clone image before creating vm

This PR changes the behavior of the noopImagePuller. As this puller does
not actually pull any image as it is used when an image is already in
the local system, it just clones the image in a dedicated folder so that
the original image does not get alterated when started by macadam.

Signed-off-by: lstocchi <[email protected]>

Author: lstocchi

cmd/macadam/init.go

@@ -186,8 +186,10 @@ func initMachine(cmd *cobra.Command, args []string) error {
 		return fmt.Errorf("invalid name %q: %w", machineName, ldefine.RegexError)
 	}
 
+	puller := imagepullers.NewNoopImagePuller(machineName, provider.VMType())
+
 	initOpts := macadam.DefaultInitOpts(machineName)
-	initOpts.ImagePuller = &imagepullers.NoopImagePuller{}
+	initOpts.ImagePuller = puller
 	initOpts.ImagePuller.SetSourceURI(diskImage)
 	initOpts.Name = machineName
 	initOpts.Image = diskImage

pkg/imagepullers/noop.go

@@ -1,23 +1,92 @@
 package imagepullers
 
 import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strings"
+
 	"github.com/containers/podman/v5/pkg/machine/define"
+
+	"github.com/containers/podman/v5/pkg/machine/env"
 )
 
 type NoopImagePuller struct {
-	localPath string
+	localPath   *define.VMFile
+	sourceURI   string
+	vmType      define.VMType
+	machineName string
+}
+
+func NewNoopImagePuller(machineName string, vmType define.VMType) *NoopImagePuller {
+	return &NoopImagePuller{
+		machineName: machineName,
+		vmType:      vmType,
+	}
 }
 
-var _ define.ImagePuller = &NoopImagePuller{}
+func (puller *NoopImagePuller) SetSourceURI(sourcePath string) {
+	puller.sourceURI = sourcePath
+}
 
-func (puller *NoopImagePuller) SetSourceURI(localPath string) {
-	puller.localPath = localPath
+func imageExtension(sourceURI string) string {
+	if strings.HasSuffix(sourceURI, ".tar.gz") {
+		return "tar.gz"
+	}
+	return filepath.Ext(sourceURI)
 }
 
 func (puller *NoopImagePuller) LocalPath() (*define.VMFile, error) {
-	return define.NewMachineFile(puller.localPath, nil)
+	// if localPath has already been calculated returns it
+	if puller.localPath != nil {
+		return puller.localPath, nil
+	}
+
+	// calculate and set localPath
+	dirs, err := env.GetMachineDirs(puller.vmType)
+	if err != nil {
+		return nil, err
+	}
+
+	vmFile, err := dirs.DataDir.AppendToNewVMFile(fmt.Sprintf("%s-%s.%s", puller.machineName, puller.vmType.String(), imageExtension(puller.sourceURI)), nil)
+	if err != nil {
+		return nil, err
+	}
+	puller.localPath = vmFile
+	return vmFile, nil
 }
 
+/*
+The noopImageBuilder does not actually download any image as the image is already stored locally.
+The download func is used to make a copy of the source image so that the user image is not modified
+by macadam
+*/
 func (puller *NoopImagePuller) Download() error {
-	return nil
+	localPath, err := puller.LocalPath()
+	if err != nil {
+		return err
+	}
+	return copyFile(puller.sourceURI, localPath.Path)
+}
+
+func copyFile(src, dst string) error {
+	in, err := os.Open(src)
+	if err != nil {
+		return err
+	}
+	defer in.Close()
+
+	out, err := os.Create(dst)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	bufferedWriter := bufio.NewWriter(out)
+	defer bufferedWriter.Flush()
+
+	_, err = io.Copy(bufferedWriter, in)
+	return err
 }