build: Put system bus socket in runstatedir by default

This lets OS distributors configure --runstatedir=/run if they want to,
although for interoperability, they should only do this if they can
guarantee that their /run and /var/run are equivalent.

A previous commit adds a warning if we are using the default path on a
system where /run and /var/run are not synoymous, mitigating the
compatibility impact of this change.

For CMake, this requires version 3.9, released in 2017.

For Meson, this is currently controlled by the runtime_dir option,
which defaults to /run if the prefix is /usr. The rationale for this
is that /run is correct for modern Unix systems, and distributors who
switch from Autotools or CMake to Meson need to review all their build
options at that time, which is an ideal opportunity to check that they
are doing the right thing around /run.

Helps: https://gitlab.freedesktop.org/dbus/dbus/-/issues/180
Co-authored-by: Simon McVittie <smcv@collabora.com>

5 files changed, 7 insertions, 17 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6996f61e..2dd95e98 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.4)
+cmake_minimum_required(VERSION 3.9)
 
 # we do not need to have WIN32 defined
 set(CMAKE_LEGACY_CYGWIN_WIN32 0)
@@ -71,7 +71,7 @@ set(DBUS_MACHINE_UUID_FILE   ${CMAKE_INSTALL_FULL_LOCALSTATEDIR}/lib/dbus/machin
 set(DBUS_BINDIR              ${CMAKE_INSTALL_FULL_BINDIR})
 set(DBUS_DAEMONDIR           ${CMAKE_INSTALL_FULL_BINDIR})
 set(DBUS_LOCALSTATEDIR       ${CMAKE_INSTALL_FULL_LOCALSTATEDIR})
-set(DBUS_RUNSTATEDIR         ${CMAKE_INSTALL_FULL_LOCALSTATEDIR}/run)
+set(DBUS_RUNSTATEDIR         ${CMAKE_INSTALL_FULL_RUNSTATEDIR})
 
 # On Windows this is relative to where we put the bus setup, in
 # ${datadir}/dbus-1. For simplicity, we only do this if
diff --git a/bus/Makefile.am b/bus/Makefile.am
index 51a8de81..1f5017c5 100644
--- a/bus/Makefile.am
+++ b/bus/Makefile.am
@@ -185,7 +185,7 @@ install-data-hook:
 	$(mkinstalldirs) $(DESTDIR)$(dbusdatadir)/session.d
 	$(mkinstalldirs) $(DESTDIR)$(dbusdatadir)/services
 if DBUS_UNIX
-	$(mkinstalldirs) $(DESTDIR)$(localstatedir)/run/dbus
+	$(mkinstalldirs) $(DESTDIR)$(runstatedir)/dbus
 	$(mkinstalldirs) $(DESTDIR)$(dbusdatadir)/system.d
 	$(mkinstalldirs) $(DESTDIR)$(dbusdatadir)/system-services
 endif
diff --git a/bus/meson.build b/bus/meson.build
index 1aaaf48d..058e3b25 100644
--- a/bus/meson.build
+++ b/bus/meson.build
@@ -191,7 +191,7 @@ install_emptydirs += [
 
 if platform_unix
     install_emptydirs += [
-        get_option('localstatedir') / 'run' / 'dbus',
+        runstatedir / 'dbus',
         get_option('datadir') / 'dbus-1' / 'system.d',
         get_option('datadir') / 'dbus-1' / 'system-services',
     ]
diff --git a/configure.ac b/configure.ac
index ca704344..7da53d5d 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1331,14 +1331,9 @@ AC_SUBST([systemduserunitdir], [$with_systemduserunitdir])
 
 ##### Set up location for system bus socket
 
-AS_IF([! test -z "$with_system_socket"],
+AS_IF([test -n "$with_system_socket"],
    [DBUS_SYSTEM_SOCKET=$with_system_socket],
-   [
-   # We don't use runstatedir for this (yet?), because /var/run has been the
-   # interoperable system bus socket for 10+ years.
-   # See https://bugs.freedesktop.org/show_bug.cgi?id=101628
-   DBUS_SYSTEM_SOCKET=${EXPANDED_LOCALSTATEDIR}/run/dbus/system_bus_socket
-   ])
+   [DBUS_SYSTEM_SOCKET=${EXPANDED_RUNSTATEDIR}/dbus/system_bus_socket])
 
 dnl The actual check script is shared between Autotools and CMake.
 AS_IF([test "$dbus_win" != yes],
diff --git a/meson.build b/meson.build
index caaaccf2..33294e2e 100644
--- a/meson.build
+++ b/meson.build
@@ -822,13 +822,8 @@ config.set_quoted('DBUS_SESSION_CONFIG_FILE',
 
 system_socket = get_option('system_socket')
 if system_socket == ''
-    # We don't use runstatedir for this (yet?), because /var/run has been the
-    # interoperable system bus socket for 10+ years.
-    # See https://bugs.freedesktop.org/show_bug.cgi?id=101628
     system_socket = (
-        get_option('prefix')
-        / get_option('localstatedir')
-        /'run'/'dbus'/'system_bus_socket'
+        get_option('prefix') / runstatedir / 'dbus' / 'system_bus_socket'
     )
 endif