/*
    * Copyright 2014 The Netty Project
    *
    * The Netty Project licenses this file to you under the Apache License,
    * version 2.0 (the "License"); you may not use this file except in compliance
    * with the License. You may obtain a copy of the License at:
    *
    *   http://www.apache.org/licenses/LICENSE-2.0
    *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
   * License for the specific language governing permissions and limitations
   * under the License.
   */
  package io.netty.util.internal;
  
  import io.netty.util.internal.logging.InternalLogger;
  import io.netty.util.internal.logging.InternalLoggerFactory;
  
  import java.io.ByteArrayOutputStream;
  import java.io.Closeable;
  import java.io.File;
  import java.io.FileNotFoundException;
  import java.io.FileOutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.lang.reflect.Method;
  import java.net.URL;
  import java.security.AccessController;
  import java.security.PrivilegedAction;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.EnumSet;
  import java.util.List;
  import java.util.Set;
  
  /**
   * Helper class to load JNI resources.
   *
   */
  public final class NativeLibraryLoader {
  
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(NativeLibraryLoader.class);
  
      private static final String NATIVE_RESOURCE_HOME = "META-INF/native/";
      private static final File WORKDIR;
      private static final boolean DELETE_NATIVE_LIB_AFTER_LOADING;
  
      static {
          String workdir = SystemPropertyUtil.get("io.netty.native.workdir");
          if (workdir != null) {
              File f = new File(workdir);
              f.mkdirs();
  
              try {
                  f = f.getAbsoluteFile();
              } catch (Exception ignored) {
                  // Good to have an absolute path, but it's OK.
              }
  
              WORKDIR = f;
              logger.debug("-Dio.netty.native.workdir: " + WORKDIR);
          } else {
              WORKDIR = PlatformDependent.tmpdir();
              logger.debug("-Dio.netty.native.workdir: " + WORKDIR + " (io.netty.tmpdir)");
          }
  
          DELETE_NATIVE_LIB_AFTER_LOADING = SystemPropertyUtil.getBoolean(
                  "io.netty.native.deleteLibAfterLoading", true);
      }
  
      /**
       * Loads the first available library in the collection with the specified
       * {@link ClassLoader}.
       *
       * @throws IllegalArgumentException
       *         if none of the given libraries load successfully.
       */
      public static void loadFirstAvailable(ClassLoader loader, String... names) {
          List<Throwable> suppressed = new ArrayList<Throwable>();
          for (String name : names) {
              try {
                  load(name, loader);
                  return;
              } catch (Throwable t) {
                  suppressed.add(t);
                  logger.debug("Unable to load the library '{}', trying next name...", name, t);
              }
          }
          IllegalArgumentException iae =
                  new IllegalArgumentException("Failed to load any of the given libraries: " + Arrays.toString(names));
          ThrowableUtil.addSuppressedAndClear(iae, suppressed);
          throw iae;
      }
  
      /**
       * The shading prefix added to this class's full name.
      *
      * @throws UnsatisfiedLinkError if the shader used something other than a prefix
      */
     private static String calculatePackagePrefix() {
         String maybeShaded = NativeLibraryLoader.class.getName();
         // Use ! instead of . to avoid shading utilities from modifying the string
         String expected = "io!netty!util!internal!NativeLibraryLoader".replace('!', '.');
         if (!maybeShaded.endsWith(expected)) {
             throw new UnsatisfiedLinkError(String.format(
                     "Could not find prefix added to %s to get %s. When shading, only adding a "
                     + "package prefix is supported", expected, maybeShaded));
         }
         return maybeShaded.substring(0, maybeShaded.length() - expected.length());
     }
 
     /**
      * Load the given library with the specified {@link ClassLoader}
      */
     public static void load(String originalName, ClassLoader loader) {
         // Adjust expected name to support shading of native libraries.
         String name = calculatePackagePrefix().replace('.', '_') + originalName;
         List<Throwable> suppressed = new ArrayList<Throwable>();
         try {
             // first try to load from java.library.path
             loadLibrary(loader, name, false);
             return;
         } catch (Throwable ex) {
             suppressed.add(ex);
             logger.debug(
                     "{} cannot be loaded from java.libary.path, "
                     + "now trying export to -Dio.netty.native.workdir: {}", name, WORKDIR, ex);
         }
 
         String libname = System.mapLibraryName(name);
         String path = NATIVE_RESOURCE_HOME + libname;
 
         InputStream in = null;
         OutputStream out = null;
         File tmpFile = null;
         URL url;
         if (loader == null) {
             url = ClassLoader.getSystemResource(path);
         } else {
             url = loader.getResource(path);
         }
         try {
             if (url == null) {
                 if (PlatformDependent.isOsx()) {
                     String fileName = path.endsWith(".jnilib") ? NATIVE_RESOURCE_HOME + "lib" + name + ".dynlib" :
                             NATIVE_RESOURCE_HOME + "lib" + name + ".jnilib";
                     if (loader == null) {
                         url = ClassLoader.getSystemResource(fileName);
                     } else {
                         url = loader.getResource(fileName);
                     }
                     if (url == null) {
                         FileNotFoundException fnf = new FileNotFoundException(fileName);
                         ThrowableUtil.addSuppressedAndClear(fnf, suppressed);
                         throw fnf;
                     }
                 } else {
                     FileNotFoundException fnf = new FileNotFoundException(path);
                     ThrowableUtil.addSuppressedAndClear(fnf, suppressed);
                     throw fnf;
                 }
             }
 
             int index = libname.lastIndexOf('.');
             String prefix = libname.substring(0, index);
             String suffix = libname.substring(index, libname.length());
 
             tmpFile = File.createTempFile(prefix, suffix, WORKDIR);
             in = url.openStream();
             out = new FileOutputStream(tmpFile);
 
             byte[] buffer = new byte[8192];
             int length;
             while ((length = in.read(buffer)) > 0) {
                 out.write(buffer, 0, length);
             }
             out.flush();
 
             // Close the output stream before loading the unpacked library,
             // because otherwise Windows will refuse to load it when it's in use by other process.
             closeQuietly(out);
             out = null;
 
             loadLibrary(loader, tmpFile.getPath(), true);
         } catch (UnsatisfiedLinkError e) {
             try {
                 if (tmpFile != null && tmpFile.isFile() && tmpFile.canRead() &&
                     !NoexecVolumeDetector.canExecuteExecutable(tmpFile)) {
                     logger.info("{} exists but cannot be executed even when execute permissions set; " +
                                 "check volume for \"noexec\" flag; use -Dio.netty.native.workdir=[path] " +
                                 "to set native working directory separately.",
                                 tmpFile.getPath());
                 }
             } catch (Throwable t) {
                 suppressed.add(t);
                 logger.debug("Error checking if {} is on a file store mounted with noexec", tmpFile, t);
             }
             // Re-throw to fail the load
             ThrowableUtil.addSuppressedAndClear(e, suppressed);
             throw e;
         } catch (Exception e) {
             UnsatisfiedLinkError ule = new UnsatisfiedLinkError("could not load a native library: " + name);
             ule.initCause(e);
             ThrowableUtil.addSuppressedAndClear(ule, suppressed);
             throw ule;
         } finally {
             closeQuietly(in);
             closeQuietly(out);
             // After we load the library it is safe to delete the file.
             // We delete the file immediately to free up resources as soon as possible,
             // and if this fails fallback to deleting on JVM exit.
             if (tmpFile != null && (!DELETE_NATIVE_LIB_AFTER_LOADING || !tmpFile.delete())) {
                 tmpFile.deleteOnExit();
             }
         }
     }
 
     /**
      * Loading the native library into the specified {@link ClassLoader}.
      * @param loader - The {@link ClassLoader} where the native library will be loaded into
      * @param name - The native library path or name
      * @param absolute - Whether the native library will be loaded by path or by name
      */
     private static void loadLibrary(final ClassLoader loader, final String name, final boolean absolute) {
         Throwable suppressed = null;
         try {
             try {
                 // Make sure the helper is belong to the target ClassLoader.
                 final Class<?> newHelper = tryToLoadClass(loader, NativeLibraryUtil.class);
                 loadLibraryByHelper(newHelper, name, absolute);
                 logger.debug("Successfully loaded the library {}", name);
                 return;
             } catch (UnsatisfiedLinkError e) { // Should by pass the UnsatisfiedLinkError here!
                 suppressed = e;
                 logger.debug("Unable to load the library '{}', trying other loading mechanism.", name, e);
             } catch (Exception e) {
                 suppressed = e;
                 logger.debug("Unable to load the library '{}', trying other loading mechanism.", name, e);
             }
             NativeLibraryUtil.loadLibrary(name, absolute);  // Fallback to local helper class.
             logger.debug("Successfully loaded the library {}", name);
         } catch (UnsatisfiedLinkError ule) {
             if (suppressed != null) {
                 ThrowableUtil.addSuppressed(ule, suppressed);
             }
             throw ule;
         }
     }
 
     private static void loadLibraryByHelper(final Class<?> helper, final String name, final boolean absolute)
             throws UnsatisfiedLinkError {
         Object ret = AccessController.doPrivileged(new PrivilegedAction<Object>() {
             @Override
             public Object run() {
                 try {
                     // Invoke the helper to load the native library, if succeed, then the native
                     // library belong to the specified ClassLoader.
                     Method method = helper.getMethod("loadLibrary", String.class, boolean.class);
                     method.setAccessible(true);
                     return method.invoke(null, name, absolute);
                 } catch (Exception e) {
                     return e;
                 }
             }
         });
         if (ret instanceof Throwable) {
             Throwable t = (Throwable) ret;
             assert !(t instanceof UnsatisfiedLinkError) : t + " should be a wrapper throwable";
             Throwable cause = t.getCause();
             if (cause instanceof UnsatisfiedLinkError) {
                 throw (UnsatisfiedLinkError) cause;
             }
             UnsatisfiedLinkError ule = new UnsatisfiedLinkError(t.getMessage());
             ule.initCause(t);
             throw ule;
         }
     }
 
     /**
      * Try to load the helper {@link Class} into specified {@link ClassLoader}.
      * @param loader - The {@link ClassLoader} where to load the helper {@link Class}
      * @param helper - The helper {@link Class}
      * @return A new helper Class defined in the specified ClassLoader.
      * @throws ClassNotFoundException Helper class not found or loading failed
      */
     private static Class<?> tryToLoadClass(final ClassLoader loader, final Class<?> helper)
             throws ClassNotFoundException {
         try {
             return Class.forName(helper.getName(), false, loader);
         } catch (ClassNotFoundException e1) {
             if (loader == null) {
                 // cannot defineClass inside bootstrap class loader
                 throw e1;
             }
             try {
                 // The helper class is NOT found in target ClassLoader, we have to define the helper class.
                 final byte[] classBinary = classToByteArray(helper);
                 return AccessController.doPrivileged(new PrivilegedAction<Class<?>>() {
                     @Override
                     public Class<?> run() {
                         try {
                             // Define the helper class in the target ClassLoader,
                             //  then we can call the helper to load the native library.
                             Method defineClass = ClassLoader.class.getDeclaredMethod("defineClass", String.class,
                                     byte[].class, int.class, int.class);
                             defineClass.setAccessible(true);
                             return (Class<?>) defineClass.invoke(loader, helper.getName(), classBinary, 0,
                                     classBinary.length);
                         } catch (Exception e) {
                             throw new IllegalStateException("Define class failed!", e);
                         }
                     }
                 });
             } catch (ClassNotFoundException e2) {
                 ThrowableUtil.addSuppressed(e2, e1);
                 throw e2;
             } catch (RuntimeException e2) {
                 ThrowableUtil.addSuppressed(e2, e1);
                 throw e2;
             } catch (Error e2) {
                 ThrowableUtil.addSuppressed(e2, e1);
                 throw e2;
             }
         }
     }
 
     /**
      * Load the helper {@link Class} as a byte array, to be redefined in specified {@link ClassLoader}.
      * @param clazz - The helper {@link Class} provided by this bundle
      * @return The binary content of helper {@link Class}.
      * @throws ClassNotFoundException Helper class not found or loading failed
      */
     private static byte[] classToByteArray(Class<?> clazz) throws ClassNotFoundException {
         String fileName = clazz.getName();
         int lastDot = fileName.lastIndexOf('.');
         if (lastDot > 0) {
             fileName = fileName.substring(lastDot + 1);
         }
         URL classUrl = clazz.getResource(fileName + ".class");
         if (classUrl == null) {
             throw new ClassNotFoundException(clazz.getName());
         }
         byte[] buf = new byte[1024];
         ByteArrayOutputStream out = new ByteArrayOutputStream(4096);
         InputStream in = null;
         try {
             in = classUrl.openStream();
             for (int r; (r = in.read(buf)) != -1;) {
                 out.write(buf, 0, r);
             }
             return out.toByteArray();
         } catch (IOException ex) {
             throw new ClassNotFoundException(clazz.getName(), ex);
         } finally {
             closeQuietly(in);
             closeQuietly(out);
         }
     }
 
     private static void closeQuietly(Closeable c) {
         if (c != null) {
             try {
                 c.close();
             } catch (IOException ignore) {
                 // ignore
             }
         }
     }
 
     private NativeLibraryLoader() {
         // Utility
     }
 
     private static final class NoexecVolumeDetector {
 
         private static boolean canExecuteExecutable(File file) throws IOException {
             if (PlatformDependent.javaVersion() < 7) {
                 // Pre-JDK7, the Java API did not directly support POSIX permissions; instead of implementing a custom
                 // work-around, assume true, which disables the check.
                 return true;
             }
 
             // If we can already execute, there is nothing to do.
             if (file.canExecute()) {
                 return true;
             }
 
             // On volumes, with noexec set, even files with the executable POSIX permissions will fail to execute.
             // The File#canExecute() method honors this behavior, probaby via parsing the noexec flag when initializing
             // the UnixFileStore, though the flag is not exposed via a public API.  To find out if library is being
             // loaded off a volume with noexec, confirm or add executalbe permissions, then check File#canExecute().
 
             // Note: We use FQCN to not break when netty is used in java6
             Set<java.nio.file.attribute.PosixFilePermission> existingFilePermissions =
                     java.nio.file.Files.getPosixFilePermissions(file.toPath());
             Set<java.nio.file.attribute.PosixFilePermission> executePermissions =
                     EnumSet.of(java.nio.file.attribute.PosixFilePermission.OWNER_EXECUTE,
                             java.nio.file.attribute.PosixFilePermission.GROUP_EXECUTE,
                             java.nio.file.attribute.PosixFilePermission.OTHERS_EXECUTE);
             if (existingFilePermissions.containsAll(executePermissions)) {
                 return false;
             }
 
             Set<java.nio.file.attribute.PosixFilePermission> newPermissions = EnumSet.copyOf(existingFilePermissions);
             newPermissions.addAll(executePermissions);
             java.nio.file.Files.setPosixFilePermissions(file.toPath(), newPermissions);
             return file.canExecute();
         }
 
         private NoexecVolumeDetector() {
             // Utility
         }
     }
 }