[PATCH 1/2] Add helper to load linux kmods

[Ismael Luceno]

The function checks for already loaded (incl. built-in) modules first at
/sys/module/, then tries to load it.

Abort when unable to load efivarfs/efivars.

Signed-off-by: Ismael Luceno <iluceno@suse.de>
---
 grub-core/osdep/unix/platform.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/grub-core/osdep/unix/platform.c b/grub-core/osdep/unix/platform.c
index de712211cf09..a5bf064b7cf5 100644
--- a/grub-core/osdep/unix/platform.c
+++ b/grub-core/osdep/unix/platform.c
@@ -26,8 +26,25 @@
 #include <grub/emu/exec.h>
 #include <sys/types.h>
 #include <dirent.h>
+#include <stdio.h>
 #include <string.h>
 #include <errno.h>
+#include <unistd.h>
+
+static int
+linux_kmod_load (const char *name)
+{
+#ifdef __linux__
+  char path[64];
+  if (snprintf (path, sizeof(path), "/sys/module/%s", name) >= sizeof(path))
+    grub_util_error (_("module name `%s' too long"), name);
+  if (!access (path, F_OK))
+    return 0;
+  return grub_util_exec ((const char * []){ "modprobe", "-q", name, NULL });
+#else
+  return 0;
+#endif
+}
 
 static char *
 get_ofpathname (const char *dev)
@@ -149,10 +166,9 @@ grub_install_register_efi (grub_device_t efidir_grub_dev,
       grub_util_error (_("%s: not found"), "efibootmgr");
     }
 
-  /* On Linux, we need the efivars kernel modules.  */
-#ifdef __linux__
-  grub_util_exec ((const char * []){ "modprobe", "-q", "efivars", NULL });
-#endif
+  /* On Linux, we need efivarfs (or the legacy efivars).  */
+  linux_kmod_load ("efivars");
+
   /* Delete old entries from the same distributor.  */
   ret = grub_install_remove_efi_entries_by_distributor (efi_distributor);
   if (ret)
-- 
2.37.1