loader/dos/dosmod.c

   1 /*
   2  * DOS Virtual Machine
   3  *
   4  * Copyright 1998 Ove Kåven
   5  */
   6
   7 #if defined(linux) && defined(__i386__)
   8
   9 /* apparently ELF images are usually loaded high anyway */
  10 #ifndef __ELF__
  11 /* if not, force dosmod at high addresses */
  12 asm(".org 0x110000");
  13 #endif __ELF__
  14
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18 #include <errno.h>
  19 #include <unistd.h>
  20 #include <fcntl.h>
  21 #include <signal.h>
  22 #include <sys/stat.h>
  23 #include <sys/mman.h>
  24 #include <sys/vm86.h>
  25 #include <sys/time.h>
  26 #include <sys/types.h>
  27 #include <sys/ptrace.h>
  28 #include <sys/wait.h>
  29 #include "dosmod.h"
  30
  31  /* FIXME: hack because libc vm86 may be the old syscall version */
  32
  33 #define SYS_vm86   166
  34
  35 static __inline__ int vm86plus( int func, struct vm86plus_struct *ptr )
  36 {
  37     int res;
  38 #ifdef __PIC__
  39     __asm__ __volatile__( "pushl %%ebx\n\t"
  40                           "movl %2,%%ebx\n\t"
  41                           "int $0x80\n\t"
  42                           "popl %%ebx"
  43                           : "=a" (res)
  44                           : "0" (SYS_vm86),
  45                             "g" (func),
  46                             "c" (ptr) );
  47 #else
  48     __asm__ __volatile__("int $0x80"
  49                          : "=a" (res)
  50                          : "0" (SYS_vm86),
  51                            "b" (func),
  52                            "c" (ptr) );
  53 #endif  /* __PIC__ */
  54     if (res >= 0) return res;
  55     errno = -res;
  56     return -1;
  57 }
  58
  59 void set_timer(struct timeval*tim)
  60 {
  61  struct itimerval cur;
  62
  63  cur.it_interval=*tim;
  64  cur.it_value=*tim;
  65  setitimer(ITIMER_REAL,&cur,NULL);
  66 }
  67
  68 volatile int sig_pend,sig_fatal=0;
  69 void*img;
  70 struct vm86plus_struct VM86;
  71
  72 void sig_handler(int sig)
  73 {
  74  if (sig_pend) fprintf(stderr,"DOSMOD previous signal %d lost\n",sig_pend);
  75  sig_pend=sig;
  76  signal(sig,sig_handler);
  77 }
  78
  79 void bad_handler(int sig)
  80 {
  81  fprintf(stderr,"DOSMOD caught fatal signal %d\n",sig);
  82  fprintf(stderr,"(Last known VM86 CS:IP was %04x:%04lx)\n",VM86.regs.cs,VM86.regs.eip);
  83  sig_pend=sig; sig_fatal++;
  84  signal(sig,bad_handler);
  85 }
  86
  87 int main(int argc,char**argv)
  88 {
  89  int mfd=open(argv[0],O_RDWR);
  90  struct timeval tim;
  91  int func,ret;
  92  off_t fofs=0;
  93  pid_t ppid=getppid();
  94
  95 /* fprintf(stderr,"main is at %08lx, file is %s, fd=%d\n",(unsigned long)&main,argv[0],mfd); */
  96  if (mfd<0) return 1;
  97 /* Map in our DOS image at the start of the process address space */
  98  if (argv[1]) {
  99   /* Ulrich Weigand suggested mapping in the DOS image directly from the Wine
 100      address space */
 101   fofs=atol(argv[1]);
 102   /* linux currently only allows mapping a process memory if it's being ptraced */
 103   /* Linus doesn't like it, so this probably won't work in the future */
 104   /* it doesn't even work for me right now */
 105   kill(ppid,SIGSTOP);
 106   ptrace(PTRACE_ATTACH,ppid,0,0);
 107   waitpid(ppid,NULL,0);
 108  }
 109  img=mmap(NULL,0x110000,PROT_EXEC|PROT_READ|PROT_WRITE,MAP_FIXED|MAP_SHARED,mfd,fofs);
 110  if (argv[1]) {
 111   ptrace(PTRACE_DETACH,ppid,0,0);
 112   kill(ppid,SIGCONT);
 113  }
 114  if (img==(void*)-1) {
 115   fprintf(stderr,"DOS memory map failed, error=%s\n",strerror(errno));
 116   fprintf(stderr,"in attempt to map %s, offset %08lX, length 110000, to offset 0\n",argv[0],fofs);
 117   return 1;
 118  }
 119 /* initialize signals and system timer */
 120  signal(SIGHUP,sig_handler);
 121  signal(SIGINT,sig_handler);
 122  signal(SIGUSR1,sig_handler);
 123  signal(SIGUSR2,sig_handler);
 124  signal(SIGALRM,sig_handler);
 125
 126  signal(SIGQUIT,bad_handler);
 127  signal(SIGILL,bad_handler);
 128  signal(SIGBUS,bad_handler);
 129  signal(SIGFPE,bad_handler);
 130  signal(SIGSEGV,bad_handler);
 131  signal(SIGTERM,bad_handler);
 132 #if 0
 133  tim.tv_sec=0; tim.tv_usec=54925;
 134  set_timer(&tim);
 135 #endif
 136 /* report back to the main program that we're ready */
 137  ret=1; /* dosmod protocol revision 1 */
 138  write(1,&ret,sizeof(ret));
 139 /* context exchange loop */
 140  do {
 141   if (read(0,&func,sizeof(func))!=sizeof(func)) return 1;
 142   if (func<0) break;
 143   switch (func) {
 144    case DOSMOD_SET_TIMER:
 145     if (read(0,&tim,sizeof(tim))!=sizeof(tim)) return 1;
 146     set_timer(&tim);
 147     /* no response */
 148     break;
 149    case DOSMOD_ENTER:
 150    default:
 151     if (read(0,&VM86,sizeof(VM86))!=sizeof(VM86)) return 1;
 152     if (sig_pend) ret=DOSMOD_SIGNAL; else
 153      ret=vm86plus(func,&VM86);
 154     if (write(1,&ret,sizeof(ret))!=sizeof(ret)) return 1;
 155     if (write(1,&VM86,sizeof(VM86))!=sizeof(VM86)) return 1;
 156     switch (ret&0xff) {
 157      case DOSMOD_SIGNAL:
 158       ret=sig_pend; sig_pend=0;
 159       if (write(1,&ret,sizeof(ret))!=sizeof(ret)) return 1;
 160       if (sig_fatal) return 1;
 161       break;
 162     }
 163   }
 164  } while (1);
 165  return 0;
 166 }
 167
 168 #else /* !linux-i386 */
 169 int main(void) {return 1;}
 170 #endif