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/* $Id: biossums.c $ */
/** @file
* Tool for modifying a BIOS image to write the BIOS checksum.
*/
/*
* Copyright (C) 2006-2020 Oracle Corporation
*
* This file is part of VirtualBox Open Source Edition (OSE), as
* available from http://www.virtualbox.org. This file is free software;
* you can redistribute it and/or modify it under the terms of the GNU
* General Public License (GPL) as published by the Free Software
* Foundation, in version 2 as it comes in the "COPYING" file of the
* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <stdarg.h>
#include <errno.h>
#ifndef RT_OS_WINDOWS
# include <unistd.h> /* unlink */
#endif
typedef unsigned char uint8_t;
static uint8_t abBios[64*1024];
static FILE *g_pIn = NULL;
static FILE *g_pOut = NULL;
static const char *g_pszOutFile = NULL;
static const char *g_argv0;
/**
* Find where the filename starts in the given path.
*/
static const char *name(const char *pszPath)
{
const char *psz = strrchr(pszPath, '/');
#if defined(_MSC_VER) || defined(__OS2__)
const char *psz2 = strrchr(pszPath, '\\');
if (!psz2)
psz2 = strrchr(pszPath, ':');
if (psz2 && (!psz || psz2 > psz))
psz = psz2;
#endif
return psz ? psz + 1 : pszPath;
}
/**
* Report an error.
*/
static int fatal(const char *pszFormat, ...)
{
va_list va;
fprintf(stderr, "%s: ", name(g_argv0));
va_start(va, pszFormat);
vfprintf(stderr, pszFormat, va);
va_end(va);
/* clean up */
if (g_pIn)
fclose(g_pIn);
if (g_pOut)
fclose(g_pOut);
if (g_pszOutFile)
unlink(g_pszOutFile);
return 1;
}
/**
* Calculate the checksum.
*/
static uint8_t calculateChecksum(uint8_t *pb, size_t cb, size_t iChecksum)
{
uint8_t u8Sum = 0;
size_t i;
for (i = 0; i < cb; i++)
if (i != iChecksum)
u8Sum += pb[i];
return -u8Sum;
}
/**
* Find a header in the binary.
*
* @param pb Where to search for the signature
* @param cb Size of the search area
* @param pbHeader Pointer to the start of the signature
* @returns 0 if signature was not found, 1 if found or
* 2 if more than one signature was found */
static int searchHeader(uint8_t *pb, size_t cb, const char *pszHeader, uint8_t **pbHeader)
{
int fFound = 0;
unsigned int i;
size_t cbSignature = strlen(pszHeader);
for (i = 0; i < cb; i += 16)
if (!memcmp(pb + i, pszHeader, cbSignature))
{
if (fFound++)
return 2;
*pbHeader = pb + i;
}
return fFound;
}
int main(int argc, char **argv)
{
FILE *pIn, *pOut;
size_t cbIn, cbOut;
int fAdapterBios = 0;
g_argv0 = argv[0];
if (argc != 3)
return fatal("Input file name and output file name required.\n");
pIn = g_pIn = fopen(argv[1], "rb");
if (!pIn)
return fatal("Error opening '%s' for reading (%s).\n", argv[1], strerror(errno));
pOut = g_pOut = fopen(argv[2], "wb");
if (!pOut)
return fatal("Error opening '%s' for writing (%s).\n", argv[2], strerror(errno));
g_pszOutFile = argv[2];
/* safety precaution (aka. complete paranoia :-) */
memset(abBios, 0, sizeof(abBios));
cbIn = fread(abBios, 1, sizeof(abBios), pIn);
if (ferror(pIn))
return fatal("Error reading from '%s' (%s).\n", argv[1], strerror(errno));
g_pIn = NULL;
fclose(pIn);
fAdapterBios = abBios[0] == 0x55 && abBios[1] == 0xaa;
/* align size to page size */
if ((cbIn % 4096) != 0)
cbIn = (cbIn + 4095) & ~4095;
if (!fAdapterBios && cbIn != 64*1024)
return fatal("Size of system BIOS is not 64KB!\n");
if (fAdapterBios)
{
/* adapter BIOS */
/* set the length indicator */
abBios[2] = (uint8_t)(cbIn / 512);
}
else
{
/* system BIOS */
size_t cbChecksum;
uint8_t u8Checksum;
uint8_t *pbHeader;
/* Set the BIOS32 header checksum. */
switch (searchHeader(abBios, cbIn, "_32_", &pbHeader))
{
case 0:
return fatal("No BIOS32 header not found!\n");
case 2:
return fatal("More than one BIOS32 header found!\n");
case 1:
cbChecksum = (size_t)pbHeader[9] * 16;
u8Checksum = calculateChecksum(pbHeader, cbChecksum, 10);
pbHeader[10] = u8Checksum;
break;
}
/* Set the PIR header checksum according to PCI IRQ Routing table
* specification version 1.0, Microsoft Corporation, 1996 */
switch (searchHeader(abBios, cbIn, "$PIR", &pbHeader))
{
case 0:
return fatal("No PCI IRQ routing table found!\n");
case 2:
return fatal("More than one PCI IRQ routing table found!\n");
case 1:
cbChecksum = (size_t)pbHeader[6] + (size_t)pbHeader[7] * 256;
u8Checksum = calculateChecksum(pbHeader, cbChecksum, 31);
pbHeader[31] = u8Checksum;
break;
}
/* Set the SMBIOS header checksum according to System Management BIOS
* Reference Specification Version 2.5, DSP0134. */
switch (searchHeader(abBios, cbIn, "_SM_", &pbHeader))
{
case 0:
return fatal("No SMBIOS header found!\n");
case 2:
return fatal("More than one SMBIOS header found!\n");
case 1:
/* at first fix the DMI header starting at SMBIOS header offset 16 */
u8Checksum = calculateChecksum(pbHeader+16, 15, 5);
pbHeader[21] = u8Checksum;
/* now fix the checksum of the whole SMBIOS header */
cbChecksum = (size_t)pbHeader[5];
u8Checksum = calculateChecksum(pbHeader, cbChecksum, 4);
pbHeader[4] = u8Checksum;
break;
}
}
/* set the BIOS checksum */
abBios[cbIn-1] = calculateChecksum(abBios, cbIn, cbIn - 1);
cbOut = fwrite(abBios, 1, cbIn, pOut);
if (ferror(pOut))
return fatal("Error writing to '%s' (%s).\n", g_pszOutFile, strerror(errno));
g_pOut = NULL;
if (fclose(pOut))
return fatal("Error closing '%s' (%s).\n", g_pszOutFile, strerror(errno));
return 0;
}
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