16,472
社区成员
发帖
与我相关
我的任务
分享
/* PIPE.C: This program uses the _pipe function to pass streams of
* text to spawned processes.
*/
#include <stdlib.h>
#include <stdio.h>
#include <io.h>
#include <fcntl.h>
#include <process.h>
#include <math.h>
enum PIPES { READ, WRITE }; /* Constants 0 and 1 for READ and WRITE */
#define NUMPROBLEM 8
void main( int argc, char *argv[] )
{
int hpipe[2];
char hstr[20];
int pid, problem, c;
int termstat;
/* If no arguments, this is the spawning process */
if( argc == 1 )
{
setvbuf( stdout, NULL, _IONBF, 0 );
/* Open a set of pipes */
if( _pipe( hpipe, 256, O_BINARY ) == -1 )
exit( 1 );
/* Convert pipe read handle to string and pass as argument
* to spawned program. Program spawns itself (argv[0]).
*/
itoa( hpipe[READ], hstr, 10 );
if( ( pid = spawnl( P_NOWAIT, argv[0], argv[0],
hstr, NULL ) ) == -1 )
printf( "Spawn failed" );
/* Put problem in write pipe. Since spawned program is
* running simultaneously, first solutions may be done
* before last problem is given.
*/
for( problem = 1000; problem <= NUMPROBLEM * 1000; problem += 1000)
{
printf( "Son, what is the square root of %d?\n", problem );
write( hpipe[WRITE], (char *)&problem, sizeof( int ) );
}
/* Wait until spawned program is done processing. */
_cwait( &termstat, pid, WAIT_CHILD );
if( termstat & 0x0 )
printf( "Child failed\n" );
close( hpipe[READ] );
close( hpipe[WRITE] );
}
/* If there is an argument, this must be the spawned process. */
else
{
/* Convert passed string handle to integer handle. */
hpipe[READ] = atoi( argv[1] );
/* Read problem from pipe and calculate solution. */
for( c = 0; c < NUMPROBLEM; c++ )
{
read( hpipe[READ], (char *)&problem, sizeof( int ) );
printf( "Dad, the square root of %d is %3.2f.\n",
problem, sqrt( ( double )problem ) );
}
}
}
Output
Son, what is the square root of 1000?
Son, what is the square root of 2000?
Son, what is the square root of 3000?
Son, what is the square root of 4000?
Son, what is the square root of 5000?
Son, what is the square root of 6000?
Son, what is the square root of 7000?
Son, what is the square root of 8000?
Dad, the square root of 1000 is 31.62.
Dad, the square root of 2000 is 44.72.
Dad, the square root of 3000 is 54.77.
Dad, the square root of 4000 is 63.25.
Dad, the square root of 5000 is 70.71.
Dad, the square root of 6000 is 77.46.
Dad, the square root of 7000 is 83.67.
Dad, the square root of 8000 is 89.44.
Example 2
// This is a simple filter application. It will spawn
// the application on command line. But before spawning
// the application, it will create a pipe that will direct the
// spawned application's stdout to the filter. The filter
// will remove ASCII 7 (beep) characters.
// Beeper.Cpp
/* Compile options needed: None */
#include <stdio.h>
#include <string.h>
int main()
{
int i;
for(i=0;i<100;++i)
{
printf("\nThis is speaker beep number %d... \n\7", i+1);
}
return 0;
}
// BeepFilter.Cpp
/* Compile options needed: none
Execute as: BeepFilter.exe <path>Beeper.exe
*/
#include <windows.h>
#include <process.h>
#include <memory.h>
#include <string.h>
#include <stdio.h>
#include <fcntl.h>
#include <io.h>
#define OUT_BUFF_SIZE 512
#define READ_HANDLE 0
#define WRITE_HANDLE 1
#define BEEP_CHAR 7
char szBuffer[OUT_BUFF_SIZE];
int Filter(char* szBuff, ULONG nSize, int nChar)
{
char* szPos = szBuff + nSize -1;
char* szEnd = szPos;
int nRet = nSize;
while (szPos > szBuff)
{
if (*szPos == nChar)
{
memmove(szPos, szPos+1, szEnd - szPos);
--nRet;
}
--szPos;
}
return nRet;
}
int main(int argc, char** argv)
{
int nExitCode = STILL_ACTIVE;
if (argc >= 2)
{
HANDLE hProcess;
int hStdOut;
int hStdOutPipe[2];
// Create the pipe
if(_pipe(hStdOutPipe, 512, O_BINARY | O_NOINHERIT) == -1)
return 1;
// Duplicate stdout handle (next line will close original)
hStdOut = _dup(_fileno(stdout));
// Duplicate write end of pipe to stdout handle
if(_dup2(hStdOutPipe[WRITE_HANDLE], _fileno(stdout)) != 0)
return 2;
// Close original write end of pipe
close(hStdOutPipe[WRITE_HANDLE]);
// Spawn process
hProcess = (HANDLE)spawnvp(P_NOWAIT, argv[1],
(const char* const*)&argv[1]);
// Duplicate copy of original stdout back into stdout
if(_dup2(hStdOut, _fileno(stdout)) != 0)
return 3;
// Close duplicate copy of original stdout
close(hStdOut);
if(hProcess)
{
int nOutRead;
while (nExitCode == STILL_ACTIVE)
{
nOutRead = read(hStdOutPipe[READ_HANDLE],
szBuffer, OUT_BUFF_SIZE);
if(nOutRead)
{
nOutRead = Filter(szBuffer, nOutRead, BEEP_CHAR);
fwrite(szBuffer, 1, nOutRead, stdout);
}
if(!GetExitCodeProcess(hProcess,(unsigned long*)&nExitCode))
return 4;
}
}
}
printf("\nPress \'ENTER\' key to continue... ");
getchar();
return nExitCode;
}
Process and Environment Control Routines
See Also _open
SECURITY_ATTRIBUTES sa = {0};
STARTUPINFO si = {0};
PROCESS_INFORMATION pi = {0};
HANDLE hPipeOutputRead = NULL;
HANDLE hPipeOutputWrite = NULL;
HANDLE hPipeInputRead = NULL;
HANDLE hPipeInputWrite = NULL;
BOOL bTest = 0;
DWORD dwNumberOfBytesRead = 0;
CHAR szMsg[100];
CHAR szBuffer[256];
sa.nLength = sizeof(sa);
sa.bInheritHandle = TRUE;
sa.lpSecurityDescriptor = NULL;
// Create pipe for standard output redirection.
CreatePipe(&hPipeOutputRead, // read handle
&hPipeOutputWrite, // write handle
&sa, // security attributes
0 // number of bytes reserved for pipe - 0 default
);
// Create pipe for standard input redirection.
CreatePipe(&hPipeInputRead, // read handle
&hPipeInputWrite, // write handle
&sa, // security attributes
0 // number of bytes reserved for pipe - 0 default
);
// Make child process use hPipeOutputWrite as standard out,
// and make sure it does not show on screen.
si.cb = sizeof(si);
si.dwFlags = STARTF_USESHOWWINDOW | STARTF_USESTDHANDLES;
si.wShowWindow = SW_HIDE;
si.hStdInput = hPipeInputRead;
si.hStdOutput = hPipeOutputWrite;
si.hStdError = hPipeOutputWrite;
CreateProcess (
NULL, "CONSPAWN.EXE DOSAPP.EXE",
NULL, NULL,
TRUE, 0,
NULL, NULL,
&si, &pi);
// Now that handles have been inherited, close it to be safe.
// You don't want to read or write to them accidentally.
CloseHandle(hPipeOutputWrite);
CloseHandle(hPipeInputRead);
// Now test to capture DOS application output by reading
// hPipeOutputRead. Could also write to DOS application
// standard input by writing to hPipeInputWrite.
while(TRUE)
{
bTest=ReadFile(
hPipeOutputRead, // handle of the read end of our pipe
&szBuffer, // address of buffer that receives data
256, // number of bytes to read
&dwNumberOfBytesRead, // address of number of bytes read
NULL // non-overlapped.
);
if (!bTest){
wsprintf(szMsg, "Error #%d reading pipe.",GetLastError());
MessageBox(NULL, szMsg, "Test", MB_OK);
break;
}
// do something with data.
szBuffer[dwNumberOfBytesRead] = 0; // null terminate
MessageBox(NULL, szBuffer, "Test", MB_OK);
}
// Wait for CONSPAWN to finish.
WaitForSingleObject (pi.hProcess, INFINITE);
// Close all remaining handles
CloseHandle (pi.hProcess);
CloseHandle (hPipeOutputRead);
CloseHandle (hPipeInputWrite);
#pragma comment(lib,"user32")
#include <stdio.h>
#include <windows.h>
int main() {
SECURITY_ATTRIBUTES sa = {0};
STARTUPINFO si = {0};
PROCESS_INFORMATION pi = {0};
HANDLE hPipeOutputRead = NULL;
HANDLE hPipeOutputWrite = NULL;
HANDLE hPipeInputRead = NULL;
HANDLE hPipeInputWrite = NULL;
BOOL bTest = 0;
DWORD dwNumberOfBytesRead = 0;
DWORD dwNumberOfBytesWrite = 0;
CHAR szMsg[100];
CHAR szBuffer[256];
sa.nLength = sizeof(sa);
sa.bInheritHandle = TRUE;
sa.lpSecurityDescriptor = NULL;
// Create pipe for standard output redirection.
CreatePipe(&hPipeOutputRead, // read handle
&hPipeOutputWrite, // write handle
&sa, // security attributes
0 // number of bytes reserved for pipe - 0 default
);
// Create pipe for standard input redirection.
CreatePipe(&hPipeInputRead, // read handle
&hPipeInputWrite, // write handle
&sa, // security attributes
0 // number of bytes reserved for pipe - 0 default
);
// Make child process use hPipeOutputWrite as standard out,
// and make sure it does not show on screen.
si.cb = sizeof(si);
si.dwFlags = STARTF_USESHOWWINDOW | STARTF_USESTDHANDLES;
si.wShowWindow = SW_HIDE;
si.hStdInput = hPipeInputRead;
si.hStdOutput = hPipeOutputWrite;
si.hStdError = hPipeOutputWrite;
CreateProcess (
NULL, "cmd.exe",
NULL, NULL,
TRUE, 0,
NULL, NULL,
&si, &pi);
// Now that handles have been inherited, close it to be safe.
// You don't want to read or write to them accidentally.
CloseHandle(hPipeOutputWrite);
CloseHandle(hPipeInputRead);
// Now test to capture DOS application output by reading
// hPipeOutputRead. Could also write to DOS application
// standard input by writing to hPipeInputWrite.
sprintf(szMsg, "dir *.txt /b\nexit\n");
WriteFile(
hPipeInputWrite, // handle of the write end of our pipe
&szMsg, // address of buffer that send data
18, // number of bytes to write
&dwNumberOfBytesWrite,// address of number of bytes read
NULL // non-overlapped.
);
while(TRUE)
{
bTest=ReadFile(
hPipeOutputRead, // handle of the read end of our pipe
&szBuffer, // address of buffer that receives data
256, // number of bytes to read
&dwNumberOfBytesRead, // address of number of bytes read
NULL // non-overlapped.
);
if (!bTest){
sprintf(szMsg, "Error #%d reading pipe.",GetLastError());
MessageBox(NULL, szMsg, "WinPipe", MB_OK);
break;
}
// do something with data.
szBuffer[dwNumberOfBytesRead] = 0; // null terminate
MessageBox(NULL, szBuffer, "WinPipe", MB_OK);
}
// Wait for CONSPAWN to finish.
WaitForSingleObject (pi.hProcess, INFINITE);
// Close all remaining handles
CloseHandle (pi.hProcess);
CloseHandle (hPipeOutputRead);
CloseHandle (hPipeInputWrite);
return 0;
}