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/* SPDX-License-Identifier: MIT
*
* Copyright (c) 2022-2026 Leah Rowe <leah@libreboot.org>
*
* Functions related to GbE NVM checksums.
*
* Related file: word.c
*/
#ifdef __OpenBSD__
#include <sys/param.h>
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include "../include/common.h"
void
read_checksums(void)
{
struct xstate *x = xstatus();
struct commands *cmd;
struct xfile *f;
unsigned long _p;
unsigned long _skip_part;
unsigned char _num_invalid;
unsigned char _max_invalid;
cmd = &x->cmd[x->i];
f = &x->f;
f->part_valid[0] = 0;
f->part_valid[1] = 0;
if (!cmd->chksum_read)
return;
_num_invalid = 0;
_max_invalid = 2;
if (cmd->arg_part)
_max_invalid = 1;
/*
* Skip verification on this part,
* but only when arg_part is set.
*/
_skip_part = f->part ^ 1;
for (_p = 0; _p < 2; _p++) {
/*
* Only verify a part if it was *read*
*/
if (cmd->arg_part && (_p == _skip_part))
continue;
f->part_valid[_p] = good_checksum(_p);
if (!f->part_valid[_p])
++_num_invalid;
}
if (_num_invalid >= _max_invalid) {
if (_max_invalid == 1)
err(ECANCELED, "%s: part %lu has a bad checksum",
f->fname, (unsigned long)f->part);
err(ECANCELED, "%s: No valid checksum found in file",
f->fname);
}
}
int
good_checksum(unsigned long partnum)
{
unsigned short expected_checksum;
unsigned short actual_checksum;
expected_checksum =
calculated_checksum(partnum);
actual_checksum =
nvm_word(NVM_CHECKSUM_WORD, partnum);
if (expected_checksum == actual_checksum) {
return 1;
} else {
return 0;
}
}
void
set_checksum(unsigned long p)
{
check_bin(p, "part number");
set_nvm_word(NVM_CHECKSUM_WORD, p, calculated_checksum(p));
}
unsigned short
calculated_checksum(unsigned long p)
{
unsigned long c;
unsigned int val16;
val16 = 0;
for (c = 0; c < NVM_CHECKSUM_WORD; c++)
val16 += (unsigned int)nvm_word(c, p);
return (unsigned short)((NVM_CHECKSUM - val16) & 0xffff);
}
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