Refactor repository layout and convert build system to Mage.

This commit implements a massive refactor of the repository, and
moves the build system over to use Mage (magefile.org) which should
allow seamless building across multiple platforms.

vendor/github.com/mholt/archiver/tarbz2.go

@@ -0,0 +1,106 @@
+package archiver
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	"github.com/dsnet/compress/bzip2"
+)
+
+// TarBz2 is for TarBz2 format
+var TarBz2 tarBz2Format
+
+func init() {
+	RegisterFormat("TarBz2", TarBz2)
+}
+
+type tarBz2Format struct{}
+
+func (tarBz2Format) Match(filename string) bool {
+	return strings.HasSuffix(strings.ToLower(filename), ".tar.bz2") ||
+		strings.HasSuffix(strings.ToLower(filename), ".tbz2") ||
+		isTarBz2(filename)
+}
+
+// isTarBz2 checks the file has the bzip2 compressed Tar format header by
+// reading its beginning block.
+func isTarBz2(tarbz2Path string) bool {
+	f, err := os.Open(tarbz2Path)
+	if err != nil {
+		return false
+	}
+	defer f.Close()
+
+	bz2r, err := bzip2.NewReader(f, nil)
+	if err != nil {
+		return false
+	}
+	defer bz2r.Close()
+
+	buf := make([]byte, tarBlockSize)
+	n, err := bz2r.Read(buf)
+	if err != nil || n < tarBlockSize {
+		return false
+	}
+
+	return hasTarHeader(buf)
+}
+
+// Write outputs a .tar.bz2 file to a Writer containing
+// the contents of files listed in filePaths. File paths
+// can be those of regular files or directories. Regular
+// files are stored at the 'root' of the archive, and
+// directories are recursively added.
+func (tarBz2Format) Write(output io.Writer, filePaths []string) error {
+	return writeTarBz2(filePaths, output, "")
+}
+
+// Make creates a .tar.bz2 file at tarbz2Path containing
+// the contents of files listed in filePaths. File paths
+// can be those of regular files or directories. Regular
+// files are stored at the 'root' of the archive, and
+// directories are recursively added.
+func (tarBz2Format) Make(tarbz2Path string, filePaths []string) error {
+	out, err := os.Create(tarbz2Path)
+	if err != nil {
+		return fmt.Errorf("error creating %s: %v", tarbz2Path, err)
+	}
+	defer out.Close()
+
+	return writeTarBz2(filePaths, out, tarbz2Path)
+}
+
+func writeTarBz2(filePaths []string, output io.Writer, dest string) error {
+	bz2w, err := bzip2.NewWriter(output, nil)
+	if err != nil {
+		return fmt.Errorf("error compressing bzip2: %v", err)
+	}
+	defer bz2w.Close()
+
+	return writeTar(filePaths, bz2w, dest)
+}
+
+// Read untars a .tar.bz2 file read from a Reader and decompresses
+// the contents into destination.
+func (tarBz2Format) Read(input io.Reader, destination string) error {
+	bz2r, err := bzip2.NewReader(input, nil)
+	if err != nil {
+		return fmt.Errorf("error decompressing bzip2: %v", err)
+	}
+	defer bz2r.Close()
+
+	return Tar.Read(bz2r, destination)
+}
+
+// Open untars source and decompresses the contents into destination.
+func (tarBz2Format) Open(source, destination string) error {
+	f, err := os.Open(source)
+	if err != nil {
+		return fmt.Errorf("%s: failed to open archive: %v", source, err)
+	}
+	defer f.Close()
+
+	return TarBz2.Read(f, destination)
+}