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17 package org.apache.logging.log4j.core.util;
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19 import org.apache.logging.log4j.util.Strings;
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25 public final class Transform {
26
27 private static final String CDATA_START = "<![CDATA[";
28 private static final String CDATA_END = "]]>";
29 private static final String CDATA_PSEUDO_END = "]]>";
30 private static final String CDATA_EMBEDED_END = CDATA_END + CDATA_PSEUDO_END + CDATA_START;
31 private static final int CDATA_END_LEN = CDATA_END.length();
32
33 private Transform() {
34 }
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45 public static String escapeHtmlTags(final String input) {
46
47
48
49 if (Strings.isEmpty(input)
50 || (input.indexOf('"') == -1 &&
51 input.indexOf('&') == -1 &&
52 input.indexOf('<') == -1 &&
53 input.indexOf('>') == -1)) {
54 return input;
55 }
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57
58
59
60 final StringBuilder buf = new StringBuilder(input.length() + 6);
61
62 final int len = input.length();
63 for (int i = 0; i < len; i++) {
64 final char ch = input.charAt(i);
65 if (ch > '>') {
66 buf.append(ch);
67 } else if (ch == '<') {
68 buf.append("<");
69 } else if (ch == '>') {
70 buf.append(">");
71 } else if (ch == '&') {
72 buf.append("&");
73 } else if (ch == '"') {
74 buf.append(""");
75 } else {
76 buf.append(ch);
77 }
78 }
79 return buf.toString();
80 }
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91 public static void appendEscapingCData(final StringBuilder buf, final String str) {
92 if (str != null) {
93 int end = str.indexOf(CDATA_END);
94 if (end < 0) {
95 buf.append(str);
96 } else {
97 int start = 0;
98 while (end > -1) {
99 buf.append(str.substring(start, end));
100 buf.append(CDATA_EMBEDED_END);
101 start = end + CDATA_END_LEN;
102 if (start < str.length()) {
103 end = str.indexOf(CDATA_END, start);
104 } else {
105 return;
106 }
107 }
108 buf.append(str.substring(start));
109 }
110 }
111 }
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120 public static String escapeJsonControlCharacters(final String input) {
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126 if (Strings.isEmpty(input)
127 || (input.indexOf('"') == -1 &&
128 input.indexOf('\\') == -1 &&
129 input.indexOf('/') == -1 &&
130 input.indexOf('\b') == -1 &&
131 input.indexOf('\f') == -1 &&
132 input.indexOf('\n') == -1 &&
133 input.indexOf('\r') == -1 &&
134 input.indexOf('\t') == -1)) {
135 return input;
136 }
137
138 final StringBuilder buf = new StringBuilder(input.length() + 6);
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140 final int len = input.length();
141 for (int i = 0; i < len; i++) {
142 final char ch = input.charAt(i);
143 final String escBs = "\\";
144 switch (ch) {
145 case '"':
146 buf.append(escBs);
147 buf.append(ch);
148 break;
149 case '\\':
150 buf.append(escBs);
151 buf.append(ch);
152 break;
153 case '/':
154 buf.append(escBs);
155 buf.append(ch);
156 break;
157 case '\b':
158 buf.append(escBs);
159 buf.append('b');
160 break;
161 case '\f':
162 buf.append(escBs);
163 buf.append('f');
164 break;
165 case '\n':
166 buf.append(escBs);
167 buf.append('n');
168 break;
169 case '\r':
170 buf.append(escBs);
171 buf.append('r');
172 break;
173 case '\t':
174 buf.append(escBs);
175 buf.append('t');
176 break;
177 default:
178 buf.append(ch);
179 }
180 }
181 return buf.toString();
182 }
183 }