Add c.s.j.p.bsd.ExtAttr and c.s.j.p.bsd.ExtAttrUtil to wrap BSD <sys/extattr.h> system calls

Author: rednoah

CHANGES.md

@@ -10,6 +10,7 @@ Features
 * [#1534](https://github.com/java-native-access/jna/pull/1534): Add `GetMethod`, `Put`, `SpawnInstance` to `c.s.j.p.win32.COM.WbemCli#IWbemClassObject` and `ExecMethod` to `c.s.j.p.win32.COM.WbemCli#IWbemServices` - [@faddom](https://github.com/faddom).
 * [#1544](https://github.com/java-native-access/jna/pull/1544): Add `GetPriorityClass`, `SetPriorityClass`, `GetThreadPriority`, `SetThreadPriority` and associated constants to `c.s.j.p.win32.Kernel32` - [@dEajL3kA](https://github.com/dEajL3kA).
 * [#1548](https://github.com/java-native-access/jna/pull/1548): Make interface `c.s.j.p.mac.XAttr public` - [@matthiasblaesing](https://github.com/matthiasblaesing).
+* [#1551](https://github.com/java-native-access/jna/pull/1549): Add `c.s.j.p.bsd.ExtAttr` and `c.s.j.p.bsd.ExtAttrUtil` to wrap BSD [<sys/extattr.h>](https://man.freebsd.org/cgi/man.cgi?query=extattr&sektion=2) system calls. [@rednoah](https://github.com/rednoah).
 
 Bug Fixes
 ---------

contrib/platform/src/com/sun/jna/platform/bsd/ExtAttr.java

@@ -0,0 +1,47 @@
+/* Copyright (c) 2023 Reinhard Pointner, All Rights Reserved
+ *
+ * The contents of this file is dual-licensed under 2
+ * alternative Open Source/Free licenses: LGPL 2.1 or later and
+ * Apache License 2.0. (starting with JNA version 4.0.0).
+ *
+ * You can freely decide which license you want to apply to
+ * the project.
+ *
+ * You may obtain a copy of the LGPL License at:
+ *
+ * http://www.gnu.org/licenses/licenses.html
+ *
+ * A copy is also included in the downloadable source code package
+ * containing JNA, in file "LGPL2.1".
+ *
+ * You may obtain a copy of the Apache License at:
+ *
+ * http://www.apache.org/licenses/
+ *
+ * A copy is also included in the downloadable source code package
+ * containing JNA, in file "AL2.0".
+ */
+package com.sun.jna.platform.bsd;
+
+import java.nio.ByteBuffer;
+
+import com.sun.jna.Library;
+import com.sun.jna.Native;
+import com.sun.jna.platform.unix.LibCAPI.size_t;
+import com.sun.jna.platform.unix.LibCAPI.ssize_t;
+
+public interface ExtAttr extends Library {
+
+    ExtAttr INSTANCE = Native.load(null, ExtAttr.class);
+
+    int EXTATTR_NAMESPACE_USER = 0x1;
+
+    ssize_t extattr_get_file(String path, int attrnamespace, String attrname, ByteBuffer data, size_t nbytes);
+
+    ssize_t extattr_set_file(String path, int attrnamespace, String attrname, ByteBuffer data, size_t nbytes);
+
+    int extattr_delete_file(String path, int attrnamespace, String attrname);
+
+    ssize_t extattr_list_file(String path, int attrnamespace, ByteBuffer data, size_t nbytes);
+
+}

contrib/platform/src/com/sun/jna/platform/bsd/ExtAttrUtil.java

@@ -0,0 +1,115 @@
+/* Copyright (c) 2023 Reinhard Pointner, All Rights Reserved
+ *
+ * The contents of this file is dual-licensed under 2
+ * alternative Open Source/Free licenses: LGPL 2.1 or later and
+ * Apache License 2.0. (starting with JNA version 4.0.0).
+ *
+ * You can freely decide which license you want to apply to
+ * the project.
+ *
+ * You may obtain a copy of the LGPL License at:
+ *
+ * http://www.gnu.org/licenses/licenses.html
+ *
+ * A copy is also included in the downloadable source code package
+ * containing JNA, in file "LGPL2.1".
+ *
+ * You may obtain a copy of the Apache License at:
+ *
+ * http://www.apache.org/licenses/
+ *
+ * A copy is also included in the downloadable source code package
+ * containing JNA, in file "AL2.0".
+ */
+package com.sun.jna.platform.bsd;
+
+import static java.util.Collections.*;
+
+import java.io.IOException;
+import java.io.UnsupportedEncodingException;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.List;
+
+import com.sun.jna.Native;
+import com.sun.jna.platform.unix.LibCAPI.size_t;
+
+public class ExtAttrUtil {
+
+    public static List<String> list(String path) throws IOException {
+        // get required buffer size
+        long bufferLength = ExtAttr.INSTANCE.extattr_list_file(path, ExtAttr.EXTATTR_NAMESPACE_USER, null, new size_t(0)).longValue();
+
+        if (bufferLength < 0) {
+            throw new IOException("errno: " + Native.getLastError());
+        }
+
+        if (bufferLength == 0) {
+            return emptyList();
+        }
+
+        ByteBuffer buffer = ByteBuffer.allocate((int) bufferLength);
+        long valueLength = ExtAttr.INSTANCE.extattr_list_file(path, ExtAttr.EXTATTR_NAMESPACE_USER, buffer, new size_t(bufferLength)).longValue();
+
+        if (valueLength < 0) {
+            throw new IOException("errno: " + Native.getLastError());
+        }
+
+        return decodeStringList(buffer);
+    }
+
+    public static ByteBuffer get(String path, String name) throws IOException {
+        // get required buffer size
+        long bufferLength = ExtAttr.INSTANCE.extattr_get_file(path, ExtAttr.EXTATTR_NAMESPACE_USER, name, null, new size_t(0)).longValue();
+
+        if (bufferLength < 0) {
+            throw new IOException("errno: " + Native.getLastError());
+        }
+
+        if (bufferLength == 0) {
+            return ByteBuffer.allocate(0);
+        }
+
+        ByteBuffer buffer = ByteBuffer.allocate((int) bufferLength);
+        long valueLength = ExtAttr.INSTANCE.extattr_get_file(path, ExtAttr.EXTATTR_NAMESPACE_USER, name, buffer, new size_t(bufferLength)).longValue();
+
+        if (valueLength < 0) {
+            throw new IOException("errno: " + Native.getLastError());
+        }
+
+        return buffer;
+    }
+
+    public static void set(String path, String name, ByteBuffer value) throws IOException {
+        long r = ExtAttr.INSTANCE.extattr_set_file(path, ExtAttr.EXTATTR_NAMESPACE_USER, name, value, new size_t(value.remaining())).longValue();
+        if (r < 0) {
+            throw new IOException("errno: " + Native.getLastError());
+        }
+    }
+
+    public static void delete(String path, String name) throws IOException {
+        int r = ExtAttr.INSTANCE.extattr_delete_file(path, ExtAttr.EXTATTR_NAMESPACE_USER, name);
+        if (r < 0) {
+            throw new IOException("errno: " + Native.getLastError());
+        }
+    }
+
+    private static List<String> decodeStringList(ByteBuffer buffer) {
+        List<String> list = new ArrayList<String>();
+
+        while (buffer.hasRemaining()) {
+            int length = buffer.get() & 0xFF;
+            byte[] value = new byte[length];
+            buffer.get(value);
+
+            try {
+                list.add(new String(value, "UTF-8"));
+            } catch (UnsupportedEncodingException e) {
+                throw new RuntimeException(e);
+            }
+        }
+
+        return list;
+    }
+
+}