openssl/crypto/dso/dso_win32.c

/* dso_win32.c -*- mode:C; c-file-style: "eay" -*- */
/* Written by Geoff Thorpe (geoff@geoffthorpe.net) for the OpenSSL
 * project 2000.
 */
/* ====================================================================
 * Copyright (c) 2000 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

#include <stdio.h>
#include <string.h>
#include "cryptlib.h"
#include <openssl/dso.h>

#if !defined(DSO_WIN32)
DSO_METHOD *DSO_METHOD_win32(void)
	{
	return NULL;
	}
#else

#ifdef _WIN32_WCE
# if _WIN32_WCE < 300
static FARPROC GetProcAddressA(HMODULE hModule,LPCSTR lpProcName)
	{
	WCHAR lpProcNameW[64];
	int i;

	for (i=0;lpProcName[i] && i<64;i++)
		lpProcNameW[i] = (WCHAR)lpProcName[i];
	if (i==64) return NULL;
	lpProcNameW[i] = 0;

	return GetProcAddressW(hModule,lpProcNameW);
	}
# endif
# undef GetProcAddress
# define GetProcAddress GetProcAddressA

static HINSTANCE LoadLibraryA(LPCSTR lpLibFileName)
	{
	WCHAR *fnamw;
	size_t len_0=strlen(lpLibFileName)+1,i;

#ifdef _MSC_VER
	fnamw = (WCHAR *)_alloca (len_0*sizeof(WCHAR));
#else
	fnamw = (WCHAR *)alloca (len_0*sizeof(WCHAR));
#endif
	if (fnamw == NULL)
		{
		SetLastError(ERROR_NOT_ENOUGH_MEMORY);
		return NULL;
		}

#if defined(_WIN32_WCE) && _WIN32_WCE>=101
	if (!MultiByteToWideChar(CP_ACP,0,lpLibFileName,len_0,fnamw,len_0))
#endif
		for (i=0;i<len_0;i++) fnamw[i]=(WCHAR)lpLibFileName[i];

	return LoadLibraryW(fnamw);
	}
#endif

/* Part of the hack in "win32_load" ... */
#define DSO_MAX_TRANSLATED_SIZE 256

static int win32_load(DSO *dso);
static int win32_unload(DSO *dso);
static void *win32_bind_var(DSO *dso, const char *symname);
static DSO_FUNC_TYPE win32_bind_func(DSO *dso, const char *symname);
#if 0
static int win32_unbind_var(DSO *dso, char *symname, void *symptr);
static int win32_unbind_func(DSO *dso, char *symname, DSO_FUNC_TYPE symptr);
static int win32_init(DSO *dso);
static int win32_finish(DSO *dso);
static long win32_ctrl(DSO *dso, int cmd, long larg, void *parg);
#endif
static char *win32_name_converter(DSO *dso, const char *filename);
static char *win32_merger(DSO *dso, const char *filespec1,
	const char *filespec2);
static int win32_pathbyaddr(void *addr,char *path,int sz);
static DSO_FUNC_TYPE win32_globallookup(const char *name);

static const char *openssl_strnchr(const char *string, int c, size_t len);

static DSO_METHOD dso_meth_win32 = {
	"OpenSSL 'win32' shared library method",
	win32_load,
	win32_unload,
	win32_bind_var,
	win32_bind_func,
/* For now, "unbind" doesn't exist */
#if 0
	NULL, /* unbind_var */
	NULL, /* unbind_func */
#endif
	NULL, /* ctrl */
	win32_name_converter,
	win32_merger,
	NULL, /* init */
	NULL, /* finish */
	win32_pathbyaddr,
	win32_globallookup
	};

DSO_METHOD *DSO_METHOD_win32(void)
	{
	return(&dso_meth_win32);
	}

/* For this DSO_METHOD, our meth_data STACK will contain;
 * (i) a pointer to the handle (HINSTANCE) returned from
 *     LoadLibrary(), and copied.
 */

static int win32_load(DSO *dso)
	{
	HINSTANCE h = NULL, *p = NULL;
	/* See applicable comments from dso_dl.c */
	char *filename = DSO_convert_filename(dso, NULL);

	if(filename == NULL)
		{
		DSOerr(DSO_F_WIN32_LOAD,DSO_R_NO_FILENAME);
		goto err;
		}
	h = LoadLibraryA(filename);
	if(h == NULL)
		{
		DSOerr(DSO_F_WIN32_LOAD,DSO_R_LOAD_FAILED);
		ERR_add_error_data(3, "filename(", filename, ")");
		goto err;
		}
	p = (HINSTANCE *)OPENSSL_malloc(sizeof(HINSTANCE));
	if(p == NULL)
		{
		DSOerr(DSO_F_WIN32_LOAD,ERR_R_MALLOC_FAILURE);
		goto err;
		}
	*p = h;
	if(!sk_push(dso->meth_data, (char *)p))
		{
		DSOerr(DSO_F_WIN32_LOAD,DSO_R_STACK_ERROR);
		goto err;
		}
	/* Success */
	dso->loaded_filename = filename;
	return(1);
err:
	/* Cleanup !*/
	if(filename != NULL)
		OPENSSL_free(filename);
	if(p != NULL)
		OPENSSL_free(p);
	if(h != NULL)
		FreeLibrary(h);
	return(0);
	}

static int win32_unload(DSO *dso)
	{
	HINSTANCE *p;
	if(dso == NULL)
		{
		DSOerr(DSO_F_WIN32_UNLOAD,ERR_R_PASSED_NULL_PARAMETER);
		return(0);
		}
	if(sk_num(dso->meth_data) < 1)
		return(1);
	p = (HINSTANCE *)sk_pop(dso->meth_data);
	if(p == NULL)
		{
		DSOerr(DSO_F_WIN32_UNLOAD,DSO_R_NULL_HANDLE);
		return(0);
		}
	if(!FreeLibrary(*p))
		{
		DSOerr(DSO_F_WIN32_UNLOAD,DSO_R_UNLOAD_FAILED);
		/* We should push the value back onto the stack in
		 * case of a retry. */
		sk_push(dso->meth_data, (char *)p);
		return(0);
		}
	/* Cleanup */
	OPENSSL_free(p);
	return(1);
	}

/* Using GetProcAddress for variables? TODO: Check this out in
 * the Win32 API docs, there's probably a variant for variables. */
static void *win32_bind_var(DSO *dso, const char *symname)
	{
	HINSTANCE *ptr;
	void *sym;

	if((dso == NULL) || (symname == NULL))
		{
		DSOerr(DSO_F_WIN32_BIND_VAR,ERR_R_PASSED_NULL_PARAMETER);
		return(NULL);
		}
	if(sk_num(dso->meth_data) < 1)
		{
		DSOerr(DSO_F_WIN32_BIND_VAR,DSO_R_STACK_ERROR);
		return(NULL);
		}
	ptr = (HINSTANCE *)sk_value(dso->meth_data, sk_num(dso->meth_data) - 1);
	if(ptr == NULL)
		{
		DSOerr(DSO_F_WIN32_BIND_VAR,DSO_R_NULL_HANDLE);
		return(NULL);
		}
	sym = GetProcAddress(*ptr, symname);
	if(sym == NULL)
		{
		DSOerr(DSO_F_WIN32_BIND_VAR,DSO_R_SYM_FAILURE);
		ERR_add_error_data(3, "symname(", symname, ")");
		return(NULL);
		}
	return(sym);
	}

static DSO_FUNC_TYPE win32_bind_func(DSO *dso, const char *symname)
	{
	HINSTANCE *ptr;
	void *sym;

	if((dso == NULL) || (symname == NULL))
		{
		DSOerr(DSO_F_WIN32_BIND_FUNC,ERR_R_PASSED_NULL_PARAMETER);
		return(NULL);
		}
	if(sk_num(dso->meth_data) < 1)
		{
		DSOerr(DSO_F_WIN32_BIND_FUNC,DSO_R_STACK_ERROR);
		return(NULL);
		}
	ptr = (HINSTANCE *)sk_value(dso->meth_data, sk_num(dso->meth_data) - 1);
	if(ptr == NULL)
		{
		DSOerr(DSO_F_WIN32_BIND_FUNC,DSO_R_NULL_HANDLE);
		return(NULL);
		}
	sym = GetProcAddress(*ptr, symname);
	if(sym == NULL)
		{
		DSOerr(DSO_F_WIN32_BIND_FUNC,DSO_R_SYM_FAILURE);
		ERR_add_error_data(3, "symname(", symname, ")");
		return(NULL);
		}
	return((DSO_FUNC_TYPE)sym);
	}

struct file_st
	{
	const char *node; int nodelen;
	const char *device; int devicelen;
	const char *predir; int predirlen;
	const char *dir; int dirlen;
	const char *file; int filelen;
	};

static struct file_st *win32_splitter(DSO *dso, const char *filename,
	int assume_last_is_dir)
	{
	struct file_st *result = NULL;
	enum { IN_NODE, IN_DEVICE, IN_FILE } position;
	const char *start = filename;
	char last;

	if (!filename)
		{
		DSOerr(DSO_F_WIN32_SPLITTER,DSO_R_NO_FILENAME);
		/*goto err;*/
		return(NULL);
		}

	result = OPENSSL_malloc(sizeof(struct file_st));
	if(result == NULL)
		{
		DSOerr(DSO_F_WIN32_SPLITTER,
			ERR_R_MALLOC_FAILURE);
		return(NULL);
		}

	memset(result, 0, sizeof(struct file_st));
	position = IN_DEVICE;

	if((filename[0] == '\\' && filename[1] == '\\')
		|| (filename[0] == '/' && filename[1] == '/'))
		{
		position = IN_NODE;
		filename += 2;
		start = filename;
		result->node = start;
		}

	do
		{
		last = filename[0];
		switch(last)
			{
		case ':':
			if(position != IN_DEVICE)
				{
				DSOerr(DSO_F_WIN32_SPLITTER,
					DSO_R_INCORRECT_FILE_SYNTAX);
				/*goto err;*/
				return(NULL);
				}
			result->device = start;
			result->devicelen = filename - start;
			position = IN_FILE;
			start = ++filename;
			result->dir = start;
			break;
		case '\\':
		case '/':
			if(position == IN_NODE)
				{
				result->nodelen = filename - start;
				position = IN_FILE;
				start = ++filename;
				result->dir = start;
				}
			else if(position == IN_DEVICE)
				{
				position = IN_FILE;
				filename++;
				result->dir = start;
				result->dirlen = filename - start;
				start = filename;
				}
			else
				{
				filename++;
				result->dirlen += filename - start;
				start = filename;
				}
			break;
		case '\0':
			if(position == IN_NODE)
				{
				result->nodelen = filename - start;
				}
			else
				{
				if(filename - start > 0)
					{
					if (assume_last_is_dir)
						{
						if (position == IN_DEVICE)
							{
							result->dir = start;
							result->dirlen = 0;
							}
						result->dirlen +=
							filename - start;
						}
					else
						{
						result->file = start;
						result->filelen =
							filename - start;
						}
					}
				}
			break;
		default:
			filename++;
			break;
			}
		}
	while(last);

	if(!result->nodelen) result->node = NULL;
	if(!result->devicelen) result->device = NULL;
	if(!result->dirlen) result->dir = NULL;
	if(!result->filelen) result->file = NULL;

	return(result);
	}

static char *win32_joiner(DSO *dso, const struct file_st *file_split)
	{
	int len = 0, offset = 0;
	char *result = NULL;
	const char *start;

	if(!file_split)
		{
		DSOerr(DSO_F_WIN32_JOINER,
				ERR_R_PASSED_NULL_PARAMETER);
		return(NULL);
		}
	if(file_split->node)
		{
		len += 2 + file_split->nodelen;	/* 2 for starting \\ */
		if(file_split->predir || file_split->dir || file_split->file)
			len++;	/* 1 for ending \ */
		}
	else if(file_split->device)
		{
		len += file_split->devicelen + 1; /* 1 for ending : */
		}
	len += file_split->predirlen;
	if(file_split->predir && (file_split->dir || file_split->file))
		{
		len++;	/* 1 for ending \ */
		}
	len += file_split->dirlen;
	if(file_split->dir && file_split->file)
		{
		len++;	/* 1 for ending \ */
		}
	len += file_split->filelen;

	if(!len)
		{
		DSOerr(DSO_F_WIN32_JOINER, DSO_R_EMPTY_FILE_STRUCTURE);
		return(NULL);
		}

	result = OPENSSL_malloc(len + 1);
	if (!result)
		{
		DSOerr(DSO_F_WIN32_JOINER,
			ERR_R_MALLOC_FAILURE);
		return(NULL);
		}

	if(file_split->node)
		{
		strcpy(&result[offset], "\\\\"); offset += 2;
		strncpy(&result[offset], file_split->node,
			file_split->nodelen); offset += file_split->nodelen;
		if(file_split->predir || file_split->dir || file_split->file)
			{
			result[offset] = '\\'; offset++;
			}
		}
	else if(file_split->device)
		{
		strncpy(&result[offset], file_split->device,
			file_split->devicelen); offset += file_split->devicelen;
		result[offset] = ':'; offset++;
		}
	start = file_split->predir;
	while(file_split->predirlen > (start - file_split->predir))
		{
		const char *end = openssl_strnchr(start, '/',
			file_split->predirlen - (start - file_split->predir));
		if(!end)
			end = start
				+ file_split->predirlen
				- (start - file_split->predir);
		strncpy(&result[offset], start,
			end - start); offset += end - start;
		result[offset] = '\\'; offset++;
		start = end + 1;
		}
#if 0 /* Not needed, since the directory converter above already appeneded
	 a backslash */
	if(file_split->predir && (file_split->dir || file_split->file))
		{
		result[offset] = '\\'; offset++;
		}
#endif
	start = file_split->dir;
	while(file_split->dirlen > (start - file_split->dir))
		{
		const char *end = openssl_strnchr(start, '/',
			file_split->dirlen - (start - file_split->dir));
		if(!end)
			end = start
				+ file_split->dirlen
				- (start - file_split->dir);
		strncpy(&result[offset], start,
			end - start); offset += end - start;
		result[offset] = '\\'; offset++;
		start = end + 1;
		}
#if 0 /* Not needed, since the directory converter above already appeneded
	 a backslash */
	if(file_split->dir && file_split->file)
		{
		result[offset] = '\\'; offset++;
		}
#endif
	strncpy(&result[offset], file_split->file,
		file_split->filelen); offset += file_split->filelen;
	result[offset] = '\0';
	return(result);
	}

static char *win32_merger(DSO *dso, const char *filespec1, const char *filespec2)
	{
	char *merged = NULL;
	struct file_st *filespec1_split = NULL;
	struct file_st *filespec2_split = NULL;

	if(!filespec1 && !filespec2)
		{
		DSOerr(DSO_F_WIN32_MERGER,
				ERR_R_PASSED_NULL_PARAMETER);
		return(NULL);
		}
	if (!filespec2)
		{
		merged = OPENSSL_malloc(strlen(filespec1) + 1);
		if(!merged)
			{
			DSOerr(DSO_F_WIN32_MERGER,
				ERR_R_MALLOC_FAILURE);
			return(NULL);
			}
		strcpy(merged, filespec1);
		}
	else if (!filespec1)
		{
		merged = OPENSSL_malloc(strlen(filespec2) + 1);
		if(!merged)
			{
			DSOerr(DSO_F_WIN32_MERGER,
				ERR_R_MALLOC_FAILURE);
			return(NULL);
			}
		strcpy(merged, filespec2);
		}
	else
		{
		filespec1_split = win32_splitter(dso, filespec1, 1);
		if (!filespec1_split)
			{
			DSOerr(DSO_F_WIN32_MERGER,
				ERR_R_MALLOC_FAILURE);
			return(NULL);
			}
		filespec2_split = win32_splitter(dso, filespec2, 0);
		if (!filespec2_split)
			{
			DSOerr(DSO_F_WIN32_MERGER,
				ERR_R_MALLOC_FAILURE);
			OPENSSL_free(filespec1_split);
			return(NULL);
			}

		/* Fill in into filespec1_split */
		if (!filespec1_split->node && !filespec1_split->device)
			{
			filespec1_split->node = filespec2_split->node;
			filespec1_split->nodelen = filespec2_split->nodelen;
			filespec1_split->device = filespec2_split->device;
			filespec1_split->devicelen = filespec2_split->devicelen;
			}
		if (!filespec1_split->dir)
			{
			filespec1_split->dir = filespec2_split->dir;
			filespec1_split->dirlen = filespec2_split->dirlen;
			}
		else if (filespec1_split->dir[0] != '\\'
			&& filespec1_split->dir[0] != '/')
			{
			filespec1_split->predir = filespec2_split->dir;
			filespec1_split->predirlen = filespec2_split->dirlen;
			}
		if (!filespec1_split->file)
			{
			filespec1_split->file = filespec2_split->file;
			filespec1_split->filelen = filespec2_split->filelen;
			}

		merged = win32_joiner(dso, filespec1_split);
		}
	return(merged);
	}

static char *win32_name_converter(DSO *dso, const char *filename)
	{
	char *translated;
	int len, transform;

	len = strlen(filename);
	transform = ((strstr(filename, "/") == NULL) &&
			(strstr(filename, "\\") == NULL) &&
			(strstr(filename, ":") == NULL));
	if(transform)
		/* We will convert this to "%s.dll" */
		translated = OPENSSL_malloc(len + 5);
	else
		/* We will simply duplicate filename */
		translated = OPENSSL_malloc(len + 1);
	if(translated == NULL)
		{
		DSOerr(DSO_F_WIN32_NAME_CONVERTER,
				DSO_R_NAME_TRANSLATION_FAILED); 
		return(NULL);   
		}
	if(transform)
		sprintf(translated, "%s.dll", filename);
	else
		sprintf(translated, "%s", filename);
	return(translated);
	}

static const char *openssl_strnchr(const char *string, int c, size_t len)
	{
	size_t i;
	const char *p;
	for (i = 0, p = string; i < len && *p; i++, p++)
		{
		if (*p == c)
			return p;
		}
	return NULL;
	}

#include <tlhelp32.h>
#ifdef _WIN32_WCE
# define DLLNAME "TOOLHELP.DLL"
#else
# ifdef MODULEENTRY32
# undef MODULEENTRY32	/* unmask the ASCII version! */
# endif
# define DLLNAME "KERNEL32.DLL"
#endif

typedef HANDLE (WINAPI *CREATETOOLHELP32SNAPSHOT)(DWORD, DWORD);
typedef BOOL (WINAPI *CLOSETOOLHELP32SNAPSHOT)(HANDLE);
typedef BOOL (WINAPI *MODULE32)(HANDLE, MODULEENTRY32 *);

static int win32_pathbyaddr(void *addr,char *path,int sz)
	{
	HMODULE dll;
	HANDLE hModuleSnap = INVALID_HANDLE_VALUE; 
	MODULEENTRY32 me32; 
	CREATETOOLHELP32SNAPSHOT create_snap;
	CLOSETOOLHELP32SNAPSHOT  close_snap;
	MODULE32 module_first, module_next;
	int len;
 
	if (addr == NULL)
		{
		union	{ int(*f)(void*,char*,int); void *p; } t =
			{ win32_pathbyaddr };
		addr = t.p;
		}

	dll = LoadLibrary(TEXT(DLLNAME));
	if (dll == NULL)
		{
		DSOerr(DSO_F_PATHBYADDR,DSO_R_UNSUPPORTED);
		return -1;
		}

	create_snap = (CREATETOOLHELP32SNAPSHOT)
		GetProcAddress(dll,"CreateToolhelp32Snapshot");
	if (create_snap == NULL)
		{
		FreeLibrary(dll);
		DSOerr(DSO_F_PATHBYADDR,DSO_R_UNSUPPORTED);
		return -1;
		}
	/* We take the rest for granted... */
#ifdef _WIN32_WCE
	close_snap = (CLOSETOOLHELP32SNAPSHOT)
		GetProcAddress(dll,"CloseToolhelp32Snapshot");
#else
	close_snap = (CLOSETOOLHELP32SNAPSHOT)CloseHandle;
#endif
	module_first = (MODULE32)GetProcAddress(dll,"Module32First");
	module_next  = (MODULE32)GetProcAddress(dll,"Module32Next");

	hModuleSnap = (*create_snap)(TH32CS_SNAPMODULE,0); 
	if( hModuleSnap == INVALID_HANDLE_VALUE ) 
		{ 
		FreeLibrary(dll);
		DSOerr(DSO_F_PATHBYADDR,DSO_R_UNSUPPORTED);
		return -1;
		} 
 
	me32.dwSize = sizeof(me32); 
 
	if(!(*module_first)(hModuleSnap,&me32)) 
		{ 
		(*close_snap)(hModuleSnap);
		FreeLibrary(dll);
		DSOerr(DSO_F_PATHBYADDR,DSO_R_FAILURE);
		return -1;
		}
 
	do	{ 
		if ((BYTE *)addr >= me32.modBaseAddr &&
		    (BYTE *)addr <  me32.modBaseAddr+me32.modBaseSize)
			{
			(*close_snap)(hModuleSnap);
			FreeLibrary(dll);
#ifdef _WIN32_WCE
# if _WIN32_WCE >= 101
			return WideCharToMultiByte(CP_ACP,0,me32.szExePath,-1,
							path,sz,NULL,NULL);
# else
			len = (int)wcslen(me32.szExePath);
			if (sz <= 0) return len+1;
			if (len >= sz) len=sz-1;
			for(i=0;i<len;i++)
				path[i] = (char)me32.szExePath[i];
			path[len++] = 0;
			return len;
# endif
#else
			len = (int)strlen(me32.szExePath);
			if (sz <= 0) return len+1;
			if (len >= sz) len=sz-1;
			memcpy(path,me32.szExePath,len);
			path[len++] = 0;
			return len;
#endif
			} 
		} while((*module_next)(hModuleSnap, &me32)); 
 
	(*close_snap)(hModuleSnap); 
	FreeLibrary(dll);
	return 0;
	}

static DSO_FUNC_TYPE win32_globallookup(const char *name)
	{
	HMODULE dll;
	HANDLE hModuleSnap = INVALID_HANDLE_VALUE;
	MODULEENTRY32 me32;
	CREATETOOLHELP32SNAPSHOT create_snap;
	CLOSETOOLHELP32SNAPSHOT  close_snap;
	MODULE32 module_first, module_next;
	FARPROC ret=NULL;

	dll = LoadLibrary(TEXT(DLLNAME));
	if (dll == NULL)
		{
		DSOerr(DSO_F_GLOBAL_LOOKUP_FUNC,DSO_R_UNSUPPORTED);
		return NULL;
		}

	create_snap = (CREATETOOLHELP32SNAPSHOT)
		GetProcAddress(dll,"CreateToolhelp32Snapshot");
	if (create_snap == NULL)
		{
		FreeLibrary(dll);
		DSOerr(DSO_F_GLOBAL_LOOKUP_FUNC,DSO_R_UNSUPPORTED);
		return NULL;
		}
	/* We take the rest for granted... */
#ifdef _WIN32_WCE
	close_snap = (CLOSETOOLHELP32SNAPSHOT)
		GetProcAddress(dll,"CloseToolhelp32Snapshot");
#else
	close_snap = (CLOSETOOLHELP32SNAPSHOT)CloseHandle;
#endif
	module_first = (MODULE32)GetProcAddress(dll,"Module32First");
	module_next  = (MODULE32)GetProcAddress(dll,"Module32Next");

	hModuleSnap = (*create_snap)(TH32CS_SNAPMODULE,0);
	if( hModuleSnap == INVALID_HANDLE_VALUE ) return NULL;

	me32.dwSize = sizeof(me32);

	if (!(*module_first)(hModuleSnap,&me32))
		{
		(*close_snap)(hModuleSnap);
		FreeLibrary(dll);
		return NULL;
		}

	do	{
		if (ret = GetProcAddress(me32.hModule,fname))
			{
			(*close_snap)(hModuleSnap);
			FreeLibrary(dll);
			return ret;
			}
		} while((*module_next)(hModuleSnap,&me32));

	(*close_snap)(hModuleSnap); 
	FreeLibrary(dll);
	return NULL;
	}
#endif /* DSO_WIN32 */