[226574][api] Add ISubSystemConfiguration#supportsEncoding()

rse/plugins/org.eclipse.rse.core/src/org/eclipse/rse/core/IRSESystemType.java

@@ -16,6 +16,7 @@
  * Martin Oberhuber (Wind River) - [186640] Add IRSESystemType.testProperty()
  * Martin Oberhuber (Wind River) - [218655][api] Provide SystemType enablement info in non-UI
  * Martin Oberhuber (Wind River) - [cleanup] Add API "since" Javadoc tags
+ * Martin Oberhuber (Wind River) - [226574][api] Add ISubSystemConfiguration#supportsEncoding()
  ********************************************************************************/
 
 package org.eclipse.rse.core;
@@ -23,6 +24,7 @@ package org.eclipse.rse.core;
 import org.eclipse.core.runtime.IAdaptable;
 import org.eclipse.rse.core.model.IHost;
 import org.eclipse.rse.core.model.ISystemProfile;
+import org.eclipse.rse.core.subsystems.ISubSystemConfiguration;
 import org.eclipse.rse.internal.core.model.SystemHostPool;
 import org.osgi.framework.Bundle;
 
@@ -197,6 +199,26 @@ public interface IRSESystemType extends IAdaptable {
 	 */
 	public static final String PROPERTY_IS_CASE_SENSITIVE = "isCaseSensitive"; //$NON-NLS-1$
 
+	/**
+	 * System type Property Key (value: "supportsEncoding") indicating whether a
+	 * given system type supports the user specifying an encoding to use for
+	 * translating binary data to Java Unicode Strings when working on
+	 * subsystems.
+	 *
+	 * It is up to the subsystems registered against a given system type whether
+	 * they observe the system type's setting or not; the default
+	 * implementations do observe it. Given that all subsystem configurations
+	 * registered against a given system type do not support encodings, the
+	 * corresponding RSE controls for allowing the user to change encodings will
+	 * be disabled.
+	 *
+	 * Expected default value of this Property is "true" if not set.
+	 *
+	 * @see ISubSystemConfiguration#supportsEncoding(IHost)
+	 * @since org.eclipse.rse.core 3.0
+	 */
+	public static final String PROPERTY_SUPPORTS_ENCODING = "supportsEncoding"; //$NON-NLS-1$
+
 	/**
 	 * Returns the id of the system type.
 	 * @return the id of the system type

rse/plugins/org.eclipse.rse.core/src/org/eclipse/rse/core/subsystems/ISubSystemConfiguration.java

@@ -20,6 +20,7 @@
  * Xuan Chen (IBM) - [223126] [api][breaking] Remove API related to User Actions in RSE Core/UI
  * Martin Oberhuber (Wind River) - [cleanup] Add API "since" Javadoc tags
  * David Dykstal (IBM) - [168976][api] move ISystemNewConnectionWizardPage from core to UI
+ * Martin Oberhuber (Wind River) - [226574][api] Add ISubSystemConfiguration#supportsEncoding()
  ********************************************************************************/
 
 package org.eclipse.rse.core.subsystems;
@@ -65,6 +66,41 @@ public interface ISubSystemConfiguration extends ISystemFilterPoolManagerProvide
 	// ---------------------------------
 	// CRITICAL METHODS...
 	// ---------------------------------
+
+	/**
+	 * Test whether subsystems managed by this configuration support custom
+	 * encodings.
+	 * 
+	 * Encodings specify the way how binary data on the remote system is
+	 * translated into Java Unicode Strings. RSE provides some means for the
+	 * User to specify a particular encoding to use; typically, all subsystems
+	 * that do support custom encodings specified should use the same encoding
+	 * such that they can interoperate. Therefore, encodings are usually
+	 * obtained from {@link IHost#getDefaultEncoding(boolean)}.
+	 * 
+	 * It's possible, however, that a particular subsystem "knows" that its
+	 * resources are always encoded in a particular way, and there is no
+	 * possibility to ever change that. The Subsystem Configuration would return
+	 * <code>false</code> here in this case. Another possibility is that
+	 * encodings for a particular subsystem can be changed, but in a way that's
+	 * different than what RSE usually does. The default case, however, should
+	 * be that subsystems fall back to the setting specified by the host or its
+	 * underlying system type such that existing subsystem configurations can be
+	 * re-used in an environment where the encoding to use is pre-defined by the
+	 * system type or host connection.
+	 * 
+	 * If no subsystem registered against a given host supports encodings, the
+	 * corresponding UI controls on the IHost level are disabled in order to
+	 * avoid confusion to the user.
+	 * 
+	 * @return <code>true<code> if the RSE mechanisms for specifying custom
+	 *     encodings are observed and supported by the subsystems managed
+	 *     by this configuration for the given host.
+	 * @see IRSESystemType#PROPERTY_SUPPORTS_ENCODING
+	 * @since org.eclipse.rse.core 3.0
+	 */
+	public boolean supportsEncoding(IHost host);
+
 	/**
 	 * Return true if the subsystem supports more than one filter string
 	 * <p>RETURNS true BY DEFAULT

rse/plugins/org.eclipse.rse.files.ui/src/org/eclipse/rse/internal/files/ui/propertypages/SystemFilePropertyPage.java

@@ -24,6 +24,7 @@
  * David McKnight   (IBM)        - [209703] apply encoding and updating remote file when apply on property page
  * David McKnight   (IBM)        - [216252] [api][nls] Resource Strings specific to subsystems should be moved from rse.ui into files.ui / shells.ui / processes.ui where possible
  * David McKnight   (IBM)        - [220547] [api][breaking] SimpleSystemMessage needs to specify a message id and some messages should be shared
+ * Martin Oberhuber (Wind River) - [226574][api] Add ISubSystemConfiguration#supportsEncoding()
  *******************************************************************************/
 
 package org.eclipse.rse.internal.files.ui.propertypages;
@@ -41,6 +42,7 @@ import org.eclipse.osgi.util.NLS;
 import org.eclipse.rse.core.RSECorePlugin;
 import org.eclipse.rse.core.events.ISystemResourceChangeEvents;
 import org.eclipse.rse.core.events.SystemResourceChangeEvent;
+import org.eclipse.rse.core.model.IHost;
 import org.eclipse.rse.core.model.ISystemRegistry;
 import org.eclipse.rse.files.ui.resources.SystemEditableRemoteFile;
 import org.eclipse.rse.internal.files.ui.Activator;
@@ -203,8 +205,9 @@ public class SystemFilePropertyPage extends SystemBasePropertyPage
 
 		// check if an encodings field should be added. Add only if the subsystem
 		// indicates that it supports encodings
-		if (file.getParentRemoteFileSubSystem().supportsEncoding()) {
+		IRemoteFileSubSystem subSys = file.getParentRemoteFileSubSystem();
-			
+		IHost host = subSys.getHost();
+		if (subSys.getSubSystemConfiguration().supportsEncoding(host)) {
 			SystemWidgetHelpers.createLabel(composite_prompts, "", 2); //$NON-NLS-1$
 
 			// encoding field

rse/plugins/org.eclipse.rse.ui/subsystems/org/eclipse/rse/core/subsystems/SubSystemConfiguration.java

@@ -34,6 +34,7 @@
  * Xuan Chen        (IBM)        - [223126] [api][breaking] Remove API related to User Actions in RSE Core/UI
  * David McKnight   (IBM)        - [225506] [api][breaking] RSE UI leaks non-API types
  * David Dykstal (IBM) - [168976][api] move ISystemNewConnectionWizardPage from core to UI
+ * Martin Oberhuber (Wind River) - [226574][api] Add ISubSystemConfiguration#supportsEncoding()
  ********************************************************************************/
 
 package org.eclipse.rse.core.subsystems;
@@ -188,6 +189,24 @@ public abstract class SubSystemConfiguration  implements ISubSystemConfiguration
 	// CRITICAL METHODS...
 	// ---------------------------------
 
+	/**
+	 * Test whether this subsystem configuration supports custom encodings. We
+	 * fall back to the setting provided by the host, or its underlying system
+	 * type by default.
+	 *
+	 * @see ISubSystemConfiguration#supportsEncoding(IHost)
+	 * @since org.eclipse.rse.core 3.0
+	 */
+	public boolean supportsEncoding(IHost host) {
+		// support encodings by default
+		boolean rv = true;
+		if (host.getSystemType().testProperty(IRSESystemType.PROPERTY_SUPPORTS_ENCODING, false)) {
+			// switched off on system type level
+			rv = false;
+		}
+		return rv;
+	}
+
 	/**
 	 * Return true if instance of this subsystem configuration's subsystems support connect and disconnect actions.
 	 * <b>By default, returns true</b>.