grub2/0003-cmdline-add-envvar-loader_cmdline_append.patch

From: Michael Chang <mchang@suse.com>
Subject: add loader_cmdline_append environment variable

Add loader_cmdline_append environment variable that appends it's
value to the loader's command line. We can use this variable to
assign values determined at run time. It will take effect on any
subsidiary configs loaded using configfile as well.

By means of this variable, we can, for example, set rootflags=
according to the selected btrfs snapshots and tell linux kernel's
btrfs module to mount the snapshot by the subvolume name or id.

Signed-off-by: Michael Chang <mchang@suse.com>
---
 grub-core/lib/cmdline.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/grub-core/lib/cmdline.c b/grub-core/lib/cmdline.c
index a702e64..c5be945 100644
--- a/grub-core/lib/cmdline.c
+++ b/grub-core/lib/cmdline.c
@@ -19,6 +19,8 @@
 
 #include <grub/lib/cmdline.h>
 #include <grub/misc.h>
+#include <grub/mm.h>
+#include <grub/env.h>
 
 static unsigned int check_arg (char *c, int *has_space)
 {
@@ -65,6 +67,8 @@ int grub_create_loader_cmdline (int argc, char *argv[], char *buf,
   int i, space;
   unsigned int arg_size;
   char *c;
+  const char *append = NULL;
+  grub_size_t append_size = 0;
 
   for (i = 0; i < argc; i++)
     {
@@ -95,6 +99,23 @@ int grub_create_loader_cmdline (int argc, char *argv[], char *buf,
       *buf++ = ' ';
     }
 
+  append = grub_env_get ("loader_cmdline_append");
+
+  if (append)
+    append_size = grub_strlen (append);
+
+  if (append_size)
+    {
+      append_size++;
+      if (size >= append_size)
+        {
+          grub_strcpy (buf, append);
+          buf += append_size;
+          size -= append_size;
+          i++;
+        }
+    }
+
   /* Replace last space with null.  */
   if (i)
     buf--;
-- 
1.8.1.4