bug 357442: Added $CYGWIN_HOME to cygwin toolchain detection algorithm

8 files changed, 790 insertions, 383 deletions

diff --git a/build/org.eclipse.cdt.make.core/src/org/eclipse/cdt/make/internal/core/scannerconfig/util/CygpathTranslator.java b/build/org.eclipse.cdt.make.core/src/org/eclipse/cdt/make/internal/core/scannerconfig/util/CygpathTranslator.java
index 820df07aac7..3dca63cf0c0 100644
--- a/build/org.eclipse.cdt.make.core/src/org/eclipse/cdt/make/internal/core/scannerconfig/util/CygpathTranslator.java
+++ b/build/org.eclipse.cdt.make.core/src/org/eclipse/cdt/make/internal/core/scannerconfig/util/CygpathTranslator.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2004, 2011 IBM Corporation and others.
+ * Copyright (c) 2004, 2013 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -20,8 +20,14 @@ import java.util.List;
 
 import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.IBinaryParser;
+import org.eclipse.cdt.core.envvar.IEnvironmentVariable;
+import org.eclipse.cdt.core.envvar.IEnvironmentVariableManager;
 import org.eclipse.cdt.core.model.CoreModelUtil;
 import org.eclipse.cdt.core.settings.model.ICConfigExtensionReference;
+import org.eclipse.cdt.core.settings.model.ICConfigurationDescription;
+import org.eclipse.cdt.core.settings.model.ICProjectDescription;
+import org.eclipse.cdt.internal.core.Cygwin;
+import org.eclipse.cdt.make.core.MakeCorePlugin;
 import org.eclipse.cdt.utils.CygPath;
 import org.eclipse.cdt.utils.ICygwinToolsFactroy;
 import org.eclipse.core.resources.IProject;
@@ -32,125 +38,135 @@ import org.eclipse.core.runtime.Platform;
 
 /**
  * Use binary parser's 'cygpath' command to translate cygpaths to absolute paths.
+ * Note that this class does not support build configurations.
  * 
  * @author vhirsl
  */
 public class CygpathTranslator {
-	/** Default Cygwin root dir */
-	private static final String DEFAULT_CYGWIN_ROOT= "C:\\cygwin"; //$NON-NLS-1$
-	//    private static final String CYGPATH_ERROR_MESSAGE = "CygpathTranslator.NotAvailableErrorMessage"; //$NON-NLS-1$
-    private CygPath cygPath = null;
-    private boolean isAvailable = false;
-    
-    public CygpathTranslator(IProject project) {
-        try {
-            ICConfigExtensionReference[] parserRef = CCorePlugin.getDefault().getDefaultBinaryParserExtensions(project);
-            for (int i = 0; i < parserRef.length; i++) {
-                try {
-                    IBinaryParser parser = CoreModelUtil.getBinaryParser(parserRef[i]);
-                    ICygwinToolsFactroy cygwinToolFactory = (ICygwinToolsFactroy) parser.getAdapter(ICygwinToolsFactroy.class);
-                    if (cygwinToolFactory != null) {
-                        cygPath = cygwinToolFactory.getCygPath();
-                        if (cygPath != null) {
-                            isAvailable = true;
-                            break;
-                        }
-                    }
-                } catch (ClassCastException e) {
-                }
-            }
-            // No CygPath specified in BinaryParser page or not supported.
-            // Hoping that cygpath is on the path.
-            if (cygPath == null && Platform.getOS().equals(Platform.OS_WIN32)) {
-            	if (new File(DEFAULT_CYGWIN_ROOT).exists()) {
-                    cygPath = new CygPath(DEFAULT_CYGWIN_ROOT + "\\bin\\cygpath.exe"); //$NON-NLS-1$
-            	} else {
-            		cygPath = new CygPath("cygpath"); //$NON-NLS-1$
-            	}
-                isAvailable = cygPath.getFileName("test").equals("test"); //$NON-NLS-1$ //$NON-NLS-2$
-            }
-        }
-        catch (CoreException e) {
-        }
-        catch (IOException e) {
-            isAvailable = false;
-            // Removing markers. if cygpath isn't in your path then you aren't using cygwin.
-            // Then why are we calling this....
-//            scMarkerGenerator.addMarker(project, -1,
-//                    MakeMessages.getString(CYGPATH_ERROR_MESSAGE),
-//                    IMarkerGenerator.SEVERITY_WARNING, null);
-        }
-    }
-    
-    public static List<String> translateIncludePaths(IProject project, List<String> sumIncludes) {
-    	// first check if cygpath translation is needed at all
-    	boolean translationNeeded = false;
-    	if (Platform.getOS().equals(Platform.OS_WIN32)) {
-	    	for (Iterator<String> i = sumIncludes.iterator(); i.hasNext(); ) {
+	private static final String ENV_PATH = "PATH"; //$NON-NLS-1$
+
+	private CygPath cygPath = null;
+
+	public CygpathTranslator(IProject project) {
+		try {
+			ICConfigExtensionReference[] parserRef = CCorePlugin.getDefault().getDefaultBinaryParserExtensions(project);
+			for (int i = 0; i < parserRef.length; i++) {
+				try {
+					IBinaryParser parser = CoreModelUtil.getBinaryParser(parserRef[i]);
+					ICygwinToolsFactroy cygwinToolFactory = (ICygwinToolsFactroy) parser.getAdapter(ICygwinToolsFactroy.class);
+					if (cygwinToolFactory != null) {
+						cygPath = cygwinToolFactory.getCygPath();
+					}
+				} catch (ClassCastException e) {
+				}
+			}
+		}
+		catch (CoreException e) {
+		}
+	}
+
+	public static List<String> translateIncludePaths(IProject project, List<String> sumIncludes) {
+		// first check if cygpath translation is needed at all
+		boolean translationNeeded = false;
+		if (Platform.getOS().equals(Platform.OS_WIN32)) {
+			for (Iterator<String> i = sumIncludes.iterator(); i.hasNext(); ) {
 				String include = i.next();
 				if (include.startsWith("/")) { //$NON-NLS-1$
 					translationNeeded = true;
 					break;
 				}
 			}
-    	}
-    	if (!translationNeeded) {
-    		return sumIncludes;
-    	}
-    	
-        CygpathTranslator cygpath = new CygpathTranslator(project);
-        
-        List<String> translatedIncludePaths = new ArrayList<String>();
-        for (Iterator<String> i = sumIncludes.iterator(); i.hasNext(); ) {
-            String includePath = i.next();
-            IPath realPath = new Path(includePath);
-            // only allow native pathes if they have a device prefix
-            // to avoid matches on the current drive, e.g. /usr/bin = C:\\usr\\bin
-            if (realPath.getDevice() != null && realPath.toFile().exists()) {
-                translatedIncludePaths.add(includePath);
-            }
-            else {
-                String translatedPath = includePath;
-                if (cygpath.isAvailable) {
-                    try {
-                        translatedPath = cygpath.cygPath.getFileName(includePath);
-                    }
-                    catch (IOException e) {
-                        TraceUtil.outputError("CygpathTranslator unable to translate path: ", includePath); //$NON-NLS-1$
-                    }
-                } else if (realPath.segmentCount() >= 2) {
-                	// try default conversions
-                	//     /cygdrive/x/ --> X:\
-                	if ("cygdrive".equals(realPath.segment(0))) { //$NON-NLS-1$
-                		String drive= realPath.segment(1);
-                		if (drive.length() == 1) {
-                			translatedPath= realPath.removeFirstSegments(2).makeAbsolute().setDevice(drive.toUpperCase() + ':').toOSString();
-                		}
-                	}
-                }
-                if (!translatedPath.equals(includePath)) {
-                    // Check if the translated path exists
-                    if (new File(translatedPath).exists()) {
-                        translatedIncludePaths.add(translatedPath);
-                    }
-                    else if (cygpath.isAvailable) {
-                        // TODO VMIR for now add even if it does not exist
-                        translatedIncludePaths.add(translatedPath);
-                    }
-                    else {
-                        translatedIncludePaths.add(includePath);
-                    }
-                }
-                else {
-                    // TODO VMIR for now add even if it does not exist
-                    translatedIncludePaths.add(translatedPath);
-                }
-            }
-        }
-        if (cygpath.cygPath != null) {
-        	cygpath.cygPath.dispose();
-        }
-        return translatedIncludePaths;
-    }
+		}
+		if (!translationNeeded) {
+			return sumIncludes;
+		}
+
+		CygpathTranslator cygpath = new CygpathTranslator(project);
+		boolean useCygPathExtension = cygpath.cygPath != null;
+		boolean useCygwinFromPath = !useCygPathExtension;
+
+		String envPath = null;
+		if (useCygwinFromPath) {
+			IEnvironmentVariableManager mngr = CCorePlugin.getDefault().getBuildEnvironmentManager();
+			ICProjectDescription prjDes = CCorePlugin.getDefault().getProjectDescription(project, false);
+			if (prjDes != null) {
+				// we don't know for sure which configuration needs to be used here, so betting on "DefaultSettingConfiguration"
+				// considering that scanner discovery uses "DefaultSettingConfiguration" rather than "Active" configuration,
+				// see org.eclipse.cdt.build.core.scannerconfig.ScannerConfigBuilder.build(CfgInfoContext context, ...)
+				ICConfigurationDescription cfgDes = prjDes.getDefaultSettingConfiguration();
+				IEnvironmentVariable envVar = mngr.getVariable(ENV_PATH, cfgDes, true);
+				if (envVar != null) {
+					envPath = envVar.getValue();
+				}
+			}
+			if (envPath == null) {
+				IEnvironmentVariable envVar = mngr.getVariable(ENV_PATH, null, true);
+				if (envVar != null) {
+					envPath = envVar.getValue();
+				}
+			}
+
+			useCygwinFromPath = Cygwin.isAvailable(envPath);
+		}
+
+		List<String> translatedIncludePaths = new ArrayList<String>();
+		for (Iterator<String> i = sumIncludes.iterator(); i.hasNext(); ) {
+			String includePath = i.next();
+			IPath realPath = new Path(includePath);
+			// only allow native pathes if they have a device prefix
+			// to avoid matches on the current drive, e.g. /usr/bin = C:\\usr\\bin
+			if (realPath.getDevice() != null && realPath.toFile().exists()) {
+				translatedIncludePaths.add(includePath);
+			}
+			else {
+				String translatedPath = includePath;
+
+				if (useCygPathExtension) {
+					try {
+						translatedPath = cygpath.cygPath.getFileName(includePath);
+					}
+					catch (IOException e) {
+						TraceUtil.outputError("CygpathTranslator unable to translate path: ", includePath); //$NON-NLS-1$
+					}
+				} else if (useCygwinFromPath) {
+					try {
+						translatedPath = Cygwin.cygwinToWindowsPath(includePath, envPath);
+					} catch (Exception e) {
+						MakeCorePlugin.log(e);
+					}
+				} else if (realPath.segmentCount() >= 2) {
+					// try default conversions
+					//     /cygdrive/x/ --> X:\
+					if ("cygdrive".equals(realPath.segment(0))) { //$NON-NLS-1$
+						String drive= realPath.segment(1);
+						if (drive.length() == 1) {
+							translatedPath= realPath.removeFirstSegments(2).makeAbsolute().setDevice(drive.toUpperCase() + ':').toOSString();
+						}
+					}
+				}
+				if (!translatedPath.equals(includePath)) {
+					// Check if the translated path exists
+					if (new File(translatedPath).exists()) {
+						translatedIncludePaths.add(translatedPath);
+					}
+					else if (useCygPathExtension || useCygwinFromPath) {
+						// TODO VMIR for now add even if it does not exist
+						translatedIncludePaths.add(translatedPath);
+					}
+					else {
+						translatedIncludePaths.add(includePath);
+					}
+				}
+				else {
+					// TODO VMIR for now add even if it does not exist
+					translatedIncludePaths.add(translatedPath);
+				}
+			}
+		}
+		if (useCygPathExtension) {
+			cygpath.cygPath.dispose();
+		}
+		return translatedIncludePaths;
+	}
 
 }
diff --git a/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/envvar/EnvironmentVariableManagerToolChain.java b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/envvar/EnvironmentVariableManagerToolChain.java
new file mode 100644
index 00000000000..5072fc95c50
--- /dev/null
+++ b/build/org.eclipse.cdt.managedbuilder.core/src/org/eclipse/cdt/managedbuilder/internal/envvar/EnvironmentVariableManagerToolChain.java
@@ -0,0 +1,220 @@
+/*******************************************************************************
+ * Copyright (c) 2012, 2012 Andrew Gvozdev and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ * Andrew Gvozdev - Initial API and implementation
+ *******************************************************************************/
+package org.eclipse.cdt.managedbuilder.internal.envvar;
+
+import org.eclipse.cdt.core.cdtvariables.ICdtVariable;
+import org.eclipse.cdt.core.envvar.IEnvironmentVariable;
+import org.eclipse.cdt.core.settings.model.ICConfigurationDescription;
+import org.eclipse.cdt.internal.core.cdtvariables.DefaultVariableContextInfo;
+import org.eclipse.cdt.internal.core.cdtvariables.EnvironmentVariableSupplier;
+import org.eclipse.cdt.internal.core.cdtvariables.ICoreVariableContextInfo;
+import org.eclipse.cdt.internal.core.envvar.DefaultEnvironmentContextInfo;
+import org.eclipse.cdt.internal.core.envvar.EnvVarDescriptor;
+import org.eclipse.cdt.internal.core.envvar.EnvironmentVariableManager;
+import org.eclipse.cdt.internal.core.envvar.ICoreEnvironmentVariableSupplier;
+import org.eclipse.cdt.internal.core.envvar.IEnvironmentContextInfo;
+import org.eclipse.cdt.managedbuilder.core.IConfiguration;
+import org.eclipse.cdt.managedbuilder.core.IToolChain;
+import org.eclipse.cdt.managedbuilder.core.ManagedBuildManager;
+import org.eclipse.cdt.managedbuilder.envvar.IConfigurationEnvironmentVariableSupplier;
+import org.eclipse.cdt.managedbuilder.envvar.IEnvironmentVariableProvider;
+import org.eclipse.cdt.utils.cdtvariables.ICdtVariableSupplier;
+import org.eclipse.cdt.utils.cdtvariables.IVariableContextInfo;
+
+
+/**
+ * Helper class to resolve environment variables directly from toolchain. The intention is
+ * to use that in New Project Wizard scenarios when no configuration is available yet.
+ */
+public class EnvironmentVariableManagerToolChain extends EnvironmentVariableManager {
+	private static EnvironmentVariableManagerToolChain fInstance = null;
+
+	/**
+	 * Basically, converter from IEnvironmentVariable to ICdtVariable (build macros) which
+	 * is used by EnvironmentVariableManager implementation to resolve variables/macros.
+	 */
+	private final class CoreVariableContextInfoToolChain implements ICoreVariableContextInfo {
+		public final static int CONTEXT_TOOLCHAIN = 1009; // arbitrary value different from ICoreVariableContextInfo.CONTEXT_XXX
+		
+		private final IToolChain toolChain;
+		private final IConfigurationEnvironmentVariableSupplier mbsSupplier;
+
+		private CoreVariableContextInfoToolChain(IToolChain toolChain) {
+			this.toolChain = toolChain;
+			this.mbsSupplier = toolChain.getEnvironmentVariableSupplier();
+		}
+
+		@Override
+		public ICdtVariableSupplier[] getSuppliers() {
+			ICdtVariableSupplier sup = new ICdtVariableSupplier() {
+				@Override
+				public ICdtVariable getVariable(String macroName, IVariableContextInfo context) {
+					IEnvironmentVariable var = mbsSupplier.getVariable(macroName, null, ManagedBuildManager.getEnvironmentVariableProvider());
+					return EnvironmentVariableSupplier.getInstance().createBuildMacro(var);
+				}
+				@Override
+				public ICdtVariable[] getVariables(IVariableContextInfo context) {
+					IEnvironmentVariable[] vars = mbsSupplier.getVariables(null, ManagedBuildManager.getEnvironmentVariableProvider());
+					if (vars != null) {
+						ICdtVariable[] cdtVars = new ICdtVariable[vars.length];
+						for (int i = 0; i < vars.length; i++) {
+							cdtVars[i] = EnvironmentVariableSupplier.getInstance().createBuildMacro(vars[i]);
+						}
+					}
+					return null;
+				}
+				
+			};
+			return new ICdtVariableSupplier[] { sup };
+		}
+
+		@Override
+		public IVariableContextInfo getNext() {
+			return new DefaultVariableContextInfo(ICoreVariableContextInfo.CONTEXT_WORKSPACE, null);
+		}
+
+		@Override
+		public int getContextType() {
+			return CONTEXT_TOOLCHAIN;
+		}
+
+		@Override
+		public Object getContextData() {
+			return toolChain;
+		}
+	}
+
+	private final class EnvironmentContextInfoToolChain implements IEnvironmentContextInfo {
+		private final IToolChain toolChain;
+
+		private EnvironmentContextInfoToolChain(IToolChain toolChain) {
+			this.toolChain = toolChain;
+		}
+
+		@Override
+		public IEnvironmentContextInfo getNext() {
+			return new DefaultEnvironmentContextInfo(null);
+		}
+
+		@Override
+		public ICoreEnvironmentVariableSupplier[] getSuppliers() {
+			final IConfigurationEnvironmentVariableSupplier cevSupplier = toolChain.getEnvironmentVariableSupplier();
+			
+			ICoreEnvironmentVariableSupplier toolchainSupplier = new ICoreEnvironmentVariableSupplier() {
+				@Override
+				public IEnvironmentVariable getVariable(String name, Object context) {
+					IEnvironmentVariableProvider provider = ManagedBuildManager.getEnvironmentVariableProvider();
+					return cevSupplier.getVariable(name, null, provider);
+				}
+				@Override
+				public IEnvironmentVariable[] getVariables(Object context) {
+					return cevSupplier.getVariables(null, ManagedBuildManager.getEnvironmentVariableProvider());
+				}
+				@Override
+				public boolean appendEnvironment(Object context) {
+					// Arbitrary value, it did not appear being used in tested scenarios
+					return false;
+				}
+			};
+			return new ICoreEnvironmentVariableSupplier[] { EnvironmentVariableManagerToolChain.fUserSupplier, toolchainSupplier };
+		}
+
+		@Override
+		public Object getContext() {
+			return toolChain;
+		}
+	}
+
+	public static EnvironmentVariableManagerToolChain getDefault() {
+		if (fInstance == null)
+			fInstance = new EnvironmentVariableManagerToolChain();
+		return fInstance;
+	}
+
+	@Override
+	public IEnvironmentContextInfo getContextInfo(Object level) {
+		if (level instanceof IToolChain) {
+			return new EnvironmentContextInfoToolChain((IToolChain) level);
+		}
+
+		return super.getContextInfo(level);
+	}
+
+	@Override
+	protected int getMacroContextTypeFromContext(Object context) {
+		if (context instanceof IToolChain) {
+			return CoreVariableContextInfoToolChain.CONTEXT_TOOLCHAIN;
+		}
+		
+		return super.getMacroContextTypeFromContext(context);
+	}
+
+	@Override
+	public ICoreVariableContextInfo getMacroContextInfoForContext(Object context) {
+		if (context instanceof IToolChain) {
+			return new CoreVariableContextInfoToolChain((IToolChain) context);
+		}
+
+		return super.getMacroContextInfoForContext(context);
+	}
+
+	/**
+	 * Get environment variable value from toolchain definition.
+	 *
+	 * @param name - name of the variable.
+	 * @param toolChain - toolchain.
+	 * @param resolveMacros - {@code true} to expand macros, {@code false} otherwise.
+	 *
+	 * @return value of the variable.
+	 */
+	public IEnvironmentVariable getVariable(String name, IToolChain toolChain, boolean resolveMacros) {
+		if (name == null || name.isEmpty())
+			return null;
+
+		IEnvironmentContextInfo info = getContextInfo(toolChain);
+		EnvVarDescriptor var = EnvironmentVariableManagerToolChain.getVariable(name,info,true);
+
+		if (var != null && var.getOperation() != IEnvironmentVariable.ENVVAR_REMOVE) {
+			return resolveMacros ? calculateResolvedVariable(var,info) : var;
+		}
+		return null;
+	}
+
+	/**
+	 * Get environment variable value resolved in context of configuration.
+	 * If no configuration available use toolchain definition.
+	 *
+	 * @param name - name of the variable.
+	 * @param toolChain - toolchain.
+	 * @param resolveMacros - {@code true} to expand macros, {@code false} otherwise.
+	 *
+	 * @return value of the variable.
+	 */
+	public String getVariableInConfigurationContext(String name, IToolChain toolChain, boolean resolveMacros) {
+		if (toolChain == null) {
+			return null;
+		}
+
+		IConfiguration cfg = toolChain.getParent();
+		ICConfigurationDescription cfgDescription = cfg != null ? ManagedBuildManager.getDescriptionForConfiguration(cfg) : null;
+
+		IEnvironmentVariable var = null;
+		if (cfgDescription != null) {
+			var = getVariable(name, cfgDescription, resolveMacros);
+		} else {
+			var = getVariable(name, toolChain, resolveMacros);
+		}
+
+		String value = var != null ? var.getValue() : null;
+		return value;
+	}
+
+}
diff --git a/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/cygwin/CygwinPathResolver.java b/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/cygwin/CygwinPathResolver.java
index 8f2b5b7e781..f3e5dc9e034 100644
--- a/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/cygwin/CygwinPathResolver.java
+++ b/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/cygwin/CygwinPathResolver.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2005, 2010 Intel Corporation and others.
+ * Copyright (c) 2005, 2013 Intel Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -9,6 +9,7 @@
  *     Intel Corporation - Initial API and implementation
  *     Enrico Ehrich - http://bugs.eclipse.org/233866
  *     Marc-Andre Laperle - fix for Cygwin GCC is Not detected (bug 303900)
+ *     Andrew Gvozdev - changes to recognize $CYGWIN_HOME
  *******************************************************************************/
 package org.eclipse.cdt.managedbuilder.gnu.cygwin;
 
@@ -19,9 +20,8 @@ import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.util.ArrayList;
 
-import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.envvar.IEnvironmentVariable;
-import org.eclipse.cdt.core.settings.model.util.CDataUtil;
+import org.eclipse.cdt.internal.core.Cygwin;
 import org.eclipse.cdt.managedbuilder.core.IBuildPathResolver;
 import org.eclipse.cdt.managedbuilder.core.IConfiguration;
 import org.eclipse.cdt.managedbuilder.core.ManagedBuildManager;
@@ -30,40 +30,35 @@ import org.eclipse.cdt.utils.PathUtil;
 import org.eclipse.cdt.utils.WindowsRegistry;
 import org.eclipse.cdt.utils.spawner.ProcessFactory;
 import org.eclipse.core.runtime.IPath;
+import org.eclipse.core.runtime.IStatus;
+import org.eclipse.core.runtime.Status;
 
 /**
  * @noextend This class is not intended to be subclassed by clients.
  */
 public class CygwinPathResolver implements IBuildPathResolver {
-	private static final String DEFAULT_ROOT = "C:\\cygwin"; //$NON-NLS-1$
-	private static final String TOOL = "/cygpath -w -p "; //$NON-NLS-1$
-	private static final char BS = '\\';
-	private static final char SLASH = '/';
+	private static final String ENV_PATH = "PATH"; //$NON-NLS-1$
+	private static final String DELIMITER_UNIX = ":";    //$NON-NLS-1$
+	private static final String DELIMITER_WIN  = ";";    //$NON-NLS-1$
+
 	private static final String PROPERTY_OS_NAME = "os.name"; //$NON-NLS-1$
-	private static final String PROPERTY_OS_VALUE = "windows";//$NON-NLS-1$
-	private static final String SP = " ";         //$NON-NLS-1$
-	private static final String REGISTRY_KEY_SETUP = "SOFTWARE\\Cygwin\\setup"; //$NON-NLS-1$
-	private static final String REGISTRY_KEY_SETUP_WIN64 = "SOFTWARE\\Wow6432Node\\Cygwin\\setup"; //$NON-NLS-1$
+	private static final String OS_WINDOWS = "windows";//$NON-NLS-1$
+	private static final char SLASH = '/';
+	private static final char BACKSLASH = '\\';
+
+	private static final String CYGPATH_PATH_LIST_TO_WINDOWS = "cygpath -w -p "; //$NON-NLS-1$
+
 	// note that in Cygwin 1.7 the mount point storage has been moved out of the registry
 	private static final String REGISTRY_KEY_MOUNTS = "SOFTWARE\\Cygnus Solutions\\Cygwin\\mounts v2\\"; //$NON-NLS-1$
 	private static final String PATH_NAME = "native";   //$NON-NLS-1$
-	private static final String SSLASH = "/";           //$NON-NLS-1$
-	private static final String BSLASH = "\\\\";        //$NON-NLS-1$
 	private static final String BINPATTERN = "/usr/bin"; //$NON-NLS-1$
 	private static final String BINPATTERN_ALTERNATE = "/bin"; //$NON-NLS-1$
 	private static final String ETCPATTERN = "/etc";     //$NON-NLS-1$
-	private static final String ROOTPATTERN = SSLASH;
-	private static final String DELIMITER_UNIX = ":";    //$NON-NLS-1$
-	private static final String DELIMITER_WIN  = ";";    //$NON-NLS-1$
+
 	private static final String GCC_VERSION_CMD  = "gcc --version";    //$NON-NLS-1$
 	private static final String MINGW_SPECIAL = "mingw ";    //$NON-NLS-1$
 	private static final String CYGWIN_SPECIAL = "cygwin ";    //$NON-NLS-1$
 
-	private static String envPathValueCached = null;
-	private static String binCygwin  = null;
-	private static String rootCygwin = null;
-	private static String etcCygwin = null;
-
 	@Override
 	public String[] resolveBuildPaths(int pathType, String variableName, String variableValue, IConfiguration configuration) {
 		if(!isWindows()) {
@@ -72,58 +67,66 @@ public class CygwinPathResolver implements IBuildPathResolver {
 			return variableValue.split(DELIMITER_WIN);
 		}
 
-		String[] result = variableValue.split(DELIMITER_UNIX);
-		String exePath = getBinPath();
-		if (exePath == null) {
-			return result; // no changes
-		}
-		File file = new File(exePath);
-		if (!file.exists() || !file.isDirectory()) {
-			return result; // no changes
-		}
-		String s = exePath + TOOL + variableValue;
-		String[] lines = exec(s, configuration);
+		String[] lines = executeInConfigurationContext(CYGPATH_PATH_LIST_TO_WINDOWS + variableValue, configuration);
 		if (lines != null && lines.length > 0) {
-			result = lines[0].replace(BS,SLASH).split(DELIMITER_WIN);
+			String pathList = lines[0].replace(BACKSLASH, SLASH);
+			return pathList.split(DELIMITER_WIN);
 		}
-		return result;
+
+		return variableValue.split(DELIMITER_UNIX);
 	}
 
 	/**
-	 * returns "/etc" path in Windows format
+	 * @return "/etc" path in Windows format for workspace.
+	 * @deprecated. Deprecated as of CDT 8.2. Note that Cygwin root path in general may depend on configuration.
 	 *
 	 * If you use this do not cache results to ensure user preferences are accounted for.
 	 * Please rely on internal caching.
 	 */
+	@Deprecated
 	public static String getEtcPath() {
-		findPaths();
+		String etcCygwin = getPathFromRoot(ETCPATTERN);
+		// Try to find the paths in SOFTWARE\\Cygnus Solutions
+		if(etcCygwin == null) {
+			etcCygwin = readValueFromRegistry(REGISTRY_KEY_MOUNTS + ETCPATTERN, PATH_NAME);
+		}
 		return etcCygwin;
 	}
 
 	/**
-	 * returns "/usr/bin" path in Windows format
+	 * @return "/usr/bin" path in Windows format for workspace.
+	 * @deprecated. Deprecated as of CDT 8.2. Note that Cygwin root path in general may depend on configuration.
 	 *
 	 * If you use this do not cache results to ensure user preferences are accounted for.
 	 * Please rely on internal caching.
 	 */
+	@Deprecated
 	public static String getBinPath() {
-		findPaths();
+		String binCygwin = getPathFromRoot(BINPATTERN);
+		if(binCygwin == null) {
+			binCygwin = getPathFromRoot(BINPATTERN_ALTERNATE);
+		}
+		// Try to find the paths in SOFTWARE\\Cygnus Solutions
+		if(binCygwin == null) {
+			binCygwin = readValueFromRegistry(REGISTRY_KEY_MOUNTS + BINPATTERN, PATH_NAME);
+		}
 		return binCygwin;
 	}
 
 	/**
-	 * returns Cygwin root ("/") path in Windows format
+	 * @return Cygwin root ("/") path in Windows format for workspace.
+	 * @deprecated. Deprecated as of CDT 8.2. Note that Cygwin root path in general may depend on configuration.
 	 *
 	 * If you use this do not cache results to ensure user preferences are accounted for.
 	 * Please rely on internal caching.
 	 */
+	@Deprecated
 	public static String getRootPath() {
-		findPaths();
-		return rootCygwin;
+		return Cygwin.getCygwinHome();
 	}
 
 	public static boolean isWindows() {
-		return (System.getProperty(PROPERTY_OS_NAME).toLowerCase().startsWith(PROPERTY_OS_VALUE));
+		return (System.getProperty(PROPERTY_OS_NAME).toLowerCase().startsWith(OS_WINDOWS));
 	}
 
 	/**
@@ -136,146 +139,117 @@ public class CygwinPathResolver implements IBuildPathResolver {
 	 */
 	private static String readValueFromRegistry(String key, String name) {
 		WindowsRegistry registry = WindowsRegistry.getRegistry();
-		if (null != registry) {
-			String s = registry.getCurrentUserValue(key, name);
-			if(s == null)
-				s = registry.getLocalMachineValue(key, name);
-
-			if (s != null)
-				return (s.replaceAll(BSLASH, SSLASH));
+		if (registry != null) {
+			String value = registry.getCurrentUserValue(key, name);
+			if (value == null) {
+				value = registry.getLocalMachineValue(key, name);
+			}
+			if (value != null) {
+				return value.replace(BACKSLASH, SLASH);
+			}
 		}
 		return null;
 	}
 
 	/**
-	 *  Returns the absolute path of the pattern by
-	 *  simply appending the pattern to the root
+	 * Returns the absolute path of the pattern by simply appending the relativePath to the root.
 	 *
-	 * @param pattern The pattern to find
-	 * @return The absolute path to the pattern or null if pattern is not found
+	 * @param relativePath - the pattern to find.
+	 * @return The absolute path to the pattern or {@code null} if path does not exist.
 	 */
-	private static String getValueFromRoot(String pattern) {
+	private static String getPathFromRoot(String relativePath) {
+		String rootCygwin = Cygwin.getCygwinHome();
 		if (rootCygwin != null) {
-			String path = rootCygwin + pattern;
+			String path = rootCygwin + relativePath;
 			File file = new File(path);
-			if (file.exists() && file.isDirectory())
-				return (path.replaceAll(BSLASH, SSLASH));
-			else
-				return null;
+			if (file.exists() && file.isDirectory()) {
+				return path.replace(BACKSLASH, SLASH);
+			}
 		}
-
 		return null;
 	}
 
 	/**
-	 * Returns the absolute path to cygwin's root
+	 * Resolve and return full path to program in context of configuration.
 	 *
-	 * @return The absolute path to cygwin's root or null if not found
+	 * @param program - program to resolve.
+	 * @param cfg - configuration context.
+	 * @return absolute path to program.
 	 */
-	private static String findRoot(String paths) {
-		String rootValue = null;
-
-		// 1. Look in PATH values. Look for bin\cygwin1.dll
-		IPath location = PathUtil.findProgramLocation("cygwin1.dll", paths); //$NON-NLS-1$
-		if (location!=null) {
-			rootValue = location.removeLastSegments(2).toOSString();
-		}
-
-		// 2. Try to find the root dir in SOFTWARE\Cygwin\setup
-		if(rootValue == null) {
-			rootValue = readValueFromRegistry(REGISTRY_KEY_SETUP, "rootdir"); //$NON-NLS-1$
-		}
-
-		// 3. Try to find the root dir in SOFTWARE\Wow6432Node\Cygwin\setup
-		if(rootValue == null) {
-			rootValue = readValueFromRegistry(REGISTRY_KEY_SETUP_WIN64, "rootdir"); //$NON-NLS-1$
-		}
-
-		// 4. Try to find the root dir in SOFTWARE\Cygnus Solutions
-		if (rootValue == null) {
-			rootValue = readValueFromRegistry(REGISTRY_KEY_MOUNTS + ROOTPATTERN, PATH_NAME);
-		}
-
-		// 5. Try the default Cygwin install dir
-		if(rootValue == null) {
-			File file = new File(DEFAULT_ROOT);
-			if (file.exists() && file.isDirectory())
-				rootValue = DEFAULT_ROOT;
+	private static String resolveProgram(String program, IConfiguration cfg) {
+		String envPathValue = null;
+		try {
+			IEnvironmentVariable envPathVar = ManagedBuildManager.getEnvironmentVariableProvider().getVariable(ENV_PATH, cfg, true);
+			if (envPathVar != null) {
+				envPathValue = envPathVar.getValue();
+				IPath progPath = PathUtil.findProgramLocation(program, envPathValue);
+				if (progPath != null) {
+					program = progPath.toOSString();
+				}
+				// this resolves cygwin symbolic links
+				program = Cygwin.cygwinToWindowsPath(program, envPathValue);
+			}
+		} catch (Exception e) {
+			GnuUIPlugin.getDefault().log(new Status(IStatus.WARNING, GnuUIPlugin.PLUGIN_ID, "Problem trying to find program [" + program + "] in $PATH=[" + envPathValue + "]", e));
 		}
-
-		if(rootValue != null)
-			rootValue = rootValue.replaceAll(BSLASH, SSLASH);
-
-		return rootValue;
+		return program;
 	}
 
 	/**
-	 * Finds Cygwin's paths and sets corresponding properties.
+	 * Return environment in envp format, see {@link Runtime#exec(String, String[])}.
+	 *
+	 * @param cfg - configuration.
+	 * @return environment as array of strings in format name=value.
 	 */
-	private static synchronized void findPaths() {
-		if (!isWindows()) {
-			return;
+	private static String[] getEnvp(IConfiguration cfg) {
+		IEnvironmentVariable vars[] = ManagedBuildManager.getEnvironmentVariableProvider().getVariables(cfg,true);
+		String envp[] = new String[vars.length];
+		for(int i = 0; i < envp.length; i++) {
+			envp[i] = vars[i].getName() +'=';
+			String value = vars[i].getValue();
+			if(value != null)
+				envp[i] += value;
 		}
-
-		IEnvironmentVariable varPath = CCorePlugin.getDefault().getBuildEnvironmentManager().getVariable("PATH", null, true); //$NON-NLS-1$
-		String envPathValue = varPath != null ? varPath.getValue() : null;
-
-		if (CDataUtil.objectsEqual(envPathValue, envPathValueCached)) {
-			return;
-		}
-
-		etcCygwin  = null;
-		binCygwin  = null;
-		rootCygwin = null;
-
-		rootCygwin = findRoot(envPathValue);
-
-		// 1. Try to find the paths by appending the patterns to the root dir
-		etcCygwin = getValueFromRoot(ETCPATTERN);
-		binCygwin = getValueFromRoot(BINPATTERN);
-		if(binCygwin == null)
-			binCygwin = getValueFromRoot(BINPATTERN_ALTERNATE);
-
-		// 2. Try to find the paths in SOFTWARE\\Cygnus Solutions
-		if(etcCygwin == null)
-			etcCygwin = readValueFromRegistry(REGISTRY_KEY_MOUNTS + ETCPATTERN, PATH_NAME);
-		if(binCygwin == null)
-			binCygwin = readValueFromRegistry(REGISTRY_KEY_MOUNTS + BINPATTERN, PATH_NAME);
-
-		envPathValueCached = envPathValue;
+		return envp;
 	}
 
-	private static String[] exec(String cmd, IConfiguration cfg) {
+	/**
+	 * Execute command taking in account configuration environment.
+	 *
+	 * @param cmd - command to execute.
+	 * @param cfg - configuration context.
+	 * @return command output as string array.
+	 */
+	private static String[] executeInConfigurationContext(String cmd, IConfiguration cfg) {
+		String[] args = cmd.split(" "); //$NON-NLS-1$
+		args[0] = resolveProgram(args[0], cfg);
+
+		String[] result = null;
 		try {
-			IEnvironmentVariable vars[] = ManagedBuildManager.getEnvironmentVariableProvider().getVariables(cfg,true);
-			String env[] = new String[vars.length];
-			for(int i = 0; i < env.length; i++) {
-				env[i] = vars[i].getName() + "="; //$NON-NLS-1$
-				String value = vars[i].getValue();
-				if(value != null)
-					env[i] += value;
-			}
-			Process proc = ProcessFactory.getFactory().exec(cmd.split(SP), env);
+			String[] envp = getEnvp(cfg);
+			Process proc = ProcessFactory.getFactory().exec(args, envp);
 			if (proc != null) {
-
 				InputStream ein = proc.getInputStream();
-				BufferedReader d1 = new BufferedReader(new InputStreamReader(ein));
-				ArrayList<String> ls = new ArrayList<String>(10);
-				String s;
-				while ((s = d1.readLine() ) != null ) {
-					ls.add(s);
+				try {
+					BufferedReader d1 = new BufferedReader(new InputStreamReader(ein));
+					ArrayList<String> ls = new ArrayList<String>(10);
+					String s;
+					while ((s = d1.readLine()) != null ) {
+						ls.add(s);
+					}
+					result = ls.toArray(new String[0]);
+				} finally {
+					ein.close();
 				}
-				ein.close();
-				return ls.toArray(new String[0]);
 			}
 		} catch (IOException e) {
-			GnuUIPlugin.getDefault().log(e);
+			GnuUIPlugin.getDefault().log(new Status(IStatus.ERROR, GnuUIPlugin.PLUGIN_ID, "Error executing program [" +cmd + "]", e));
 		}
-		return null;
+		return result;
 	}
 
 	public static boolean isMinGW(IConfiguration cfg) {
-		String versionInfo[] = exec(GCC_VERSION_CMD, cfg);
+		String versionInfo[] = executeInConfigurationContext(GCC_VERSION_CMD, cfg);
 		if(versionInfo != null) {
 			for(int i = 0; i < versionInfo.length; i++) {
 				if(versionInfo[i].indexOf(MINGW_SPECIAL) != -1)
diff --git a/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/cygwin/GnuCygwinConfigurationEnvironmentSupplier.java b/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/cygwin/GnuCygwinConfigurationEnvironmentSupplier.java
index ae08fcf841d..5b659ead2d2 100644
--- a/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/cygwin/GnuCygwinConfigurationEnvironmentSupplier.java
+++ b/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/cygwin/GnuCygwinConfigurationEnvironmentSupplier.java
@@ -1,33 +1,38 @@
 /*******************************************************************************
- * Copyright (c) 2005, 2011 Intel Corporation and others.
+ * Copyright (c) 2005, 2012 Intel Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
- * Intel Corporation - Initial API and implementation
+ *     Intel Corporation - Initial API and implementation
+ *     Andrew Gvozdev    - Ability to use different Cygwin versions in different cfg
  *******************************************************************************/
 package org.eclipse.cdt.managedbuilder.gnu.cygwin;
 
+import org.eclipse.cdt.core.CCorePlugin;
+import org.eclipse.cdt.core.envvar.IEnvironmentVariable;
+import org.eclipse.cdt.internal.core.Cygwin;
 import org.eclipse.cdt.managedbuilder.core.IConfiguration;
 import org.eclipse.cdt.managedbuilder.envvar.IBuildEnvironmentVariable;
 import org.eclipse.cdt.managedbuilder.envvar.IConfigurationEnvironmentVariableSupplier;
 import org.eclipse.cdt.managedbuilder.envvar.IEnvironmentVariableProvider;
 import org.eclipse.cdt.managedbuilder.internal.envvar.BuildEnvVar;
+import org.eclipse.core.runtime.IPath;
+import org.eclipse.core.runtime.Path;
 
 /**
  * @noextend This class is not intended to be subclassed by clients.
  */
 public class GnuCygwinConfigurationEnvironmentSupplier implements IConfigurationEnvironmentVariableSupplier {
-	private static final String PATH = "PATH"; //$NON-NLS-1$
-	private static final String DELIMITER_UNIX = ":"; //$NON-NLS-1$
-	private static final String PROPERTY_DELIMITER = "path.separator"; //$NON-NLS-1$
-	private static final String PROPERTY_OSNAME = "os.name"; //$NON-NLS-1$
+	private static final String ENV_PATH = "PATH"; //$NON-NLS-1$
+	private static final String ENV_LANG = "LANG"; //$NON-NLS-1$
+	private static final String ENV_LC_ALL = "LC_ALL"; //$NON-NLS-1$
+	private static final String ENV_LC_MESSAGES = "LC_MESSAGES"; //$NON-NLS-1$
 
-	private static final String LANG = "LANG"; //$NON-NLS-1$
-	private static final String LC_ALL = "LC_ALL"; //$NON-NLS-1$
-	private static final String LC_MESSAGES = "LC_MESSAGES"; //$NON-NLS-1$
+	private static final String PROPERTY_OSNAME = "os.name"; //$NON-NLS-1$
+	private static final String BACKSLASH = java.io.File.separator;
 
 	@Override
 	public IBuildEnvironmentVariable getVariable(String variableName, IConfiguration configuration, IEnvironmentVariableProvider provider) {
@@ -39,19 +44,33 @@ public class GnuCygwinConfigurationEnvironmentSupplier implements IConfiguration
 			return null;
 		}
 
-		if (variableName.equalsIgnoreCase(PATH)) {
-			String p = CygwinPathResolver.getBinPath();
-			if (p != null) {
-				return new BuildEnvVar(PATH, p.replace('/','\\'), IBuildEnvironmentVariable.ENVVAR_PREPEND, System.getProperty(PROPERTY_DELIMITER, DELIMITER_UNIX));
+		if (variableName.equalsIgnoreCase(ENV_PATH)) {
+			@SuppressWarnings("nls")
+			String path = "${" + Cygwin.ENV_CYGWIN_HOME + "}" + BACKSLASH + "bin";
+			return new BuildEnvVar(ENV_PATH, path, IBuildEnvironmentVariable.ENVVAR_PREPEND);
+
+		} else if (variableName.equals(Cygwin.ENV_CYGWIN_HOME)) {
+			String home = Cygwin.getCygwinHome();
+			// If the variable is not defined still show it in the environment variables list as a hint to user
+			if (home == null) {
+				home = ""; //$NON-NLS-1$
+			}
+			IPath homePath = new Path(home);
+			IEnvironmentVariable varCygwinHome = CCorePlugin.getDefault().getBuildEnvironmentManager().getVariable(Cygwin.ENV_CYGWIN_HOME, null, false);
+			if (varCygwinHome == null || (!homePath.equals(new Path(varCygwinHome.getValue())))) {
+				// Contribute if the variable does not already come from workspace environment
+				return new BuildEnvVar(Cygwin.ENV_CYGWIN_HOME, homePath.toOSString());
 			}
-		} else if (variableName.equalsIgnoreCase(LANG)) {
+			return null;
+
+		} else if (variableName.equalsIgnoreCase(ENV_LANG)) {
 			// Workaround for not being able to select encoding for CDT console -> change codeset to Latin1
-			String langValue = System.getenv(LANG);
+			String langValue = System.getenv(ENV_LANG);
 			if (langValue == null || langValue.length() == 0) {
-				langValue = System.getenv(LC_ALL);
+				langValue = System.getenv(ENV_LC_ALL);
 			}
 			if (langValue == null || langValue.length() == 0) {
-				langValue = System.getenv(LC_MESSAGES);
+				langValue = System.getenv(ENV_LC_MESSAGES);
 			}
 			if (langValue != null && langValue.length() > 0) {
 				// langValue is [language[_territory][.codeset][@modifier]], i.e. "en_US.UTF-8@dict"
@@ -61,21 +80,17 @@ public class GnuCygwinConfigurationEnvironmentSupplier implements IConfiguration
 			} else {
 				langValue = "C.ISO-8859-1"; //$NON-NLS-1$
 			}
-
-			return new BuildEnvVar(LANG, langValue);
+			return new BuildEnvVar(ENV_LANG, langValue);
 		}
 		return null;
 	}
 
 	@Override
 	public IBuildEnvironmentVariable[] getVariables(IConfiguration configuration, IEnvironmentVariableProvider provider) {
-		IBuildEnvironmentVariable varLang = getVariable(LANG, configuration, provider);
-		IBuildEnvironmentVariable varPath = getVariable(PATH, configuration, provider);
+		IBuildEnvironmentVariable varHome = getVariable(Cygwin.ENV_CYGWIN_HOME, configuration, provider);
+		IBuildEnvironmentVariable varLang = getVariable(ENV_LANG, configuration, provider);
+		IBuildEnvironmentVariable varPath = getVariable(ENV_PATH, configuration, provider);
 
-		if (varPath != null) {
-			return new IBuildEnvironmentVariable[] {varLang, varPath};
-		} else {
-			return new IBuildEnvironmentVariable[] {varLang};
-		}
+		return new IBuildEnvironmentVariable[] {varHome, varLang, varPath};
 	}
 }
diff --git a/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/cygwin/IsGnuCygwinToolChainSupported.java b/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/cygwin/IsGnuCygwinToolChainSupported.java
index a2d2050338a..9a2fd648827 100644
--- a/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/cygwin/IsGnuCygwinToolChainSupported.java
+++ b/build/org.eclipse.cdt.managedbuilder.gnu.ui/src/org/eclipse/cdt/managedbuilder/gnu/cygwin/IsGnuCygwinToolChainSupported.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2005, 2010 Intel Corporation and others.
+ * Copyright (c) 2005, 2013 Intel Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -7,85 +7,28 @@
  *
  * Contributors:
  * Intel Corporation - Initial API and implementation
+ * Andrew Gvozdev    - Ability to use different Cygwin versions in different configurations
  *******************************************************************************/
 package org.eclipse.cdt.managedbuilder.gnu.cygwin;
 
-import java.io.BufferedReader;
-import java.io.File;
-import java.io.FileNotFoundException;
-import java.io.FileReader;
-import java.io.IOException;
-
-import org.eclipse.cdt.core.settings.model.util.CDataUtil;
+import org.eclipse.cdt.internal.core.Cygwin;
 import org.eclipse.cdt.managedbuilder.core.IManagedIsToolChainSupported;
 import org.eclipse.cdt.managedbuilder.core.IToolChain;
+import org.eclipse.cdt.managedbuilder.internal.envvar.EnvironmentVariableManagerToolChain;
 import org.osgi.framework.Version;
 
 /**
  * This class implements the IManagedIsToolChainSupported for the Gnu Cygwin tool-chain
- * The class is NOT used currently, because currently the gnu cygwin tool-chain
- * is intended to be used not only with Cygwin, but with MinGW also, and there is no
- * correct way of determining whether the appropriate packages are installed for MinGW.
- *
- * For the future MBS/CDT versions we might create the separate tool-chain/configuration/project-type
- * for the MinGW and define a set of converters using the tool-chain converter mechanism that MBS will provide,
- * that would convert the CygWin to the MinGW projects/tool-chains, and vice a versa.
  *
  * @noextend This class is not intended to be subclassed by clients.
  */
 public class IsGnuCygwinToolChainSupported implements IManagedIsToolChainSupported {
-	private static final String[] CHECKED_NAMES = {"gcc", "binutils", "make"};  //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
+	private static final String ENV_PATH = "PATH"; //$NON-NLS-1$
 
-	private static String etcCygwinCached = null;
-	private static boolean toolchainIsSupported = false;
-
-	/**
-	 * @since 8.0
-	 */
 	@Override
 	public boolean isSupported(IToolChain toolChain, Version version, String instance) {
-		String etcCygwin = CygwinPathResolver.getEtcPath();
-		if (CDataUtil.objectsEqual(etcCygwin, etcCygwinCached)) {
-			return toolchainIsSupported;
-		}
-
-		toolchainIsSupported = etcCygwin != null && arePackagesInstalled(etcCygwin);
-		etcCygwinCached = etcCygwin;
-
-		return toolchainIsSupported;
+		String envPath = EnvironmentVariableManagerToolChain.getDefault().getVariableInConfigurationContext(ENV_PATH, toolChain, true);
+		return Cygwin.isAvailable(envPath);
 	}
 
-	/**
-	 * Returns true if all required packages are installed, see CHECKED_NAMES for a list of packages. Cygwin
-	 * maintains a list of packages in /etc/setup/installed.db so we look for packages in this file.
-	 *
-	 * @param etcCygwin the absolute path of /etc containing /setup/installed.db
-	 * @return true if the packages specified in CHECKED_NAMES are installed
-	 */
-	private boolean arePackagesInstalled(String etcCygwin) {
-		boolean arePackagesInstalled = false;
-		File file = new File(etcCygwin + "/setup/installed.db"); //$NON-NLS-1$
-		try {
-			BufferedReader data = new BufferedReader(new FileReader(file));
-
-			// All required package names should be found
-			boolean[] found = new boolean[CHECKED_NAMES.length];
-			String s;
-			while ((s = data.readLine()) != null ) {
-				for (int j = 0; j < CHECKED_NAMES.length; j++) {
-					if (s.startsWith(CHECKED_NAMES[j])) {
-						found[j] = true;
-					}
-				}
-			}
-			arePackagesInstalled = true;
-			for (int j = 0; j < CHECKED_NAMES.length; j++) {
-				arePackagesInstalled &= found[j];
-			}
-			data.close();
-		} catch (FileNotFoundException e) {
-		} catch (IOException e) {
-		}
-		return arePackagesInstalled;
-	}
 }
diff --git a/core/org.eclipse.cdt.core/utils/org/eclipse/cdt/internal/core/Cygwin.java b/core/org.eclipse.cdt.core/utils/org/eclipse/cdt/internal/core/Cygwin.java
index e0b770d87c9..bd878b12cd7 100644
--- a/core/org.eclipse.cdt.core/utils/org/eclipse/cdt/internal/core/Cygwin.java
+++ b/core/org.eclipse.cdt.core/utils/org/eclipse/cdt/internal/core/Cygwin.java
@@ -1,5 +1,5 @@
 /*******************************************************************************

- * Copyright (c) 2012, 2012 Andrew Gvozdev and others.

+ * Copyright (c) 2012, 2013 Andrew Gvozdev and others.

  * All rights reserved. This program and the accompanying materials

  * are made available under the terms of the Eclipse Public License v1.0

  * which accompanies this distribution, and is available at

@@ -11,24 +11,74 @@
 package org.eclipse.cdt.internal.core;

 

 import java.io.BufferedReader;

+import java.io.File;

 import java.io.IOException;

 import java.io.InputStreamReader;

+import java.util.Collections;

+import java.util.Map;

 

+import org.eclipse.cdt.core.CCorePlugin;

+import org.eclipse.cdt.core.envvar.IEnvironmentVariable;

+import org.eclipse.cdt.core.settings.model.util.CDataUtil;

 import org.eclipse.cdt.utils.PathUtil;

+import org.eclipse.cdt.utils.WindowsRegistry;

 import org.eclipse.core.runtime.IPath;

+import org.eclipse.core.runtime.Path;

 import org.eclipse.core.runtime.Platform;

 

 /**

  * A collection of cygwin-related utilities.

  */

 public class Cygwin {

+	public static final String ENV_CYGWIN_HOME = "CYGWIN_HOME"; //$NON-NLS-1$

+	private static final String ENV_PATH = "PATH"; //$NON-NLS-1$

 

-	private static IPath findCygpathLocation(String envPath) {

-		return PathUtil.findProgramLocation("cygpath", envPath); //$NON-NLS-1$

+	private static final String CYGPATH = "cygpath"; //$NON-NLS-1$

+	private static final String DEFAULT_ROOT = "C:\\cygwin"; //$NON-NLS-1$

+	private static final String CYGWIN_DLL = "cygwin1.dll"; //$NON-NLS-1$

+	private static final String REGISTRY_KEY_SETUP = "SOFTWARE\\Cygwin\\setup"; //$NON-NLS-1$

+	private static final String REGISTRY_KEY_SETUP_WIN64 = "SOFTWARE\\Wow6432Node\\Cygwin\\setup"; //$NON-NLS-1$

+	// note that in Cygwin 1.7 the mount point storage has been moved out of the registry

+	private static final String REGISTRY_KEY_MOUNTS = "SOFTWARE\\Cygnus Solutions\\Cygwin\\mounts v2\\"; //$NON-NLS-1$

+	private static final String PATH_NAME = "native";   //$NON-NLS-1$

+	private static final String ROOTPATTERN = "/"; //$NON-NLS-1$

+	private static final char SLASH = '/';

+	private static final char BACKSLASH = '\\';

+

+	private static final boolean isWindowsPlatform = Platform.getOS().equals(Platform.OS_WIN32);

+

+	private static String envPathValueCached = null;

+	private static String envCygwinHomeValueCached = null;

+	private static String cygwinLocation = null;

+	private static boolean isCygwinLocationCached = false;

+

+	private final static Map<String/*envPath*/, String /*cygpathLocation*/> cygpathLocationCache = Collections.synchronizedMap(new LRUCache<String, String>(1,20));

+	private final static Map<String/*command*/, String /*translatedPath*/> translatedPathsCache = Collections.synchronizedMap(new LRUCache<String, String>(10,500));

+

+	/**

+	 * Find location of "cygpath" utility on the file system.

+	 */

+	private static String findCygpathLocation(String envPath) {

+		if (envPath == null) {

+			// $PATH from user preferences

+			IEnvironmentVariable varPath = CCorePlugin.getDefault().getBuildEnvironmentManager().getVariable(ENV_PATH, null, true);

+			if (varPath != null) {

+				envPath = varPath.getValue();

+			}

+		}

+

+		String cygpathLocation = cygpathLocationCache.get(envPath);

+		if (cygpathLocation == null) {

+			IPath loc = PathUtil.findProgramLocation(CYGPATH, envPath);

+			cygpathLocation = loc != null ? loc.toOSString() : null;

+			cygpathLocationCache.put(envPath, cygpathLocation);

+		}

+		return cygpathLocation;

 	}

 

 	/**

 	 * Check if cygwin path conversion utilities are available in the path.

+	 * Tells whether cygwin is installed in the path.

 	 *

 	 * @param envPath - list of directories to search for cygwin utilities separated

 	 *    by path separator (format of environment variable $PATH)

@@ -36,22 +86,60 @@ public class Cygwin {
 	 * @return {@code true} if cygwin is available, {@code false} otherwise.

 	 */

 	public static boolean isAvailable(String envPath) {

-		return Platform.getOS().equals(Platform.OS_WIN32) && findCygpathLocation(envPath) != null;

+		return isWindowsPlatform && findCygpathLocation(envPath) != null;

 	}

 

 	/**

 	 * Check if cygwin path conversion utilities are available in $PATH.

+	 * Tells whether cygwin is installed in the path.

 	 *

 	 * @return {@code true} if cygwin is available, {@code false} otherwise.

 	 */

 	public static boolean isAvailable() {

-		return Platform.getOS().equals(Platform.OS_WIN32) && findCygpathLocation(null) != null;

+		return isWindowsPlatform && findCygpathLocation(null) != null;

+	}

+

+	/**

+	 * Run program (assuming cygpath) and return the translated path which is the first line of output.

+	 */

+	private static String runCygpath(String[] args) throws IOException {

+		String command = getCommand(args);

+		String translatedPath = translatedPathsCache.get(command);

+		if (translatedPath == null) {

+			Process cygpathProcess = Runtime.getRuntime().exec(args);

+			BufferedReader stdout = new BufferedReader(new InputStreamReader(cygpathProcess.getInputStream()));

+			String firstLine = null;

+			try {

+				firstLine = stdout.readLine();

+			} finally {

+				stdout.close();

+			}

+			if (firstLine == null) {

+				throw new IOException("Unable read output from command=[" + command + "]"); //$NON-NLS-1$ //$NON-NLS-2$

+			}

+			translatedPath = firstLine.trim();

+			translatedPathsCache.put(command, translatedPath);

+		}

+

+		return translatedPath;

+	}

+

+	/**

+	 * Construct a command from arguments array.

+	 */

+	private static String getCommand(String[] args) {

+		String command = ""; //$NON-NLS-1$

+		for (String arg : args) {

+			command = command + arg + ' ';

+		}

+		return command.trim();

 	}

 

 	/**

 	 * Conversion from Cygwin path to Windows path.

+	 * Note that there is no need to cache results, they are already cached internally.

 	 *

-	 * @param cygwinPath - Cygwin path.

+	 * @param cygwinPath - cygwin path.

 	 * @param envPath - list of directories to search for cygwin utilities separated

 	 *    by path separator (format of environment variable $PATH).

 	 * @return Windows style converted path. Note that that also converts cygwin links to their targets.

@@ -63,31 +151,24 @@ public class Cygwin {
 		if (cygwinPath == null || cygwinPath.trim().length() == 0)

 			return cygwinPath;

 

-		if (!Platform.getOS().equals(Platform.OS_WIN32)) {

-			// Don't run this on non-windows platforms

+		if (!isWindowsPlatform) {

 			throw new UnsupportedOperationException("Not a Windows system, Cygwin is unavailable."); //$NON-NLS-1$

 		}

 

-		IPath cygpathLocation = findCygpathLocation(envPath);

+		String cygpathLocation = findCygpathLocation(envPath);

 		if (cygpathLocation == null) {

-			throw new UnsupportedOperationException("Cygwin utility cygpath is not in the system search path."); //$NON-NLS-1$

+			throw new UnsupportedOperationException(CYGPATH + " is not in the system search path."); //$NON-NLS-1$

 		}

 

-		String[] args = {cygpathLocation.toOSString(), "-w", cygwinPath}; //$NON-NLS-1$

-		Process cygpathProcess = Runtime.getRuntime().exec(args);

-		BufferedReader stdout = new BufferedReader(new InputStreamReader(cygpathProcess.getInputStream()));

-

-		String windowsPath = stdout.readLine();

-		if (windowsPath == null) {

-			throw new IOException("Unexpected output from Cygwin utility cygpath."); //$NON-NLS-1$

-		}

-		return windowsPath.trim();

+		String windowsPath = runCygpath(new String[] {cygpathLocation, "-w", cygwinPath}); //$NON-NLS-1$

+		return windowsPath;

 	}

 

 	/**

 	 * Conversion from Cygwin path to Windows path.

+	 * Note that there is no need to cache results, they are already cached internally.

 	 *

-	 * @param cygwinPath - Cygwin path.

+	 * @param cygwinPath - cygwin path.

 	 * @return Windows style converted path. Note that that also converts cygwin links to their targets.

 	 *

 	 * @throws UnsupportedOperationException if Cygwin is unavailable.

@@ -99,6 +180,7 @@ public class Cygwin {
 

 	/**

 	 * Conversion from Windows path to Cygwin path.

+	 * Note that there is no need to cache results, they are already cached internally.

 	 *

 	 * @param windowsPath - Windows path.

 	 * @param envPath - list of directories to search for cygwin utilities (value of environment variable $PATH).

@@ -111,28 +193,22 @@ public class Cygwin {
 		if (windowsPath == null || windowsPath.trim().length() == 0)

 			return windowsPath;

 

-		if (!Platform.getOS().equals(Platform.OS_WIN32)) {

-			// Don't run this on non-windows platforms

+		if (!isWindowsPlatform) {

 			throw new UnsupportedOperationException("Not a Windows system, Cygwin is unavailable."); //$NON-NLS-1$

 		}

-		IPath cygpathLocation = findCygpathLocation(envPath);

+

+		String cygpathLocation = findCygpathLocation(envPath);

 		if (cygpathLocation == null) {

-			throw new UnsupportedOperationException("Cygwin utility cygpath is not in the system search path."); //$NON-NLS-1$

+			throw new UnsupportedOperationException(CYGPATH + " is not in the system search path."); //$NON-NLS-1$

 		}

 

-		String[] args = {cygpathLocation.toOSString(), "-u", windowsPath}; //$NON-NLS-1$

-		Process cygpath = Runtime.getRuntime().exec(args);

-		BufferedReader stdout = new BufferedReader(new InputStreamReader(cygpath.getInputStream()));

-

-		String cygwinPath = stdout.readLine();

-		if (cygwinPath == null) {

-			throw new IOException("Unexpected output from Cygwin utility cygpath."); //$NON-NLS-1$

-		}

-		return cygwinPath.trim();

+		String cygwinPath = runCygpath(new String[] {cygpathLocation, "-u", windowsPath}); //$NON-NLS-1$

+		return cygwinPath;

 	}

 

 	/**

 	 * Conversion from Windows path to Cygwin path.

+	 * Note that there is no need to cache results, they are already cached internally.

 	 *

 	 * @param windowsPath - Windows path.

 	 * @return Cygwin style converted path.

@@ -143,4 +219,114 @@ public class Cygwin {
 	public static String windowsToCygwinPath(String windowsPath) throws IOException, UnsupportedOperationException {

 		return windowsToCygwinPath(windowsPath, null);

 	}

+

+	/**

+	 * Find location where Cygwin is installed. A number of locations is being checked,

+	 * such as environment variable $CYGWIN_HOME, $PATH, Windows registry et al.

+	 * <br><br>

+	 * If you use this do not cache results to ensure user preferences are accounted for.

+	 * Please rely on internal caching.

+	 * 

+	 * @return Location of Cygwin root folder "/" on file system in Windows format.

+	 */

+	public static String getCygwinHome() {

+		if (!isWindowsPlatform) {

+			return null;

+		}

+

+		IEnvironmentVariable varPath = CCorePlugin.getDefault().getBuildEnvironmentManager().getVariable(ENV_PATH, null, true);

+		String envPathValue = varPath != null ? varPath.getValue() : null;

+		IEnvironmentVariable varCygwinHome = CCorePlugin.getDefault().getBuildEnvironmentManager().getVariable(ENV_CYGWIN_HOME, null, true);

+		String envCygwinHomeValue = varCygwinHome != null ? varCygwinHome.getValue() : null;

+

+		 // isCygwinLocationCached is used to figure fact of caching when all cached objects are null

+		if (isCygwinLocationCached && CDataUtil.objectsEqual(envPathValue, envPathValueCached) && CDataUtil.objectsEqual(envCygwinHomeValue, envCygwinHomeValueCached)) {

+			return cygwinLocation;

+		}

+

+		cygwinLocation = findCygwinRoot(envPathValue, envCygwinHomeValue);

+

+		envPathValueCached = envPathValue;

+		envCygwinHomeValueCached = envCygwinHomeValue;

+		isCygwinLocationCached = true;

+		

+		return cygwinLocation;

+	}

+

+	/**

+	 * Reads required value from registry. Looks in both

+	 * HKEY_CURRENT_USER and HKEY_LOCAL_MACHINE

+	 *

+	 * @param key Registry key

+	 * @param name Registry value to read

+	 * @return corresponding string value or null if nothing found

+	 */

+	private static String readValueFromRegistry(String key, String name) {

+		WindowsRegistry registry = WindowsRegistry.getRegistry();

+		if (registry != null) {

+			String s = registry.getCurrentUserValue(key, name);

+			if(s == null) {

+				s = registry.getLocalMachineValue(key, name);

+			}

+

+			if (s != null) {

+				return (s.replace(BACKSLASH, SLASH));

+			}

+		}

+		return null;

+	}

+

+	/**

+	 * @return The absolute path to cygwin's root or null if not found

+	 */

+	private static String findCygwinRoot(String envPathValue, String envCygwinHomeValue) {

+		String rootValue = null;

+

+		// Check $CYGWIN_HOME

+		if (envCygwinHomeValue != null && !envCygwinHomeValue.isEmpty()) {

+			IPath location = new Path(envCygwinHomeValue + "/bin/" + CYGWIN_DLL); //$NON-NLS-1$

+			if (location.toFile().exists()) {

+				// get rootValue from "rootValue\bin\cygwin1.dll"

+				rootValue = location.removeLastSegments(2).toOSString();

+			}

+		}

+

+		// Look in PATH values. Look for cygwin1.dll

+		if(rootValue == null) {

+			IPath location = PathUtil.findProgramLocation(CYGWIN_DLL, envPathValue);

+			if (location != null) {

+				// get rootValue from "rootValue\bin\cygwin1.dll"

+				rootValue = location.removeLastSegments(2).toOSString();

+			}

+		}

+

+		// Try to find the root dir in SOFTWARE\Cygwin\setup

+		if(rootValue == null) {

+			rootValue = readValueFromRegistry(REGISTRY_KEY_SETUP, "rootdir"); //$NON-NLS-1$

+		}

+

+		// Try to find the root dir in SOFTWARE\Wow6432Node\Cygwin\setup

+		if(rootValue == null) {

+			rootValue = readValueFromRegistry(REGISTRY_KEY_SETUP_WIN64, "rootdir"); //$NON-NLS-1$

+		}

+

+		// Try to find the root dir in SOFTWARE\Cygnus Solutions

+		if (rootValue == null) {

+			rootValue = readValueFromRegistry(REGISTRY_KEY_MOUNTS + ROOTPATTERN, PATH_NAME);

+		}

+

+		// Try the default Cygwin install dir

+		if(rootValue == null) {

+			File file = new File(DEFAULT_ROOT);

+			if (file.exists() && file.isDirectory())

+				rootValue = DEFAULT_ROOT;

+		}

+

+		if(rootValue != null) {

+			rootValue = rootValue.replace(BACKSLASH, SLASH);

+		}

+

+		return rootValue;

+	}

+

 }

diff --git a/core/org.eclipse.cdt.core/utils/org/eclipse/cdt/internal/core/LRUCache.java b/core/org.eclipse.cdt.core/utils/org/eclipse/cdt/internal/core/LRUCache.java
new file mode 100644
index 00000000000..817613c6406
--- /dev/null
+++ b/core/org.eclipse.cdt.core/utils/org/eclipse/cdt/internal/core/LRUCache.java
@@ -0,0 +1,50 @@
+/*******************************************************************************

+ * Copyright (c) 2013 Andrew Gvozdev and others.

+ * All rights reserved. This program and the accompanying materials

+ * are made available under the terms of the Eclipse Public License v1.0

+ * which accompanies this distribution, and is available at

+ * http://www.eclipse.org/legal/epl-v10.html

+ *

+ * Contributors:

+ *    Andrew Gvozdev - initial API and implementation

+ *******************************************************************************/ 

+

+package org.eclipse.cdt.internal.core;

+

+import java.util.LinkedHashMap;

+import java.util.Map.Entry;

+

+/**

+ * A simple cache with limited number of items in the cache. LRUCache discards the Least Recently Used items first.

+ * Based on {@link LinkedHashMap}. Note that {@link LinkedHashMap} has built-in facility to support cache like that

+ * which is described in its JavaDoc.

+ */

+public class LRUCache<K, V> extends LinkedHashMap<K, V> {

+	private int fLimit;

+

+	/**

+	 * Constructs an empty LRUCache with the specified limit on the number of items in the cache.

+	 * 

+	 * @param limit - the maximum number of items to keep in the cache.

+	 */

+	public LRUCache(int limit) {

+		super(limit, 0.75f, true);

+		fLimit= limit;

+	}

+

+	/**

+	 * Constructs an empty LRUCache with the specified initial capacity and limit on the number of items in the cache.

+	 * 

+	 * @param initialCapacity - initial capacity.

+	 * @param limit - the maximum number of items to keep in the cache.

+	 */

+	public LRUCache(int initialCapacity, int limit) {

+		super(initialCapacity, 0.75f, true);

+		fLimit= limit;

+	}

+	

+	@Override

+	protected boolean removeEldestEntry(Entry<K, V> eldest) {

+		return size() >= fLimit;

+	}

+}
\ No newline at end of file
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/ui/newui/AbstractPage.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/ui/newui/AbstractPage.java
index 61270ae07d4..cf9f9f73299 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/ui/newui/AbstractPage.java
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/ui/newui/AbstractPage.java
@@ -979,8 +979,11 @@ implements
 	}
 
 	protected void cfgChanged(ICConfigurationDescription _cfgd) {
-
 		CConfigurationStatus st = _cfgd.getConfigurationStatus();
+		if (st.getCode() == CConfigurationStatus.TOOLCHAIN_NOT_SUPPORTED) {
+			// Re-check, maybe user got the problem fixed 
+			st = _cfgd.getConfigurationData().getStatus();
+		}
 		if (errPane != null && errMessage != null) {
 			if (st.isOK()) {
 				errPane.setVisible(false);