Log in file for Visual Studio

logging_VisualStudio.cpp

typedef enum {
    LOG_INFO = 0,   /**< Notification for better debugging */
    LOG_WARNING = 1,/**< Incorrect work of application, but it doesn't lead to crash */
    LOG_ERROR = 2   /**< Big problem - application is crashed */
} logLevel_e;

static FILE *g_logStream = NULL;
static WCHAR g_logFilePath[MAX_PATH];
static WCHAR g_logMessage[10000];

/** @brief Write to logs messages to file. Also, in debugging, display them in window "Output".
 *  @param level - criticality level of message.
 *  @param format - format of logged message.
 *  @see printf()
 */
void logging(logLevel_e level, WCHAR* format, ...)
{
    va_list argptr;
    va_start(argptr, format);
    _vsnwprintf_s(g_logMessage, ARRAYSIZE(g_logMessage), format, argptr);
    va_end(argptr);

    OutputDebugString(g_logMessage);
    OutputDebugString(L"\n");

    if (g_logStream != NULL) {
        SYSTEMTIME time;
        GetLocalTime(&time);
        fwprintf(g_logStream, L"%02d:%02d:%02d.%03d ",
                 time.wHour, time.wMinute, time.wSecond, time.wMilliseconds);

        switch (level) {
        case LOG_INFO:    fwprintf(g_logStream, L"Info: ");  break;
        case LOG_WARNING: fwprintf(g_logStream, L"Warn: ");  break;
        case LOG_ERROR:   fwprintf(g_logStream, L"Error: "); break;
        }

        fwprintf(g_logStream, L"%s\n", g_logMessage);
        fflush(g_logStream);
    }
}

/** @brief Open log file log_autorun.txt in system temporary directory.
*/
void openLogFile()
{
    TCHAR tempDirectory[MAX_PATH];
    DWORD dwRetVal = 0;

    //  Gets the temp path env string (no guarantee it's a valid path).
    dwRetVal = GetTempPath(MAX_PATH, tempDirectory);
    if (dwRetVal > MAX_PATH || (dwRetVal == 0)) {
        logging(LOG_ERROR, L"GetTempPath failed");
        return;
    }

    swprintf(g_logFilePath, ARRAYSIZE(g_logFilePath), L"%slog_autorun.txt", tempDirectory);
    logging(LOG_INFO, L"Open log file %s", g_logFilePath);
    //  Open file for writing. Truncate it. Set ability to flush on disk and set encoding - Unicode UTF-8
    errno_t err = _wfopen_s(&g_logStream, g_logFilePath, L"wc,ccs=UTF-8");
    if (err != 0)
        logging(LOG_ERROR, L"Opening log file failed. Error: %d", err);
}

int main(...)
{
    openLogFile();
    logging(LOG_INFO, L"Start");
    ...
    logging(LOG_INFO, L"Application has been successfully finished");
    if (g_logStream != NULL)
        fclose(g_logStream);
}