Implement new findPartUUID that uses github.com/u-root/u-root/pkg/mount/gpt

go.mod

@@ -7,5 +7,6 @@ replace github.com/cavaliercoder/grab => ./grab
 require (
 	github.com/cavaliercoder/grab v2.0.0+incompatible
 	github.com/lordwelch/pathvalidate v0.0.0-20201012043703-54efa7ea1308
+	github.com/u-root/u-root v7.0.0+incompatible
 	golang.org/x/net v0.0.0-20201209123823-ac852fbbde11
 )

go.sum

@@ -1,5 +1,8 @@
 github.com/lordwelch/pathvalidate v0.0.0-20201012043703-54efa7ea1308 h1:CkcsZK6QYg59rc92eqU2h+FRjWltCIiplmEwIB05jfM=
 github.com/lordwelch/pathvalidate v0.0.0-20201012043703-54efa7ea1308/go.mod h1:4I4r5Y/LkH+34KACiudU+Q27ooz7xSDyVEuWAVKeJEQ=
+github.com/u-root/u-root v1.0.0 h1:3hJy0CG3mXIZtWRE+yrghG/3H0v8L1qEeZBlPr5nS9s=
+github.com/u-root/u-root v7.0.0+incompatible h1:u+KSS04pSxJGI5E7WE4Bs9+Zd75QjFv+REkjy/aoAc8=
+github.com/u-root/u-root v7.0.0+incompatible/go.mod h1:RYkpo8pTHrNjW08opNd/U6p/RJE7K0D8fXO0d47+3YY=
 golang.org/x/net v0.0.0-20201209123823-ac852fbbde11 h1:lwlPPsmjDKK0J6eG6xDWd5XPehI0R024zxjDnw3esPA=
 golang.org/x/net v0.0.0-20201209123823-ac852fbbde11/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
 golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

main.go

@@ -1,7 +1,6 @@
 package main
 
 import (
-	"encoding/binary"
 	"errors"
 	"flag"
 	"fmt"
@@ -10,8 +9,11 @@ import (
 	"log"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"syscall"
+
+	"github.com/u-root/u-root/pkg/mount/gpt"
 )
 
 var (
@@ -37,7 +39,7 @@ func mount() error {
 	var (
 		partUUIDb []byte
 		partUUID  string
-		dev       string
+		dev       part
 		err       error
 		dataStat  os.FileInfo
 		dataDir   = filepath.Join(gloaderHome, "data")
@@ -71,11 +73,11 @@ func mount() error {
 		_, err = folder.Readdir(1)
 		if errors.Is(err, io.EOF) {
 			fmt.Printf("mount %s %s", partUUID, dataDir)
-			dev, err = findPartUUID(partUUID)
+			dev = findPartUUID(partUUID)
 			if err != nil {
 				return fmt.Errorf("error mounting datadir: %w", err)
 			}
-			err = syscall.Mount(dev, dataDir, "ext4", 0, "")
+			err = syscall.Mount(dev.Path, dataDir, "ext4", 0, "")
 			if err != nil {
 				return fmt.Errorf("error mounting datadir: %w", err)
 			}
@@ -86,11 +88,66 @@ func mount() error {
 	return fmt.Errorf("error mounting datadir: data dir %s is not a directory", dataDir)
 }
 
-func findPartUUID(uuid string) (string, error) {
+// func findPartUUID(uuid string) (string, error) {
-	var dev string
+// 	var dev string
+// 	err := filepath.Walk("/sys/block", func(path string, info os.FileInfo, err error) error {
+// 		if err != nil {
+// 			log.Printf("findPartUUID: %v", err)
+// 			return nil
+// 		}
+// 		if info.Mode()&os.ModeSymlink == 0 {
+// 			return nil
+// 		}
+// 		devname := "/dev/" + filepath.Base(path)
+// 		f, err := os.Open(devname)
+// 		if err != nil {
+// 			log.Printf("findPartUUID: %v", err)
+// 			return nil
+// 		}
+// 		defer f.Close()
+// 		if _, err := f.Seek(440, io.SeekStart); err != nil {
+// 			var se syscall.Errno
+// 			if errors.As(err, &se) && se == syscall.EINVAL {
+// 				// Seek()ing empty loop devices results in EINVAL.
+// 				return nil
+// 			}
+// 			log.Printf("findPartUUID: %v(%T)", err, err.(*os.PathError).Err)
+// 			return nil
+// 		}
+// 		var diskSig struct {
+// 			ID      uint32
+// 			Trailer uint16
+// 		}
+// 		if err := binary.Read(f, binary.LittleEndian, &diskSig); err != nil {
+// 			log.Printf("findPartUUID: %v", err)
+// 			return nil
+// 		}
+// 		if fmt.Sprintf("%08x", diskSig.ID) == uuid && diskSig.Trailer == 0 {
+// 			dev = devname
+// 			// TODO: abort early with sentinel error code
+// 			return nil
+// 		}
+// 		return nil
+// 	})
+// 	if err != nil {
+// 		return "", err
+// 	}
+// 	if dev == "" {
+// 		return "", fmt.Errorf("PARTUUID=%s not found", uuid)
+// 	}
+// 	return dev, nil
+// }
+
+type part struct {
+	UUID string
+	Path string
+}
+
+func findPartUUID(UUID string) part {
+	var dev part
 	err := filepath.Walk("/sys/block", func(path string, info os.FileInfo, err error) error {
 		if err != nil {
-			log.Printf("findPartUUID: %v", err)
+			log.Printf("listPartUUID: %v", err)
 			return nil
 		}
 		if info.Mode()&os.ModeSymlink == 0 {
@@ -99,39 +156,23 @@ func findPartUUID(uuid string) (string, error) {
 		devname := "/dev/" + filepath.Base(path)
 		f, err := os.Open(devname)
 		if err != nil {
-			log.Printf("findPartUUID: %v", err)
+			log.Printf("listPartUUID: %v", err)
 			return nil
 		}
 		defer f.Close()
-		if _, err := f.Seek(440, io.SeekStart); err != nil {
+		parttable, _ := gpt.New(f)
-			var se syscall.Errno
+		if parttable.Primary != nil {
-			if errors.As(err, &se) && se == syscall.EINVAL {
+			for i, partition := range parttable.Primary.Parts {
-				// Seek()ing empty loop devices results in EINVAL.
+				if partition.UniqueGUID.String() == UUID {
-				return nil
+					dev = part{UUID: partition.UniqueGUID.String(), Path: devname + strconv.Itoa(i+1)}
 				}
-			log.Printf("findPartUUID: %v(%T)", err, err.(*os.PathError).Err)
-			return nil
 			}
-		var diskSig struct {
-			ID      uint32
-			Trailer uint16
-		}
-		if err := binary.Read(f, binary.LittleEndian, &diskSig); err != nil {
-			log.Printf("findPartUUID: %v", err)
-			return nil
-		}
-		if fmt.Sprintf("%08x", diskSig.ID) == uuid && diskSig.Trailer == 0 {
-			dev = devname
-			// TODO: abort early with sentinel error code
-			return nil
 		}
+
 		return nil
 	})
 	if err != nil {
-		return "", err
+		return part{}
 	}
-	if dev == "" {
+	return dev
-		return "", fmt.Errorf("PARTUUID=%s not found", uuid)
-	}
-	return dev, nil
 }