// BuildSquashfsSnap the given sourceDirectory and return the generated
// snap file
func BuildSquashfsSnap(sourceDir, targetDir string) (string, error) {
// create build dir
buildDir, err := ioutil.TempDir("", "snappy-build-")
if err != nil {
return "", err
}
defer os.RemoveAll(buildDir)
snapName, err := prepare(sourceDir, targetDir, buildDir)
if err != nil {
return "", err
}
d := squashfs.New(snapName)
if err = d.Build(buildDir); err != nil {
return "", err
}
return snapName, nil
}
// Open opens a given snap file with the right backend
func Open(path string) (File, error) {
f, err := os.Open(path)
if err != nil {
return nil, fmt.Errorf("cannot open snap: %v", err)
}
defer f.Close()
// look, libmagic!
header := make([]byte, 20)
if _, err := f.ReadAt(header, 0); err != nil {
return nil, fmt.Errorf("cannot read snap: %v", err)
}
// Note that we only support little endian squashfs. There
// is nothing else with squashfs 4.0.
if bytes.HasPrefix(header, []byte{'h', 's', 'q', 's'}) {
return squashfs.New(path), nil
}
if strings.HasPrefix(string(header), "!<arch>\ndebian") {
return clickdeb.Open(path)
}
return nil, fmt.Errorf("cannot open snap: unknown header: %q", header)
}