windows-nt/Source/XPSP1/NT/base/crts/crtw32/lowio/pipe.c

/***
*pipe.c - create a pipe
*
*       Copyright (c) 1989-2001, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       defines _pipe() - creates a pipe (i.e., an I/O channel for interprocess
*                         communication)
*
*Revision History:
*       06-20-89  PHG   Module created, based on asm version
*       03-13-90  GJF   Made calling type _CALLTYPE2 (for now), added #include
*                       <cruntime.h> and fixed copyright. Also, cleaned up the
*                       formatting a bit.
*       04-03-90  GJF   Now _CALLTYPE1.
*       07-24-90  SBM   Removed '32' from API names
*       08-14-90  SBM   Compiles cleanly with -W3
*       10-01-90  GJF   New-style function declarator.
*       12-04-90  SRW   Changed to include <oscalls.h> instead of <doscalls.h>
*       12-06-90  SRW   Added _CRUISER_ and _WIN32 conditionals.
*       01-18-91  GJF   ANSI naming.
*       02-18-91  SRW   Added _WIN32_ implementation [_WIN32_]
*       02-25-91  SRW   Renamed _get_free_osfhnd to be _alloc_osfhnd [_WIN32_]
*       03-13-91  SRW   Fixed _pipe so it works [_WIN32_]
*       03-18-91  SRW   Fixed _pipe NtCreatePipe handles are inherited [_WIN32_]
*       04-06-92  SRW   Pay attention to _O_NOINHERIT flag in oflag parameter
*       01-10-93  GJF   Fixed bug in checking for _O_BINARY (inadvertently
*                       introduced by SRW's change above).
*       04-06-93  SKS   Replace _CRTAPI* with __cdecl
*       09-06-94  CFW   Remove Cruiser support.
*       12-03-94  SKS   Clean up OS/2 references
*       06-12-95  GJF   Replaced _osfile[] with _osfile() (macro referencing
*                       field in ioinfo struct).
*       05-16-96  GJF   Set the FNOINHERIT bit (new) if appropriate. Also,
*                       detab-ed and cleaned up the formatting a bit.
*       05-31-96  SKS   Fix expression error in GJF's most recent check-in
*       12-29-97  GJF   Exception-safe locking.
*       02-07-98  GJF   Changes for Win64: arg type of _set_osfhnd is now
*                       intptr_t.
*       10-16-00  PML   Avoid deadlock in _alloc_osfhnd (vs7#173087).
*
*******************************************************************************/

#include <cruntime.h>
#include <oscalls.h>
#include <mtdll.h>
#include <io.h>
#include <internal.h>
#include <stdlib.h>
#include <errno.h>
#include <msdos.h>
#include <fcntl.h>

/***
*int _pipe(phandles, psize, textmode) - open a pipe
*
*Purpose:
*       Checks if the given handle is associated with a character device
*       (terminal, console, printer, serial port)
*
*       Multi-thread notes: No locking is performed or deemed necessary. The
*       handles returned by DOSCREATEPIPE are newly opened and, therefore,
*       should not be referenced by any thread until after the _pipe call is
*       complete. The function is not protected from some thread of the caller
*       doing, say, output to a previously invalid handle that becomes one of
*       the pipe handles. However, any such program is doomed anyway and
*       protecting the _pipe function such a case would be of little value.
*
*Entry:
*       int phandle[2] - array to hold returned read (phandle[0]) and write
*                        (phandle[1]) handles
*
*       unsigned psize - amount of memory, in bytes, to ask o.s. to reserve
*                        for the pipe
*
*       int textmode   - _O_TEXT, _O_BINARY, _O_NOINHERIT, or 0 (use default)
*
*Exit:
*       returns 0 if successful
*       returns -1 if an error occurs in which case, errno is set to:
*
*Exceptions:
*
*******************************************************************************/

int __cdecl _pipe (
        int phandles[2],
        unsigned psize,
        int textmode
        )
{
        ULONG dosretval;                    /* o.s. return value */
        int handle0, handle1;

        HANDLE ReadHandle, WriteHandle;
        SECURITY_ATTRIBUTES SecurityAttributes;

        phandles[0] = phandles[1] = -1;

        SecurityAttributes.nLength = sizeof(SecurityAttributes);
        SecurityAttributes.lpSecurityDescriptor = NULL;

        if (textmode & _O_NOINHERIT) {
            SecurityAttributes.bInheritHandle = FALSE;
        }
        else {
            SecurityAttributes.bInheritHandle = TRUE;
        }

        if (!CreatePipe(&ReadHandle, &WriteHandle, &SecurityAttributes, psize)) {
            /* o.s. error */
            dosretval = GetLastError();
            _dosmaperr(dosretval);
            return -1;
        }

        /* now we must allocate C Runtime handles for Read and Write handles */

        if ((handle0 = _alloc_osfhnd()) != -1) {

#ifdef  _MT
            __try {
#endif  /* _MT */

            _osfile(handle0) = (char)(FOPEN | FPIPE | FTEXT);

#ifdef  _MT
            }
            __finally {
                _unlock_fh( handle0 );
            }
#endif  /* _MT */

            if ((handle1 = _alloc_osfhnd()) != -1) {

#ifdef  _MT
                __try {
#endif  /* _MT */

                _osfile(handle1) = (char)(FOPEN | FPIPE | FTEXT);

#ifdef  _MT
                }
                __finally {
                    if ( handle1 != -1 )
                        _unlock_fh( handle1 );
                }
#endif  /* _MT */

                if ( (textmode & _O_BINARY) ||
                     (((textmode & _O_TEXT) == 0) &&
                      (_fmode == _O_BINARY)) ) {
                    /* binary mode */
                    _osfile(handle0) &= ~FTEXT;
                    _osfile(handle1) &= ~FTEXT;
                }

                if ( textmode & _O_NOINHERIT ) {
                    _osfile(handle0) |= FNOINHERIT;
                    _osfile(handle1) |= FNOINHERIT;
                }

                _set_osfhnd(handle0, (intptr_t)ReadHandle);
                _set_osfhnd(handle1, (intptr_t)WriteHandle);
                errno = 0;
            }
            else {
                _osfile(handle0) = 0;
                errno = EMFILE;     /* too many files */
            }
        }
        else {
            errno = EMFILE;     /* too many files */
        }

        /* If error occurred, close Win32 handles and return -1 */
        if (errno != 0) {
            CloseHandle(ReadHandle);
            CloseHandle(WriteHandle);
            _doserrno = 0;      /* not an o.s. error */
            return -1;
        }

        phandles[0] = handle0;
        phandles[1] = handle1;

        return 0;
}