Added GetEnvironmentStrings to 'com.sun.jna.platform.win32.Kernel32' - [

@lgoldstein](https://github.com/lgoldstein).

CHANGES.md

@@ -44,6 +44,7 @@ Features
 * [#428](https://github.com/twall/jna/pull/428): Added Wincon.h related functions and definitions to `com.sun.jna.platform.win32.Kernel32` - [@lgoldstein](https://github.com/lgoldstein).
 * [#431](https://github.com/twall/jna/pull/431): Added named pipe API support to `com.sun.jna.platform.win32.Kernel32` - [@lgoldstein](https://github.com/lgoldstein).
 * [#432](https://github.com/twall/jna/pull/432): Added SetLocalTime definition to 'com.sun.jna.platform.win32.Kernel32' - [@lgoldstein](https://github.com/lgoldstein).
+* [#434](https://github.com/twall/jna/pull/434): Added GetEnvironmentStrings to 'com.sun.jna.platform.win32.Kernel32'  - [@lgoldstein](https://github.com/lgoldstein).
 
 Bug Fixes
 ---------

contrib/platform/src/com/sun/jna/platform/win32/Advapi32Util.java

@@ -1758,13 +1758,14 @@ public EnumKey(HKEY hKey, int dwIndex) {
 	 * @return A environment block
 	 */
 	public static String getEnvironmentBlock(Map<String, String> environment) {
-		StringBuilder out = new StringBuilder();
+		StringBuilder out = new StringBuilder(environment.size() * 32 /* some guess about average name=value length*/);
 		for (Entry<String, String> entry : environment.entrySet()) {
-			if (entry.getValue() != null) {
-				out.append(entry.getKey() + "=" + entry.getValue() + "\0");
+		    String    key=entry.getKey(), value=entry.getValue();
+			if (value != null) {
+				out.append(key).append("=").append(value).append('\0');
 			}
 		}
-		return out.toString() + "\0";
+		return out.append('\0').toString();
 	}
 
 	/**

contrib/platform/src/com/sun/jna/platform/win32/Kernel32.java

@@ -2210,6 +2210,34 @@ boolean GetDiskFreeSpaceEx(String lpDirectoryName,
      */
     int GetEnvironmentVariable(String lpName, char[] lpBuffer, int nSize);
 
+    /**
+     * <P>Retrieves the environment variables for the current process. The
+     * block of variables format is as follows:</P></BR>
+     * <code>
+     *      Var1=Value1\0
+     *      Var2=Value2\0
+     *      Var3=Value3\0
+     *      ...
+     *      VarN=ValueN\0\0
+     * </code>
+     * @return If the function succeeds, the return value is a {@link Pointer}.
+     * to the environment block of the current process. If fails, then
+     * {@code null} is returned. When the data is no longer needed the memory
+     * block must be released using {@link #FreeEnvironmentStrings(Pointer)}
+     * @see <A HREF="https://msdn.microsoft.com/en-us/library/windows/desktop/ms683187(v=vs.85).aspx">GetEnvironmentStrings</A> documentation
+     */
+    Pointer GetEnvironmentStrings();
+
+    /**
+     * @param lpszEnvironmentBlock A pointer to a block of environment strings
+     * obtained by calling the {@link #GetEnvironmentStrings()} function
+     * @return {@code true} if successful, {@code false} otherwise. 
+     * To get extended error information, call {@link #GetLastError()}. 
+     * @see <A HREF="https://msdn.microsoft.com/en-us/library/windows/desktop/ms683151(v=vs.85).aspx">FreeEnvironmentStrings</A>
+     * documentation
+     */
+    boolean FreeEnvironmentStrings(Pointer lpszEnvironmentBlock);
+
     /**
      * Returns the locale identifier for the system locale.
      * 

contrib/platform/src/com/sun/jna/platform/win32/Kernel32Util.java

@@ -14,12 +14,16 @@
 
 import java.io.File;
 import java.io.FileNotFoundException;
+import java.nio.ByteOrder;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
 
 import com.sun.jna.LastErrorException;
 import com.sun.jna.Memory;
 import com.sun.jna.Native;
+import com.sun.jna.Pointer;
 import com.sun.jna.platform.win32.WinNT.HANDLE;
 import com.sun.jna.platform.win32.WinNT.HANDLEByReference;
 import com.sun.jna.platform.win32.WinNT.HRESULT;
@@ -252,6 +256,176 @@ public static String getEnvironmentVariable(String name) {
         return Native.toString(buffer);
     }
 
+    /**
+     * Uses the {@link Kernel32#GetEnvironmentStrings()} to retrieve and
+     * parse the current process environment
+     * @return The current process environment as a {@link Map}.
+     * @throws LastErrorException if failed to get or free the environment
+     * data block
+     * @see #getEnvironmentVariables(Pointer, long)
+     */
+    public static Map<String,String> getEnvironmentVariables() {
+        Pointer lpszEnvironmentBlock=Kernel32.INSTANCE.GetEnvironmentStrings();
+        if (lpszEnvironmentBlock == null) {
+            throw new LastErrorException(Kernel32.INSTANCE.GetLastError());
+        }
+
+        try {
+            return getEnvironmentVariables(lpszEnvironmentBlock, 0L);
+        } finally {
+            if (!Kernel32.INSTANCE.FreeEnvironmentStrings(lpszEnvironmentBlock)) {
+                throw new LastErrorException(Kernel32.INSTANCE.GetLastError());
+            }
+        }
+    }
+
+    /**
+     * @param lpszEnvironmentBlock The environment block as received from the
+     * <A HREF="https://msdn.microsoft.com/en-us/library/windows/desktop/ms683187(v=vs.85).aspx">GetEnvironmentStrings</A>
+     * function
+     * @param offset Offset within the block to parse the data
+     * @return A {@link Map} of the parsed <code>name=value</code> pairs.
+     * <B>Note:</B> if the environment block is {@code null} then {@code null}
+     * is returned instead of an empty map since we want to distinguish
+     * between the case that the data block is {@code null} and when there are
+     * no environment variables (as unlikely as it may be) 
+     */
+    public static Map<String,String> getEnvironmentVariables(Pointer lpszEnvironmentBlock, long offset) {
+        if (lpszEnvironmentBlock == null) {
+            return null;
+        }
+
+        Map<String,String>  vars=new TreeMap<String,String>();
+        boolean             asWideChars=isWideCharEnvironmentStringBlock(lpszEnvironmentBlock, offset);
+        long                stepFactor=asWideChars ? 2L : 1L;
+        for (long    curOffset=offset; ; ) {
+            String  nvp=readEnvironmentStringBlockEntry(lpszEnvironmentBlock, curOffset, asWideChars);
+            int     len=nvp.length();
+            if (len == 0) { // found the ending '\0'
+                break;
+            }
+
+            int pos=nvp.indexOf('=');
+            if (pos < 0) {
+                throw new IllegalArgumentException("Missing variable value separator in " + nvp);
+            }
+
+            String  name=nvp.substring(0, pos), value=nvp.substring(pos + 1);
+            vars.put(name, value);
+
+            curOffset += (len + 1 /* skip the ending '\0' */) * stepFactor;
+        }
+
+        return vars;
+    }
+
+    /**
+     * @param lpszEnvironmentBlock The environment block as received from the
+     * <A HREF="https://msdn.microsoft.com/en-us/library/windows/desktop/ms683187(v=vs.85).aspx">GetEnvironmentStrings</A>
+     * function
+     * @param offset Offset within the block to look for the entry
+     * @param asWideChars If {@code true} then the block contains {@code wchar_t}
+     * instead of &quot;plain old&quot; {@code char}s
+     * @return A {@link String} containing the <code>name=value</code> pair or
+     * empty if reached end of block
+     * @see #isWideCharEnvironmentStringBlock(Pointer)
+     * @see #findEnvironmentStringBlockEntryEnd(Pointer, long, boolean)
+     */
+    public static String readEnvironmentStringBlockEntry(Pointer lpszEnvironmentBlock, long offset, boolean asWideChars) {
+        long endOffset=findEnvironmentStringBlockEntryEnd(lpszEnvironmentBlock, offset, asWideChars);
+        int  dataLen=(int) (endOffset - offset);
+        if (dataLen == 0) {
+            return "";
+        }
+
+        int         charsLen=asWideChars ? (dataLen / 2) : dataLen;
+        char[]      chars=new char[charsLen];
+        long        curOffset=offset, stepSize=asWideChars ? 2L : 1L;
+        ByteOrder   byteOrder=ByteOrder.nativeOrder();
+        for (int index=0; index < chars.length; index++, curOffset += stepSize) {
+            byte b=lpszEnvironmentBlock.getByte(curOffset);
+            if (asWideChars) {
+                byte x=lpszEnvironmentBlock.getByte(curOffset + 1L);
+                if (ByteOrder.LITTLE_ENDIAN.equals(byteOrder)) {
+                    chars[index] = (char) (((x << Byte.SIZE) & 0xFF00) | (b & 0x00FF));
+                } else {    // unlikely, but handle it
+                    chars[index] = (char) (((b << Byte.SIZE) & 0xFF00) | (x & 0x00FF));
+                }
+            } else {
+                chars[index] = (char) (b & 0x00FF);
+            }
+        }
+
+        return new String(chars);
+    }
+
+    /**
+     * @param lpszEnvironmentBlock The environment block as received from the
+     * <A HREF="https://msdn.microsoft.com/en-us/library/windows/desktop/ms683187(v=vs.85).aspx">GetEnvironmentStrings</A>
+     * function
+     * @param offset Offset within the block to look for the entry
+     * @param asWideChars If {@code true} then the block contains {@code wchar_t}
+     * instead of &quot;plain old&quot; {@code char}s
+     * @return The offset of the <U>first</U> {@code '\0'} in the data block
+     * starting at the specified offset - can be the start offset itself if empty
+     * string.
+     * @see #isWideCharEnvironmentStringBlock(Pointer)
+     */
+    public static long findEnvironmentStringBlockEntryEnd(Pointer lpszEnvironmentBlock, long offset, boolean asWideChars) {
+        for (long curOffset=offset, stepSize=asWideChars ? 2L : 1L; ; curOffset += stepSize) {
+            byte b=lpszEnvironmentBlock.getByte(curOffset);
+            if (b == 0) {
+                return curOffset;
+            }
+        }
+    }
+
+    /**
+     * <P>Attempts to determine whether the data block uses {@code wchar_t}
+     * instead of &quot;plain old&quot; {@code char}s. It does that by reading
+     * 2 bytes from the specified offset - the character value and its charset
+     * indicator - and examining them as follows:</P></BR>
+     * <UL>
+     *      <LI>
+     *      If the charset indicator is non-zero then it is assumed to be
+     *      a &quot;plain old&quot; {@code char}s data block. <B>Note:</B>
+     *      the assumption is that the environment variable <U>name</U> (at
+     *      least) is ASCII.
+     *      </LI>
+     *      
+     *      <LI>
+     *      Otherwise (i.e., zero charset indicator), it is assumed to be
+     *      a {@code wchar_t} 
+     *      </LI>
+     * </UL>
+     * <B>Note:</B> the code takes into account the {@link ByteOrder} even though
+     * only {@link ByteOrder#LITTLE_ENDIAN} is the likely one
+     * @param lpszEnvironmentBlock The environment block as received from the
+     * <A HREF="https://msdn.microsoft.com/en-us/library/windows/desktop/ms683187(v=vs.85).aspx">GetEnvironmentStrings</A>
+     * function
+     * @return {@code true} if the block contains {@code wchar_t} instead of
+     * &quot;plain old&quot; {@code char}s
+     */
+    public static boolean isWideCharEnvironmentStringBlock(Pointer lpszEnvironmentBlock, long offset) {
+        byte        b0=lpszEnvironmentBlock.getByte(offset);
+        byte        b1=lpszEnvironmentBlock.getByte(offset + 1L);
+        ByteOrder   byteOrder=ByteOrder.nativeOrder();
+        if (ByteOrder.LITTLE_ENDIAN.equals(byteOrder)) {
+            return isWideCharEnvironmentStringBlock(b1);
+        } else {
+            return isWideCharEnvironmentStringBlock(b0);
+        }
+    }
+
+    private static boolean isWideCharEnvironmentStringBlock(byte charsetIndicator) {
+        // assume wchar_t for environment variables represents ASCII letters
+        if (charsetIndicator != 0) {
+            return false;
+        } else {
+            return true;
+        }
+    }
+
     /**
      * Retrieves an integer associated with a key in the specified section of an
      * initialization file.

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

@@ -0,0 +1,90 @@
+/* Copyright (c) 2007 Timothy Wall, All Rights Reserved
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ */
+package com.sun.jna.platform.win32;
+
+import java.nio.ByteOrder;
+import java.util.Map;
+import java.util.Random;
+import java.util.TreeMap;
+
+import org.junit.Test;
+
+import com.sun.jna.Native;
+import com.sun.jna.Pointer;
+
+/**
+ * @author lgoldstein
+ */
+public class EnvironmentVarsTest extends AbstractWin32TestSupport {
+    public EnvironmentVarsTest() {
+        super();
+    }
+
+    @Test
+    public void testKernelUtilGetEnvironmentStrings() {
+        assertCurrentEnvironmentVariableValues(Kernel32Util.getEnvironmentVariables());
+    }
+
+    @Test
+    public void testGetEnvironmentStringsFromPointer() {
+        Pointer lpszEnvironmentBlock=Kernel32.INSTANCE.GetEnvironmentStrings();
+        assertNotNull("No environment data block returned", lpszEnvironmentBlock);
+        try {
+            assertCurrentEnvironmentVariableValues(Kernel32Util.getEnvironmentVariables(lpszEnvironmentBlock, 0L));
+        } finally {
+            assertCallSucceeded("FreeEnvironmentStrings", Kernel32.INSTANCE.FreeEnvironmentStrings(lpszEnvironmentBlock));
+        }
+    }
+
+    private static void assertCurrentEnvironmentVariableValues(Map<String,String> vars) {
+        for (Map.Entry<String,String> entry : vars.entrySet()) {
+            String  name=entry.getKey(), expected=entry.getValue();
+            char[]  data=new char[expected.length() + 1];
+            int     size=Kernel32.INSTANCE.GetEnvironmentVariable(name, data, data.length);
+            assertEquals("Mismatched retrieved length for " + name, data.length - 1 /* w/o the '\0' */, size);
+
+            String  actual=Native.toString(data);
+            assertEquals("Mismatched retrieved value for " + name, expected, actual);
+        }
+    }
+
+    @Test
+    public void testKernelSetAndGetEnvironmentVariable() {
+        String  name=getCurrentTestName(), expected="42";
+        assertCallSucceeded("SetEnvironmentVariable", Kernel32.INSTANCE.SetEnvironmentVariable(name, expected));
+
+        try {
+            int size = Kernel32.INSTANCE.GetEnvironmentVariable(name, null, 0);
+            assertEquals("Mismatched required buffer size", expected.length() + 1, size);
+
+            char[] data = new char[size];
+            assertEquals("Mismatched retrieved variable data length", size - 1, Kernel32.INSTANCE.GetEnvironmentVariable(name, data, size));
+
+            String  actual=Native.toString(data);
+            assertEquals("Mismatched retrieved variable value", expected, actual);
+        } finally {
+            assertCallSucceeded("Clean up variable", Kernel32.INSTANCE.SetEnvironmentVariable(name, null));
+        }
+    }
+
+    @Test
+    public void testKernelUtilGetEnvironmentVariable() {
+        String  name=getCurrentTestName(), expected=Integer.toString(new Random().nextInt());
+        assertCallSucceeded("SetEnvironmentVariable", Kernel32.INSTANCE.SetEnvironmentVariable(name, expected));
+        try {
+            assertEquals("Mismatched retrieved value", expected, Kernel32Util.getEnvironmentVariable(name));
+        } finally {
+            assertCallSucceeded("Clean up variable", Kernel32.INSTANCE.SetEnvironmentVariable(name, null));
+        }
+    }
+}

contrib/platform/test/com/sun/jna/platform/win32/Kernel32Test.java

@@ -539,21 +539,6 @@ public void testCreateProcess() {
         assertTrue(processInformation.dwProcessId.longValue() > 0);
     }
 
-    public void testGetEnvironmentVariable() {
-    	assertTrue(Kernel32.INSTANCE.SetEnvironmentVariable("jna-getenvironment-test", "42"));
-    	int size = Kernel32.INSTANCE.GetEnvironmentVariable("jna-getenvironment-test", null, 0);
-    	assertTrue(size == 3);
-    	char[] data = new char[size];
-    	assertEquals(size - 1, Kernel32.INSTANCE.GetEnvironmentVariable("jna-getenvironment-test", data, size));
-    	assertEquals(size - 1, Native.toString(data).length());
-    }
-
-    public void testSetEnvironmentVariable() {
-        int value = new Random().nextInt();
-        Kernel32.INSTANCE.SetEnvironmentVariable("jna-setenvironment-test", Integer.toString(value));
-        assertEquals(Integer.toString(value), Kernel32Util.getEnvironmentVariable("jna-setenvironment-test"));
-    }
-
     public void testGetSetFileTime() throws IOException {
         File tmp = File.createTempFile("testGetSetFileTime", "jna");
         tmp.deleteOnExit();