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