sd_notify (systemd status notifications) support

sd_notify() is used to notify systemd of changes to the status of the
process. This allows the systemd daemon to know when the process
finished loading (and thus only start another program after Asterisk has
finished loading).

To use this, use a systemd unit with 'Type=notify' for Asterisk.

This commit also adds the function ast_sd_notify(), a wrapper around
sd_notify that does nothing if not built with systemd support.

Also adds support for libsystemd detection in the configure script.

Change-Id: Ied6a59dafd5ef331c5c7ae8f3ccd2dfc94be7811

configure

@@ -639,6 +639,11 @@ PBX_SYSLOG_FACILITY_LOG_DAEMON
 PBX_SYSLOG_FACILITY_LOG_CRON
 PBX_SYSLOG_FACILITY_LOG_AUTHPRIV
 PBX_SYSLOG_FACILITY_LOG_AUTH
+SYSTEMD_LIBS
+SYSTEMD_CFLAGS
+SYSTEMD_INCLUDE
+SYSTEMD_LIB
+PBX_SYSTEMD
 PBX_GENERIC_ODBC
 GENERIC_ODBC_INCLUDE
 GENERIC_ODBC_LIB
@@ -1320,6 +1325,7 @@ infodir
 docdir
 oldincludedir
 includedir
+runstatedir
 localstatedir
 sharedstatedir
 sysconfdir
@@ -1460,7 +1466,9 @@ PYTHONDEV_LIBS
 GMIME_CFLAGS
 GMIME_LIBS
 GTK2_CFLAGS
-GTK2_LIBS'
+GTK2_LIBS
+SYSTEMD_CFLAGS
+SYSTEMD_LIBS'
 
 
 # Initialize some variables set by options.
@@ -1499,6 +1507,7 @@ datadir='${datarootdir}'
 sysconfdir='${prefix}/etc'
 sharedstatedir='${prefix}/com'
 localstatedir='${prefix}/var'
+runstatedir='${localstatedir}/run'
 includedir='${prefix}/include'
 oldincludedir='/usr/include'
 docdir='${datarootdir}/doc/${PACKAGE_TARNAME}'
@@ -1751,6 +1760,15 @@ do
   | -silent | --silent | --silen | --sile | --sil)
     silent=yes ;;
 
+  -runstatedir | --runstatedir | --runstatedi | --runstated \
+  | --runstate | --runstat | --runsta | --runst | --runs \
+  | --run | --ru | --r)
+    ac_prev=runstatedir ;;
+  -runstatedir=* | --runstatedir=* | --runstatedi=* | --runstated=* \
+  | --runstate=* | --runstat=* | --runsta=* | --runst=* | --runs=* \
+  | --run=* | --ru=* | --r=*)
+    runstatedir=$ac_optarg ;;
+
   -sbindir | --sbindir | --sbindi | --sbind | --sbin | --sbi | --sb)
     ac_prev=sbindir ;;
   -sbindir=* | --sbindir=* | --sbindi=* | --sbind=* | --sbin=* \
@@ -1888,7 +1906,7 @@ fi
 for ac_var in	exec_prefix prefix bindir sbindir libexecdir datarootdir \
 		datadir sysconfdir sharedstatedir localstatedir includedir \
 		oldincludedir docdir infodir htmldir dvidir pdfdir psdir \
-		libdir localedir mandir
+		libdir localedir mandir runstatedir
 do
   eval ac_val=\$$ac_var
   # Remove trailing slashes.
@@ -2041,6 +2059,7 @@ Fine tuning of the installation directories:
   --sysconfdir=DIR        read-only single-machine data [PREFIX/etc]
   --sharedstatedir=DIR    modifiable architecture-independent data [PREFIX/com]
   --localstatedir=DIR     modifiable single-machine data [PREFIX/var]
+  --runstatedir=DIR       modifiable per-process data [LOCALSTATEDIR/run]
   --libdir=DIR            object code libraries [EPREFIX/lib]
   --includedir=DIR        C header files [PREFIX/include]
   --oldincludedir=DIR     C header files for non-gcc [/usr/include]
@@ -2213,6 +2232,10 @@ Some influential environment variables:
   GMIME_LIBS  linker flags for GMIME, overriding pkg-config
   GTK2_CFLAGS C compiler flags for GTK2, overriding pkg-config
   GTK2_LIBS   linker flags for GTK2, overriding pkg-config
+  SYSTEMD_CFLAGS
+              C compiler flags for SYSTEMD, overriding pkg-config
+  SYSTEMD_LIBS
+              linker flags for SYSTEMD, overriding pkg-config
 
 Use these variables to override the choices made by `configure' or to help
 it to find libraries and programs with nonstandard names/locations.
@@ -34811,6 +34834,98 @@ fi
 
 
 
+
+
+
+
+   if test "x${PBX_SYSTEMD}" != "x1" -a "${USE_SYSTEMD}" != "no"; then
+
+pkg_failed=no
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for SYSTEMD" >&5
+$as_echo_n "checking for SYSTEMD... " >&6; }
+
+if test -n "$SYSTEMD_CFLAGS"; then
+    pkg_cv_SYSTEMD_CFLAGS="$SYSTEMD_CFLAGS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libsystemd\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "libsystemd") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_SYSTEMD_CFLAGS=`$PKG_CONFIG --cflags "libsystemd" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+if test -n "$SYSTEMD_LIBS"; then
+    pkg_cv_SYSTEMD_LIBS="$SYSTEMD_LIBS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"libsystemd\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "libsystemd") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_SYSTEMD_LIBS=`$PKG_CONFIG --libs "libsystemd" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+
+
+
+if test $pkg_failed = yes; then
+   	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+
+if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
+        _pkg_short_errors_supported=yes
+else
+        _pkg_short_errors_supported=no
+fi
+        if test $_pkg_short_errors_supported = yes; then
+	        SYSTEMD_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "libsystemd" 2>&1`
+        else
+	        SYSTEMD_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "libsystemd" 2>&1`
+        fi
+	# Put the nasty error message in config.log where it belongs
+	echo "$SYSTEMD_PKG_ERRORS" >&5
+
+
+            PBX_SYSTEMD=0
+
+
+elif test $pkg_failed = untried; then
+     	{ $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+
+            PBX_SYSTEMD=0
+
+
+else
+	SYSTEMD_CFLAGS=$pkg_cv_SYSTEMD_CFLAGS
+	SYSTEMD_LIBS=$pkg_cv_SYSTEMD_LIBS
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+
+            PBX_SYSTEMD=1
+            SYSTEMD_INCLUDE="$SYSTEMD_CFLAGS"
+            SYSTEMD_LIB="$SYSTEMD_LIBS"
+
+$as_echo "#define HAVE_SYSTEMD 1" >>confdefs.h
+
+
+fi
+   fi
+
+
 PBX_SYSLOG=0
 
 if test "${ac_cv_header_syslog_h}" = "yes"; then