesday, Couch/stack logs showed a BulkDeleteDocs for
io.cozy.notes.steps batch containing step IDs from multiple different
notes.
- In the stack code, purgeAllSteps(inst, fileID) was supposed to clear
steps for one note after a schema update or .cozy-note overwrite/import.
- But the implementation iterated the whole io.cozy.notes.steps database
and deleted every step doc it found, regardless of fileID.

This means that an action on note B could wipe unsaved steps for note A.

The most likely production trigger is: overwrite/import of another
existing .cozy-note file

Author: shepilov

model/note/step.go

@@ -3,6 +3,7 @@ package note
 import (
 	"encoding/json"
 	"fmt"
+	"strings"
 	"time"
 
 	"github.com/cozy/cozy-stack/model/instance"
@@ -255,11 +256,15 @@ func purgeOldSteps(inst *instance.Instance, fileID string) {
 
 func purgeAllSteps(inst *instance.Instance, fileID string) {
 	var docs []couchdb.Doc
+	prefix := startkey(fileID)
 	err := couchdb.ForeachDocsWithCustomPagination(inst, consts.NotesSteps, 1000, func(_ string, raw json.RawMessage) error {
 		var doc Step
 		if err := json.Unmarshal(raw, &doc); err != nil {
 			return err
 		}
+		if !strings.HasPrefix(doc.ID(), prefix) {
+			return nil
+		}
 		docs = append(docs, doc)
 		return nil
 	})

web/data/data_test.go

@@ -5,10 +5,12 @@ import (
 	"fmt"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/cozy/cozy-stack/model/instance"
 	"github.com/cozy/cozy-stack/pkg/config/config"
 	"github.com/cozy/cozy-stack/pkg/couchdb"
+	"github.com/cozy/cozy-stack/pkg/couchdb/mango"
 	"github.com/cozy/cozy-stack/tests/testutils"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -443,16 +445,25 @@ func TestData(t *testing.T) {
 		_ = getDocForTest(Type, testInstance)
 		_ = getDocForTest(Type, testInstance)
 
-		// Create the index
-		e.POST("/data/"+Type+"/_index").
+		// Create and wait for the index used by the selector.
+		indexName := e.POST("/data/"+Type+"/_index").
 			WithHeader("Authorization", "Bearer "+token).
 			WithHeader("Content-Type", "application/json").
 			WithBytes([]byte(`{ "index": { "fields": ["test"] } }`)).
 			Expect().Status(200).
 			JSON().Object().
-			NotContainsKey("error")
+			NotContainsKey("error").
+			Value("name").String().Raw()
+
+		require.Eventually(t, func() bool {
+			var results []couchdb.JSONDoc
+			err := couchdb.FindDocs(testInstance, Type, &couchdb.FindRequest{
+				Selector: mango.Equal("test", "value"),
+				UseIndex: indexName,
+			}, &results)
+			return err == nil
+		}, 5*time.Second, 100*time.Millisecond, "index %q should be ready within 5s", indexName)
 
-		// Select with the index
 		obj := e.POST("/data/"+Type+"/_find").
 			WithHeader("Authorization", "Bearer "+token).
 			WithHeader("Content-Type", "application/json").
@@ -472,13 +483,25 @@ func TestData(t *testing.T) {
 		_ = getDocForTest(Type, testInstance)
 
 		// Create the index
-		e.POST("/data/"+Type+"/_index").
+		indexName := e.POST("/data/"+Type+"/_index").
 			WithHeader("Authorization", "Bearer "+token).
 			WithHeader("Content-Type", "application/json").
 			WithBytes([]byte(`{ "index": { "fields": ["test"] } }`)).
 			Expect().Status(200).
 			JSON().Object().
-			NotContainsKey("error")
+			NotContainsKey("error").
+			Value("name").String().Raw()
+
+		// CouchDB builds indexes asynchronously. Wait until the index is ready
+		// to serve queries before asserting on execution_stats.
+		require.Eventually(t, func() bool {
+			var results []couchdb.JSONDoc
+			err := couchdb.FindDocs(testInstance, Type, &couchdb.FindRequest{
+				Selector: mango.Equal("test", "value"),
+				UseIndex: indexName,
+			}, &results)
+			return err == nil
+		}, 5*time.Second, 100*time.Millisecond, "index %q should be ready within 5s", indexName)
 
 		// Select with the index
 		e.POST("/data/"+Type+"/_find").

web/notes/notes_test.go

@@ -500,6 +500,53 @@ func TestNotes(t *testing.T) {
 		version = int64(obj.Path("$.data.attributes.metadata.version").Number().Raw())
 	})
 
+	t.Run("PutSchema only purges steps for the updated note", func(t *testing.T) {
+		schemaNote, err := note.Create(inst, &note.Document{
+			Title:      "Schema note",
+			SchemaSpec: note.DefaultSchemaSpecs(),
+		})
+		require.NoError(t, err)
+
+		stepsNote, err := note.Create(inst, &note.Document{
+			Title:      "Steps note",
+			SchemaSpec: note.DefaultSchemaSpecs(),
+		})
+		require.NoError(t, err)
+
+		stepsFile, err := inst.VFS().FileByID(stepsNote.ID())
+		require.NoError(t, err)
+
+		steps := []note.Step{{
+			"sessionID": "regression",
+			"stepType":  "replace",
+			"from":      1,
+			"to":        1,
+			"slice": map[string]interface{}{
+				"content": []interface{}{
+					map[string]interface{}{"type": "text", "text": "A"},
+				},
+			},
+		}}
+		_, err = note.ApplySteps(inst, stepsFile, "0", steps)
+		require.NoError(t, err)
+
+		existing, err := note.GetSteps(inst, stepsNote.ID(), 0)
+		require.NoError(t, err)
+		require.Len(t, existing, 1)
+
+		schemaFile, err := inst.VFS().FileByID(schemaNote.ID())
+		require.NoError(t, err)
+
+		_, err = note.UpdateSchema(inst, schemaFile, note.DefaultSchemaSpecs())
+		require.NoError(t, err)
+
+		time.Sleep(1 * time.Second)
+
+		remaining, err := note.GetSteps(inst, stepsNote.ID(), 0)
+		require.NoError(t, err)
+		require.Len(t, remaining, 1)
+	})
+
 	t.Run("PutTelepointer", func(t *testing.T) {
 		e := testutils.CreateTestClient(t, ts.URL)