Java tutorial
/* * Copyright 2013-present Facebook, Inc. * * Licensed 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 com.facebook.buck.zip; import com.facebook.buck.io.MoreFiles; import com.facebook.buck.io.MorePosixFilePermissions; import com.facebook.buck.io.ProjectFilesystem; import com.facebook.buck.util.MoreCollectors; import com.google.common.base.Charsets; import com.google.common.collect.ImmutableList; import com.google.common.io.ByteStreams; import org.apache.commons.compress.archivers.zip.ZipArchiveEntry; import org.apache.commons.compress.archivers.zip.ZipFile; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.nio.file.Files; import java.nio.file.Path; import java.nio.file.attribute.PosixFilePermission; import java.util.Enumeration; import java.util.Set; public class Unzip { /** Utility class: do not instantiate. */ private Unzip() { } public enum ExistingFileMode { OVERWRITE, OVERWRITE_AND_CLEAN_DIRECTORIES, } /** * Unzips a file to a destination and returns the paths of the written files. */ public static ImmutableList<Path> extractZipFile(Path zipFile, ProjectFilesystem filesystem, Path relativePath, ExistingFileMode existingFileMode) throws IOException { // if requested, clean before extracting if (existingFileMode == ExistingFileMode.OVERWRITE_AND_CLEAN_DIRECTORIES) { try (ZipFile zip = new ZipFile(zipFile.toFile())) { Enumeration<ZipArchiveEntry> entries = zip.getEntries(); while (entries.hasMoreElements()) { ZipArchiveEntry entry = entries.nextElement(); filesystem.deleteRecursivelyIfExists(relativePath.resolve(entry.getName())); } } } ImmutableList.Builder<Path> filesWritten = ImmutableList.builder(); try (ZipFile zip = new ZipFile(zipFile.toFile())) { Enumeration<ZipArchiveEntry> entries = zip.getEntries(); while (entries.hasMoreElements()) { ZipArchiveEntry entry = entries.nextElement(); String fileName = entry.getName(); Path target = relativePath.resolve(fileName); // TODO(bolinfest): Keep track of which directories have already been written to avoid // making unnecessary Files.createDirectories() calls. In practice, a single zip file will // have many entries in the same directory. if (entry.isDirectory()) { // Create the directory and all its parent directories filesystem.mkdirs(target); } else { // Create parent folder filesystem.createParentDirs(target); filesWritten.add(target); // Write file try (InputStream is = zip.getInputStream(entry)) { if (entry.isUnixSymlink()) { filesystem.createSymLink(target, filesystem.getPath(new String(ByteStreams.toByteArray(is), Charsets.UTF_8)), /* force */ true); } else { try (OutputStream out = filesystem.newFileOutputStream(target)) { ByteStreams.copy(is, out); } } } // restore mtime for the file filesystem.resolve(target).toFile().setLastModified(entry.getTime()); // TODO(shs96c): Implement what the comment below says we should do. // // Sets the file permissions of the output file given the information in {@code entry}'s // extra data field. According to the docs at // http://www.opensource.apple.com/source/zip/zip-6/unzip/unzip/proginfo/extra.fld there // are two extensions that might support file permissions: Acorn and ASi UNIX. We shall // assume that inputs are not from an Acorn SparkFS. The relevant section from the docs: // // <pre> // The following is the layout of the ASi extra block for Unix. The // local-header and central-header versions are identical. // (Last Revision 19960916) // // Value Size Description // ----- ---- ----------- // (Unix3) 0x756e Short tag for this extra block type ("nu") // TSize Short total data size for this block // CRC Long CRC-32 of the remaining data // Mode Short file permissions // SizDev Long symlink'd size OR major/minor dev num // UID Short user ID // GID Short group ID // (var.) variable symbolic link filename // // Mode is the standard Unix st_mode field from struct stat, containing // user/group/other permissions, setuid/setgid and symlink info, etc. // </pre> // // From the stat man page, we see that the following mask values are defined for the file // permissions component of the st_mode field: // // <pre> // S_ISUID 0004000 set-user-ID bit // S_ISGID 0002000 set-group-ID bit (see below) // S_ISVTX 0001000 sticky bit (see below) // // S_IRWXU 00700 mask for file owner permissions // // S_IRUSR 00400 owner has read permission // S_IWUSR 00200 owner has write permission // S_IXUSR 00100 owner has execute permission // // S_IRWXG 00070 mask for group permissions // S_IRGRP 00040 group has read permission // S_IWGRP 00020 group has write permission // S_IXGRP 00010 group has execute permission // // S_IRWXO 00007 mask for permissions for others // (not in group) // S_IROTH 00004 others have read permission // S_IWOTH 00002 others have write permission // S_IXOTH 00001 others have execute permission // </pre> // // For the sake of our own sanity, we're going to assume that no-one is using symlinks, // but we'll check and throw if they are. // // Before we do anything, we should check the header ID. Pfft! // // Having jumped through all these hoops, it turns out that InfoZIP's "unzip" store the // values in the external file attributes of a zip entry (found in the zip's central // directory) assuming that the OS creating the zip was one of an enormous list that // includes UNIX but not Windows, it first searches for the extra fields, and if not found // falls through to a code path that supports MS-DOS and which stores the UNIX file // attributes in the upper 16 bits of the external attributes field. // // We'll support neither approach fully, but we encode whether this file was executable // via storing 0100 in the fields that are typically used by zip implementations to store // POSIX permissions. If we find it was executable, use the platform independent java // interface to make this unpacked file executable. Set<PosixFilePermission> permissions = MorePosixFilePermissions .fromMode(entry.getExternalAttributes() >> 16); if (permissions.contains(PosixFilePermission.OWNER_EXECUTE)) { MoreFiles.makeExecutable(filesystem.resolve(target)); } } } } return filesWritten.build(); } public static ImmutableList<Path> extractZipFile(Path zipFile, ProjectFilesystem filesystem, ExistingFileMode existingFileMode) throws IOException { return extractZipFile(zipFile, filesystem, filesystem.getPath(""), existingFileMode); } public static ImmutableList<Path> extractZipFile(Path zipFile, final Path destination, ExistingFileMode existingFileMode) throws IOException { // Create output directory if it does not exist Files.createDirectories(destination); return extractZipFile(zipFile, new ProjectFilesystem(destination), destination.getFileSystem().getPath(""), existingFileMode).stream().map(input -> destination.resolve(input).toAbsolutePath()) .collect(MoreCollectors.toImmutableList()); } }