1 /*
2 * Logback: the reliable, generic, fast and flexible logging framework.
3 * Copyright (C) 1999-2023, QOS.ch. All rights reserved.
4 *
5 * This program and the accompanying materials are dual-licensed under
6 * either the terms of the Eclipse Public License v1.0 as published by
7 * the Eclipse Foundation
8 *
9 * or (per the licensee's choosing)
10 *
11 * under the terms of the GNU Lesser General Public License version 2.1
12 * as published by the Free Software Foundation.
13 */
14
15 package ch.qos.logback.core.encoder;
16
17 public class JsonEscapeUtil {
18
19 protected final static char[] HEXADECIMALS_TABLE = "0123456789ABCDEF".toCharArray();
20
21 static final int ESCAPE_CODES_COUNT = 32;
22
23 static final String[] ESCAPE_CODES = new String[ESCAPE_CODES_COUNT];
24
25 // From RFC-8259 page 5
26
27 // %x22 / ; " quotation mark U+0022
28 // %x5C / ; \ reverse solidus U+005C
29 // %x2F / ; / solidus U+002F
30
31 // %x62 / ; b backspace U+0008
32 // %x74 / ; t tab U+0009
33 // %x6E / ; n line feed U+000A
34 // %x66 / ; f form feed U+000C
35 // %x72 / ; r carriage return U+000D
36
37 static {
38 for (char c = 0; c < ESCAPE_CODES_COUNT; c++) {
39
40 switch (c) {
41 case 0x08:
42 ESCAPE_CODES[c] = "\\b";
43 break;
44 case 0x09:
45 ESCAPE_CODES[c] = "\\t";
46 break;
47 case 0x0A:
48 ESCAPE_CODES[c] = "\\n";
49 break;
50 case 0x0C:
51 ESCAPE_CODES[c] = "\\f";
52 break;
53 case 0x0D:
54 ESCAPE_CODES[c] = "\\r";
55 break;
56 default:
57 ESCAPE_CODES[c] = _computeEscapeCodeBelowASCII32(c);
58 }
59 }
60 }
61
62 // this method should not be called by methods except the static initializer
63 private static String _computeEscapeCodeBelowASCII32(char c) {
64 if (c > 32) {
65 throw new IllegalArgumentException("input must be less than 32");
66 }
67
68 StringBuilder sb = new StringBuilder(6);
69 sb.append("\\u00");
70
71 int highPart = c >> 4;
72 sb.append(HEXADECIMALS_TABLE[highPart]);
73
74 int lowPart = c & 0x0F;
75 sb.append(HEXADECIMALS_TABLE[lowPart]);
76
77 return sb.toString();
78 }
79
80 // %x22 / ; " quotation mark U+0022
81 // %x5C / ; \ reverse solidus U+005C
82
83 static String getObligatoryEscapeCode(char c) {
84 if (c < 32)
85 return ESCAPE_CODES[c];
86 if (c == 0x22)
87 return "\\\"";
88 if (c == 0x5C)
89 return "\\/";
90
91 return null;
92 }
93
94 static public String jsonEscapeString(String input) {
95 int length = input.length();
96 int lenthWithLeeway = (int) (length * 1.1);
97
98 StringBuilder sb = new StringBuilder(lenthWithLeeway);
99 for (int i = 0; i < length; i++) {
100 final char c = input.charAt(i);
101 String escaped = getObligatoryEscapeCode(c);
102 if (escaped == null)
103 sb.append(c);
104 else {
105 sb.append(escaped);
106 }
107 }
108
109 return sb.toString();
110 }
111
112 }