Add U volume flag to chown source volumes

Signed-off-by: Eduardo Vega <edvegavalerio@gmail.com>

vendor/github.com/containers/common/pkg/chown/chown.go

@@ -0,0 +1,122 @@
+package chown
+
+import (
+	"os"
+	"os/user"
+	"path/filepath"
+	"syscall"
+
+	"github.com/containers/storage/pkg/homedir"
+	"github.com/pkg/errors"
+)
+
+// DangerousHostPath validates if a host path is dangerous and should not be modified
+func DangerousHostPath(path string) (bool, error) {
+	excludePaths := map[string]bool{
+		"/":           true,
+		"/bin":        true,
+		"/boot":       true,
+		"/dev":        true,
+		"/etc":        true,
+		"/etc/passwd": true,
+		"/etc/pki":    true,
+		"/etc/shadow": true,
+		"/home":       true,
+		"/lib":        true,
+		"/lib64":      true,
+		"/media":      true,
+		"/opt":        true,
+		"/proc":       true,
+		"/root":       true,
+		"/run":        true,
+		"/sbin":       true,
+		"/srv":        true,
+		"/sys":        true,
+		"/tmp":        true,
+		"/usr":        true,
+		"/var":        true,
+		"/var/lib":    true,
+		"/var/log":    true,
+	}
+
+	if home := homedir.Get(); home != "" {
+		excludePaths[home] = true
+	}
+
+	if sudoUser := os.Getenv("SUDO_USER"); sudoUser != "" {
+		if usr, err := user.Lookup(sudoUser); err == nil {
+			excludePaths[usr.HomeDir] = true
+		}
+	}
+
+	absPath, err := filepath.Abs(path)
+	if err != nil {
+		return true, err
+	}
+
+	realPath, err := filepath.EvalSymlinks(absPath)
+	if err != nil {
+		return true, err
+	}
+
+	if excludePaths[realPath] {
+		return true, nil
+	}
+
+	return false, nil
+}
+
+// ChangeHostPathOwnership changes the uid and gid ownership of a directory or file within the host.
+// This is used by the volume U flag to change source volumes ownership
+func ChangeHostPathOwnership(path string, recursive bool, uid, gid int) error {
+	// Validate if host path can be chowned
+	isDangerous, err := DangerousHostPath(path)
+	if err != nil {
+		return errors.Wrapf(err, "failed to validate if host path is dangerous")
+	}
+
+	if isDangerous {
+		return errors.Errorf("chowning host path %q is not allowed. You can manually `chown -R %d:%d %s`", path, uid, gid, path)
+	}
+
+	// Chown host path
+	if recursive {
+		err := filepath.Walk(path, func(filePath string, f os.FileInfo, err error) error {
+			if err != nil {
+				return err
+			}
+
+			// Get current ownership
+			currentUID := int(f.Sys().(*syscall.Stat_t).Uid)
+			currentGID := int(f.Sys().(*syscall.Stat_t).Gid)
+
+			if uid != currentUID || gid != currentGID {
+				return os.Lchown(filePath, uid, gid)
+			}
+
+			return nil
+		})
+
+		if err != nil {
+			return errors.Wrapf(err, "failed to chown recursively host path")
+		}
+	} else {
+		// Get host path info
+		f, err := os.Lstat(path)
+		if err != nil {
+			return errors.Wrapf(err, "failed to get host path information")
+		}
+
+		// Get current ownership
+		currentUID := int(f.Sys().(*syscall.Stat_t).Uid)
+		currentGID := int(f.Sys().(*syscall.Stat_t).Gid)
+
+		if uid != currentUID || gid != currentGID {
+			if err := os.Lchown(path, uid, gid); err != nil {
+				return errors.Wrapf(err, "failed to chown host path")
+			}
+		}
+	}
+
+	return nil
+}