CreateProcessA,Wait and ExitCode in C - getting wrong exit code

Question

I have a problem with my code in C that uses CreateProcessA and Wait(...) functions. Everything seems to work fine, except exit code. It's always 0. I know (at least) this part of the code (with exit code) is wrong, but I tried many ways to fix it and none on them actually worked. Also, PIDs, when displaying them in console, sometimes are not where they are supposed to be (for example: There are 3 rows with the same PID, and sometimes there is one extra PID from other group, something like: 6656 6656 1234 6656...). Maybe you guys know the solution. Here is the code:

    ...//some argument conditions above
    STARTUPINFO si;
    PROCESS_INFORMATION pi[2];

    memset(&si, 0, sizeof(si));
    memset(&pi, 0, sizeof(pi));
    si.cb = sizeof(si);

    int argument = atoi(argv[1]);   
    int argument1 = argument - 1;
    int argument2 = argument - 2;

    char a1[50];
    sprintf(a1, "file.exe %d", argument1);

    BOOL v1 = CreateProcessA("file.exe", a1, NULL, NULL, FALSE, 0, NULL, NULL, &si, pi+0);


    char a2[50];
    sprintf(a2, "file.exe %d", argument2);

    BOOL v2 = CreateProcessA("file.exe", a2, NULL, NULL, FALSE, 0, NULL, NULL, &si, pi+1);


    
    HANDLE children[2] = { pi[0].hProcess, pi[1].hProcess };
    WaitForMultipleObjects(2, children, 1, INFINITE);
    for (int i = 1; i >= 0; i--)
    {       
        CloseHandle(pi[i].hProcess);
        CloseHandle(pi[i].hThread);
    }

    unsigned long int exit1 = GetExitCodeProcess(children[0], &exit1);
    unsigned long int exit2 = GetExitCodeProcess(children[1], &exit2);
    
    printf("%d \t %d \t %d \t %d \t\n", GetCurrentProcessId(), pi[0].dwProcessId, argument1, exit1);

    
    printf("%d \t %d \t %d \t %d \t\n", GetCurrentProcessId(), pi[1].dwProcessId, argument2, exit2);

    printf("%d \t \t \t %d\n\n", GetCurrentProcessId(), exit1 + exit2);


    return exit1 + exit2;
}

Thanks for any help.

Answer 1

In this code:

    HANDLE children[2] = { pi[0].hProcess, pi[1].hProcess };
    WaitForMultipleObjects(2, children, 1, INFINITE);
    for (int i = 1; i >= 0; i--)
    {       
        CloseHandle(pi[i].hProcess);
        CloseHandle(pi[i].hThread);
    }

    unsigned long int exit1 = GetExitCodeProcess(children[0], &exit1);
    unsigned long int exit2 = GetExitCodeProcess(children[1], &exit2);

One problem is that exit1 and exit2 are being initialized to the return values of GetExitCodeProcess. That function has a return type of BOOL and returns 0 (FALSE) on failure, or a non-zero value (presumably 1 (TRUE)) on success. Since the process handles have already been closed in the preceding for loop, GetExitCodeProcess will return the failure value 0.

Try changing it to to the following:

    HANDLE children[2] = { pi[0].hProcess, pi[1].hProcess };
    WaitForMultipleObjects(2, children, 1, INFINITE);
    DWORD exit1, exit2;
    GetExitCodeProcess(children[0], &exit1);
    GetExitCodeProcess(children[1], &exit2);
    for (int i = 1; i >= 0; i--)
    {       
        CloseHandle(pi[i].hProcess);
        CloseHandle(pi[i].hThread);
    }