Unlink temp file after loading on POSIX.

* Unlink the temporary library file after the last file descriptor to it is opened (`System.load(temp.getAbsolutePath())`) on systems that appear to be POSIX compliant.

src/main/java/cz/adamh/utils/NativeUtils.java

@@ -24,7 +24,11 @@
 package cz.adamh.utils;
 
 import java.io.*;
- 
+import java.net.URI;
+import java.nio.file.FileSystemNotFoundException;
+import java.nio.file.FileSystems;
+import java.nio.file.ProviderNotFoundException;
+
 /**
  * A simple library class which helps with loading dynamic libraries stored in the
  * JAR archive. These libraries usualy contain implementation of some methods in
@@ -79,35 +83,59 @@ public class NativeUtils {
  
         // Prepare temporary file
         File temp = File.createTempFile(prefix, suffix);
-        temp.deleteOnExit();
- 
+
         if (!temp.exists()) {
             throw new FileNotFoundException("File " + temp.getAbsolutePath() + " does not exist.");
         }
- 
+
+        boolean tempFileIsPosix = false;
+        try {
+            if (FileSystems.getDefault()
+                    .supportedFileAttributeViews()
+                    .contains("posix")) {
+                // Assume POSIX compliant file system, can be deleted after loading.
+                tempFileIsPosix = true;
+            }
+        } catch (FileSystemNotFoundException
+                | ProviderNotFoundException
+                | SecurityException e) {
+            // Assume non-POSIX, and don't delete until last file descriptor closed.
+        }
+
         // Prepare buffer for data copying
         byte[] buffer = new byte[1024];
         int readBytes;
- 
+
         // Open and check input stream
         InputStream is = NativeUtils.class.getResourceAsStream(path);
         if (is == null) {
+            temp.delete();
             throw new FileNotFoundException("File " + path + " was not found inside JAR.");
         }
- 
+
         // Open output stream and copy data between source file in JAR and the temporary file
         OutputStream os = new FileOutputStream(temp);
         try {
             while ((readBytes = is.read(buffer)) != -1) {
                 os.write(buffer, 0, readBytes);
             }
+        } catch (Exception e) {
+            temp.delete();
+            throw e;
         } finally {
             // If read/write fails, close streams safely before throwing an exception
             os.close();
             is.close();
         }
- 
-        // Finally, load the library
-        System.load(temp.getAbsolutePath());
+
+        try {
+            // Load the library
+            System.load(temp.getAbsolutePath());
+        } finally {
+            if (tempFileIsPosix)
+                temp.delete();
+            else
+                temp.deleteOnExit();
+        }
     }
 }