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/*
* patch-cmdline.c - patch the kernel command line
*
* Copyright (C) 2006 Felix Fietkau <nbd@nbd.name>
*
* 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; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <string.h>
#define SEARCH_SPACE (16 * 1024)
#define CMDLINE_MAX 512
int main(int argc, char **argv)
{
int fd, found = 0, len, ret = -1;
char *ptr, *p;
unsigned int search_space;
if (argc <= 2 || argc > 4) {
fprintf(stderr, "Usage: %s <file> <cmdline> [size]\n", argv[0]);
goto err1;
} else if (argc == 3) {
fprintf(stdout, "search space used is default of 16KB\n");
search_space = SEARCH_SPACE;
} else {
search_space = atoi(argv[3]);
}
len = strlen(argv[2]);
if (len + 9 > CMDLINE_MAX) {
fprintf(stderr, "Command line string too long\n");
goto err1;
}
if (((fd = open(argv[1], O_RDWR)) < 0) ||
(ptr = (char *) mmap(0, search_space + CMDLINE_MAX, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0)) == (void *) (-1)) {
fprintf(stderr, "Could not open kernel image");
goto err2;
}
for (p = ptr; p < (ptr + search_space); p += 4) {
if (memcmp(p, "CMDLINE:", 8) == 0) {
found = 1;
p += 8;
break;
}
}
if (!found) {
fprintf(stderr, "Command line marker not found!\n");
goto err3;
}
memset(p, 0, CMDLINE_MAX - 8);
strcpy(p, argv[2]);
msync(p, CMDLINE_MAX, MS_SYNC|MS_INVALIDATE);
ret = 0;
err3:
munmap((void *) ptr, len);
err2:
if (fd > 0)
close(fd);
err1:
return ret;
}
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