forked from TrueCloudLab/restic
aaf5254e26
The old version was taken from an MPL-licensed library. This is a cleanroom implementation. The code is shorter and it's now explicit that only Linux ACLs are supported.
133 lines
3 KiB
Go
133 lines
3 KiB
Go
package dump
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import (
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"archive/tar"
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"context"
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"fmt"
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"os"
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"path/filepath"
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"github.com/restic/restic/internal/debug"
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"github.com/restic/restic/internal/errors"
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"github.com/restic/restic/internal/restic"
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)
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func (d *Dumper) dumpTar(ctx context.Context, ch <-chan *restic.Node) (err error) {
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w := tar.NewWriter(d.w)
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defer func() {
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if err == nil {
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err = w.Close()
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err = errors.Wrap(err, "Close")
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}
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}()
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for node := range ch {
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if err := d.dumpNodeTar(ctx, node, w); err != nil {
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return err
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}
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}
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return nil
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}
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// copied from archive/tar.FileInfoHeader
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const (
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// Mode constants from the USTAR spec:
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// See http://pubs.opengroup.org/onlinepubs/9699919799/utilities/pax.html#tag_20_92_13_06
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cISUID = 0o4000 // Set uid
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cISGID = 0o2000 // Set gid
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cISVTX = 0o1000 // Save text (sticky bit)
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)
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// in a 32-bit build of restic:
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// substitute a uid or gid of -1 (which was converted to 2^32 - 1) with 0
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func tarIdentifier(id uint32) int {
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if int(id) == -1 {
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return 0
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}
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return int(id)
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}
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func (d *Dumper) dumpNodeTar(ctx context.Context, node *restic.Node, w *tar.Writer) error {
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relPath, err := filepath.Rel("/", node.Path)
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if err != nil {
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return err
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}
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header := &tar.Header{
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Name: filepath.ToSlash(relPath),
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Size: int64(node.Size),
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Mode: int64(node.Mode.Perm()), // cIS* constants are added later
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Uid: tarIdentifier(node.UID),
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Gid: tarIdentifier(node.GID),
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Uname: node.User,
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Gname: node.Group,
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ModTime: node.ModTime,
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AccessTime: node.AccessTime,
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ChangeTime: node.ChangeTime,
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PAXRecords: parseXattrs(node.ExtendedAttributes),
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}
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// adapted from archive/tar.FileInfoHeader
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if node.Mode&os.ModeSetuid != 0 {
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header.Mode |= cISUID
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}
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if node.Mode&os.ModeSetgid != 0 {
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header.Mode |= cISGID
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}
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if node.Mode&os.ModeSticky != 0 {
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header.Mode |= cISVTX
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}
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if IsFile(node) {
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header.Typeflag = tar.TypeReg
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}
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if IsLink(node) {
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header.Typeflag = tar.TypeSymlink
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header.Linkname = node.LinkTarget
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}
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if IsDir(node) {
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header.Typeflag = tar.TypeDir
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header.Name += "/"
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}
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err = w.WriteHeader(header)
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if err != nil {
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return fmt.Errorf("writing header for %q: %w", node.Path, err)
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}
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return d.writeNode(ctx, w, node)
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}
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func parseXattrs(xattrs []restic.ExtendedAttribute) map[string]string {
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tmpMap := make(map[string]string)
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for _, attr := range xattrs {
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// Check for Linux POSIX.1e ACLs.
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//
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// TODO support ACLs from other operating systems.
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// FreeBSD ACLs have names "posix1e.acl_(access|default)",
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// but their binary format may not match the Linux format.
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aclKey := ""
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switch attr.Name {
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case "system.posix_acl_access":
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aclKey = "SCHILY.acl.access"
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case "system.posix_acl_default":
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aclKey = "SCHILY.acl.default"
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}
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if aclKey != "" {
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text, err := formatLinuxACL(attr.Value)
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if err != nil {
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debug.Log("parsing Linux ACL: %v, skipping", err)
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continue
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}
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tmpMap[aclKey] = text
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} else {
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tmpMap["SCHILY.xattr."+attr.Name] = string(attr.Value)
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}
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}
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return tmpMap
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}
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