Add mapping for EnumProcesses to Psapi

Added utility method QueryFullProcessImageName that takes a PID.
Fixed QueryFullProcessImageName to properly handle paths longer than 260
characters that can happen on Win10 / paths with UNC.

Author: T-Svensson

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/Kernel32Util.java

@@ -854,6 +854,49 @@ public static final String extractVolumeGUID(String volumeGUIDPath) {
         return volumeGUIDPath.substring(VOLUME_GUID_PATH_PREFIX.length(), volumeGUIDPath.length() - VOLUME_GUID_PATH_SUFFIX.length());
     }
 
+    /**
+     *
+     * This function retrieves the full path of the executable file of a given process identifier.
+     *
+     * @param pid
+     *          Identifier for the running process
+     * @param dwFlags
+     *          0 - The name should use the Win32 path format.
+     *          1(WinNT.PROCESS_NAME_NATIVE) - The name should use the native system path format.
+     *
+     * @return the full path of the process's executable file of null if failed. To get extended error information,
+     *         call GetLastError.
+     */
+    public static final String QueryFullProcessImageName(int pid, int dwFlags) {
+        HANDLE hProcess = null;
+        Win32Exception we = null;
+
+        try {
+            hProcess = Kernel32.INSTANCE.OpenProcess(WinNT.PROCESS_QUERY_INFORMATION | WinNT.PROCESS_VM_READ, false, pid);
+            if (hProcess == null) {
+                throw new Win32Exception(Kernel32.INSTANCE.GetLastError());
+            }
+
+            return QueryFullProcessImageName(hProcess, dwFlags);
+        } catch (Win32Exception e) {
+            we = e;
+            throw we; // re-throw to invoke finally block
+        } finally {
+            try {
+                closeHandle(hProcess);
+            } catch (Win32Exception e) {
+                if (we == null) {
+                    we = e;
+                } else {
+                    we.addSuppressed(e);
+                }
+            }
+            if (we != null) {
+                throw we;
+            }
+        }
+    }
+
     /**
      *
      * This function retrieves the full path of the executable file of a given process.
@@ -868,10 +911,16 @@ public static final String extractVolumeGUID(String volumeGUIDPath) {
      *         call GetLastError.
      */
     public static final String QueryFullProcessImageName(HANDLE hProcess, int dwFlags) {
-        char[] path = new char[WinDef.MAX_PATH];
-        IntByReference lpdwSize = new IntByReference(path.length);
-        if (Kernel32.INSTANCE.QueryFullProcessImageName(hProcess, 0, path, lpdwSize))
-            return new String(path).substring(0, lpdwSize.getValue());
+        int size = 0;
+        IntByReference lpdwSize = new IntByReference();
+        do {
+            size = size + (size == 0 ? WinDef.MAX_PATH : 1024); // Start with MAX_PATH, then increment with 1024 each iteration
+            char[] lpExeName = new char[size];
+            lpdwSize.setValue(size);
+            if (Kernel32.INSTANCE.QueryFullProcessImageName(hProcess, dwFlags, lpExeName, lpdwSize)) {
+                return new String(lpExeName, 0, lpdwSize.getValue());
+            }
+        } while (Kernel32.INSTANCE.GetLastError() == Kernel32.ERROR_INSUFFICIENT_BUFFER);
         throw new Win32Exception(Kernel32.INSTANCE.GetLastError());
     }
 

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 +1,57 @@
+/* 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 java.util.Arrays;
+
+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(Kernel32.INSTANCE.GetLastError());
+            }
+        } while (size == lpcbNeeded.getValue() / DWORD.SIZE);
+
+        return Arrays.copyOf(lpidProcess, lpcbNeeded.getValue() / DWORD.SIZE);
+    }
+}

contrib/platform/test/com/sun/jna/platform/win32/Kernel32UtilTest.java

@@ -313,14 +313,28 @@ public final void testWritePrivateProfileSection() throws IOException {
     }
 
     public final void testQueryFullProcessImageName() {
-        HANDLE h = Kernel32.INSTANCE.OpenProcess(WinNT.PROCESS_QUERY_INFORMATION, false, Kernel32.INSTANCE.GetCurrentProcessId());
+        int pid = Kernel32.INSTANCE.GetCurrentProcessId();
+
+        HANDLE h = Kernel32.INSTANCE.OpenProcess(WinNT.PROCESS_QUERY_INFORMATION, false, pid);
         assertNotNull("Failed (" + Kernel32.INSTANCE.GetLastError() + ") to get process handle", h);
         try {
             String name = Kernel32Util.QueryFullProcessImageName(h, 0);
+            assertNotNull("Failed to query process image name, null path returned", name);
             assertTrue("Failed to query process image name, empty path returned", name.length() > 0);
         } finally {
             Kernel32Util.closeHandle(h);
         }
+
+        String name = Kernel32Util.QueryFullProcessImageName(pid, 0);
+        assertNotNull("Failed to query process image name, null path returned", name);
+        assertTrue("Failed to query process image name, empty path returned", name.length() > 0);
+
+        try {
+            Kernel32Util.QueryFullProcessImageName(0, 0); // the system process
+            fail("Should never reach here");
+        } catch (Win32Exception expected) {
+            assertEquals("Should get Invalid Parameter error", Kernel32.ERROR_INVALID_PARAMETER, expected.getErrorCode());
+        }
     }
 
     public void testGetResource() {

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

@@ -25,6 +25,7 @@
 
 import static org.junit.Assert.assertTrue;
 
+import java.util.Arrays;
 import java.util.LinkedList;
 import java.util.List;
 
@@ -248,4 +249,29 @@ public void testGetPerformanceInfo() {
         assertTrue(Psapi.INSTANCE.GetPerformanceInfo(perfInfo, perfInfo.size()));
         assertTrue(perfInfo.ProcessCount.intValue() > 0);
     }
+
+    @Test
+    public void testEnumProcesses() {
+        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(Kernel32.INSTANCE.GetLastError());
+            }
+        } while (size == lpcbNeeded.getValue() / DWORD.SIZE);
+        assertTrue("Size of pid list in bytes should be a multiple of " + DWORD.SIZE, lpcbNeeded.getValue() % DWORD.SIZE == 0);
+
+        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 +1,53 @@
+/* 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.assertNotNull;
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+/**
+ * Applies API tests on {@link PsapiUtil}.
+ *
+ * @author Torbjörn Svensson, azoff[at]svenskalinuxforeninen.se
+ */
+@SuppressWarnings("nls")
+public class PsapiUtilTest {
+    @Test
+    public void enumProcesses() {
+        int[] pids = PsapiUtil.enumProcesses();
+        assertNotNull("List should not be null", pids);
+
+        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);
+    }
+}