/* Copyright (C) 1996-2000 Ghostgum Software Pty Ltd.  All rights reserved.
  
  This software is provided AS-IS with no warranty, either express or
  implied.
  
  This software is distributed under license and may not be copied,
  modified or distributed except as expressly authorized under the terms
  of the license contained in the file LICENSE in this distribution.
  
  For more information about licensing, please refer to
  http://www.ghostscript.com/licensing/. For information on
  commercial licensing, go to http://www.artifex.com/licensing/ or
  contact Artifex Software, Inc., 101 Lucas Valley Road #110,
  San Rafael, CA  94903, U.S.A., +1(415)492-9861.
*/

/* $Id: dwdll.c,v 1.7 2004/04/08 16:18:25 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;
    }

    gsdll->set_visual_tracer = (PFN_gsapi_set_visual_tracer) 
        GetProcAddress(gsdll->hmodule, "gsapi_set_visual_tracer");
    if (gsdll->set_visual_tracer == NULL) {
	strncpy(last_error, "Can't find gsapi_set_visual_tracer\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;
    gsdll->set_visual_tracer = NULL;

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