Kbase P50646: Named Pipes on NT example is incorrect
| Autor |
Progress Software Corporation - Progress |
| Acesso |
Público |
| Publicação |
29/10/2003 |
|
Status: Unverified
FACT(s) (Environment):
Windows NT 32 Intel/Windows 2000
FACT(s) (Environment):
Progress 9.x
SYMPTOM(s):
Named Pipes on NT example is incorrect
In the External Program Interfaces manual, the example C program for Named Pipes on Windows NT (section 4.3.5) fails to compile.
CAUSE:
Misprinted code in the manual.
FIX:
The following version of the C code works:
/* C program that reads and writes a Windows NT named pipe */
/* 1. Declare include files */
#include <windows.h>
#include <stdio.h>
#include <wincon.h>
#include <winerror.h>
#include <conio.h>
void main()
{
/* 2. Define automatic data items */
HANDLE hPipe;
char buffer[4096];
DWORD dwBytesRead;
BOOL bRet;
int iPipeType;
int iLen;
/* 3. Make window title meaningful */
/* 4. Create the named pipe */
printf("Creating Named Pipe custpipe\n");
hPipe = CreateNamedPipe("\\\\.\\pipe\\custpipe",
PIPE_ACCESS_DUPLEX,
PIPE_TYPE_BYTE | PIPE_READMODE_BYTE | PIPE_WAIT,
1,
0,
0,
NMPWAIT_USE_DEFAULT_WAIT,
NULL);
if (hPipe == INVALID_HANDLE_VALUE)
{
printf("Error creating pipe, %ld\n", GetLastError());
exit(GetLastError());
}
printf("custpipe created successfully\n");
/* 5. Solicit user input */
do
{ printf("\nPress 1 for Read, 2 for Write: ");
iPipeType = getch(); }
while (iPipeType != '1' && iPipeType != '2');
/* 6. Connect the named pipe */
printf("\nWaiting for connection...");
if (ConnectNamedPipe(hPipe, NULL) == FALSE)
{
printf("Error connecting to named pipe, %ld", GetLastError());
exit(GetLastError());
}
printf("and connection established\n");
/* 7. Read and write the pipe */
switch(iPipeType)
{
case '1': /* read */
while (TRUE)
{
bRet = ReadFile(hPipe, &buffer, 4096, &dwBytesRead, NULL);
if (bRet == FALSE)
{
/* if the pipe went away, the 4GL app did an OUTPUT CLOSE */
if (GetLastError() == ERROR_BROKEN_PIPE)
printf("Error reading from pipe, %ld\n", GetLastError());
break;
}
printf("Data read = %ld %s\n", dwBytesRead, buffer);
} /* end while */
break;
case '2': /* write */
while (TRUE)
{
printf(
"Enter data to send, followed by ENTER: (Blank to exit) \n"
);
gets(buffer);
if (buffer[0] == 0)
break;
iLen = strlen(buffer);
buffer[iLen++] = 0x0d; /* CR */
buffer[iLen++] = 0x0a; /* LF */
bRet = WriteFile(hPipe, &buffer, (DWORD) iLen, &dwBytesRead,
NULL);
if (bRet)
{
FlushFileBuffers(hPipe);
printf("%ld bytes flushed to pipe\n", dwBytesRead);
}
else
printf("Error writing to pipe: %d\n", GetLastError());
} /* end while */
break;
} /* end switch */
/* 8. Close and exit */
CloseHandle(hPipe);
printf("custpipe closed successfully\nBye");
}