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FreeBSD: fix tar headers & the nil check on getxattr

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On FreeBSD + zfs, stat call seem to return garbage in RDev for regular
files & folders. The value returned is large enough not to fit into
`Devmajor` & `Devminor` fields of the tar header. Fortunately, these
fields are required just for special devices.

This change

* adds a check into `setHeaderForSpecialDevice` that the
  input header represents a special device. If it's not the case, we
  don't set the Devmajor & Devminor fields.

* fixes the nil check on `getxattr`: it never returns nils, but rather
  an empty slice instead

Signed-off-by: Artem Khramov <akhramov@pm.me>
This commit is contained in:
Artem Khramov 2021-09-13 20:18:11 +03:00
parent cbf9d88c9e
commit 2bffb5f9b2
No known key found for this signature in database
GPG Key ID: 6CB5147BFFBCC525
2 changed files with 16 additions and 1 deletions
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2
archive/tar.go
View File

@ -598,7 +598,7 @@ func (cw *ChangeWriter) HandleChange(k fs.ChangeKind, p string, f os.FileInfo, e
if capability, err := getxattr(source, "security.capability"); err != nil {
return errors.Wrap(err, "failed to get capabilities xattr")
} else if capability != nil {
} else if len(capability) > 0 {
if hdr.PAXRecords == nil {
hdr.PAXRecords = map[string]string{}
}

15
archive/tar_unix.go
View File

@ -22,6 +22,7 @@ package archive
import (
"archive/tar"
"os"
"runtime"
"strings"
"syscall"
@ -41,6 +42,20 @@ func chmodTarEntry(perm os.FileMode) os.FileMode {
}
func setHeaderForSpecialDevice(hdr *tar.Header, name string, fi os.FileInfo) error {
// Devmajor and Devminor are only needed for special devices.
// In FreeBSD, RDev for regular files is -1 (unless overridden by FS):
// https://cgit.freebsd.org/src/tree/sys/kern/vfs_default.c?h=stable/13#n1531
// (NODEV is -1: https://cgit.freebsd.org/src/tree/sys/sys/param.h?h=stable/13#n241).
// ZFS in particular does not override the default:
// https://cgit.freebsd.org/src/tree/sys/contrib/openzfs/module/os/freebsd/zfs/zfs_vnops_os.c?h=stable/13#n2027
// Since `Stat_t.Rdev` is uint64, the cast turns -1 into (2^64 - 1).
// Such large values cannot be encoded in a tar header.
if runtime.GOOS == "freebsd" && hdr.Typeflag != tar.TypeBlock && hdr.Typeflag != tar.TypeChar {
return nil
}
s, ok := fi.Sys().(*syscall.Stat_t)
if !ok {
return errors.New("unsupported stat type")