1 /*
2  * Copyright (C) 2011 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.android.tradefed.util;
18 
19 import java.util.ArrayList;
20 import java.util.Arrays;
21 import java.util.List;
22 
23 /**
24  * Utility class for escaping strings for specific formats.
25  * Include methods to escape strings that are being passed to the Android Shell.
26  */
27 public class StringEscapeUtils {
28 
29     /**
30      * Escapes a {@link String} for use in an Android shell command.
31      *
32      * @param str the {@link String} to escape
33      * @return the Android shell escaped {@link String}
34      */
escapeShell(String str)35     public static String escapeShell(String str) {
36         if (str == null) {
37             return null;
38         }
39         StringBuilder out = new StringBuilder();
40         for (int i = 0; i < str.length(); ++i) {
41             char ch = str.charAt(i);
42             // TODO: add other characters as needed.
43             switch (ch) {
44                 case '$':
45                     out.append("\\$");
46                     break;
47                 case '\\':
48                     out.append("\\\\");
49                     break;
50                 case '>':
51                     out.append("\\>");
52                     break;
53                 case '<':
54                     out.append("\\<");
55                     break;
56                 case '|':
57                     out.append("\\|");
58                     break;
59                 default:
60                     out.append(ch);
61                     break;
62             }
63         }
64         return out.toString();
65     }
66 
67     /**
68      * Converts the provided parameters via options to command line args to sub process
69      *
70      * <p>This method will do a simplistic generic unescape for each parameter in the list. It
71      * replaces \[char] with [char]. For example, \" is converted to ". This allows string with
72      * escaped double quotes to stay as a string after being parsed by QuotationAwareTokenizer.
73      * Without this QuotationAwareTokenizer will break the string into sections if it has space in
74      * it.
75      *
76      * @param params parameters received via options
77      * @return list of string representing command line args
78      */
paramsToArgs(List<String> params)79     public static List<String> paramsToArgs(List<String> params) {
80         List<String> result = new ArrayList<>();
81         for (String param : params) {
82             // doing a simplistic generic unescape here: \<char> is replaced with <char>; note that
83             // this may lead to incorrect results such as \n -> n, or \t -> t, but it's unclear why
84             // a command line param would have \t anyways
85             param = param.replaceAll("\\\\(.)", "$1");
86             String[] args = QuotationAwareTokenizer.tokenizeLine(param, /* Logging */ false);
87             if (args.length != 0) {
88                 result.addAll(Arrays.asList(args));
89             }
90         }
91         return result;
92     }
93 }
94