1 /*
2 * Copyright (c) 2008, 2009, 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 sun.nio.fs;
27
28 import java.nio.file.attribute.*;
29 import java.util.*;
30 import java.io.IOException;
31
32 /**
33 * Linux implementation of FileStore
34 */
35
36 class LinuxFileStore
37 extends UnixFileStore
38 {
39 // used when checking if extended attributes are enabled or not
40 private volatile boolean xattrChecked;
41 private volatile boolean xattrEnabled;
42
43 LinuxFileStore(UnixPath file) throws IOException {
44 super(file);
45 }
46
47 LinuxFileStore(UnixFileSystem fs, UnixMountEntry entry) throws IOException {
48 super(fs, entry);
49 }
50
51 /**
52 * Finds, and returns, the mount entry for the file system where the file
53 * resides.
54 */
55 @Override
56 UnixMountEntry findMountEntry() throws IOException {
57 LinuxFileSystem fs = (LinuxFileSystem)file().getFileSystem();
58
59 // step 1: get realpath
60 UnixPath path = null;
61 try {
62 byte[] rp = UnixNativeDispatcher.realpath(file());
63 path = new UnixPath(fs, rp);
64 } catch (UnixException x) {
65 x.rethrowAsIOException(file());
66 }
67
68 // step 2: find mount point
69 UnixPath parent = path.getParent();
70 while (parent != null) {
71 UnixFileAttributes attrs = null;
72 try {
73 attrs = UnixFileAttributes.get(parent, true);
74 } catch (UnixException x) {
75 x.rethrowAsIOException(parent);
76 }
77 if (attrs.dev() != dev())
78 break;
79 path = parent;
80 parent = parent.getParent();
81 }
82
83 // step 3: lookup mounted file systems (use /proc/mounts to ensure we
84 // find the file system even when not in /etc/mtab)
85 byte[] dir = path.asByteArray();
86 for (UnixMountEntry entry: fs.getMountEntries("/proc/mounts")) {
87 if (Arrays.equals(dir, entry.dir()))
88 return entry;
89 }
90
91 throw new IOException("Mount point not found");
92 }
93
94 // returns true if extended attributes enabled on file system where given
95 // file resides, returns false if disabled or unable to determine.
96 private boolean isExtendedAttributesEnabled(UnixPath path) {
97 try {
98 int fd = path.openForAttributeAccess(false);
99 try {
100 // fgetxattr returns size if called with size==0
101 LinuxNativeDispatcher.fgetxattr(fd, "user.java".getBytes(), 0L, 0);
102 return true;
103 } catch (UnixException e) {
104 // attribute does not exist
105 if (e.errno() == UnixConstants.ENODATA)
106 return true;
107 } finally {
108 UnixNativeDispatcher.close(fd);
109 }
110 } catch (IOException ignore) {
111 // nothing we can do
112 }
113 return false;
114 }
115
116 @Override
117 public boolean supportsFileAttributeView(Class<? extends FileAttributeView> type) {
118 // support DosFileAttributeView and UserDefinedAttributeView if extended
119 // attributes enabled
120 if (type == DosFileAttributeView.class ||
121 type == UserDefinedFileAttributeView.class)
122 {
123 // lookup fstypes.properties
124 FeatureStatus status = checkIfFeaturePresent("user_xattr");
125 if (status == FeatureStatus.PRESENT)
126 return true;
127 if (status == FeatureStatus.NOT_PRESENT)
128 return false;
129
130 // if file system is mounted with user_xattr option then assume
131 // extended attributes are enabled
132 if ((entry().hasOption("user_xattr")))
133 return true;
134
135 // user_xattr option not present but we special-case ext3/4 as we
136 // know that extended attributes are not enabled by default.
137 if (entry().fstype().equals("ext3") || entry().fstype().equals("ext4"))
138 return false;
139
140 // not ext3/4 so probe mount point
141 if (!xattrChecked) {
142 UnixPath dir = new UnixPath(file().getFileSystem(), entry().dir());
143 xattrEnabled = isExtendedAttributesEnabled(dir);
144 xattrChecked = true;
145 }
146 return xattrEnabled;
147 }
148 return super.supportsFileAttributeView(type);
149 }
150
151 @Override
152 public boolean supportsFileAttributeView(String name) {
153 if (name.equals("dos"))
154 return supportsFileAttributeView(DosFileAttributeView.class);
155 if (name.equals("user"))
156 return supportsFileAttributeView(UserDefinedFileAttributeView.class);
157 return super.supportsFileAttributeView(name);
158 }
159 }