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/* $Id: piggyback.c,v 1.1.1.1 2004-04-15 01:33:53 phoenix Exp $

   Simple utility to make a single-image install kernel with initial ramdisk

   for Sparc64 tftpbooting without need to set up nfs.

   Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)

   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., 675 Mass Ave, Cambridge, MA 02139, USA.  */

#include <stdio.h>

#include <string.h>

#include <ctype.h>

#include <errno.h>

#include <fcntl.h>

#include <dirent.h>

#include <unistd.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/stat.h>

/* Note: run this on an a.out kernel (use elftoaout for it), as PROM looks for a.out image onlly

   usage: piggyback vmlinux System.map tail, where tail is gzipped fs of the initial ramdisk */

void die(char *str)

{

        perror (str);

        exit(1);

}

int main(int argc,char **argv)

{

        char buffer [1024], *q, *r;

        unsigned int i, j, k, start, end, offset;

        FILE *map;

        struct stat s;

        int image, tail;

        if (stat (argv[3], &s) < 0) die (argv[3]);

        map = fopen (argv[2], "r");

        if (!map) die(argv[2]);

        while (fgets (buffer, 1024, map)) {

                if (!strcmp (buffer + 19, "_start\n"))

                start = strtoul (buffer + 8, NULL, 16);

                else if (!strcmp (buffer + 19, "_end\n"))

                end = strtoul (buffer + 8, NULL, 16);

        }

        fclose (map);

        if ((image = open(argv[1],O_RDWR)) < 0) die(argv[1]);

        if (read(image,buffer,512) != 512) die(argv[1]);

        if (!memcmp (buffer, "\177ELF", 4)) {

                unsigned int *p = (unsigned int *)(buffer + *(unsigned int *)(buffer + 28));

                i = p[1] + *(unsigned int *)(buffer + 24) - p[2];

                if (lseek(image,i,0) < 0) die("lseek");

                if (read(image,buffer,512) != 512) die(argv[1]);

                j = 0;

        } else if (*(unsigned int *)buffer == 0x01030107) {

                i = j = 32;

        } else {

                fprintf (stderr, "Not ELF nor a.out. Don't blame me.\n");

                exit(1);

        }

        k = i;

        if (j == 32 && buffer[40] == 'H' && buffer[41] == 'd' && buffer[42] == 'r' && buffer[43] == 'S') {

                offset = 40 + 10;

        } else {

                i += ((*(unsigned short *)(buffer + j + 2))<<2) - 512;

                if (lseek(image,i,0) < 0) die("lseek");

                if (read(image,buffer,1024) != 1024) die(argv[1]);

                for (q = buffer, r = q + 512; q < r; q += 4) {

                        if (*q == 'H' && q[1] == 'd' && q[2] == 'r' && q[3] == 'S')

                                break;

                }

                if (q == r) {

                        fprintf (stderr, "Couldn't find headers signature in the kernel.\n");

                        exit(1);

                }

                offset = i + (q - buffer) + 10;

        }

        if (lseek(image, offset, 0) < 0) die ("lseek");

        *(unsigned *)buffer = 0;

        *(unsigned *)(buffer + 4) = 0x01000000;

        *(unsigned *)(buffer + 8) = ((end + 32 + 8191) & ~8191);

        *(unsigned *)(buffer + 12) = s.st_size;

        if (write(image,buffer+2,14) != 14) die (argv[1]);

        if (lseek(image, 4, 0) < 0) die ("lseek");

        *(unsigned *)buffer = ((end + 32 + 8191) & ~8191) - (start & ~0x3fffffUL) + s.st_size;

        *(unsigned *)(buffer + 4) = 0;

        *(unsigned *)(buffer + 8) = 0;

        if (write(image,buffer,12) != 12) die (argv[1]);

        if (lseek(image, k - start + ((end + 32 + 8191) & ~8191), 0) < 0) die ("lseek");

        if ((tail = open(argv[3],O_RDONLY)) < 0) die(argv[3]);

        while ((i = read (tail,buffer,1024)) > 0)

                if (write(image,buffer,i) != i) die (argv[1]);

        if (close(image) < 0) die("close");

        if (close(tail) < 0) die("close");

        return 0;

}