TempFileHelper.java revision 10767:eaa52ce531c3 
1/*
2 * Copyright (c) 2009, 2013, 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
26package java.nio.file;
27
28import java.util.Set;
29import java.util.EnumSet;
30import java.security.SecureRandom;
31import static java.security.AccessController.*;
32import java.io.IOException;
33import java.nio.file.attribute.FileAttribute;
34import java.nio.file.attribute.PosixFilePermission;
35import java.nio.file.attribute.PosixFilePermissions;
36import static java.nio.file.attribute.PosixFilePermission.*;
37import sun.security.action.GetPropertyAction;
38
39
40/**
41 * Helper class to support creation of temporary files and directories with
42 * initial attributes.
43 */
44
45class TempFileHelper {
46    private TempFileHelper() { }
47
48    // temporary directory location
49    private static final Path tmpdir =
50        Paths.get(doPrivileged(new GetPropertyAction("java.io.tmpdir")));
51
52    private static final boolean isPosix =
53        FileSystems.getDefault().supportedFileAttributeViews().contains("posix");
54
55    // file name generation, same as java.io.File for now
56    private static final SecureRandom random = new SecureRandom();
57    private static Path generatePath(String prefix, String suffix, Path dir) {
58        long n = random.nextLong();
59        n = (n == Long.MIN_VALUE) ? 0 : Math.abs(n);
60        Path name = dir.getFileSystem().getPath(prefix + Long.toString(n) + suffix);
61        // the generated name should be a simple file name
62        if (name.getParent() != null)
63            throw new IllegalArgumentException("Invalid prefix or suffix");
64        return dir.resolve(name);
65    }
66
67    // default file and directory permissions (lazily initialized)
68    private static class PosixPermissions {
69        static final FileAttribute<Set<PosixFilePermission>> filePermissions =
70            PosixFilePermissions.asFileAttribute(EnumSet.of(OWNER_READ, OWNER_WRITE));
71        static final FileAttribute<Set<PosixFilePermission>> dirPermissions =
72            PosixFilePermissions.asFileAttribute(EnumSet
73                .of(OWNER_READ, OWNER_WRITE, OWNER_EXECUTE));
74    }
75
76    /**
77     * Creates a file or directory in the given directory (or in the
78     * temporary directory if dir is {@code null}).
79     */
80    private static Path create(Path dir,
81                               String prefix,
82                               String suffix,
83                               boolean createDirectory,
84                               FileAttribute<?>[] attrs)
85        throws IOException
86    {
87        if (prefix == null)
88            prefix = "";
89        if (suffix == null)
90            suffix = (createDirectory) ? "" : ".tmp";
91        if (dir == null)
92            dir = tmpdir;
93
94        // in POSIX environments use default file and directory permissions
95        // if initial permissions not given by caller.
96        if (isPosix && (dir.getFileSystem() == FileSystems.getDefault())) {
97            if (attrs.length == 0) {
98                // no attributes so use default permissions
99                attrs = new FileAttribute<?>[1];
100                attrs[0] = (createDirectory) ? PosixPermissions.dirPermissions :
101                                               PosixPermissions.filePermissions;
102            } else {
103                // check if posix permissions given; if not use default
104                boolean hasPermissions = false;
105                for (int i=0; i<attrs.length; i++) {
106                    if (attrs[i].name().equals("posix:permissions")) {
107                        hasPermissions = true;
108                        break;
109                    }
110                }
111                if (!hasPermissions) {
112                    FileAttribute<?>[] copy = new FileAttribute<?>[attrs.length+1];
113                    System.arraycopy(attrs, 0, copy, 0, attrs.length);
114                    attrs = copy;
115                    attrs[attrs.length-1] = (createDirectory) ?
116                        PosixPermissions.dirPermissions :
117                        PosixPermissions.filePermissions;
118                }
119            }
120        }
121
122        // loop generating random names until file or directory can be created
123        SecurityManager sm = System.getSecurityManager();
124        for (;;) {
125            Path f;
126            try {
127                f = generatePath(prefix, suffix, dir);
128            } catch (InvalidPathException e) {
129                // don't reveal temporary directory location
130                if (sm != null)
131                    throw new IllegalArgumentException("Invalid prefix or suffix");
132                throw e;
133            }
134            try {
135                if (createDirectory) {
136                    return Files.createDirectory(f, attrs);
137                } else {
138                    return Files.createFile(f, attrs);
139                }
140            } catch (SecurityException e) {
141                // don't reveal temporary directory location
142                if (dir == tmpdir && sm != null)
143                    throw new SecurityException("Unable to create temporary file or directory");
144                throw e;
145            } catch (FileAlreadyExistsException e) {
146                // ignore
147            }
148        }
149    }
150
151    /**
152     * Creates a temporary file in the given directory, or in the
153     * temporary directory if dir is {@code null}.
154     */
155    static Path createTempFile(Path dir,
156                               String prefix,
157                               String suffix,
158                               FileAttribute<?>[] attrs)
159        throws IOException
160    {
161        return create(dir, prefix, suffix, false, attrs);
162    }
163
164    /**
165     * Creates a temporary directory in the given directory, or in the
166     * temporary directory if dir is {@code null}.
167     */
168    static Path createTempDirectory(Path dir,
169                                    String prefix,
170                                    FileAttribute<?>[] attrs)
171        throws IOException
172    {
173        return create(dir, prefix, null, true, attrs);
174    }
175}
176