I'm opened opening a process (with C++/Windows) using
if( CreateProcessA( NULL, // No module name (use command line)
(LPSTR)path, //argv[1], // Command line
NULL, // Process handle not inheritable
NULL, // Thread handle not inheritable
FALSE, // Set handle inheritance to FALSE
creationFlags, // No creation flags
NULL, // Use parent's environment block
NULL, // Use parent's starting directory
&startInfo, // Pointer to STARTUPINFO structure
&processInfo ) // Pointer to PROCESS_INFORMATION structure
where
DWORD creationFlags = DEBUG_PROCESS | DEBUG_ONLY_THIS_PROCESS;
and then I'm trying to stackwalk it with
bool ok = StackWalk64(IMAGE_FILE_MACHINE_I386,m_ps.Handle ,m_th.Handle,
&m_stackframe, &m_threadContext,
0, NULL, NULL, 0);
but stackwalk just gives me the top address and the next one is 0, while I know there are more addresses in the stack.
Does anybody know what's the problem?
thanks :)
It's impossible to tell based on this snippet. There's so much you have to set up correctly in order for this to work. Check out the logic at this detailed blog post.
Post more code if you can post a bigger but not too big sample. How are you setting up the STACKFRAME and CONTEXT structures? Are you looping on StackWalk64? Any given call only returns one stack frame.
oops... I forget to call "ContinueDebugEvent" after receiving events from the debugged process - so it stayed paused and the StackWalk was infact correct. :)
Related
I have a third party console application in term as "reg.exe". When I run it, it shows me a text message. I want to use this string in my application.
How do I get this string?
I want to use CreatProcess to execute "reg.exe",
CreateProcess( NULL, // No module name (use command line)
argv[1], // 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
Then use
WaitForSingleObject( pi.hProcess, INFINITE );
to wait it to be finished.
After a successful call to CreateProcess, I am trying to get the path of the created process using GetModuleFileNameEx (lpApplicationName and lpCommandLine parameters can vary or be null so they aren't reliable in this case).
The problem is that GetModuleFileNameEx fails with error 6 (ERROR_INVALID_HANDLE), leaving its buffer with invalid data. I cannot understand the reason, since CreateProcess succeeds and process handle should have been saved correctly in pi.hProcess.
Hope you can shed some light, thanks in advance!
EDIT: An update: I noticed that removing the CREATE_SUSPENDED removes this problem too, but I need that flag set. How can I do?
// Defining GetModuleFileNameExA function
typedef DWORD (WINAPI *fGetModuleFileNameExA)
(
HANDLE hProcess,
HMODULE hModule,
LPSTR lpFilename,
DWORD nSize
);
//Load dinamically DLL function on program startup:
fGetModuleFileNameExA _GetModuleFileNameExA = (fGetModuleFileNameExA) GetProcAddress( LoadLibraryA("Psapi.dll"), "GetModuleFileNameExA");
// **** OTHER UNRELATED CODE HERE ****
PROCESS_INFORMATION pi;
//This call succeeds
if (!CreateProcessW( ApplicationName,
CommandLine,
NewProcess.lpProcessAttributes,
NewProcess.lpThreadAttributes,
NewProcess.bInheritHandles,
CREATE_SUSPENDED | CREATE_NEW_CONSOLE,
NULL,
CurrentDirectory,
&NewProcess.bufStartupInfo,
&pi)
) MessageBoxA(0, "Error creating process", "", 0);
char ProcessPath[MAX_PATH];
//Problem here: call fails with error 6
if (!_GetModuleFileNameExA(pi.hProcess, NULL, ProcessPath, MAX_PATH)) {GetLastError();}
//Invalid data is displayed
MessageBoxA(0, ProcessPath, "GetModuleFileNameEx",0);
From the CreateProcess documentation on MSDN:
Note that the function returns before the process has finished initialization. If a required DLL cannot be located or fails to initialize, the process is terminated. To get the termination status of a process, call GetExitCodeProcess.
...
The calling thread can use the WaitForInputIdle function to wait until the new process has finished its initialization and is waiting for user input with no input pending. This can be useful for synchronization between parent and child processes, because CreateProcess returns without waiting for the new process to finish its initialization. For example, the creating process would use WaitForInputIdle before trying to find a window associated with the new process.
Similar question
I've coded two processes using C++. One is the GUI process that is called by my console app using CreateProcess API. I need to pass text from the GUI app (child) to the console app (parent.) The amount of text could be arbitrary -- from a few lines to KBs of text.
What is the easiest way to do it?
PS. I have access to the source code of both processes.
Console application can create a WinAPI window (non-visible), such that it can receive messages (idea taken from AllocateHWND function in Delphi).
Another solution is to use named pipes.
Another solution is to send data locally via TCP/IP.
If these strings are only a debug ones, consider using OutputDebugString function from WinAPI and capturing them with a program like SysInternals' DbgView.
If the GUI application is truly graphical only, you don't really use the standard output stream (i.e. std::cout). This can the be reused for output to your console application.
First you need to create an anonymous pipe using CreatePipe:
HANDLE hPipeRead;
HANDLE hPipeWrite;
CreatePipe(&hPipeRead, &hPipeWrite, NULL, 0);
Now you have to handles that can be used as a normal file handle; One to read from and the other to write to. The write-handle should be set as the standard output for the new process you create:
STARTUPINFO startupInfo = { 0 };
startupInfo.cb = sizeof(startupInfo);
startupInfo.dwFlags = STARTF_USESTDHANDLES;
startupInfo.hStdOutput = hPipeWrite; // Standard output of the new process
// is set to the write end of the pipe
CreateProcess(
lpApplicationName,
lpCommandLine,
NULL,
NULL,
FALSE,
0,
NULL,
NULL,
&startupInfo, // Use our startup information
&processInfo);
Now whenever the child process needs to write to the parent, it only have to use standard output:
std::cout << "In child process, are you getting this parent?";
The parent uses ReadFile to read from the read-end of the pipe:
char buffer[256];
DWORD bytesRead = 0;
ReadFile(hPipeRead, buffer, sizeof(buffer), &bytesRead, NULL);
Note: I haven't done WIN32 programming in some time, so might be wrong on some details. But should hopefully be enough to get you started.
There are of course many other ways if Inter Process Communications (IPC), including (but not limited to) sockets, files, shared memory, etc.
The easy way is probably to make the child actually a console application, even though it also creates windows.
In that case, you can have your parent spawn the child using _popen, and the child can just write the output to its normal stdout/std::cout. _popen returns a FILE *, so the parent can read the child's output about like it'd normally read a file (well, normally for C anyway).
Various methods can be used, some of them were given above. Which one is simplest depends on you task.
I can also suggest you filemapping technics which is widely used in IPC, and for ex. dll are implemented using filemapping.
It allows mutliply processes to share the same resources simultaniously, access is random not consequntial.
Here are main steps of implementation:
1. Process A creates a file;
2. Process A creates a named system object mappedfile to the file (mappedfile allocates memory);
3. Process A creates a system object a viewOfMapped file(this allows to map some area of the process A to the pages in the main memory which were allocated by mappedFile);
4. Process B creates the named system object mappedfile(name should be similar to the one of process A used), viewOfMapped file;
5. By pointers returned by viewOfMapped processes can share the same memory.
Example:
Process A:
/* 1. file creation */
hFile = CreateFile(0, GENERIC_READ | GENERIC_WRITE,FILE_SHARE_READ | FILE_SHARE_WRITE, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL,
NULL);
/* 2. Create file mapping */
wchar_t lpName[] = L"fileMappingObject0";
HANDLE hfileMappingObject;
hfileMappingObject = CreateFileMapping(hFile, NULL, PAGE_READWRITE, 0, 1024, lpName);
/* 3. Create MappedFileViewOfFile */
void* p = (MapViewOfFile(hfileMappingObject, FILE_MAP_ALL_ACCESS, 0, 0, 0));
Process B:
/* 2. Create file mapping */
wchar_t lpName[] = L"fileMappingObject0";
HANDLE hfileMappingObject;
hfileMappingObject = CreateFileMapping(hFile, NULL, PAGE_READWRITE, 0, 1024, lpName);
/* 3. Create MappedFileViewOfFile */
void* p = (MapViewOfFile(hfileMappingObject, FILE_MAP_ALL_ACCESS, 0, 0, 0));
This method is rather simple and also powerfull.
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
I am trying to create a program that calls another process using CreateProcess. After some problems, I change my program to just open a known program:
if( !CreateProcess( (LPWSTR)"C:\\Program Files\\Opera\\Opera.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
)
I found this example in msdn, but every time I run my program, windows (Vista) shows a error msg: The program stop running...
Does anybody know what is the problem?
Regards,
Leandro Lima
This line is wrong:
(LPWSTR)"C:\\Program Files\\Opera\\Opera.exe"
LPWSTR is a typedef for wchar_t*. So you're casting a plain string (array of chars, which will decay to a const char*) to a wchar_t*. The end result is likely not even null-terminated!
Either use CreateProcessA and drop the cast, or use a wide string:
L"C:\\Program Files\\Opera\\Opera.exe",