/*

 * Copyright (c) 2019, Red Hat, Inc.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.tools.jlink.internal.plugins;

import java.io.IOException;

import java.lang.ProcessBuilder.Redirect;

import java.nio.file.FileVisitResult;

import java.nio.file.Files;

import java.nio.file.InvalidPathException;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.SimpleFileVisitor;

import java.nio.file.attribute.BasicFileAttributes;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.HashMap;

import java.util.List;

import java.util.Locale;

import java.util.Map;

import java.util.MissingResourceException;

import java.util.Objects;

import java.util.Optional;

import java.util.ResourceBundle;

import jdk.tools.jlink.plugin.Plugin;

import jdk.tools.jlink.plugin.PluginException;

import jdk.tools.jlink.plugin.ResourcePool;

import jdk.tools.jlink.plugin.ResourcePoolBuilder;

import jdk.tools.jlink.plugin.ResourcePoolEntry;

/**

 * Platform specific jlink plugin for stripping debug symbols from native

 * libraries and binaries.

 *

 */

public final class StripNativeDebugSymbolsPlugin implements Plugin {

    public static final String NAME = "strip-native-debug-symbols";

    private static final boolean DEBUG = Boolean.getBoolean("jlink.debug");

    private static final String DEFAULT_STRIP_CMD = "objcopy";

    private static final String STRIP_CMD_ARG = DEFAULT_STRIP_CMD;

    private static final String KEEP_DEBUG_INFO_ARG = "keep-debuginfo-files";

    private static final String EXCLUDE_DEBUG_INFO_ARG = "exclude-debuginfo-files";

    private static final String DEFAULT_DEBUG_EXT = "debuginfo";

    private static final String STRIP_DEBUG_SYMS_OPT = "-g";

    private static final String ONLY_KEEP_DEBUG_SYMS_OPT = "--only-keep-debug";

    private static final String ADD_DEBUG_LINK_OPT = "--add-gnu-debuglink";

    private static final ResourceBundle resourceBundle;

    private static final String SHARED_LIBS_EXT = ".so"; // for Linux/Unix

    static {

        Locale locale = Locale.getDefault();

        try {

            resourceBundle = ResourceBundle.getBundle("jdk.tools.jlink."

                    + "resources.strip_native_debug_symbols_plugin", locale);

        } catch (MissingResourceException e) {

            throw new InternalError("Cannot find jlink plugin resource bundle (" +

                        NAME + ") for locale " + locale);

        }

    }

    private final ObjCopyCmdBuilder cmdBuilder;

    private boolean includeDebugSymbols;

    private String stripBin;

    private String debuginfoExt;

    public StripNativeDebugSymbolsPlugin() {

        this(new DefaultObjCopyCmdBuilder());

    }

    public StripNativeDebugSymbolsPlugin(ObjCopyCmdBuilder cmdBuilder) {

        this.cmdBuilder = cmdBuilder;

    }

    @Override

    public String getName() {

        return NAME;

    }

    @Override

    public ResourcePool transform(ResourcePool in, ResourcePoolBuilder out) {

        StrippedDebugInfoBinaryBuilder builder = new StrippedDebugInfoBinaryBuilder(

                                                        includeDebugSymbols,

                                                        debuginfoExt,

                                                        cmdBuilder,

                                                        stripBin);

        in.transformAndCopy((resource) -> {

            ResourcePoolEntry res = resource;

            if ((resource.type() == ResourcePoolEntry.Type.NATIVE_LIB &&

                 resource.path().endsWith(SHARED_LIBS_EXT)) ||

                resource.type() == ResourcePoolEntry.Type.NATIVE_CMD) {

                Optional<StrippedDebugInfoBinary> strippedBin = builder.build(resource);

                if (strippedBin.isPresent()) {

                    StrippedDebugInfoBinary sb = strippedBin.get();

                    res = sb.strippedBinary();

                    if (includeDebugSymbols) {

                        Optional<ResourcePoolEntry> debugInfo = sb.debugSymbols();

                        if (debugInfo.isEmpty()) {

                            String key = NAME + ".error.debugfile";

                            logError(resource, key);

                        } else {

                            out.add(debugInfo.get());

                        }

                    }

                } else {

                    String key = NAME + ".error.file";

                    logError(resource, key);

                }

            }

            return res;

        }, out);

        return out.build();

    }

    private void logError(ResourcePoolEntry resource, String msgKey) {

        String msg = PluginsResourceBundle.getMessage(resourceBundle,

                                                      msgKey,

                                                      NAME,

                                                      resource.path());

        System.err.println(msg);

    }

    @Override

    public Category getType() {

        return Category.TRANSFORMER;

    }

    @Override

    public String getDescription() {

        String key = NAME + ".description";

        return PluginsResourceBundle.getMessage(resourceBundle, key);

    }

    @Override

    public boolean hasArguments() {

        return true;

    }

    @Override

    public String getArgumentsDescription() {

        String key = NAME + ".argument";

        return PluginsResourceBundle.getMessage(resourceBundle, key);

    }

    @Override

    public void configure(Map<String, String> config) {

        doConfigure(true, config);

    }

    // For testing so that validation can be turned off

    public void doConfigure(boolean withChecks, Map<String, String> orig) {

        Map<String, String> config = new HashMap<>(orig);

        String arg = config.remove(NAME);

        stripBin = DEFAULT_STRIP_CMD;

        debuginfoExt = DEFAULT_DEBUG_EXT;

        // argument must never be null as it requires at least one

        // argument, since hasArguments() == true. This might change once

        // 8218761 is implemented.

        if (arg == null) {

            throw new InternalError();

        }

        boolean hasOmitDebugInfo = false;

        boolean hasKeepDebugInfo = false;

        if (KEEP_DEBUG_INFO_ARG.equals(arg)) {

            // Case: --strip-native-debug-symbols keep-debuginfo-files

            hasKeepDebugInfo = true;

        } else if (arg.startsWith(KEEP_DEBUG_INFO_ARG)) {

            // Case: --strip-native-debug-symbols keep-debuginfo-files=foo

            String[] tokens = arg.split("=");

            if (tokens.length != 2 || !KEEP_DEBUG_INFO_ARG.equals(tokens[0])) {

                throw new IllegalArgumentException(

                        PluginsResourceBundle.getMessage(resourceBundle,

                                                         NAME + ".iae", NAME, arg));

            }

            hasKeepDebugInfo = true;

            debuginfoExt = tokens[1];

        }

        if (EXCLUDE_DEBUG_INFO_ARG.equals(arg) || arg.startsWith(EXCLUDE_DEBUG_INFO_ARG + "=")) {

            // Case: --strip-native-debug-symbols exclude-debuginfo-files[=something]

            hasOmitDebugInfo = true;

        }

        if (arg.startsWith(STRIP_CMD_ARG)) {

            // Case: --strip-native-debug-symbols objcopy=<path/to/objcopy

            String[] tokens = arg.split("=");

            if (tokens.length != 2 || !STRIP_CMD_ARG.equals(tokens[0])) {

                throw new IllegalArgumentException(

                        PluginsResourceBundle.getMessage(resourceBundle,

                                                         NAME + ".iae", NAME, arg));

            }

            if (withChecks) {

                validateStripArg(tokens[1]);

            }

            stripBin = tokens[1];

        }

        // Cases (combination of options):

        //   --strip-native-debug-symbols keep-debuginfo-files:objcopy=</objcpy/path>

        //   --strip-native-debug-symbols keep-debuginfo-files=ext:objcopy=</objcpy/path>

        //   --strip-native-debug-symbols exclude-debuginfo-files:objcopy=</objcpy/path>

        String stripArg = config.remove(STRIP_CMD_ARG);

        if (stripArg != null && withChecks) {

            validateStripArg(stripArg);

        }

        if (stripArg != null) {

            stripBin = stripArg;

        }

        // Case (reversed combination)

        //   --strip-native-debug-symbols objcopy=</objcpy/path>:keep-debuginfo-files=ext

        // Note: cases like the following are not allowed by the parser

        //   --strip-native-debug-symbols objcopy=</objcpy/path>:keep-debuginfo-files

        //   --strip-native-debug-symbols objcopy=</objcpy/path>:exclude-debuginfo-files

        String keepDebugInfo = config.remove(KEEP_DEBUG_INFO_ARG);

        if (keepDebugInfo != null) {

            hasKeepDebugInfo = true;

            debuginfoExt = keepDebugInfo;

        }

        if ((hasKeepDebugInfo || includeDebugSymbols) && hasOmitDebugInfo) {

            // Cannot keep and omit debug info at the same time. Note that

            // includeDebugSymbols might already be true if configure is being run

            // on the same plugin instance multiple times. Plugin option can

            // repeat.

            throw new IllegalArgumentException(

                    PluginsResourceBundle.getMessage(resourceBundle,

                                                     NAME + ".iae.conflict",

                                                     NAME,

                                                     EXCLUDE_DEBUG_INFO_ARG,

                                                     KEEP_DEBUG_INFO_ARG));

        }

        if (!arg.startsWith(STRIP_CMD_ARG) &&

            !arg.startsWith(KEEP_DEBUG_INFO_ARG) &&

            !arg.startsWith(EXCLUDE_DEBUG_INFO_ARG)) {

            // unknown arg value; case --strip-native-debug-symbols foobar

            throw new IllegalArgumentException(

                    PluginsResourceBundle.getMessage(resourceBundle,

                                                     NAME + ".iae", NAME, arg));

        }

        if (!config.isEmpty()) {

            // extraneous values; --strip-native-debug-symbols keep-debuginfo-files:foo=bar

            throw new IllegalArgumentException(

                    PluginsResourceBundle.getMessage(resourceBundle,

                                                     NAME + ".iae", NAME,

                                                     config.toString()));

        }

        includeDebugSymbols = hasKeepDebugInfo;

    }

    private void validateStripArg(String stripArg) throws IllegalArgumentException {

        try {

            Path strip = Paths.get(stripArg); // verify it's a resonable path

            if (!Files.isExecutable(strip)) {

                throw new IllegalArgumentException(

                        PluginsResourceBundle.getMessage(resourceBundle,

                                                         NAME + ".invalidstrip",

                                                         stripArg));

            }

        } catch (InvalidPathException e) {

            throw new IllegalArgumentException(

                    PluginsResourceBundle.getMessage(resourceBundle,

                                                     NAME + ".invalidstrip",

                                                     e.getInput()));

        }

    }

    private static class StrippedDebugInfoBinaryBuilder {

        private final boolean includeDebug;

        private final String debugExt;

        private final ObjCopyCmdBuilder cmdBuilder;

        private final String strip;

        private StrippedDebugInfoBinaryBuilder(boolean includeDebug,

                                               String debugExt,

                                               ObjCopyCmdBuilder cmdBuilder,

                                               String strip) {

            this.includeDebug = includeDebug;

            this.debugExt = debugExt;

            this.cmdBuilder = cmdBuilder;

            this.strip = strip;

        }

        private Optional<StrippedDebugInfoBinary> build(ResourcePoolEntry resource) {

            Path tempDir = null;

            Optional<ResourcePoolEntry> debugInfo = Optional.empty();

            try {

                Path resPath = Paths.get(resource.path());

                String relativeFileName = resPath.getFileName().toString();

                tempDir = Files.createTempDirectory(NAME + relativeFileName);

                Path resourceFileBinary = tempDir.resolve(relativeFileName);

                String relativeDbgFileName = relativeFileName + "." + debugExt;

                Files.write(resourceFileBinary, resource.contentBytes());

                Path resourceFileDebugSymbols;

                if (includeDebug) {

                    resourceFileDebugSymbols = tempDir.resolve(Paths.get(relativeDbgFileName));

                    String debugEntryPath = resource.path() + "." + debugExt;

                    byte[] debugInfoBytes = createDebugSymbolsFile(resourceFileBinary,

                                           resourceFileDebugSymbols,

                                           relativeDbgFileName);

                    if (debugInfoBytes != null) {

                        ResourcePoolEntry debugEntry = ResourcePoolEntry.create(

                                                                debugEntryPath,

                                                                resource.type(),

                                                                debugInfoBytes);

                        debugInfo = Optional.of(debugEntry);

                    }

                }

                if (!stripBinary(resourceFileBinary)) {

                    if (DEBUG) {

                        System.err.println("DEBUG: Stripping debug info failed.");

                    }

                    return Optional.empty();

                }

                if (includeDebug && !addGnuDebugLink(tempDir,

                                                     relativeFileName,

                                                     relativeDbgFileName)) {

                    if (DEBUG) {

                        System.err.println("DEBUG: Creating debug link failed.");

                    }

                    return Optional.empty();

                }

                byte[] strippedBytes = Files.readAllBytes(resourceFileBinary);

                ResourcePoolEntry strippedResource = resource.copyWithContent(strippedBytes);

                return Optional.of(new StrippedDebugInfoBinary(strippedResource, debugInfo));

            } catch (IOException | InterruptedException e) {

                throw new PluginException(e);

            } finally {

                if (tempDir != null) {

                    deleteDirRecursivelyIgnoreResult(tempDir);

                }

            }

        }

        /*

         *  Equivalent of 'objcopy -g binFile'. Returning true iff stripping of the binary

         *  succeeded.

         */

        private boolean stripBinary(Path binFile)

                throws InterruptedException, IOException {

            String filePath = binFile.toAbsolutePath().toString();

            List<String> stripCmdLine = cmdBuilder.build(strip, STRIP_DEBUG_SYMS_OPT,

                                                     filePath);

            ProcessBuilder builder = createProcessBuilder(stripCmdLine);

            Process stripProc = builder.start();

            int retval = stripProc.waitFor();

            return retval == 0;

        }

        /*

         *  Equivalent of 'objcopy --add-gnu-debuglink=relativeDbgFileName binFile'.

         *  Returning true iff adding the debug link succeeded.

         */

        private boolean addGnuDebugLink(Path currDir,

                                        String binFile,

                                        String relativeDbgFileName)

                                                throws InterruptedException, IOException {

            List<String> addDbgLinkCmdLine = cmdBuilder.build(strip, ADD_DEBUG_LINK_OPT +

                                                     "=" + relativeDbgFileName,

                                                     binFile);

            ProcessBuilder builder = createProcessBuilder(addDbgLinkCmdLine);

            builder.directory(currDir.toFile());

            Process stripProc = builder.start();

            int retval = stripProc.waitFor();

            return retval == 0;

        }

        /*

         *  Equivalent of 'objcopy --only-keep-debug binPath debugPath'.

         *  Returning the bytes of the file containing debug symbols.

         */

        private byte[] createDebugSymbolsFile(Path binPath,

                                              Path debugPath,

                                              String dbgFileName) throws InterruptedException,

                                                                         IOException {

            String filePath = binPath.toAbsolutePath().toString();

            String dbgPath = debugPath.toAbsolutePath().toString();

            List<String> createLinkCmdLine = cmdBuilder.build(strip,

                                                     ONLY_KEEP_DEBUG_SYMS_OPT,

                                                     filePath,

                                                     dbgPath);

            ProcessBuilder builder = createProcessBuilder(createLinkCmdLine);

            Process stripProc = builder.start();

            int retval = stripProc.waitFor();

            if (retval != 0) {

                if (DEBUG) {

                    System.err.println("DEBUG: Creating debuginfo file failed.");

                }

                return null;

            } else {

                return Files.readAllBytes(debugPath);

            }

        }

        private ProcessBuilder createProcessBuilder(List<String> cmd) {

            ProcessBuilder builder = new ProcessBuilder(cmd);

            builder.redirectError(Redirect.INHERIT);

            builder.redirectOutput(Redirect.INHERIT);

            return builder;

        }

        private void deleteDirRecursivelyIgnoreResult(Path tempDir) {

            try {

                Files.walkFileTree(tempDir, new SimpleFileVisitor<Path>() {

                    @Override

                    public FileVisitResult visitFile(Path file,

                            BasicFileAttributes attrs) throws IOException {

                        Files.delete(file);

                        return FileVisitResult.CONTINUE;

                    }

                    @Override

                    public FileVisitResult postVisitDirectory(Path dir,

                            IOException exc) throws IOException {

                        Files.delete(dir);

                        return FileVisitResult.CONTINUE;

                    }

                });

            } catch (IOException e) {

                // ignore deleting the temp dir

            }

        }

    }

    private static class StrippedDebugInfoBinary {

        private final ResourcePoolEntry strippedBinary;

        private final Optional<ResourcePoolEntry> debugSymbols;

        private StrippedDebugInfoBinary(ResourcePoolEntry strippedBinary,

                                        Optional<ResourcePoolEntry> debugSymbols) {

            this.strippedBinary = Objects.requireNonNull(strippedBinary);

            this.debugSymbols = Objects.requireNonNull(debugSymbols);

        }

        public ResourcePoolEntry strippedBinary() {

            return strippedBinary;

        }

        public Optional<ResourcePoolEntry> debugSymbols() {

            return debugSymbols;

        }

    }

    // For better testing using mocked objcopy

    public static interface ObjCopyCmdBuilder {

        List<String> build(String objCopy, String...options);

    }

    private static final class DefaultObjCopyCmdBuilder implements ObjCopyCmdBuilder {

        @Override

        public List<String> build(String objCopy, String...options) {

            List<String> cmdList = new ArrayList<>();

            cmdList.add(objCopy);

            if (options.length > 0) {

                cmdList.addAll(Arrays.asList(options));

            }

            return cmdList;

        }

    }

}