restic/internal/dump/tar.go

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package dump
import (
"archive/tar"
"context"
"io"
"os"
"path"
"path/filepath"
"strings"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/restic"
"github.com/restic/restic/internal/walker"
)
// WriteTar will write the contents of the given tree, encoded as a tar to the given destination.
// It will loop over all nodes in the tree and dump them recursively.
func WriteTar(ctx context.Context, repo restic.Repository, tree *restic.Tree, rootPath string, dst io.Writer) error {
tw := tar.NewWriter(dst)
for _, rootNode := range tree.Nodes {
rootNode.Path = rootPath
err := tarTree(ctx, repo, rootNode, rootPath, tw)
if err != nil {
_ = tw.Close()
return err
}
}
return tw.Close()
}
func tarTree(ctx context.Context, repo restic.Repository, rootNode *restic.Node, rootPath string, tw *tar.Writer) error {
rootNode.Path = path.Join(rootNode.Path, rootNode.Name)
rootPath = rootNode.Path
if err := tarNode(ctx, tw, rootNode, repo); err != nil {
return err
}
// If this is no directory we are finished
if !IsDir(rootNode) {
return nil
}
err := walker.Walk(ctx, repo, *rootNode.Subtree, nil, func(_ restic.ID, nodepath string, node *restic.Node, err error) (bool, error) {
if err != nil {
return false, err
}
if node == nil {
return false, nil
}
node.Path = path.Join(rootPath, nodepath)
if IsFile(node) || IsLink(node) || IsDir(node) {
err := tarNode(ctx, tw, node, repo)
if err != nil {
return false, err
}
}
return false, nil
})
return err
}
// copied from archive/tar.FileInfoHeader
const (
// Mode constants from the USTAR spec:
// See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_06
c_ISUID = 04000 // Set uid
c_ISGID = 02000 // Set gid
c_ISVTX = 01000 // Save text (sticky bit)
)
func tarNode(ctx context.Context, tw *tar.Writer, node *restic.Node, repo restic.Repository) error {
relPath, err := filepath.Rel("/", node.Path)
if err != nil {
return err
}
header := &tar.Header{
Name: filepath.ToSlash(relPath),
Size: int64(node.Size),
Mode: int64(node.Mode.Perm()), // c_IS* constants are added later
Uid: int(node.UID),
Gid: int(node.GID),
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Uname: node.User,
Gname: node.Group,
ModTime: node.ModTime,
AccessTime: node.AccessTime,
ChangeTime: node.ChangeTime,
PAXRecords: parseXattrs(node.ExtendedAttributes),
}
// adapted from archive/tar.FileInfoHeader
if node.Mode&os.ModeSetuid != 0 {
header.Mode |= c_ISUID
}
if node.Mode&os.ModeSetgid != 0 {
header.Mode |= c_ISGID
}
if node.Mode&os.ModeSticky != 0 {
header.Mode |= c_ISVTX
}
if IsFile(node) {
header.Typeflag = tar.TypeReg
}
if IsLink(node) {
header.Typeflag = tar.TypeSymlink
header.Linkname = node.LinkTarget
}
if IsDir(node) {
header.Typeflag = tar.TypeDir
header.Name += "/"
}
err = tw.WriteHeader(header)
if err != nil {
return errors.Wrap(err, "TarHeader ")
}
return GetNodeData(ctx, tw, repo, node)
}
func parseXattrs(xattrs []restic.ExtendedAttribute) map[string]string {
tmpMap := make(map[string]string)
for _, attr := range xattrs {
attrString := string(attr.Value)
if strings.HasPrefix(attr.Name, "system.posix_acl_") {
na := acl{}
na.decode(attr.Value)
if na.String() != "" {
if strings.Contains(attr.Name, "system.posix_acl_access") {
tmpMap["SCHILY.acl.access"] = na.String()
} else if strings.Contains(attr.Name, "system.posix_acl_default") {
tmpMap["SCHILY.acl.default"] = na.String()
}
}
} else {
tmpMap["SCHILY.xattr."+attr.Name] = attrString
}
}
return tmpMap
}
// GetNodeData will write the contents of the node to the given output
func GetNodeData(ctx context.Context, output io.Writer, repo restic.Repository, node *restic.Node) error {
var (
buf []byte
err error
)
for _, id := range node.Content {
buf, err = repo.LoadBlob(ctx, restic.DataBlob, id, buf)
if err != nil {
return err
}
_, err = output.Write(buf)
if err != nil {
return errors.Wrap(err, "Write")
}
}
return nil
}
// IsDir checks if the given node is a directory
func IsDir(node *restic.Node) bool {
return node.Type == "dir"
}
// IsLink checks if the given node as a link
func IsLink(node *restic.Node) bool {
return node.Type == "symlink"
}
// IsFile checks if the given node is a file
func IsFile(node *restic.Node) bool {
return node.Type == "file"
}