BluetoothFactory: Attempt to load native libraries from 'os_and_arch' subdir to CWD and 'java.library.path', supporting multi-platform deployment.

This change resolved initial attempts as discussed in
- commit 70e9b98afce8d9e6f1e7ce5eb477bc8503950cbe
- commit 2d6c05f88c379f9091d291aad90fc03e4ea10b33

+++

In detail, PlatformToolkit's loadLibrary(..), takes a libBaseName,
a library basename without prefix (like 'lib') or suffix like '.so'.

Basic order of library locations

User locations:
  - current working directory + {@link #os_and_arch}
  - iterate through paths within 'java.library.path', adding {@link #os_and_arch} to each
  - current working directory
  - iterate through paths within 'java.library.path'

System locations:
  - optional OSX path
  - iterate through paths within 'sun.boot.library.path'

If the above fails, {@link System#loadLibrary(String)} is called using the plain {@code libBaseName},
exhausting all simple locations and methods.

Example:
  /usr/local/projects/direct_bt/dist-amd64/linux-amd64/libdirect_bt.so (addPath cwd.os_and_arch)
  /usr/local/projects/direct_bt/dist-amd64/lib/linux-amd64/libdirect_bt.so (addPath java-user-libpath.os_and_arch:0)
  /usr/local/projects/direct_bt/dist-amd64/libdirect_bt.so (addPath cwd)
  /usr/local/projects/direct_bt/dist-amd64/lib/libdirect_bt.so (addPath java-user-libpath:0)
  /usr/lib/jvm/java-14-openjdk-amd64/lib/libdirect_bt.so (addPath java-boot-libpath:0)

2 files changed, 338 insertions, 46 deletions

diff --git a/java/org/tinyb/BluetoothFactory.java b/java/org/tinyb/BluetoothFactory.java
index fb1afdca..41694254 100644
--- a/java/org/tinyb/BluetoothFactory.java
+++ b/java/org/tinyb/BluetoothFactory.java
@@ -29,6 +29,8 @@ import java.io.InputStream;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
 import java.net.URL;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
 import java.util.ArrayList;
 import java.util.Enumeration;
 import java.util.Iterator;
@@ -187,50 +189,6 @@ public class BluetoothFactory {
         return null == initializedID;
     }
 
-    private static synchronized boolean loadLibrary(final String basename, final Throwable[] t) {
-        try {
-            System.loadLibrary(basename);
-            System.err.println("Loaded native library with basename <"+basename+">");
-            return true;
-        } catch (final Throwable e) {
-            System.err.println("Failed to load native library <"+basename+">, cause "+e.getMessage());
-            t[0] = e;
-            return false;
-        }
-    }
-    private static synchronized void loadLibrary(final String os_and_arch, final String basename) {
-        boolean done = false;
-        final Throwable t[] = { null };
-        if( null != os_and_arch ) {
-            final String basename2 = basename+"-"+os_and_arch;
-            done = loadLibrary(basename2, t);
-        }
-        if( !done ) {
-            done = loadLibrary(basename, t);
-            if( !done ) {
-                throw new RuntimeException("Couldn't load native library with basename <"+basename+">, os_and_arch <"+os_and_arch+">", t[0]);
-            }
-        }
-    }
-    @SuppressWarnings("unused")
-    private static synchronized void loadLibraries(final ImplementationIdentifier id) {
-        final String os_and_arch;
-        if( false ) {
-            // disable os_and_arch feature for now...
-            final String os_name = System.getProperty("os.name").toLowerCase();
-            final String os_arch = System.getProperty("os.arch").toLowerCase();
-            if( null != os_name && os_name.length() > 0 && null != os_arch && os_arch.length() > 0 ) {
-                os_and_arch = os_name+"-"+os_arch;
-            } else {
-                os_and_arch = null;
-            }
-        } else {
-            os_and_arch = null;
-        }
-        loadLibrary(os_and_arch, id.ImplementationNativeLibraryBasename);
-        loadLibrary(os_and_arch, id.JavaNativeLibraryBasename);
-    }
-
     private static synchronized void initLibrary(final ImplementationIdentifier id) {
         if( null != initializedID ) {
             if( id != initializedID ) {
@@ -240,7 +198,13 @@ public class BluetoothFactory {
         }
 
         try {
-            loadLibraries(id);
+            final Throwable[] t = { null };
+            if( !PlatformToolkit.loadLibrary(id.ImplementationNativeLibraryBasename, BluetoothFactory.class.getClassLoader(), t) ) {
+                throw new RuntimeException("Couldn't load native library with basename <"+id.ImplementationNativeLibraryBasename+">", t[0]);
+            }
+            if( !PlatformToolkit.loadLibrary(id.JavaNativeLibraryBasename, BluetoothFactory.class.getClassLoader(), t) ) {
+                throw new RuntimeException("Couldn't load native library with basename <"+id.JavaNativeLibraryBasename+">", t[0]);
+            }
         } catch (final Throwable e) {
             e.printStackTrace();
             throw e; // fwd exception - end here
@@ -250,7 +214,12 @@ public class BluetoothFactory {
             if( DEBUG ) {
                 System.err.println("BlootoothFactory: Mapping properties to native environment");
             }
-            final Properties props = System.getProperties();
+            final Properties props = AccessController.doPrivileged(new PrivilegedAction<Properties>() {
+                  @Override
+                  public Properties run() {
+                      return System.getProperties();
+                  } });
+
             final Enumeration<?> enums = props.propertyNames();
             while (enums.hasMoreElements()) {
               final String key = (String) enums.nextElement();
diff --git a/java/org/tinyb/PlatformToolkit.java b/java/org/tinyb/PlatformToolkit.java
new file mode 100644
index 00000000..0c89c649
--- /dev/null
+++ b/java/org/tinyb/PlatformToolkit.java
@@ -0,0 +1,323 @@
+/**
+ * Author: Sven Gothel <[email protected]>
+ * Copyright (c) 2020 Gothel Software e.K.
+ * Copyright (c) 2020 ZAFENA AB
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+package org.tinyb;
+
+import java.io.File;
+import java.security.AccessController;
+import java.security.PrivilegedAction;
+import java.util.ArrayList;
+import java.util.Iterator;
+import java.util.List;
+import java.util.StringTokenizer;
+
+
+/**
+ * Miscellaneous platform utilities, allowed to be used within same Java package.
+ */
+final class PlatformToolkit {
+  private static boolean DEBUG = true;
+  private static boolean DEBUG2 = true;
+
+  private enum OSType {
+      UNIX, MACOS, IOS, WINDOWS;
+  }
+
+  /** Lower case system property '{@code os.name}'. */
+  static final String os_name;
+  /** Lower case system property '{@code os.arch}' */
+  static final String os_arch;
+  private static final String user_dir;
+  private static final String java_user_lib_path;
+  private static final String java_boot_lib_path;
+
+  /**
+   * Unique platform denominator composed as '{@link #os_name}' + '-' + '{@link #os_arch}'.
+   */
+  static final String os_and_arch;
+  static final OSType OS_TYPE;
+  private static final boolean isOSX;
+
+  private static final String prefix;
+  private static final String suffix;
+
+  static {
+    {
+        final String[] props =
+          AccessController.doPrivileged(new PrivilegedAction<String[]>() {
+              @Override
+              public String[] run() {
+                final String[] props = new String[5];
+                int i=0;
+                props[i++] = System.getProperty("os.name").toLowerCase(); // 0
+                props[i++] = System.getProperty("os.arch").toLowerCase(); // 1
+                props[i++] = System.getProperty("user.dir"); // 2
+                props[i++] = System.getProperty("java.library.path"); // 3
+                props[i++] = System.getProperty("sun.boot.library.path"); // 4
+                return props;
+              }
+            });
+        int i=0;
+        os_name = props[i++];
+        os_arch = props[i++];
+        user_dir = props[i++];
+        java_user_lib_path = props[i++];
+        java_boot_lib_path = props[i++];
+    }
+
+    if( null != os_name && os_name.length() > 0 && null != os_arch && os_arch.length() > 0 ) {
+        os_and_arch = os_name+"-"+os_arch;
+    } else {
+        os_and_arch = null;
+    }
+
+    if ( os_name.startsWith("mac os x") ||
+         os_name.startsWith("darwin") ) {
+        OS_TYPE = OSType.MACOS;
+        isOSX = true;
+    } else if ( os_name.startsWith("ios") ) {
+        OS_TYPE = OSType.IOS;
+        isOSX = true;
+    } else if ( os_name.startsWith("windows") ) {
+        OS_TYPE = OSType.WINDOWS;
+        isOSX = false;
+    } else {
+        OS_TYPE = OSType.UNIX;
+        isOSX = false;
+    }
+
+    switch (OS_TYPE) {
+      case WINDOWS:
+        prefix = "";
+        suffix = ".dll";
+        break;
+
+      case MACOS:
+      case IOS:
+        prefix = "lib";
+        suffix = ".dylib";
+        break;
+
+      /*
+      case UNIX: */
+      default:
+        prefix = "lib";
+        suffix = ".so";
+        break;
+    }
+  }
+
+  /**
+   * Produces a list of potential full native library pathnames, denoted by its {@code libBaseName}.
+   *
+   * <p>
+   * Basic order of library locations
+   * <pre>
+   * User locations:
+   *   - current working directory + {@link #os_and_arch}
+   *   - iterate through paths within 'java.library.path', adding {@link #os_and_arch} to each
+   *   - current working directory
+   *   - iterate through paths within 'java.library.path'
+   *
+   * System locations:
+   *   - optional OSX path
+   *   - iterate through paths within 'sun.boot.library.path'
+   * </pre>
+   * </p>
+   *
+   * <p>
+   * Example:
+   * <pre>
+     /usr/local/projects/direct_bt/dist-amd64/linux-amd64/libdirect_bt.so (addPath cwd.os_and_arch)
+     /usr/local/projects/direct_bt/dist-amd64/lib/linux-amd64/libdirect_bt.so (addPath java-user-libpath.os_and_arch:0)
+     /usr/local/projects/direct_bt/dist-amd64/libdirect_bt.so (addPath cwd)
+     /usr/local/projects/direct_bt/dist-amd64/lib/libdirect_bt.so (addPath java-user-libpath:0)
+     /usr/lib/jvm/java-14-openjdk-amd64/lib/libdirect_bt.so (addPath java-boot-libpath:0)
+   * </pre>
+   *
+   * @param libBaseName library basename without prefix (like 'lib') or suffix like '.so'.
+   * @param searchSystemPath
+   * @param searchSystemPathFirst
+   * @param loader
+   * @return
+   */
+  private static final List<String> enumerateLibraryPaths(final String libBaseName,
+                                                   final boolean searchSystemPath,
+                                                   final boolean searchSystemPathFirst,
+                                                   final ClassLoader loader) {
+    final List<String> paths = new ArrayList<String>();
+
+    if ( libBaseName == null || libBaseName.length() == 0 ) {
+      return paths;
+    }
+
+    final String libPlatformName = getPlatformName(libBaseName);
+
+    if( searchSystemPath && searchSystemPathFirst ) {
+        // Add probable Mac OS X-specific paths
+        if ( isOSX ) {
+            // Add historical location
+            addPath("osx-1", "/Library/Frameworks/" + libBaseName + ".framework", libPlatformName, paths);
+            // Add current location
+            addPath("osx-2", "/System/Library/Frameworks/" + libBaseName + ".framework", libPlatformName, paths);
+        }
+        addMultiPaths("java-boot-libpath", java_boot_lib_path, libPlatformName, paths);
+    }
+
+    addPath("cwd.os_and_arch", user_dir+File.separator+os_and_arch, libPlatformName, paths);
+    addMultiPaths2("java-user-libpath.os_and_arch", java_user_lib_path, os_and_arch, libPlatformName, paths);
+
+    addPath("cwd", user_dir, libPlatformName, paths);
+    addMultiPaths("java-user-libpath", java_user_lib_path, libPlatformName, paths);
+
+    if( searchSystemPath && !searchSystemPathFirst ) {
+        // Add probable Mac OS X-specific paths
+        if ( isOSX ) {
+            // Add historical location
+            addPath("osx-1", "/Library/Frameworks/" + libBaseName + ".Framework", libPlatformName, paths);
+            // Add current location
+            addPath("osx-2", "/System/Library/Frameworks/" + libBaseName + ".Framework", libPlatformName, paths);
+        }
+        addMultiPaths("java-boot-libpath", java_boot_lib_path, libPlatformName, paths);
+    }
+
+    return paths;
+  }
+
+
+  private static final String getPlatformName(final String libBaseName) {
+      return prefix + libBaseName + suffix;
+  }
+  private static final void addPath(final String msg, final String path, final String platformName, final List<String> paths) {
+      if( null != path && path.length() > 0 ) {
+          final String fullpath = path + File.separator + platformName;
+          if( DEBUG2 ) {
+              System.err.println("  "+fullpath+" (addPath "+msg+")");
+          }
+          paths.add(fullpath);
+      }
+  }
+  private static final void addMultiPaths(final String msg, final String pathList, final String platformName, final List<String> paths) {
+      if( null != pathList && pathList.length() > 0 ) {
+          final StringTokenizer tokenizer = new StringTokenizer(pathList, File.pathSeparator);
+          int i=0;
+          while (tokenizer.hasMoreTokens()) {
+              addPath(msg+":"+i, tokenizer.nextToken(), platformName, paths);
+              i++;
+          }
+      }
+  }
+  private static final void addMultiPaths2(final String msg, final String pathList, final String subDir, final String platformName, final List<String> paths) {
+      if( null != pathList && pathList.length() > 0 && null != subDir && subDir.length() > 0 ) {
+          final StringTokenizer tokenizer = new StringTokenizer(pathList, File.pathSeparator);
+          int i=0;
+          while (tokenizer.hasMoreTokens()) {
+              final String path = tokenizer.nextToken() + File.separator + subDir;
+              addPath(msg+":"+i, path, platformName, paths);
+              i++;
+          }
+      }
+  }
+
+
+  /**
+   * Loads a native library, denoted by its {@code libBaseName}.
+   *
+   * <p>
+   * Basic order of library locations
+   * <pre>
+   * User locations:
+   *   - current working directory + {@link #os_and_arch}
+   *   - iterate through paths within 'java.library.path', adding {@link #os_and_arch} to each
+   *   - current working directory
+   *   - iterate through paths within 'java.library.path'
+   *
+   * System locations:
+   *   - optional OSX path
+   *   - iterate through paths within 'sun.boot.library.path'
+   * </pre>
+   * </p>
+   *
+   * <p>
+   * If the above fails, {@link System#loadLibrary(String)} is called using the plain {@code libBaseName},
+   * exhausting all simple locations and methods.
+   * </p>
+   *
+   * <p>
+   * Example:
+   * <pre>
+     /usr/local/projects/direct_bt/dist-amd64/linux-amd64/libdirect_bt.so (addPath cwd.os_and_arch)
+     /usr/local/projects/direct_bt/dist-amd64/lib/linux-amd64/libdirect_bt.so (addPath java-user-libpath.os_and_arch:0)
+     /usr/local/projects/direct_bt/dist-amd64/libdirect_bt.so (addPath cwd)
+     /usr/local/projects/direct_bt/dist-amd64/lib/libdirect_bt.so (addPath java-user-libpath:0)
+     /usr/lib/jvm/java-14-openjdk-amd64/lib/libdirect_bt.so (addPath java-boot-libpath:0)
+   * </pre>
+   *
+   * @param libBaseName library basename without prefix (like 'lib') or suffix like '.so'.
+   * @param cl
+   * @param t holder to store the last Throwable, if any
+   * @return {@code true} if successful, otherwise {@code false}.
+   */
+  static boolean loadLibrary(final String libBaseName, final ClassLoader cl, final Throwable[] t) {
+      if( DEBUG ) {
+          System.err.println("PlatformToolkit.loadLibrary: libBaseName "+libBaseName+":");
+      }
+      final List<String> possiblePaths = enumerateLibraryPaths(libBaseName, true /* searchSystemPath */, false /* searchSystemPathFirst */, cl);
+      if( DEBUG2 ) {
+          System.err.println();
+      }
+
+      // Iterate down these and see which one if any we can actually find.
+      for (final Iterator<String> iter = possiblePaths.iterator(); iter.hasNext(); ) {
+          final String path = iter.next();
+          try {
+              System.load(path);
+              if( DEBUG ) {
+                  System.err.println("  "+path+" success");
+              }
+              return true;
+          } catch (final Throwable t0) {
+              if( DEBUG ) {
+                  System.err.println("  "+path+" failed: "+t0.getMessage());
+              }
+              t[0] = t0;
+          }
+      }
+
+      // Fall back to loadLibrary
+      try {
+          System.loadLibrary(libBaseName);
+          if( DEBUG ) {
+              System.err.println("  "+libBaseName+" success");
+          }
+          return true;
+      } catch (final Throwable t0) {
+          if( DEBUG ) {
+              System.err.println("  "+libBaseName+" failed: "+t0.getMessage());
+          }
+          t[0] = t0;
+      }
+      return false;
+  }
+}