https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=290556
Bug ID: 290556
Summary: tar(8) may strip symlink target when reading from
cd9660 filesystem
Product: Base System
Version: Unspecified
Hardware: Any
OS: Any
Status: New
Severity: Affects Only Me
Priority: ---
Component: bin
Assignee: [email protected]
Reporter: [email protected]
PROBLEM
When creating a tarball from files on _some_ cd9660 filesystems (e.g. created
by xorrisofs(1)), all symbolic links will be stripped of their link target:
Expected:
lrwxr-xr-x 0 root wheel 0 27 Okt. 05:41 ./symlink-1 -> /some/fqfn
lrwxr-xr-x 0 root wheel 0 27 Okt. 05:41 ./symlink-2 -> ../relpath
lrwxr-xr-x 0 root wheel 0 27 Okt. 05:41 ./symlink-3 -> symlink-1
Found:
lrwxr-xr-x 0 root wheel 0 27 Okt. 05:41 ./symlink-1 ->
lrwxr-xr-x 0 root wheel 0 27 Okt. 05:41 ./symlink-2 ->
lrwxr-xr-x 0 root wheel 0 27 Okt. 05:41 ./symlink-3 ->
ANALYSIS
Even if tar(1) drops the symlink target when reading from a cd9660 filesystem,
it does extract them correctly from the device node or ISO image themselves.
Note that this error does not occur when the ISO has been created with
makefs(8):
makefs -t cd9660 -o rockridge -o label=TARPIT /tmp/tarpit.iso /tmp/tarpit
It does, however, occur when the image is created by xorrisofs(1):
xorrisofs -rock -volid TARPIT -o /tmp/tarpit.iso /tmp/tarpit
HOW TO REPRODUCE
# We need xorrisofs(1)
pkg install -y xorriso
# Create ISO image with symlinks
mkdir /tmp/tarpit
ln -s /some/fqfn /tmp/tarpit/symlink-1
ln -s ../relpath /tmp/tarpit/symlink-2
ln -s symlink-1 /tmp/tarpit/symlink-3
xorrisofs -rock -volid TARPIT -o /tmp/tarpit.iso /tmp/tarpit
# Mount ISO image
dev=$(mdconfig /tmp/tarpit.iso)
mount -t cd9660 /dev/iso9660/TARPIT
# Validate filesystem contents
ls -l /mnt
# total 0
# lrwxr-xr-x 1 root wheel 0 27 Okt. 05:41 symlink-1 -> /some/fqfn
# lrwxr-xr-x 1 root wheel 0 27 Okt. 05:41 symlink-2 -> ../relpath
# lrwxr-xr-x 1 root wheel 0 27 Okt. 05:41 symlink-3 -> symlink-1
# Produces broken symlinks with the target component stripped away
tar cf - -C /mnt . | tar tvf -
# drwxr-xr-x 0 root wheel 0 27 Okt. 05:41 ./
# lrwxr-xr-x 0 root wheel 0 27 Okt. 05:41 ./symlink-1 ->
# lrwxr-xr-x 0 root wheel 0 27 Okt. 05:41 ./symlink-2 ->
# lrwxr-xr-x 0 root wheel 0 27 Okt. 05:41 ./symlink-3 ->
# Produces intact symlinks (directly from ISO device or image)
tar tvf /dev/iso9660/TARPIT
tar tvf /tmp/tarpit.iso
# drwxr-xr-x 2 0 0 2048 27 Okt. 05:41 .
# lrwxr-xr-x 1 0 0 0 27 Okt. 05:41 symlink-1 -> /some/fqfn
# lrwxr-xr-x 1 0 0 0 27 Okt. 05:41 symlink-2 -> ../relpath
# lrwxr-xr-x 1 0 0 0 27 Okt. 05:41 symlink-3 -> symlink-1
# Cleanup
umount /mnt
mdconfig -d -u "${dev#md}"
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