/*
* Copyright (C) 2023 Michael Brown <mbrown@fensystems.co.uk>.
*
* This program 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 2 of the
* License, or any later version.
*
* This program 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 this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*
* You can also choose to distribute this program under the terms of
* the Unmodified Binary Distribution Licence (as given in the file
* COPYING.UBDL), provided that you have satisfied its requirements.
*/
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
/**
* @file
*
* EFI variable settings
*
*/
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <ipxe/settings.h>
#include <ipxe/init.h>
#include <ipxe/efi/efi.h>
#include <ipxe/efi/efi_strings.h>
/** EFI variable settings scope */
static const struct settings_scope efivars_scope;
/** EFI variable settings */
static struct settings efivars;
/**
* Check applicability of EFI variable setting
*
* @v settings Settings block
* @v setting Setting
* @ret applies Setting applies within this settings block
*/
static int efivars_applies ( struct settings *settings __unused,
const struct setting *setting ) {
return ( setting->scope == &efivars_scope );
}
/**
* Find first matching EFI variable name
*
* @v wname Name
* @v guid GUID to fill in
* @ret rc Return status code
*/
static int efivars_find ( const CHAR16 *wname, EFI_GUID *guid ) {
EFI_RUNTIME_SERVICES *rs = efi_systab->RuntimeServices;
size_t wname_len = ( ( wcslen ( wname ) + 1 ) * sizeof ( wname[0] ) );
CHAR16 *buf;
CHAR16 *tmp;
UINTN size;
EFI_STATUS efirc;
int rc;
/* Allocate single wNUL for first call to GetNextVariableName() */
size = sizeof ( buf[0] );
buf = zalloc ( size );
if ( ! buf )
return -ENOMEM;
/* Iterate over all veriables */
while ( 1 ) {
/* Get next variable name */
efirc = rs->GetNextVariableName ( &size, buf, guid );
if ( efirc == EFI_BUFFER_TOO_SMALL ) {
tmp = realloc ( buf, size );
if ( ! tmp ) {
rc = -ENOMEM;
break;
}
buf = tmp;
efirc = rs->GetNextVariableName ( &size, buf, guid );
}
if ( efirc == EFI_NOT_FOUND ) {
rc = -ENOENT;
break;
}
if ( efirc != 0 ) {
rc = -EEFI ( efirc );
DBGC ( &efivars, "EFIVARS %s:%ls could not fetch next "
"variable name: %s\n",
efi_guid_ntoa ( guid ), buf, strerror ( rc ) );
break;
}
DBGC2 ( &efivars, "EFIVARS %s:%ls exists\n",
efi_guid_ntoa ( guid ), buf );
/* Check for matching variable name */
if ( memcmp ( wname, buf, wname_len ) == 0 ) {
rc = 0;
break;
}
}
/* Free temporary buffer */
free ( buf );
return rc;
}
/**
* Fetch value of EFI variable setting
*
* @v settings Settings block
* @v setting Setting to fetch
* @v data Buffer to fill with setting data
* @v len Length of buffer
* @ret len Length of setting data, or negative error
*/
static int efivars_fetch ( struct settings *settings __unused,
struct setting *setting, void *data, size_t len ) {
EFI_RUNTIME_SERVICES *rs = efi_systab->RuntimeServices;
size_t name_len = strlen ( setting->name );
CHAR16 wname[ name_len + 1 /* wNUL */ ];
EFI_GUID guid;
UINT32 attrs;
UINTN size;
void *buf;
EFI_STATUS efirc;
int rc;
/* Convert name to UCS-2 */
efi_snprintf ( wname, sizeof ( wname ), "%s", setting->name );
/* Find variable GUID */
if ( ( rc = efivars_find ( wname, &guid ) ) != 0 )
goto err_find;
/* Get variable length */
size = 0;
if ( ( efirc = rs->GetVariable ( wname, &guid, &attrs, &size,
NULL ) != EFI_BUFFER_TOO_SMALL ) ) {
rc = -EEFI ( efirc );
DBGC ( &efivars, "EFIVARS %s:%ls could not get size: %s\n",
efi_guid_ntoa ( &guid ), wname, strerror ( rc ) );
goto err_len;
}
/* Allocate temporary buffer, since GetVariable() is not
* guaranteed to return partial data for an underlength
* buffer.
*/
buf = malloc ( size );
if ( ! buf ) {
rc = -ENOMEM;
goto err_alloc;
}
/* Get variable value */
if ( ( efirc = rs->GetVariable ( wname, &guid, &attrs, &size,
buf ) ) != 0 ) {
rc = -EEFI ( efirc );
DBGC ( &efivars, "EFIVARS %s:%ls could not get %zd bytes: "
"%s\n", efi_guid_ntoa ( &guid ), wname,
( ( size_t ) size ), strerror ( rc ) );
goto err_get;
}
DBGC ( &efivars, "EFIVARS %s:%ls:\n", efi_guid_ntoa ( &guid ), wname );
DBGC_HDA ( &efivars, 0, buf, size );
/* Return setting value */
if ( len > size )
len = size;
memcpy ( data, buf, len );
if ( ! setting->type )
setting->type = &setting_type_hex;
/* Free temporary buffer */
free ( buf );
return size;
err_get:
free ( buf );
err_alloc:
err_len:
err_find:
return rc;
}
/** EFI variable settings operations */
static struct settings_operations efivars_operations = {
.applies = efivars_applies,
.fetch = efivars_fetch,
};
/** EFI variable settings */
static struct settings efivars = {
.refcnt = NULL,
.siblings = LIST_HEAD_INIT ( efivars.siblings ),
.children = LIST_HEAD_INIT ( efivars.children ),
.op = &efivars_operations,
.default_scope = &efivars_scope,
};
/**
* Initialise EFI variable settings
*
*/
static void efivars_init ( void ) {
int rc;
/* Register settings block */
if ( ( rc = register_settings ( &efivars, NULL, "efi" ) ) != 0 ) {
DBGC ( &efivars, "EFIVARS could not register: %s\n",
strerror ( rc ) );
return;
}
}
/** EFI variable settings initialiser */
struct init_fn efivars_init_fn __init_fn ( INIT_NORMAL ) = {
.initialise = efivars_init,
};
