[ostree: 40/70] build: Find grub2-mkconfig a bit more automagically

[Colin Walters <walters src gnome org>]

commit e9640ca4d91fffa899f7a7ba14bae798215fb6a6
Author: Colin Walters <walters verbum org>
Date:   Wed Apr 6 14:22:19 2016 -0400

    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

 configure.ac |   27 +++++++++++++++++----------
 1 files changed, 17 insertions(+), 10 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 7dfcd50..24dfb35 100644
--- 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"
 ])