[PATCH] Add efi getenv command

[Matthew Garrett]

Add a command to obtain the contents of EFI firmware variables.
---
 docs/grub.texi                  |   7 ++
 grub-core/Makefile.core.def     |   7 ++
 grub-core/commands/efi/getenv.c | 153 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 167 insertions(+)
 create mode 100644 grub-core/commands/efi/getenv.c

diff --git a/docs/grub.texi b/docs/grub.texi
index b9ddb9b..4469638 100644
--- a/docs/grub.texi
+++ b/docs/grub.texi
@@ -3818,6 +3818,7 @@ you forget a command, you can run the command 
@command{help}
 * eval::                        Evaluate agruments as GRUB commands
 * export::                      Export an environment variable
 * false::                       Do nothing, unsuccessfully
+* getenv::                      Retrieve an EFI firmware variable
 * gettext::                     Translate a string
 * gptsync::                     Fill an MBR based on GPT entries
 * halt::                        Shut down your computer
@@ -4258,6 +4259,12 @@ Do nothing, unsuccessfully.  This is mainly useful in 
control constructs
 such as @code{if} and @code{while} (@pxref{Shell-like scripting}).
 @end deffn
 
address@hidden getenv
address@hidden getenv
+
address@hidden Command getenv address@hidden address@hidden envvar
+Retrieves an EFI variable with the name provided by @option{-e} and the GUID
+provied by @option{-g} and stores it in environment variable @var{envvar}
 
 @node gettext
 @subsection gettext
diff --git a/grub-core/Makefile.core.def b/grub-core/Makefile.core.def
index 2dfa22a..db77a7f 100644
--- a/grub-core/Makefile.core.def
+++ b/grub-core/Makefile.core.def
@@ -817,6 +817,13 @@ module = {
 };
 
 module = {
+  name = getenv;
+  common = commands/efi/getenv.c;
+  enable = i386_efi;
+  enable = x86_64_efi;
+};
+
+module = {
   name = gptsync;
   common = commands/gptsync.c;
 };
diff --git a/grub-core/commands/efi/getenv.c b/grub-core/commands/efi/getenv.c
new file mode 100644
index 0000000..5a829f5
--- /dev/null
+++ b/grub-core/commands/efi/getenv.c
@@ -0,0 +1,153 @@
+/* getenv.c - retrieve EFI variables.  */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2009  Free Software Foundation, Inc.
+ *  Copyright (C) 2014  CoreOS, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/efi/efi.h>
+#include <grub/dl.h>
+#include <grub/env.h>
+#include <grub/err.h>
+#include <grub/extcmd.h>
+#include <grub/i18n.h>
+#include <grub/misc.h>
+#include <grub/mm.h>
+
+GRUB_MOD_LICENSE ("GPLv3+");
+
+static const struct grub_arg_option options_getenv[] = {
+  {"var-name", 'e', 0,
+   N_("Environment variable to query"),
+   N_("VARNAME"), ARG_TYPE_STRING},
+  {"var-guid", 'g', 0,
+   N_("GUID of environment variable to query"),
+   N_("GUID"), ARG_TYPE_STRING},
+  {"binary", 'b', 0,
+   N_("Read binary data and represent it as hex"),
+   0, ARG_TYPE_NONE},
+  {0, 0, 0, 0, 0, 0}
+};
+
+enum options_getenv
+{
+  GETENV_VAR_NAME,
+  GETENV_VAR_GUID,
+  GETENV_BINARY,
+};
+
+static grub_err_t
+grub_cmd_getenv (grub_extcmd_context_t ctxt, int argc, char **args)
+{
+  struct grub_arg_list *state = ctxt->state;
+  char *envvar = NULL, *guid = NULL, *bindata = NULL, *data = NULL;
+  grub_size_t datasize;
+  grub_efi_guid_t efi_var_guid;
+  grub_efi_boolean_t binary = state[GETENV_BINARY].set;
+  unsigned int i;
+
+  if (!state[GETENV_VAR_NAME].set || !state[GETENV_VAR_GUID].set)
+    {
+      grub_error (GRUB_ERR_INVALID_COMMAND, N_("-e and -g are required"));
+      goto done;
+    }
+
+  if (argc != 1)
+    {
+      grub_error (GRUB_ERR_BAD_ARGUMENT, N_("unexpected arguments"));
+      goto done;
+    }
+
+  envvar = state[GETENV_VAR_NAME].arg;
+  guid = state[GETENV_VAR_GUID].arg;
+
+  if (grub_strlen(guid) != 36 ||
+      guid[8] != '-' ||
+      guid[13] != '-' ||
+      guid[18] != '-' ||
+      guid[23] != '-')
+    {
+      grub_error (GRUB_ERR_BAD_ARGUMENT, N_("invalid GUID"));
+      goto done;
+    }
+
+  /* Forgive me father for I have sinned */
+  guid[8] = 0;
+  efi_var_guid.data1 = grub_strtoul(guid, NULL, 16);
+  guid[13] = 0;
+  efi_var_guid.data2 = grub_strtoul(guid + 9, NULL, 16);
+  guid[18] = 0;
+  efi_var_guid.data3 = grub_strtoul(guid + 14, NULL, 16);
+  efi_var_guid.data4[7] = grub_strtoul(guid + 34, NULL, 16);
+  guid[34] = 0;
+  efi_var_guid.data4[6] = grub_strtoul(guid + 32, NULL, 16);
+  guid[32] = 0;
+  efi_var_guid.data4[5] = grub_strtoul(guid + 30, NULL, 16);
+  guid[30] = 0;
+  efi_var_guid.data4[4] = grub_strtoul(guid + 28, NULL, 16);
+  guid[28] = 0;
+  efi_var_guid.data4[3] = grub_strtoul(guid + 26, NULL, 16);
+  guid[26] = 0;
+  efi_var_guid.data4[2] = grub_strtoul(guid + 24, NULL, 16);
+  guid[23] = 0;
+  efi_var_guid.data4[1] = grub_strtoul(guid + 21, NULL, 16);
+  guid[21] = 0;
+  efi_var_guid.data4[0] = grub_strtoul(guid + 19, NULL, 16);
+
+  data = grub_efi_get_variable(envvar, &efi_var_guid, &datasize);
+
+  if (!data || !datasize)
+    {
+      grub_error (GRUB_ERR_FILE_NOT_FOUND, N_("No such variable"));
+      goto done;
+    }
+
+  if (binary)
+    {
+      bindata = grub_zalloc(datasize * 2 + 1);
+      for (i=0; i<datasize; i++)
+         grub_snprintf(bindata + i*2, 3, "%02x", data[i]);
+
+      if (grub_env_set (args[0], bindata))
+       goto done;
+    }
+  else if (grub_env_set (args[0], data))
+    {
+      goto done;
+    }
+
+  grub_errno = GRUB_ERR_NONE;
+
+done:
+  grub_free(bindata);
+  grub_free(data);
+  return grub_errno;
+}
+
+static grub_extcmd_t cmd_getenv;
+
+GRUB_MOD_INIT(getenv)
+{
+  cmd_getenv = grub_register_extcmd ("getenv", grub_cmd_getenv, 0,
+                                  N_("-e envvar -g guidenv setvar"),
+                                  N_("Read a firmware environment variable"),
+                                  options_getenv);
+}
+
+GRUB_MOD_FINI(getenv)
+{
+  grub_unregister_extcmd (cmd_getenv);
+}
-- 
2.9.3