usr.bin/doscmd/doscmd_loader.c

   1 /*
   2  * Copyright (c) 1992, 1993, 1996
   3  *      Berkeley Software Design, Inc.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by Berkeley Software
  16  *      Design, Inc.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY Berkeley Software Design, Inc. ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL Berkeley Software Design, Inc. BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  *
  30  *      BSDI doscmd_loader.c,v 2.3 1996/04/08 19:32:33 bostic Exp
  31  *
  32  * $FreeBSD: src/usr.bin/doscmd/doscmd_loader.c,v 1.2.2.1 2002/04/25 11:04:51 tg Exp $
  33  * $DragonFly: src/usr.bin/doscmd/doscmd_loader.c,v 1.4 2004/01/22 04:22:52 rob Exp $
  34  */
  35
  36 #include <stdio.h>
  37 #include <stdlib.h>
  38 #include <a.out.h>
  39
  40 /*
  41  * reserve space in "low" memory for the interrupt vector table
  42  */
  43 static const char filler[4096] = { 0, };
  44
  45 #define _PATH_DOS_KERNEL_DIR    "/usr/libexec/"
  46 #define _PATH_DOS_KERNEL        "doscmd.kernel"
  47
  48 int
  49 load_kernel(void)
  50 {
  51     FILE *fp;
  52     struct exec exec;
  53     int start_address;
  54
  55     if ((fp = fopen(_PATH_DOS_KERNEL, "r")) == NULL &&
  56         (fp = fopen("obj/" _PATH_DOS_KERNEL, "r")) == NULL &&
  57         (fp = fopen(_PATH_DOS_KERNEL_DIR _PATH_DOS_KERNEL, "r")) == NULL &&
  58         (fp = fopen(getenv("DOS_KERNEL"), "r")) == NULL)
  59         err(1, "load_kernel");
  60
  61     if (fread(&exec, sizeof(exec), 1, fp) != 1 || N_GETMAGIC(exec) != OMAGIC)
  62         errx(1, "bad kernel file format");
  63
  64     start_address = exec.a_entry & (~(getpagesize() - 1));
  65     if (brk(start_address + exec.a_text + exec.a_data + exec.a_bss) < 0)
  66         err(1, "load_kernel");
  67     fread((char *)start_address, exec.a_text + exec.a_data, 1, fp);
  68     bzero((char *)(start_address + exec.a_text + exec.a_data), exec.a_bss);
  69     fclose(fp);
  70     return(exec.a_entry);
  71 }
  72
  73 void
  74 main(int argc, char **argv, char **environ)
  75 {
  76     void (*entry_point)();
  77 #ifndef __DragonFly__
  78     int fd = open("/dev/mem", 0);
  79 #endif
  80     setgid(getgid());
  81     setuid(getuid());
  82
  83 #ifndef __DragonFly__
  84     if (fd < 0)
  85         err(1, "/dev/mem");
  86 #endif
  87
  88     entry_point = (void (*)()) load_kernel();
  89
  90 #ifndef __DragonFly__
  91     if (read(fd, 0, 0x500 != 0x500))
  92         err(1, "/dev/mem");
  93
  94     close(fd);
  95 #endif
  96
  97     (*entry_point)(argc, argv, environ);
  98     errx(1, "return from doscmd kernel???");
  99 }