As someone who wrote a similar patch several years ago for a personal
project and submitted it to the list, what's the advantage of this patch
over the previous ones that have been submitted (other than, I believe, the
ability to set the GUID)?
On Mon, Jan 23, 2017 at 7:25 PM Matthew Garrett <mj...@coreos.com> wrote:
> 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
>
>
>
> +@node getenv
>
> +@subsection getenv
>
> +
>
> +@deffn Command getenv [@option{-e}] [@option{-g}] 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
>
>
>
>
>
> _______________________________________________
>
> Grub-devel mailing list
>
> Grub-devel@gnu.org
>
> https://lists.gnu.org/mailman/listinfo/grub-devel
>
>
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