Add Linux LibC with sysinfo

CHANGES.md

@@ -27,6 +27,7 @@ Features
 * [#984](https://github.com/java-native-access/jna/issues/984): Added `CM_Locate_DevNode`, `CM_Get_Parent`, `CM_Get_Child`, `CM_Get_Sibling`, `CM_Get_Device_ID`, and `CM_Get_Device_ID_Size` to `c.s.j.platform.win32.Cfgmgr32.java` and a `c.s.j.platform.win32.Cfgmgr32Util` class for `CM_Get_Device_ID` - [@dbwiddis](https://github.com/dbwiddis).
 * [#988](https://github.com/java-native-access/jna/issues/988): Added `PdhLookupPerfIndexByEnglishName` to `c.s.j.platform.win32.PdhUtil` - [@dbwiddis](https://github.com/dbwiddis).
 * [#992](https://github.com/java-native-access/jna/pull/992): Improve stability of windows tests and add appveyor configuration for windows CI builds - [@matthiasblaesing](https://github.com/matthiasblaesing).
+* [#997](https://github.com/java-native-access/jna/issues/997): Added `Sysinfo` structure and function to `c.s.j.platform.linux.LibC` - [@dbwiddis](https://github.com/dbwiddis).
 
 Bug Fixes
 ---------

contrib/platform/src/com/sun/jna/platform/linux/LibC.java

@@ -0,0 +1,76 @@
+/* Copyright (c) 2017 Daniel Widdis, 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.linux;
+
+import com.sun.jna.Library;
+import com.sun.jna.Native;
+import com.sun.jna.NativeLong;
+import com.sun.jna.Structure;
+import com.sun.jna.Structure.FieldOrder;
+import com.sun.jna.platform.unix.LibCAPI;
+
+/**
+ * <I>libc</I> API
+ * 
+ * @author Daniel Widdis
+ */
+public interface LibC extends LibCAPI, Library {
+    String NAME = "c";
+    LibC INSTANCE = Native.load(NAME, LibC.class);
+
+    @FieldOrder({ "uptime", "loads", "totalram", "freeram", "sharedram", "bufferram", "totalswap", "freeswap", "procs",
+            "totalhigh", "freehigh", "mem_unit", "_f" })
+    class Sysinfo extends Structure {
+        public NativeLong uptime; // Seconds since boot
+        // 1, 5, and 15 minute load averages
+        public NativeLong[] loads = new NativeLong[3];
+        public NativeLong totalram; // Total usable main memory size
+        public NativeLong freeram; // Available memory size
+        public NativeLong sharedram; // Amount of shared memory
+        public NativeLong bufferram; // Memory used by buffers
+        public NativeLong totalswap; // Total swap space size
+        public NativeLong freeswap; // swap space still available
+        public short procs; // Number of current processes
+        public NativeLong totalhigh; // Total high memory size
+        public NativeLong freehigh; // Available high memory size
+        public int mem_unit; // Memory unit size in bytes
+        // Padding is based on the size of NativeLong. When the size is 4 we
+        // need 8 bytes of padding. When this size is 8, zero padding is needed
+        // but we are not allowed to declare an array of size zero. It's safe to
+        // declare extra padding in the structure; these bytes simply will not
+        // be written on 64-bit systems.
+        public byte[] _f = new byte[8]; // padding to 64 bytes
+    }
+
+    /**
+     * sysinfo() provides a simple way of getting overall system statistics.
+     * This is more portable than reading /dev/kmem.
+     * 
+     * @param info
+     *            A Sysinfo structure which will be populated
+     * @return On success, zero is returned. On error, -1 is returned, and errno
+     *         is set appropriately.
+     */
+    int sysinfo(Sysinfo info);
+}

contrib/platform/src/com/sun/jna/platform/linux/package.html

@@ -0,0 +1,13 @@
+<html>
+<head>
+<!-- 
+  Copyright (c) 2017 Daniel Widdis
+-->
+</head>
+<body bgcolor="white">
+
+<!-- One sentence summary -->
+Provides common library mappings for Linux.
+
+</body>
+</html>

contrib/platform/test/com/sun/jna/platform/linux/LibCTest.java

@@ -0,0 +1,57 @@
+/* Copyright (c) 2017 Daniel Widdis, 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.linux;
+
+import org.junit.Test;
+
+import com.sun.jna.platform.linux.LibC;
+import com.sun.jna.platform.linux.LibC.Sysinfo;
+
+import junit.framework.TestCase;
+
+/**
+ * Exercise the {@link LibC} class.
+ *
+ * @author widdis@gmail.com
+ */
+public class LibCTest extends TestCase {
+
+    @Test
+    public void testSysinfo() {
+        Sysinfo info = new Sysinfo();
+        assertEquals(0, LibC.INSTANCE.sysinfo(info));
+
+        // Get loadavg for comparison (rounds to nearest hundredth)
+        double[] loadavg = new double[3];
+        LibC.INSTANCE.getloadavg(loadavg, 3);
+        // Sysinfo loadavg longs must be divided by 2^16
+        for (int i = 0; i < 3; i++) {
+            assertEquals(loadavg[i], info.loads[i].longValue() / (float) (1 << 16), 0.02);
+        }
+        assertTrue(info.uptime.longValue() > 0);
+        assertTrue(info.totalram.longValue() > 0);
+        assertTrue(info.freeram.longValue() <= info.totalram.longValue());
+        assertTrue(info.freeswap.longValue() <= info.totalswap.longValue());
+    }
+}