/**
 * $Id$
 *
 * Copyright (C) shinichiro.h <hamaji@nii.ac.jp>
 *  http://shinh.skr.jp/
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#include <stdio.h>
#include <string.h>

#include <sys/mman.h>

static void* reserved_byte;

int main(int argc, char* argv);

extern char _binary_COPYING_start[], _binary_COPYING_end[];

int gpl_main(int argc, char* argv[]) {
    char* m = (char*)main;
    void** ma = (void**)(m+1);
    int i;
    *ma = reserved_byte;
    mprotect((void*)(((int)m+4095)&~4095-4096), 4096,
             PROT_READ | PROT_EXEC);
    for (i = 1; i < argc; i++) {
        if (strcmp("--copying", argv[i]) == 0) {
            fwrite(_binary_COPYING_start, 1,
                   _binary_COPYING_end - _binary_COPYING_start, stdout);
            printf("\n");
            for (i++; i < argc; i++) {
                argv[i-1] = argv[i];
            }
            __asm__("subl $0x1, 0x8(%ebp)");
            goto jmp;
        }
    }

    /* is this too verbose? */
/*    printf("%s is free software, covered by the GNU General Public License,\nand you are welcome to change it and/or distribute copies of it under\ncertain conditions. There is absolutely no warranty for %s.\n\n", argv[0], argv[0]); */

jmp:
    __asm__("jmp *%0"::"g"(m+3));
}

void __attribute__ ((constructor)) gpl_init() {
    char* m = (char*)main;
    void** ma = (void**)(m+1);
    mprotect((void*)(((int)m+4095)&~4095-4096), 4096,
             PROT_READ | PROT_WRITE | PROT_EXEC);
    m[0] = 0xe9;
    reserved_byte = *ma;
    *ma = (void*)((int)gpl_main-(int)main-5);
}