uplink.c

mediastreamer2是开源的网络传输媒体流的库

#if (defined(_WIN64) || defined(_WIN32_WCE)) && !defined(UNICODE)
#define UNICODE
#endif
#if defined(UNICODE) && !defined(_UNICODE)
#define _UNICODE
#endif
#if defined(_UNICODE) && !defined(UNICODE)
#define UNICODE
#endif

#include <windows.h>
#include <tchar.h>
#include <stdio.h>
#include "uplink.h"
void OPENSSL_showfatal(const char *,...);

static TCHAR msg[128];

static void unimplemented (void)
{   OPENSSL_showfatal (sizeof(TCHAR)==sizeof(char)?"%s\n":"%S\n",msg);
    ExitProcess (1);
}

void OPENSSL_Uplink (volatile void **table, int index)
{ static HMODULE volatile apphandle=NULL;
  static void ** volatile applinktable=NULL;
  int len;
  void (*func)(void)=unimplemented;
  HANDLE h;
  void **p;

    /* Note that the below code is not MT-safe in respect to msg
     * buffer, but what's the worst thing that can happen? Error
     * message might be misleading or corrupted. As error condition
     * is fatal and should never be risen, I accept the risk... */
    /* One can argue that I should have used InterlockedExchangePointer
     * or something to update static variables and table[]. Well,
     * store instructions are as atomic as they can get and assigned
     * values are effectively constant... So that volatile qualifier
     * should be sufficient [it prohibits compiler to reorder memory
     * access instructions]. */
    do {
	len = _stprintf (msg,_T("OPENSSL_Uplink(%p,%02X): "),table,index);
	_tcscpy (msg+len,_T("unimplemented function"));

	if ((h=apphandle)==NULL)
	{   if  ((h=GetModuleHandle(NULL))==NULL)
	    {	apphandle=(HMODULE)-1;
		_tcscpy (msg+len,_T("no host application"));
		break;
	    }
	    apphandle = h;
	}
	if ((h=apphandle)==(HMODULE)-1) /* revalidate */
	    break;

	if (applinktable==NULL)
	{ void**(*applink)();

	    applink=(void**(*)())GetProcAddress(h,"OPENSSL_Applink");
	    if (applink==NULL)
	    {	apphandle=(HMODULE)-1;
		_tcscpy (msg+len,_T("no OPENSSL_Applink"));
		break;
	    }
	    p = (*applink)();
	    if (p==NULL)
	    {	apphandle=(HMODULE)-1;
		_tcscpy (msg+len,_T("no ApplinkTable"));
		break;
	    }
	    applinktable = p;
	}

	if (index > (int)p[0])
	    break;

	if (p[index]) func = p[index];
    } while (0);

    table[index] = func;
}    

#if defined(_MSC_VER) && defined(_M_IX86) && !defined(OPENSSL_NO_INLINE_ASM)
#define LAZY(i)		\
__declspec(naked) static void lazy##i (void) { 	\
	_asm	push i				\
	_asm	push OFFSET OPENSSL_UplinkTable	\
	_asm	call OPENSSL_Uplink		\
	_asm	add  esp,8			\
	_asm	jmp  OPENSSL_UplinkTable+4*i	}

#if APPLINK_MAX>25
#error "Add more stubs..."
#endif
/* make some in advance... */
LAZY(1)  LAZY(2)  LAZY(3)  LAZY(4)  LAZY(5)
LAZY(6)  LAZY(7)  LAZY(8)  LAZY(9)  LAZY(10)
LAZY(11) LAZY(12) LAZY(13) LAZY(14) LAZY(15)
LAZY(16) LAZY(17) LAZY(18) LAZY(19) LAZY(20)
LAZY(21) LAZY(22) LAZY(23) LAZY(24) LAZY(25)
void *OPENSSL_UplinkTable[] = {
	(void *)APPLINK_MAX,
	lazy1, lazy2, lazy3, lazy4, lazy5,
	lazy6, lazy7, lazy8, lazy9, lazy10,
	lazy11,lazy12,lazy13,lazy14,lazy15,
	lazy16,lazy17,lazy18,lazy19,lazy20,
	lazy21,lazy22,lazy23,lazy24,lazy25,
};
#endif

#ifdef SELFTEST
main() {  UP_fprintf(UP_stdout,"hello, world!\n"); }
#endif