format for OpenBSD binary
Binary packages for OpenBSD
can be created using
and are usually manipulated using
The basic underlying format is an archive following the ustar specification that
can be handled with
Package names always end in “.tgz”; the file name itself should
Note that the base distribution tarballs of OpenBSD
, ...) are not binary packages
fit for pkg_add(1)
All types of archive contents can be present in a package, including files,
directories, hardlinks, symlinks, fifos, block and character devices.
In order to allow just-in-time extraction, packages always begin with a table of
contents, named +CONTENTS
. This table of
contents can be read using the API described in
All the remaining information in the archive should be referenced in the
packing-list, including all relevant information: symlinks destinations,
special permissions, and file owners. See
for annotation details.
This table of contents is always followed by a few special files, some of which
are optional: the package description (+DESC), a display message (+DISPLAY),
The ustar format has some limitations with respect to file names. Accordingly,
the package tools will replace very long names with
and long link names with
. The packing-list will hold the
real file names, and the package tools will reconstitute the correct names
behind the scenes.
All information within a package is checksummed, using SHA256 since
. During creation and installation,
meta-information, such as file owners and permissions, are also checked: any
important stuff that isn't recorded in the packing-list is an error.
Packing-lists can be signed. If a signature is found, then it will be checked
during installation, and failure to verify will prevent the package from
installing correctly. Currently, only X.509-style signatures are supported.
They rely on a certificate authority file being present as
and all signatures will
be checked against it. Once the packing-list signature is checked, all
individual packing elements will be checksummed, resulting in a
‘just-in-time’ signature checking.
Fat packages were removed in OpenBSD 5.1
, since no
practical application was found.
Packages are valid gzip'ed ustar archives that can be extracted using
. In particular,
hardlink names should be valid, and all items will extract to different names.
However, it may be a bit difficult to make sense of the package contents
without peeking at the packing-list.