1 /*
2 * Copyright (c) 2008, 2018, 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 List<UnixMountEntry> procMountsEntries =
70 fs.getMountEntries("/proc/mounts");
71 UnixPath parent = path.getParent();
72 while (parent != null) {
73 UnixFileAttributes attrs = null;
74 try {
75 attrs = UnixFileAttributes.get(parent, true);
76 } catch (UnixException x) {
77 x.rethrowAsIOException(parent);
78 }
79 if (attrs.dev() != dev()) {
80 // step 3: lookup mounted file systems (use /proc/mounts to
81 // ensure we find the file system even when not in /etc/mtab)
82 byte[] dir = path.asByteArray();
83 for (UnixMountEntry entry : procMountsEntries) {
84 if (Arrays.equals(dir, entry.dir()))
85 return entry;
86 }
87 }
88 path = parent;
89 parent = parent.getParent();
90 }
91
92 // step 3: lookup mounted file systems (use /proc/mounts to
93 // ensure we find the file system even when not in /etc/mtab)
94 byte[] dir = path.asByteArray();
95 for (UnixMountEntry entry : procMountsEntries) {
96 if (Arrays.equals(dir, entry.dir()))
97 return entry;
98 }
99
100 throw new IOException("Mount point not found");
101 }
102
103 // returns true if extended attributes enabled on file system where given
104 // file resides, returns false if disabled or unable to determine.
105 private boolean isExtendedAttributesEnabled(UnixPath path) {
106 int fd = -1;
107 try {
108 fd = path.openForAttributeAccess(false);
109
110 // fgetxattr returns size if called with size==0
111 byte[] name = Util.toBytes("user.java");
112 LinuxNativeDispatcher.fgetxattr(fd, name, 0L, 0);
113 return true;
114 } catch (UnixException e) {
115 // attribute does not exist
116 if (e.errno() == UnixConstants.ENODATA)
117 return true;
118 } finally {
119 UnixNativeDispatcher.close(fd);
120 }
121 return false;
122 }
123
124 @Override
125 public boolean supportsFileAttributeView(Class<? extends FileAttributeView> type) {
126 // support DosFileAttributeView and UserDefinedAttributeView if extended
127 // attributes enabled
128 if (type == DosFileAttributeView.class ||
129 type == UserDefinedFileAttributeView.class)
130 {
131 // lookup fstypes.properties
132 FeatureStatus status = checkIfFeaturePresent("user_xattr");
133 if (status == FeatureStatus.PRESENT)
134 return true;
135 if (status == FeatureStatus.NOT_PRESENT)
136 return false;
137
138 // if file system is mounted with user_xattr option then assume
139 // extended attributes are enabled
140 if ((entry().hasOption("user_xattr")))
141 return true;
142
143 // for ext3 and ext4 user_xattr option is enabled by default so
144 // check for explicit disabling of this option
145 if (entry().fstype().equals("ext3") ||
146 entry().fstype().equals("ext4")) {
147 return !entry().hasOption("nouser_xattr");
148 }
149
150 // not ext3/4 so probe mount point
151 if (!xattrChecked) {
152 UnixPath dir = new UnixPath(file().getFileSystem(), entry().dir());
153 xattrEnabled = isExtendedAttributesEnabled(dir);
154 xattrChecked = true;
155 }
156 return xattrEnabled;
157 }
158 // POSIX attributes not supported on FAT
159 if (type == PosixFileAttributeView.class && entry().fstype().equals("vfat"))
160 return false;
161 return super.supportsFileAttributeView(type);
162 }
163
164 @Override
165 public boolean supportsFileAttributeView(String name) {
166 if (name.equals("dos"))
167 return supportsFileAttributeView(DosFileAttributeView.class);
168 if (name.equals("user"))
169 return supportsFileAttributeView(UserDefinedFileAttributeView.class);
170 return super.supportsFileAttributeView(name);
171 }
172 }