Add mapping for EnumProcesses to Psapi

CHANGES.md

@@ -19,6 +19,7 @@ Features
 * [#1200](https://github.com/java-native-access/jna/pull/1200): Add mappings for `libudev` to `c.s.j.p.linux.Udev` - [@dbwiddis](https://github.com/dbwiddis).
 * [#1202](https://github.com/java-native-access/jna/pull/1202): Add mappings supporting shared memory including `c.s.j.p.unix.LibCAPI` types `size_t` and `ssize_t`, `c.s.j.p.linux.LibC` methods `munmap()`, `msync()`, and `close()`, `c.s.j.p.unix.LibCUtil` mapping `mmap()` and `ftruncate()`, and `c.s.j.p.linux.LibRT` methods `shm_open()` and `shm_unlink()` - [@dbwiddis](https://github.com/dbwiddis).
 * [#1209](https://github.com/java-native-access/jna/pull/1209): Add mappings for `Thread32First` and `Thread32Next` to `c.s.j.p.win32.Kernel32` - [@dbwiddis](https://github.com/dbwiddis).
+* [#1214](https://github.com/java-native-access/jna/pull/1214): Add mapping for EnumProcesses to `c.s.j.p.win32.Psapi` - [@T-Svensson](https://github.com/T-Svensson/).
 
 Bug Fixes
 ---------

contrib/platform/src/com/sun/jna/platform/win32/Psapi.java

@@ -266,6 +266,46 @@ public interface Psapi extends StdCallLibrary {
      */
     boolean GetPerformanceInfo(PERFORMANCE_INFORMATION pPerformanceInformation, int cb);
 
+    /**
+     * Retrieves the process identifier for each process object in the system.
+     * <br>
+     * It is a good idea to use a large array, because it is hard to predict
+     * how many processes there will be at the time you call EnumProcesses.
+     * <br>
+     * To determine how many processes were enumerated, divide the
+     * pBytesReturned value by sizeof(DWORD). There is no indication given
+     * when the buffer is too small to store all process identifiers.
+     * Therefore, if pBytesReturned equals cb, consider retrying the call
+     * with a larger array.
+     * <br>
+     * To obtain process handles for the processes whose identifiers you
+     * have just obtained, call the OpenProcess function.
+     * <br>
+     * Starting with Windows 7 and Windows Server 2008 R2, Psapi.h
+     * establishes version numbers for the PSAPI functions. The PSAPI
+     * version number affects the name used to call the function and the
+     * library that a program must load.
+     * <br>
+     * If PSAPI_VERSION is 2 or greater, this function is defined as
+     * K32EnumProcesses in Psapi.h and exported in Kernel32.lib and
+     * Kernel32.dll. If PSAPI_VERSION is 1, this function is defined as
+     * EnumProcesses in Psapi.h and exported in Psapi.lib and Psapi.dll as a
+     * wrapper that calls K32EnumProcesses.
+     *
+     * @param lpidProcess
+     *            A pointer to an array that receives the list of process
+     *            identifiers
+     * @param cb
+     *            The size of the pProcessIds array, in bytes.
+     * @param lpcbNeeded
+     *            The number of bytes returned in the pProcessIds array.
+     * @return If the function succeeds, the return value is nonzero. If the
+     *         function fails, the return value is zero. To get extended
+     *         error information, call GetLastError.
+     * @see <a href="https://docs.microsoft.com/en-us/windows/win32/api/psapi/nf-psapi-enumprocesses">MSDN</a>
+     */
+    boolean EnumProcesses(int[] lpidProcess, int cb, IntByReference lpcbNeeded);
+
     @FieldOrder({"lpBaseOfDll", "SizeOfImage", "EntryPoint"})
     class MODULEINFO extends Structure {
         public Pointer EntryPoint;

contrib/platform/src/com/sun/jna/platform/win32/PsapiUtil.java

@@ -0,0 +1,58 @@
+/* Copyright (c) 2020 Torbjörn Svensson, 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.win32;
+
+import com.sun.jna.Native;
+import com.sun.jna.platform.win32.WinDef.DWORD;
+import com.sun.jna.ptr.IntByReference;
+
+/**
+ * Psapi utility API.
+ *
+ * @author Torbjörn Svensson, azoff[at]svenskalinuxforeninen.se
+ */
+public abstract class PsapiUtil {
+
+    /**
+     * Retrieves the process identifier for each process object in the system.
+     *
+     * @return Array of pids
+     */
+    public static int[] enumProcesses() {
+        int size = 0;
+        int[] lpidProcess = null;
+        IntByReference lpcbNeeded = new IntByReference();
+        do {
+            size = size + 1024;
+            lpidProcess = new int[size];
+            if (!Psapi.INSTANCE.EnumProcesses(lpidProcess, size * DWORD.SIZE, lpcbNeeded)) {
+                throw new Win32Exception(Native.getLastError());
+            }
+        } while (size == lpcbNeeded.getValue() / DWORD.SIZE);
+
+        int[] result = new int[lpcbNeeded.getValue() / DWORD.SIZE];
+        System.arraycopy(lpidProcess, 0, result, 0, result.length);
+        return result;
+    }
+}

contrib/platform/test/com/sun/jna/platform/win32/PsapiTest.java

@@ -248,4 +248,31 @@ public void testGetPerformanceInfo() {
         assertTrue(Psapi.INSTANCE.GetPerformanceInfo(perfInfo, perfInfo.size()));
         assertTrue(perfInfo.ProcessCount.intValue() > 0);
     }
+
+    @Test
+    public void EnumProcesses() {
+        int size = 0;
+        int[] lpidProcess = null;
+        IntByReference lpcbNeeded = new IntByReference();
+        do {
+            size = size + 1024;
+            lpidProcess = new int[size];
+            if (!Psapi.INSTANCE.EnumProcesses(lpidProcess, size * DWORD.SIZE, lpcbNeeded)) {
+                throw new Win32Exception(Native.getLastError());
+            }
+        } while (size == lpcbNeeded.getValue());
+
+        assertTrue("Size of pid list in bytes should be a multiple of " + DWORD.SIZE, lpcbNeeded.getValue() % DWORD.SIZE == 0);
+        assertTrue("List should contain atleast one pid", lpcbNeeded.getValue() > DWORD.SIZE);
+
+        int myPid = Kernel32.INSTANCE.GetCurrentProcessId();
+        boolean foundMyPid = false;
+        for (int i = 0; i < lpcbNeeded.getValue() / DWORD.SIZE; i++) {
+            if (lpidProcess[i] == myPid) {
+                foundMyPid = true;
+                break;
+            }
+        }
+        assertTrue("List should contain my pid", foundMyPid);
+    }
 }

contrib/platform/test/com/sun/jna/platform/win32/PsapiUtilTest.java

@@ -0,0 +1,52 @@
+/* Copyright (c) 2020 Torbjörn Svensson, 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.win32;
+
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+/**
+ * Applies API tests on {@link PsapiUtil}.
+ *
+ * @author Torbjörn Svensson, azoff[at]svenskalinuxforeninen.se
+ */
+public class PsapiUtilTest {
+    @Test
+    public void enumProcesses() {
+        int[] pids = PsapiUtil.enumProcesses();
+
+        assertTrue("List should contain atleast one pid", pids.length > 0);
+
+        int myPid = Kernel32.INSTANCE.GetCurrentProcessId();
+        boolean foundMyPid = false;
+        for (int i = 0; i < pids.length; i++) {
+            if (pids[i] == myPid) {
+                foundMyPid = true;
+                break;
+            }
+        }
+        assertTrue("List should contain my pid", foundMyPid);
+    }
+}