/erts/emulator/sys/win32/sys.c

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/*
 * %CopyrightBegin%
 *
 * Copyright Ericsson AB 1996-2017. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * %CopyrightEnd%
 */
/*
 * system-dependent functions
 *
 */

#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif

#include "sys.h"
#include "erl_alloc.h"
#include "erl_sys_driver.h"
#include "global.h"
#include "erl_threads.h"
#include "../../drivers/win32/win_con.h"
#include "erl_cpu_topology.h"
#include <malloc.h>

void erts_sys_init_float(void);

void erl_start(int, char**);
void erts_exit(int n, char*, ...);
void erl_error(char*, va_list);

/*
 * Microsoft-specific function to map a WIN32 error code to a Posix errno.
 */
extern void _dosmaperr(DWORD);

#ifdef ERL_RUN_SHARED_LIB
#ifdef __argc
#undef __argc
#endif
#define __argc e_argc
#ifdef __argv
#undef __argv
#endif
#define __argv e_argv
#endif

typedef struct driver_data DriverData;

static void init_console();
static int get_and_remove_option(int* argc, char** argv, const char* option);
static char *get_and_remove_option2(int *argc, char **argv, 
				    const char *option);
static int init_async_io(DriverData *dp, struct async_io* aio, int use_threads);
static void release_async_io(struct async_io* aio, ErlDrvPort);
static void async_read_file(struct async_io* aio, LPVOID buf, DWORD numToRead);
static int async_write_file(struct async_io* aio, LPVOID buf, DWORD numToWrite);
static int get_overlapped_result(struct async_io* aio,
				 LPDWORD pBytesRead, BOOL wait);
static BOOL create_child_process(wchar_t *, HANDLE, HANDLE,
				 HANDLE, LPHANDLE, LPDWORD, BOOL,
				 LPVOID, wchar_t*, unsigned,
				 wchar_t **, int *);
static int create_pipe(LPHANDLE, LPHANDLE, BOOL, BOOL);
static int application_type(const wchar_t* originalName, wchar_t fullPath[MAX_PATH],
			   BOOL search_in_path, BOOL handle_quotes,
			   int *error_return);
static void *build_env_block(const erts_osenv_t *env);

HANDLE erts_service_event;

static erts_tsd_key_t win32_errstr_key;

static erts_atomic_t pipe_creation_counter;

/* Results from application_type(_w) is one of */
#define APPL_NONE 0
#define APPL_DOS  1
#define APPL_WIN3X 2
#define APPL_WIN32 3

static int driver_write(long, HANDLE, byte*, int);
static int create_file_thread(struct async_io* aio, int mode);
static void close_active_handle(DriverData *, HANDLE handle);
static DWORD WINAPI threaded_handle_closer(LPVOID param);
static DWORD WINAPI threaded_reader(LPVOID param);
static DWORD WINAPI threaded_writer(LPVOID param);
static DWORD WINAPI threaded_exiter(LPVOID param);

#ifdef DEBUG
static void debug_console(void);
#endif

BOOL WINAPI ctrl_handler(DWORD dwCtrlType);

#define PORT_BUFSIZ 4096

#define DRV_BUF_ALLOC(SZ) \
  erts_alloc_fnf(ERTS_ALC_T_DRV_DATA_BUF, (SZ))
#define DRV_BUF_REALLOC(P, SZ) \
  erts_realloc_fnf(ERTS_ALC_T_DRV_DATA_BUF, (P), (SZ))
#define DRV_BUF_FREE(P) \
  erts_free(ERTS_ALC_T_DRV_DATA_BUF, (P))

/********************* General functions ****************************/

/*
 * Whether create_pipe() should use a named pipe or an anonymous.
 * (Named pipes are not supported on Windows 95.)
 */

static int max_files = 1024;

static BOOL use_named_pipes;
static BOOL win_console = FALSE;


static OSVERSIONINFO int_os_version;	/* Version information for Win32. */

/*#define USE_CANCELIOEX
    Disabled the use of CancelIoEx as its been seen to cause problem with some
    drivers. Not sure what to blame; faulty drivers or some form of invalid use.
*/
#if defined(USE_CANCELIOEX)
static BOOL (WINAPI *fpCancelIoEx)(HANDLE,LPOVERLAPPED);
#endif

/* This is the system's main function (which may or may not be called "main")
   - do general system-dependent initialization
   - call erl_start() to parse arguments and do other init
*/

static erts_atomic_t sys_misc_mem_sz;

HMODULE beam_module = NULL;

void erl_sys_init();

void erl_sys_args(int* argc, char** argv);

int nohup;
#ifndef __GNUC__
void erts_sys_invalid_parameter_handler(const wchar_t * expression,
                                        const wchar_t * function, 
                                        const wchar_t * file, 
                                        unsigned int line,
                                        uintptr_t pReserved
                                        )
{
#ifdef DEBUG
    fprintf(stderr,
	    "Debug: Invalid parameter\"%ls\" "
	    "(detected in \"%ls\" [%ls:%d]) \n", 
	    (expression) ? expression : L"(unknown)",
	    (function) ? function : L"(unknown)",
	    (file) ? file : L"(unknown)",
	    line);
#endif
    return;
}
#endif

void sys_primitive_init(HMODULE beam)
{
#ifndef __GNUC__
    /* Initialize this module handle (the beam.dll module handle) and 
       take care of the standard library's aggressive invalid parameter 
       handling... */
    _set_invalid_parameter_handler(&erts_sys_invalid_parameter_handler);
#endif
    beam_module = (HMODULE) beam;
}

UWord
erts_sys_get_page_size(void)
{
    SYSTEM_INFO info;
    GetSystemInfo(&info);
    return (UWord)info.dwPageSize;
}

Uint
erts_sys_misc_mem_sz(void)
{
    Uint res = (Uint) erts_check_io_size();
    res += (Uint) erts_atomic_read_mb(&sys_misc_mem_sz);
    return res;
}

/*
 * Reset the terminal to the original settings on exit
 */
void sys_tty_reset(int exit_code)
{
    if (exit_code == ERTS_ERROR_EXIT)
	ConWaitForExit();
    else
	ConNormalExit();
}

void erl_sys_args(int* argc, char** argv)
{
    char *event_name;

    erts_sys_env_init();

    nohup = get_and_remove_option(argc, argv, "-nohup");

#ifdef DEBUG
    /*
     * Start a debug console if -console option given.
     */

    if (get_and_remove_option(argc, argv, "-console")) {
	debug_console();
    }
#endif

    if (nohup && (event_name = get_and_remove_option2(argc, argv, 
						      "-service_event"))) {
	if ((erts_service_event = 
	     OpenEvent(EVENT_ALL_ACCESS,FALSE,event_name)) == NULL) {
	    erts_fprintf(stderr,
			 "Warning: could not open service event: %s\r\n", 
			 event_name);
	}	    
    } else {
	erts_service_event = NULL;
    }

#ifdef DEBUG
    /*
     * Given the "-threads" option, always use threads instead of
     * named pipes.
     */

    if (get_and_remove_option(argc, argv, "-threads")) {
	use_named_pipes = FALSE;
    }
#endif
}

/*
 * Function returns 1 if we can read from all values in between
 * start and stop.
 */
int
erts_sys_is_area_readable(char *start, char *stop) {
    volatile char tmp;
    __try
    {
        while(start < stop) {
            tmp = *start;
            start++;
        }
    }
    __except(EXCEPTION_EXECUTE_HANDLER)
    {
        return 0;
    }
    return 1;
}

int erts_sys_prepare_crash_dump(int secs)
{
    Port *heart_port;
    Eterm heap[3];
    Eterm *hp = heap;
    Eterm list = NIL;

    heart_port = erts_get_heart_port();

    if (heart_port) {

	list = CONS(hp, make_small(8), list); hp += 2;

	/* send to heart port, CMD = 8, i.e. prepare crash dump =o */
	erts_port_output(NULL, ERTS_PORT_SIG_FLG_FORCE_IMM_CALL, heart_port,
			 heart_port->common.id, list, NULL);

	return 1;
    }

    /* Windows - free file descriptors are hopefully available */
    /* Alarm not used on windows */

    return 0;
}

int erts_set_signal(Eterm signal, Eterm type) {
    return 0;
}

static void
init_console(void)
{
    char* mode = erts_read_env("ERL_CONSOLE_MODE");

    if (!mode || strcmp(mode, "window") == 0) {
	win_console = TRUE;
	ConInit();
	/*nohup = 0;*/
    } else if (strncmp(mode, "tty:", 4) == 0) {
	if (mode[5] == 'c') {
	    setvbuf(stdout, NULL, _IONBF, 0);
	}
	if (mode[6] == 'c') {
	    setvbuf(stderr, NULL, _IONBF, 0);
	}
    }

    erts_free_read_env(mode);
}

int sys_max_files(void) 
{
    return max_files;
}

/*
 * Looks for the given option in the argv vector.  If it is found,
 * it will be removed from the argv vector.
 *
 * If the return value indicates that the option was found and removed,
 * it is the responsibility of the caller to decrement the value of argc.
 *
 * Returns: 0 if the option wasn't found, 1 if it was found
 */

static int
get_and_remove_option(int* argc, char* argv[], const char *option)
{
    int i;

    for (i = 1; i < *argc; i++) {
	if (strcmp(argv[i], option) == 0) {
	    (*argc)--;
	    while (i < *argc) {
		argv[i] = argv[i+1];
		i++;
	    }
	    argv[i] = NULL;
	    return 1;
	}
    }
    return 0;
}

static char *get_and_remove_option2(int *argc, char **argv, 
				    const char *option)
{
    char *ret;
    int i;

    for (i = 1; i < *argc; i++) {
	if (strcmp(argv[i], option) == 0) {
	    if (i+1 < *argc) {
		ret = argv[i+1];
		(*argc) -= 2;
		while (i < *argc) {
		    argv[i] = argv[i+2];
		    i++;
		}
		argv[i] = NULL;
		return ret;
	    }
	}
    }
    return NULL;
}
    

/************************** OS info *******************************/

/* Used by erlang:info/1. */
/* (This code was formerly in drv.XXX/XXX_os_drv.c) */

char os_type[] = "win32";

void
os_flavor(char *namebuf, unsigned size)
{
    switch (int_os_version.dwPlatformId) {
    case VER_PLATFORM_WIN32_WINDOWS:
	strcpy(namebuf, "windows");
	break;
    case VER_PLATFORM_WIN32_NT:
	strcpy(namebuf, "nt");
	break;
    default:			/* Can't happen. */
	strcpy(namebuf, "unknown");
	break;
    }
}

void
os_version(pMajor, pMinor, pBuild)
int* pMajor;			/* Pointer to major version. */
int* pMinor;			/* Pointer to minor version. */
int* pBuild;			/* Pointer to build number. */
{
  *pMajor = int_os_version.dwMajorVersion;
  *pMinor = int_os_version.dwMinorVersion;
  *pBuild = int_os_version.dwBuildNumber;
}

/************************** Port I/O *******************************/

/* I. Common stuff */

/* II. The spawn/fd/vanilla drivers */

/*
 * Definitions for driver flags.
 */

#define DF_OVR_READY	  1	/* Overlapped result is ready. */
#define DF_EXIT_THREAD	  2	/* The thread should exit. */
#define DF_XLAT_CR	  4	/* The thread should translate CRs. */
#define DF_DROP_IF_INVH   8     /* Drop packages instead of crash if
				   invalid handle (stderr) */
#define DF_THREAD_FLUSHED 16	/* The thread should exit. */

#define OV_BUFFER_PTR(dp) ((LPVOID) ((dp)->ov.Internal))
#define OV_NUM_TO_READ(dp) ((dp)->ov.InternalHigh)

/*
 * This data is used to make overlapped I/O operations work on both
 * Windows NT (using true overlapped I/O) and Windows 95 (using threads).
 */

typedef struct async_io {
  unsigned flags;		/* Driver flags, definitions found above. */
  HANDLE thread;		/* If -1, overlapped I/O is used (Windows NT).
				 * Otherwise, it is the handle of the thread used
				 * for simulating overlapped I/O (Windows 95 and
				 * the console for Windows NT).
				 */
  HANDLE fd;			/* Handle for file or pipe. */
  int async_io_active;          /* if true, a close of the file will signal the event in ov */
  OVERLAPPED ov;		/* Control structure for overlapped reading.
				 * When overlapped reading is simulated with
				 * a thread, the fields are used as follows:
				 *   ov.Internal - Read buffer.
				 *   ov.InternalHigh - Number of bytes to read.
				 * See macros above.
				 */
  HANDLE ioAllowed;		/* The thread will wait for this event
				 * before starting a new read or write.
				 */
  HANDLE flushEvent;		/* Used to signal that a flush should be done. */
  HANDLE flushReplyEvent;	/* Used to signal that a flush has been done. */
  DWORD pendingError;		/* Used to delay presentating an error to Erlang
				 * until the check_io function is entered.
				 */
  DWORD bytesTransferred;	/* Bytes read or write in the last operation.
				 * Valid only when DF_OVR_READY is set.
				 */
  DriverData *dp;               /* Pointer to driver data struct which
				   this struct is part of */
} AsyncIo;


/*
 * Input thread for fd_driver (if fd_driver is running).
 */
static AsyncIo* fd_driver_input = NULL;
static BOOL (WINAPI *fpSetHandleInformation)(HANDLE,DWORD,DWORD);

/*
 * This data is used by the spawn and vanilla drivers.
 * There will be one entry for each port, even if the input
 * and output HANDLES are different.  Since handles are not
 * guaranteed to be small numbers in Win32, we cannot index
 * with them.  I.e. the index for each entry is not equal to
 * none of the file handles.
 */

struct driver_data {
    int totalNeeded;		/* Total number of bytes needed to fill
				 * up the packet header or packet. */
    int bytesInBuffer;		/* Number of bytes read so far in
				 * the input buffer.
				 */
    int inBufSize;		/* Size of input buffer. */
    byte *inbuf;		/* Buffer to use for overlapped read. */
    int outBufSize;		/* Size of output buffer. */
    byte *outbuf;		/* Buffer to use for overlapped write. */
    ErlDrvPort port_num;	/* The port handle. */
    int packet_bytes;		/* 0: continuous stream, 1, 2, or 4: the number
				 * of bytes in the packet header.
				 */
    HANDLE port_pid;		/* PID of the port process. */
    AsyncIo in;			/* Control block for overlapped reading. */
    AsyncIo out;		/* Control block for overlapped writing. */
    int report_exit;            /* Do report exit status for the port */
    erts_atomic32_t refc;       /* References to this struct */
};

/* Driver interfaces */
static ErlDrvData spawn_start(ErlDrvPort, char*, SysDriverOpts*);
static ErlDrvData fd_start(ErlDrvPort, char*, SysDriverOpts*);
static ErlDrvData vanilla_start(ErlDrvPort, char*, SysDriverOpts*);
static int spawn_init(void);
static int fd_init(void);
static void fd_stop(ErlDrvData);
static void stop(ErlDrvData);
static void output(ErlDrvData, char*, ErlDrvSizeT);
static void ready_input(ErlDrvData, ErlDrvEvent);
static void ready_output(ErlDrvData, ErlDrvEvent);
static void stop_select(ErlDrvEvent, void*);

struct erl_drv_entry spawn_driver_entry = {
    spawn_init,
    spawn_start,
    stop,
    output,
    ready_input,
    ready_output,
    "spawn",
    NULL, /* finish */
    NULL, /* handle */
    NULL, /* control */
    NULL, /* timeout */
    NULL, /* outputv */
    NULL, /* ready_async */
    NULL, /* flush */
    NULL, /* call */
    NULL, /* event */
    ERL_DRV_EXTENDED_MARKER,
    ERL_DRV_EXTENDED_MAJOR_VERSION,
    ERL_DRV_EXTENDED_MINOR_VERSION,
    0,	/* ERL_DRV_FLAGs */
    NULL,
    NULL, /* process_exit */
    stop_select
};

#ifdef HARD_POLL_DEBUG
extern void poll_debug_set_active_fd(ErtsSysFdType fd);
extern void poll_debug_read_begin(ErtsSysFdType fd);
extern void poll_debug_read_done(ErtsSysFdType fd, int bytes);
extern void poll_debug_async_initialized(ErtsSysFdType fd);
extern void poll_debug_async_immediate(ErtsSysFdType fd, int bytes);
extern void poll_debug_write_begin(ErtsSysFdType fd);
extern void poll_debug_write_done(ErtsSysFdType fd, int bytes);
#endif

extern int null_func(void);

struct erl_drv_entry fd_driver_entry = {
    fd_init,
    fd_start,
    fd_stop,
    output,
    ready_input,
    ready_output,
    "fd",
    NULL, /* finish */
    NULL, /* handle */
    NULL, /* control */
    NULL, /* timeout */
    NULL, /* outputv */
    NULL, /* ready_async */
    NULL, /* flush */
    NULL, /* call */
    NULL, /* event */
    ERL_DRV_EXTENDED_MARKER,
    ERL_DRV_EXTENDED_MAJOR_VERSION,
    ERL_DRV_EXTENDED_MINOR_VERSION,
    0,	/* ERL_DRV_FLAGs */
    NULL,
    NULL, /* process_exit */
    stop_select
};

struct erl_drv_entry vanilla_driver_entry = {
    null_func,
    vanilla_start,
    stop,
    output,
    ready_input,
    ready_output,
    "vanilla",
    NULL, /* finish */
    NULL, /* handle */
    NULL, /* control */
    NULL, /* timeout */
    NULL, /* outputv */
    NULL, /* ready_async */
    NULL, /* flush */
    NULL, /* call */
    NULL, /* event */
    ERL_DRV_EXTENDED_MARKER,
    ERL_DRV_EXTENDED_MAJOR_VERSION,
    ERL_DRV_EXTENDED_MINOR_VERSION,
    0,	/* ERL_DRV_FLAGs */
    NULL,
    NULL, /* process_exit */
    stop_select
};

static ERTS_INLINE void
refer_driver_data(DriverData *dp)
{
#ifdef DEBUG
    erts_aint32_t refc = erts_atomic32_inc_read_nob(&dp->refc);
    ASSERT(refc > 1);
#else
    erts_atomic32_inc_nob(&dp->refc);
#endif
}

static ERTS_INLINE void
unrefer_driver_data(DriverData *dp)
{
    erts_aint32_t refc = erts_atomic32_dec_read_mb(&dp->refc);
    ASSERT(refc >= 0);
    if (refc == 0)
	driver_free(dp);
}

/*
 * Initialises a DriverData structure.
 *
 * Results: Returns a pointer to a DriverData structure, or NULL
 * if the initialsation failed.
 */

static DriverData*
new_driver_data(ErlDrvPort port_num, int packet_bytes, int wait_objs_required, int use_threads)
{
    DriverData* dp;

    DEBUGF(("new_driver_data(%p, pb %d)\n", port_num, packet_bytes));

    dp = driver_alloc(sizeof(DriverData));
    if (!dp)
	return NULL;
    /*
     * We used to test first at all that there is enough room in the
     * array used by WaitForMultipleObjects(), but that is not necessary
     * any more, since driver_select() can't fail.
     */

    erts_atomic32_init_nob(&dp->refc, 1);
    dp->bytesInBuffer = 0;
    dp->totalNeeded = packet_bytes;
    dp->inBufSize = PORT_BUFSIZ;
    dp->inbuf = DRV_BUF_ALLOC(dp->inBufSize);
    if (dp->inbuf == NULL)
	goto buf_alloc_error;
    erts_atomic_add_nob(&sys_misc_mem_sz, dp->inBufSize);
    dp->outBufSize = 0;
    dp->outbuf = NULL;
    dp->port_num = port_num;
    dp->packet_bytes = packet_bytes;
    dp->port_pid = INVALID_HANDLE_VALUE;
    if (init_async_io(dp, &dp->in, use_threads) == -1)
	goto async_io_error1;
    if (init_async_io(dp, &dp->out, use_threads) == -1)
	goto async_io_error2;

    return dp;

async_io_error2:
    release_async_io(&dp->in, dp->port_num);
async_io_error1:
    release_async_io(&dp->out, dp->port_num);

buf_alloc_error:
    driver_free(dp);
    return NULL;
}

static void
release_driver_data(DriverData* dp)
{
#ifdef USE_CANCELIOEX
    if (fpCancelIoEx != NULL) {
	if (dp->in.thread == (HANDLE) -1 && dp->in.fd != INVALID_HANDLE_VALUE) {
	    (*fpCancelIoEx)(dp->in.fd, NULL);
	}
	if (dp->out.thread == (HANDLE) -1 && dp->out.fd != INVALID_HANDLE_VALUE) {
	    (*fpCancelIoEx)(dp->out.fd, NULL);
	}
    }
    else
#endif
    {
	/* This is a workaround for the fact that CancelIo cant cancel
	   requests issued by another thread and that we cant use
	   CancelIoEx as that's only available in Vista etc.
	   R14: Avoid scheduler deadlock by only wait for 10ms, and then spawn
	    a thread that will keep waiting in in order to close handles. */
	HANDLE handles[2];
	int i = 0;
	int timeout = 10;
	if(dp->in.async_io_active && dp->in.fd != INVALID_HANDLE_VALUE) {
	    CloseHandle(dp->in.fd);
	    dp->in.fd = INVALID_HANDLE_VALUE;
	    DEBUGF(("Waiting for the in event thingie"));
	    if (WaitForSingleObject(dp->in.ov.hEvent,timeout) == WAIT_TIMEOUT) {
		close_active_handle(dp, dp->in.ov.hEvent);
		dp->in.ov.hEvent = NULL;
		timeout = 0;
	    }
	    DEBUGF(("...done\n"));
	}
	if(dp->out.async_io_active && dp->out.fd != INVALID_HANDLE_VALUE) {
	    CloseHandle(dp->out.fd);
	    dp->out.fd = INVALID_HANDLE_VALUE;
	    DEBUGF(("Waiting for the out event thingie"));
	    if (WaitForSingleObject(dp->out.ov.hEvent,timeout) == WAIT_TIMEOUT) {
		close_active_handle(dp, dp->out.ov.hEvent);
		dp->out.ov.hEvent = NULL;
	    }
	    DEBUGF(("...done\n"));
	}
    }

    if (dp->inbuf != NULL) {
	ASSERT(erts_atomic_read_nob(&sys_misc_mem_sz) >= dp->inBufSize);
	erts_atomic_add_nob(&sys_misc_mem_sz, -1*dp->inBufSize);
	DRV_BUF_FREE(dp->inbuf);
	dp->inBufSize = 0;
	dp->inbuf = NULL;
    }
    ASSERT(dp->inBufSize == 0);

    if (dp->outbuf != NULL) {
	ASSERT(erts_atomic_read_nob(&sys_misc_mem_sz) >= dp->outBufSize);
	erts_atomic_add_nob(&sys_misc_mem_sz, -1*dp->outBufSize);
	DRV_BUF_FREE(dp->outbuf);
	dp->outBufSize = 0;
	dp->outbuf = NULL;
    }
    ASSERT(dp->outBufSize == 0);

    if (dp->port_pid != INVALID_HANDLE_VALUE) {
	CloseHandle(dp->port_pid);
	dp->port_pid = INVALID_HANDLE_VALUE;
    }

    release_async_io(&dp->in, dp->port_num);
    release_async_io(&dp->out, dp->port_num);

    /*
     * This must be last, because this function might be executed from
     * the exit thread.
     */

    unrefer_driver_data(dp);
}


struct handles_to_be_closed {
    HANDLE handles[MAXIMUM_WAIT_OBJECTS];
    DriverData *drv_data[MAXIMUM_WAIT_OBJECTS];
    unsigned cnt;
};
static struct handles_to_be_closed* htbc_curr = NULL;
CRITICAL_SECTION htbc_lock;

static void close_active_handle(DriverData *dp, HANDLE handle)
{
    struct handles_to_be_closed* htbc;
    int i;
    EnterCriticalSection(&htbc_lock);
    htbc = htbc_curr;
    if (htbc == NULL || htbc->cnt >= MAXIMUM_WAIT_OBJECTS) {
	DWORD tid;
	HANDLE thread;

	htbc = (struct handles_to_be_closed*) erts_alloc(ERTS_ALC_T_DRV_TAB,
							 sizeof(*htbc));
	htbc->handles[0] = CreateAutoEvent(FALSE);
	htbc->drv_data[0] = NULL;
	htbc->cnt = 1;
	thread = (HANDLE *) _beginthreadex(NULL, 0, threaded_handle_closer, htbc, 0, &tid);
	CloseHandle(thread);
    }
    i = htbc->cnt++;
    htbc->handles[i] = handle;
    htbc->drv_data[i] = dp;
    if (dp)
	refer_driver_data(dp); /* Need to keep driver data until we have
				  closed the event; outstanding operation
				  might write into it.. */
    SetEvent(htbc->handles[0]);
    htbc_curr = htbc;
    LeaveCriticalSection(&htbc_lock);
}

static DWORD WINAPI
threaded_handle_closer(LPVOID param)
{
    struct handles_to_be_closed* htbc = (struct handles_to_be_closed*) param;
    unsigned ix;
    DWORD res;
    DEBUGF(("threaded_handle_closer %p started\r\n", htbc));
    EnterCriticalSection(&htbc_lock);
    for (;;) {
	{
	    HANDLE* handles = htbc->handles;
	    unsigned cnt = htbc->cnt;
	    DWORD timeout = (htbc == htbc_curr) ? INFINITE : 10*1000;

	    LeaveCriticalSection(&htbc_lock);
	    DEBUGF(("threaded_handle_closer %p waiting for %d handles\r\n", htbc, cnt));
	    res = WaitForMultipleObjects(cnt, handles, FALSE, timeout);
	}
	EnterCriticalSection(&htbc_lock);
	switch (res) {
	case WAIT_OBJECT_0:
	case WAIT_TIMEOUT:
	    break; /* got some more handles to wait for maybe */
	default:
	    ix = res - WAIT_OBJECT_0;
	    if (ix > 0 && ix < htbc->cnt) {
		int move_ix;
		CloseHandle(htbc->handles[ix]);
		if (htbc->drv_data[ix])
		    unrefer_driver_data(htbc->drv_data[ix]);
		move_ix = --htbc->cnt;
		htbc->handles[ix] = htbc->handles[move_ix];
		htbc->drv_data[ix] = htbc->drv_data[move_ix];
	    }
	}
	if (htbc != htbc_curr) {
	    if (htbc->cnt == 1) { /* no real handles left */
		break;
	    }
	    /* The thread with most free slots will be "current" */
	    if (htbc->cnt < htbc_curr->cnt) {
		htbc_curr = htbc;
		DEBUGF(("threaded_handle_closer %p made current\r\n", htbc));
	    }
	}
    }
    LeaveCriticalSection(&htbc_lock);
    CloseHandle(htbc->handles[0]);
    ASSERT(!htbc->drv_data[0]);
    erts_free(ERTS_ALC_T_DRV_TAB, htbc);
    DEBUGF(("threaded_handle_closer %p terminating\r\n", htbc));
    return 0;
}

/*
 * Stores input and output file descriptors in the DriverData structure,
 * and calls driver_select().
 *
 * This function fortunately can't fail!
 */

static ErlDrvData
set_driver_data(DriverData* dp, HANDLE ifd, HANDLE ofd, int read_write, int report_exit)
{
    int result;

    dp->in.fd = ifd;
    dp->out.fd = ofd;
    dp->report_exit = report_exit;

    if (read_write & DO_READ) {
	result = driver_select(dp->port_num, (ErlDrvEvent)dp->in.ov.hEvent,
			       ERL_DRV_READ|ERL_DRV_USE, 1);
	ASSERT(result != -1);
	async_read_file(&dp->in, dp->inbuf, dp->inBufSize);
    }

    if (read_write & DO_WRITE) {
	result = driver_select(dp->port_num, (ErlDrvEvent)dp->out.ov.hEvent,
			       ERL_DRV_WRITE|ERL_DRV_USE, 1);
	ASSERT(result != -1);
    }
    return (ErlDrvData) dp;
}

static ErlDrvData
reuse_driver_data(DriverData *dp, HANDLE ifd, HANDLE ofd, int read_write, ErlDrvPort port_num)
{
    int result;

    dp->port_num = port_num;
    dp->in.fd = ifd;
    dp->out.fd = ofd;
    dp->report_exit = 0;

    if (read_write & DO_READ) {
	result = driver_select(dp->port_num, (ErlDrvEvent)dp->in.ov.hEvent,
			       ERL_DRV_READ|ERL_DRV_USE, 1);
	ASSERT(result != -1);
    }

    if (read_write & DO_WRITE) {
	result = driver_select(dp->port_num, (ErlDrvEvent)dp->out.ov.hEvent,
			       ERL_DRV_WRITE|ERL_DRV_USE, 1);
	ASSERT(result != -1);
    }
    return (ErlDrvData) dp;
}

/*
 * Initialises an AsyncIo structure.
 */

static int
init_async_io(DriverData *dp, AsyncIo* aio, int use_threads)
{
    aio->dp = dp;
    aio->flags = 0;
    aio->thread = (HANDLE) -1;
    aio->fd = INVALID_HANDLE_VALUE;
    aio->ov.hEvent = NULL;
    aio->ov.Offset = 0L;
    aio->ov.OffsetHigh = 0L;
    aio->ioAllowed = NULL;
    aio->flushEvent = NULL;
    aio->flushReplyEvent = NULL;
    aio->pendingError = 0;
    aio->bytesTransferred = 0;
    aio->async_io_active = 0;
    aio->ov.hEvent = CreateManualEvent(FALSE);
    if (aio->ov.hEvent == NULL)
	return -1;
    if (use_threads) {
	OV_BUFFER_PTR(aio) = NULL;
	OV_NUM_TO_READ(aio) = 0;
	aio->ioAllowed = CreateAutoEvent(FALSE);
	if (aio->ioAllowed == NULL)
	    return -1;
	aio->flushEvent = CreateAutoEvent(FALSE);
	if (aio->flushEvent == NULL)
	  return -1;
	aio->flushReplyEvent = CreateAutoEvent(FALSE);
	if (aio->flushReplyEvent == NULL)
	  return -1;
    }
    return 0;
}

/*
 * Releases everything allocated in an AsyncIo structure.
 */  

static void
release_async_io(AsyncIo* aio, ErlDrvPort port_num)
{
    aio->flags = 0;

    if (aio->thread != (HANDLE) -1)
	CloseHandle(aio->thread);
    aio->thread = (HANDLE) -1;

    if (aio->fd != INVALID_HANDLE_VALUE)
	CloseHandle(aio->fd);
    aio->fd = INVALID_HANDLE_VALUE;

    if (aio->ov.hEvent != NULL)
	CloseHandle(aio->ov.hEvent);

    aio->ov.hEvent = NULL;

    if (aio->ioAllowed != NULL)
	CloseHandle(aio->ioAllowed);
    aio->ioAllowed = NULL;

    if (aio->flushEvent != NULL)
	CloseHandle(aio->flushEvent);
    aio->flushEvent = NULL;

    if (aio->flushReplyEvent != NULL)
	CloseHandle(aio->flushReplyEvent);
    aio->flushReplyEvent = NULL;
}

/* ----------------------------------------------------------------------
 * async_read_file --
 *	Initiaties an asynchronous file read, or simulates that using
 *	the thread associated with this driver data.  To get the results,
 *	call get_overlapped_result().
 *
 * Results:
 *	None.
 * ----------------------------------------------------------------------
 */

static void
async_read_file(AsyncIo* aio, LPVOID buf, DWORD numToRead)
{
    aio->pendingError = NO_ERROR;
#ifdef HARD_POLL_DEBUG
    poll_debug_async_initialized(aio->ov.hEvent);
#endif
    if (aio->thread != (HANDLE) -1) {
	DEBUGF(("async_read_file: signaling thread 0x%x, event 0x%x\n",
		aio->thread, aio->ioAllowed));
	OV_BUFFER_PTR(aio) = buf;
	OV_NUM_TO_READ(aio) = numToRead;
	ResetEvent(aio->ov.hEvent);
	SetEvent(aio->ioAllowed);
    } else {
	aio->async_io_active = 1; /* Will get 0 when the event actually happened */
	if (ReadFile(aio->fd, buf, numToRead,
		     &aio->bytesTransferred, &aio->ov)) {
	    DEBUGF(("async_read_file: ReadFile() suceeded: %d bytes\n",
		    aio->bytesTransferred));
#ifdef HARD_POLL_DEBUG
	    poll_debug_async_immediate(aio->ov.hEvent, aio->bytesTransferred);
#endif
	    aio->flags |= DF_OVR_READY;
	    SetEvent(aio->ov.hEvent);
	} else {
	    DWORD error = GetLastError();
	    if (error != ERROR_IO_PENDING) {
#ifdef HARD_POLL_DEBUG
		poll_debug_async_immediate(aio->ov.hEvent, 0);
#endif
		aio->pendingError = error;
		SetEvent(aio->ov.hEvent);
	    }
	    DEBUGF(("async_read_file: ReadFile() -> %s\n", win32_errorstr(error)));
	}
    }
}

/* ----------------------------------------------------------------------
 * async_write_file --
 *	Initiaties an asynchronous file write, or simulates that using
 *	the output thread associated with this driver data. 
 *	To get the results, call get_overlapped_result().
 *
 * Results:
 *	None.
 * ----------------------------------------------------------------------
 */
static int
async_write_file(AsyncIo* aio,		/* Pointer to async control block. */
		 LPVOID buf,		/* Pointer to buffer with data to write. */
		 DWORD numToWrite)	/* Number of bytes to write. */
{
    aio->pendingError = NO_ERROR;
    if (aio->thread != (HANDLE) -1) {
	DEBUGF(("async_write_file: signaling thread 0x%x, event 0x%x\n",
		aio->thread, aio->ioAllowed));
	OV_BUFFER_PTR(aio) = buf;
	OV_NUM_TO_READ(aio) = numToWrite;
	ResetEvent(aio->ov.hEvent);
	SetEvent(aio->ioAllowed);
    } else {
	aio->async_io_active = 1; /* Will get 0 when the event actually happened */
	if (WriteFile(aio->fd, buf, numToWrite,
		      &aio->bytesTransferred, &aio->ov)) {
	    DEBUGF(("async_write_file: WriteFile() suceeded: %d bytes\n",
		    aio->bytesTransferred));
	    aio->async_io_active = 0; /* The event will not be signalled */
	    ResetEvent(aio->ov.hEvent);
	    return TRUE;
	} else {
	    DWORD error = GetLastError();
	    if (error != ERROR_IO_PENDING) {
		aio->pendingError = error;
		SetEvent(aio->ov.hEvent);
	    }
	    DEBUGF(("async_write_file: WriteFile() -> %s\n", win32_errorstr(error)));
	}
    }
    return FALSE;
}

/* ----------------------------------------------------------------------
 * get_overlapped_result --
 *
 * Results:
 *	Returns the error code for the overlapped result, or NO_ERROR
 *	if no error.
 * ----------------------------------------------------------------------
 */
static int
get_overlapped_result(AsyncIo* aio,		/* Pointer to async control block. */
		      LPDWORD pBytesRead,	/* Where to place the number of bytes
						 * transferred.
						 */
		      BOOL wait			/* If true, wait until result is ready. */
		      )
{
    DWORD error = NO_ERROR;	/* Error status from last function. */

    if (aio->thread != (HANDLE) -1) {

	/*
	 * Simulate overlapped io with a thread.
	 */
	DEBUGF(("get_overlapped_result: about to wait for event 0x%x\n",
		aio->ov.hEvent));
	error = WaitForSingleObject(aio->ov.hEvent, wait ? INFINITE : 0);
	switch (error) {
	case WAIT_OBJECT_0:
	    error = aio->pendingError;
	    aio->pendingError = NO_ERROR;
	    *pBytesRead = aio->bytesTransferred;
	    ResetEvent(aio->ov.hEvent);
	    DEBUGF(("get_overlapped_result -> %s\n",
		    win32_errorstr(error)));
	    return error;
	case WAIT_TIMEOUT:
	    DEBUGF(("get_overlapped_result -> %s\n",
		    ERROR_IO_INCOMPLETE));
	    return ERROR_IO_INCOMPLETE;
	case WAIT_FAILED:		/* XXX: Shouldn't happen? */
	    error = GetLastError();
	    DEBUGF(("get_overlapped_result (WAIT_FAILED) -> %s\n",
		    win32_errorstr(error)));
	    return error;
	}
    } else if (aio->pendingError != NO_ERROR) { /* Pending error. */
	error = aio->pendingError;
	aio->pendingError = NO_ERROR;
	ResetEvent(aio->ov.hEvent);
	DEBUGF(("get_overlapped_result: pending error: %s\n",
		win32_errorstr(error)));
	return error;
    } else if (aio->flags & DF_OVR_READY) { /* Operation succeded. */
	aio->flags &= ~DF_OVR_READY;
	*pBytesRead = aio->bytesTransferred;
	ResetEvent(aio->ov.hEvent);
	DEBUGF(("get_overlapped_result: delayed success: %d bytes\n",
		aio->bytesTransferred));
    } else if (!GetOverlappedResult(aio->fd, &aio->ov, pBytesRead, wait)) {
	error = GetLastError();
	ResetEvent(aio->ov.hEvent);
	DEBUGF(("get_overlapped_result: error: %s\n", win32_errorstr(error)));
	return error;
    } else {			/* Success. */
	DEBUGF(("get_overlapped_result: success\n"));
	ResetEvent(aio->ov.hEvent);
    }
    return NO_ERROR;
}
  
static int
fd_init(void)
{
    char kernel_dll_name[] = "kernel32";
    HMODULE module;
    module = GetModuleHandle(kernel_dll_name);
    fpSetHandleInformation = (module != NULL) ? 
	(BOOL (WINAPI *)(HANDLE,DWORD,DWORD)) 
	GetProcAddress(module,"SetHandleInformation") : 
	NULL;

    return 0;
}
static int
spawn_init(void)
{
    int i;
#if defined(USE_CANCELIOEX)
    HMODULE module = GetModuleHandle("kernel32");
    fpCancelIoEx = (BOOL (WINAPI *)(HANDLE,LPOVERLAPPED))
	((module != NULL) ? GetProcAddress(module,"CancelIoEx") : NULL);
    DEBUGF(("fpCancelIoEx = %p\r\n", fpCancelIoEx));
#endif

    return 0;
}

static ErlDrvData
spawn_start(ErlDrvPort port_num, char* utf8_name, SysDriverOpts* opts)
{
    HANDLE hToChild = INVALID_HANDLE_VALUE; /* Write handle to child. */
    HANDLE hFromChild = INVALID_HANDLE_VALUE; /* Read handle from child. */
    HANDLE hChildStdin = INVALID_HANDLE_VALUE;		/* Child's stdin. */
    HANDLE hChildStdout = INVALID_HANDLE_VALUE;	/* Child's stout. */
    HANDLE hChildStderr = INVALID_HANDLE_VALUE;	/* Child's sterr. */
    DWORD pid;
    int close_child_stderr = 0;
    DriverData* dp;		/* Pointer to driver data. */
    ErlDrvData retval = ERL_DRV_ERROR_GENERAL; /* Return value. */
    int ok;
    int neededSelects = 0;
    SECURITY_ATTRIBUTES sa = {sizeof(SECURITY_ATTRIBUTES), NULL, TRUE};
    int errno_return = -1;
    wchar_t *name;
    int len;

    if (opts->read_write & DO_READ)
	neededSelects++;
    if (opts->read_write & DO_WRITE)
	neededSelects++;

    if ((dp = new_driver_data(port_num, opts->packet_bytes, neededSelects,
			      !use_named_pipes)) == NULL)
	return ERL_DRV_ERROR_GENERAL;

    /*
     * Create two pipes to communicate with the port program.
     */

    if (opts->read_write & DO_READ) {
	if (!create_pipe(&hFromChild, &hChildStdout, FALSE, 
			 opts->overlapped_io))
	    goto error;
    } else {
	hChildStdout = CreateFile("nul", GENERIC_WRITE, 0,
				  &sa, OPEN_EXISTING,
				  FILE_ATTRIBUTE_NORMAL, NULL);
	DEBUGF(("Created nul file for hChildStdout = %d\n",hChildStdout));
    }
    if (opts->read_write & DO_WRITE) {
	if (!create_pipe(&hChildStdin, &hToChild, TRUE, opts->overlapped_io)) {
	    CloseHandle(hFromChild);
	    hFromChild = INVALID_HANDLE_VALUE;
	    CloseHandle(hChildStdout);
	    goto error;
	}
    } else {
	hChildStdin = CreateFile("nul", GENERIC_READ, 0,
				 &sa, OPEN_EXISTING,
				 FILE_ATTRIBUTE_NORMAL, NULL);
	DEBUGF(("Created nul file for hChildStdin = %d\n",hChildStdin));
    }	

    /*
     * Make sure that standard error is valid handle, because a Command Prompt
     * window not work properly otherwise.  We leave standard error alone if
     * it is okay and no redirection was specified.
     */
    hChildStderr = GetStdHandle(STD_ERROR_HANDLE);
    if (opts->redir_stderr) {
	hChildStderr = hChildStdout;
    } else if (hChildStderr == INVALID_HANDLE_VALUE || hChildStderr == 0) {
	hChildStderr = CreateFile("nul", GENERIC_WRITE, 0, &sa, OPEN_EXISTING,
				  FILE_ATTRIBUTE_NORMAL, NULL);
	close_child_stderr = 1;
    }
    if (fpSetHandleInformation != NULL) {
	(*fpSetHandleInformation)(hChildStderr, HANDLE_FLAG_INHERIT, 1);
    }
    /*
     * Spawn the port program.
     */

    if ((len = MultiByteToWideChar(CP_UTF8, 0, utf8_name, -1, NULL, 0)) > 0) {
	name = erts_alloc(ERTS_ALC_T_TMP, len*sizeof(wchar_t));
	MultiByteToWideChar(CP_UTF8, 0, utf8_name, -1, name, len);
    } else { /* Not valid utf-8, just convert byte to wchar */
	int i;
	len  = strlen(utf8_name);
	name = erts_alloc(ERTS_ALC_T_TMP, (1+len)*sizeof(wchar_t));
	for(i=0; i<len; i++) {
	    name[i] = (wchar_t) utf8_name[i];
	}
	name[i] = L'\0';
    }
    DEBUGF(("Spawning \"%S\"\n", name));

    {
        void *environment_block = build_env_block(&opts->envir);

        ok = create_child_process(name,
                                  hChildStdin,
                                  hChildStdout,
                                  hChildStderr,
                                  &dp->port_pid,
                                  &pid,
                                  opts->hide_window,
                                  environment_block,
                                  (wchar_t *) opts->wd,
                                  opts->spawn_type,
                                  (wchar_t **) opts->argv,
                                  &errno_return);

        CloseHandle(hChildStdin);
        CloseHandle(hChildStdout);

        if (close_child_stderr && hChildStderr != INVALID_HANDLE_VALUE &&
            hChildStderr != 0) {
            CloseHandle(hChildStderr);
        }

        erts_free(ERTS_ALC_T_TMP, environment_block);
        erts_free(ERTS_ALC_T_TMP, name);
    }

    if (!ok) {
	dp->port_pid = INVALID_HANDLE_VALUE;
	if (errno_return >= 0) {
	    retval = ERL_DRV_ERROR_ERRNO;
	} 
    } else {
	if (!use_named_pipes) {
	    if ((opts->read_write & DO_READ) &&
		!create_file_thread(&dp->in, DO_READ))
		goto error;
	    if ((opts->read_write & DO_WRITE) &&
		!create_file_thread(&dp->out, DO_WRITE)) {
		dp->in.flags = DF_EXIT_THREAD;
		SetEvent(dp->in.ioAllowed);
		WaitForSingleObject(dp->in.thread, INFINITE);
		dp->in.thread = (HANDLE) -1;
		goto error;
	    }
	}
#ifdef HARD_POLL_DEBUG
	if (strncmp(name,"inet_gethost",12) == 0) {
	    erts_printf("Debugging \"%s\"\n", name);
	    poll_debug_set_active_fd(dp->in.ov.hEvent);
	}
#endif
	retval = set_driver_data(dp, hFromChild, hToChild, opts->read_write,
				 opts->exit_status);
	if (retval != ERL_DRV_ERROR_GENERAL && retval != ERL_DRV_ERROR_ERRNO) {
            /* We assume that this cannot generate a negative number */
            erl_drv_set_os_pid(port_num, pid);
	}
    }
    
    if (retval != ERL_DRV_ERROR_GENERAL && retval != ERL_DRV_ERROR_ERRNO)
	return retval;
    
 error:
    if (hFromChild != INVALID_HANDLE_VALUE)
	CloseHandle(hFromChild);
    if (hToChild != INVALID_HANDLE_VALUE)
	CloseHandle(hToChild);
    release_driver_data(dp);
    if (retval == ERL_DRV_ERROR_ERRNO) {
	errno = errno_return;
    }
    return retval;
}

struct __build_env_state {
    WCHAR *next_variable;
};

static void build_env_foreach(void *_state, const erts_osenv_data_t *key,
                              const erts_osenv_data_t *value)
{
    struct __build_env_state *state = (struct __build_env_state*)(_state);

    sys_memcpy(state->next_variable, key->data, key->length);
    state->next_variable += (int)key->length / sizeof(WCHAR);
    *state->next_variable++ = L'=';

    sys_memcpy(state->next_variable, value->data, value->length);
    state->next_variable += (int)value->length / sizeof(WCHAR);
    *state->next_variable++ = L'\0';
}

/* Builds an environment block suitable for CreateProcessW. */
static void *build_env_block(const erts_osenv_t *env) {
    struct __build_env_state build_state;
    WCHAR *env_block;

    env_block = erts_alloc(ERTS_ALC_T_TMP, env->content_size +
        (env->variable_count * sizeof(L"=\0") + sizeof(L'\0')));

    build_state.next_variable = env_block;

    erts_osenv_foreach_native(env, &build_state, build_env_foreach);

    (*build_state.next_variable) = L'\0';

    return env_block;
}

static int
create_file_thread(AsyncIo* aio, int mode)
{
    DWORD tid;			/* Id for thread. */

    refer_driver_data(aio->dp);
    aio->thread = (HANDLE)
	_beginthreadex(NULL, 0, 
		       (mode & DO_WRITE) ? threaded_writer : threaded_reader,
		       aio, 0, &tid);
    if (aio->thread != (HANDLE) -1)
	return 1;
    unrefer_driver_data(aio->dp);
    return 0;
}

/* 
 *  A helper function used by create_child_process().
 *  Parses a command line with arguments and returns the length of the
 *  first part containing the program name.
 *  Example: input = "\"Program Files\"\\erl arg1 arg2"
 *  gives 19 as result.
 *  The length returned is equivalent with length(argv[0]) if the
 *  command line should have been prepared by _setargv for the main function
*/
int parse_command(wchar_t* cmd){
#define NORMAL 2
#define STRING 1
#define STOP 0
    int i =0;
    int state = NORMAL;
    while (cmd[i]) {
	switch (cmd[i]) {
	case L'"':
	    if (state == NORMAL) 
		state = STRING;
	    else
		state = NORMAL;
	    break;
	case L'\\':
	    if ((state == STRING) && (cmd[i+1]==L'"'))
		i++;
	    break;
	case L' ':
	    if (state == NORMAL)
		state = STOP;
	    break;
	default:
	    break;
	}
	if (state == STOP) {
	    return i;
	}
	i++;
    }
    return i;
}


/*
 * Translating of command line arguments to correct format. In the examples
 * below the '' are not part of the actual string. 
 * 'io:format("hello").' -> 'io:format(\"hello\").'
 * 'io:format("is anybody in there?").' -> '"io:format(\"is anybody in there?\")."'
 * 'Just nod if you can hear me.' -> '"Just nod if you can hear me."'
 * 'Is there ""anyone at home?' -> '"Is there \"\"anyone at home?"'
 * 'Relax."' -> 'Relax.\"'
 *
 * If new == NULL we just calculate the length.
 *
 * The reason for having to quote all of the is because CreateProcessW removes
 * one level of escaping since it takes a single long command line rather
 * than the argument chunks that unix uses.
 */
static int escape_and_quote(wchar_t *str, wchar_t *new, BOOL *quoted) {
    int i, j = 0;
    if (new == NULL)
        *quoted = FALSE;
    else if (*quoted)
        new[j++] = L'"';
    for ( i = 0; str[i] != L'\0'; i++,j++) {
        if (str[i] == L' ' && new == NULL && *quoted == FALSE) {
	    *quoted = TRUE;
	    j++;
	}
	/* check if we have to escape quotes */
	if (str[i] == L'"') {
	    if (new) new[j] = L'\\';
	    j++;
	}
	if (new) new[j] = str[i];
    }
    if (*quoted) {
        if (new) new[j] = L'"';
	j++;
    }
    return j;
}

/*
 *----------------------------------------------------------------------
 *
 * create_child_process --
 *
 *	Create a child process that has pipes as its 
 *	standard input, output, and error.  The child process runs
 *	synchronously under Win32s and asynchronously under Windows NT
 *	and Windows 95, and runs with the same environment variables
 *	as the creating process.
 *
 *	The complete Windows search path is searched to find the specified 
 *	executable.  If an executable by the given name is not found, 
 *	automatically tries appending ".com", ".exe", and ".bat" to the 
 *	executable name.
 *
 * Results:
 *	The return value is FALSE if there was a problem creating the child process.  
 *      Otherwise, the return value is 0 and *phPid is
 *	filled with the process id of the child process.
 * 
 * Side effects:
 *	A process is created.
 *	
 *----------------------------------------------------------------------
 */

static BOOL
create_child_process
(
 wchar_t *origcmd,  /* Command line for child process (including
		  * name of executable). Or whole executable if st is
		  * ERTS_SPAWN_EXECUTABLE
		  */
 HANDLE hStdin,  /* The standard input handle for child. */
 HANDLE hStdout, /* The standard output handle for child. */ 
 HANDLE hStderr, /* The standard error handle for child. */
 LPHANDLE phPid, /* Pointer to variable to received Process handle. */
 LPDWORD pdwID,   /* Pointer to variable to received Process ID */
 BOOL hide,      /* Hide the window unconditionally. */
 LPVOID env,     /* Environment for the child */
 wchar_t *wd,      /* Working dir for the child */
 unsigned st,    /* Flags for spawn, tells us how to interpret origcmd */
 wchar_t **argv,     /* Argument vector if given. */
 int *errno_return /* Place to put an errno in in case of failure */
 )
{
    PROCESS_INFORMATION piProcInfo = {0};
    BOOL ok = FALSE;
    int applType;
    /* Not to be changed for different types of executables */
    int staticCreateFlags = GetPriorityClass(GetCurrentProcess()); 
    int createFlags = DETACHED_PROCESS;
    wchar_t *newcmdline = NULL;
    int cmdlength;
    wchar_t* thecommand;
    wchar_t* appname = NULL;
    HANDLE hProcess = GetCurrentProcess();
    STARTUPINFOW siStartInfo = {0};
    wchar_t execPath[MAX_PATH];

    *errno_return = -1;
    siStartInfo.cb = sizeof(STARTUPINFOW);
    siStartInfo.dwFlags = STARTF_USESTDHANDLES;
    siStartInfo.hStdInput = hStdin;
    siStartInfo.hStdOutput = hStdout;
    siStartInfo.hStdError = hStderr;

    if (st != ERTS_SPAWN_EXECUTABLE) {
	/*
	 * Parse out the program name from the command line (it can be quoted and
	 * contain spaces).
	 */
	cmdlength = parse_command(origcmd);
	newcmdline = (wchar_t *) erts_alloc(ERTS_ALC_T_TMP, (MAX_PATH+wcslen(origcmd)-cmdlength)*sizeof(wchar_t));
	thecommand = (wchar_t *) erts_alloc(ERTS_ALC_T_TMP, (cmdlength+1)*sizeof(wchar_t));
	wcsncpy(thecommand, origcmd, cmdlength);
	thecommand[cmdlength] = L'\0';
	DEBUGF(("spawn command: %S\n", thecommand));

	applType = application_type(thecommand, execPath, TRUE, TRUE, errno_return);
	DEBUGF(("application_type returned for (%S) is %d\n", thecommand, applType));
	erts_free(ERTS_ALC_T_TMP, (void *) thecommand);
	if (applType == APPL_NONE) {
	    erts_free(ERTS_ALC_T_TMP,newcmdline);
	    return FALSE;
	}
	newcmdline[0] = L'\0';

	if (applType == APPL_DOS) {
	    /*
	     * Under NT, 16-bit DOS applications will not run unless they
	     * can be attached to a console.  Run the 16-bit program as
	     * a normal process inside of a hidden console application,
	     * and then run that hidden console as a detached process.
	     */

	    siStartInfo.wShowWindow = SW_HIDE;
	    siStartInfo.dwFlags |= STARTF_USESHOWWINDOW;
	    createFlags = CREATE_NEW_CONSOLE;
	    wcscat(newcmdline, L"cmd.exe /c ");
	} else if (hide) {
	    DEBUGF(("hiding window\n"));
	    siStartInfo.wShowWindow = SW_HIDE;
	    siStartInfo.dwFlags |= STARTF_USESHOWWINDOW;
	    createFlags = 0;
	}

	wcscat(newcmdline, execPath);
	wcscat(newcmdline, origcmd+cmdlength);
	DEBUGF(("Creating child process: %S, createFlags = %d\n", newcmdline, createFlags));
	ok = CreateProcessW(appname,
			    newcmdline,
			    NULL,
			    NULL,
			    TRUE,
			    createFlags | staticCreateFlags |
			    CREATE_UNICODE_ENVIRONMENT,
			    env,
			    wd,
			    &siStartInfo,
			    &piProcInfo);

    } else { /* ERTS_SPAWN_EXECUTABLE, filename and args are in unicode ({utf16,little}) */
	int run_cmd = 0;

	applType = application_type(origcmd, execPath, FALSE, FALSE, errno_return);
	if (applType == APPL_NONE) {
	    return FALSE;
	} 
	if (applType == APPL_DOS) {
	    /*
	     * See comment above
	     */
		
	    siStartInfo.wShowWindow = SW_HIDE;
	    siStartInfo.dwFlags |= STARTF_USESHOWWINDOW;
	    createFlags = CREATE_NEW_CONSOLE;
	    run_cmd = 1;
	} else if (hide) {
	    DEBUGF(("hiding window\n"));
	    siStartInfo.wShowWindow = SW_HIDE;
	    siStartInfo.dwFlags |= STARTF_USESHOWWINDOW;
	    createFlags = 0;
	}
	if (run_cmd) {
	    wchar_t cmdPath[MAX_PATH];
	    int cmdType;
	    cmdType = application_type(L"cmd.exe", cmdPath, TRUE, FALSE, errno_return);
	    if (cmdType == APPL_NONE || cmdType == APPL_DOS) {
		return FALSE;
	    }
	    appname = (wchar_t *) erts_alloc(ERTS_ALC_T_TMP, (wcslen(cmdPath)+1)*sizeof(wchar_t));
	    wcscpy(appname,cmdPath);
	} else {
	    appname = (wchar_t *) erts_alloc(ERTS_ALC_T_TMP, (wcslen(execPath)+1)*sizeof(wchar_t));
	    wcscpy(appname, execPath);
	}
	if (argv == NULL) { 
	    BOOL orig_need_q;
	    wchar_t *ptr;
	    int ocl = escape_and_quote(execPath, NULL, &orig_need_q);
	    if (run_cmd) {
		newcmdline = (wchar_t *) erts_alloc(ERTS_ALC_T_TMP,
						    (ocl + 1 + 11)*sizeof(wchar_t));
		memcpy(newcmdline,L"cmd.exe /c ",11*sizeof(wchar_t));
		ptr = newcmdline + 11;
	    } else {
		newcmdline = (wchar_t *) erts_alloc(ERTS_ALC_T_TMP,
						    (ocl + 1)*sizeof(wchar_t));
		ptr = (wchar_t *) newcmdline;
	    }
	    ptr += escape_and_quote(execPath, ptr, &orig_need_q);
	    ptr[0] = L'\0';
	} else {
	    int sum = 0;
	    BOOL *qte = NULL;
	    wchar_t **ar = argv;
	    wchar_t *n;
	    wchar_t *save_arg0 = NULL;
	    if (argv[0] == (wchar_t *) erts_default_arg0 || run_cmd) {
		save_arg0 = argv[0];
		argv[0] = execPath;
	    }
	    if (run_cmd) {
		sum += 11; /* cmd.exe /c */
	    }

	    while (*ar != NULL)  ar++;
	    qte = erts_alloc(ERTS_ALC_T_TMP, (ar - argv)*sizeof(BOOL));

	    ar = argv;
	    while (*ar != NULL) {
		sum += escape_and_quote(*ar,NULL,qte+(ar - argv));
		sum++; /* space */
		++ar;
	    }
	    ar = argv;
	    newcmdline = (wchar_t *) erts_alloc(ERTS_ALC_T_TMP, sum*sizeof(wchar_t));
	    n = newcmdline;
	    if (run_cmd) {
		memcpy(n,L"cmd.exe /c ",11*sizeof(wchar_t));
		n += 11;
	    }
	    while (*ar != NULL) {
		n += escape_and_quote(*ar,n,qte+(ar - argv));
		*n++ = L' ';
		++ar;
	    }
	    *(n-1) = L'\0'; /* overwrite last space with '\0' */
	    if (save_arg0 != NULL) {
		argv[0] = save_arg0;
	    }
	    erts_free(ERTS_ALC_T_TMP, qte);
	}	    
	    
	DEBUGF((stderr,"Creating child process: %S, createFlags = %d\n", newcmdline, createFlags));
	ok = CreateProcessW((wchar_t *) appname,
			    (wchar_t *) newcmdline,
			    NULL,
			    NULL,
			    TRUE,
			    createFlags | staticCreateFlags |
			    CREATE_UNICODE_ENVIRONMENT,
			    env,
			    wd,
			    &siStartInfo,
			    &piProcInfo);

    } /* end SPAWN_EXECUTABLE */
    if (newcmdline != NULL) {
	    erts_free(ERTS_ALC_T_TMP,newcmdline);
    }	
    if (appname != NULL) {
	    erts_free(ERTS_ALC_T_TMP,appname);
    }	
    if (!ok) {
	DEBUGF(("CreateProcess failed: %s\n", last_error()));
	if (*errno_return < 0) {
	    *errno_return = EACCES;
	}
	return FALSE;
    }
    CloseHandle(piProcInfo.hThread); /* Necessary to avoid resource leak. */
    *phPid = piProcInfo.hProcess;
    *pdwID = piProcInfo.dwProcessId;

    if (applType == APPL_DOS) {
	WaitForSingleObject(hProcess, 50);
    }
    
    return ok;
}

/* 
 * Note, inheritRead == FALSE means "inhetitWrite", i e one of the
 * pipe ends is always expected to be inherited. The pipe end that should 
 * be inherited is opened without overlapped io flags, as the child program
 * would expect stdout not to demand overlapped I/O. 
 */
static int create_pipe(HANDLE *phRead, HANDLE *phWrite, BOOL inheritRead, BOOL overlapped_io)
{
    SECURITY_ATTRIBUTES sa = {sizeof(SECURITY_ATTRIBUTES), NULL, TRUE};
    char pipe_name[256];	/* Name of pipe. */
    Uint calls;

    /*
     * If we should't use named pipes, create anonmous pipes.
     */

    if (!use_named_pipes) {
	int success;
	HANDLE non_inherited;	/* Non-inherited copy of handle. */

	if (!CreatePipe(phRead, phWrite, &sa, 0)) {
	    DEBUGF(("Error creating anonyomous pipe: %s\n", last_error()));
	    return FALSE;
	…