| 1 | /* |
| 2 | * SPDX-License-Identifier: LGPL-2.1-only |
| 3 | * |
| 4 | * Copyright (C) 2017 EfficiOS Inc. |
| 5 | * Copyright (C) 2017 Philippe Proulx <pproulx@efficios.com> |
| 6 | */ |
| 7 | |
| 8 | package org.lttng.ust.agent; |
| 9 | |
| 10 | import java.util.regex.Pattern; |
| 11 | |
| 12 | /** |
| 13 | * Class encapsulating an event name from the session daemon, and its |
| 14 | * corresponding {@link Pattern}. This allows referring back to the original |
| 15 | * event name, for example when we receive a disable command. |
| 16 | * |
| 17 | * @author Philippe Proulx |
| 18 | * @author Alexandre Montplaisir |
| 19 | */ |
| 20 | class EventNamePattern { |
| 21 | |
| 22 | private final String originalEventName; |
| 23 | |
| 24 | /* |
| 25 | * Note that two Patterns coming from the exact same String will not be |
| 26 | * equals()! As such, it would be confusing to make the pattern part of this |
| 27 | * class's equals/hashCode |
| 28 | */ |
| 29 | private final transient Pattern pattern; |
| 30 | |
| 31 | public EventNamePattern(String eventName) { |
| 32 | if (eventName == null) { |
| 33 | throw new IllegalArgumentException(); |
| 34 | } |
| 35 | |
| 36 | originalEventName = eventName; |
| 37 | pattern = patternFromEventName(eventName); |
| 38 | } |
| 39 | |
| 40 | public String getEventName() { |
| 41 | return originalEventName; |
| 42 | } |
| 43 | |
| 44 | public Pattern getPattern() { |
| 45 | return pattern; |
| 46 | } |
| 47 | |
| 48 | @Override |
| 49 | public int hashCode() { |
| 50 | final int prime = 31; |
| 51 | int result = 1; |
| 52 | result = prime * result + originalEventName.hashCode(); |
| 53 | return result; |
| 54 | } |
| 55 | |
| 56 | @Override |
| 57 | public boolean equals(Object obj) { |
| 58 | if (this == obj) { |
| 59 | return true; |
| 60 | } |
| 61 | if (obj == null) { |
| 62 | return false; |
| 63 | } |
| 64 | if (getClass() != obj.getClass()) { |
| 65 | return false; |
| 66 | } |
| 67 | EventNamePattern other = (EventNamePattern) obj; |
| 68 | if (!originalEventName.equals(other.originalEventName)) { |
| 69 | return false; |
| 70 | } |
| 71 | return true; |
| 72 | } |
| 73 | |
| 74 | private static Pattern patternFromEventName(String eventName) { |
| 75 | /* |
| 76 | * The situation here is that `\*` means a literal `*` in the event |
| 77 | * name, and `*` is a wildcard star. We check the event name one |
| 78 | * character at a time and create a list of tokens to be converter to |
| 79 | * partial patterns. |
| 80 | */ |
| 81 | StringBuilder bigBuilder = new StringBuilder("^"); |
| 82 | StringBuilder smallBuilder = new StringBuilder(); |
| 83 | |
| 84 | for (int i = 0; i < eventName.length(); i++) { |
| 85 | char c = eventName.charAt(i); |
| 86 | |
| 87 | switch (c) { |
| 88 | case '*': |
| 89 | /* Add current quoted builder's string if not empty. */ |
| 90 | if (smallBuilder.length() > 0) { |
| 91 | bigBuilder.append(Pattern.quote(smallBuilder.toString())); |
| 92 | smallBuilder.setLength(0); |
| 93 | } |
| 94 | |
| 95 | /* Append the equivalent regex which is `.*`. */ |
| 96 | bigBuilder.append(".*"); |
| 97 | continue; |
| 98 | |
| 99 | case '\\': |
| 100 | /* We only escape `*` and `\` here. */ |
| 101 | if (i < (eventName.length() - 1)) { |
| 102 | char nextChar = eventName.charAt(i + 1); |
| 103 | |
| 104 | if (nextChar == '*' || nextChar == '\\') { |
| 105 | smallBuilder.append(nextChar); |
| 106 | } else { |
| 107 | smallBuilder.append(c); |
| 108 | smallBuilder.append(nextChar); |
| 109 | } |
| 110 | |
| 111 | i++; |
| 112 | continue; |
| 113 | } |
| 114 | break; |
| 115 | |
| 116 | default: |
| 117 | break; |
| 118 | } |
| 119 | |
| 120 | smallBuilder.append(c); |
| 121 | } |
| 122 | |
| 123 | /* Add current quoted builder's string if not empty. */ |
| 124 | if (smallBuilder.length() > 0) { |
| 125 | bigBuilder.append(Pattern.quote(smallBuilder.toString())); |
| 126 | } |
| 127 | |
| 128 | bigBuilder.append("$"); |
| 129 | |
| 130 | return Pattern.compile(bigBuilder.toString()); |
| 131 | } |
| 132 | } |