Add xl-meta data extraction (#12396)

* Add `-export` flag to export data.
* Support wildcard inputs.

docs/bucket/versioning/xl-meta.go

@@ -27,6 +27,7 @@ import (
 	"io/ioutil"
 	"log"
 	"os"
+	"path/filepath"
 
 	"github.com/minio/cli"
 	"github.com/tinylib/msgp/msgp"
@@ -42,6 +43,11 @@ func main() {
 
 USAGE:
   {{.Name}} {{if .VisibleFlags}}[FLAGS]{{end}} METAFILES...
+
+Multiple files can be added.
+Wildcards are accepted: testdir/*.txt will compress all files in testdir ending with .txt
+Directories can be wildcards as well. testdir/*/*.txt will match testdir/subdir/b.txt
+
 {{if .VisibleFlags}}
 GLOBAL FLAGS:
   {{range .VisibleFlags}}{{.}}
@@ -59,13 +65,28 @@ GLOBAL FLAGS:
 			Usage: "Display inline data keys and sizes",
 			Name:  "data",
 		},
+		cli.BoolFlag{
+			Usage: "Export inline data",
+			Name:  "export",
+		},
 	}
 
 	app.Action = func(c *cli.Context) error {
-		files := c.Args()
-		if len(files) == 0 {
+		args := c.Args()
+		if len(args) == 0 {
 			// If no args, assume xl.meta
-			files = []string{"xl.meta"}
+			args = []string{"xl.meta"}
+		}
+		var files []string
+		for _, pattern := range args {
+			found, err := filepath.Glob(pattern)
+			if err != nil {
+				return err
+			}
+			if len(found) == 0 {
+				return fmt.Errorf("unable to find file %v", pattern)
+			}
+			files = append(files, found...)
 		}
 		for _, file := range files {
 			var r io.Reader
@@ -124,6 +145,14 @@ GLOBAL FLAGS:
 				}
 				buf = bytes.NewBuffer(b)
 			}
+			if c.Bool("export") {
+				err := data.files(func(name string, data []byte) {
+					ioutil.WriteFile(fmt.Sprintf("%s-%s.data", file, name), data, os.ModePerm)
+				})
+				if err != nil {
+					return err
+				}
+			}
 			if c.Bool("ndjson") {
 				fmt.Println(buf.String())
 				continue
@@ -257,3 +286,38 @@ func (x xlMetaInlineData) json() ([]byte, error) {
 	res = append(res, '}')
 	return res, nil
 }
+
+// files returns files as callback.
+func (x xlMetaInlineData) files(fn func(name string, data []byte)) error {
+	if len(x) == 0 {
+		return nil
+	}
+	if !x.versionOK() {
+		return errors.New("xlMetaInlineData: unknown version")
+	}
+
+	sz, buf, err := msgp.ReadMapHeaderBytes(x.afterVersion())
+	if err != nil {
+		return err
+	}
+
+	for i := uint32(0); i < sz; i++ {
+		var key, val []byte
+		key, buf, err = msgp.ReadMapKeyZC(buf)
+		if err != nil {
+			return err
+		}
+		if len(key) == 0 {
+			return fmt.Errorf("xlMetaInlineData: key %d is length 0", i)
+		}
+		// Read data...
+		val, buf, err = msgp.ReadBytesZC(buf)
+		if err != nil {
+			return err
+		}
+		// Call back.
+		fn(string(key), val)
+	}
+	return nil
+
+}