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