I have my main application ,from my main application I will be calling another
module(third party) to perform a small operation in my main application,when I call that module..it processes for a particular time say 5 sec.while its proccessing it shows the process in the commmand window with some information..now my main application waits until the called module finishes its process.Now my Question is..how to do I hide this command window without disturbing its process..I tried to use the createprocess but it seems to not work...
for example: my main application is the Parent process and the called application is child process..Parent process should be independent of the child process..check my example below
int main()
{
execl("c:\\users\\rakesh\\Desktop\\calledapplication.exe","c:\\users\\rakesh\\Desktop \\calledapplication.exe",0);
}
code in calledapplication
int main
{
printf("Rakesh");
}
now considering the above if you run the first program...output would appear in the same
command window(It shouldnt be like that)...I want the main application to create the process but it should not be affected by child process.
Pass CREATE_NO_WINDOW in the dwCreationFlags parameter of CreateProcess.
You talked about a "command window", so I presume that the child is a console application.
In that case you can create the process in a separate conole and optionally force the new console to be iconified or hidden.
The following code launch a child process that interprets a batch file (mytest.bat).
I hope it can help. Regards.
#include <windows.h>
#include <stdio.h>
int main(int argc, char **argv)
{
STARTUPINFO si;
PROCESS_INFORMATION pi;
BOOL rv = FALSE;
WCHAR cmdline[] = TEXT("cmd.exe /c mytest.bat");
memset(&si,0,sizeof(si));
si.cb = sizeof(si);
// Add this if you want to hide or minimize the console
si.dwFlags = STARTF_USESHOWWINDOW;
si.wShowWindow = SW_HIDE; //or SW_MINIMIZE
///////////////////////////////////////////////////////
memset(&pi,0,sizeof(pi));
rv = CreateProcess(NULL, cmdline, NULL, NULL,
FALSE, CREATE_NEW_CONSOLE,
NULL, NULL, &si, &pi);
if (rv) {
WaitForSingleObject(pi.hProcess, INFINITE);
printf("Done! :)\n");
}
else {
printf("Failed :(\n");
}
return rv ? 0 : 1;
}
It sounds like you want the child process's output to show up in a separate window. If so, you want to call CreateProcess and pass it the CREATE_NEW_CONSOLE flag, rather than using exec*.
Related
I use c system() function in my application to launch commands like these:
cmd.exe /c a.bat
guiapp.exe
consoleapp.exe
It works, however, system() launches guiapp.exe with console displayed (which, obviously, is not used in this gui app). How to launch new process considering the fact that I don't know whether process to be launched should display console? I want to launch the process in the same way as the process would be launched when double clicked by mouse.
You can use CreateProcess and in the dwFlags parameter do not specify CREATE_NEW_CONSOLE as one of the flags.
This way, if the application is a GUI app, it will not launch a console window, and if it is a console app, it will run in the same console as the launching process.
Example code:
#include <Windows.h>
#include <stdio.h>
int main(void)
{
PROCESS_INFORMATION pi, pi2;
STARTUPINFO si, si2;
ZeroMemory(&pi, sizeof(PROCESS_INFORMATION));
ZeroMemory(&si, sizeof(STARTUPINFO));
si.cb = sizeof(STARTUPINFO);
CreateProcessW(L"C:\\GUIAppDir\\GUIApp.exe", L"program-arguments-here", NULL, NULL, FALSE, CREATE_UNICODE_ENVIRONMENT, NULL, L"C:\\GUIAppDir", &si, &pi);
ZeroMemory(&pi2, sizeof(PROCESS_INFORMATION));
ZeroMemory(&si2, sizeof(STARTUPINFO));
si2.cb = sizeof(STARTUPINFO);
CreateProcessW(L"C:\\ConsoleAppDir\\ConsoleApp.exe", L"program-arguments-here", NULL, NULL, FALSE, CREATE_UNICODE_ENVIRONMENT, NULL, L"C:\\ConsoleAppDir", &si2, &pi2);
WaitForSingleObject(pi2.hProcess, INFINITE);
CloseHandle(pi2.hThread);
CloseHandle(pi2.hProcess);
WaitForSingleObject(pi.hProcess, INFINITE);
CloseHandle(pi.hThread);
CloseHandle(pi.hProcess);
return 0;
}
Is it possible to wait for all processes launched by a child process in Windows? I can't modify the child or grandchild processes.
Specifically, here's what I want to do. My process launches uninstallA.exe. The process uninistallA.exe launches uninstallB.exe and immediately exits, and uninstallB.exe runs for a while. I'd like to wait for uninstallB.exe to exit so that I can know when the uninstall is finished.
Create a Job Object with CreateJobObject. Use CreateProcess to start UninstallA.exe in a suspended state. Assign that new process to your job object with AssignProcessToJobObject. Start UninstallA.exe running by calling ResumeThread on the handle of the thread you got back from CreateProcess.
Then the hard part: wait for the job object to complete its execution. Unfortunately, this is quite a bit more complex than anybody would reasonably hope for. The basic idea is that you create an I/O completion port, then you create the object object, associate it with the I/O completion port, and finally wait on the I/O completion port (getting its status with GetQueuedCompletionStatus). Raymond Chen has a demonstration (and explanation of how this came about) on his blog.
Here's a technique that, while not infallible, can be useful if for some reason you can't use a job object. The idea is to create an anonymous pipe and let the child process inherit the handle to the write end of the pipe.
Typically, grandchild processes will also inherit the write end of the pipe. In particular, processes launched by cmd.exe (e.g., from a batch file) will inherit handles.
Once the child process has exited, the parent process closes its handle to the write end of the pipe, and then attempts to read from the pipe. Since nobody is writing to the pipe, the read operation will block indefinitely. (Of course you can use threads or asynchronous I/O if you want to keep doing stuff while waiting for the grandchildren.)
When (and only when) the last handle to the write end of the pipe is closed, the write end of the pipe is automatically destroyed. This breaks the pipe and the read operation completes and reports an ERROR_BROKEN_PIPE failure.
I've been using this code (and earlier versions of the same code) in production for a number of years.
// pwatch.c
//
// Written in 2011 by Harry Johnston, University of Waikato, New Zealand.
// This code has been placed in the public domain. It may be freely
// used, modified, and distributed. However it is provided with no
// warranty, either express or implied.
//
// Launches a process with an inherited pipe handle,
// and doesn't exit until (a) the process has exited
// and (b) all instances of the pipe handle have been closed.
//
// This effectively waits for any child processes to exit,
// PROVIDED the child processes were created with handle
// inheritance enabled. This is usually but not always
// true.
//
// In particular if you launch a command shell (cmd.exe)
// any commands launched from that command shell will be
// waited on.
#include <windows.h>
#include <stdio.h>
void error(const wchar_t * message, DWORD err) {
wchar_t msg[512];
swprintf_s(msg, sizeof(msg)/sizeof(*msg), message, err);
printf("pwatch: %ws\n", msg);
MessageBox(NULL, msg, L"Error in pwatch utility", MB_OK | MB_ICONEXCLAMATION | MB_SYSTEMMODAL);
ExitProcess(err);
}
int main(int argc, char ** argv) {
LPWSTR lpCmdLine = GetCommandLine();
wchar_t ch;
DWORD dw, returncode;
HANDLE piperead, pipewrite;
STARTUPINFO si;
PROCESS_INFORMATION pi;
SECURITY_ATTRIBUTES sa;
char buffer[1];
while (ch = *(lpCmdLine++)) {
if (ch == '"') while (ch = *(lpCmdLine++)) if (ch == '"') break;
if (ch == ' ') break;
}
while (*lpCmdLine == ' ') lpCmdLine++;
sa.nLength = sizeof(sa);
sa.bInheritHandle = TRUE;
sa.lpSecurityDescriptor = NULL;
if (!CreatePipe(&piperead, &pipewrite, &sa, 1)) error(L"Unable to create pipes: %u", GetLastError());
GetStartupInfo(&si);
if (!CreateProcess(NULL, lpCmdLine, NULL, NULL, TRUE, 0, NULL, NULL, &si, &pi))
error(L"Error %u creating process.", GetLastError());
if (WaitForSingleObject(pi.hProcess, INFINITE) == WAIT_FAILED) error(L"Error %u waiting for process.", GetLastError());
if (!GetExitCodeProcess(pi.hProcess, &returncode)) error(L"Error %u getting exit code.", GetLastError());
CloseHandle(pipewrite);
if (ReadFile(piperead, buffer, 1, &dw, NULL)) {
error(L"Unexpected data received from pipe; bug in application being watched?", ERROR_INVALID_HANDLE);
}
dw = GetLastError();
if (dw != ERROR_BROKEN_PIPE) error(L"Unexpected error %u reading from pipe.", dw);
return returncode;
}
There is not a generic way to wait for all grandchildren but for your specific case you may be able to hack something together. You know you are looking for a specific process instance. I would first wait for uninstallA.exe to exit (using WaitForSingleObject) because at that point you know that uninstallB.exe has been started. Then use EnumProcesses and GetProcessImageFileName from PSAPI to find the running uninstallB.exe instance. If you don't find it you know it has already finished, otherwise you can wait for it.
An additional complication is that if you need to support versions of Windows older than XP you can't use GetProcessImageFileName, and for Windows NT you can't use PSAPI at all. For Windows 2000 you can use GetModuleFileNameEx but it has some caveats that mean it might fail sometimes (check docs). If you have to support NT then look up Toolhelp32.
Yes this is super ugly.
Use a named mutex.
One possibility is to install Cygwin and then use the ps command to watch for the grandchild to exit
Hi I'm creating more than one process with the CreateProcess
and I need to wait all of them to finish, to analyze the results.
And I cant WaitForSingleObject because I need all of the processes running at the same time.
Since each process has a handle at Process_Information (hProcess)
I tought it was ok to use WaitForMultipleObjects,but the parent process ends without waiting for the child.
Is it ok to use WaitForMultipleObjects or there is a better way?
This is how I'm creating the processes:
#define MAX_PROCESS 3
STARTUPINFO si[MAX_PROCESS];
PROCESS_INFORMATION pi[MAX_PROCESS];
WIN32_FIND_DATA fileData;
HANDLE find;
int j=0, t=0;
ZeroMemory(&si, sizeof(si));
for (t = 0; t < MAX_PROCESS; t++)
si[t].cb = sizeof(si[0]);
ZeroMemory(&pi, sizeof(pi));
while (FindNextFile(find, &fileData) != 0)
{
// Start the child process.
if (!CreateProcess(_T("C:\\Users\\Kumppler\\Documents\\Visual Studio 2010\\Projects\ \teste3\\Debug\\teste3.exe"), // No module name (use command line)
aux2, // Command line
NULL, // Process handle not inheritable
NULL, // Thread handle not inheritable
TRUE, // Set handle inheritance to FALSE
0, // No creation flags
NULL, // Use parent's environment block
NULL, // Use parent's starting directory
&si[j], // Pointer to STARTUPINFO structure
&pi[j]) // Pointer to PROCESS_INFORMATION structure
)
{
printf("CreateProcess failed (%d).\n", GetLastError());
return;
}
j++;
//find next file related
}
FindClose(find);
WaitForMultipleObjects(MAX_PROCESS, &pi[j].hProcess, FALSE, INFINITE);
//wait and analyze results
Btw I'm trying not to use threads.
WaitForMultipleObjects expects array of handles:
HANDLE hanldes[MAX_PROCESS];
for (int i = 0; i < MAX_PROCESS; ++i)
{
handles[i] = pi[i].hProcess;
}
WaitForMultipleObjects(MAX_PROCESS, handles, TRUE, INFINITE);
Also you should know that maximum array size of handles for WaitForMultipleObjects is limited to MAXIMUM_WAIT_OBJECTS (which is 64).
If you want to wait for all the HANDLEs set 'bWaitAll' (the third parameter) to 'TRUE'.
I want to kick off a process (we'll use notepad for simplicity) without the console window popping up.
I'm sure I've missed something very simple, here is my most simplified test case:
#include <windows.h>
#include <stdio.h>
#include <tchar.h>
void _tmain( int argc, TCHAR *argv[] )
{
STARTUPINFO si;
PROCESS_INFORMATION pi;
ZeroMemory( &si, sizeof(si) );
si.cb = sizeof(si);
ZeroMemory( &pi, sizeof(pi) );
// Start the child process.
if( !CreateProcess( NULL, // No module name (use command line)
"notepad", // Command line
NULL, // Process handle not inheritable
NULL, // Thread handle not inheritable
FALSE, // Set handle inheritance to FALSE
CREATE_NO_WINDOW, // No creation flags
NULL, // Use parent's environment block
NULL, // Use parent's starting directory
&si, // Pointer to STARTUPINFO structure
&pi ) // Pointer to PROCESS_INFORMATION structure
)
{
printf( "CreateProcess failed (%d).\n", GetLastError() );
return;
}
// Wait until child process exits.
WaitForSingleObject( pi.hProcess, INFINITE );
// Close process and thread handles.
CloseHandle( pi.hProcess );
CloseHandle( pi.hThread );
}
You are creating a new process(notepad.exe) from a parent process(your console application), and let parent process wait for child process to finish. The console window is the main window of your parent process. You can hide and restore is as show below.
// Notice how hiding the console window causes it to disappear from
// the Windows task bar. If you only want to make it minimize, use
// SW_MINIMIZE instead of SW_HIDE.
void _tmain(int argc, TCHAR *argv[])
{
ShowWindow( GetConsoleWindow(), SW_HIDE );
// create a new process and wait for it to finish
ShowWindow( GetConsoleWindow(), SW_RESTORE );
}
Change the application subsystem from Console to Windows. In VS2008, this is under linker properties, System.
Then change your main function to:
int APIENTRY _tWinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPTSTR lpCmdLine, int nCmdShow)
and change the code to return an int.
This is how you change the application subsystem from Console to Windows using MinGW, add these linker flags:
-Wl,-subsystem,windows
I am using CreateProcess to create a cmd.exe process that is passed a parameter that it executes and quits, this makes command prompt flash up on the screen.
I tried to avoid this by setting STARTUPINFO struct wShowWindow to SW_HIDE but this parameter seems to affect the calling window, not the window for the process that gets executed.
Is there anyway that you can use createprocess to launch a program that is hidden from view?
Also what is the proper winapi standard way to get enviroment variables?
If its just a console app you can also use the CREATE_NO_WINDOW flag as part of the CreateProcess call itself, e.g.
CreateProcess(NULL, lpszCommandLine, NULL, NULL, FALSE,
CREATE_NO_WINDOW, NULL, NULL, &si, &pi);
Also, see this page for information about environment variables.
The following link here describes how to create the window silently:
DWORD RunSilent(char* strFunct, char* strstrParams)
{
STARTUPINFO StartupInfo;
PROCESS_INFORMATION ProcessInfo;
char Args[4096];
char *pEnvCMD = NULL;
char *pDefaultCMD = "CMD.EXE";
ULONG rc;
memset(&StartupInfo, 0, sizeof(StartupInfo));
StartupInfo.cb = sizeof(STARTUPINFO);
StartupInfo.dwFlags = STARTF_USESHOWWINDOW;
StartupInfo.wShowWindow = SW_HIDE;
Args[0] = 0;
pEnvCMD = getenv("COMSPEC");
if(pEnvCMD){
strcpy(Args, pEnvCMD);
}
else{
strcpy(Args, pDefaultCMD);
}
// "/c" option - Do the command then terminate the command window
strcat(Args, " /c ");
//the application you would like to run from the command window
strcat(Args, strFunct);
strcat(Args, " ");
//the parameters passed to the application being run from the command window.
strcat(Args, strstrParams);
if (!CreateProcess( NULL, Args, NULL, NULL, FALSE,
CREATE_NEW_CONSOLE,
NULL,
NULL,
&StartupInfo,
&ProcessInfo))
{
return GetLastError();
}
WaitForSingleObject(ProcessInfo.hProcess, INFINITE);
if(!GetExitCodeProcess(ProcessInfo.hProcess, &rc))
rc = 0;
CloseHandle(ProcessInfo.hThread);
CloseHandle(ProcessInfo.hProcess);
return rc;
}
I think getenv and setenv are all okay? I am not sure what you are asking about in that respect.
set the STARTF_USESHOWWINDOW in dwFlags
by sharptooth
This might be an overkill for your needs, but you can hook the ShowWindow API and never show any windows for that process