build: Find grub2-mkconfig a bit more automagically

If one happens to not have grub2 installed, the previous commit
would cause us to fall back to `grub-mkconfig` with bad results.

We should likely just do dynamic detection and avoid pain, but
there's no harm in also allowing this to be statically determined.

The automagic here is that if `/etc/os-release` says `ID_LIKE=fedora`,
we know to use `grub2-mkconfig`.  But distro scripts should set this
in the build configurations using `--with-grub2-mkconfig=`.

Closes: #240
Approved by: jlebon

diff --git a/configure.ac b/configure.ac
index 7dfcd50096089efd05c0b0ad39cfab54f0d8e4b3..24dfb3565f44d55b4dd1b5cac4035f4e52ea75bf 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -257,14 +257,17 @@ AC_ARG_WITH(builtin-grub2-mkconfig,
               [with_builtin_grub2_mkconfig=no])
 AM_CONDITIONAL(BUILDOPT_BUILTIN_GRUB2_MKCONFIG, test x$with_builtin_grub2_mkconfig = xyes)
 AM_COND_IF(BUILDOPT_BUILTIN_GRUB2_MKCONFIG,
-           AC_DEFINE([USE_BUILTIN_GRUB2_MKCONFIG], 1, [Define if using internal ostree-grub-generator]),
-[
-  # Otherwise, look for the path to the system generator.  On some
-  # distributions GRUB2 *-mkconfig executable has 'grub2' prefix and
-  # on some 'grub'.
-  AC_CHECK_PROG(GRUB2_MKCONFIG, grub2-mkconfig, grub2-mkconfig, grub-mkconfig)
-  AC_DEFINE_UNQUOTED([GRUB2_MKCONFIG_PATH], ["$GRUB2_MKCONFIG"], [The system grub2-mkconfig executible name])
-])
+           AC_DEFINE([USE_BUILTIN_GRUB2_MKCONFIG], 1, [Define if using internal ostree-grub-generator]))
+AC_ARG_WITH(grub2-mkconfig-path,
+            AS_HELP_STRING([--with-grub2-mkconfig-path],
+                           [Path to grub2-mkconfig]))
+AS_IF([test x$with_grub2_mkconfig_path = x], [
+  dnl Otherwise, look for the path to the system generator.  On some
+  dnl distributions GRUB2 *-mkconfig executable has 'grub2' prefix and
+  dnl on some 'grub'.  We default to grub2-mkconfig.
+  AC_CHECK_PROGS(GRUB2_MKCONFIG, [grub2-mkconfig grub-mkconfig], [grub2-mkconfig])
+],[GRUB2_MKCONFIG=$with_grub2_mkconfig_path])
+AC_DEFINE_UNQUOTED([GRUB2_MKCONFIG_PATH], ["$GRUB2_MKCONFIG"], [The system grub2-mkconfig executible name])
 
 dnl for tests
 AS_IF([test "x$found_introspection" = xyes], [
@@ -301,8 +304,12 @@ echo "
     api docs (gtk-doc):                           $enable_gtk_doc
     gjs-based tests:                              $have_gjs
     dracut:                                       $with_dracut
-    mkinitcpio:                                   $with_mkinitcpio
-    builtin grub2-mkconfig (instead of system):   $with_builtin_grub2_mkconfig"
+    mkinitcpio:                                   $with_mkinitcpio"
+AS_IF([test x$with_builtin_grub2_mkconfig = xyes], [
+    echo "    builtin grub2-mkconfig (instead of system):   $with_builtin_grub2_mkconfig"
+], [
+    echo "    grub2-mkconfig path:                          $GRUB2_MKCONFIG"
+])
 AS_IF([test "x$with_systemd" = "xyes"], [
     echo "    systemd unit dir:                             $with_systemdsystemunitdir"
 ])