Wide string command line arguments in C

Question

I'm writing a program that what it does first, is to retrieve the first command line argument (which should be a process name), and find the corresponding PID of the process.

Here's how I do it:

in main

DWORD PID = FindProcessId(argv[1]);

and here's the function that finds PID:

DWORD FindProcessId(PWCHAR processname)
{
    NTSTATUS status;
    PVOID buffer;
    PSYSTEM_PROCESS_INFORMATION spi;
    DWORD pid = 0;

    buffer = VirtualAlloc(NULL, 1024 * 1024, MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
    spi = (PSYSTEM_PROCESS_INFORMATION)buffer;

    status = NtQuerySystemInformation(SystemProcessInformation, spi, 1024 * 1024, NULL);

    while (spi->NextEntryOffset) // Loop over the list until we reach the last entry, or found PID.
    {
        if (wcsncmp(spi->ImageName.Buffer, processname, spi->ImageName.Length) == 0)
        {
            pid = spi->UniqueProcessId;
            break;
        }
        spi = (PSYSTEM_PROCESS_INFORMATION)((LPBYTE)spi + spi->NextEntryOffset); // Calculate the address of the next entry.

    }

    return pid;
}

The thing is, it works perfectly if i simply write

DWORD PID = FindProcessId(L"notepad.exe");,

for example.

But when i use the command line argument and runthe program like so: find_pid.exe notepad.exe the FindProcessId returns 0, meaning it didn't find the process. Even though notepad.exe is running like before.

Any ideas why this doesn't work with the command line argument?

---

To make the program accept PWCHAR rather than char * (Wide strings rather than ascii ones), I had to use main instead of wmain

Answer 1

To make the program accept PWCHAR rather than char * (Wide strings rather than ascii ones), I had to use wmain instead of main, like so:

int wmain(int argc, PWCHAR argv[])
{
    ....
    return 0;
}

OR

Just convert the char * to a wide string - PWCHAR, like so:

WCHAR victimProcessName[MAX_PATH];
mbstowcs(victimProcessName, argv[1], MAX_PATH); // Plus null