Check error when creating local storage directory

When we have an error creating the local storage directory, such as if
the permissions are wrong, we fail to produce a helpful error message,
since we fail to check the error we produce.

Let's take the error we get in such a case and pass it through to the
transfer queue, where we can handle it as any other error.  This means
that if only one directory has a problem, we can transfer the rest of
the objects and fail for only the one problematic object.

commands/command_migrate_export.go

@@ -136,7 +136,7 @@ func migrateExportCommand(cmd *cobra.Command, args []string) {
 			}
 
 			if _, err := os.Stat(downloadPath); os.IsNotExist(err) {
-				q.Add(p.Name, downloadPath, p.Oid, p.Size, false)
+				q.Add(p.Name, downloadPath, p.Oid, p.Size, false, nil)
 			}
 		})
 		gs.ScanRefs(opts.Include, opts.Exclude, nil)

commands/command_smudge.go

@@ -59,7 +59,7 @@ func delayedSmudge(gf *lfs.GitFilter, s *git.FilterProcessScanner, to io.Writer,
 
 	if !skip && filter.Allows(filename) {
 		if _, statErr := os.Stat(path); statErr != nil {
-			q.Add(filename, path, ptr.Oid, ptr.Size, false)
+			q.Add(filename, path, ptr.Oid, ptr.Size, false, err)
 			return 0, true, ptr, nil
 		}
 

commands/commands.go

@@ -131,9 +131,9 @@ func buildFilepathFilter(config *config.Configuration, includeArg, excludeArg *s
 	return filepathfilter.New(inc, exc)
 }
 
-func downloadTransfer(p *lfs.WrappedPointer) (name, path, oid string, size int64, missing bool) {
-	path, _ = cfg.Filesystem().ObjectPath(p.Oid)
-	return p.Name, path, p.Oid, p.Size, false
+func downloadTransfer(p *lfs.WrappedPointer) (name, path, oid string, size int64, missing bool, err error) {
+	path, err = cfg.Filesystem().ObjectPath(p.Oid)
+	return p.Name, path, p.Oid, p.Size, false, err
 }
 
 // Get user-readable manual install steps for hooks

commands/uploader.go

@@ -258,7 +258,7 @@ func (c *uploadContext) UploadPointers(q *tq.TransferQueue, unfiltered ...*lfs.W
 			ExitWithError(err)
 		}
 
-		q.Add(t.Name, t.Path, t.Oid, t.Size, t.Missing)
+		q.Add(t.Name, t.Path, t.Oid, t.Size, t.Missing, nil)
 		c.SetUploaded(p.Oid)
 	}
 }

lfs/gitfilter_smudge.go

@@ -101,7 +101,7 @@ func (f *GitFilter) downloadFile(writer io.Writer, ptr *Pointer, workingfile, me
 		tq.WithProgressCallback(cb),
 		tq.RemoteRef(f.RemoteRef()),
 	)
-	q.Add(filepath.Base(workingfile), mediafile, ptr.Oid, ptr.Size, false)
+	q.Add(filepath.Base(workingfile), mediafile, ptr.Oid, ptr.Size, false, nil)
 	q.Wait()
 
 	if errs := q.Errors(); len(errs) > 0 {

t/git-lfs-test-server-api/main.go

@@ -206,7 +206,7 @@ func buildTestData(repo *t.Repo, manifest *tq.Manifest) (oidsExist, oidsMissing
 		if err != nil {
 			return nil, nil, err
 		}
-		uploadQueue.Add(t.Name, t.Path, t.Oid, t.Size, false)
+		uploadQueue.Add(t.Name, t.Path, t.Oid, t.Size, false, nil)
 	}
 	uploadQueue.Wait()
 

t/t-fetch.sh

@@ -619,3 +619,23 @@ begin_test "fetch with invalid remote"
   grep "Invalid remote name" fetch.log
 )
 end_test
+
+begin_test "fetch fails when LFS directory has wrong permissions"
+(
+  set -e
+
+  # Windows lacks POSIX permissions.
+  [ "$IS_WINDOWS" -eq 1 ] && exit 0
+
+  # Root is exempt from permissions.
+  [ "$(id -u)" -eq 0 ] && exit 0
+
+  cd shared
+  rm -rf .git/lfs/objects
+  mkdir .git/lfs/objects
+  chmod 400 .git/lfs/objects
+
+  git lfs fetch 2>&1 | tee fetch.log
+  grep "error trying to create local storage directory" fetch.log
+)
+end_test

tq/transfer_queue.go

@@ -324,7 +324,12 @@ func NewTransferQueue(dir Direction, manifest *Manifest, remote string, options
 //
 // Only one file will be transferred to/from the Path element of the first
 // transfer.
-func (q *TransferQueue) Add(name, path, oid string, size int64, missing bool) {
+func (q *TransferQueue) Add(name, path, oid string, size int64, missing bool, err error) {
+	if err != nil {
+		q.errorc <- err
+		return
+	}
+
 	t := &objectTuple{
 		Name:    name,
 		Path:    path,