add mutex on download store

pkg/vfs/download_store.go

@@ -2,6 +2,7 @@ package vfs
 
 import (
 	"encoding/hex"
+	"sync"
 	"time"
 
 	"github.com/cozy/cozy-stack/pkg/crypto"
@@ -24,6 +25,7 @@ type fileRef struct {
 const downloadStoreTTL = 1 * time.Hour
 const downloadStoreCleanInterval = 1 * time.Hour
 
+var storeStoreMutex = &sync.Mutex{}
 var storeStore map[string]*memStore
 
 func init() {
@@ -51,6 +53,8 @@ func cleanStore(s *memStore) {
 }
 
 func cleanDownloadStore() {
+	storeStoreMutex.Lock()
+	defer storeStoreMutex.Unlock()
 	for i, s := range storeStore {
 		cleanStore(s)
 		if len(s.Files) == 0 && len(s.Archives) == 0 {
@@ -61,21 +65,24 @@ func cleanDownloadStore() {
 
 // GetStore returns the DownloadStore for the given Instance
 func GetStore(domain string) DownloadStore {
+	storeStoreMutex.Lock()
+	defer storeStoreMutex.Unlock()
 	if storeStore == nil {
 		storeStore = make(map[string]*memStore)
 	}
-	store, ok := storeStore[domain]
-	if ok {
-		return store
-	}
-	storeStore[domain] = &memStore{
-		Archives: make(map[string]*Archive),
-		Files:    make(map[string]*fileRef),
+	store, exists := storeStore[domain]
+	if !exists {
+		store = &memStore{
+			Archives: make(map[string]*Archive),
+			Files:    make(map[string]*fileRef),
+		}
+		storeStore[domain] = store
 	}
-	return storeStore[domain]
+	return store
 }
 
 type memStore struct {
+	Mutex    sync.Mutex
 	Archives map[string]*Archive
 	Files    map[string]*fileRef
 }
@@ -89,6 +96,8 @@ func (s *memStore) AddFile(f string) (string, error) {
 		Path:      f,
 		ExpiresAt: time.Now().Add(downloadStoreTTL),
 	}
+	s.Mutex.Lock()
+	defer s.Mutex.Unlock()
 	cleanStore(s)
 	key := s.makeSecret()
 	s.Files[key] = fref
@@ -97,13 +106,17 @@ func (s *memStore) AddFile(f string) (string, error) {
 
 func (s *memStore) AddArchive(a *Archive) (string, error) {
 	a.ExpiresAt = time.Now().Add(downloadStoreTTL)
+	s.Mutex.Lock()
+	defer s.Mutex.Unlock()
 	cleanStore(s)
 	key := s.makeSecret()
 	s.Archives[key] = a
 	return key, nil
 }
 
 func (s *memStore) GetFile(k string) (string, error) {
+	s.Mutex.Lock()
+	defer s.Mutex.Unlock()
 	f, ok := s.Files[k]
 	if !ok {
 		return "", nil
@@ -116,6 +129,8 @@ func (s *memStore) GetFile(k string) (string, error) {
 }
 
 func (s *memStore) GetArchive(k string) (*Archive, error) {
+	s.Mutex.Lock()
+	defer s.Mutex.Unlock()
 	a, ok := s.Archives[k]
 	if !ok {
 		return nil, nil