1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
/*
* Copyright (C) 2021 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "restorable_file.h"
#include <string>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <android-base/logging.h>
#include <android-base/stringprintf.h>
namespace {
constexpr char kTmpFileSuffix[] = ".tmp";
constexpr char kBackupFileSuffix[] = ".backup";
std::string GetTmpFilePath(const std::string& path) {
return android::base::StringPrintf("%s%s", path.c_str(), kTmpFileSuffix);
}
std::string GetBackupFilePath(const std::string& path) {
return android::base::StringPrintf("%s%s", path.c_str(), kBackupFileSuffix);
}
void UnlinkPossiblyNonExistingFile(const std::string& path) {
if (unlink(path.c_str()) < 0) {
if (errno != ENOENT && errno != EROFS) { // EROFS reported even if it does not exist.
PLOG(ERROR) << "Cannot unlink: " << path;
}
}
}
// Check if file for the given path exists
bool FileExists(const std::string& path) {
struct stat st;
return ::stat(path.c_str(), &st) == 0;
}
} // namespace
namespace android {
namespace installd {
RestorableFile::RestorableFile() : RestorableFile(-1, "") {}
RestorableFile::RestorableFile(int value, const std::string& path) : unique_file_(value, path) {
// As cleanup is null, this does not make much difference but use unique_file_ only for closing
// tmp file.
unique_file_.DisableCleanup();
}
RestorableFile::~RestorableFile() {
reset();
}
void RestorableFile::reset() {
// need to copy before reset clears it.
std::string path(unique_file_.path());
unique_file_.reset();
if (!path.empty()) {
UnlinkPossiblyNonExistingFile(GetTmpFilePath(path));
}
}
bool RestorableFile::CreateBackupFile() {
if (path().empty() || !FileExists(path())) {
return true;
}
std::string backup = GetBackupFilePath(path());
UnlinkPossiblyNonExistingFile(backup);
if (rename(path().c_str(), backup.c_str()) < 0) {
PLOG(ERROR) << "Cannot rename " << path() << " to " << backup;
return false;
}
return true;
}
bool RestorableFile::CommitWorkFile() {
std::string path(unique_file_.path());
// Keep the path with Commit for debugging purpose.
unique_file_.reset(-1, path);
if (!path.empty()) {
if (rename(GetTmpFilePath(path).c_str(), path.c_str()) < 0) {
PLOG(ERROR) << "Cannot rename " << GetTmpFilePath(path) << " to " << path;
// Remove both files as renaming can fail due to the original file as well.
UnlinkPossiblyNonExistingFile(path);
UnlinkPossiblyNonExistingFile(GetTmpFilePath(path));
return false;
}
}
return true;
}
bool RestorableFile::RestoreBackupFile() {
std::string backup = GetBackupFilePath(path());
if (path().empty() || !FileExists(backup)) {
return true;
}
UnlinkPossiblyNonExistingFile(path());
if (rename(backup.c_str(), path().c_str()) < 0) {
PLOG(ERROR) << "Cannot rename " << backup << " to " << path();
return false;
}
return true;
}
void RestorableFile::RemoveBackupFile() {
UnlinkPossiblyNonExistingFile(GetBackupFilePath(path()));
}
const UniqueFile& RestorableFile::GetUniqueFile() const {
return unique_file_;
}
void RestorableFile::ResetAndRemoveAllFiles() {
std::string path(unique_file_.path());
reset();
RemoveAllFiles(path);
}
RestorableFile RestorableFile::CreateWritableFile(const std::string& path, int permissions) {
std::string tmp_file_path = GetTmpFilePath(path);
// If old tmp file exists, delete it.
UnlinkPossiblyNonExistingFile(tmp_file_path);
int fd = -1;
if (!path.empty()) {
fd = open(tmp_file_path.c_str(), O_RDWR | O_CREAT, permissions);
if (fd < 0) {
PLOG(ERROR) << "Cannot create file: " << tmp_file_path;
}
}
RestorableFile rf(fd, path);
return rf;
}
void RestorableFile::RemoveAllFiles(const std::string& path) {
UnlinkPossiblyNonExistingFile(GetTmpFilePath(path));
UnlinkPossiblyNonExistingFile(GetBackupFilePath(path));
UnlinkPossiblyNonExistingFile(path);
}
} // namespace installd
} // namespace android
|