So, curious problem, I'm trying to create a process, and then resume it, mostly exploring the Windows API. I've noticed that if I do this:
system("C:\\Windows\\System32\\calc.exe");
It will open a calculator exe, however if I try to do the same thing using CreateProcessA, I get this:
STARTUPINFO starting_info;
PROCESS_INFORMATION process_info;
// let's try and make a process
if (!CreateProcessA(NULL, "C:\\Windows\\System32\\calc.exe", NULL, NULL, FALSE, CREATE_SUSPENDED, NULL, NULL, &starting_info, &process_info)) {
return;
}
// resume thread
NtResumeThread(process_info.hThread, NULL);
This for some reason throws an error of 0xc0000142 most of the times when it "creates" the process, else it just fails.
What's going on?
See the following MSDN sample code for creating a process:
https://msdn.microsoft.com/en-us/library/windows/desktop/ms682512(v=vs.85).aspx
You need to zero out the si and pi structs, also set
si.cb = sizeof(si);
In the end, close process and thread handles.
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
Related
The Command CreateProcess With the command WaitForSingleObject
can to open an image?
If Yes How can I open the image?
I tried to open but i don't know Where to put the path to open
if (CreateProcess(NULL, "C:\ProgramData\Microsoft\Windows\Start Menu\Programs\Accessories\Paint.lnk", NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi))
{
WaitForSingleObject(pi.hProcess, INFINITE);
CloseHandle(pi.hThread);
CloseHandle(pi.hProcess);
}
If you just want to open an existing image using defualt app then use ShellExectue API. For example:
ShellExecuteW(NULL, L"open", L"Z:\\cat.PNG", NULL, NULL, SW_SHOW);
You could also open image with mspaint using the same API:
ShellExecuteW(NULL, L"open", L"C:\\Windows\\system32\\mspaint.exe", L"Z:\\cat.PNG", NULL, SW_SHOW);
ShellExecuteEx will let you wait for finishing process.
You can do the same using CreateProcess. As #DavidHeffernan pointed out the second parameter of CreateProcess should point to writable memory else it will raise access violation. To make it clear I will just omit the first parameter. Example:
STARTUPINFOW process_startup_info{ 0 };
process_startup_info.cb = sizeof(process_startup_info); // setup size of strcture in bytes
PROCESS_INFORMATION process_info{ 0 };
wchar_t commandline_args[] = L"\"C:\\Windows\\system32\\mspaint.exe\" Z:\\cat.PNG";
if (CreateProcessW(NULL, commandline_args, NULL, NULL, TRUE, 0, NULL, NULL, &process_startup_info, &process_info))
{
//WaitForSingleObject(process_info.hProcess, INFINITE); // uncomment to wait till process finish
CloseHandle(process_info.hProcess);
CloseHandle(process_info.hThread);
}
I strongly recommend to read this CodeProject article (A newbie's elementary guide to spawning processes).
The CreateProcess function can only start .exe and .bat files. Use ShellExecute[Ex] if you want to launch files the same way the shell/Explorer does.
A process must have a PE EXE file as its main file and if you ask CreateProcess to start something else it is just going to fail. ShellExecute will look up the file extension in the registry to find the correct executable (or COM handler) to execute and this often ends up calling CreateProcess on your behalf with the file you specified as a command line parameter.
Using ShellExecuteEx with the SEE_MASK_NOCLOSEPROCESS flag might might give you a process handle you can wait on but you also have to be prepared for hProcess being NULL. This can happen if the registered application for the file type is already running and DDE or COM was used to open the file in this existing application instance...
I am trying to use the CreateProcess() function in order to launch an .exe application that is in a folder in my root directory (the directory where my VS solution is). Seems simple right? It probably is but I can't for the life of me notice what I have done wrong. Every time I try to launch the .exe I get the error message "CreateProcess failed code 2" which means that the .exe file I am trying to launch cant be found.
My code:
void HavNetProfiler::LaunchClumsy()
{
STARTUPINFO si;
PROCESS_INFORMATION pi;
ZeroMemory(&si, sizeof(si));
si.cb = sizeof(si);
ZeroMemory(&pi, sizeof(pi));
// Start the child process.
if (!CreateProcess((LPCTSTR)"Clumsy\\clumsy.exe", // No module name (use command line)
NULL, // Command line
NULL, // Process handle not inheritable
NULL, // Thread handle not inheritable
FALSE, // Set handle inheritance to FALSE
0, // 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);
}
Am I using this function wrong? Have I misunderstood how it works or have I simply missed some minor detail? I am calling the function LaunchClumsy() in a file that is placed in a different folder (that folder exists in the root folder just like the "Clumsy" folder though). Would that make a difference?
Thanks!
There are 2 immediate bugs in the code:
The LPCTSTR cast is wrong. If your code does not compile without that cast, you have passed an argument with the wrong character encoding. Change it to L"Clumsy\\clumsy.exe" to explicitly pass a wide-character string.
Using a relative path is very likely to fail. The system searches starting from the current working directory. That is a process-wide property, that can be altered by any thread, at any time. Use an absolute path instead.
When I call CreateProcess in Windows, the new process doesn't seem to inherit the console of the calling process. I made a test program that runs "ruby xtest", xtest being a script that writes "hello" to standard output. I ran this test program from Emacs, and get no output. I also tried the following code calling GetStdHandle, but again, no output. Then I tried passing CREATE_NEW_CONSOLE in dwCreationFlags to CreateProcess, which made a whole new window with the Ruby output. Finally, I made a simple fork/exec
test program and compiled it using Cygwin's GCC. This program worked: the Ruby output showed up in Emacs as expected. I tried to decipher the Cygwin source code in http://cygwin.com/cgi-bin/cvsweb.cgi/src/winsup/cygwin/spawn.cc?rev=1.268&content-type=text/x-cvsweb-markup&cvsroot=src but failed. So, how do you make the new process inherit the console of the parent process such that the output from the child shows up as expected?
STARTUPINFO si;
PROCESS_INFORMATION pi;
memset(&si, 0, sizeof(si));
memset(&pi, 0, sizeof(pi));
si.dwFlags |= STARTF_USESTDHANDLES;
si.hStdInput = GetStdHandle(STD_INPUT_HANDLE);
si.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
si.hStdError = GetStdHandle(STD_ERROR_HANDLE);
if(!CreateProcess(0, "ruby xtest", 0, 0, 1, 0, 0, 0, &si, &pi)) die("CreateProcess");
I know, this thread is rather old, however, I just ran into the same problem.
Just as for the TS, the console handle was inherited and working fine under Cygwin, but not on a Windows console. Instead, the output on stdout was neither shown, nor any error was reported. Inherited Pipe handles worked still fine.
I took me some time to identify the (now obvious) problem: CreateProcess() was called with CREATE_NO_WINDOW. Dropping this flag, console output is fine. (Though, according to the code of the TS, they never set this flag in the first place.)
Hope this might be helpful for people who also stumble across this thread, like myself.
According to Microsoft documentation, lpCommandLine (2. parameter):
The Unicode version of this function, CreateProcessW, can modify the contents of this string. Therefore, this parameter cannot be a pointer to read-only memory (such as a const variable or a literal string). If this parameter is a constant string, the function may cause an access violation.
When I stopped using a constant here it worked for me. I didn't need the STARTF_USESTDHANDLES and GetStdHandle thing.
This code from a console prg runs and outputs another console exe in the same console:
FillChar(SI, SizeOf(SI), 0);
SI.cb:=SizeOf(SI);
FillChar(PI, SizeOf(PI), 0);
if CreateProcess(nil, CmdLineVar, nil, nil, False, 0, nil, nil, SI, PI) then ...
I've done this by passing in pipes for hStdInput, hStdOutput, and hStdError and manually routing data from the hStdOutput and hStdError pipes to the console.
Not sure if debeige ever solved this, but I needed the same thing, but starting up another thread to listen to stdout output, just to put it on stdout seemed nuts to me.
The following works for me, and is slightly different than what he originally posted. I thought at first it wouldn't work if you don't set si.cb, but when I commented that in mine, it still worked, so... YMMV.
STARTUPINFO siStartInfo;
ZeroMemory( &siStartInfo, sizeof(STARTUPINFO) );
siStartInfo.cb = sizeof(STARTUPINFO);
siStartInfo.hStdError = GetStdHandle(STD_OUTPUT_HANDLE);
siStartInfo.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
siStartInfo.hStdInput = g_hChildStd_IN_Rd; // my outgoing pipe
siStartInfo.dwFlags |= STARTF_USESTDHANDLES;
// Create the child process.
bSuccess = CreateProcess(
NULL,
szCmdline,
NULL,
NULL,
TRUE,
0,
NULL,
NULL,
&siStartInfo,
&piProcInfo);
What's the easiest way to duplicate the current process, to spawn another instance in Windows? I know Linux has fork(), but all I need is to run main in the same process again, probably using CreateProcess() with the correct arguments.
As #DavidHeffernan commented:
STARTUPINFO si;
::memset(&si, 0, sizeof(si));
si.cb = sizeof(si);
PROCESS_INFORMATION pi;
::CreateProcess(NULL, ::GetCommandLine(), NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi);
Cygwin implements fork() within its managed environment, but even that is an intricate square dance in getting the child to catch up with the parent to accurately replicate POSIX behavior.
It seems like you don't need to emulate fork(), but fork()/exec(). For that, gathering the environment variables, program parameters and passing them to CreateProcess() should be enough. There are options to copy the file descriptors to the child too. See CreateProcess's documentation.
I am using CreateProcess() to run an external console application in Windows from my GUI application. I would like to somehow gather the output to know whether there were errors. Now I know I have to do something with hStdOutput, but I fail to understand what. I am new to c++ and an inexperienced programmer and I actually don't know what to do with a handle or how to light a pipe.
How do I get the output to some kind of variable (or file)?
This is what I have a the moment:
void email::run(string path,string cmd){
WCHAR * ppath=new(nothrow) WCHAR[path.length()*2];
memset(ppath,' ',path.length()*2);
WCHAR * pcmd= new(nothrow) WCHAR[cmd.length()*2];
memset(pcmd,' ',cmd.length()*2);
string tempstr;
ToWCHAR(path,ppath); //creates WCHAR from my std::string
ToWCHAR(cmd,pcmd);
STARTUPINFO info={sizeof(info)};
info.dwFlags = STARTF_USESHOWWINDOW; //hide process
PROCESS_INFORMATION processInfo;
if (CreateProcess(ppath,pcmd, NULL, NULL, FALSE, 0, NULL, NULL, &info, &processInfo))
{
::WaitForSingleObject(processInfo.hProcess, INFINITE);
CloseHandle(processInfo.hProcess);
CloseHandle(processInfo.hThread);
}
delete[](ppath);
delete[](pcmd);
}
This code probably makes any decent programmer scream, but (I shouldn't even say it:) It works ;-)
The Question: How do I use hStdOutput to read the output to a file (for instance)?
Microsoft has an example in its knowledge base that demonstrates how to capture the output of a child console process. The basic principle is that the parent process creates pipes (one per standard handle to redirect) and passes the handles to CreateProcess.
The child process does not need to be modified for this to work, which is important if you do not have control over the child's source.
More information: How to spawn console processes with redirected standard handles