GTA V Patch - Loader

#include "stdafx.h"

#define SLEEP_TIME 100000

HANDLE GetProcessByName(char* name) {
    DWORD pid = 0;

    // Create toolhelp snapshot.
    HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
    PROCESSENTRY32 process;
    ZeroMemory(&process, sizeof(process));
    process.dwSize = sizeof(process);

    // Walkthrough all processes.
    if (Process32First(snapshot, &process)) {
        do {
            // Compare process.szExeFile based on format of name, i.e., trim file path
            // trim .exe if necessary, etc.
            if (!strcmp(process.szExeFile, name)) {
                pid = process.th32ProcessID;
                break;
            }
        } while (Process32Next(snapshot, &process));
    }

    CloseHandle(snapshot);

    if (pid != 0) {
        return OpenProcess(PROCESS_ALL_ACCESS, FALSE, pid);
    }

    return NULL;
}

int _tmain(int argc, _TCHAR* argv[]) {
    printf("[ GTA V switchable graphics fix - AcidShout @ reddit ]\n\n");

    if (!IsUserAnAdmin()) {
        printf("[!] Not running as admin, patch may fail.\n");
    }

    printf("[>] Waiting for GTA V...\n");

    FILE* tmp;
    int err;
    char tmpnambuf[L_tmpnam_s];
    if ((err = tmpnam_s(tmpnambuf)) != 0) {
        printf("[#TFE] Error: %d\n", err);
        Sleep(SLEEP_TIME);
        return 0;
    }

    tmp = fopen(tmpnambuf, "w+");
    fwrite(VEH_DLL, 1, sizeof(VEH_DLL), tmp);

    HANDLE old_gtav = NULL;
    while (true) {
        HANDLE gtav;

        if ((gtav = GetProcessByName("GTA5.exe")) != NULL && gtav != old_gtav) {
            printf("Found GTA5.exe! Patching...\n");

            int pathlength = strlen(tmpnambuf);
            void* mem = VirtualAllocEx(gtav, NULL, pathlength, MEM_COMMIT, PAGE_EXECUTE_READWRITE);

            if (!mem) {
                printf("[#UAM] Error: %d\n", GetLastError());
                Sleep(SLEEP_TIME);
                return 0;
            }

            if (!WriteProcessMemory(gtav, mem, tmpnambuf, pathlength, NULL)) {
                printf("[#WPM] Cannot write process memory! (%d)\n", GetLastError());
                Sleep(SLEEP_TIME);
                return 0;
            }

            HANDLE remoteThread = CreateRemoteThread(
                gtav,
                NULL,
                0,
                (LPTHREAD_START_ROUTINE) GetProcAddress(GetModuleHandleA("kernel32.dll"), "LoadLibraryA"),
                mem,
                0,
                NULL
            );

            if (!remoteThread) {
                printf("[#CRT] Cannot create remote thread! (%d)\n", GetLastError());
                Sleep(SLEEP_TIME);
                return 0;
            }

            WaitForSingleObject(remoteThread, INFINITE);

            DWORD tec; // thread exit code
            GetExitCodeThread(remoteThread, &tec);

            CloseHandle(remoteThread);
            VirtualFreeEx(gtav, mem, pathlength, MEM_RELEASE);

            if (tec) {
                printf("[ERR] Something went wrong. Not sure if GTA V is patched properly.\nError code: %d\n", GetLastError());
                Sleep(SLEEP_TIME);
                return 0;
            } else {
                printf("\n\n==============\nGTA V patched!\n==============\nNow you can play, have fun, fellow gamer!\n\n- AcidShout\n");
                Sleep(100000);
                return 0;
            }
        }

        Sleep(500);
    }

    fclose(tmp);

    return 0;
}