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1 /*
2  * Copyright (C) 2020 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 #ifndef ANDROID_APEXD_APEXD_ROLLBACK_UTILS_H_
18 #define ANDROID_APEXD_APEXD_ROLLBACK_UTILS_H_
19 
20 #include <filesystem>
21 #include <string>
22 
23 #include <android-base/logging.h>
24 #include <android-base/macros.h>
25 #include <android-base/result.h>
26 #include <android-base/scopeguard.h>
27 #include <logwrap/logwrap.h>
28 #include <selinux/android.h>
29 
30 using android::base::Error;
31 using android::base::Result;
32 
33 namespace android {
34 namespace apex {
35 
36 static constexpr const char* kCpPath = "/system/bin/cp";
37 
38 /**
39  * Copies everything including directories from the "from" path to the "to"
40  * path. Note that this will fail if run before APEXes are mounted, due to a
41  * dependency on runtime.
42  */
copy_directory_recursive(const char * from,const char * to)43 int32_t copy_directory_recursive(const char* from, const char* to) {
44   const char* const argv[] = {
45       kCpPath,
46       "-F", /* delete any existing destination file first
47                       (--remove-destination) */
48       "-p", /* preserve timestamps, ownership, and permissions */
49       "-R", /* recurse into subdirectories (DEST must be a directory) */
50       "-P", /* Do not follow symlinks [default] */
51       "-d", /* don't dereference symlinks */
52       from,
53       to};
54 
55   LOG(DEBUG) << "Copying " << from << " to " << to;
56   return logwrap_fork_execvp(arraysize(argv), argv, nullptr, false, LOG_ALOG,
57                              false, nullptr);
58 }
59 
60 /**
61  * Deletes any files at to_path, and then copies all files and directories
62  * from from_path into to_path. Note that this must be run after APEXes are
63  * mounted.
64  */
ReplaceFiles(const std::string & from_path,const std::string & to_path)65 inline Result<void> ReplaceFiles(const std::string& from_path,
66                                  const std::string& to_path) {
67   namespace fs = std::filesystem;
68 
69   std::error_code error_code;
70   fs::remove_all(to_path, error_code);
71   if (error_code) {
72     return Error() << "Failed to delete existing files at " << to_path << " : "
73                    << error_code.message();
74   }
75 
76   auto deleter = [&] {
77     std::error_code error_code;
78     fs::remove_all(to_path, error_code);
79     if (error_code) {
80       LOG(ERROR) << "Failed to clean up files at " << to_path << " : "
81                  << error_code.message();
82     }
83   };
84   auto scope_guard = android::base::make_scope_guard(deleter);
85 
86   int rc = copy_directory_recursive(from_path.c_str(), to_path.c_str());
87   if (rc != 0) {
88     return Error() << "Failed to copy from [" << from_path << "] to ["
89                    << to_path << "]";
90   }
91   scope_guard.Disable();
92   return {};
93 }
94 
RestoreconPath(const std::string & path)95 inline Result<void> RestoreconPath(const std::string& path) {
96   unsigned int seflags = SELINUX_ANDROID_RESTORECON_RECURSE;
97   if (selinux_android_restorecon(path.c_str(), seflags) < 0) {
98     return Error() << "Failed to restorecon " << path;
99   }
100   return {};
101 }
102 
103 }  // namespace apex
104 }  // namespace android
105 
106 #endif  // ANDROID_APEXD_APEXD_ROLLBACK_UTILS_H_
107