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Tricks of the Windows Gam…ming Gurus (2nd Edition)
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Disc2.iso
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vc98
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crt
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pipe.c
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C/C++ Source or Header
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1998-06-17
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131 lines
/***
*pipe.c - create a pipe
*
* Copyright (c) 1989-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
* defines _pipe() - creates a pipe (i.e., an I/O channel for interprocess
* communication)
*
*******************************************************************************/
#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 */
HANDLE ReadHandle, WriteHandle;
SECURITY_ATTRIBUTES SecurityAttributes;
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 ((phandles[0] = _alloc_osfhnd()) != -1) {
_osfile(phandles[0]) = (char)(FOPEN | FPIPE | FTEXT);
if ((phandles[1] = _alloc_osfhnd()) != -1) {
_osfile(phandles[1]) = (char)(FOPEN | FPIPE | FTEXT);
if ( (textmode & _O_BINARY) ||
(((textmode & _O_TEXT) == 0) &&
(_fmode == _O_BINARY)) ) {
/* binary mode */
_osfile(phandles[0]) &= ~FTEXT;
_osfile(phandles[1]) &= ~FTEXT;
}
if ( textmode & _O_NOINHERIT ) {
_osfile(phandles[0]) |= FNOINHERIT;
_osfile(phandles[1]) |= FNOINHERIT;
}
_set_osfhnd(phandles[0], (long)ReadHandle);
_set_osfhnd(phandles[1], (long)WriteHandle);
errno = 0;
_unlock_fh(phandles[1]); /* unlock handle */
}
else {
_osfile(phandles[0]) = 0;
errno = EMFILE; /* too many files */
}
_unlock_fh(phandles[0]); /* unlock handle */
}
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;
}
return 0;
}