newlib/winsup/cygwin/spawn.cc

/* spawn.cc

   Copyright 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,
   2007, 2008, 2009, 2010, 2011, 2012, 2013 Red Hat, Inc.

This file is part of Cygwin.

This software is a copyrighted work licensed under the terms of the
Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
details. */

#include "winsup.h"
#include <stdlib.h>
#include <unistd.h>
#include <process.h>
#include <sys/wait.h>
#include <wingdi.h>
#include <winuser.h>
#include <wchar.h>
#include <ctype.h>
#include <sys/cygwin.h>
#include "cygerrno.h"
#include "security.h"
#include "sigproc.h"
#include "pinfo.h"
#include "path.h"
#include "fhandler.h"
#include "dtable.h"
#include "cygheap.h"
#include "child_info.h"
#include "environ.h"
#include "cygtls.h"
#include "tls_pbuf.h"
#include "winf.h"
#include "ntdll.h"

static const suffix_info exe_suffixes[] =
{
  suffix_info ("", 1),
  suffix_info (".exe", 1),
  suffix_info (".com"),
  suffix_info (NULL)
};

/* Add .exe to PROG if not already present and see if that exists.
   If not, return PROG (converted from posix to win32 rules if necessary).
   The result is always BUF.

   Returns (possibly NULL) suffix */

static const char *
perhaps_suffix (const char *prog, path_conv& buf, int& err, unsigned opt)
{
  const char *ext;

  err = 0;
  debug_printf ("prog '%s'", prog);
  buf.check (prog, PC_SYM_FOLLOW | PC_NULLEMPTY,
	     (opt & FE_DLL) ? stat_suffixes : exe_suffixes);

  if (buf.isdir ())
    {
      err = EACCES;
      ext = NULL;
    }
  else if (!buf.exists ())
    {
      err = ENOENT;
      ext = NULL;
    }
  else if (buf.known_suffix)
    ext = buf.get_win32 () + (buf.known_suffix - buf.get_win32 ());
  else
    ext = strchr (buf.get_win32 (), '\0');

  debug_printf ("buf %s, suffix found '%s'", (char *) buf.get_win32 (), ext);
  return ext;
}

/* Find an executable name, possibly by appending known executable
   suffixes to it.  The win32-translated name is placed in 'buf'.
   Any found suffix is returned in known_suffix.

   If the file is not found and !null_if_not_found then the win32 version
   of name is placed in buf and returned.  Otherwise the contents of buf
   is undefined and NULL is returned.  */

const char * __reg3
find_exec (const char *name, path_conv& buf, const char *mywinenv,
	   unsigned opt, const char **known_suffix)
{
  const char *suffix = "";
  debug_printf ("find_exec (%s)", name);
  const char *retval;
  tmp_pathbuf tp;
  char *tmp = tp.c_get ();
  const char *posix = (opt & FE_NATIVE) ? NULL : name;
  bool has_slash = !!strpbrk (name, "/\\");
  int err;

  /* Check to see if file can be opened as is first.
     Win32 systems always check . first, but PATH may not be set up to
     do this. */
  if ((has_slash || opt & FE_CWD)
      && (suffix = perhaps_suffix (name, buf, err, opt)) != NULL)
    {
      if (posix && !has_slash)
	{
	  tmp[0] = '.';
	  tmp[1] = '/';
	  strcpy (tmp + 2, name);
	  posix = tmp;
	}
      retval = buf.get_win32 ();
      goto out;
    }

  win_env *winpath;
  const char *path;
  const char *posix_path;

  posix = (opt & FE_NATIVE) ? NULL : tmp;

  if (strchr (mywinenv, '/'))
    {
      /* it's not really an environment variable at all */
      int n = cygwin_conv_path_list (CCP_POSIX_TO_WIN_A, mywinenv, NULL, 0);
      char *s = (char *) alloca (n);
      if (cygwin_conv_path_list (CCP_POSIX_TO_WIN_A, mywinenv, s, n))
	goto errout;
      path = s;
      posix_path = mywinenv - 1;
    }
  else if (has_slash || strchr (name, '\\') || isdrive (name)
      || !(winpath = getwinenv (mywinenv))
      || !(path = winpath->get_native ()) || *path == '\0')
    /* Return the error condition if this is an absolute path or if there
       is no PATH to search. */
    goto errout;
  else
    posix_path = winpath->get_posix () - 1;

  debug_printf ("%s%s", mywinenv, path);
  /* Iterate over the specified path, looking for the file with and without
     executable extensions. */
  do
    {
      posix_path++;
      char *eotmp = strccpy (tmp, &path, ';');
      /* An empty path or '.' means the current directory, but we've
	 already tried that.  */
      if (opt & FE_CWD && (tmp[0] == '\0' || (tmp[0] == '.' && tmp[1] == '\0')))
	continue;

      *eotmp++ = '\\';
      strcpy (eotmp, name);

      debug_printf ("trying %s", tmp);

      int err1;

      if ((suffix = perhaps_suffix (tmp, buf, err1, opt)) != NULL)
	{
	  if (buf.has_acls () && check_file_access (buf, X_OK, true))
	    continue;

	  if (posix == tmp)
	    {
	      eotmp = strccpy (tmp, &posix_path, ':');
	      if (eotmp == tmp)
		*eotmp++ = '.';
	      *eotmp++ = '/';
	      strcpy (eotmp, name);
	    }
	  retval = buf.get_win32 ();
	  goto out;
	}
    }
  while (*path && *++path && (posix_path = strchr (posix_path, ':')));

 errout:
  posix = NULL;
  /* Couldn't find anything in the given path.
     Take the appropriate action based on null_if_not_found. */
  if (opt & FE_NNF)
    retval = NULL;
  else if (!(opt & FE_NATIVE))
    retval = name;
  else
    {
      buf.check (name);
      retval = buf.get_win32 ();
    }

 out:
  if (posix)
    retval = buf.set_path (posix);
  debug_printf ("%s = find_exec (%s)", (char *) buf.get_win32 (), name);
  if (known_suffix)
    *known_suffix = suffix ?: strchr (buf.get_win32 (), '\0');
  if (!retval && err)
    set_errno (err);
  return retval;
}

/* Utility for child_info_spawn::worker.  */

static HANDLE
handle (int fd, bool writing)
{
  HANDLE h;
  cygheap_fdget cfd (fd);

  if (cfd < 0)
    h = INVALID_HANDLE_VALUE;
  else if (cfd->close_on_exec ())
    h = INVALID_HANDLE_VALUE;
  else if (!writing)
    h = cfd->get_handle ();
  else
    h = cfd->get_output_handle ();

  return h;
}

int
iscmd (const char *argv0, const char *what)
{
  int n;
  n = strlen (argv0) - strlen (what);
  if (n >= 2 && argv0[1] != ':')
    return 0;
  return n >= 0 && strcasematch (argv0 + n, what) &&
	 (n == 0 || isdirsep (argv0[n - 1]));
}

#define ILLEGAL_SIG_FUNC_PTR ((_sig_func_ptr) (-2))
struct system_call_handle
{
  _sig_func_ptr oldint;
  _sig_func_ptr oldquit;
  sigset_t oldmask;
  bool is_system_call ()
  {
    return oldint != ILLEGAL_SIG_FUNC_PTR;
  }
  system_call_handle (bool issystem)
  {
    if (!issystem)
      oldint = ILLEGAL_SIG_FUNC_PTR;
    else
      {
	sig_send (NULL, __SIGHOLD);
	oldint = NULL;
      }
  }
  void arm()
  {
    if (is_system_call ())
      {
	sigset_t child_block;
	oldint = signal (SIGINT,  SIG_IGN);
	oldquit = signal (SIGQUIT, SIG_IGN);
	sigemptyset (&child_block);
	sigaddset (&child_block, SIGCHLD);
	sigprocmask (SIG_BLOCK, &child_block, &oldmask);
	sig_send (NULL, __SIGNOHOLD);
      }
  }
  ~system_call_handle ()
  {
    if (is_system_call ())
      {
	signal (SIGINT, oldint);
	signal (SIGQUIT, oldquit);
	sigprocmask (SIG_SETMASK, &oldmask, NULL);
      }
  }
# undef cleanup
};

child_info_spawn NO_COPY ch_spawn;

int
child_info_spawn::worker (const char *prog_arg, const char *const *argv,
			  const char *const envp[], int mode,
			  int in__stdin, int in__stdout)
{
  bool rc;
  pid_t cygpid;
  int res = -1;

  /* Check if we have been called from exec{lv}p or spawn{lv}p and mask
     mode to keep only the spawn mode. */
  bool p_type_exec = !!(mode & _P_PATH_TYPE_EXEC);
  mode = _P_MODE (mode);

  if (prog_arg == NULL)
    {
      syscall_printf ("prog_arg is NULL");
      set_errno (EFAULT);	/* As on Linux. */
      return -1;
    }
  if (!prog_arg[0])
    {
      syscall_printf ("prog_arg is empty");
      set_errno (ENOENT);	/* Per POSIX */
      return -1;
    }

  syscall_printf ("mode = %d, prog_arg = %.9500s", mode, prog_arg);

  /* FIXME: This is no error condition on Linux. */
  if (argv == NULL)
    {
      syscall_printf ("argv is NULL");
      set_errno (EINVAL);
      return -1;
    }

  av newargv;
  linebuf cmd;
  PWCHAR envblock = NULL;
  path_conv real_path;
  bool reset_sendsig = false;

  tmp_pathbuf tp;
  PWCHAR runpath = tp.w_get ();
  int c_flags;

  bool null_app_name = false;
  STARTUPINFOW si = {};
  int looped = 0;

  myfault efault;
  system_call_handle system_call (mode == _P_SYSTEM);
  if (efault.faulted ())
    {
      if (get_errno () == ENOMEM)
	set_errno (E2BIG);
      else
	set_errno (EFAULT);
      res = -1;
      goto out;
    }

  child_info_types chtype;
  if (mode == _P_OVERLAY)
    chtype = _CH_EXEC;
  else
    chtype = _CH_SPAWN;

  moreinfo = cygheap_exec_info::alloc ();

  /* CreateProcess takes one long string that is the command line (sigh).
     We need to quote any argument that has whitespace or embedded "'s.  */

  int ac;
  for (ac = 0; argv[ac]; ac++)
    /* nothing */;

  int err;
  const char *ext;
  if ((ext = perhaps_suffix (prog_arg, real_path, err, FE_NADA)) == NULL)
    {
      set_errno (err);
      res = -1;
      goto out;
    }

  res = newargv.setup (prog_arg, real_path, ext, ac, argv, p_type_exec);

  if (res)
    goto out;

  if (!real_path.iscygexec () && ::cygheap->cwd.get_error ())
    {
      small_printf ("Error: Current working directory %s.\n"
		    "Can't start native Windows application from here.\n\n",
		    ::cygheap->cwd.get_error_desc ());
      set_errno (::cygheap->cwd.get_error ());
      res = -1;
      goto out;
    }

  if (ac == 3 && argv[1][0] == '/' && tolower (argv[1][1]) == 'c' &&
      (iscmd (argv[0], "command.com") || iscmd (argv[0], "cmd.exe")))
    {
      real_path.check (prog_arg);
      cmd.add ("\"");
      if (!real_path.error)
	cmd.add (real_path.get_win32 ());
      else
	cmd.add (argv[0]);
      cmd.add ("\"");
      cmd.add (" ");
      cmd.add (argv[1]);
      cmd.add (" ");
      cmd.add (argv[2]);
      real_path.set_path (argv[0]);
      null_app_name = true;
    }
  else
    {
      if (real_path.iscygexec ())
	{
	  moreinfo->argc = newargv.argc;
	  moreinfo->argv = newargv;
	}
      if ((wincmdln || !real_path.iscygexec ())
	   && !cmd.fromargv (newargv, real_path.get_win32 (),
			     real_path.iscygexec ()))
	{
	  res = -1;
	  goto out;
	}


      if (mode != _P_OVERLAY || !real_path.iscygexec ()
	  || !DuplicateHandle (GetCurrentProcess (), myself.shared_handle (),
			       GetCurrentProcess (), &moreinfo->myself_pinfo,
			       0, TRUE, DUPLICATE_SAME_ACCESS))
	moreinfo->myself_pinfo = NULL;
      else
	VerifyHandle (moreinfo->myself_pinfo);
    }

  PROCESS_INFORMATION pi;
  pi.hProcess = pi.hThread = NULL;
  pi.dwProcessId = pi.dwThreadId = 0;

  /* Set up needed handles for stdio */
  si.dwFlags = STARTF_USESTDHANDLES;
  si.hStdInput = handle ((in__stdin < 0 ? 0 : in__stdin), false);
  si.hStdOutput = handle ((in__stdout < 0 ? 1 : in__stdout), true);
  si.hStdError = handle (2, true);

  si.cb = sizeof (si);

  c_flags = GetPriorityClass (GetCurrentProcess ());
  sigproc_printf ("priority class %d", c_flags);

  c_flags |= CREATE_SEPARATE_WOW_VDM | CREATE_UNICODE_ENVIRONMENT;

  if (wincap.has_program_compatibility_assistant ())
    {
      /* We're adding the CREATE_BREAKAWAY_FROM_JOB flag here to workaround
	 issues with the "Program Compatibility Assistant (PCA) Service"
	 starting with Windows Vista.  For some reason, when starting long
	 running sessions from mintty(*), the affected svchost.exe process
	 takes more and more memory and at one point takes over the CPU.  At
	 this point the machine becomes unresponsive.  The only way to get
	 back to normal is to stop the entire mintty session, or to stop the
	 PCA service.  However, a process which is controlled by PCA is part
	 of a compatibility job, which allows child processes to break away
	 from the job.  This helps to avoid this issue.

	 First we call IsProcessInJob.  It fetches the information whether or
	 not we're part of a job 20 times faster than QueryInformationJobObject.

	 (*) Note that this is not mintty's fault.  It has just been observed
	 with mintty in the first place.  See the archives for more info:
	 http://cygwin.com/ml/cygwin-developers/2012-02/msg00018.html */

      JOBOBJECT_BASIC_LIMIT_INFORMATION jobinfo;
      BOOL is_in_job;

      if (IsProcessInJob (GetCurrentProcess (), NULL, &is_in_job)
	  && is_in_job
	  && QueryInformationJobObject (NULL, JobObjectBasicLimitInformation,
				     &jobinfo, sizeof jobinfo, NULL)
	  && (jobinfo.LimitFlags & (JOB_OBJECT_LIMIT_BREAKAWAY_OK
				    | JOB_OBJECT_LIMIT_SILENT_BREAKAWAY_OK)))
	{
	  debug_printf ("Add CREATE_BREAKAWAY_FROM_JOB");
	  c_flags |= CREATE_BREAKAWAY_FROM_JOB;
	}
    }

  if (mode == _P_DETACH)
    c_flags |= DETACHED_PROCESS;
  else
    fhandler_console::need_invisible ();

  if (mode != _P_OVERLAY)
    myself->exec_sendsig = NULL;
  else
    {
      /* Reset sendsig so that any process which wants to send a signal
	 to this pid will wait for the new process to become active.
	 Save the old value in case the exec fails.  */
      if (!myself->exec_sendsig)
	{
	  myself->exec_sendsig = myself->sendsig;
	  myself->exec_dwProcessId = myself->dwProcessId;
	  myself->sendsig = NULL;
	  reset_sendsig = true;
	}
    }

  if (null_app_name)
    runpath = NULL;
  else
    {
      USHORT len = real_path.get_nt_native_path ()->Length / sizeof (WCHAR);
      if (RtlEqualUnicodePathPrefix (real_path.get_nt_native_path (),
				     &ro_u_natp, FALSE))
	{
	  runpath = real_path.get_wide_win32_path (runpath);
	  /* If the executable path length is < MAX_PATH, make sure the long
	     path win32 prefix is removed from the path to make subsequent
	     not long path aware native Win32 child processes happy. */
	  if (len < MAX_PATH + 4)
	    {
	      if (runpath[5] == ':')
		runpath += 4;
	      else if (len < MAX_PATH + 6)
		*(runpath += 6) = L'\\';
	    }
	}
      else if (len < NT_MAX_PATH - ro_u_globalroot.Length / sizeof (WCHAR))
	{
	  UNICODE_STRING rpath;

	  RtlInitEmptyUnicodeString (&rpath, runpath,
				     (NT_MAX_PATH - 1) * sizeof (WCHAR));
	  RtlCopyUnicodeString (&rpath, &ro_u_globalroot);
	  RtlAppendUnicodeStringToString (&rpath,
					  real_path.get_nt_native_path ());
	}
      else
	{
	  set_errno (ENAMETOOLONG);
	  res = -1;
	  goto out;
	}
    }

  cygbench ("spawn-worker");

  if (!real_path.iscygexec())
    ::cygheap->fdtab.set_file_pointers_for_exec ();

  moreinfo->envp = build_env (envp, envblock, moreinfo->envc,
			      real_path.iscygexec ());
  if (!moreinfo->envp || !envblock)
    {
      set_errno (E2BIG);
      res = -1;
      goto out;
    }
  set (chtype, real_path.iscygexec ());
  __stdin = in__stdin;
  __stdout = in__stdout;
  record_children ();

  si.lpReserved2 = (LPBYTE) this;
  si.cbReserved2 = sizeof (*this);

  /* Depends on set call above.
     Some file types might need extra effort in the parent after CreateProcess
     and before copying the datastructures to the child.  So we have to start
     the child in suspend state, unfortunately, to avoid a race condition. */
  if (!newargv.win16_exe
      && (!iscygwin () || mode != _P_OVERLAY
	  || ::cygheap->fdtab.need_fixup_before ()))
    c_flags |= CREATE_SUSPENDED;
  /* If a native application should be spawned, we test here if the spawning
     process is running in a console and, if so, if it's a foreground or
     background process.  If it's a background process, we start the native
     process with the CREATE_NEW_PROCESS_GROUP flag set.  This lets the native
     process ignore Ctrl-C by default.  If we don't do that, pressing Ctrl-C
     in a console will break native processes running in the background,
     because the Ctrl-C event is sent to all processes in the console, unless
     they ignore it explicitely.  CREATE_NEW_PROCESS_GROUP does that for us. */
  if (!iscygwin () && fhandler_console::exists ()
      && fhandler_console::tc_getpgid () != myself->pgid)
    c_flags |= CREATE_NEW_PROCESS_GROUP;
  refresh_cygheap ();

  if (mode == _P_DETACH)
    /* all set */;
  else if (mode != _P_OVERLAY || !my_wr_proc_pipe)
    prefork ();
  else
    wr_proc_pipe = my_wr_proc_pipe;

  /* Don't allow child to inherit these handles if it's not a Cygwin program.
     wr_proc_pipe will be injected later.  parent won't be used by the child
     so there is no reason for the child to have it open as it can confuse
     ps into thinking that children of windows processes are all part of
     the same "execed" process.
     FIXME: Someday, make it so that parent is never created when starting
     non-Cygwin processes. */
  if (!iscygwin ())
    {
      SetHandleInformation (wr_proc_pipe, HANDLE_FLAG_INHERIT, 0);
      SetHandleInformation (parent, HANDLE_FLAG_INHERIT, 0);
    }
  /* FIXME: racy */
  if (mode != _P_OVERLAY)
    SetHandleInformation (my_wr_proc_pipe, HANDLE_FLAG_INHERIT, 0);
  parent_winpid = GetCurrentProcessId ();

loop:
  /* When ruid != euid we create the new process under the current original
     account and impersonate in child, this way maintaining the different
     effective vs. real ids.
     FIXME: If ruid != euid and ruid != saved_uid we currently give
     up on ruid. The new process will have ruid == euid. */
  ::cygheap->user.deimpersonate ();

  if (!real_path.iscygexec () && mode == _P_OVERLAY)
    myself->process_state |= PID_NOTCYGWIN;

  wchar_t wcmd[(size_t) cmd];
  if (!::cygheap->user.issetuid ()
      || (::cygheap->user.saved_uid == ::cygheap->user.real_uid
	  && ::cygheap->user.saved_gid == ::cygheap->user.real_gid
	  && !::cygheap->user.groups.issetgroups ()
	  && !::cygheap->user.setuid_to_restricted))
    {
      rc = CreateProcessW (runpath,	  /* image name - with full path */
			   cmd.wcs (wcmd),/* what was passed to exec */
			   &sec_none_nih, /* process security attrs */
			   &sec_none_nih, /* thread security attrs */
			   TRUE,	  /* inherit handles from parent */
			   c_flags,
			   envblock,	  /* environment */
			   NULL,
			   &si,
			   &pi);
    }
  else
    {
      /* Give access to myself */
      if (mode == _P_OVERLAY)
	myself.set_acl();

      WCHAR wstname[1024] = { L'\0' };
      HWINSTA hwst_orig = NULL, hwst = NULL;
      HDESK hdsk_orig = NULL, hdsk = NULL;
      PSECURITY_ATTRIBUTES sa;
      DWORD n;

      hwst_orig = GetProcessWindowStation ();
      hdsk_orig = GetThreadDesktop (GetCurrentThreadId ());
      GetUserObjectInformationW (hwst_orig, UOI_NAME, wstname, 1024, &n);
      /* Prior to Vista it was possible to start a service with the
	 "Interact with desktop" flag.  This started the service in the
	 interactive window station of the console.  A big security
	 risk, but we don't want to disable this behaviour for older
	 OSes because it's still heavily used by some users.  They have
	 been warned. */
      if (!::cygheap->user.setuid_to_restricted
	  && wcscasecmp (wstname, L"WinSta0") != 0)
	{
	  WCHAR sid[128];

	  sa = sec_user ((PSECURITY_ATTRIBUTES) alloca (1024),
			 ::cygheap->user.sid ());
	  /* We're creating a window station per user, not per logon session.
	     First of all we might not have a valid logon session for
	     the user (logon by create_token), and second, it doesn't
	     make sense in terms of security to create a new window
	     station for every logon of the same user.  It just fills up
	     the system with window stations for no good reason. */
	  hwst = CreateWindowStationW (::cygheap->user.get_windows_id (sid), 0,
				       GENERIC_READ | GENERIC_WRITE, sa);
	  if (!hwst)
	    system_printf ("CreateWindowStation failed, %E");
	  else if (!SetProcessWindowStation (hwst))
	    system_printf ("SetProcessWindowStation failed, %E");
	  else if (!(hdsk = CreateDesktopW (L"Default", NULL, NULL, 0,
					    GENERIC_ALL, sa)))
	    system_printf ("CreateDesktop failed, %E");
	  else
	    {
	      wcpcpy (wcpcpy (wstname, sid), L"\\Default");
	      si.lpDesktop = wstname;
	      debug_printf ("Desktop: %W", si.lpDesktop);
	    }
	}

      rc = CreateProcessAsUserW (::cygheap->user.primary_token (),
			   runpath,	  /* image name - with full path */
			   cmd.wcs (wcmd),/* what was passed to exec */
			   &sec_none_nih, /* process security attrs */
			   &sec_none_nih, /* thread security attrs */
			   TRUE,	  /* inherit handles from parent */
			   c_flags,
			   envblock,	  /* environment */
			   NULL,
			   &si,
			   &pi);
      if (hwst)
	{
	  SetProcessWindowStation (hwst_orig);
	  CloseWindowStation (hwst);
	}
      if (hdsk)
	{
	  SetThreadDesktop (hdsk_orig);
	  CloseDesktop (hdsk);
	}
    }

  if (mode != _P_OVERLAY)
    SetHandleInformation (my_wr_proc_pipe, HANDLE_FLAG_INHERIT,
			  HANDLE_FLAG_INHERIT);

  /* Set errno now so that debugging messages from it appear before our
     final debugging message [this is a general rule for debugging
     messages].  */
  if (!rc)
    {
      __seterrno ();
      syscall_printf ("CreateProcess failed, %E");
      /* If this was a failed exec, restore the saved sendsig. */
      if (reset_sendsig)
	{
	  myself->sendsig = myself->exec_sendsig;
	  myself->exec_sendsig = NULL;
	}
      myself->process_state &= ~PID_NOTCYGWIN;
      /* Reset handle inheritance to default when the execution of a non-Cygwin
	 process fails.  Only need to do this for _P_OVERLAY since the handle will
	 be closed otherwise.  Don't need to do this for 'parent' since it will
	 be closed in every case.  See FIXME above. */
      if (!iscygwin () && mode == _P_OVERLAY)
	SetHandleInformation (wr_proc_pipe, HANDLE_FLAG_INHERIT,
			      HANDLE_FLAG_INHERIT);
      if (wr_proc_pipe == my_wr_proc_pipe)
	wr_proc_pipe = NULL;	/* We still own it: don't nuke in destructor */

      /* Restore impersonation. In case of _P_OVERLAY this isn't
	 allowed since it would overwrite child data. */
      if (mode != _P_OVERLAY)
	::cygheap->user.reimpersonate ();

      res = -1;
      goto out;
    }

  /* The CREATE_SUSPENDED case is handled below */
  if (iscygwin () && !(c_flags & CREATE_SUSPENDED))
    strace.write_childpid (pi.dwProcessId);

  /* Fixup the parent data structures if needed and resume the child's
     main thread. */
  if (::cygheap->fdtab.need_fixup_before ())
    ::cygheap->fdtab.fixup_before_exec (pi.dwProcessId);

  if (mode != _P_OVERLAY)
    cygpid = cygwin_pid (pi.dwProcessId);
  else
    cygpid = myself->pid;

  /* We print the original program name here so the user can see that too.  */
  syscall_printf ("pid %d, prog_arg %s, cmd line %.9500s)",
		  rc ? cygpid : (unsigned int) -1, prog_arg, (const char *) cmd);

  /* Name the handle similarly to proc_subproc. */
  ProtectHandle1 (pi.hProcess, childhProc);

  if (mode == _P_OVERLAY)
    {
      myself->dwProcessId = pi.dwProcessId;
      strace.execing = 1;
      myself.hProcess = hExeced = pi.hProcess;
      real_path.get_wide_win32_path (myself->progname); // FIXME: race?
      sigproc_printf ("new process name %W", myself->progname);
      if (!iscygwin ())
	close_all_files ();
    }
  else
    {
      myself->set_has_pgid_children ();
      ProtectHandle (pi.hThread);
      pinfo child (cygpid,
		   PID_IN_USE | (real_path.iscygexec () ? 0 : PID_NOTCYGWIN));
      if (!child)
	{
	  syscall_printf ("pinfo failed");
	  if (get_errno () != ENOMEM)
	    set_errno (EAGAIN);
	  res = -1;
	  goto out;
	}
      child->dwProcessId = pi.dwProcessId;
      child.hProcess = pi.hProcess;

      real_path.get_wide_win32_path (child->progname);
      /* FIXME: This introduces an unreferenced, open handle into the child.
	 The purpose is to keep the pid shared memory open so that all of
	 the fields filled out by child.remember do not disappear and so there
	 is not a brief period during which the pid is not available.
	 However, we should try to find another way to do this eventually. */
      DuplicateHandle (GetCurrentProcess (), child.shared_handle (),
		       pi.hProcess, NULL, 0, 0, DUPLICATE_SAME_ACCESS);
      child->start_time = time (NULL); /* Register child's starting time. */
      child->nice = myself->nice;
      postfork (child);
      if (!child.remember (mode == _P_DETACH))
	{
	  /* FIXME: Child in strange state now */
	  CloseHandle (pi.hProcess);
	  ForceCloseHandle (pi.hThread);
	  res = -1;
	  goto out;
	}
    }

  /* Start the child running */
  if (c_flags & CREATE_SUSPENDED)
    {
      /* Inject a non-inheritable wr_proc_pipe handle into child so that we
	 can accurately track when the child exits without keeping this
	 process waiting around for it to exit.  */
      if (!iscygwin ())
	DuplicateHandle (GetCurrentProcess (), wr_proc_pipe, pi.hProcess, NULL,
			 0, false, DUPLICATE_SAME_ACCESS);
      ResumeThread (pi.hThread);
      if (iscygwin ())
	strace.write_childpid (pi.dwProcessId);
    }
  ForceCloseHandle (pi.hThread);

  sigproc_printf ("spawned windows pid %d", pi.dwProcessId);

  bool synced;
  if ((mode == _P_DETACH || mode == _P_NOWAIT) && !iscygwin ())
    synced = false;
  else
    /* Just mark a non-cygwin process as 'synced'.  We will still eventually
       wait for it to exit in maybe_set_exit_code_from_windows(). */
    synced = iscygwin () ? sync (pi.dwProcessId, pi.hProcess, INFINITE) : true;

  switch (mode)
    {
    case _P_OVERLAY:
      myself.hProcess = pi.hProcess;
      if (!synced)
	{
	  if (!proc_retry (pi.hProcess))
	    {
	      looped++;
	      goto loop;
	    }
	  close_all_files (true);
	}
      else
	{
	  if (iscygwin ())
	    close_all_files (true);
	  if (!my_wr_proc_pipe
	      && WaitForSingleObject (pi.hProcess, 0) == WAIT_TIMEOUT)
	    wait_for_myself ();
	}
      myself.exit (EXITCODE_NOSET);
      break;
    case _P_WAIT:
    case _P_SYSTEM:
      system_call.arm ();
      if (waitpid (cygpid, &res, 0) != cygpid)
	res = -1;
      break;
    case _P_DETACH:
      res = 0;	/* Lost all memory of this child. */
      break;
    case _P_NOWAIT:
    case _P_NOWAITO:
    case _P_VFORK:
      res = cygpid;
      break;
    default:
      break;
    }

out:
  this->cleanup ();
  if (envblock)
    free (envblock);
  return (int) res;
}

extern "C" int
cwait (int *result, int pid, int)
{
  return waitpid (pid, result, 0);
}

/*
* Helper function for spawn runtime calls.
* Doesn't search the path.
*/

extern "C" int
spawnve (int mode, const char *path, const char *const *argv,
       const char *const *envp)
{
  static char *const empty_env[] = { NULL };

  int ret;
#ifdef NEWVFORK
  vfork_save *vf = vfork_storage.val ();

  if (vf != NULL && (vf->pid < 0) && mode == _P_OVERLAY)
    mode = _P_NOWAIT;
  else
    vf = NULL;
#endif

  syscall_printf ("spawnve (%s, %s, %p)", path, argv[0], envp);

  if (!envp)
    envp = empty_env;

  switch (_P_MODE (mode))
    {
    case _P_OVERLAY:
      ch_spawn.worker (path, argv, envp, mode);
      /* Errno should be set by worker.  */
      ret = -1;
      break;
    case _P_VFORK:
    case _P_NOWAIT:
    case _P_NOWAITO:
    case _P_WAIT:
    case _P_DETACH:
    case _P_SYSTEM:
      ret = ch_spawn.worker (path, argv, envp, mode);
#ifdef NEWVFORK
      if (vf)
	{
	  if (ret > 0)
	    {
	      debug_printf ("longjmping due to vfork");
	      vf->restore_pid (ret);
	    }
	}
#endif
      break;
    default:
      set_errno (EINVAL);
      ret = -1;
      break;
    }
  return ret;
}

/*
* spawn functions as implemented in the MS runtime library.
* Most of these based on (and copied from) newlib/libc/posix/execXX.c
*/

extern "C" int
spawnl (int mode, const char *path, const char *arg0, ...)
{
  int i;
  va_list args;
  const char *argv[256];

  va_start (args, arg0);
  argv[0] = arg0;
  i = 1;

  do
      argv[i] = va_arg (args, const char *);
  while (argv[i++] != NULL);

  va_end (args);

  return spawnve (mode, path, (char * const  *) argv, cur_environ ());
}

extern "C" int
spawnle (int mode, const char *path, const char *arg0, ...)
{
  int i;
  va_list args;
  const char * const *envp;
  const char *argv[256];

  va_start (args, arg0);
  argv[0] = arg0;
  i = 1;

  do
    argv[i] = va_arg (args, const char *);
  while (argv[i++] != NULL);

  envp = va_arg (args, const char * const *);
  va_end (args);

  return spawnve (mode, path, (char * const *) argv, (char * const *) envp);
}

extern "C" int
spawnlp (int mode, const char *file, const char *arg0, ...)
{
  int i;
  va_list args;
  const char *argv[256];
  path_conv buf;

  va_start (args, arg0);
  argv[0] = arg0;
  i = 1;

  do
      argv[i] = va_arg (args, const char *);
  while (argv[i++] != NULL);

  va_end (args);

  return spawnve (mode | _P_PATH_TYPE_EXEC, find_exec (file, buf),
		  (char * const *) argv, cur_environ ());
}

extern "C" int
spawnlpe (int mode, const char *file, const char *arg0, ...)
{
  int i;
  va_list args;
  const char * const *envp;
  const char *argv[256];
  path_conv buf;

  va_start (args, arg0);
  argv[0] = arg0;
  i = 1;

  do
    argv[i] = va_arg (args, const char *);
  while (argv[i++] != NULL);

  envp = va_arg (args, const char * const *);
  va_end (args);

  return spawnve (mode | _P_PATH_TYPE_EXEC, find_exec (file, buf),
		  (char * const *) argv, envp);
}

extern "C" int
spawnv (int mode, const char *path, const char * const *argv)
{
  return spawnve (mode, path, argv, cur_environ ());
}

extern "C" int
spawnvp (int mode, const char *file, const char * const *argv)
{
  path_conv buf;
  return spawnve (mode | _P_PATH_TYPE_EXEC, find_exec (file, buf), argv,
		  cur_environ ());
}

extern "C" int
spawnvpe (int mode, const char *file, const char * const *argv,
	  const char * const *envp)
{
  path_conv buf;
  return spawnve (mode | _P_PATH_TYPE_EXEC, find_exec (file, buf), argv, envp);
}

int
av::setup (const char *prog_arg, path_conv& real_path, const char *ext,
	   int argc, const char *const *argv, bool p_type_exec)
{
  const char *p;
  bool exeext = ascii_strcasematch (ext, ".exe");
  new (this) av (argc, argv);
  if ((exeext && real_path.iscygexec ()) || ascii_strcasematch (ext, ".bat")
      || (!*ext && ((p = ext - 4) > real_path.get_win32 ())
	  && (ascii_strcasematch (p, ".bat") || ascii_strcasematch (p, ".cmd")
	      || ascii_strcasematch (p, ".btm"))))
    /* no extra checks needed */;
  else
    while (1)
      {
	char *pgm = NULL;
	char *arg1 = NULL;
	char *ptr, *buf;
	OBJECT_ATTRIBUTES attr;
	IO_STATUS_BLOCK io;
	HANDLE h;
	NTSTATUS status;
	LARGE_INTEGER size;

	status = NtOpenFile (&h, SYNCHRONIZE | GENERIC_READ,
			     real_path.get_object_attr (attr, sec_none_nih),
			     &io, FILE_SHARE_VALID_FLAGS,
			     FILE_SYNCHRONOUS_IO_NONALERT
			     | FILE_OPEN_FOR_BACKUP_INTENT
			     | FILE_NON_DIRECTORY_FILE);
	if (!NT_SUCCESS (status))
	  {
	    /* File is not readable?  Doesn't mean it's not executable.
	       Test for executability and if so, just assume the file is
	       a cygwin executable and go ahead. */
	    if (status == STATUS_ACCESS_DENIED && real_path.has_acls ()
		&& check_file_access (real_path, X_OK, true) == 0)
	      {
		real_path.set_cygexec (true);
		break;
	      }
	    goto err;
	  }
	if (!GetFileSizeEx (h, &size))
	  {
	    NtClose (h);
	    goto err;
	  }
	if (size.QuadPart > (LONGLONG) wincap.allocation_granularity ())
	  size.LowPart = wincap.allocation_granularity ();

	HANDLE hm = CreateFileMapping (h, &sec_none_nih, PAGE_READONLY,
				       0, 0, NULL);
	NtClose (h);
	if (!hm)
	  {
	    /* ERROR_FILE_INVALID indicates very likely an empty file. */
	    if (GetLastError () == ERROR_FILE_INVALID)
	      {
		debug_printf ("zero length file, treat as script.");
		goto just_shell;
	      }
	    goto err;
	  }
	/* Try to map the first 64K of the image.  That's enough for the local
	   tests, and it's enough for hook_or_detect_cygwin to compute the IAT
	   address. */
	buf = (char *) MapViewOfFile (hm, FILE_MAP_READ, 0, 0, size.LowPart);
	if (!buf)
	  {
	    CloseHandle (hm);
	    goto err;
	  }

	{
	  myfault efault;
	  if (efault.faulted ())
	    {
	      UnmapViewOfFile (buf);
	      CloseHandle (hm);
	      real_path.set_cygexec (false);
	      break;
	    }
	  if (buf[0] == 'M' && buf[1] == 'Z')
	    {
	      WORD subsys;
	      unsigned off = (unsigned char) buf[0x18] | (((unsigned char) buf[0x19]) << 8);
	      win16_exe = off < sizeof (IMAGE_DOS_HEADER);
	      if (!win16_exe)
		real_path.set_cygexec (hook_or_detect_cygwin (buf, NULL,
							      subsys, hm));
	      else
		real_path.set_cygexec (false);
	      UnmapViewOfFile (buf);
	      CloseHandle (hm);
	      break;
	    }
	}
	CloseHandle (hm);

	debug_printf ("%s is possibly a script", real_path.get_win32 ());

	ptr = buf;
	if (*ptr++ == '#' && *ptr++ == '!')
	  {
	    ptr += strspn (ptr, " \t");
	    size_t len = strcspn (ptr, "\r\n");
	    if (len)
	      {
		char *namebuf = (char *) alloca (len + 1);
		memcpy (namebuf, ptr, len);
		namebuf[len] = '\0';
		for (ptr = pgm = namebuf; *ptr; ptr++)
		  if (!arg1 && (*ptr == ' ' || *ptr == '\t'))
		    {
		      /* Null terminate the initial command and step over any
			 additional white space.  If we've hit the end of the
			 line, exit the loop.  Otherwise, we've found the first
			 argument. Position the current pointer on the last known
			 white space. */
		      *ptr = '\0';
		      char *newptr = ptr + 1;
		      newptr += strspn (newptr, " \t");
		      if (!*newptr)
			break;
		      arg1 = newptr;
		      ptr = newptr - 1;
		    }
	      }
	  }
	UnmapViewOfFile (buf);
  just_shell:
	if (!pgm)
	  {
	    if (!p_type_exec)
	      {
		/* Not called from exec[lv]p.  Don't try to treat as script. */
		debug_printf ("%s is not a valid executable",
			      real_path.get_win32 ());
		set_errno (ENOEXEC);
		return -1;
	      }
	    if (ascii_strcasematch (ext, ".com"))
	      break;
	    pgm = (char *) "/bin/sh";
	    arg1 = NULL;
	  }

	/* Check if script is executable.  Otherwise we start non-executable
	   scripts successfully, which is incorrect behaviour. */
	if (real_path.has_acls ()
	    && check_file_access (real_path, X_OK, true) < 0)
	  return -1;	/* errno is already set. */

	/* Replace argv[0] with the full path to the script if this is the
	   first time through the loop. */
	replace0_maybe (prog_arg);

	/* pointers:
	 * pgm	interpreter name
	 * arg1	optional string
	 */
	if (arg1)
	  unshift (arg1);

	/* FIXME: This should not be using FE_NATIVE.  It should be putting
	   the posix path on the argv list. */
	find_exec (pgm, real_path, "PATH=", FE_NATIVE, &ext);
	unshift (real_path.get_win32 (), 1);
      }
  if (real_path.iscygexec ())
    dup_all ();
  return 0;

err:
  __seterrno ();
  return -1;
}