[apacheGH-322] Converted internal hardwired assumptions to user-contr…

…olled ones

sshd-cli/src/main/java/org/apache/sshd/cli/client/SftpCommandMain.java

@@ -140,7 +140,9 @@ public SftpCommandMain(SftpClient client) {
             ValidateUtils.checkTrue(map.put(name, e) == null, "Multiple commands named '%s'", name);
         }
         commandsMap = Collections.unmodifiableMap(map);
-        cwdLocal = System.getProperty("user.dir");
+
+        Path cwdPath = OsUtils.getCurrentWorkingDirectory();
+        cwdLocal = Objects.toString(cwdPath, null);
     }
 
     @Override

sshd-common/src/main/java/org/apache/sshd/common/util/ExceptionUtils.java

@@ -117,17 +117,22 @@ public static Throwable peelException(Throwable t) {
             if (target != null) {
                 return peelException(target);
             }
-        } else if (t instanceof ReflectionException) {
-            Throwable target = ((ReflectionException) t).getTargetException();
-            if (target != null) {
-                return peelException(target);
-            }
         } else if (t instanceof ExecutionException) {
             return peelException(resolveExceptionCause(t));
-        } else if (t instanceof MBeanException) {
-            Throwable target = ((MBeanException) t).getTargetException();
-            if (target != null) {
-                return peelException(target);
+        }
+
+        // Android does not have these classes
+        if (!OsUtils.isAndroid()) {
+            if (t instanceof ReflectionException) {
+                Throwable target = ((ReflectionException) t).getTargetException();
+                if (target != null) {
+                    return peelException(target);
+                }
+            } else if (t instanceof MBeanException) {
+                Throwable target = ((MBeanException) t).getTargetException();
+                if (target != null) {
+                    return peelException(target);
+                }
             }
         }
 
@@ -155,5 +160,4 @@ public static RuntimeException toRuntimeException(Throwable t, boolean peelThrow
     public static RuntimeException toRuntimeException(Throwable t) {
         return toRuntimeException(t, true);
     }
-
 }

sshd-common/src/main/java/org/apache/sshd/common/util/OsUtils.java

@@ -18,10 +18,15 @@
  */
 package org.apache.sshd.common.util;
 
+import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.util.Arrays;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Predicate;
+import java.util.function.Supplier;
 
 /**
  * Operating system dependent utility methods.
@@ -48,6 +53,22 @@ public final class OsUtils {
      */
     public static final String OS_TYPE_OVERRIDE_PROP = "org.apache.sshd.osType";
 
+    /**
+     * Property that can be used to override the reported value from {@link #isAndroid()}. If not set then
+     * {@link #ANDROID_DETECTION_PROPERTIES} are used to determine its value. Otherwise, it must contain
+     * the string "android" (case-insensitive)
+     *
+     * @see #ANDROID_PROPERTY_VALUE_MATCHER
+     */
+    public static final String ANDROID_MODE_OVERRIDE_PROP = "org.apache.sshd.androidMode";
+
+    /**
+     * Property that can be used to override the reported value from {@link #isDalvikMachine()}. If not set then
+     * {@link #DALVIK_DETECTION_PROPERTIES} are used to determine its value. Otherwise, it must contain the
+     * string "dalvik" (case-insensitive)
+     */
+    public static final String DALVIK_MACHINE_OVERRIDE_PROP = "org.apache.sshd.dalvikMachine";
+
     public static final String WINDOWS_SHELL_COMMAND_NAME = "cmd.exe";
     public static final String LINUX_SHELL_COMMAND_NAME = "/bin/sh";
 
@@ -58,16 +79,101 @@ public final class OsUtils {
     public static final List<String> WINDOWS_COMMAND
             = Collections.unmodifiableList(Collections.singletonList(WINDOWS_SHELL_COMMAND_NAME));
 
+    /**
+     * System properties consulted in order to detect {@link #isAndroid() Android O/S}.
+     *
+     * @see <A HREF="https://developer.android.com/reference/java/lang/System#getProperties()">Android Developer</A>
+     */
+    public static final List<String> ANDROID_DETECTION_PROPERTIES
+            = Collections.unmodifiableList(
+                    Arrays.asList(
+                        "java.vendor",
+                        "java.specification.vendor",
+                        "java.vm.vendor",
+                        "java.vm.specification.vendor"));
+
+    public static final Predicate<String> ANDROID_PROPERTY_VALUE_MATCHER
+            = v -> GenericUtils.trimToEmpty(v).toLowerCase().contains("android");
+
+    /**
+     * System properties consulted in order to detect {@link #isDalvikMachine() Dalvik machine}.
+     *
+     * @see <A HREF="https://developer.android.com/reference/java/lang/System#getProperties()">Android Developer</A>
+     */
+    public static final List<String> DALVIK_DETECTION_PROPERTIES
+            = Collections.unmodifiableList(
+            Arrays.asList(
+                    "java.specification.name",
+                    "java.vm.name",
+                    "java.vm.specification.name"));
+
+    public static final Predicate<String> DALVIK_PROPERTY_VALUE_MATCHER
+            = v -> GenericUtils.trimToEmpty(v).toLowerCase().contains("dalvik");
+
     private static final AtomicReference<String> CURRENT_USER_HOLDER = new AtomicReference<>(null);
     private static final AtomicReference<VersionInfo> JAVA_VERSION_HOLDER = new AtomicReference<>(null);
     private static final AtomicReference<String> OS_TYPE_HOLDER = new AtomicReference<>(null);
 
+    private static final AtomicReference<Boolean> ANDROID_HOLDER = new AtomicReference<>(null);
+    private static final AtomicReference<Boolean> DALVIK_HOLDER = new AtomicReference<>(null);
+
+    private static final AtomicReference<Supplier<? extends Path>> CWD_PROVIDER_HOLDER = new AtomicReference<>();
+
     private OsUtils() {
         throw new UnsupportedOperationException("No instance allowed");
     }
 
     /**
-     * @return true if the host is a UNIX system (and not Windows).
+     * @return {@code true} if currently running on Android. <U>Note:</U> {@link #isUNIX()} is also
+     * probably {@code true} as well, so special care must be taken in code that consults these values
+     * @see #ANDROID_DETECTION_PROPERTIES
+     * @see #ANDROID_MODE_OVERRIDE_PROP
+     * @see #ANDROID_PROPERTY_VALUE_MATCHER
+     */
+    public static boolean isAndroid() {
+        return resolveAndroidSettingFlag(
+            ANDROID_HOLDER, ANDROID_MODE_OVERRIDE_PROP, ANDROID_DETECTION_PROPERTIES, ANDROID_PROPERTY_VALUE_MATCHER);
+    }
+
+    /**
+     * Override the value returned by {@link #isAndroid()} programmatically
+     *
+     * @param value Value to set if {@code null} then value is auto-detected
+     */
+    public static void setAndroid(Boolean value) {
+        synchronized (ANDROID_HOLDER) {
+            ANDROID_HOLDER.set(value);
+        }
+    }
+
+    /**
+     * @return {@code true} if currently running on a Dalvik machine. <U>Note:</U> {@link #isUNIX()}
+     * and/or {@link #isAndroid()} are also probably {@code true} as well, so special care must be taken in
+     * code that consults these values
+     * @see #DALVIK_DETECTION_PROPERTIES
+     * @see #DALVIK_MACHINE_OVERRIDE_PROP
+     * @see #DALVIK_PROPERTY_VALUE_MATCHER
+     */
+    public static boolean isDalvikMachine() {
+        return resolveAndroidSettingFlag(
+            DALVIK_HOLDER, DALVIK_MACHINE_OVERRIDE_PROP, DALVIK_DETECTION_PROPERTIES, DALVIK_PROPERTY_VALUE_MATCHER);
+    }
+
+    /**
+     * Override the value returned by {@link #isDalvikMachine()} programmatically
+     *
+     * @param value Value to set if {@code null} then value is auto-detected
+     */
+    public static void setDalvikMachine(Boolean value) {
+        synchronized (DALVIK_HOLDER) {
+            DALVIK_HOLDER.set(value);
+        }
+    }
+
+    /**
+     * @return true if the host is a UNIX system (and not Windows). <U>Note:</U> this
+     * does <B>not</B> preclude {@link #isAndroid()} or {@link #isDalvikMachine()} from
+     * being {@code true} as well.
      */
     public static boolean isUNIX() {
         return !isWin32() && !isOSX();
@@ -103,6 +209,34 @@ public static void setOS(String os) {
         }
     }
 
+    private static boolean resolveAndroidSettingFlag(
+            AtomicReference<Boolean> flagHolder, String overrideProp,
+            Collection<String> detectionProps, Predicate<? super String> detector) {
+        synchronized (flagHolder) {
+            Boolean value = flagHolder.get();
+            if (value != null) {
+                return value.booleanValue();
+            }
+
+            String propValue = System.getProperty(overrideProp);
+            if (detector.test(propValue)) {
+                flagHolder.set(Boolean.TRUE);
+                return true;
+            }
+
+            for (String p : detectionProps) {
+                if (detector.test(propValue)) {
+                    flagHolder.set(Boolean.TRUE);
+                    return true;
+                }
+            }
+
+            flagHolder.set(Boolean.FALSE);
+        }
+
+        return false;
+    }
+
     /**
      * @return The resolved O/S type string if not already set (lowercase)
      */
@@ -142,14 +276,54 @@ public static List<String> resolveDefaultInteractiveCommandElements(boolean winO
         }
     }
 
+    /**
+     * @return The (C)urrent (W)orking (D)irectory {@link Path} - {@code null} if cannot resolve it. Resolution
+     * occurs as follows:
+     * <UL>
+     *     <LI>
+     *     Consult any currently registered {@link #setCurrentWorkingDirectoryResolver(Supplier) resolver}.
+     *     </LI>
+     *
+     *     <LI>
+     *     If no resolver registered, then &quot;user.dir&quot; system property is consulted.
+     *     </LI>
+     * </UL>
+     * @see #setCurrentWorkingDirectoryResolver(Supplier)
+     */
+    public static Path getCurrentWorkingDirectory() {
+        Supplier<? extends Path> cwdProvider;
+        synchronized (CWD_PROVIDER_HOLDER) {
+            cwdProvider = CWD_PROVIDER_HOLDER.get();
+        }
+
+        if (cwdProvider != null) {
+            return cwdProvider.get();
+        }
+
+        String cwdLocal = System.getProperty("user.dir");
+        return GenericUtils.isBlank(cwdLocal) ? null : Paths.get(cwdLocal);
+    }
+
+    /**
+     * Allows the user to &quot;plug-in&quot; a resolver for the {@link #getCurrentWorkingDirectory()} method
+     *
+     * @param cwdProvider The {@link Supplier} of the (C)urrent (W)orking (D)irectory {@link Path} - if {@code null}
+     *                    then &quot;user.dir&quot; system property is consulted
+     */
+    public static void setCurrentWorkingDirectoryResolver(Supplier<? extends Path> cwdProvider) {
+        synchronized (CWD_PROVIDER_HOLDER) {
+            CWD_PROVIDER_HOLDER.set(cwdProvider);
+        }
+    }
+
     /**
      * Get current user name
      *
      * @return Current user
      * @see    #CURRENT_USER_OVERRIDE_PROP
      */
     public static String getCurrentUser() {
-        String username = null;
+        String username;
         synchronized (CURRENT_USER_HOLDER) {
             username = CURRENT_USER_HOLDER.get();
             if (username != null) { // have we already resolved it ?

sshd-common/src/main/java/org/apache/sshd/common/util/io/PathUtils.java

@@ -24,6 +24,7 @@
 import java.nio.file.Paths;
 import java.util.Comparator;
 import java.util.Objects;
+import java.util.concurrent.atomic.AtomicReference;
 
 import org.apache.sshd.common.util.GenericUtils;
 import org.apache.sshd.common.util.ValidateUtils;
@@ -46,6 +47,8 @@ public final class PathUtils {
     public static final UnaryEquator<Path> EQ_CASE_SENSITIVE_FILENAME
             = (p1, p2) -> BY_CASE_SENSITIVE_FILENAME.compare(p1, p2) == 0;
 
+    private static final AtomicReference<Path> USER_HOME_HOLDER = new AtomicReference<>();
+
     private static final class LazyDefaultUserHomeFolderHolder {
         private static final Path PATH
                 = Paths.get(ValidateUtils.checkNotNullAndNotEmpty(System.getProperty("user.home"), "No user home"))
@@ -118,10 +121,28 @@ public static String normalizePath(String path) {
 
     /**
      * @return The {@link Path} to the currently running user home
+     * @see #setUserHomeFolder(Path)
      */
     @SuppressWarnings("synthetic-access")
     public static Path getUserHomeFolder() {
-        return LazyDefaultUserHomeFolderHolder.PATH;
+        Path path;
+        synchronized (USER_HOME_HOLDER) {
+            path = USER_HOME_HOLDER.get();
+        }
+
+        return (path == null) ? LazyDefaultUserHomeFolderHolder.PATH : path;
+    }
+
+    /**
+     * Set the reported value from {@link #getUserHomeFolder()}
+     *
+     * @param path The {@link Path} to report - if {@code null} then &quot;user.home&quot; system
+     *             property will be used
+     */
+    public static void setUserHomeFolder(Path path) {
+        synchronized (USER_HOME_HOLDER) {
+            USER_HOME_HOLDER.set(path);
+        }
     }
 
     public static StringBuilder appendUserHome(StringBuilder sb) {

sshd-contrib/src/main/java/org/apache/sshd/contrib/common/util/security/androidopenssl/AndroidOpenSSLSecurityProviderRegistrar.java

@@ -21,6 +21,7 @@
 import java.security.Provider;
 import java.security.Security;
 
+import org.apache.sshd.common.util.OsUtils;
 import org.apache.sshd.common.util.security.AbstractSecurityProviderRegistrar;
 
 /**
@@ -42,7 +43,7 @@ public AndroidOpenSSLSecurityProviderRegistrar() {
     public boolean isSupported() {
         // Check that we are running on Android
         // https://developer.android.com/reference/java/lang/System#getProperties()
-        return "The Android Project".equals(System.getProperty("java.specification.vendor"));
+        return OsUtils.isAndroid();
     }
 
     @Override

sshd-scp/src/main/java/org/apache/sshd/scp/common/ScpFileOpener.java

@@ -20,6 +20,7 @@
 package org.apache.sshd.scp.common;
 
 import java.io.File;
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -31,7 +32,6 @@
 import java.nio.file.LinkOption;
 import java.nio.file.OpenOption;
 import java.nio.file.Path;
-import java.nio.file.Paths;
 import java.nio.file.attribute.BasicFileAttributeView;
 import java.nio.file.attribute.BasicFileAttributes;
 import java.nio.file.attribute.FileTime;
@@ -43,6 +43,7 @@
 import org.apache.sshd.common.SshException;
 import org.apache.sshd.common.session.Session;
 import org.apache.sshd.common.util.GenericUtils;
+import org.apache.sshd.common.util.OsUtils;
 import org.apache.sshd.common.util.SelectorUtils;
 import org.apache.sshd.common.util.io.DirectoryScanner;
 import org.apache.sshd.common.util.io.IoUtils;
@@ -132,8 +133,10 @@ default Iterable<Path> getMatchingFilesToSend(Session session, Path basedir, Str
         }
 
         if (basedir == null) {
-            String cwdLocal = System.getProperty("user.dir");
-            Path cwdPath = Paths.get(cwdLocal);
+            Path cwdPath = OsUtils.getCurrentWorkingDirectory();
+            if (cwdPath == null) {
+                throw new FileNotFoundException("No CWD value available");
+            }
             basedir = cwdPath.toAbsolutePath();
         }