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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 char ch = ' ';
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63 final int len = input.length();
64 for (int i = 0; i < len; i++) {
65 ch = input.charAt(i);
66 if (ch > '>') {
67 buf.append(ch);
68 } else if (ch == '<') {
69 buf.append("<");
70 } else if (ch == '>') {
71 buf.append(">");
72 } else if (ch == '&') {
73 buf.append("&");
74 } else if (ch == '"') {
75 buf.append(""");
76 } else {
77 buf.append(ch);
78 }
79 }
80 return buf.toString();
81 }
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92 public static void appendEscapingCData(final StringBuilder buf, final String str) {
93 if (str != null) {
94 int end = str.indexOf(CDATA_END);
95 if (end < 0) {
96 buf.append(str);
97 } else {
98 int start = 0;
99 while (end > -1) {
100 buf.append(str.substring(start, end));
101 buf.append(CDATA_EMBEDED_END);
102 start = end + CDATA_END_LEN;
103 if (start < str.length()) {
104 end = str.indexOf(CDATA_END, start);
105 } else {
106 return;
107 }
108 }
109 buf.append(str.substring(start));
110 }
111 }
112 }
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121 public static String escapeJsonControlCharacters(final String input) {
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127 if (Strings.isEmpty(input)
128 || (input.indexOf('"') == -1 &&
129 input.indexOf('\\') == -1 &&
130 input.indexOf('/') == -1 &&
131 input.indexOf('\b') == -1 &&
132 input.indexOf('\f') == -1 &&
133 input.indexOf('\n') == -1 &&
134 input.indexOf('\r') == -1 &&
135 input.indexOf('\t') == -1)) {
136 return input;
137 }
138
139 final StringBuilder buf = new StringBuilder(input.length() + 6);
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141 final int len = input.length();
142 for (int i = 0; i < len; i++) {
143 final char ch = input.charAt(i);
144 final String escBs = "\\";
145 switch (ch) {
146 case '"':
147 buf.append(escBs);
148 buf.append(ch);
149 break;
150 case '\\':
151 buf.append(escBs);
152 buf.append(ch);
153 break;
154 case '/':
155 buf.append(escBs);
156 buf.append(ch);
157 break;
158 case '\b':
159 buf.append(escBs);
160 buf.append('b');
161 break;
162 case '\f':
163 buf.append(escBs);
164 buf.append('f');
165 break;
166 case '\n':
167 buf.append(escBs);
168 buf.append('n');
169 break;
170 case '\r':
171 buf.append(escBs);
172 buf.append('r');
173 break;
174 case '\t':
175 buf.append(escBs);
176 buf.append('t');
177 break;
178 default:
179 buf.append(ch);
180 }
181 }
182 return buf.toString();
183 }
184 }