grub/grub-core/commands/efi/getenv.c
Matthew Garrett 2755ecd157 Add efi getenv command
Add a command to obtain the contents of EFI firmware variables.
2015-04-22 13:08:26 -07:00

153 lines
4.1 KiB
C

/* 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);
}