fix: address potential crash that can happen with queued object storage uploads. Fixes #3440

core/storageproviders/s3Storage.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 	"sort"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/owncast/owncast/core/data"
@@ -26,26 +27,29 @@ import (
 
 // S3Storage is the s3 implementation of a storage provider.
 type S3Storage struct {
-	sess     *session.Session
+	// If we try to upload a playlist but it is not yet on disk
+	// then keep a reference to it here.
+	queuedPlaylistUpdates map[string]string
+
 	s3Client *s3.S3
 
 	uploader *s3manager.Uploader
 
-	// If we try to upload a playlist but it is not yet on disk
-	// then keep a reference to it here.
-	queuedPlaylistUpdates map[string]string
+	sess     *session.Session
+	s3Secret string
 
 	s3Bucket          string
 	s3Region          string
 	s3ServingEndpoint string
 	s3AccessKey       string
-	s3Secret          string
 	s3ACL             string
 	s3PathPrefix      string
 
 	s3Endpoint string
 	host       string
 
+	lock sync.Mutex
+
 	s3ForcePathStyle bool
 }
 
@@ -53,6 +57,7 @@ type S3Storage struct {
 func NewS3Storage() *S3Storage {
 	return &S3Storage{
 		queuedPlaylistUpdates: make(map[string]string),
+		lock:                  sync.Mutex{},
 	}
 }
 
@@ -126,6 +131,8 @@ func (s *S3Storage) VariantPlaylistWritten(localFilePath string) {
 	// We are uploading the variant playlist after uploading the segment
 	// to make sure we're not referring to files in a playlist that don't
 	// yet exist.  See SegmentWritten.
+	s.lock.Lock()
+	defer s.lock.Unlock()
 	if _, ok := s.queuedPlaylistUpdates[localFilePath]; ok {
 		if _, err := s.Save(localFilePath, 0); err != nil {
 			log.Errorln(err)