Added support for remote booting: commands "expires" and "fallback"

stage2/builtins.c

@@ -1138,6 +1138,64 @@ static struct builtin builtin_embed =
   " Print the number of sectors which STAGE1_5 occupies if successful."
 };
 
+
+/* expires */
+
+static unsigned char parsebcdbyte (char *str)
+{
+  if ((str [0] >= '0') && (str [0] <= '9') && (str [1] >= '0') && (str [1] <= '9'))
+    {
+      return ( str [0] << 4 ) + str [1] - ( 17 * '0' );
+    }
+  return 0xff;
+};
+
+unsigned char rtc_now [6];
+unsigned char expires [6];
+
+static int
+expires_func (char *arg, int flags)
+{
+		/* Store YYYYMMDDHHMM in expires[] */
+  if (	((expires [0] = parsebcdbyte (arg+ 0)) == 0xff) ||
+	((expires [1] = parsebcdbyte (arg+ 2)) == 0xff) ||
+	(arg [ 4] != '-') ||
+	((expires [2] = parsebcdbyte (arg+ 5)) == 0xff) ||
+	(arg [ 7] != '-') ||
+	((expires [3] = parsebcdbyte (arg+ 8)) == 0xff) ||
+	(arg [10] != ' ') ||
+	((expires [4] = parsebcdbyte (arg+11)) == 0xff) ||
+	(arg [13] != ':') ||
+	((expires [5] = parsebcdbyte (arg+14)) == 0xff) ||
+	(arg [16] != 0) )
+    {
+      errnum = ERR_DATESTAMP;
+      return 1;
+    }
+
+  get_rtc_now ();	/* Call BIOS to fill rtc_now[6] with YYYYMMDDHHMM */
+
+  if (grub_memcmp (rtc_now, expires, 6) >= 0)
+    {
+      errnum = ERR_EXPIRED;
+      return 1;	/* Failure: this boot entry has expired, try fallback */
+    }
+
+  return 0;	/* Success: this boot entry has not expired yet */
+};
+
+static struct builtin builtin_expires =
+{
+  "expires",
+  expires_func,
+  BUILTIN_MENU | BUILTIN_CMDLINE | BUILTIN_HELP_LIST,
+  "expires YYYY-MM-DD HH:MM",
+  "The current boot entry fails after the realtime clock reaches"
+  " the date and time provided.  This may be useful to test new kernels"
+  " on distant systems -- rebooting those after a testing period can"
+  " fallback to the old kernel when the boot entry under test expires."
+};
+
 
 /* fallback */
 static int
@@ -1153,15 +1211,13 @@ static struct builtin builtin_fallback =
 {
   "fallback",
   fallback_func,
-  BUILTIN_MENU,
-#if 0
+  BUILTIN_MENU | BUILTIN_CMDLINE | BUILTIN_HELP_LIST,
   "fallback NUM",
   "Go into unattended boot mode: if the default boot entry has any"
   " errors, instead of waiting for the user to do anything, it"
   " immediately starts over using the NUM entry (same numbering as the"
   " `default' command). This obviously won't help if the machine"
-  " was rebooted by a kernel that GRUB loaded."
-#endif
+  " was rebooted by a kernel that GRUB loaded, unless combined with expires."
 };
 
 
@@ -4690,6 +4746,7 @@ struct builtin *builtin_table[] =
   &builtin_dump,
 #endif /* GRUB_UTIL */
   &builtin_embed,
+  &builtin_expires,
   &builtin_fallback,
   &builtin_find,
   &builtin_fstest,