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 #include "config.h"
  10
  11 /* apparently ELF images are usually loaded high anyway */
  12 #ifndef __ELF__
  13 /* if not, force dosmod at high addresses */
  14 asm(".org 0x110000");
  15 #endif /* __ELF__ */
  16
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <string.h>
  20 #include <errno.h>
  21 #include <unistd.h>
  22 #include <fcntl.h>
  23 #include <signal.h>
  24 #include <sys/stat.h>
  25 #ifdef HAVE_SYS_MMAN_H
  26 # include <sys/mman.h>
  27 #endif
  28 #ifdef HAVE_SYS_VM86_H
  29 # include <sys/vm86.h>
  30 #endif
  31 #include <sys/time.h>
  32 #include <sys/types.h>
  33 #include <sys/ptrace.h>
  34 #ifdef HAVE_SYS_WAIT_H
  35 # include <sys/wait.h>
  36 #endif
  37 #include "dosmod.h"
  38
  39  /* FIXME: hack because libc vm86 may be the old syscall version */
  40
  41 #define SYS_vm86   166
  42
  43 static inline int vm86plus( int func, struct vm86plus_struct *ptr )
  44 {
  45     int res;
  46 #ifdef __PIC__
  47     __asm__ __volatile__( "pushl %%ebx\n\t"
  48                           "movl %2,%%ebx\n\t"
  49                           "int $0x80\n\t"
  50                           "popl %%ebx"
  51                           : "=a" (res)
  52                           : "0" (SYS_vm86),
  53                             "g" (func),
  54                             "c" (ptr) );
  55 #else
  56     __asm__ __volatile__("int $0x80"
  57                          : "=a" (res)
  58                          : "0" (SYS_vm86),
  59                            "b" (func),
  60                            "c" (ptr) );
  61 #endif  /* __PIC__ */
  62     if (res >= 0) return res;
  63     errno = -res;
  64     return -1;
  65 }
  66
  67 int XREAD(int fd,void*buf,int size) {
  68  int res;
  69
  70  while (1) {
  71   res = read(fd, buf, size);
  72   if (res==size)
  73    return res;
  74   if (res==-1) {
  75    if (errno==EINTR)
  76     continue;
  77    perror("dosmod read");
  78    return -1;
  79   }
  80   if (res) /* don't print the EOF condition */
  81    fprintf(stderr,"dosmod read only %d of %d bytes.\n",res,size);
  82   return res;
  83  }
  84 }
  85 int XWRITE(int fd,void*buf,int size) {
  86  int res;
  87
  88  while (1) {
  89   res = write(fd, buf, size);
  90   if (res==size)
  91    return res;
  92   if (res==-1) {
  93    if (errno==EINTR)
  94     continue;
  95    perror("dosmod write");
  96    return -1;
  97   }
  98   fprintf(stderr,"dosmod write only %d of %d bytes.\n",res,size);
  99   return res;
 100  }
 101 }
 102
 103 void set_timer(struct timeval*tim)
 104 {
 105  struct itimerval cur;
 106
 107  cur.it_interval=*tim;
 108  cur.it_value=*tim;
 109  setitimer(ITIMER_REAL,&cur,NULL);
 110 }
 111
 112 void get_timer(struct timeval*tim)
 113 {
 114  struct itimerval cur;
 115
 116  getitimer(ITIMER_REAL,&cur);
 117  *tim=cur.it_value;
 118 }
 119
 120 volatile int sig_pend,sig_fatal=0,sig_alrm=0,sig_cb=0;
 121 void*img;
 122 struct vm86plus_struct VM86;
 123
 124 void sig_handler(int sig)
 125 {
 126  if (sig_pend) fprintf(stderr,"DOSMOD previous signal %d lost\n",sig_pend);
 127  sig_pend=sig;
 128  signal(sig,sig_handler);
 129 }
 130
 131 void bad_handler(int sig)
 132 {
 133  if (sig!=SIGTERM) {
 134   fprintf(stderr,"DOSMOD caught fatal signal %d\n",sig);
 135   fprintf(stderr,"(Last known VM86 CS:IP was %04x:%04lx)\n",VM86.regs.cs,VM86.regs.eip);
 136  }
 137  sig_pend=sig; sig_fatal++;
 138  signal(sig,bad_handler);
 139 }
 140
 141 void alarm_handler(int sig)
 142 {
 143  sig_alrm++;
 144  signal(sig,alarm_handler);
 145 }
 146
 147 void cb_handler(int sig)
 148 {
 149  sig_cb++;
 150  signal(sig,cb_handler);
 151 }
 152
 153 int send_signal(void)
 154 {
 155  int ret=sig_pend; sig_pend=0;
 156  if (!ret) {
 157   if (sig_alrm) {
 158    ret=SIGALRM; sig_alrm--;
 159   } else {
 160    ret=SIGUSR2; sig_cb--;
 161   }
 162  }
 163  if (XWRITE(1,&ret,sizeof(ret))!=sizeof(ret)) return 1;
 164  if (sig_fatal) return 1;
 165  return 0;
 166 }
 167
 168 int send_enter_reply(int ret)
 169 {
 170  if (XWRITE(1,&ret,sizeof(ret))!=sizeof(ret)) return 1;
 171  if (XWRITE(1,&VM86,sizeof(VM86))!=sizeof(VM86)) return 1;
 172  switch (ret&0xff) {
 173   case DOSMOD_SIGNAL:
 174    return send_signal();
 175  }
 176  return 0;
 177 }
 178
 179 int main(int argc,char**argv)
 180 {
 181  int mfd=open(argv[0],O_RDWR);
 182  struct timeval tim;
 183  mprot_info mpr;
 184  int func,ret,idle;
 185  off_t fofs=0;
 186  pid_t ppid=getppid();
 187
 188 /* fprintf(stderr,"main is at %08lx, file is %s, fd=%d\n",(unsigned long)&main,argv[0],mfd); */
 189  if (mfd<0) return 1;
 190 /* Map in our DOS image at the start of the process address space */
 191  if (argv[1]) {
 192   /* Ulrich Weigand suggested mapping in the DOS image directly from the Wine
 193      address space */
 194   fofs=atol(argv[1]);
 195   /* linux currently only allows mapping a process memory if it's being ptraced */
 196   /* Linus doesn't like it, so this probably won't work in the future */
 197   /* it doesn't even work for me right now */
 198   kill(ppid,SIGSTOP);
 199   ptrace(PTRACE_ATTACH,ppid,0,0);
 200   waitpid(ppid,NULL,0);
 201  }
 202  img=mmap(NULL,0x110000,PROT_EXEC|PROT_READ|PROT_WRITE,MAP_FIXED|MAP_SHARED,mfd,fofs);
 203  if (argv[1]) {
 204   ptrace(PTRACE_DETACH,ppid,0,0);
 205   kill(ppid,SIGCONT);
 206  }
 207  if (img==(void*)-1) {
 208   fprintf(stderr,"DOS memory map failed, error=%s\n",strerror(errno));
 209   fprintf(stderr,"in attempt to map %s, offset %08lX, length 110000, to offset 0\n",argv[0],fofs);
 210   return 1;
 211  }
 212 /* initialize signals and system timer */
 213  signal(SIGHUP,sig_handler);
 214  signal(SIGINT,sig_handler);
 215  signal(SIGUSR1,sig_handler);
 216  signal(SIGUSR2,cb_handler);
 217  signal(SIGALRM,alarm_handler);
 218
 219  signal(SIGQUIT,bad_handler);
 220  signal(SIGILL,bad_handler);
 221  signal(SIGBUS,bad_handler);
 222  signal(SIGFPE,bad_handler);
 223  signal(SIGSEGV,bad_handler);
 224  signal(SIGTERM,bad_handler);
 225 #if 0
 226  tim.tv_sec=0; tim.tv_usec=54925;
 227  set_timer(&tim);
 228 #endif
 229 /* report back to the main program that we're ready */
 230  ret=3; /* dosmod protocol revision */
 231  XWRITE(1,&ret,sizeof(ret));
 232 /* context exchange loop */
 233  idle=0;
 234  do {
 235   if (idle) {
 236    while (1) {
 237     int res;
 238     /* parent is idle, transmit any signals (particularly SIGALRM) */
 239     if (sig_pend||sig_alrm||sig_cb) {
 240      ret=DOSMOD_SIGNAL;
 241      if (XWRITE(1,&ret,sizeof(ret))!=sizeof(ret)) return 1;
 242      ret=send_signal();
 243      if (ret) return ret;
 244      break;
 245     }
 246     res = read(0,&func,sizeof(func));
 247     if (res==sizeof(func))
 248      break;
 249     if (res==-1) {
 250      if (errno==EINTR)
 251       continue;
 252      perror("dosmod read");
 253      return 1;
 254     }
 255     if (res) /* don't print the EOF condition */
 256      fprintf(stderr,"dosmod read only %d of %d bytes.\n",res,sizeof(func));
 257     return 1;
 258    }
 259    ret=DOSMOD_LEFTIDLE;
 260    if (XWRITE(1,&ret,sizeof(ret))!=sizeof(ret)) return 1;
 261    idle--;
 262   } else
 263    if (XREAD(0,&func,sizeof(func))!=sizeof(func)) return 1;
 264   if (func<0) break;
 265   switch (func) {
 266    case DOSMOD_SET_TIMER: /* rev 1 */
 267     if (XREAD(0,&tim,sizeof(tim))!=sizeof(tim)) return 1;
 268     set_timer(&tim);
 269     /* no response */
 270     break;
 271    case DOSMOD_GET_TIMER: /* rev 1 */
 272     get_timer(&tim);
 273     if (XWRITE(1,&tim,sizeof(tim))!=sizeof(tim)) return 1;
 274     break;
 275    case DOSMOD_MPROTECT: /* rev 3 */
 276     if (XREAD(0,&mpr,sizeof(mpr))!=sizeof(mpr)) return 1;
 277     mprotect(mpr.addr,mpr.len,mpr.prot);
 278     /* no response */
 279     break;
 280    case DOSMOD_ENTERIDLE: /* rev 3 */
 281     idle++;
 282     break;
 283    case DOSMOD_LEAVEIDLE: /* rev 3 */
 284     break;
 285    case DOSMOD_ENTER: /* rev 0 */
 286    default:
 287     if (XREAD(0,&VM86,sizeof(VM86))!=sizeof(VM86)) return 1;
 288     if (sig_pend||sig_alrm||sig_cb) ret=DOSMOD_SIGNAL; else
 289      ret=vm86plus(func,&VM86);
 290
 291     ret=send_enter_reply(ret);
 292     if (ret) return ret;
 293   }
 294  } while (1);
 295  return 0;
 296 }
 297
 298 #else /* !linux-i386 */
 299 int main(void) {return 1;}
 300 #endif