Merge branch 'autoconf-runstatedir' into 'master'

Use ${runstatedir} for system bus instead of ${localstatedir}/run

Closes #180

See merge request dbus/dbus!209

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
@@ -599,6 +599,18 @@ set(DBUS_SYSTEM_PID_FILE ${DBUS_RUNSTATEDIR}/dbus/pid)
 # address.
 set(DBUS_SYSTEM_BUS_DEFAULT_ADDRESS "unix:path=${DBUS_RUNSTATEDIR}/dbus/system_bus_socket" CACHE STRING "system bus default address")
 
+# This check assumes that the disposition of /run and /var/run on the
+# system where we're building is the same as on the system we're building
+# for, so we can't usefully do this check if we're building for Windows,
+# or if we're cross-building for Unix on a Windows machine.
+#
+# The check is shared between Autotools and CMake.
+# Because we only run it on Unix, it's fine to make it a shell script.
+if(UNIX AND (NOT CMAKE_HOST_SYSTEM_NAME STREQUAL "Windows"))
+    execute_process(
+        COMMAND "${CMAKE_SOURCE_DIR}/tools/check-runstatedir.sh" "${DBUS_RUNSTATEDIR}/dbus/system_bus_socket")
+endif()
+
 if(WIN32)
     set(DBUS_SESSION_BUS_LISTEN_ADDRESS "autolaunch:" CACHE STRING "session bus default listening address")
     set(DBUS_SESSION_BUS_CONNECT_ADDRESS "autolaunch:" CACHE STRING "session bus fallback address for clients")

Makefile.am

@@ -37,6 +37,7 @@ EXTRA_DIST =			\
 	test/CMakeLists.txt \
 	test/name-test/CMakeLists.txt \
 	tools/CMakeLists.txt \
+	tools/check-runstatedir.sh \
 	cmake \
 	$(NULL)
 

NEWS

@@ -1,6 +1,31 @@
 dbus 1.15.4 (UNRELEASED)
 ========================
 
+Dependencies:
+
+• Building with CMake now requires CMake ≥ 3.9.
+
+Build-time configuration changes:
+
+• On Unix platforms, a path in the runtime state directory (often /run)
+  is now used for the well-known system bus socket by default. OS
+  distributors should check that the path used is equivalent to the
+  interoperable path /var/run/dbus/system_bus_socket, especially if
+  running on an OS where /var/run is not guaranteed to be a symbolic
+  link to /run.
+  (dbus#180; Issam E. Maghni, Simon McVittie)
+  · With Autotools, this is controlled by --runstatedir, which defaults
+    to ${localstatedir}/run but is often set to /run by OS distributors.
+    The path to the system bus socket can be overridden with the
+    --with-system-socket option if required.
+  · With CMake, this is controlled by the RUNSTATEDIR option, which has
+    behaviour similar to Autotools. There is no separate option for the
+    path to the system bus socket.
+  · With Meson, this is controlled by the runtime_dir option, which
+    defaults to /run if the installation prefix is set to /usr, or has
+    behaviour similar to Autotools otherwise. The path to the system bus
+    socket can be overridden with the system_socket option if required.
+
 New API:
 
 • Add dbus_connection_set_builtin_filters_enabled(), intended to be called

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

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',
     ]

configure.ac

@@ -1286,8 +1286,8 @@ AM_CONDITIONAL(DBUS_CAN_UPLOAD_DOCS,
     [test x$enable_doxygen_docs = xyes && test x$enable_xml_docs = xyes &&
      test x$enable_ducktype_docs = xyes])
 
-# Autoconf 2.70 will support this, and many distros patch this option in,
-# but Autoconf 2.70 hasn't actually been released yet.
+# Autoconf 2.70 supports this, and many distros patched this option in
+# before Autoconf 2.70 was released
 AS_IF([test -z "${runstatedir}"], [runstatedir='${localstatedir}/run'])
 AC_SUBST([runstatedir])
 
@@ -1330,14 +1330,14 @@ AS_HELP_STRING([--with-systemduserunitdir=DIR], [Directory for systemd user serv
 AC_SUBST([systemduserunitdir], [$with_systemduserunitdir])
 
 ##### Set up location for system bus socket
-if ! test -z "$with_system_socket"; then
-   DBUS_SYSTEM_SOCKET=$with_system_socket
-else
-   # 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=${EXPANDED_LOCALSTATEDIR}/run/dbus/system_bus_socket
-fi
+
+AS_IF([test -n "$with_system_socket"],
+   [DBUS_SYSTEM_SOCKET=$with_system_socket],
+   [DBUS_SYSTEM_SOCKET=${EXPANDED_RUNSTATEDIR}/dbus/system_bus_socket])
+
+dnl The actual check script is shared between Autotools and CMake.
+AS_IF([test "$dbus_win" != yes],
+    [${CONFIG_SHELL-/bin/sh} "${srcdir}/tools/check-runstatedir.sh" "$DBUS_SYSTEM_SOCKET"])
 
 AC_SUBST(DBUS_SYSTEM_SOCKET)
 AC_DEFINE_UNQUOTED(DBUS_SYSTEM_SOCKET,"$DBUS_SYSTEM_SOCKET",[The name of the socket the system bus listens on by default])

doc/dbus-specification.xml

@@ -5783,13 +5783,27 @@
           variable. If that variable is not set, applications should try
           to connect to the well-known address
           <literal>unix:path=/var/run/dbus/system_bus_socket</literal>.
-          <footnote>
-            <para>
-              The D-Bus reference implementation actually honors the
-              <literal>$(localstatedir)</literal> configure option
-              for this address, on both client and server side.
-            </para>
-          </footnote>
+          Implementations of the well-known system bus should listen on
+          an address that will result in that connection being successful.
+        </para>
+        <para>
+          On systems where <filename>/var/run/</filename> is known to be
+          synonymous with <filename>/run/</filename> (such as most Linux
+          operating system distributions), implementations might prefer
+          to make use of that knowledge to connect to or listen on
+          <literal>unix:path=/run/dbus/system_bus_socket</literal> instead,
+          which has some minor technical advantages, particularly during
+          early startup and late shutdown.
+        </para>
+        <para>
+          In practice, implementations of D-Bus often have build-time
+          configuration options for the system bus address, whose defaults
+          often depend on other build-time options such as the installation
+          prefix (in particular, this is the case for dbus, the reference
+          implementation of D-Bus).
+          Distributors intending to provide access to the well-known
+          system bus should verify that they are using an interoperable
+          address.
         </para>
         <para>
           On Unix systems, the system bus should default to searching

meson.build

@@ -822,15 +822,29 @@ 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
+
+# This check assumes that the disposition of /run and /var/run on the
+# system where we're building is the same as on the system we're building
+# for, so we can't usefully do this check if we're building for Windows,
+# or if we're cross-building for Unix on a Windows machine.
+#
+# The check is shared between Autotools, CMake and Meson.
+# Because we only run it on Unix, it's fine to make it a shell script.
+if platform_unix and build_machine.system() != 'windows'
+    msg = run_command(
+        find_program('tools/check-runstatedir.sh'),
+        system_socket,
+        check: false,
+    ).stdout()
+    if msg != ''
+        warning(msg)
+    endif
+endif
+
 data_config.set('DBUS_SYSTEM_SOCKET', system_socket)
 
 ## System bus only listens on local domain sockets, and never

tools/check-runstatedir.sh

@@ -0,0 +1,77 @@
+#!/bin/sh
+# Copyright 2022 Collabora Ltd.
+# SPDX-License-Identifier: MIT
+
+# Usage: check-runstatedir.sh /run/dbus/system_bus_socket
+
+set -e
+set -u
+
+same_file () {
+    # Many shells implement test -ef (test whether two names point to
+    # the same file), but POSIX doesn't require it, so fall back to
+    # comparing realpath output if necessary. We prefer test -ef if
+    # available, since it does the right thing for bind-mounts, not just
+    # symlinks
+    if test / -ef / 2>/dev/null; then
+        test  "$1" -ef "$2"
+    else
+        test "$(realpath "$1")" = "$(realpath "$2")"
+    fi
+}
+
+if [ -e /run ] && [ -e /var/run ] && ! same_file /run /var/run; then
+    echo
+    echo "WARNING: /run and /var/run are not the same directory."
+    echo "| Tools that do not agree on whether a socket is in /run or in"
+    echo "| /var/run will fail to interoperate."
+    echo "| Ask your OS distributor to make these two directories equivalent"
+    echo "| via a symbolic link or bind mount: there is no useful reason to"
+    echo "| make them different."
+    echo
+fi
+
+system_socket="$1"
+
+case "$system_socket" in
+    (/run/dbus/system_bus_socket)
+        # --with-system-socket=/run/dbus/system_bus_socket
+        if ! same_file /run /var/run; then
+            echo
+            echo "WARNING: system bus socket: /run/dbus/system_bus_socket"
+            echo "| The system bus has been configured to listen on"
+            echo "| /run/dbus/system_bus_socket, but /run is not the same"
+            echo "| as /var/run on this system."
+            echo "|"
+            echo "| Most D-Bus implementations will expect to find the D-Bus"
+            echo "| system bus socket at /var/run/dbus/system_bus_socket."
+            echo "| Consider creating a symbolic link."
+            echo
+        fi
+        ;;
+
+    (/var/run/dbus/system_bus_socket)
+        # e.g. --localstatedir=/var
+        if ! same_file /run /var/run; then
+            echo
+            echo "NOTE: system bus socket: /var/run/dbus/system_bus_socket"
+            echo "| The system bus has been configured to listen on"
+            echo "| /var/run/dbus/system_bus_socket, but /run is not the same"
+            echo "| as /var/run on this system."
+            echo "|"
+            echo "| Some D-Bus implementations might expect to find the"
+            echo "| D-Bus system bus socket at /run/dbus/system_bus_socket."
+            echo "| Consider creating a symbolic link."
+            echo
+        fi
+        ;;
+
+    (*)
+        # e.g. --prefix=/opt/dbus
+        echo
+        echo "NOTE: system bus listens on $system_socket"
+        echo "| This build of dbus will not interoperate with the well-known"
+        echo "| system bus socket, /var/run/dbus/system_bus_socket."
+        echo
+        ;;
+esac