Add ability to read serial number from SMBIOS
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Michael Brown
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3fd10074d8
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22ed1fbaf1
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/*
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* Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <stdint.h>
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#include <string.h>
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#include <stdio.h>
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#include <errno.h>
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#include <realmode.h>
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#include <pnpbios.h>
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#include <smbios.h>
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/** @file
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*
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* System Management BIOS
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*
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*/
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/** Signature for an SMBIOS structure */
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#define SMBIOS_SIGNATURE \
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( ( '_' << 0 ) + ( 'S' << 8 ) + ( 'M' << 16 ) + ( '_' << 24 ) )
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/** SMBIOS entry point */
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struct smbios_entry {
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/** Signature
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*
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* Must be equal to SMBIOS_SIGNATURE
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*/
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uint32_t signature;
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/** Checksum */
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uint8_t checksum;
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/** Length */
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uint8_t length;
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/** Major version */
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uint8_t major;
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/** Minor version */
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uint8_t minor;
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/** Maximum structure size */
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uint16_t max;
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/** Entry point revision */
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uint8_t revision;
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/** Formatted area */
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uint8_t formatted[5];
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/** DMI Signature */
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uint8_t dmi_signature[5];
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/** DMI checksum */
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uint8_t dmi_checksum;
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/** Structure table length */
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uint16_t smbios_length;
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/** Structure table address */
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physaddr_t smbios_address;
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/** Number of SMBIOS structures */
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uint16_t smbios_count;
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/** BCD revision */
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uint8_t bcd_revision;
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} __attribute__ (( packed ));
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/** An SMBIOS structure */
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struct smbios {
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/** Type */
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uint8_t type;
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/** Length */
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uint8_t length;
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/** Handle */
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uint16_t handle;
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} __attribute__ (( packed ));
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struct smbios_system_information {
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struct smbios header;
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uint8_t manufacturer;
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uint8_t product;
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uint8_t version;
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uint8_t serial;
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} __attribute__ (( packed ));
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/**
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* Find SMBIOS
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*
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* @v emtry SMBIOS entry point to fill in
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* @ret rc Return status code
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*/
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static int find_smbios_entry ( struct smbios_entry *entry ) {
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union {
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struct smbios_entry entry;
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uint8_t bytes[256]; /* 256 is maximum length possible */
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} u;
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unsigned int offset;
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size_t len;
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unsigned int i;
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uint8_t sum = 0;
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/* Try to find SMBIOS */
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for ( offset = 0 ; offset < 0x10000 ; offset += 0x10 ) {
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/* Read start of header and verify signature */
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copy_from_real ( &u.entry, BIOS_SEG, offset,
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sizeof ( u.entry ));
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if ( u.entry.signature != SMBIOS_SIGNATURE )
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continue;
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/* Read whole header and verify checksum */
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len = u.entry.length;
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copy_from_real ( &u.bytes, BIOS_SEG, offset, len );
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for ( i = 0 ; i < len ; i++ ) {
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sum += u.bytes[i];
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}
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if ( sum != 0 ) {
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DBG ( "SMBIOS at %04x:%04x has bad checksum %02x\n",
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BIOS_SEG, offset, sum );
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continue;
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}
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/* Fill result structure */
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DBG ( "Found SMBIOS entry point at %04x:%04x\n",
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BIOS_SEG, offset );
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memcpy ( entry, &u.entry, sizeof ( *entry ) );
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return 0;
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}
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DBG ( "No SMBIOS found\n" );
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return -ENOENT;
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}
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/**
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* Find specific structure type within SMBIOS
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*
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* @v entry SMBIOS entry point
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* @v type Structure type
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* @v data SMBIOS structure buffer to fill in
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* @ret rc Return status code
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*
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* The buffer must be at least @c entry->max bytes in size.
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*/
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static int find_smbios ( struct smbios_entry *entry, unsigned int type,
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void *data ) {
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struct smbios *smbios = data;
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userptr_t smbios_address = phys_to_user ( entry->smbios_address );
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unsigned int count = 0;
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size_t offset = 0;
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size_t frag_len;
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void *end;
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while ( ( offset < entry->smbios_length ) &&
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( count < entry->smbios_count ) ) {
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/* Read next SMBIOS structure */
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frag_len = ( entry->smbios_length - offset );
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if ( frag_len > entry->max )
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frag_len = entry->max;
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copy_from_user ( data, smbios_address, offset, frag_len );
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/* Sanity protection; ensure the last two bytes of the
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* buffer are 0x00,0x00, just so that a terminator
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* exists somewhere. Also ensure that this lies
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* outside the formatted area.
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*/
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*( ( uint16_t * ) ( data + entry->max - 2 ) ) = 0;
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if ( smbios->length > ( entry->max - 2 ) ) {
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DBG ( "Invalid SMBIOS structure length %zd\n",
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smbios->length );
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return -ENOENT;
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}
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DBG ( "Found SMBIOS structure type %d at offset %zx\n",
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smbios->type, offset );
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/* If this is the structure we want, return */
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if ( smbios->type == type )
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return 0;
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/* Find end of record. This will always exist, thanks
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* to our sanity check above.
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*/
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for ( end = ( data + smbios->length ) ;
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end < ( data + entry->max ) ; end++ ) {
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if ( *( ( uint16_t * ) end ) == 0 ) {
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end += 2;
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break;
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}
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}
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offset += ( end - data );
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count++;
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}
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DBG ( "SMBIOS structure type %d not found\n", type );
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return -ENOENT;
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}
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/**
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* Find indexed string within SMBIOS structure
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*
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* @v data SMBIOS structure
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* @v index String index
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* @ret string String, or NULL
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*/
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static const char * find_smbios_string ( void *data, unsigned int index ) {
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struct smbios *smbios = data;
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const char *string;
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size_t len;
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if ( ! index )
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return NULL;
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string = ( data + smbios->length );
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while ( --index ) {
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/* Move to next string */
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len = strlen ( string );
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if ( len == 0 ) {
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/* Reached premature end of string table */
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DBG ( "SMBIOS string index %d not found\n", index );
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return NULL;
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}
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string += ( len + 1 );
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}
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return string;
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}
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/**
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* Find SMBIOS serial number
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*
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* @v data Buffer to fill
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* @v len Length of buffer
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*/
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int find_smbios_serial ( void *data, size_t len ) {
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struct smbios_entry entry;
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const char *string;
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int rc;
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if ( ( rc = find_smbios_entry ( &entry ) ) != 0 )
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return rc;
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char buffer[entry.max];
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if ( ( rc = find_smbios ( &entry, 1, buffer ) ) != 0 )
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return rc;
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struct smbios_system_information *sysinfo = ( void * ) buffer;
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string = find_smbios_string ( buffer, sysinfo->serial );
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if ( ! string )
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return -ENOENT;
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DBG ( "Found serial number \"%s\"\n", string );
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snprintf ( data, len, "%s", string );
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return 0;
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}
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@ -0,0 +1,11 @@
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#ifndef _SMBIOS_H
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#define _SMBIOS_H
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/** @file
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*
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* System Management BIOS
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*/
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extern int find_smbios_serial ( void *data, size_t len );
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#endif /* _SMBIOS_H */
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