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| 1 | /* | ||
| 2 | * Copyright (c) 2007, 2011, Oracle and/or its affiliates. All rights reserved. | ||
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. | ||
| 4 | * | ||
| 5 | * This code is free software; you can redistribute it and/or modify it | ||
| 6 | * under the terms of the GNU General Public License version 2 only, as | ||
| 7 | * published by the Free Software Foundation. Oracle designates this | ||
| 8 | * particular file as subject to the "Classpath" exception as provided | ||
| 9 | * by Oracle in the LICENSE file that accompanied this code. | ||
| 10 | * | ||
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT | ||
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | ||
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | ||
| 14 | * version 2 for more details (a copy is included in the LICENSE file that | ||
| 15 | * accompanied this code). | ||
| 16 | * | ||
| 17 | * You should have received a copy of the GNU General Public License version | ||
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, | ||
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. | ||
| 20 | * | ||
| 21 | * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | ||
| 22 | * or visit www.oracle.com if you need additional information or have any | ||
| 23 | * questions. | ||
| 24 | */ | ||
| 25 | |||
| 26 | package java.nio.file; | ||
| 27 | |||
| 28 | import java.nio.file.attribute.*; | ||
| 29 | import java.io.IOException; | ||
| 30 | import java.util.*; | ||
| 31 | import sun.nio.fs.BasicFileAttributesHolder; | ||
| 32 | |||
| 33 | /** | ||
| 34 | * Simple file tree walker that works in a similar manner to nftw(3C). | ||
| 35 | * | ||
| 36 | * @see Files#walkFileTree | ||
| 37 | */ | ||
| 38 | |||
| 39 | class FileTreeWalker { | ||
| 40 | private final boolean followLinks; | ||
| 41 | private final LinkOption[] linkOptions; | ||
| 42 | private final FileVisitor<? super Path> visitor; | ||
| 43 | private final int maxDepth; | ||
| 44 | |||
| 45 | FileTreeWalker(Set<FileVisitOption> options, | ||
| 46 | FileVisitor<? super Path> visitor, | ||
| 47 | int maxDepth) | ||
| 48 | { | ||
| 49 | boolean fl = false; | ||
| 50 | for (FileVisitOption option: options) { | ||
| 51 | // will throw NPE if options contains null | ||
| 52 | switch (option) { | ||
| 53 | case FOLLOW_LINKS : fl = true; break; | ||
| 54 | default: | ||
| 55 | throw new AssertionError("Should not get here"); | ||
| 56 | } | ||
| 57 | } | ||
| 58 | this.followLinks = fl; | ||
| 59 | this.linkOptions = (fl) ? new LinkOption[0] : | ||
| 60 | new LinkOption[] { LinkOption.NOFOLLOW_LINKS }; | ||
| 61 | this.visitor = visitor; | ||
| 62 | this.maxDepth = maxDepth; | ||
| 63 | } | ||
| 64 | |||
| 65 | /** | ||
| 66 | * Walk file tree starting at the given file | ||
| 67 | */ | ||
| 68 | void walk(Path start) throws IOException { | ||
| 69 | FileVisitResult result = walk(start, | ||
| 70 | 0, | ||
| 71 | new ArrayList<AncestorDirectory>()); | ||
| 72 | Objects.requireNonNull(result, "FileVisitor returned null"); | ||
| 73 | } | ||
| 74 | |||
| 75 | /** | ||
| 76 | * @param file | ||
| 77 | * the directory to visit | ||
| 78 | * @param depth | ||
| 79 | * depth remaining | ||
| 80 | * @param ancestors | ||
| 81 | * use when cycle detection is enabled | ||
| 82 | */ | ||
| 83 | private FileVisitResult walk(Path file, | ||
| 84 | int depth, | ||
| 85 | List<AncestorDirectory> ancestors) | ||
| 86 | throws IOException | ||
| 87 | { | ||
| 88 | // if attributes are cached then use them if possible | ||
| 89 | BasicFileAttributes attrs = null; | ||
| 90 | if ((depth > 0) && | ||
| 91 | (file instanceof BasicFileAttributesHolder) && | ||
| 92 | (System.getSecurityManager() == null)) | ||
| 93 | { | ||
| 94 | BasicFileAttributes cached = ((BasicFileAttributesHolder)file).get(); | ||
| 95 | if (!followLinks || !cached.isSymbolicLink()) | ||
| 96 | attrs = cached; | ||
| 97 | } | ||
| 98 | IOException exc = null; | ||
| 99 | |||
| 100 | // attempt to get attributes of file. If fails and we are following | ||
| 101 | // links then a link target might not exist so get attributes of link | ||
| 102 | if (attrs == null) { | ||
| 103 | try { | ||
| 104 | try { | ||
| 105 | attrs = Files.readAttributes(file, BasicFileAttributes.class, linkOptions); | ||
| 106 | } catch (IOException x1) { | ||
| 107 | if (followLinks) { | ||
| 108 | try { | ||
| 109 | attrs = Files.readAttributes(file, | ||
| 110 | BasicFileAttributes.class, | ||
| 111 | LinkOption.NOFOLLOW_LINKS); | ||
| 112 | } catch (IOException x2) { | ||
| 113 | exc = x2; | ||
| 114 | } | ||
| 115 | } else { | ||
| 116 | exc = x1; | ||
| 117 | } | ||
| 118 | } | ||
| 119 | } catch (SecurityException x) { | ||
| 120 | // If access to starting file is denied then SecurityException | ||
| 121 | // is thrown, otherwise the file is ignored. | ||
| 122 | if (depth == 0) | ||
| 123 | throw x; | ||
| 124 | return FileVisitResult.CONTINUE; | ||
| 125 | } | ||
| 126 | } | ||
| 127 | |||
| 128 | // unable to get attributes of file | ||
| 129 | if (exc != null) { | ||
| 130 | return visitor.visitFileFailed(file, exc); | ||
| 131 | } | ||
| 132 | |||
| 133 | // at maximum depth or file is not a directory | ||
| 134 | if (depth >= maxDepth || !attrs.isDirectory()) { | ||
| 135 | return visitor.visitFile(file, attrs); | ||
| 136 | } | ||
| 137 | |||
| 138 | // check for cycles when following links | ||
| 139 | if (followLinks) { | ||
| 140 | Object key = attrs.fileKey(); | ||
| 141 | |||
| 142 | // if this directory and ancestor has a file key then we compare | ||
| 143 | // them; otherwise we use less efficient isSameFile test. | ||
| 144 | for (AncestorDirectory ancestor: ancestors) { | ||
| 145 | Object ancestorKey = ancestor.fileKey(); | ||
| 146 | if (key != null && ancestorKey != null) { | ||
| 147 | if (key.equals(ancestorKey)) { | ||
| 148 | // cycle detected | ||
| 149 | return visitor.visitFileFailed(file, | ||
| 150 | new FileSystemLoopException(file.toString())); | ||
| 151 | } | ||
| 152 | } else { | ||
| 153 | boolean isSameFile = false; | ||
| 154 | try { | ||
| 155 | isSameFile = Files.isSameFile(file, ancestor.file()); | ||
| 156 | } catch (IOException x) { | ||
| 157 | // ignore | ||
| 158 | } catch (SecurityException x) { | ||
| 159 | // ignore | ||
| 160 | } | ||
| 161 | if (isSameFile) { | ||
| 162 | // cycle detected | ||
| 163 | return visitor.visitFileFailed(file, | ||
| 164 | new FileSystemLoopException(file.toString())); | ||
| 165 | } | ||
| 166 | } | ||
| 167 | } | ||
| 168 | |||
| 169 | ancestors.add(new AncestorDirectory(file, key)); | ||
| 170 | } | ||
| 171 | |||
| 172 | // visit directory | ||
| 173 | try { | ||
| 174 | DirectoryStream<Path> stream = null; | ||
| 175 | FileVisitResult result; | ||
| 176 | |||
| 177 | // open the directory | ||
| 178 | try { | ||
| 179 | stream = Files.newDirectoryStream(file); | ||
| 180 | } catch (IOException x) { | ||
| 181 | return visitor.visitFileFailed(file, x); | ||
| 182 | } catch (SecurityException x) { | ||
| 183 | // ignore, as per spec | ||
| 184 | return FileVisitResult.CONTINUE; | ||
| 185 | } | ||
| 186 | |||
| 187 | // the exception notified to the postVisitDirectory method | ||
| 188 | IOException ioe = null; | ||
| 189 | |||
| 190 | // invoke preVisitDirectory and then visit each entry | ||
| 191 | try { | ||
| 192 | result = visitor.preVisitDirectory(file, attrs); | ||
| 193 | if (result != FileVisitResult.CONTINUE) { | ||
| 194 | return result; | ||
| 195 | } | ||
| 196 | |||
| 197 | try { | ||
| 198 | for (Path entry: stream) { | ||
| 199 | result = walk(entry, depth+1, ancestors); | ||
| 200 | |||
| 201 | // returning null will cause NPE to be thrown | ||
| 202 | if (result == null || result == FileVisitResult.TERMINATE) | ||
| 203 | return result; | ||
| 204 | |||
| 205 | // skip remaining siblings in this directory | ||
| 206 | if (result == FileVisitResult.SKIP_SIBLINGS) | ||
| 207 | break; | ||
| 208 | } | ||
| 209 | } catch (DirectoryIteratorException e) { | ||
| 210 | // IOException will be notified to postVisitDirectory | ||
| 211 | ioe = e.getCause(); | ||
| 212 | } | ||
| 213 | } finally { | ||
| 214 | try { | ||
| 215 | stream.close(); | ||
| 216 | } catch (IOException e) { | ||
| 217 | // IOException will be notified to postVisitDirectory | ||
| 218 | if (ioe == null) | ||
| 219 | ioe = e; | ||
| 220 | } | ||
| 221 | } | ||
| 222 | |||
| 223 | // invoke postVisitDirectory last | ||
| 224 | return visitor.postVisitDirectory(file, ioe); | ||
| 225 | |||
| 226 | } finally { | ||
| 227 | // remove key from trail if doing cycle detection | ||
| 228 | if (followLinks) { | ||
| 229 | ancestors.remove(ancestors.size()-1); | ||
| 230 | } | ||
| 231 | } | ||
| 232 | } | ||
| 233 | |||
| 234 | private static class AncestorDirectory { | ||
| 235 | private final Path dir; | ||
| 236 | private final Object key; | ||
| 237 | AncestorDirectory(Path dir, Object key) { | ||
| 238 | this.dir = dir; | ||
| 239 | this.key = key; | ||
| 240 | } | ||
| 241 | Path file() { | ||
| 242 | return dir; | ||
| 243 | } | ||
| 244 | Object fileKey() { | ||
| 245 | return key; | ||
| 246 | } | ||
| 247 | } | ||
| 248 | } | ||