Merge pull request #150 from tri-adam/launch-script

Add OptCreateWithLaunchScript

internal/app/siftool/info.go

@@ -39,7 +39,9 @@ func readableSize(size int64) string {
 func writeHeader(w io.Writer, f *sif.FileImage) error {
 	tw := tabwriter.NewWriter(w, 0, 0, 0, ' ', 0)
 
-	fmt.Fprintln(tw, "Launch Script:\t", strings.TrimSuffix(f.LaunchScript(), "\n"))
+	if s := f.LaunchScript(); s != "" {
+		fmt.Fprintln(tw, "Launch Script:\t", strings.TrimSuffix(s, "\n"))
+	}
 	fmt.Fprintln(tw, "Version:\t", f.Version())
 	fmt.Fprintln(tw, "Primary Architecture:\t", f.PrimaryArch())
 	fmt.Fprintln(tw, "ID:\t", f.ID())

pkg/sif/create.go

@@ -115,6 +115,7 @@ func (f *FileImage) writeHeader() error {
 
 // createOpts accumulates container creation options.
 type createOpts struct {
+	launchScript       [hdrLaunchLen]byte
 	id                 uuid.UUID
 	descriptorsOffset  int64
 	descriptorCapacity int64
@@ -126,6 +127,23 @@ type createOpts struct {
 // CreateOpt are used to specify container creation options.
 type CreateOpt func(*createOpts) error
 
+var errLaunchScriptLen = errors.New("launch script too large")
+
+// OptCreateWithLaunchScript specifies s as the launch script.
+func OptCreateWithLaunchScript(s string) CreateOpt {
+	return func(co *createOpts) error {
+		b := []byte(s)
+
+		if len(b) >= len(co.launchScript) {
+			return errLaunchScriptLen
+		}
+
+		copy(co.launchScript[:], b)
+
+		return nil
+	}
+}
+
 // OptCreateWithID specifies id as the unique ID.
 func OptCreateWithID(id string) CreateOpt {
 	return func(co *createOpts) error {
@@ -175,6 +193,7 @@ func createContainer(rw ReadWriter, co createOpts) (*FileImage, error) {
 	rdsSize := int64(binary.Size(rds))
 
 	h := header{
+		LaunchScript:      co.launchScript,
 		Arch:              hdrArchUnknown,
 		ID:                co.id,
 		CreatedAt:         co.t.Unix(),
@@ -185,7 +204,6 @@ func createContainer(rw ReadWriter, co createOpts) (*FileImage, error) {
 		DescriptorsSize:   rdsSize,
 		DataOffset:        co.descriptorsOffset + rdsSize,
 	}
-	copy(h.LaunchScript[:], hdrLaunch)
 	copy(h.Magic[:], hdrMagic)
 	copy(h.Version[:], CurrentVersion.bytes())
 
@@ -221,6 +239,8 @@ func createContainer(rw ReadWriter, co createOpts) (*FileImage, error) {
 //
 // By default, the image will support a maximum of 48 descriptors. To change this, consider using
 // OptCreateWithDescriptorCapacity.
+//
+// A launch script can optionally be set using OptCreateWithLaunchScript.
 func CreateContainer(rw ReadWriter, opts ...CreateOpt) (*FileImage, error) {
 	id, err := uuid.NewRandom()
 	if err != nil {
@@ -257,6 +277,8 @@ func CreateContainer(rw ReadWriter, opts ...CreateOpt) (*FileImage, error) {
 //
 // By default, the image will support a maximum of 48 descriptors. To change this, consider using
 // OptCreateWithDescriptorCapacity.
+//
+// A launch script can optionally be set using OptCreateWithLaunchScript.
 func CreateContainerAtPath(path string, opts ...CreateOpt) (*FileImage, error) {
 	fp, err := os.OpenFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0o755)
 	if err != nil {

pkg/sif/create_test.go

@@ -50,6 +50,14 @@ func TestCreateContainer(t *testing.T) {
 				OptCreateWithTime(testTime),
 			},
 		},
+		{
+			name: "LaunchScript",
+			opts: []CreateOpt{
+				OptCreateWithID(testID),
+				OptCreateWithTime(testTime),
+				OptCreateWithLaunchScript("#!/usr/bin/env launch-script\n"),
+			},
+		},
 		{
 			name: "EmptyCloseOnUnload",
 			opts: []CreateOpt{

pkg/sif/sif.go

@@ -86,7 +86,6 @@ import (
 
 // SIF header constants and quantities.
 const (
-	hdrLaunch     = "#!/usr/bin/env run-singularity\n"
 	hdrLaunchLen  = 32 // len("#!/usr/bin/env... ")
 	hdrMagic      = "SIF_MAGIC"
 	hdrMagicLen   = 10 // len("SIF_MAGIC")

pkg/sif/sif_test.go

@@ -23,7 +23,7 @@ func TestHeader_GetIntegrityReader(t *testing.T) {
 		CreatedAt:  1504657553,
 		ModifiedAt: 1504657653,
 	}
-	copy(h.LaunchScript[:], hdrLaunch)
+	copy(h.LaunchScript[:], "#!/usr/bin/env run-singularity\n")
 	copy(h.Magic[:], hdrMagic)
 	copy(h.Version[:], CurrentVersion.bytes())
 

test/gen_sifs.go

@@ -162,6 +162,7 @@ func generateImages() error {
 			sif.OptCreateWithID(image.id),
 			sif.OptCreateWithTime(image.createdAt),
 			sif.OptCreateWithDescriptors(dis...),
+			sif.OptCreateWithLaunchScript("#!/usr/bin/env run-singularity\n"),
 		)
 		if err != nil {
 			return err