Consolidate GetImageVirtualSize and DetectFileFormat functions

Signed-off-by: Tim Serong <tserong@suse.com>

pkg/backingimage/backingimage.go

@@ -183,13 +183,13 @@ func OpenBackingImage(path string) (*BackingImage, error) {
 		return nil, err
 	}
 
-	format, err := util.DetectFileFormat(file)
+	imgInfo, err := util.GetQemuImgInfo(file)
 	if err != nil {
 		return nil, err
 	}
 
 	var f enginetypes.DiffDisk
-	switch format {
+	switch imgInfo.Format {
 	case "qcow2":
 		// This is only used when doing backup.
 		// We open qcow2 like raw file and simply backup all the blocks of the qcow2
@@ -202,7 +202,7 @@ func OpenBackingImage(path string) (*BackingImage, error) {
 			return nil, err
 		}
 	default:
-		return nil, fmt.Errorf("format %v of the backing file %v is not supported", format, file)
+		return nil, fmt.Errorf("format %v of the backing file %v is not supported", imgInfo.Format, file)
 	}
 
 	size, err := f.Size()
@@ -224,7 +224,7 @@ func OpenBackingImage(path string) (*BackingImage, error) {
 		SectorSize: diskutil.BackingImageSectorSize,
 		Path:       file,
 		Disk:       f,
-		Format:     format,
+		Format:     imgInfo.Format,
 
 		Location: location,
 	}, nil

pkg/sync/server_test.go

@@ -501,9 +501,9 @@ func (s *SyncTestSuite) TestDownloadToDst(c *C) {
 	c.Assert(err, IsNil)
 	c.Assert(downloadChecksum, Equals, checksum)
 	// Downloaded file can be identified as a qcow2 file as well.
-	downloadFileFormat, err := util.DetectFileFormat(unzipDownloadFilePath)
+	downloadFileInfo, err := util.GetQemuImgInfo(unzipDownloadFilePath)
 	c.Assert(err, IsNil)
-	c.Assert(downloadFileFormat, Equals, "qcow2")
+	c.Assert(downloadFileInfo.Format, Equals, "qcow2")
 }
 
 func (s *SyncTestSuite) TestDuplicateCalls(c *C) {

pkg/sync/sync_file.go

@@ -820,14 +820,14 @@ func (sf *SyncingFile) updateSyncReadyNoLock() {
 func (sf *SyncingFile) updateVirtualSizeNoLock(filePath string) {
 	// This only works if filePath is valid - sometimes we need to call it
 	// with sf.tmpFilePath, sometimes with sf.filePath :-/
-	virtualSize, err := util.GetImageVirtualSize(filePath)
+	imgInfo, err := util.GetQemuImgInfo(filePath)
 	if err != nil {
 		sf.log.Warnf("SyncingFile: failed to get backing image virtual size: %v", err)
 	}
 	// This will be zero when there is an error, which allows components
 	// further up the stack to know that the virtual size somehow isn't
 	// available yet.
-	sf.virtualSize = virtualSize
+	sf.virtualSize = imgInfo.VirtualSize
 }
 
 func (sf *SyncingFile) handleFailureNoLock(err error) {

pkg/util/util.go

@@ -1,7 +1,6 @@
 package util
 
 import (
-	"bufio"
 	"bytes"
 	"compress/gzip"
 	"context"
@@ -15,7 +14,6 @@ import (
 	"os/exec"
 	"path/filepath"
 	"regexp"
-	"strings"
 	"time"
 
 	"github.com/pkg/errors"
@@ -233,68 +231,27 @@ func ExecuteWithTimeout(timeout time.Duration, envs []string, binary string, arg
 	return output.String(), nil
 }
 
-func DetectFileFormat(filePath string) (string, error) {
-
-	/* Example command outputs
-	   $ qemu-img info parrot.raw
-	   image: parrot.raw
-	   file format: raw
-	   virtual size: 32M (33554432 bytes)
-	   disk size: 2.2M
-
-	   $ qemu-img info parrot.qcow2
-	   image: parrot.qcow2
-	   file format: qcow2
-	   virtual size: 32M (33554432 bytes)
-	   disk size: 2.3M
-	   cluster_size: 65536
-	   Format specific information:
-	       compat: 1.1
-	       lazy refcounts: false
-	       refcount bits: 16
-	       corrupt: false
-	*/
-
-	output, err := Execute([]string{}, QemuImgBinary, "info", filePath)
-	if err != nil {
-		return "", err
-	}
-
-	scanner := bufio.NewScanner(strings.NewReader(output))
-	for scanner.Scan() {
-		line := strings.TrimSpace(scanner.Text())
-		if strings.HasPrefix(line, "file format: ") {
-			return strings.TrimPrefix(line, "file format: "), nil
-		}
-	}
-
-	return "", fmt.Errorf("cannot find the file format in the output %s", output)
+type QemuImgInfo struct {
+	// For qcow2 files, VirtualSize may be larger than the physical
+	// image size on disk.  For raw files, `qemu-img info` will report
+	// VirtualSize as being the same as the physical file size.
+	VirtualSize int64  `json:"virtual-size"`
+	Format      string `json:"format"`
 }
 
-func GetImageVirtualSize(filePath string) (int64, error) {
-	type qemuImgInfo struct {
-		VirtualSize int64 `json:"virtual-size"`
-	}
-
+func GetQemuImgInfo(filePath string) (imgInfo QemuImgInfo, err error) {
 	output, err := Execute([]string{}, QemuImgBinary, "info", "--output=json", filePath)
 	if err != nil {
-		return 0, err
+		return
 	}
-
-	var q qemuImgInfo
-	err = json.Unmarshal([]byte(output), &q)
-	if err != nil {
-		return 0, err
-	}
-
-	// If it's a raw file, `qemu-img info` will return virtual size == size
-	return q.VirtualSize, nil
+	err = json.Unmarshal([]byte(output), &imgInfo)
+	return
 }
 
 func ConvertFromRawToQcow2(filePath string) error {
-	if format, err := DetectFileFormat(filePath); err != nil {
+	if imgInfo, err := GetQemuImgInfo(filePath); err != nil {
 		return err
-	} else if format == "qcow2" {
+	} else if imgInfo.Format == "qcow2" {
 		return nil
 	}