configure: Improve portability by not assuming every non-Windows, non-Darwin OSes have udev

udev is only available on Linux. Only enable it when it actually exists on
the host. The primary purpose of this change is to support NetBSD.

Author: depressed-pho

Makefile.am

@@ -1,6 +1,6 @@
 AUTOMAKE_OPTIONS = foreign
 ACLOCAL_AMFLAGS = -I m4
-SUBDIRS = src $(UDEV_SUB) $(SYSTEMD_SUB) docs
+SUBDIRS = src udev systemd docs
 
 EXTRA_DIST = \
 	docs \
@@ -10,4 +10,4 @@ EXTRA_DIST = \
 
 DISTCHECK_CONFIGURE_FLAGS = \
 	--with-udevrulesdir=$$dc_install_base/$(udevrulesdir) \
-	--with-systemdsystemunitdir=$$dc_install_base/$(systemdsystemunitdir)
+	--with-systemdsystemunitdir=$$dc_install_base/$(systemdsystemunitdir)

configure.ac

@@ -58,36 +58,61 @@ else
   fi
 fi
 
+AC_ARG_WITH([udev],
+            [AS_HELP_STRING([--with-udev],
+            [Build with udev support @<:@default=auto@:>@])],
+            [with_udev=$withval],
+            [with_udev=auto])
+if test "x$with_udev" = "xauto"; then
+  AC_MSG_CHECKING([for udev])
+  PKG_CHECK_EXISTS([udev],
+                   [AC_MSG_RESULT([yes])
+                    with_udev=yes],
+                   [AC_MSG_RESULT([no])])
+fi
+if test "x$with_udev" = "xyes"; then
+  AC_DEFINE([HAVE_UDEV], [1], [Define to enable udev support])
+fi
+
 AC_ARG_WITH([udevrulesdir],
             AS_HELP_STRING([--with-udevrulesdir=DIR],
-            [Directory for udev rules]),
+            [Directory for udev rules @<:@default=auto@:>@]),
             [],
             [with_udevrulesdir=auto])
 if test "x$with_udevrulesdir" = "xauto"; then
-  udevdir=$($PKG_CONFIG --variable=udevdir udev)
-  if test "x$udevdir" != "x"; then
-    with_udevrulesdir=$udevdir"/rules.d"
-  else
-    with_udevrulesdir=$prefix/lib/udev/rules.d
-  fi
+  PKG_CHECK_VAR([udevdir], [udev], [udevdir],
+                [with_udevrulesdir="${udevdir}/rules.d"],
+                [with_udevrulesdir="${libdir}/udev/rules.d"])
 fi
+AC_SUBST([udevrulesdir], [$with_udevrulesdir])
+AM_CONDITIONAL([WANT_UDEV], [test -n "$with_udevrulesdir" -a "x$with_udevrulesdir" != xno -a "x$with_udev" = "xyes"])
 
 AC_ARG_WITH([systemd],
-            [AS_HELP_STRING([--without-systemd],
-            [do not build with systemd support @<:@default=yes@:>@])],
+            [AS_HELP_STRING([--with-systemd],
+            [Build with systemd support @<:@default=auto@:>@])],
             [with_systemd=$withval],
-            [with_systemd=yes])
+            [with_systemd=auto])
+if test "x$with_systemd" = "xauto"; then
+  AC_MSG_CHECKING([for systemd])
+  PKG_CHECK_EXISTS([systemd],
+                   [AC_MSG_RESULT([yes])
+                    with_systemd=yes],
+                   [AC_MSG_RESULT([no])])
+fi
+if test "x$with_systemd" = "xyes"; then
+  AC_DEFINE([HAVE_SYSTEMD], [1], [Define to enable systemd support])
+fi
 
 AC_ARG_WITH([systemdsystemunitdir],
             [AS_HELP_STRING([--with-systemdsystemunitdir=DIR],
-            [directory for systemd service files])],
-            [with_systemdsystemunitdir=$withval],
-            [with_systemdsystemunitdir=$($PKG_CONFIG --variable=systemdsystemunitdir systemd)])
-
-if test "x$with_systemdsystemunitdir" != xno; then
-  AC_SUBST([systemdsystemunitdir], [$with_systemdsystemunitdir])
+            [Directory for systemd service files @<:@default=auto@:>@])],
+            [],
+            [with_systemdsystemunitdir=auto])
+if test "x$with_systemdsystemunitdir" = "xauto"; then
+  PKG_CHECK_VAR([with_systemdsystemunitdir], [systemd], [systemdsystemunitdir])
 fi
-AM_CONDITIONAL(WANT_SYSTEMD, [test -n "$with_systemdsystemunitdir" -a "x$with_systemdsystemunitdir" != xno -a "x$with_systemd" = "xyes" ])
+AC_SUBST([systemdsystemunitdir], [$with_systemdsystemunitdir])
+AM_CONDITIONAL([WANT_SYSTEMD], [test -n "$with_systemdsystemunitdir" -a "x$with_systemdsystemunitdir" != xno -a "x$with_systemd" = "xyes"])
 
 if test "x$with_systemd" = xyes; then
   udev_activation_rule="ENV{SYSTEMD_WANTS}=\"usbmuxd.service\""
@@ -116,8 +141,6 @@ AC_CHECK_FUNCS([ppoll clock_gettime localtime_r])
 
 # Check for operating system
 AC_MSG_CHECKING([whether to enable WIN32 build settings])
-UDEV_SUB=
-SYSTEMD_SUB=
 case ${host_os} in
   *mingw32*|*cygwin*)
     win32=true
@@ -135,24 +158,19 @@ case ${host_os} in
   *)
     win32=false
     AC_MSG_RESULT([no])
-    UDEV_SUB=udev
-    AC_SUBST([udevrulesdir], [$with_udevrulesdir])
-    AC_DEFINE(HAVE_UDEV, 1, [Define to enable udev support])
-    activation_method="systemd"
-    if test "x$with_systemd" != "xyes"; then
-      echo "*** Note: support for systemd activation has been disabled, using udev activation instead ***"
+    if test "x$with_udev" = "xyes"; then
       activation_method="udev"
+    elif test "x$with_systemd" = "xyes"; then
+      activation_method="systemd"
+      echo "*** Note: support for udev activation has been disabled, using systemd activation instead ***"
     else
-      AC_DEFINE(HAVE_SYSTEMD, 1, [Define to enable systemd support])
-      SYSTEMD_SUB=systemd
+      activation_method="manual"
+      echo "*** Note: support for udev/systemd activation have been disabled, using manual activation instead ***"
     fi
     ;;
 esac
 AM_CONDITIONAL(WIN32, test x$win32 = xtrue)
 
-AC_SUBST([UDEV_SUB])
-AC_SUBST([SYSTEMD_SUB])
-
 AS_COMPILER_FLAGS(GLOBAL_CFLAGS, "-Wall -Wextra -Wmissing-declarations -Wredundant-decls -Wshadow -Wpointer-arith  -Wwrite-strings -Wswitch-default -Wno-unused-parameter")
 AC_SUBST(GLOBAL_CFLAGS)
 
@@ -180,11 +198,11 @@ Configuration for $PACKAGE $VERSION:
   preflight worker support ..: $have_limd
   activation method .........: $activation_method"
 
-if test "x$activation_method" = "xsystemd"; then
+if test "x$with_systemd" = "xyes"; then
   echo "  systemd unit directory ....: ${systemdsystemunitdir}"
 fi
 
-if test -n "$udevrulesdir"; then
+if test "x$with_udev" = "xyes"; then
   echo "  udev rules directory ......: ${udevrulesdir}"
 fi
 

udev/Makefile.am

@@ -4,6 +4,8 @@ edit = \
 	-e 's|@sbindir[@]|$(sbindir)|g' \
 	< $< > $@ || rm $@
 
+if WANT_UDEV
+
 udevrules_DATA = \
 	39-usbmuxd.rules
 
@@ -18,3 +20,5 @@ MAINTAINERCLEANFILES = \
 
 CLEANFILES = \
 	39-usbmuxd.rules
+
+endif