/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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).
 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package sun.nio.fs;

import java.nio.file.*;
import static java.nio.file.StandardOpenOption.*;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.io.IOException;
import java.util.*;
import jdk.internal.misc.Unsafe;

import static sun.nio.fs.WindowsNativeDispatcher.*;
import static sun.nio.fs.WindowsConstants.*;

Windows emulation of NamedAttributeView using Alternative Data Streams
/** * Windows emulation of NamedAttributeView using Alternative Data Streams */
class WindowsUserDefinedFileAttributeView extends AbstractUserDefinedFileAttributeView { private static final Unsafe unsafe = Unsafe.getUnsafe(); // syntax to address named streams private String join(String file, String name) { if (name == null) throw new NullPointerException("'name' is null"); return file + ":" + name; } private String join(WindowsPath file, String name) throws WindowsException { return join(file.getPathForWin32Calls(), name); } private final WindowsPath file; private final boolean followLinks; WindowsUserDefinedFileAttributeView(WindowsPath file, boolean followLinks) { this.file = file; this.followLinks = followLinks; } // enumerates the file streams using FindFirstStream/FindNextStream APIs. private List<String> listUsingStreamEnumeration() throws IOException { List<String> list = new ArrayList<>(); try { FirstStream first = FindFirstStream(file.getPathForWin32Calls()); if (first != null) { long handle = first.handle(); try { // first stream is always ::$DATA for files String name = first.name(); if (!name.equals("::$DATA")) { String[] segs = name.split(":"); list.add(segs[1]); } while ((name = FindNextStream(handle)) != null) { String[] segs = name.split(":"); list.add(segs[1]); } } finally { FindClose(handle); } } } catch (WindowsException x) { x.rethrowAsIOException(file); } return Collections.unmodifiableList(list); } @Override public List<String> list() throws IOException { if (System.getSecurityManager() != null) checkAccess(file.getPathForPermissionCheck(), true, false); return listUsingStreamEnumeration(); } @Override public int size(String name) throws IOException { if (System.getSecurityManager() != null) checkAccess(file.getPathForPermissionCheck(), true, false); // wrap with channel FileChannel fc = null; try { Set<OpenOption> opts = new HashSet<>(); opts.add(READ); if (!followLinks) opts.add(WindowsChannelFactory.OPEN_REPARSE_POINT); fc = WindowsChannelFactory .newFileChannel(join(file, name), null, opts, 0L); } catch (WindowsException x) { x.rethrowAsIOException(join(file.getPathForPermissionCheck(), name)); } try { long size = fc.size(); if (size > Integer.MAX_VALUE) throw new ArithmeticException("Stream too large"); return (int)size; } finally { fc.close(); } } @Override public int read(String name, ByteBuffer dst) throws IOException { if (System.getSecurityManager() != null) checkAccess(file.getPathForPermissionCheck(), true, false); // wrap with channel FileChannel fc = null; try { Set<OpenOption> opts = new HashSet<>(); opts.add(READ); if (!followLinks) opts.add(WindowsChannelFactory.OPEN_REPARSE_POINT); fc = WindowsChannelFactory .newFileChannel(join(file, name), null, opts, 0L); } catch (WindowsException x) { x.rethrowAsIOException(join(file.getPathForPermissionCheck(), name)); } // read to EOF (nothing we can do if I/O error occurs) try { if (fc.size() > dst.remaining()) throw new IOException("Stream too large"); int total = 0; while (dst.hasRemaining()) { int n = fc.read(dst); if (n < 0) break; total += n; } return total; } finally { fc.close(); } } @Override public int write(String name, ByteBuffer src) throws IOException { if (System.getSecurityManager() != null) checkAccess(file.getPathForPermissionCheck(), false, true); /** * Creating a named stream will cause the unnamed stream to be created * if it doesn't already exist. To avoid this we open the unnamed stream * for reading and hope it isn't deleted/moved while we create or * replace the named stream. Opening the file without sharing options * may cause sharing violations with other programs that are accessing * the unnamed stream. */ long handle = -1L; try { int flags = FILE_FLAG_BACKUP_SEMANTICS; if (!followLinks) flags |= FILE_FLAG_OPEN_REPARSE_POINT; handle = CreateFile(file.getPathForWin32Calls(), GENERIC_READ, (FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE), OPEN_EXISTING, flags); } catch (WindowsException x) { x.rethrowAsIOException(file); } try { Set<OpenOption> opts = new HashSet<>(); if (!followLinks) opts.add(WindowsChannelFactory.OPEN_REPARSE_POINT); opts.add(CREATE); opts.add(WRITE); opts.add(StandardOpenOption.TRUNCATE_EXISTING); FileChannel named = null; try { named = WindowsChannelFactory .newFileChannel(join(file, name), null, opts, 0L); } catch (WindowsException x) { x.rethrowAsIOException(join(file.getPathForPermissionCheck(), name)); } // write value (nothing we can do if I/O error occurs) try { int rem = src.remaining(); while (src.hasRemaining()) { named.write(src); } return rem; } finally { named.close(); } } finally { CloseHandle(handle); } } @Override public void delete(String name) throws IOException { if (System.getSecurityManager() != null) checkAccess(file.getPathForPermissionCheck(), false, true); String path = WindowsLinkSupport.getFinalPath(file, followLinks); String toDelete = join(path, name); try { DeleteFile(toDelete); } catch (WindowsException x) { x.rethrowAsIOException(toDelete); } } }