NAME
package
,
packing-list
, plist
—
format for OpenBSD binary packages and
packing-lists
DESCRIPTION
Binary packages for OpenBSD can be created using pkg_create(1) and are usually manipulated using pkg_add(1), pkg_mklocatedb(1), or pkg_info(1).
The basic underlying format is an archive following the ustar specification that can be handled with tar(1) and compressed using gzip(1).
Package names always end in “.tgz”; the file name itself should conform to packages-specs(7).
Note that the base distribution tarballs of OpenBSD (e.g. baseXX.tgz, compXX.tgz, ...) 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, nicknamed
packing-list
(plist
for
short). This table of contents can be read using the API described in
OpenBSD::PackingList(3p).
All the remaining information in the archive should be referenced
in the packing-list
, including symlinks
destinations, special permissions, and file owners
(pkg_create(1) and
pkg_add(1) actually enforce this). See
pkg_create(1) 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), etc.
The basic ustar format has some limitations with respect to file names. Packages now use the "extended record specification" (header type x) for long links and long file names. Other extended ustar headers are currently recognized, but not supported.
Starting with OpenBSD 5.5, the compressed archive may be composed of several gzip(1) archives concatenated together. gzip(1) doesn't mind, and tar(1) is happy as long as the uncompressed stream is sane. This allows for faster signing and better rsync properties.
Starting with OpenBSD 5.6, tarballs are
stored "out-of-order": each archive entry will match an entry in
the packing-list
(and all file-like entries will be
matched), but the order will be adjusted so that most recently changed files
come first, in order to allow faster updates.
Starting with OpenBSD 5.7, by default,
timestamps are stored directly in the packing-list
as @ts
annotations. The files in the archive will
have a null timestamp.
The combination of the LRU archive order, null timestamps and compression in fixed chunks starting from the end, means a substantial amount of data doesn't change from snapshot to snapshot, thus reducing the pressure on mirroring bandwidth.
PACKING LIST ANNOTATIONS
User annotations are described in pkg_create(1). The following annotations are automatically inserted during package creation and installation:
@arch
arches- List of architectures for which this package is intended. This corresponds
to
-A
arches of pkg_create(1) @comment pkgpath=path ftp=yes/no
- Historical accident. This specific comment encodes the actual
-D
FULLPKGPATH, and-D
FTP arguments to pkg_create(1). @depend
pkgpath:pkgspec:default- Record a dependency declared using the option
-P
of pkg_create(1). @digital-signature
signify2:date:external- Record the date of signature of a package, synthesized by pkg_add(1) from signify(1) output.
@link
name- Added after a file entry by
package
to record that the entry is actually a hard link. @localbase
base- Used internally to record the settings of
-L
option. @name
pkgname- Set the name of the package. This name is potentially different than the name of the file it came in, and is used when keeping track of the package for later deinstallation. pkg_create(1) will derive this field from the package file name.
@option
name- Some options are automatically inserted/modified by the package tools:
- always-update
- pkg_create(1) will complete the option line with a sha256
digest of the whole
packing-list
encoded in base64. - firmware
- Set by fw_update(8) to trigger firmware-specific handling. In particular, firmware is hidden from normal updates.
- manual-installation
- Record that a package has been explicitly installed by the user, and
not as a result of a dependency look-up. Refer to
pkg_add(1)'s
-a
option for details.
@sha
- Added after a file entry by pkg_create(1) to record the files's cryptographic checksum, as a sha256 digest encoded in base64.
@signer
- Record the signing key for a package, synthesized by pkg_add(1) from signify(1) output.
@size
- Added after a file entry by pkg_create(1) to record a file size.
@symlink
name- Added after a file entry by pkg_create(1) to record that the entry is actually a symbolic link.
@url
- Original location of the package, synthesized by pkg_add(1) during installation.
@ts
timestamp- Added after a file entry to record the actual file timestamp, instead of storing it as tarball meta-info. The package tools read and process that annotation correctly, whereas tar(1) will only see files dated from the epoch.
@version
number- Record a global (system) version number for the package. This is built
adding together
-V
options from pkg_create(1), and triggers updates when it changes. @wantlib
libspec- Record a library requirement declared using the option
-W
of pkg_create(1).
Note that most of these annotations cannot be added manually, as pkg_create(1) will error out.
PACKAGE SIGNATURES
All information within a package is checksummed, using SHA256
since OpenBSD 4.4. 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.
Starting with OpenBSD 6.1,
signify(1) -zS
gzip(1) header
signatures are the only supported format. This allows for
‘just-in-time’ signature checking, as the binary data is
checked in 64K bytes long chunks.
SEE ALSO
pkg_add(1), pkg_create(1), pkg_info(1), pkg_sign(1), packages(7), packages-specs(7)
STANDARDS
Packages are valid gzip'ed ustar archives that can be extracted
using tar(1). 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
.