dc8b29f140
control program to control the facility of the bootblocks to fetch a default bootstring from a fixed location on the disk. See the manpage for more info.
233 lines
5.0 KiB
C
233 lines
5.0 KiB
C
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/*
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* Copyright (c) 1996 Whistle Communications
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* All Rights Reserved.
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*
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* Permission to use, copy, modify and distribute this software and its
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* documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* Whistle Communications allows free use of this software in its "as is"
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* condition. Whistle Communications disclaims any liability of any kind for
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* any damages whatsoever resulting from the use of this software.
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*/
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#include <sys/types.h>
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#include <sys/disklabel.h>
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#include <stdio.h>
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#include <string.h>
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#include <errno.h>
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#include <sys/stat.h>
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#include <sys/ioctl.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <unistd.h>
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struct mboot
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{
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unsigned char padding[2]; /* force the longs to be long alligned */
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unsigned char bootinst[DOSPARTOFF];
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struct dos_partition parts[4];
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unsigned short int signature;
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};
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struct mboot mboot;
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#define NAMEBLOCK 1 /* 2nd block */
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#define BLOCKSIZE 512
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#define ENABLE_MAGIC 0xdeafc0de
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#define DISABLE_MAGIC 0xdeadc0de
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static int bflag;
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static int eflag;
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static int dflag;
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static int nameblock = NAMEBLOCK;
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char * myname;
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#define BOOT_MAGIC 0xAA55
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static void usage(void) {
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printf (" usage: %s [-b] device bootstring [bootstring] ...\n"
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,myname);
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printf (" or: %s {-e,-d} device \n"
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,myname);
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printf (" flags are mutually exclusive\n");
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exit(1);
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}
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main (int argc, char** argv)
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{
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int fd = -1;
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char namebuf[1024], *cp = namebuf;
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int i,j;
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int ch;
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int part;
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bflag = 0;
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myname = argv[0];
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while ((ch = getopt(argc, argv, "bde")) != EOF) {
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switch(ch) {
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case 'b':
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bflag = 1;
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break;
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case 'd':
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dflag = 1;
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break;
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case 'e':
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eflag = 1;
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break;
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case '?':
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default:
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usage();
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}
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}
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argc -= optind;
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argv += optind;
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if ( (dflag + eflag + bflag) > 1 ) {
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usage();
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}
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if (dflag + eflag){
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if(argc != 1 ) {
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usage();
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}
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} else {
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if (argc <2) {
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usage();
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}
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}
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if ((fd = open(argv[0], O_RDWR, 0)) < 0) {
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perror("open");
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printf ("file: %s\n",argv[0]);
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usage();
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}
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argc--;
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argv++;
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/*******************************************
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* Check that we have an MBR
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*/
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if (lseek(fd,0,0) == -1) {
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perror("lseek");
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exit(1);
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}
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if (read (fd,&mboot.bootinst[0],BLOCKSIZE ) != BLOCKSIZE) {
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perror("read0");
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exit(1);
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}
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if(mboot.signature != (unsigned short)BOOT_MAGIC) {
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printf(" no fdisk part.. not touching block 1\n");
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exit(1);
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}
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/*******************************************
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* And check that none of the partitions in it cover the name block;
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*/
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for ( part = 0; part < 4; part++) {
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if( mboot.parts[part].dp_size
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&& (mboot.parts[part].dp_start <= NAMEBLOCK)
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&& (mboot.parts[part].dp_start
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+ mboot.parts[part].dp_size > NAMEBLOCK)) {
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printf(" Name sector lies within a Bios partition.\n");
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printf(" Aborting write.\n");
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exit(1);
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}
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}
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/*******************************************
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* Now check the name sector itself to see if it's been initialised.
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*/
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if (lseek(fd,NAMEBLOCK * BLOCKSIZE,0) == -1) {
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perror("lseek");
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exit(1);
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}
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if ( read (fd,namebuf,BLOCKSIZE ) != BLOCKSIZE) {
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perror("read1");
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exit(1);
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}
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/*******************************************
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* check if we are just enabling or disabling
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* Remember the flags are exlusive..
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*/
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if(!bflag) { /* don't care what's there if bflag is set */
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switch(*(unsigned long *)cp)
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{
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case DISABLE_MAGIC:
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case ENABLE_MAGIC:
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break;
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default:
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fprintf(stderr,
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"namesector not initialised.."
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"use the -b flag..\n");
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exit(1);
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}
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}
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/*******************************************
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* If the z or r flag is set, damage or restore the magic number..
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* to disable/enable the feature
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*/
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if(dflag) {
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*(unsigned long *)cp = DISABLE_MAGIC;
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} else {
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*(unsigned long *)cp = ENABLE_MAGIC;
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}
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if ((!dflag) && (!eflag)) {
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/*******************************************
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* Create a new namesector in ram
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*/
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cp += 4;
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for ( i = 0 ; i < argc ; i++ ) {
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*cp++ = 'D';
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*cp++ = 'N';
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j = strlen(argv[i]);
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strncpy(cp,argv[i],j);
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cp += j;
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*cp++ = 0;
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}
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*cp++ = 0xff;
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*cp++ = 0xff;
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*cp++ = 0xff;
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namebuf[BLOCKSIZE-1] = 0; /* paranoid */
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namebuf[BLOCKSIZE] = 0xff;
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}
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/*******************************************
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* write it to disk.
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*/
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if (lseek(fd,NAMEBLOCK * BLOCKSIZE,0) == -1) {
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perror("lseek");
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exit(1);
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}
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if(write (fd,namebuf,BLOCKSIZE ) != BLOCKSIZE) {
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perror("write");
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exit(1);
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}
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#if 0
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/*******************************************
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* just to be safe/paranoid.. read it back..
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* and print it..
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*/
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if (lseek(fd,NAMEBLOCK * BLOCKSIZE,0) == -1) {
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perror("lseek (second) ");
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exit(1);
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}
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read (fd,namebuf,512);
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for (i = 0;i< 16;i++) {
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for ( j = 0; j < 16; j++) {
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printf("%02x ",(unsigned char )namebuf[(i*16) + j ]);
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}
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printf("\n");
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}
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#endif
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exit(0);
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}
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