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From 254338a838354d9d3e43efa14190ca1203ef3afe Mon Sep 17 00:00:00 2001
Zbigniew Jędrzejewski-Szmek 1cc4f8
From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
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Date: Wed, 3 Jul 2024 17:05:31 +0200
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Subject: [PATCH 3/3] meson: add option to build systemd-executor "statically"
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The new link-executor-shared option is similar to the existing
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link-udev-shared: when set to false, we link to the static versions of our
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internal libraries.
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The resulting exuctor binary is fairly large, about as large as libsystemd-core
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(14 MB without lto, 8 with lto).
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This is intended as a workaround for the fuckup with the pinned executor
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binary:
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when an upgrade is performed, the package manager will install new version of
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the libraries and new version of the code, and some time later reexecute the
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managers. This creates a window when the pinned executor binary will fail to
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execute. There are two factors which make the issue easier to hit:
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- when the distribution uses a finely-grained shared-lib-tag. E.g. Fedora
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  uses version-release as the tag, which means that the issue occurs on
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  every package upgrade. This is the right thing to do, because the
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  ABI of our internal libraries is not stable at all, so replacing the
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  library from a different version in place creates a window where our
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  programs may crash or misbehave.
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- when the distribution doesn't immediately reexec all the managers after
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  upgrade. In early versions of systemd, we used to hammer the machine during
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  upgrade, doing daemon-reexecs repeatedly. This works, but is ugly and
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  wasteful. Doing the reexecs while the upgrade is in progres also creates a
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  window where a mix of old and new configs or both is loaded. Users are
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  particularly annoyed by those reloads if there is some issue in the
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  configuration causing us to emit warnings on every reexec. Doing the
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  reexecs once after the new configuration and libraries have been put
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  in place is nicer.
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The pinning of the executor binary breaks upgrades and in particular
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it penalizes the distributions which make use of the features which
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were previously added to avoid bugs and inefficiency during upgrades.
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When the executor is linked statically, there is a smaller chance that it'll
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fail to load libraries. The issue can still occur because other libraries, not
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our own, are linked dynamically.
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(cherry picked from commit d59cae6cebd0fc25a16a020bd28e5303901f1b19)
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---
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 meson_options.txt    |  2 ++
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 src/core/meson.build | 16 ++++++++++++----
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 2 files changed, 14 insertions(+), 4 deletions(-)
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diff --git a/meson_options.txt b/meson_options.txt
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index 667340ca59..909e2d53e8 100644
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--- a/meson_options.txt
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+++ b/meson_options.txt
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@@ -21,6 +21,8 @@ option('rootprefix', type : 'string', deprecated: true,
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        description : 'This option is deprecated and will be removed in a future release')
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 option('link-udev-shared', type : 'boolean',
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        description : 'link systemd-udevd and its helpers to libsystemd-shared.so')
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+option('link-executor-shared', type : 'boolean',
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+       description : 'link systemd-executor to libsystemd-shared.so and libsystemd-core.so')
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 option('link-systemctl-shared', type: 'boolean',
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        description : 'link systemctl against libsystemd-shared.so')
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 option('link-networkd-shared', type: 'boolean',
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diff --git a/src/core/meson.build b/src/core/meson.build
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index 1ef31cc529..dbeb752977 100644
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--- a/src/core/meson.build
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+++ b/src/core/meson.build
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@@ -156,6 +156,17 @@ systemd_executor_sources = files(
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         'exec-invoke.c',
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 )
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+executor_libs = get_option('link-executor-shared') ? \
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+        [
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+                libcore,
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+                libshared,
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+        ] : [
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+                libcore_static,
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+                libshared_static,
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+                libbasic_static,
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+                libsystemd_static,
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+        ]
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+
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 executables += [
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         libexec_template + {
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                 'name' : 'systemd',
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@@ -173,10 +184,7 @@ executables += [
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                 'public' : true,
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                 'sources' : systemd_executor_sources,
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                 'include_directories' : core_includes,
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-                'link_with' : [
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-                        libcore,
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-                        libshared,
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-                ],
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+                'link_with' : executor_libs,
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                 'dependencies' : [
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                         libapparmor,
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                         libpam,