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util-linux/mkzimage_cmdline.c

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/* $Id: mkzimage_cmdline.c 590 2006-02-07 14:38:07Z jplack $ */
/*
* a little tool to modify the cmdline inside a zImage
* Olaf Hering <olh@suse.de> Copyright (C) 2003, 2004
*/
/*
2003-10-02, version 1
2003-11-15, version 2: fix short reads if the string is at the end of the file
2004-08-07, version 3: use mmap
*/
/*
* 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
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>
#define MY_VERSION 3
static int activate;
static int clear;
static int set;
static char *string;
static char *filename;
static const char cmdline_start[] = "cmd_line_start";
static const char cmdline_end[] = "cmd_line_end";
static void my_version(void)
{
printf("version: %d\n", MY_VERSION);
printf("(C) SuSE Linux AG, Nuernberg, Germany, 2003, 2004\n");
return;
}
static void my_rtfm(const char *app)
{
printf("modify the built-in cmdline of a CHRP boot image\n");
printf("%s filename\n", app);
printf("work with zImage named 'filename'\n");
printf(" [-h] display this help\n");
printf(" [-v] display version\n");
printf(" [-a 0|1] disable/enable built-in cmdline\n");
printf(" overrides whatever is passed from OpenFirmware\n");
printf(" [-s STRING] store STRING in the boot image\n");
printf(" [-c] clear previous content before update\n");
printf(" no option will show the current settings in 'filename'\n");
return;
}
int main(int argc, char **argv)
{
struct stat sb;
int fd, found;
unsigned char *p, *s, *e, *tmp, *active;
if (argc < 2) {
my_rtfm(argv[0]);
exit(1);
}
while (1) {
int i;
i = getopt(argc, argv, "a:hcvs:");
if (i == -1)
break;
switch (i) {
case 'a':
if (*optarg == '0')
activate = -1;
else
activate = 1;
break;
case 'c':
clear = 1;
break;
case 'h':
my_rtfm(argv[0]);
exit(0);
case 's':
string = strdup(optarg);
if (!string) {
fprintf(stderr, "set: no mem\n");
exit(1);
}
set = 1;
break;
case 'v':
my_version();
exit(0);
default:
printf("unknown option\n");
my_rtfm(argv[0]);
exit(1);
}
}
if (argc <= optind) {
fprintf(stderr, "filename required\n");
exit(1);
}
filename = strdup(argv[optind]);
if (!filename) {
fprintf(stderr, "no mem\n");
exit(1);
}
fd = open(filename, (activate || clear || set) ? O_RDWR : O_RDONLY);
if (fd == -1)
goto error;
found = stat(filename, &sb);
if (found < 0)
goto error;
if (!S_ISREG(sb.st_mode)) {
fprintf(stderr, "%s is not a file\n", filename);
exit(1);
}
p = mmap(NULL, sb.st_size,
((activate || clear || set) ?
PROT_WRITE : 0) | PROT_READ, MAP_SHARED, fd, 0);
if (p == MAP_FAILED)
goto error;
s = p;
e = p + sb.st_size - sizeof(cmdline_start) - sizeof(cmdline_end);
found = 0;
while (s < e) {
if (memcmp(++s, cmdline_start, sizeof(cmdline_start) - 1) != 0)
continue;
found = 1;
break;
}
if (!found)
goto no_start;
found = 0;
active = s - 1;
tmp = s = s + sizeof(cmdline_start) - 1;
e = p + sb.st_size - sizeof(cmdline_end);
while (tmp < e) {
if (memcmp(++tmp, cmdline_end, sizeof(cmdline_end)) != 0)
continue;
found = 1;
break;
}
if (!found)
goto no_end;
if (activate || clear || set) {
if (activate)
*active = activate > 0 ? '1' : '0';
if (clear)
memset(s, 0x0, tmp - s);
if (set)
snprintf(s, tmp - s, "%s", string);
} else {
fprintf(stdout, "cmd_line size:%d\n", tmp - s);
fprintf(stdout, "cmd_line: %s\n", s);
fprintf(stdout, "active: %c\n", *active);
}
munmap(p, sb.st_size);
close(fd);
return 0;
error:
perror(filename);
return 1;
no_start:
fprintf(stderr, "%s: %s not found.\n", filename, cmdline_start);
return 1;
no_end:
fprintf(stderr, "%s: %s not found.\n", filename, cmdline_end);
return 1;
}