ssl_applink.h

/*  Part of SWI-Prolog

    Author:        Jan Wielemaker
    E-mail:        jan@swi-prolog.org
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
This file is a work  around  for   the  Windows  CRT  weirdness. The CRT
library can operate in two modes: shared over   the app or local to each
plugin. In the latter  case,  CRT  handles   such  as  FILE*  cannot  be
transferred between DLLs.

OpenSSL provides `<openssl/applink.c>`, which defines OPENSSL_Applink(),
that returns an array of function pointers  for the stdio functions used
by OpenSSL. This must be part of the main executable.

This module figures out wether that is   the  case and redefines fopen()
and fclose() in case it is such  that   we  get the CRT handles from the
right module.
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */

#include <config.h>

#ifdef HAVE_OPENSSL_APPLINK_C
#define APPMACROS_ONLY 1
#include <openssl/applink.c>

static int applink_done = FALSE;
static void **applink_table = NULL;

static void*
applink(int n)
{ if ( !applink_done )
  { HMODULE mod = GetModuleHandle(NULL);
    void**(*f)(void) = (void*)GetProcAddress(mod, "OPENSSL_Applink");
    if ( f )
      applink_table = f();
    applink_done = TRUE;
  }

  if ( applink_table )
    return applink_table[n];
  else
    return NULL;
}

static inline FILE*
app_fopen(const char *name, const char *mode)
{ FILE*(*f_fopen)(const char*, const char*) = applink(APPLINK_FOPEN);

  return f_fopen ? f_fopen(name, mode) : fopen(name, mode);
}

static inline int
app_fclose(FILE *fp)
{ int(*f_fclose)(FILE*) = applink(APPLINK_FCLOSE);

  return f_fclose ? f_fclose(fp) : fclose(fp);
}

#define fopen(name,mode)	app_fopen(name,mode)
#define fclose(fp)		app_fclose(fp)

#endif /*HAVE_OPENSSL_APPLINK_C*/