/*
    * 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:
    *
    *   https://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.CharsetUtil;
  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.MessageDigest;
  import java.security.NoSuchAlgorithmException;
  import java.security.PrivilegedAction;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.EnumSet;
  import java.util.Enumeration;
  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;
      private static final boolean TRY_TO_PATCH_SHADED_ID;
      private static final boolean DETECT_NATIVE_LIBRARY_DUPLICATES;
  
      // Just use a-Z and numbers as valid ID bytes.
      private static final byte[] UNIQUE_ID_BYTES =
              "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".getBytes(CharsetUtil.US_ASCII);
  
      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);
          logger.debug("-Dio.netty.native.deleteLibAfterLoading: {}", DELETE_NATIVE_LIB_AFTER_LOADING);
  
          TRY_TO_PATCH_SHADED_ID = SystemPropertyUtil.getBoolean(
                  "io.netty.native.tryPatchShadedId", true);
          logger.debug("-Dio.netty.native.tryPatchShadedId: {}", TRY_TO_PATCH_SHADED_ID);
  
          DETECT_NATIVE_LIBRARY_DUPLICATES = SystemPropertyUtil.getBoolean(
                  "io.netty.native.detectNativeLibraryDuplicates", true);
          logger.debug("-Dio.netty.native.detectNativeLibraryDuplicates: {}", DETECT_NATIVE_LIBRARY_DUPLICATES);
      }
  
      /**
       * 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);
                 logger.debug("Loaded library with name '{}'", name);
                 return;
             } catch (Throwable t) {
                 suppressed.add(t);
             }
         }
 
         IllegalArgumentException iae =
                 new IllegalArgumentException("Failed to load any of the given libraries: " + Arrays.toString(names));
         ThrowableUtil.addSuppressedAndClear(iae, suppressed);
         throw iae;
     }
 
     /**
      * Calculates the mangled shading prefix added to this class's full name.
      *
      * <p>This method mangles the package name as follows, so we can unmangle it back later:
      * <ul>
      *   <li>{@code _} to {@code _1}</li>
      *   <li>{@code .} to {@code _}</li>
      * </ul>
      *
      * <p>Note that we don't mangle non-ASCII characters here because it's extremely unlikely to have
      * a non-ASCII character in a package name. For more information, see:
      * <ul>
      *   <li><a href="https://docs.oracle.com/javase/8/docs/technotes/guides/jni/spec/design.html">JNI
      *       specification</a></li>
      *   <li>{@code parsePackagePrefix()} in {@code netty_jni_util.c}.</li>
      * </ul>
      *
      * @throws UnsatisfiedLinkError if the shader used something other than a prefix
      */
     private static String calculateMangledPackagePrefix() {
         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())
                           .replace("_", "_1")
                           .replace('.', '_');
     }
 
     /**
      * Load the given library with the specified {@link ClassLoader}
      */
     public static void load(String originalName, ClassLoader loader) {
         String mangledPackagePrefix = calculateMangledPackagePrefix();
         String name = mangledPackagePrefix + 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);
         }
 
         String libname = System.mapLibraryName(name);
         String path = NATIVE_RESOURCE_HOME + libname;
 
         InputStream in = null;
         OutputStream out = null;
         File tmpFile = null;
         URL url = getResource(path, loader);
         try {
             if (url == null) {
                 if (PlatformDependent.isOsx()) {
                     String fileName = path.endsWith(".jnilib") ? NATIVE_RESOURCE_HOME + "lib" + name + ".dynlib" :
                             NATIVE_RESOURCE_HOME + "lib" + name + ".jnilib";
                     url = getResource(fileName, loader);
                     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);
 
             tmpFile = PlatformDependent.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();
 
             if (shouldShadedLibraryIdBePatched(mangledPackagePrefix)) {
                 // Let's try to patch the id and re-sign it. This is a best-effort and might fail if a
                 // SecurityManager is setup or the right executables are not installed :/
                 tryPatchShadedLibraryIdAndSign(tmpFile, originalName);
             }
 
             // 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)) {
                     // Pass "io.netty.native.workdir" as an argument to allow shading tools to see
                     // the string. Since this is printed out to users to tell them what to do next,
                     // we want the value to be correct even when shading.
                     logger.info("{} exists but cannot be executed even when execute permissions set; " +
                                 "check volume for \"noexec\" flag; use -D{}=[path] " +
                                 "to set native working directory separately.",
                                 tmpFile.getPath(), "io.netty.native.workdir");
                 }
             } 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();
             }
         }
     }
 
     private static URL getResource(String path, ClassLoader loader) {
         final Enumeration<URL> urls;
         try {
             if (loader == null) {
                 urls = ClassLoader.getSystemResources(path);
             } else {
                 urls = loader.getResources(path);
             }
         } catch (IOException iox) {
             throw new RuntimeException("An error occurred while getting the resources for " + path, iox);
         }
 
         List<URL> urlsList = Collections.list(urls);
         int size = urlsList.size();
         switch (size) {
             case 0:
                 return null;
             case 1:
                 return urlsList.get(0);
             default:
                 if (DETECT_NATIVE_LIBRARY_DUPLICATES) {
                     try {
                         MessageDigest md = MessageDigest.getInstance("SHA-256");
                         // We found more than 1 resource with the same name. Let's check if the content of the file is
                         // the same as in this case it will not have any bad effect.
                         URL url = urlsList.get(0);
                         byte[] digest = digest(md, url);
                         boolean allSame = true;
                         if (digest != null) {
                             for (int i = 1; i < size; i++) {
                                 byte[] digest2 = digest(md, urlsList.get(i));
                                 if (digest2 == null || !Arrays.equals(digest, digest2)) {
                                     allSame = false;
                                     break;
                                 }
                             }
                         } else {
                             allSame = false;
                         }
                         if (allSame) {
                             return url;
                         }
                     } catch (NoSuchAlgorithmException e) {
                         logger.debug("Don't support SHA-256, can't check if resources have same content.", e);
                     }
 
                     throw new IllegalStateException(
                             "Multiple resources found for '" + path + "' with different content: " + urlsList);
                 } else {
                     logger.warn("Multiple resources found for '" + path + "' with different content: " +
                             urlsList + ". Please fix your dependency graph.");
                     return urlsList.get(0);
                 }
         }
     }
 
     private static byte[] digest(MessageDigest digest, URL url) {
         InputStream in = null;
         try {
             in = url.openStream();
             byte[] bytes = new byte[8192];
             int i;
             while ((i = in.read(bytes)) != -1) {
                 digest.update(bytes, 0, i);
             }
             return digest.digest();
         } catch (IOException e) {
             logger.debug("Can't read resource.", e);
             return null;
         } finally {
             closeQuietly(in);
         }
     }
 
     static void tryPatchShadedLibraryIdAndSign(File libraryFile, String originalName) {
         String newId = new String(generateUniqueId(originalName.length()), CharsetUtil.UTF_8);
         if (!tryExec("install_name_tool -id " + newId + " " + libraryFile.getAbsolutePath())) {
             return;
         }
 
         tryExec("codesign -s - " + libraryFile.getAbsolutePath());
     }
 
     private static boolean tryExec(String cmd) {
         try {
             int exitValue = Runtime.getRuntime().exec(cmd).waitFor();
             if (exitValue != 0) {
                 logger.debug("Execution of '{}' failed: {}", cmd, exitValue);
                 return false;
             }
             logger.debug("Execution of '{}' succeed: {}", cmd, exitValue);
             return true;
         } catch (InterruptedException e) {
             Thread.currentThread().interrupt();
         } catch (IOException e) {
             logger.info("Execution of '{}' failed.", cmd, e);
         } catch (SecurityException e) {
             logger.error("Execution of '{}' failed.", cmd, e);
         }
         return false;
     }
 
     private static boolean shouldShadedLibraryIdBePatched(String packagePrefix) {
         return TRY_TO_PATCH_SHADED_ID && PlatformDependent.isOsx() && !packagePrefix.isEmpty();
     }
 
     private static byte[] generateUniqueId(int length) {
         byte[] idBytes = new byte[length];
         for (int i = 0; i < idBytes.length; i++) {
             // We should only use bytes as replacement that are in our UNIQUE_ID_BYTES array.
             idBytes[i] = UNIQUE_ID_BYTES[PlatformDependent.threadLocalRandom()
                     .nextInt(UNIQUE_ID_BYTES.length)];
         }
         return idBytes;
     }
 
     /**
      * 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 belongs 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;
             } catch (Exception e) {
                 suppressed = e;
             }
             NativeLibraryUtil.loadLibrary(name, absolute);  // Fallback to local helper class.
             logger.debug("Successfully loaded the library {}", name);
         } catch (NoSuchMethodError nsme) {
             if (suppressed != null) {
                 ThrowableUtil.addSuppressed(nsme, suppressed);
             }
             rethrowWithMoreDetailsIfPossible(name, nsme);
         } catch (UnsatisfiedLinkError ule) {
             if (suppressed != null) {
                 ThrowableUtil.addSuppressed(ule, suppressed);
             }
             throw ule;
         }
     }
 
     @SuppressJava6Requirement(reason = "Guarded by version check")
     private static void rethrowWithMoreDetailsIfPossible(String name, NoSuchMethodError error) {
         if (PlatformDependent.javaVersion() >= 7) {
             throw new LinkageError(
                     "Possible multiple incompatible native libraries on the classpath for '" + name + "'?", error);
         }
         throw error;
     }
 
     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 {
 
         @SuppressJava6Requirement(reason = "Usage guarded by java version check")
         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
         }
     }
 }