Starting Speech Recognition with CreateProcess() in C++ - c++

Question

I need help with my simple program, which tries to create a new process running Speech recognition.
When I open cmd and type in the command C:\Windows\Speech\Common\sapisvr.exe -SpeechUX then the speech recognition would successfully start. It will start even when running through system(C:\\Windows\\...) which basically just mimics cmd.
However, when creating the new process with CreateProcess() as below, the function fails. If I put whole path and argument into second parameter CreateProcess(NULL, TEXT("C:\\Windows...\\sapisvr.exe -SpeechUX"), ...), then I get a runtime exception: Access violation writing location
#include <windows.h>
int main()
{
STARTUPINFO si;
PROCESS_INFORMATION pi;
ZeroMemory(&si, sizeof(si));
si.cb = sizeof(si);
ZeroMemory(&pi, sizeof(pi));
if (!CreateProcess(
TEXT("C:\\Windows\\Speech\\Common\\sapisvr.exe"), //Module name
TEXT(" -SpeechUX"), //command line params
NULL, //Process attributes
NULL, //Thread attributes
FALSE, //Handle inheritance
0, //No creation flags
NULL, //Use parent's environment
NULL, //Use parent's starting directory
&si, //Pointer to STARTUPINFO structure
&pi )) //Pointer to PROCESS_INFORMATION structure
{
printf("error creating process\n");
return 1;
}
WaitForSingleObject(pi.hProcess, INFINITE);
CloseHandle(pi.hProcess);
CloseHandle(pi.hThread);
return 0;
}
First I tried to test CreateProcess function with running notepad with an argument to open an existing file. When I put path to notepad.exe to first parameter and name of the file to the command line parameter, it didn't recognise it and opened a new file instead.
This whole applies as well to trying to run msconfig.exe from my program, which doesn't take any parameters, so I guess the problem is somewhere else, I just have no idea where.
I searched the web and none of the answers actually worked for me. I'm working in Visual Studio 2015 on Windows 8.1.
Thanks for help.

Answer 1

The CreateProcess function has a second argument as an LPTSTR. For the CreateProcessW version of this function, this must be a writeable buffer, not a string literal. Thus your program's behavior is undefined. Since you are getting an access violation writing to a location when calling CreateProcess, we will assume that CreateProcess is being mapped to CreateProcessW.
At the link posted, here is the quote:
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.
So the fix is simply define an array, not a literal:
TCHAR commandParam[] = TEXT(" -SpeechUX");
if (!CreateProcess(TEXT("C:\\Windows\\Speech\\Common\\sapisvr.exe"),
commandParam,
...
}
or if passing NULL as the first argument:
TCHAR commandParam[] = TEXT("C:\\Windows\\Speech\\Common\\sapisvr.exe");
//...
if (!CreateProcess(NULL, commandParam, ...
Also, if CreateProcess returns an error, you should call GetLastError and optionally FormatMessage, to get the error that occurred, and not simply output that there is an error.