restic/internal/dump/tar.go

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package dump
import (
"archive/tar"
"context"
"os"
"path/filepath"
"strings"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/restic"
)
func (d *Dumper) dumpTar(ctx context.Context, ch <-chan *restic.Node) (err error) {
w := tar.NewWriter(d.w)
defer func() {
if err == nil {
err = w.Close()
err = errors.Wrap(err, "Close")
}
}()
for node := range ch {
if err := d.dumpNodeTar(ctx, node, w); err != nil {
return err
}
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}
return nil
}
// 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
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cISUID = 0o4000 // Set uid
cISGID = 0o2000 // Set gid
cISVTX = 0o1000 // Save text (sticky bit)
)
// in a 32-bit build of restic:
// substitute a uid or gid of -1 (which was converted to 2^32 - 1) with 0
func tarIdentifier(id uint32) int {
if int(id) == -1 {
return 0
}
return int(id)
}
func (d *Dumper) dumpNodeTar(ctx context.Context, node *restic.Node, w *tar.Writer) error {
relPath, err := filepath.Rel("/", node.Path)
if err != nil {
return err
}
header := &tar.Header{
Name: filepath.ToSlash(relPath),
Size: int64(node.Size),
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Mode: int64(node.Mode.Perm()), // cIS* constants are added later
Uid: tarIdentifier(node.UID),
Gid: tarIdentifier(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 {
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header.Mode |= cISUID
}
if node.Mode&os.ModeSetgid != 0 {
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header.Mode |= cISGID
}
if node.Mode&os.ModeSticky != 0 {
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header.Mode |= cISVTX
}
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 = w.WriteHeader(header)
if err != nil {
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return errors.Wrap(err, "TarHeader")
}
return d.writeNode(ctx, w, 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
}