/* Copyright (C) 1996-2000 Ghostgum Software Pty Ltd.  All rights reserved.
  
  This program is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by the
  Free Software Foundation; either version 2 of the License, or (at your
  option) any later version.

  This program is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  General Public License for more details.

  You should have received a copy of the GNU General Public License along
  with this program; if not, write to the Free Software Foundation, Inc.,
  59 Temple Place, Suite 330, Boston, MA, 02111-1307.

*/

/* $Id: dwdll.c,v 1.2.2.1.2.1 2003/01/17 00:49:00 giles Exp $ */

/* dwdll.c */

#define STRICT
#include <windows.h>
#include <string.h>
#include <stdio.h>

#include "stdpre.h"
#include "gpgetenv.h"
#include "gscdefs.h"
#define GSREVISION gs_revision

#define GSDLLEXPORT
#define GSDLLAPI CALLBACK
#define GSDLLCALL

#include "dwdll.h"

static const char name[] = "gsdll32.dll";

int load_dll(GSDLL *gsdll, char *last_error, int len)
{
char fullname[1024];
char *p;
long version;
int length;
gsapi_revision_t rv;

    /* Don't load if already loaded */
    if (gsdll->hmodule)
	return 0;

    /* First try to load DLL from the same directory as EXE */
    GetModuleFileName(GetModuleHandle(NULL), fullname, sizeof(fullname));
    if ((p = strrchr(fullname,'\\')) != (char *)NULL)
	p++;
    else
	p = fullname;
    *p = '\0';
    strcat(fullname, name);
    gsdll->hmodule = LoadLibrary(fullname);

    /* Next try to load DLL with name in registry or environment variable */
    if (gsdll->hmodule < (HINSTANCE)HINSTANCE_ERROR) {
	length = sizeof(fullname);
	if (gp_getenv("GS_DLL", fullname, &length) == 0)
	    gsdll->hmodule = LoadLibrary(fullname);
    }

    /* Finally try the system search path */
    if (gsdll->hmodule < (HINSTANCE)HINSTANCE_ERROR)
        gsdll->hmodule = LoadLibrary(name);

    if (gsdll->hmodule < (HINSTANCE)HINSTANCE_ERROR) {
	/* Failed */
	DWORD err = GetLastError();
	sprintf(fullname, "Can't load DLL, LoadLibrary error code %ld", err);
	strncpy(last_error, fullname, len-1);
	gsdll->hmodule = (HINSTANCE)0;
	return 1;
    }

    /* DLL is now loaded */
    /* Get pointers to functions */
    gsdll->revision = (PFN_gsapi_revision) GetProcAddress(gsdll->hmodule, 
	"gsapi_revision");
    if (gsdll->revision == NULL) {
	strncpy(last_error, "Can't find gsapi_revision\n", len-1);
	unload_dll(gsdll);
	return 1;
    }
    /* check DLL version */
    if (gsdll->revision(&rv, sizeof(rv)) != 0) {
	sprintf(fullname, "Unable to identify Ghostscript DLL revision - it must be newer than needed.\n");
	strncpy(last_error, fullname, len-1);
	unload_dll(gsdll);
	return 1;
    }
    if (rv.revision != GSREVISION) {
	sprintf(fullname, "Wrong version of DLL found.\n  Found version %ld\n  Need version  %ld\n", rv.revision, GSREVISION);
	strncpy(last_error, fullname, len-1);
	unload_dll(gsdll);
	return 1;
    }

    /* continue loading other functions */
    gsdll->new_instance = (PFN_gsapi_new_instance) GetProcAddress(gsdll->hmodule, 
	"gsapi_new_instance");
    if (gsdll->new_instance == NULL) {
	strncpy(last_error, "Can't find gsapi_new_instance\n", len-1);
	unload_dll(gsdll);
	return 1;
    }

    gsdll->delete_instance = (PFN_gsapi_delete_instance) GetProcAddress(gsdll->hmodule, 
	"gsapi_delete_instance");
    if (gsdll->delete_instance == NULL) {
	strncpy(last_error, "Can't find gsapi_delete_instance\n", len-1);
	unload_dll(gsdll);
	return 1;
    }

    gsdll->set_stdio = (PFN_gsapi_set_stdio) GetProcAddress(gsdll->hmodule, 
	"gsapi_set_stdio");
    if (gsdll->set_stdio == NULL) {
	strncpy(last_error, "Can't find gsapi_set_stdio\n", len-1);
	unload_dll(gsdll);
	return 1;
    }

    gsdll->set_poll = (PFN_gsapi_set_poll) GetProcAddress(gsdll->hmodule, 
	"gsapi_set_poll");
    if (gsdll->set_poll == NULL) {
	strncpy(last_error, "Can't find gsapi_set_poll\n", len-1);
	unload_dll(gsdll);
	return 1;
    }

    gsdll->set_display_callback = (PFN_gsapi_set_display_callback) 
	GetProcAddress(gsdll->hmodule, "gsapi_set_display_callback");
    if (gsdll->set_display_callback == NULL) {
	strncpy(last_error, "Can't find gsapi_set_display_callback\n", len-1);
	unload_dll(gsdll);
	return 1;
    }

    gsdll->init_with_args = (PFN_gsapi_init_with_args) 
	GetProcAddress(gsdll->hmodule, "gsapi_init_with_args");
    if (gsdll->init_with_args == NULL) {
	strncpy(last_error, "Can't find gsapi_init_with_args\n", len-1);
	unload_dll(gsdll);
	return 1;
    }

    gsdll->run_string = (PFN_gsapi_run_string) GetProcAddress(gsdll->hmodule, 
	"gsapi_run_string");
    if (gsdll->run_string == NULL) {
	strncpy(last_error, "Can't find gsapi_run_string\n", len-1);
	unload_dll(gsdll);
	return 1;
    }

    gsdll->exit = (PFN_gsapi_exit) GetProcAddress(gsdll->hmodule, 
	"gsapi_exit");
    if (gsdll->exit == NULL) {
	strncpy(last_error, "Can't find gsapi_exit\n", len-1);
	unload_dll(gsdll);
	return 1;
    }

    return 0;
}

void unload_dll(GSDLL *gsdll)
{
    /* Set functions to NULL to prevent use */
    gsdll->revision = NULL;
    gsdll->new_instance = NULL;
    gsdll->delete_instance = NULL;
    gsdll->init_with_args = NULL;
    gsdll->run_string = NULL;
    gsdll->exit = NULL;
    gsdll->set_stdio = NULL;
    gsdll->set_poll = NULL;
    gsdll->set_display_callback = NULL;

    if (gsdll->hmodule != (HINSTANCE)NULL)
	    FreeLibrary(gsdll->hmodule);
    gsdll->hmodule = NULL;
}