dosexec.c

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/* Copyright (C) 2001 DJ Delorie, see COPYING.DJ for details */
/* Copyright (C) 2000 DJ Delorie, see COPYING.DJ for details */
/* Copyright (C) 1999 DJ Delorie, see COPYING.DJ for details */
/* Copyright (C) 1998 DJ Delorie, see COPYING.DJ for details */
/* Copyright (C) 1996 DJ Delorie, see COPYING.DJ for details */
/* Copyright (C) 1995 DJ Delorie, see COPYING.DJ for details */
#include <libc/stubs.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <signal.h>
#include <limits.h>
#include <fcntl.h>
#include <unistd.h>
#include <process.h>
#include <go32.h>
#include <dpmi.h>
#include <ctype.h>
#include <sys/system.h>
#include <sys/movedata.h>
#include <libc/dosexec.h>
#include <libc/unconst.h>
#include <libc/dosio.h>
#include <libc/farptrgs.h>

/* FIXME: this is not LFN-clean.  Win95 has a way to
   pass long command lines, but we don't support it here.  */
#define CMDLEN_LIMIT 125

extern char **environ;

int __dosexec_in_system = 0;

typedef struct {
  unsigned short eseg;
  unsigned short argoff;
  unsigned short argseg;
  unsigned short fcb1_off;
  unsigned short fcb1_seg;
  unsigned short fcb2_off;
  unsigned short fcb2_seg;
} Execp;

static Execp parm;

static unsigned long tbuf_ptr;
static unsigned long tbuf_beg;
static unsigned long tbuf_end;
static unsigned long tbuf_len;
#if 0
static int	     tbuf_selector;
#endif

static int script_exec(const char *, char **, char **);

/* Allocate AMT bytes off the transfer buffer.  */
static unsigned long talloc(size_t amt)
{
  unsigned long rv = tbuf_ptr;
  tbuf_ptr += amt;
  return rv;
}

/* Make sure we can allocate AMT bytes off the transfer buffer
   without overflowing it.  Return non-zero if we can, zero otherwise.

   WARNING: This can relocate the data already in the transfer buffer,
	    so all linear addresses which use it should be relative to
	    TBUF_BEG!  */
static int check_talloc(size_t amt)
{
  int retval = 1;

  if (tbuf_ptr + amt > tbuf_end)
  {
#if 0
    /* Code that reallocs the transfer buffer; currently disabled.  */
    unsigned long new_tb;
    unsigned long min_len = tbuf_len + amt;
    unsigned long max_len = 0x10000; /* 64KB */
    int old_selector = tbuf_selector;
    int max_avail;
    int e = errno;

    errno = E2BIG;

    /* Try to allocate new, larger DOS buffer, upto 64KB.  */
    if (min_len > max_len)
    {
      retval = 0;
      goto done;
    }
    while (tbuf_len <= max_len && tbuf_len < min_len)
      tbuf_len *= 2;
    if (tbuf_len < min_len)
    {
      retval = 0;
      goto done;
    }

    tbuf_len = (tbuf_len + 15) & 0xffff0; /* round to nearest paragraph */

    if ((new_tb =
	 __dpmi_allocate_dos_memory(tbuf_len/16, &max_avail)) == -1)
    {
      if (max_avail*16 < min_len
	  || (new_tb =
	      __dpmi_allocate_dos_memory(max_avail, &tbuf_selector)) == -1)
      {
	retval = 0;
	goto done;
      }
      tbuf_len = max_avail*16;
    }
    else
      tbuf_selector = max_avail;

    new_tb *= 16;  /* convert to linear address */
    movedata (_dos_ds, tbuf_beg, _dos_ds, new_tb, tbuf_ptr - tbuf_beg);
    tbuf_ptr = new_tb + tbuf_ptr - tbuf_beg;
    tbuf_beg = new_tb;
    tbuf_end = tbuf_beg + tbuf_len - 1;

    errno = e;

  done:
    /* Assume caller will return immediately in case of
       failure to reallocate, so they won't need the old data.  */
    if (!retval)
      tbuf_selector = 0;
    if (old_selector)
      __dpmi_free_dos_memory(old_selector);
#else
    errno = E2BIG;
    retval = 0;
#endif
  }

  return retval;
}

extern char   __PROXY[];	/* defined on crt0/crt1.c */
extern size_t __PROXY_LEN;

/* Functions that call `direct_exec_tail' after they've put
   some data into the transfer buffer, should set LFN parameter
   to either 0 (no LFN support) or 1 (LFN supported), but NOT 2!
   if LFN is 2, there is a possiblity that the contents of the
   transfer buffer will be overrun!  */
static int
direct_exec_tail(const char *program, const char *args,
		 char * const envp[], const char *proxy, int lfn)
{
  __dpmi_regs r;
  unsigned long program_la;
  unsigned long arg_la;
  unsigned long parm_la;
  unsigned long env_la, env_e_la;
  size_t proxy_len = proxy ? strlen(proxy)+1 : 0;
  int seen_proxy = 0;
  char arg_header[3];
  char short_name[FILENAME_MAX];
  const char *progname;
  unsigned proglen;
  int i;
  unsigned long fcb1_la, fcb2_la, fname_la;
  
  /* This used to just call sync().  But `sync' flushes the disk
     cache nowadays, and that can slow down the child tremendously,
     since some caches (e.g. SmartDrv) invalidate all of their
     buffers when `_flush_disk_cache' is called.  */
  for (i = 0; i < 255; i++)
    fsync(i);

  if (lfn == 2)		/* don't know yet */
    lfn = _USE_LFN;

  /* The pathname of the executable to run.  */
  proglen = strlen(program)+1;
  if (!check_talloc(proglen))
    return -1;
  /* Make sure any magic names, like /dev/c/foo, are converted to the
     usual DOS form, and, under LFN, to the short 8+3 alias.  */
  _put_path2(program, tbuf_beg == __tb ? tbuf_ptr - tbuf_beg : 0);
  if(lfn) {
    r.x.ax = 0x7160;			/* Truename */
    r.x.cx = 1;				/* Get short name */
    r.x.ds = r.x.es = tbuf_ptr / 16;
    r.x.si = r.x.di = tbuf_ptr & 15;
    __dpmi_int(0x21, &r);
    if (r.x.flags & 1)
    {
      errno = __doserr_to_errno(r.x.ax);
      return -1;
    }
  }
  dosmemget(tbuf_beg == __tb ? tbuf_ptr : __tb, FILENAME_MAX, short_name);
  progname = short_name;
  proglen = strlen(short_name)+1;

  if (!check_talloc(proglen + strlen(args) + 3 + sizeof(Execp) + 48))
    return -1;
  program_la = talloc(proglen);
  arg_la     = talloc(strlen(args)+3);
  parm_la    = talloc(sizeof(Execp));

  dosmemput(progname, proglen, program_la);

  /* The command-line tail.  */
  arg_header[0] = strlen(args);
  arg_header[1] = '\r';
  dosmemput(arg_header, 1, arg_la);
  dosmemput(args, strlen(args), arg_la+1);
  dosmemput(arg_header+1, 1, arg_la+1+strlen(args));

  /* The 2 FCBs.  Some programs (like XCOPY from DOS 6.x) need them.  */
  fcb1_la = talloc(16);	       /* allocate space for 1st FCB */
  fname_la = arg_la + 1;       /* first character of command tail */
  r.x.ax = 0x2901;	       /* AL = 1 means skip leading separators */
  r.x.ds = fname_la / 16;      /* pointer to 1st cmd argument */
  r.x.si = fname_la & 15;
  r.x.es = fcb1_la / 16;       /* pointer to FCB buffer */
  r.x.di = fcb1_la & 15;
  __dpmi_int (0x21, &r);

  /* We cannot be sure that Int 21h/AX=2901h parsed the entire
     first command-line argument (it might not be a filename
     at all!).  We need to get to the next command-line arg
     before calling 2901 again.  2901 returns the pointer to
     first unparsed character in DS:SI.

     Note that, in case there is no second command-line argument,
     the following loop is terminated by the trailing CR which
     ends the command-line tail.  */
  for (_farsetsel(_dos_ds), fname_la = ((unsigned)r.x.ds) * 16 + r.x.si;
       !isspace(_farnspeekb(fname_la));
       fname_la++)
    ;

  fcb2_la = talloc(16);
  r.x.ax = 0x2901;
  r.x.ds = fname_la / 16;      /* begin parsing 2nd arg from here */
  r.x.si = fname_la & 15;
  r.x.es = fcb2_la / 16;
  r.x.di = fcb2_la & 15;
  __dpmi_int (0x21, &r);

  /* The environment must be on a segment boundary, so get
     to the first location in the transfer buffer whose
     linear address is divisable by 16.  */
  do {
    env_la = talloc(1);
  } while (env_la & 15);
  talloc(-1);

#if 0
  /* Convert to relative, since `check_talloc' may relocate.  */
  arg_la  -= tbuf_beg;
  env_la  -= tbuf_beg;
  fcb1_la -= tbuf_beg;
  fcb2_la -= tbuf_beg;
  parm_la -= tbuf_beg;
  program_la -= tbuf_beg;
#endif

  /* The environment.  Replace the !proxy variable, if there is
     one (for nested programs) if we are called from `system',
     or skip it, if we are called from `spawnXX'.  */
  for (i=0; envp[i]; i++)
  {
    const char *ep = envp[i];
    size_t env_len = strlen(ep)+1;

    if (strncmp(ep, __PROXY, __PROXY_LEN) == 0 && ep[__PROXY_LEN] == '=')
    {
      seen_proxy = 1;
      if (proxy)
      {
	ep = proxy;
	env_len = proxy_len;
      }
      else
	continue;
    }
    if (!check_talloc(env_len))
      return -1;
    env_e_la = talloc(env_len);
    dosmemput(ep, env_len, env_e_la);
  }

  /* If no !proxy variable was found, create one.  */
  if (proxy && !seen_proxy)
  {
    if (!check_talloc(proxy_len))
      return -1;
    env_e_la = talloc(proxy_len);
    dosmemput(proxy, proxy_len, env_e_la);
  }

  /* Terminate by an extra NULL char.  */
  arg_header[0] = 0;

  /* The name of the program that owns the environment.  */
  arg_header[1] = 1;	/* the number of strings (1, little-endian) */
  arg_header[2] = 0;
  if (!check_talloc(3 + proglen))
    return -1;
  dosmemput(arg_header, 3, talloc(3));
  env_e_la = talloc(proglen);
  dosmemput(progname, proglen, env_e_la);

  /* Prepare the parameter block and call Int 21h/AX=4B00h.  */
#if 0
  arg_la  += tbuf_beg;
  env_la  += tbuf_beg;
  fcb1_la += tbuf_beg;
  fcb2_la += tbuf_beg;
  parm_la += tbuf_beg;
  program_la += tbuf_beg;
#endif
  parm.eseg     = env_la / 16;
  parm.argseg	= arg_la / 16;
  parm.argoff	= arg_la & 15;
  parm.fcb1_seg = fcb1_la / 16;
  parm.fcb1_off = fcb1_la & 15;
  parm.fcb2_seg = fcb2_la / 16;
  parm.fcb2_off = fcb2_la & 15;
  dosmemput(&parm, sizeof(parm), parm_la);

  r.x.ax = 0x4b00;
  r.x.ds = program_la / 16;
  r.x.dx = program_la & 15;
  r.x.es = parm_la / 16;
  r.x.bx = parm_la & 15;
  __dpmi_int(0x21, &r);
#if 0
  if (tbuf_selector)
    __dpmi_free_dos_memory (tbuf_selector);
  tbuf_selector = 0;
#endif
  if (r.x.flags & 1)
  {
    errno = __doserr_to_errno(r.x.ax);
    return -1;
  }
  
  r.h.ah = 0x4d;
  __dpmi_int(0x21, &r);
  
  if (r.x.flags & 1)
  {
    errno = __doserr_to_errno(r.x.ax);
    return -1;
  }

  /* AH holds the ``system exit code'' which is non-zero if the
     child was aborted by Ctrl-C, or Critical Device error (also
     if the child installs itself as a TSR).  */
  if (r.h.ah && r.h.ah != 3) /* 3 means it exited as TSR (is it ``normal''?) */
    {
      errno = EINTR;	/* what else can we put in `errno'? */
      return ( ((r.h.ah == 1 ? SIGINT : SIGABRT) << 8) | r.h.al );
    }
  return r.h.al;	/* AL holds the child exit code */
}

int
_dos_exec(const char *program, const char *args, char * const envp[])
{
  tbuf_beg = tbuf_ptr = __tb;
  tbuf_len = _go32_info_block.size_of_transfer_buffer;
  tbuf_end = tbuf_beg + tbuf_len - 1;
  return direct_exec_tail(program, args, envp, 0, 2);
}

static char GO32_V2_STRING[] = "go32-v2.exe";
static char GO32_STRING[]    = "go32.exe";

/* A list of known shells which require we DON'T quote command
   lines that are passed to them with the /c or -c switch.  */
static const char *shell_brokets[] = {