configure.ac: clean up libmilter detection

This behaviour should be compatible with AX_CHECK_LIBRARY if we want
to move to that in the future, but since we're only doing it for one
library it felt easier to just write it out.

CHANGELOG.md

@@ -17,6 +17,9 @@ All notable changes to this project will be documented in this file.
 - Custom Jansson locations must be configured using `LIBJANSSON_CFLAGS`
   and `LIBJANSSON_LIBS` environment variables instead of passing
   `--with-libjansson=/path` to `configure`.
+- Custom libmilter locations must be configured using `LIBMILTER_CPPFLAGS`
+  and `LIBMILTER_LDFLAGS` environment variables instead of passing
+  `--with-milter=/path` to `configure`.
 - Building the milter defaults to requiring Jansson. You can explicitly
   disable it by passing `--without-libjansson` to `configure`.
 - Libidn2 is now required to build OpenARC.

Makefile.am

@@ -88,8 +88,8 @@ openarc_openarc_SOURCES = \
 	util/arc-dstring.h
 openarc_openarc_CC = $(PTHREAD_CC)
 openarc_openarc_CFLAGS = $(PTHREAD_CFLAGS)
-openarc_openarc_CPPFLAGS = -I$(srcdir)/libopenarc -I$(srcdir)/util $(OPENSSL_CFLAGS) $(LIBIDN2_CFLAGS) $(LIBMILTER_INCDIRS) $(LIBJANSSON_CFLAGS)
-openarc_openarc_LDFLAGS = $(LIBMILTER_LIBDIRS) $(PTHREAD_CFLAGS)
+openarc_openarc_CPPFLAGS = -I$(srcdir)/libopenarc -I$(srcdir)/util $(OPENSSL_CFLAGS) $(LIBIDN2_CFLAGS) $(LIBMILTER_CPPFLAGS) $(LIBJANSSON_CFLAGS)
+openarc_openarc_LDFLAGS = $(LIBMILTER_LDFLAGS) $(PTHREAD_CFLAGS)
 openarc_openarc_LDADD = libopenarc/libopenarc.la $(LIBMILTER_LIBS) $(OPENSSL_LIBS) $(LIBIDN2_LIBS) $(PTHREAD_LIBS) $(LIBJANSSON_LIBS) $(LIBRESOLV)
 endif
 

README.md

@@ -91,6 +91,9 @@ $ make
 $ make install
 ```
 
+You can get a list of available flags and environment variables to
+influence the build by running `./configure --help`.
+
 ## Testing
 
 Tests can be run with `make check`. OpenARC's test suite requires:

configure.ac

@@ -327,123 +327,46 @@ AC_SUBST(LIBIDN2_LIBS)
 #
 # libmilter
 #
-AC_MSG_CHECKING([for milter library and includes])
-AC_ARG_WITH([milter],
-            AS_HELP_STRING([--with-milter],
-                           [location of milter includes and library]),
-            [milterpath="$withval"], [milterpath="auto"])
 
-if test x"$enable_filter" = x"no"
-then
-	milterpath="no"
-fi
+AC_ARG_VAR([LIBMILTER_CPPFLAGS], [C preprocessor flags for libmilter headers])
+AC_ARG_VAR([LIBMILTER_LDFLAGS], [linker flags for libmilter library])
 
-if test "$milterpath" = "auto" -o "$milterpath" = "yes"
-then
-	milterdirs="/usr/local /opt/local /usr"
-	for d in $milterdirs
-	do
-		if test -f $d/include/libmilter/mfapi.h
-		then
-			milterpath=$d
-			break
-		fi
-	done
-fi
-case "$milterpath" in
-	no)
-		if test x"$enable_filter" = x"yes"
-		then
-			AC_MSG_ERROR([milter is required])
-		fi
-		AC_MSG_RESULT(disabled)
-		;;
-	auto)
-		AC_MSG_ERROR([milter not found])
-		;;
-	*/*)
-		if ! test -f $milterpath/include/libmilter/mfapi.h
-		then
-			AC_MSG_ERROR([milter includes not found at $milterpath])
-		fi
-		AC_MSG_RESULT([$milterpath])
-		;;
-	*)
-		AC_MSG_ERROR([milter not found])
-		;;
-esac
-
-LIBMILTER_INCDIRS=""
-LIBMILTER_LIBDIRS=""
-LIBMILTER_LIBS=""
-
-if test x"$milterpath" != x"no"
-then
-	LIBMILTER_INCDIRS="-I$milterpath/include"
+AS_IF([test "x$enable_filter" != xno], [
+    saved_CPPFLAGS="$CPPFLAGS"
+    saved_LDFLAGS="$LDFLAGS"
+    saved_LIBS="$LIBS"
 
-	saved_CC="$CC"
-	saved_CFLAGS="$CFLAGS"
-	saved_CPPFLAGS="$CPPFLAGS"
-	saved_LDFLAGS="$LDFLAGS"
-	saved_LIBS="$LIBS"
+    AS_IF([test "x$LIBMILTER_CPPFLAGS" != x], [CPPFLAGS="$CPPFLAGS $LIBMILTER_CPPFLAGS"])
+    AS_IF([test "x$LIBMILTER_LDFLAGS" != x], [LDFLAGS="$LDFLAGS $LIBMILTER_LDFLAGS"])
 
-	CC="$PTHREAD_CC"
-	LIBS="$outer_LIBS $PTHREAD_LIBS $saved_LIBS"
-	CPPFLAGS="$LIBMILTER_INCDIRS $saved_CPPFLAGS"
-	CFLAGS="$PTHREAD_CFLAGS $saved_CFLAGS"
-	LDFLAGS="$outer_LDFLAGS $PTHREAD_CFLAGS $saved_LDFLAGS"
+    AC_CHECK_HEADER([libmilter/mfapi.h],
+        [AC_CHECK_LIB([milter], [smfi_register], [], [AC_MSG_ERROR([Unable to find libmilter])])],
+        [AC_MSG_ERROR([Unable to find libmilter includes])])
 
-	breakloop="no"
-	for d in lib lib64 lib/libmilter
-	do
-		unset ac_cv_search_smfi_register
-		LDFLAGS="$outer_LDFLAGS $PTHREAD_CFLAGS -L$milterpath/$d $saved_LDFLAGS"
-		AC_SEARCH_LIBS([smfi_register], [milter],
-		               [
-		               	LIBMILTER_LIBDIRS="-L$milterpath/$d"
-		               	LIBMILTER_LIBS="-lmilter"
-		               	breakloop="yes"
-		               ])
-
-		AC_CHECK_FUNC([smfi_insheader],
-			      AC_DEFINE([HAVE_SMFI_INSHEADER], 1,
-					[Define if libmilter has smfi_insheader()]))
-
-		AC_CHECK_FUNC([smfi_opensocket],
-			      AC_DEFINE([HAVE_SMFI_OPENSOCKET], 1,
-					[Define if libmilter has smfi_opensocket()]))
-
-		AC_CHECK_FUNC([smfi_progress],
-			      AC_DEFINE([HAVE_SMFI_PROGRESS], 1,
-					[Define if libmilter has smfi_progress()]))
-
-		AC_CHECK_FUNC([smfi_setsymlist],
-			      AC_DEFINE([HAVE_SMFI_SETSYMLIST], 1,
-					[Define if libmilter has smfi_setsymlist()]))
-
-		AC_CHECK_FUNC([smfi_version],
-			      AC_DEFINE([HAVE_SMFI_VERSION], 1,
-					[Define if libmilter has smfi_version()]))
-
-		if test x"$breakloop" = x"yes"
-		then
-			break
-		fi
-	done
-	if test x"$LIBMILTER_LIBDIRS" = x""
-	then
-		AC_MSG_ERROR([libmilter not found])
-	fi
-
-	CC="$saved_CC"
-	CPPFLAGS="$saved_CPPFLAGS"
-	CFLAGS="$saved_CFLAGS"
-	LDFLAGS="$saved_LDFLAGS"
-	LIBS="$saved_LIBS"
-fi
+    AC_CHECK_FUNC([smfi_insheader],
+        AC_DEFINE([HAVE_SMFI_INSHEADER], 1, [Define if libmilter has smfi_insheader()]))
+
+    AC_CHECK_FUNC([smfi_opensocket],
+        AC_DEFINE([HAVE_SMFI_OPENSOCKET], 1, [Define if libmilter has smfi_opensocket()]))
+
+    AC_CHECK_FUNC([smfi_progress],
+        AC_DEFINE([HAVE_SMFI_PROGRESS], 1, [Define if libmilter has smfi_progress()]))
+
+    AC_CHECK_FUNC([smfi_setsymlist],
+        AC_DEFINE([HAVE_SMFI_SETSYMLIST], 1, [Define if libmilter has smfi_setsymlist()]))
+
+    AC_CHECK_FUNC([smfi_version],
+        AC_DEFINE([HAVE_SMFI_VERSION], 1, [Define if libmilter has smfi_version()]))
+
+    CPPFLAGS="$saved_CPPFLAGS"
+    LDFLAGS="$saved_LDFLAGS"
+    LIBS="$saved_LIBS"
+
+    LIBMILTER_LIBS='-lmilter'
+])
 
-AC_SUBST(LIBMILTER_INCDIRS)
-AC_SUBST(LIBMILTER_LIBDIRS)
+AC_SUBST(LIBMILTER_CPPFLAGS)
+AC_SUBST(LIBMILTER_LDFLAGS)
 AC_SUBST(LIBMILTER_LIBS)
 
 #