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/rar.go

@@ -0,0 +1,109 @@
+package archiver
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/nwaples/rardecode"
+)
+
+// Rar is for RAR archive format
+var Rar rarFormat
+
+func init() {
+	RegisterFormat("Rar", Rar)
+}
+
+type rarFormat struct{}
+
+func (rarFormat) Match(filename string) bool {
+	return strings.HasSuffix(strings.ToLower(filename), ".rar") || isRar(filename)
+}
+
+// isRar checks the file has the RAR 1.5 or 5.0 format signature by reading its
+// beginning bytes and matching it
+func isRar(rarPath string) bool {
+	f, err := os.Open(rarPath)
+	if err != nil {
+		return false
+	}
+	defer f.Close()
+
+	buf := make([]byte, 8)
+	if n, err := f.Read(buf); err != nil || n < 8 {
+		return false
+	}
+
+	return bytes.Equal(buf[:7], []byte("Rar!\x1a\x07\x00")) || // ver 1.5
+		bytes.Equal(buf, []byte("Rar!\x1a\x07\x01\x00")) // ver 5.0
+}
+
+// Write outputs a .rar archive, but this is not implemented because
+// RAR is a proprietary format. It is here only for symmetry with
+// the other archive formats in this package.
+func (rarFormat) Write(output io.Writer, filePaths []string) error {
+	return fmt.Errorf("write: RAR not implemented (proprietary format)")
+}
+
+// Make makes a .rar archive, but this is not implemented because
+// RAR is a proprietary format. It is here only for symmetry with
+// the other archive formats in this package.
+func (rarFormat) Make(rarPath string, filePaths []string) error {
+	return fmt.Errorf("make %s: RAR not implemented (proprietary format)", rarPath)
+}
+
+// Read extracts the RAR file read from input and puts the contents
+// into destination.
+func (rarFormat) Read(input io.Reader, destination string) error {
+	rr, err := rardecode.NewReader(input, "")
+	if err != nil {
+		return fmt.Errorf("read: failed to create reader: %v", err)
+	}
+
+	for {
+		header, err := rr.Next()
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			return err
+		}
+
+		if header.IsDir {
+			err = mkdir(filepath.Join(destination, header.Name))
+			if err != nil {
+				return err
+			}
+			continue
+		}
+
+		// if files come before their containing folders, then we must
+		// create their folders before writing the file
+		err = mkdir(filepath.Dir(filepath.Join(destination, header.Name)))
+		if err != nil {
+			return err
+		}
+
+		err = writeNewFile(filepath.Join(destination, header.Name), rr, header.Mode())
+		if err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// Open extracts the RAR file at source and puts the contents
+// into destination.
+func (rarFormat) Open(source, destination string) error {
+	rf, err := os.Open(source)
+	if err != nil {
+		return fmt.Errorf("%s: failed to open file: %v", source, err)
+	}
+	defer rf.Close()
+
+	return Rar.Read(rf, destination)
+}