Protect against NPEs in notifications list (#10879) (#10883)

* Protect against NPEs in notifications list (#10879)

Unfortunately there appears to be potential race with notifications
being set before the associated issue has been committed.

This PR adds protection in to the notifications list to log any failures
and remove these notifications from the display.

References #10815 - and prevents the panic but does not completely fix
this.

Signed-off-by: Andrew Thornton <art27@cantab.net>

* add log import

* Update models/notification.go

Co-Authored-By: Lauris BH <lauris@nix.lv>

Co-authored-by: Lauris BH <lauris@nix.lv>

2 files changed, 76 insertions, 22 deletions

diff --git a/models/notification.go b/models/notification.go
index 5c03b49257..6c8129f88b 100644
--- a/models/notification.go
+++ b/models/notification.go
@@ -7,6 +7,7 @@ package models
 import (
 	"fmt"
 
+	"code.gitea.io/gitea/modules/log"
 	"code.gitea.io/gitea/modules/timeutil"
 )
 
@@ -281,9 +282,9 @@ func (nl NotificationList) getPendingRepoIDs() []int64 {
 }
 
 // LoadRepos loads repositories from database
-func (nl NotificationList) LoadRepos() (RepositoryList, error) {
+func (nl NotificationList) LoadRepos() (RepositoryList, []int, error) {
 	if len(nl) == 0 {
-		return RepositoryList{}, nil
+		return RepositoryList{}, []int{}, nil
 	}
 
 	var repoIDs = nl.getPendingRepoIDs()
@@ -298,7 +299,7 @@ func (nl NotificationList) LoadRepos() (RepositoryList, error) {
 			In("id", repoIDs[:limit]).
 			Rows(new(Repository))
 		if err != nil {
-			return nil, err
+			return nil, nil, err
 		}
 
 		for rows.Next() {
@@ -306,7 +307,7 @@ func (nl NotificationList) LoadRepos() (RepositoryList, error) {
 			err = rows.Scan(&repo)
 			if err != nil {
 				rows.Close()
-				return nil, err
+				return nil, nil, err
 			}
 
 			repos[repo.ID] = &repo
@@ -317,14 +318,21 @@ func (nl NotificationList) LoadRepos() (RepositoryList, error) {
 		repoIDs = repoIDs[limit:]
 	}
 
+	failed := []int{}
+
 	var reposList = make(RepositoryList, 0, len(repoIDs))
-	for _, notification := range nl {
+	for i, notification := range nl {
 		if notification.Repository == nil {
 			notification.Repository = repos[notification.RepoID]
 		}
+		if notification.Repository == nil {
+			log.Error("Notification[%d]: RepoID: %d not found", notification.ID, notification.RepoID)
+			failed = append(failed, i)
+			continue
+		}
 		var found bool
 		for _, r := range reposList {
-			if r.ID == notification.Repository.ID {
+			if r.ID == notification.RepoID {
 				found = true
 				break
 			}
@@ -333,7 +341,7 @@ func (nl NotificationList) LoadRepos() (RepositoryList, error) {
 			reposList = append(reposList, notification.Repository)
 		}
 	}
-	return reposList, nil
+	return reposList, failed, nil
 }
 
 func (nl NotificationList) getPendingIssueIDs() []int64 {
@@ -350,9 +358,9 @@ func (nl NotificationList) getPendingIssueIDs() []int64 {
 }
 
 // LoadIssues loads issues from database
-func (nl NotificationList) LoadIssues() error {
+func (nl NotificationList) LoadIssues() ([]int, error) {
 	if len(nl) == 0 {
-		return nil
+		return []int{}, nil
 	}
 
 	var issueIDs = nl.getPendingIssueIDs()
@@ -367,7 +375,7 @@ func (nl NotificationList) LoadIssues() error {
 			In("id", issueIDs[:limit]).
 			Rows(new(Issue))
 		if err != nil {
-			return err
+			return nil, err
 		}
 
 		for rows.Next() {
@@ -375,7 +383,7 @@ func (nl NotificationList) LoadIssues() error {
 			err = rows.Scan(&issue)
 			if err != nil {
 				rows.Close()
-				return err
+				return nil, err
 			}
 
 			issues[issue.ID] = &issue
@@ -386,13 +394,38 @@ func (nl NotificationList) LoadIssues() error {
 		issueIDs = issueIDs[limit:]
 	}
 
-	for _, notification := range nl {
+	failures := []int{}
+
+	for i, notification := range nl {
 		if notification.Issue == nil {
 			notification.Issue = issues[notification.IssueID]
+			if notification.Issue == nil {
+				log.Error("Notification[%d]: IssueID: %d Not Found", notification.ID, notification.IssueID)
+				failures = append(failures, i)
+				continue
+			}
 			notification.Issue.Repo = notification.Repository
 		}
 	}
-	return nil
+	return failures, nil
+}
+
+// Without returns the notification list without the failures
+func (nl NotificationList) Without(failures []int) NotificationList {
+	if len(failures) == 0 {
+		return nl
+	}
+	remaining := make([]*Notification, 0, len(nl))
+	last := -1
+	var i int
+	for _, i = range failures {
+		remaining = append(remaining, nl[last+1:i]...)
+		last = i
+	}
+	if len(nl) > i {
+		remaining = append(remaining, nl[i+1:]...)
+	}
+	return remaining
 }
 
 func (nl NotificationList) getPendingCommentIDs() []int64 {
@@ -409,9 +442,9 @@ func (nl NotificationList) getPendingCommentIDs() []int64 {
 }
 
 // LoadComments loads comments from database
-func (nl NotificationList) LoadComments() error {
+func (nl NotificationList) LoadComments() ([]int, error) {
 	if len(nl) == 0 {
-		return nil
+		return []int{}, nil
 	}
 
 	var commentIDs = nl.getPendingCommentIDs()
@@ -426,7 +459,7 @@ func (nl NotificationList) LoadComments() error {
 			In("id", commentIDs[:limit]).
 			Rows(new(Comment))
 		if err != nil {
-			return err
+			return nil, err
 		}
 
 		for rows.Next() {
@@ -434,7 +467,7 @@ func (nl NotificationList) LoadComments() error {
 			err = rows.Scan(&comment)
 			if err != nil {
 				rows.Close()
-				return err
+				return nil, err
 			}
 
 			comments[comment.ID] = &comment
@@ -445,13 +478,19 @@ func (nl NotificationList) LoadComments() error {
 		commentIDs = commentIDs[limit:]
 	}
 
-	for _, notification := range nl {
+	failures := []int{}
+	for i, notification := range nl {
 		if notification.CommentID > 0 && notification.Comment == nil && comments[notification.CommentID] != nil {
 			notification.Comment = comments[notification.CommentID]
+			if notification.Comment == nil {
+				log.Error("Notification[%d]: CommentID[%d] failed to load", notification.ID, notification.CommentID)
+				failures = append(failures, i)
+				continue
+			}
 			notification.Comment.Issue = notification.Issue
 		}
 	}
-	return nil
+	return failures, nil
 }
 
 // GetNotificationCount returns the notification count for user
diff --git a/routers/user/notification.go b/routers/user/notification.go
index cd6617a233..2065057ed1 100644
--- a/routers/user/notification.go
+++ b/routers/user/notification.go
@@ -68,24 +68,39 @@ func Notifications(c *context.Context) {
 		return
 	}
 
-	repos, err := notifications.LoadRepos()
+	failCount := 0
+
+	repos, failures, err := notifications.LoadRepos()
 	if err != nil {
 		c.ServerError("LoadRepos", err)
 		return
 	}
+	notifications = notifications.Without(failures)
 	if err := repos.LoadAttributes(); err != nil {
 		c.ServerError("LoadAttributes", err)
 		return
 	}
+	failCount += len(failures)
 
-	if err := notifications.LoadIssues(); err != nil {
+	failures, err = notifications.LoadIssues()
+	if err != nil {
 		c.ServerError("LoadIssues", err)
 		return
 	}
-	if err := notifications.LoadComments(); err != nil {
+	notifications = notifications.Without(failures)
+	failCount += len(failures)
+
+	failures, err = notifications.LoadComments()
+	if err != nil {
 		c.ServerError("LoadComments", err)
 		return
 	}
+	notifications = notifications.Without(failures)
+	failCount += len(failures)
+
+	if failCount > 0 {
+		c.Flash.Error(fmt.Sprintf("ERROR: %d notifications were removed due to missing parts - check the logs", failCount))
+	}
 
 	total, err := models.GetNotificationCount(c.User, status)
 	if err != nil {