New process in Windows API [duplicate] - winapi

Question

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CreateProcess() fails with an access violation [duplicate]
(3 answers)
Closed 8 years ago.
I work with WinAPI and I have a function that creates a new process:
void new_process() {
STARTUPINFO si = { sizeof(si) };
PROCESS_INFORMATION pi;
TCHAR szCommandLine[] = TEXT("NOTEPAD");
CreateProcess(NULL, szCommandLine, NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi);
}
But when I call this function from main(), it's doesn't work:
void new_process(TCHAR szCommandLine[]) {
STARTUPINFO si = { sizeof(si) };
PROCESS_INFORMATION pi;
CreateProcess(NULL, szCommandLine, NULL, NULL, FALSE, 0, NULL, NULL, &si, &pi);
}
int _tmain(int argc, _TCHAR* argv[]) {
new_process(TEXT("NOTEPAD"));
return 0;
}
Where is my mistake?

Answer 1

The problem is explained here. MSDN says -
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 you pass TEXT("NOTEPAD") as the parameter to the function new_process(TCHAR szCommandLine[]) which in turn passes this as the lpCommandLine parameter to the CreateProcess() API, it will try to modify this location as quoted from MSDN above.
Since the parameter TEXT("NOTEPAD") is a CONSTANT memory, when the CreateProcess() tries to modify this memory as quoted above, it will cause memory access violation.
So ideally you should call the function new_process(TCHAR szCommandLine[]) from the main() function as given below.
TCHAR APP_NAME[] = TEXT("NOTEPAD");
new_process(APP_NAME);
Hope this help!