File system layout

Installation paths

PG:

0201

Source:

QA

Reference:

https://gitweb.gentoo.org/repo/gentoo.git/tree/metadata/install-qa-check.d/08gentoo-paths

Reported:

via install-qa-check.d

Gentoo packages may only install into one of the following top-level directories:

  • /bin

  • /boot

  • /dev

  • /etc

  • /lib*

  • /opt

  • /sbin

  • /srv

  • /usr

  • /var

Furthermore, only the following subdirectories of /usr are permitted:

  • /usr/bin

  • /usr/include

  • /usr/lib*

  • /usr/libexec

  • /usr/sbin

  • /usr/share

  • /usr/src

  • /usr/<triplet>

Furthermore, within /usr/share/doc hierarchy only a subdirectory named after full package name and version with revision (PF) is permitted.

In the aforementioned lists, ‘lib*’ indicates lib and its appropriate suffixed variants for the architecture in question. ‘<triplet>’ indicates either CHOST or CTARGET value, as used by toolchain packages.

Additional exceptions can be granted by the QA team. Currently those exceptions are:

  • /gnu for the guix package manager

  • /nix for the nix package manager

Support for separate /usr

PG:

0202

Source:

QA

Reference:

https://projects.gentoo.org/council/meeting-logs/20130813-summary.txt https://projects.gentoo.org/council/meeting-logs/20130924-summary.txt

Reported:

no

Developers are not required to support using separate /usr filesystem without an initramfs.

Rationale: upstream software (as of 2013) is already making support for early boot without /usr mounted difficult, and whenever it is still works, it is either subtly broken or relying on hacks (udev). In setups using initramfs, some of the boot and repair functionality can be moved from rootfs to initramfs.

Strict multilib layout

PG:

0203

Source:

QA

Reference:

https://gitweb.gentoo.org/proj/portage.git/tree/bin/install-qa-check.d/80multilib-strict

Reported:

via install-qa-check.d, fatal

Libraries must be installed into an appropriate /lib* or /usr/lib* directory corresponding to their ABI. For example, 64-bit libraries on amd64 must be installed into lib64 and not lib.

Libraries installed as a part of larger software package can be installed along with it into a subdirectory of lib.

Rationale: historically, Gentoo has been symlinking /lib to /lib64 in order to maintain compatibility with old packages hardcoding /lib path. With modern Gentoo profiles, this is no longer the case and packages must install libraries into appropriate directory for them to be correctly found by the dynamic loader.

Static libraries and libtool files

PG:

0204

Source:

QA

Reference:

https://gitweb.gentoo.org/proj/portage.git/tree/bin/install-qa-check.d/80libraries

Reported:

via install-qa-check.d, fatal

Static libraries and libtool files (.la) must be installed into /usr hierarchy and never to root filesystem (/lib*). If an additional shared version of the library is installed to /lib*, a .so linker script must be installed into /usr/lib* in order to ensure correct linking.

Rationale: historically, the purpose of root filesystem was to hold files strictly needed at boot. For this reason, many old Gentoo installations may still use small / partition. Static libraries are used only during package builds, and installing them to rootfs would be a waste of space.

Game install locations and ownership

PG:

0205

Source:

Council, clarified by QA

Reference:

https://projects.gentoo.org/council/meeting-logs/20151213-summary.txt https://projects.gentoo.org/council/meeting-logs/20151011-summary.txt

Reported:

via install-qa-check.d

The historical game install locations (/usr/games and /etc/games) must not be used anymore. Instead, games should follow normal guidelines for install locations. As an exception, /usr/share/games can be used if this location is used upstream, and /var/games can be used for shared game files (e.g. high scores, game state files).

The historical games group must no longer be used. Games must work for users that are not in this group. The aforementioned install locations must therefore be owned by root and be world-readable.

If games need privileged access to shared files, the group gamestat can be used for this purpose. The game executables should be owned by that group and made setgid. The shared files must be installed into /var/games hierarchy, and writable to gamestat group.

Rationale: there is no technical reason to isolate games from other applications on the system, or to restrict access to them. The boundary between game and non-game packages is very blurry on modern systems, especially due to web browsers.

The historical use of games group on Gentoo to control access is inconsistent with the use in other distributions where it was used to share data files. Since the latter implied users must not be added to the games group, a new group (gamestat) needed to be created to fulfill that purpose.

Absolute symbolic link targets

PG:

0206

Source:

QA

Reported:

by repoman and pkgcheck (when ebuild-generated)

Packages must not install symbolic links with absolute targets. Instead, relative paths must be used. An exception is granted for symlinks to specially mounted filesystems (such as /proc, /run) when symlinks are supposed to always reference the running host system.

Example:

# BAD:
dosym /usr/lib/frobnicate/frobnicate /usr/bin/frobnicate
# GOOD:
dosym ../lib/frobnicate/frobnicate /usr/bin/frobnicate
# ACCEPTABLE EXCEPTION:
dosym /proc/self/mounts /etc/mtab

Rationale: absolute symlinks work correctly only when the root filesystem is mounted at /. They point at the wrong location whenever it is mounted in another location, e.g. for the purposes of recovery.