Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 6 years ago.
Improve this question
I have a program which crashs sometimes. On such occasion my program should restart itself. But while killing it through Task Manager it should end.
I have create Monitor program which monitors actual program and restart it on crash.
I have do this job using signals that are sent the actual program to terminate it.
I am using Windows OS.
That is I need to intercept the signal sent to actual program in my monitor program
A process monitor should do the following:
Create the main process, and thereby obtain a handle to that process.
Wait for that handle to become signaled, for instance with WaitForSingleObject, which indicates that the process has terminated.
Restart the process, obtaining a new process handle, and then go to 2.
You should arrange that the monitor program always creates the main process and that both are in a job object that is configured for child processes to be terminated when the parent terminates. Then when you wish to terminate the program, you simply terminate the monitor. The job object then ensures that the child program is also terminated.
If possible though, you should fix your program so that it does not crash.
Let's ignore your question for a moment, and address the problem instead. You are looking for a way to restart your application on abnormal exit, but still retain the ability, to terminate the application (either through its GUI or Task Manager).
Windows offers Application Recovery and Restart for this. It is the infrastructure built into the system, that allows you to register an application for restart in case of an unhandled exception (informally called a crash).
of course you need fix your app, for it not crashed. only this is good solution. however formally you can do next (bad)
void Ep()
{
// tag by * in begin of CommandLine
PWSTR CommandLine = GetCommandLine();
if (!CommandLine || *CommandLine != '*')
{
// monitor case
WCHAR FileName[MAX_PATH];
if (ULONG n = GetModuleFileName(0, FileName, RTL_NUMBER_OF(FileName)))
{
if (n < MAX_PATH)
{
PROCESS_INFORMATION pi;
STARTUPINFO si = { sizeof(si) };
PWSTR newCommandLine = (PWSTR)alloca((wcslen(CommandLine) + 2)*sizeof(WCHAR));
*newCommandLine = '*';
wcscpy(newCommandLine + 1, CommandLine);
// monitor and restart self in loop
BOOL bRestart;
do
{
bRestart = FALSE;
if (CreateProcessW(FileName, newCommandLine, 0, 0, 0, 0, 0, 0, &si, &pi))
{
CloseHandle(pi.hThread);
WaitForSingleObject(pi.hProcess, INFINITE);
ULONG exitcode;
bRestart = GetExitCodeProcess(pi.hProcess, &exitcode);
CloseHandle(pi.hProcess);
if (bRestart)
{
// 0xff - terminated by WerFault
// (int)exitcode < 0 - exception in process
bRestart = exitcode == 0xff || ((int)exitcode < 0);
}
}
} while (bRestart);
}
}
ExitProcess(0);
}
else
{
// main case
wcscpy(CommandLine, CommandLine + 1);
if (MessageBoxW(0, L"make crash ?", CommandLine, MB_YESNO) == IDYES)
{
__debugbreak();// simulate crash
}
ExitProcess(0);
}
}
Related
My application runs particular number of processes(different executables) using createprocess(windows api) in parallel(using threads). User can refresh / close my application at any time. As of now, I am pushing the process handles into vector and whenever close request received, I am iterating the vector and terminating(using GetExitCodeProcess and TerminateProcess APIs) and closing(using CloseHandle API) the process handles. Also I am closing the handle of the process when it is completed. The problem with current model is, whenever process completed handle will be closed and when close request received again I will try to close it using vector(handle is not updated). To solve this, I have to update/remove the handle in/from the vector. To do this, need to maintain index.
Since I know the number of process, I want to create a static vector and update it rather than pushing a local object to a vector. Can someone suggest a best approach.
Below is the sample code.
//member object
std::vector<PROCESS_INFORMATION> mProcessHandles;
//this is a thread and will be called multiple times with different executable names in the application
void method(std::string executable)
{
STARTUPINFO startInfo{};
PROCESS_INFORMATION procInfo{};
bool ret = CreateProcess(NULL, executable, NULL, NULL, TRUE, CREATE_NO_WINDOW, NULL, NULL, &startInfo, &procInfo);
mProcessInfo.push_back(procInfo);
if(ret)
{
WaitForSingleObject(procInfo.hProcess, INFINITE);
CloseHandle(procInfo.hProcess);
procInfo.hProcess = NULL;
CloseHandle(procInfo.hThread);
procInfo.hThread = NULL;
}
return;
}
//this will be called when application close requested
void forceKill()
{
for (auto &processHandlesIt : mProcessHandles)
{
DWORD errorcode = 0;
GetExitCodeProcess(processHandlesIt.hProcess, &errorcode);
if (errorcode == STILL_ACTIVE)
{
TerminateProcess(processHandlesIt.hProcess, errorcode);
}
CloseHandle(processHandlesIt.hProcess);
processHandlesIt.hProcess = NULL;
CloseHandle(processHandlesIt.hThread);
processHandlesIt.hThread = NULL;
}
}
You should not use handles (in GetExitCodeProcess for example) after they are closed.
I would simply not close those process handles in the threads, and just leave them for the forceKill or other clean-up function to close.
Also, since you are not using procInfo.hThread, you could close it right after CreateProcess returns.
I guess you are not using any other members of the procInfo, so you could only store the process' handles in your vector.
I'm creating a Windows Add/Remove Programs application in Qt 5.4 and I'm becaming crazy to solve a little "puzzle":
My application (APP_0) runs another application (APP_1) and waits for this APP_1 until it terminates.
APP_1 is an uninstaller (i.e. uninstall.exe) and I've not the source code of the APP_1, just of my Qt APP_0.
APP_1, instead of doing the uninstall job, it simply copies itself somewhere in the filesystem (I saw as Au_.exe but other apps could use different names and locations), runs this copy of itself (APP_2) and terminates.
The APP_2 has a GUI and the job I'm waiting for (uninstall) is demanded to the final user of the running APP_2.
In this situation my application (APP_0) stops waiting for APP_1 pratically immediately (because it launches APP_1 and waits for APP_1). But to work properly, obviously, I need to know instead when APP_2 is terminated...
So the question is:
is there a way (using some techniques (hooking?)) to know if and when APP_2 terminates?
Note: Consider that the standard Windows Add/Remove Programs utility does the job successfully (it seems it waits for APP_2). You can test this, for example, installing Adobe Digital Edition. Its uninstaller (uninstall.exe) copies itself into a new folder in the User_Local_Temp folder as Au_.exe, runs it and terminates. But the OS utility successfully waits for Au_.exe and only after it terminates refreshes the list of installed programs.
If this kind of technique (uninstall.exe copies itself somewhere ALWAYS with THE SAME name (Au_.exe) ) the problem could be resolved, obviously, very simply. But I don't think that the name of the copied uninstaller is always the same and also I don't like to assume things I'm not sure are real.
Many thanks in advance
Thanks to IInspectable's suggestion (see his comment... and many thanks guy!) I created a function which solves my problems! I'll share here this function which could be useful to other people with the same (or similar) problem.
For my needs, the function receives as parameter the index of the item to be uninstalled (from a QList) and gets the uninstall string (for example: C:\ProgramFiles\MyApp\uninstall.exe).
Then with this uninstall string, I'll create a process (CreateProcess) and put its handle into a Job Object, so that my function will wait for all the processes ran by this process.
The function itself is pretty simple and can be improved.
Notice that the process MUST be created with the CREATE_BREAKAWAY_FROM_JOB option, otherwise the AssignProcessToJobObject will fail with a "Access Denied" error.
void MainWindow::uniButtonClick(int idx)
{
QMessageBox::StandardButton reply;
QMessageBox::StandardButton err;
reply = QMessageBox::question(this, "Uninstall/Change", "Uninstall " +
ip[idx].displayName +"?\r\n\r\n" + ip[idx].uninstallString,
QMessageBox::Yes|QMessageBox::No);
if (reply == QMessageBox::Yes)
{
//QString s = "C:\\windows\\notepad.exe"; // Just to test Job assignment and createprocess
QString s = ip[idx].uninstallString; // the real uninstaller string
QString jobName = "MyJobObject";
try
{
PROCESS_INFORMATION ProcessInfo; //This is what we get as an [out] parameter
STARTUPINFO StartupInfo; //This is an [in] parameter
PJOBOBJECT_BASIC_PROCESS_ID_LIST pList;
HANDLE hProcess;
BOOL bJobAllEnd;
ZeroMemory(&StartupInfo, sizeof(StartupInfo));
StartupInfo.cb = sizeof StartupInfo ; //Only compulsory field
wchar_t* path;
path = (wchar_t*) malloc (sizeof(wchar_t)*s.length()+1);
s.toWCharArray(path);
path[s.length()]=0; // Null terminate the string
// Create the process with CREATE_BREAKAWAY_FROM_JOB to overcome the AccessDenied issue on AssignProcessToJobObject.
if(CreateProcess(NULL, path, NULL, NULL, FALSE, CREATE_BREAKAWAY_FROM_JOB|CREATE_SUSPENDED, NULL, NULL,&StartupInfo, &ProcessInfo))
{
pList = (PJOBOBJECT_BASIC_PROCESS_ID_LIST)GlobalAlloc(GMEM_FIXED, 10000);
HANDLE jobObj = CreateJobObject(NULL, (const wchar_t*)jobName.utf16());
if (AssignProcessToJobObject(jobObj, ProcessInfo.hProcess) != 0)
{
ResumeThread(ProcessInfo.hThread); // Process assigned to JobObjext, resume it now
do
{
QueryInformationJobObject(jobObj, JobObjectBasicProcessIdList, pList, 10000, NULL);
bJobAllEnd = TRUE;
for(DWORD i=0; i<pList->NumberOfProcessIdsInList; i++)
{
hProcess = OpenProcess(SYNCHRONIZE, FALSE, pList->ProcessIdList[i]);
if(hProcess != NULL)
{
CloseHandle(hProcess);
bJobAllEnd = FALSE;
}
}
Sleep(500);
} while(!bJobAllEnd);
}
else
qDebug() << "AssignProcess to Job failed: error = " << QString::number(GetLastError());
GlobalFree(pList);
CloseHandle(jobObj);
CloseHandle(ProcessInfo.hThread);
CloseHandle(ProcessInfo.hProcess);
}
}
catch(QString error)
{
QMessageBox::critical(this, "File not found!", "The requested uninstaller doesn't exists", QMessageBox::Ok);
}
// refresh list
handleButton();
}
}
I want to close a handle to a mutex located in another process, so I can run more than one instance of the application.
I already know this can be done, see Process Explorer. Example: Windows Minesweeper (Windows 7) uses a mutex to only allow one game, so I thought I would use it as an example since it's pre-installed with Windows and therefore easier for you guys to guide me.
The mutex that I need to close is \Sessions\1\BaseNamedObjects\Oberon_Minesweeper_Singleton, which I found using Process Explorer.
After closing this mutex I was able to launch two games of Minesweeper, but I want to do this in my program using C++.
After some searching I have found that I might need the API DuplicateHandle. So far I haven't been able to close the handle on this mutex.
Here is my code so far:
#include <Windows.h>
#include <iostream>
using namespace std;
void printerror(LPSTR location){
printf("Error: %s_%d", location, GetLastError());
cin.get();
}
int main(){
DWORD pid = 0;
HWND hMineWnd = FindWindow("Minesweeper", "Minesveiper");
GetWindowThreadProcessId(hMineWnd, &pid);
HANDLE hProc =OpenProcess(PROCESS_DUP_HANDLE, 0, pid);
if(hProc == NULL){
printerror("1");
return 1;
}
HANDLE hMutex = OpenMutex(MUTEX_ALL_ACCESS, TRUE, "Oberon_Minesweeper_Singleton");
if(hMutex == NULL){
printerror("2");
return 2;
}
if(DuplicateHandle(hProc, hMutex, NULL, 0, 0, FALSE, DUPLICATE_CLOSE_SOURCE) == 0){
printerror("3");
return 3;
}
if(CloseHandle(hMutex) == 0){
printerror("4");
return 4;
}
return 0;
}
This code returns 0, but the mutex is still there, and I am not able to launch more games of Minesweeper. I think some of my parameters to DuplicateHandle are wrong.
The second argument to DuplicateHandle expects "an open object handle that is valid in the context of the source process", however I believe the handle you're passing in would only be valid within the current process (OpenMutex creates a new handle to an existing mutex object). You'll likely need to determine what the mutex's handle is in the remote process, and use that value when calling DuplicateHandle.
i have a code like this...
c = fork();
if(c==0) {
close(fd[READ]);
if (dup2(fd[WRITE],STDOUT_FILENO) != -1)
execlp("ssh", "ssh", host, "ls" , NULL);
_exit(1);
}
close(fd[WRITE]);
fd[READ] and fd[WRITE] are pipe file descriptors.
when i run it continuously, there are a lot of zombie processes when i use ps ax. How to rectify this? Is this because i am not using the parent to wait for the exit status of the child process...
If you have no intention to wait for your child processes, set the SIGCHLD handler to SIG_IGN to have the kernel automatically reap your children, eg.
signal(SIGCHLD, SIG_IGN);
Yes, the parent must wait for the child return status. You can do it asynchronously by catching SIGCHILD in the parent process and then call waitpid in the capture method.
Yes, waitpid() should be called from parent. waitpid() will clean-up any child process of the parent process, which is currently in terminated state.
You can add below code to your program :
if(c>0)
{
while(1){
ret = waitpid(-1,&status,0);
if(ret>0){
if(WIFEXITED(status)){
if(WEXITSTATUS(status) == 0){
printf("child process terminated normally and successfully\n");
}
else{
printf("child process terminated normally and unsuccessfully\n");
}
}
else{
printf("child process terminated abnormally and unsuccessfully\n");
}
}
if(ret<0) {
break;
}
}
}
FYI : more on waitpid.
First parameter is set to -1 such that waitpid() will clean-up any child process of this parent process, which is currently in terminated state.The first parameter can also be +ve - in this case, waitpid() will cleanup only the specific child process.Most common use is to set first parameter to -1 also refer to manual page of waitpid().
Second parameter is used to extract the termination/exit status code of the child process - waitpid() system call API fills the status field when the system call API is invoked.
Last field is the flags field - currently unused - in most cases, flags field will be set to 0 - meaning, default behaviour of the system call API !!! if you really need to use flags, refer to manual page of waitpid().
Note:
In the code you submitted, _exit(1) will be called iff execlp() fails. so you can put a condition for execlp() fail and that condition _exit() can be called. The Reason is, execlp() functions only return if an error has occurred.
Modified code can be like below :
c = fork();
if(c==0) {
close(fd[READ]);
if (dup2(fd[WRITE],STDOUT_FILENO) != -1)
ret_execlp = execlp("ssh", "ssh", host, "ls" , NULL);
if(ret_execlp == -1 ) {
printf("execlp is failed");
_exit(1);
}
}
close(fd[WRITE]);
I appreciate the above 2 answers. Wish this answer may give more clarity. Thank you.
How can you find out if an executable is running on Windows given the process name, e.g. program.exe?
The C++ standard library has no such support. You need an operating system API to do this. If this is Windows then you'd use CreateToolhelp32Snapshot(), followed by Process32First and Process32Next to iterate the running processes. Beware of the inevitable race condition, the process could have exited by the time you found it.
I just created one using Hans suggestion. Works like a champ!
Oh and here is the basic code.
Please you will have to add CStrings sAppPath and sAppName.
StartProcess is a small function that uses CreateProcess and returns the PID(not used here). You will need to replace it.
This is not a complete program, just the code to find if the program is running using Hans suggestion. A fun test is to set the path to c:\windows\ and the app to notepad.exe and set it for 10 seconds.
#include <tlhelp32.h>
PROCESSENTRY32 pe32 = {0};
HANDLE hSnap;
int iDone;
int iTime = 60;
bool bProcessFound;
while(true) // go forever
{
hSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS,0);
pe32.dwSize = sizeof(PROCESSENTRY32);
Process32First(hSnap,&pe32); // Can throw away, never an actual app
bProcessFound = false; //init values
iDone = 1;
while(iDone) // go until out of Processes
{
iDone = Process32Next(hSnap,&pe32);
if (strcmp(pe32.szExeFile,sAppName) == 0) // Did we find our process?
{
bProcessFound = true;
iDone = 0;
}
}
if(!bProcessFound) // if we didn't find it running...
{
startProcess(sAppPath+sAppName,""); // start it
}
Sleep(iTime*1000); // delay x amount of seconds.
}
Assumptions: since you mention '.exe', you want this for some flavor of Windows. You want to write a program in C++ to determine whether a program with a particular executable name is running (regardless of the language used to implement the target program).
Enumerate the running processes using either the Toolhelp API or the process status API. Compare the name of the executable for each running process to the one you're looking for (and be aware that there may be more than one process with that executable name).
hProcessInfo = OpenProcess( PROCESS_ALL_ACCESS, FALSE, pe32.th32ProcessID );
do{
if(strcmp(pe32.szExeFile,"process.exe") == 0)
{
processfound = true;
break;
}
}while( Process32Next( hProcessSnap, &pe32 ) );
If you don't want to get process detail from code just press Ctrl+Alt+Del and check process list.