main 함수의 앞차례 실행 과정에 대한 간단한 소개

main 함수의 앞차례 실행 과정에 대한 간단한 소개
main 함수는 사실 우리가 제어할 수 있는 프로그램 입구이지만 프로그램이 컴파일된 후에 실행하는 것은main 함수로부터 시작되는 것이 아니다. 여기서 주로 VC6를 설명한다.0++에서 컴파일된 프로그램이main 함수를 실행하기 전의 절차는main 함수를 실행하기 전에 환경 변수와 매개 변수 개수, 매개 변수의 해석을 한 다음에 전역 변수, 더미,io 등의 내용을 초기화하기 위한 것이다.

/***
*crt0.c - C runtime initialization routine
*
*       Copyright (c) 1989-1997, Microsoft Corporation. All rights reserved.
*
*Purpose:
*       This the actual startup routine for apps.  It calls the user's main
*       routine [w]main() or [w]WinMain after performing C Run-Time Library
*       initialization.
*
*       (With ifdef's, this source file also provides the source code for
*       wcrt0.c, the startup routine for console apps with wide characters,
*       wincrt0.c, the startup routine for Windows apps, and wwincrt0.c,
*       the startup routine for Windows apps with wide characters.)
*
*******************************************************************************/

#ifdef _WIN32

#ifndef CRTDLL

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

/*
 * wWinMain is not yet defined in winbase.h. When it is, this should be
 * removed.
 */

int
WINAPI
wWinMain(
    HINSTANCE hInstance,
    HINSTANCE hPrevInstance,
    LPWSTR lpCmdLine,
    int nShowCmd
    );

#ifdef WPRFLAG
_TUCHAR * __cdecl _wwincmdln(void);
#else  /* WPRFLAG */
_TUCHAR * __cdecl _wincmdln(void);
#endif  /* WPRFLAG */

/*
 * command line, environment, and a few other globals
 */

#ifdef WPRFLAG
wchar_t *_wcmdln;           /* points to wide command line */
#else  /* WPRFLAG */
char *_acmdln;              /* points to command line */
#endif  /* WPRFLAG */

char *_aenvptr = NULL;      /* points to environment block */
wchar_t *_wenvptr = NULL;   /* points to wide environment block */


void (__cdecl * _aexit_rtn)(int) = _exit;   /* RT message return procedure */

static void __cdecl fast_error_exit(int);   /* Error exit via ExitProcess */

/*
 * _error_mode and _apptype, together, determine how error messages are
 * written out.
 */
int __error_mode = _OUT_TO_DEFAULT;
#ifdef _WINMAIN_
int __app_type = _GUI_APP;
#else  /* _WINMAIN_ */
int __app_type = _CONSOLE_APP;
#endif  /* _WINMAIN_ */


/***
*BaseProcessStartup(PVOID Peb)
*
*Purpose:
*       This routine does the C runtime initialization, calls main(), and
*       then exits.  It never returns.
*
*Entry:
*       PVOID Peb - pointer to Win32 Process Environment Block (not used)
*
*Exit:
*       This function never returns.
*
*******************************************************************************/

#ifdef _WINMAIN_

#ifdef WPRFLAG
void wWinMainCRTStartup(
#else  /* WPRFLAG */
//     main       
void WinMainCRTStartup(
#endif  /* WPRFLAG */

#else  /* _WINMAIN_ */

#ifdef WPRFLAG
void wmainCRTStartup(
#else  /* WPRFLAG */
void mainCRTStartup(
#endif  /* WPRFLAG */

#endif  /* _WINMAIN_ */
        void
        )

{
        int mainret;

#ifdef _WINMAIN_
        _TUCHAR *lpszCommandLine;
        STARTUPINFO StartupInfo;
#endif  /* _WINMAIN_ */

        /*
         * Get the full Win32 version
         */
         //             
        _osver = GetVersion();
		//                  
        _winminor = (_osver >> 8) & 0x00FF ;
        _winmajor = _osver & 0x00FF ;
        _winver = (_winmajor << 8) + _winminor;
        _osver = (_osver >> 16) & 0x00FFFF ;

#ifdef _MT
	   //      
        if ( !_heap_init(1) )               /* initialize heap */
#else  /* _MT */
        if ( !_heap_init(0) )               /* initialize heap */
#endif  /* _MT */
            fast_error_exit(_RT_HEAPINIT);  /* write message and die */

#ifdef _MT
        //                 
        if( !_mtinit() )                    /* initialize multi-thread */
            fast_error_exit(_RT_THREAD);    /* write message and die */
#endif  /* _MT */

        /*
         * Guard the remainder of the initialization code and the call
         * to user's main, or WinMain, function in a __try/__except
         * statement.
         */

        __try {
			//   IO	
            _ioinit();                      /* initialize lowio */

#ifdef WPRFLAG
            /* get wide cmd line info */
            //         ，        
            _wcmdln = (wchar_t *)__crtGetCommandLineW();

            /* get wide environ info */
            //        ，           
            _wenvptr = (wchar_t *)__crtGetEnvironmentStringsW();
           //       main   argv  
            _wsetargv();
            //           
            _wsetenvp();
#else  /* WPRFLAG */
            //               
            /* get cmd line info */
            _acmdln = (char *)GetCommandLineA();

            /* get environ info */
            _aenvptr = (char *)__crtGetEnvironmentStringsA();

            _setargv();
            _setenvp();
#endif  /* WPRFLAG */
            //              ，                        
            _cinit();                       /* do C data initialize */
//  WINMAIN         GUI           
#ifdef _WINMAIN_
            StartupInfo.dwFlags = 0;
            //         
            GetStartupInfo( &StartupInfo );

#ifdef WPRFLAG
            //          Unicode     Unicode      
            lpszCommandLine = _wwincmdln();
            mainret = wWinMain(
#else  /* WPRFLAG */
            lpszCommandLine = _wincmdln();
            mainret = WinMain(
#endif  /* WPRFLAG */
                               GetModuleHandleA(NULL),
                               NULL,
                               lpszCommandLine,
                               StartupInfo.dwFlags & STARTF_USESHOWWINDOW
                                    ? StartupInfo.wShowWindow
                                    : SW_SHOWDEFAULT
                             );
#else  /* _WINMAIN_ */

#ifdef WPRFLAG
           //                  main  
            __winitenv = _wenviron;
            mainret = wmain(__argc, __wargv, _wenviron);
#else  /* WPRFLAG */
            __initenv = _environ;
            mainret = main(__argc, __argv, _environ);
#endif  /* WPRFLAG */

#endif  /* _WINMAIN_ */
 //      main  
  exit(mainret);
      }
  //     windows       (SEH)，     _XcptFilter               ，           ，                 
  //GetExceptionCode           
  //   SEH               （exception code）。     GetExceptionCode()        。     GetExceptionInformation()       
  __except ( _XcptFilter(GetExceptionCode(), GetExceptionInformation()) )
        {
            /*
             * Should never reach here
             */
             //   
            _exit( GetExceptionCode() );

        } /* end of try - except */
}

정보XcptFilter 함수는 사실 이상을 식별하고 관련 조작을 하는 것이다
int __cdecl _XcptFilter( unsigned long xcptnum, PEXCEPTION_POINTERS pxcptinfoptrs ); [in] xcptnum 이상 식별자입니다.[in] pxcptinfoptrs가 비정상적인 정보를 가리키는 바늘입니다.