1 /*
2 * Copyright (C) 2005-2015 Schlichtherle IT Services.
3 * All rights reserved. Use is subject to license terms.
4 */
5 package net.java.truevfs.kernel.spec;
6
7 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
8 import net.java.truecommons.shed.QuotedUriSyntaxException;
9 import net.java.truecommons.shed.UriBuilder;
10
11 import javax.annotation.concurrent.Immutable;
12 import java.net.URI;
13 import java.net.URISyntaxException;
14
15 import static net.java.truevfs.kernel.spec.FsNodeName.SEPARATOR;
16 import static net.java.truevfs.kernel.spec.FsNodeName.SEPARATOR_CHAR;
17
18 /**
19 * Modifies a URI when parsing a file system {@linkplain FsNodePath node path},
20 * a {@linkplain FsMountPoint mount point} or an
21 * {@linkplain FsNodeName node name}.
22 *
23 * @author Christian Schlichtherle
24 */
25 @Immutable
26 public enum FsUriModifier {
27
28 /**
29 * The null modifier does nothing but ensure that the URI path is in normal
30 * form.
31 */
32 NULL {
33 @Override
34 URI modify(URI uri, PostFix fix) throws URISyntaxException {
35 if (uri.normalize() != uri)
36 throw new QuotedUriSyntaxException(uri, "URI path not in normal form");
37 return uri;
38 }
39 },
40
41 /**
42 * The canonicalize modifier applies a {@link PostFix post-fix} which
43 * depends on the class specific URI syntax.
44 */
45 CANONICALIZE {
46 @Override
47 URI modify(URI uri, PostFix fix) throws URISyntaxException {
48 return fix.modify(uri);
49 }
50 };
51
52 /**
53 * An idempotent function which modifies a URI.
54 *
55 * @param uri the URI to modify.
56 * @param fix the post-fix to apply if required.
57 * @return the modified URI.
58 */
59 abstract URI modify(URI uri, PostFix fix) throws URISyntaxException;
60
61 /**
62 * Post-fixes a URI when it gets
63 * {@link FsUriModifier#CANONICALIZE canonicalized}.
64 */
65 public enum PostFix {
66
67 /**
68 * The post-fix for an {@link FsNodePath} depends on the given URI:
69 * If the URI is opaque or not absolute or has a fragment component
70 * defined, nothing is modified.
71 * Otherwise, the following modifications are conducted:
72 * <ol>
73 * <li>If the URI path component starts with two separators, the
74 * substring following until the next separator is moved to the
75 * authority part of the URI.
76 * This behavior is intended to fix URIs returned by
77 * {@link java.io.File#toURI()}.
78 * <li>The URI path component gets truncated so that it does not end
79 * with {@link FsNodeName#SEPARATOR} whereby a trailing separator
80 * after a Windows-like drive letter is preserved.
81 * <li>An empty authority component in the scheme specific part gets
82 * truncated.
83 * </ol>
84 * <p>
85 * Note that this fix is not limited to Windows in order to make
86 * this function work identically on all platforms.
87 */
88 NODE_PATH {
89 @Override
90 @SuppressFBWarnings("ES_COMPARING_STRINGS_WITH_EQ")
91 URI modify(URI uri) throws URISyntaxException {
92 if (uri.isOpaque()
93 || !uri.isAbsolute()
94 || null != uri.getRawFragment())
95 return uri;
96 {
97 String a = uri.getRawAuthority();
98 String p = uri.getRawPath();
99 if (null == a && null != p && p.startsWith(TWO_SEPARATORS)) {
100 int i = p.indexOf(SEPARATOR_CHAR, 2);
101 if (2 <= i) {
102 a = p.substring(2, i);
103 p = p.substring(i);
104 }
105 uri = new UriBuilder(uri, true).authority(a).path(p).getUri();
106 }
107 uri = uri.normalize();
108 }
109 String s = uri.getScheme();
110 String a = uri.getRawAuthority();
111 String p = uri.getRawPath(), q = p;
112 for (int l; p.endsWith(SEPARATOR)
113 && ( 1 <=(l = p.length()) && null == s
114 || 2 <= l && ':' != p.charAt(l - 2)
115 || 3 <= l && !p.startsWith(SEPARATOR)
116 || 4 < l && p.startsWith(SEPARATOR)
117 || null != a); )
118 p = p.substring(0, l - 1);
119 return p != q
120 ? new UriBuilder(uri, true).path(p).getUri()
121 : uri;
122 }
123 },
124
125 /**
126 * The post-fix for an {@link FsMountPoint} just normalizes the given
127 * URI.
128 */
129 MOUNT_POINT {
130 @Override
131 URI modify(URI uri) {
132 return uri.normalize();
133 }
134 },
135
136 /**
137 * The post-fix for an {@link FsNodeName} depends on the given URI:
138 * If the URI is absolute or has an authority or a fragment component
139 * defined, nothing is modified.
140 * Otherwise, the URI path component gets truncated so that it does not
141 * start or end with {@link FsNodeName#SEPARATOR}.
142 */
143 NODE_NAME {
144 @Override
145 @SuppressFBWarnings("ES_COMPARING_STRINGS_WITH_EQ")
146 URI modify(URI uri) throws URISyntaxException {
147 uri = uri.normalize();
148 if (uri.isAbsolute()
149 || null != uri.getRawAuthority()
150 || null != uri.getRawFragment())
151 return uri;
152 String p = uri.getRawPath(), q = p;
153 while (p.startsWith(SEPARATOR))
154 p = p.substring(1);
155 while (p.endsWith(SEPARATOR))
156 p = p.substring(0, p.length() - 1);
157 return p == q
158 ? uri
159 : new UriBuilder(uri, true).path(p).getUri();
160 }
161 };
162
163 /**
164 * An idempotent function which modifies the given URI.
165 *
166 * @param uri the URI to modify.
167 * @return the modified URI.
168 */
169 abstract URI modify(URI uri) throws URISyntaxException;
170
171 private static final String TWO_SEPARATORS = SEPARATOR + SEPARATOR;
172 }
173 }