Added MD5 Checksum Support

This patch adds support for creating embedded files with their MD5
checksum calculated at time of the buffer generation and stored
alongside the asset information. The checksum feature can be enabled via
the command line with the `--md5checksum` flag. The default value for
the flag is `false`.

Author: akutz

config.go

@@ -140,6 +140,10 @@ type Config struct {
 	//
 	// This parameter can be provided multiple times.
 	Ignore []*regexp.Regexp
+
+	// MD5Checksum is a flag that, when set to true, indicates to calculate
+	// MD5 checksums for files.
+	MD5Checksum bool
 }
 
 // NewConfig returns a default configuration struct.

go-bindata/main.go

@@ -48,6 +48,7 @@ func parseArgs() *bindata.Config {
 	flag.BoolVar(&c.NoMemCopy, "nomemcopy", c.NoMemCopy, "Use a .rodata hack to get rid of unnecessary memcopies. Refer to the documentation to see what implications this carries.")
 	flag.BoolVar(&c.NoCompress, "nocompress", c.NoCompress, "Assets will *not* be GZIP compressed when this flag is specified.")
 	flag.BoolVar(&c.NoMetadata, "nometadata", c.NoMetadata, "Assets will not preserve size, mode, and modtime info.")
+	flag.BoolVar(&c.MD5Checksum, "md5checksum", c.MD5Checksum, "MD5 checksums will be calculated for assets.")
 	flag.UintVar(&c.Mode, "mode", c.Mode, "Optional file mode override for all files.")
 	flag.Int64Var(&c.ModTime, "modtime", c.ModTime, "Optional modification unix timestamp override for all files.")
 	flag.StringVar(&c.Output, "o", c.Output, "Optional name of the output file to be generated.")

release.go

@@ -7,6 +7,7 @@ package bindata
 import (
 	"bytes"
 	"compress/gzip"
+	"crypto/md5"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -214,14 +215,20 @@ func header_uncompressed_memcopy(w io.Writer) error {
 func header_release_common(w io.Writer) error {
 	_, err := fmt.Fprintf(w, `type asset struct {
 	bytes []byte
-	info  os.FileInfo
+	info  fileInfoEx
+}
+
+type fileInfoEx interface {
+	os.FileInfo
+	MD5Checksum() string
 }
 
 type bindataFileInfo struct {
-	name    string
-	size    int64
-	mode    os.FileMode
-	modTime time.Time
+	name        string
+	size        int64
+	mode        os.FileMode
+	modTime     time.Time
+	md5checksum string
 }
 
 func (fi bindataFileInfo) Name() string {
@@ -236,6 +243,9 @@ func (fi bindataFileInfo) Mode() os.FileMode {
 func (fi bindataFileInfo) ModTime() time.Time {
 	return fi.modTime
 }
+func (fi bindataFileInfo) MD5Checksum() string {
+	return fi.md5checksum
+}
 func (fi bindataFileInfo) IsDir() bool {
 	return false
 }
@@ -371,17 +381,30 @@ func asset_release_common(w io.Writer, c *Config, asset *Asset) error {
 	if c.ModTime > 0 {
 		modTime = c.ModTime
 	}
+
+	var md5checksum string
+	if c.MD5Checksum {
+		buf, err := ioutil.ReadFile(asset.Path)
+		if err != nil {
+			return err
+		}
+		h := md5.New()
+		if _, err := h.Write(buf); err != nil {
+			return err
+		}
+		md5checksum = fmt.Sprintf("%x", h.Sum(nil))
+	}
 	_, err = fmt.Fprintf(w, `func %s() (*asset, error) {
 	bytes, err := %sBytes()
 	if err != nil {
 		return nil, err
 	}
 
-	info := bindataFileInfo{name: %q, size: %d, mode: os.FileMode(%d), modTime: time.Unix(%d, 0)}
+	info := bindataFileInfo{name: %q, size: %d, md5checksum: %q, mode: os.FileMode(%d), modTime: time.Unix(%d, 0)}
 	a := &asset{bytes: bytes, info: info}
 	return a, nil
 }
 
-`, asset.Func, asset.Func, asset.Name, size, mode, modTime)
+`, asset.Func, asset.Func, asset.Name, size, md5checksum, mode, modTime)
 	return err
 }