Skip to content

Fix error when applying upperdir tar snapshot containing empty files #12229

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Oct 17, 2025
Merged

Fix error when applying upperdir tar snapshot containing empty files #12229

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 3 additions & 1 deletion pkg/sentry/fsimpl/tmpfs/tar.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -77,8 +77,10 @@ func (fs *filesystem) readFromTar(ctx context.Context, tr *tar.Reader) error {
if n != header.Size {
return fmt.Errorf("failed to read all file content, got %d bytes, want %d", n, header.Size)
}
if header.Size > 0 {
fileToContent[header.Name] = &buffer
}
fileToHeader[header.Name] = header
fileToContent[header.Name] = &buffer
case tar.TypeFifo, tar.TypeBlock, tar.TypeChar:
fileToHeader[header.Name] = header
case tar.TypeSymlink:
Expand Down
3 changes: 1 addition & 2 deletions runsc/container/container_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4035,11 +4035,10 @@ func TestTarRootfsUpperLayer(t *testing.T) {
if err := cont.Start(conf); err != nil {
t.Fatalf("error starting container: %v", err)
}

// Exec the command in the container.
execArgs := &control.ExecArgs{
Filename: app,
Argv: []string{app, "fsTreeCreate", "--depth=3", "--file-per-level=2", "--file-size=1470", "--create-symlink"},
Argv: []string{app, "fsTreeCreate", "--depth=3", "--file-per-level=2", "--file-size=1470", "--create-symlink", "--add-empty-files"},
}
if ws, err := cont.executeSync(conf, execArgs); err != nil {
t.Fatalf("error exec'ing: %v", err)
Expand Down
8 changes: 8 additions & 0 deletions test/cmd/test_app/main.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -67,6 +67,7 @@ type fsTreeCreator struct {
fileSize uint
targetDir string
createSymlink bool
addEmptyFiles bool
}

// Name implements subcommands.Command.Name.
Expand All @@ -91,6 +92,7 @@ func (c *fsTreeCreator) SetFlags(f *flag.FlagSet) {
f.UintVar(&c.fileSize, "file-size", 4096, "size of each file")
f.StringVar(&c.targetDir, "target-dir", "/", "directory under which to create the filesystem tree")
f.BoolVar(&c.createSymlink, "create-symlink", false, "create symlinks other than the first file per level")
f.BoolVar(&c.addEmptyFiles, "add-empty-files", false, "add empty file to each level")
}

// Execute implements subcommands.Command.Execute.
Expand All @@ -117,6 +119,12 @@ func (c *fsTreeCreator) Execute(ctx context.Context, f *flag.FlagSet, args ...an
}
}
}
if c.addEmptyFiles {
emptyPath := filepath.Join(curDir, fmt.Sprintf("empty%d", i))
if err := os.WriteFile(emptyPath, nil, 0666); err != nil {
log.Fatalf("error writing empty file %q: %v", emptyPath, err)
}
}
nextDir := filepath.Join(curDir, "dir")
if err := os.Mkdir(nextDir, 0777); err != nil {
log.Fatalf("error creating directory %q: %v", nextDir, err)
Expand Down