diff -Naur genpat3posix.orig/Checksums.cpp genpat3posix/Checksums.cpp
--- genpat3posix.orig/Checksums.cpp	2005-08-20 20:58:50.000000000 +0800
+++ genpat3posix/Checksums.cpp	2005-09-08 12:21:27.000000000 +0800
@@ -23,6 +23,7 @@
 //    misrepresented as being the original software.
 // 3. This notice may not be removed or altered from any source distribution.
 
+#include <stdio.h>
 #include "Checksums.h"
 
 /* ------------------------ CRC32 checksum calculation ----------------- */
@@ -42,7 +43,7 @@
         bInitCRC = TRUE;
 }
 
-BOOL FileCRC(HANDLE hFile, DWORD *crc) {
+BOOL FileCRC(FILE* hFile, DWORD *crc) {
 
         if (bInitCRC == FALSE)
                 InitCRC();
@@ -54,9 +55,11 @@
 
         UINT c = 0xFFFFFFFF;
 
-        SetFilePointer(hFile, 0, NULL, FILE_BEGIN);
+        rewind(hFile);
+        // same as fseek(hFile, 0L, SEEK_SET);
         do {
-                if (ReadFile(hFile, block, CRCBLOCKSIZE, &read, NULL) == FALSE)
+                read = fread( block, 1, CRCBLOCKSIZE, hFile );
+                if ( ferror(hFile) )
                         return FALSE;
                 for (p = block; p < block + read; p++)
                         c = CRCTable[(c & 0xFF) ^ *p] ^ (c >> 8);
@@ -68,15 +71,14 @@
 }
 
 DWORD fileCRC(std::string fileName) {
-  HANDLE hPatch = CreateFile(fileName.c_str(), GENERIC_READ, FILE_SHARE_READ, NULL,
-                                                                          OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
+  FILE* hPatch = fopen(fileName.c_str(), "rb");
 
-  if (hPatch == INVALID_HANDLE_VALUE) {
+  if (hPatch == NULL) {
     throw "Unable to open file for CRC";
   }
   DWORD res;
   FileCRC(hPatch,&res);
-  CloseHandle(hPatch);
+  fclose(hPatch);
   return res;
 }
 
@@ -84,7 +86,7 @@
 
 #define MD5BLOCKSIZE    16384
 
-BOOL FileMD5(HANDLE hFile, md5_byte_t digest[16]) {
+BOOL FileMD5(FILE* hFile, md5_byte_t digest[16]) {
   static BYTE md5block[MD5BLOCKSIZE];
   DWORD read;
 
@@ -92,9 +94,11 @@
 
   md5_init(&state);
 
-  SetFilePointer(hFile, 0, NULL, FILE_BEGIN);
+  rewind(hFile);
+  // same as fseek(hFile, 0L, SEEK_SET);
   do {
-    if (ReadFile(hFile, md5block, MD5BLOCKSIZE, &read, NULL) == FALSE)
+    read = fread( md5block, 1, MD5BLOCKSIZE, hFile );
+    if ( ferror(hFile) )
       return FALSE;
     md5_append(&state, md5block, read);
   } while (read);
@@ -104,14 +108,13 @@
 }
 
 void fileMD5(std::string fileName, md5_byte_t digest[16]) {
-  HANDLE hPatch = CreateFile(fileName.c_str(), GENERIC_READ, FILE_SHARE_READ, NULL,
-                                                                          OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
+  FILE* hPatch = fopen(fileName.c_str(), "rb");
 
-  if (hPatch == INVALID_HANDLE_VALUE) {
+  if (hPatch == NULL) {
     throw "Unable to open file for MD5";
   }
   FileMD5(hPatch,digest);
-  CloseHandle(hPatch);
+  fclose(hPatch);
 }
 
     void TChecksum::loadMD5(md5_byte_t newdigest[16]) {
diff -Naur genpat3posix.orig/Checksums.h genpat3posix/Checksums.h
--- genpat3posix.orig/Checksums.h	2005-08-20 20:58:58.000000000 +0800
+++ genpat3posix/Checksums.h	2005-09-08 11:53:27.000000000 +0800
@@ -27,9 +27,10 @@
   #define Checksums_H
 
   #include <string>
-  #define WIN32_LEAN_AND_MEAN
-  #include <windows.h>
+  //#define WIN32_LEAN_AND_MEAN
+  //#include <windows.h>
   #include "md5.h"
+  #include "POSIXUtil.h"
 
   DWORD fileCRC(std::string fileName);
   void fileMD5(std::string fileName, md5_byte_t digest[16]);
diff -Naur genpat3posix.orig/main.cpp genpat3posix/main.cpp
--- genpat3posix.orig/main.cpp	2005-09-08 01:24:16.000000000 +0800
+++ genpat3posix/main.cpp	2005-09-08 11:51:50.000000000 +0800
@@ -35,7 +35,7 @@
 #include <fstream>
 #include <sstream>
 
-/* // This is a POSIX version of the function, together with #include <stdio.h>
+   // This is a POSIX version of the function, together with #include <stdio.h>
    // but I will not add it in a final release version.
 string getTempFile() {
   char filebuf [L_tmpnam];
@@ -48,7 +48,7 @@
 
   return string(fname);
 }
-*/
+/*
 string getTempFile() {
   char buffer[MAX_PATH];
   if(GetTempFileName(".","vpatch",0,buffer) == 0) {
@@ -56,7 +56,7 @@
   }
   return string(buffer);
 }
-
+*/
 int main( int argc, char * argv[] ) {
   cout << "GenPat v3.0 POSIX\n";
   cout << "===========\n\n(c) 2001-2005 Van de Sande Productions\n";
@@ -224,7 +224,7 @@
     } catch(char* s) {
       cerr << "ERROR: " << s << "\n";
       patch.close();
-      DeleteFile(tempFileName.c_str());
+      unlink(tempFileName.c_str());
       return 3;
     }
 
@@ -321,6 +321,6 @@
     cerr << "WARNING: source and target file have equal CRCs!";
   delete sourceCRC;
   delete targetCRC;
-  DeleteFile(tempFileName.c_str());
+  unlink(tempFileName.c_str());
   return 0;
 }
diff -Naur genpat3posix.orig/Makefile genpat3posix/Makefile
--- genpat3posix.orig/Makefile	1970-01-01 08:00:00.000000000 +0800
+++ genpat3posix/Makefile	2005-09-08 12:26:13.000000000 +0800
@@ -0,0 +1,9 @@
+# GNU/Linux Makefile
+
+CXXFLAGS=-Wall
+
+genpat: Checksums.o adler32.o ChunkedFile.o GlobalTypes.o FileFormat1.o main.o md5.o POSIXUtil.o
+	g++ -o $@ $^
+
+clean:
+	rm genpat *.o
diff -Naur genpat3posix.orig/POSIXUtil.cpp genpat3posix/POSIXUtil.cpp
--- genpat3posix.orig/POSIXUtil.cpp	2005-09-08 01:26:40.000000000 +0800
+++ genpat3posix/POSIXUtil.cpp	2005-09-08 11:52:18.000000000 +0800
@@ -25,14 +25,14 @@
 
 
 #include "POSIXUtil.h"
-#include <windows.h>
+//#include <windows.h>
 #include <iostream>
 #include <fstream>
 
 #include <time.h>
 #include <sys/types.h>
 #include <sys/stat.h>
-//#include <unistd.h>
+#include <unistd.h>
 
 int stat(const char *file_name, struct stat *buf);
 int lstat(const char *file_name, struct stat *buf);
diff -Naur genpat3posix.orig/POSIXUtil.h genpat3posix/POSIXUtil.h
--- genpat3posix.orig/POSIXUtil.h	2005-09-07 19:08:32.000000000 +0800
+++ genpat3posix/POSIXUtil.h	2005-09-08 11:54:36.000000000 +0800
@@ -37,4 +37,12 @@
     uint32_t getFileSize(const char* sFileName);
   }
 
+  typedef uint32_t DWORD;
+  typedef uint8_t BYTE;
+  typedef unsigned int UINT;
+  typedef bool BOOL;
+  #define FALSE false
+  #define TRUE true
+  typedef void* HANDLE;
+
 #endif // POSIXUtil_H