Stan Iliev | 9e7cd07 | 2017-10-09 15:56:10 -0400 | [diff] [blame] | 1 | /* |
| 2 | ** Copyright 2017, 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 | #include "FileBlobCache.h" |
| 18 | |
Dan Albert | cbf81da | 2018-01-05 14:24:09 -0800 | [diff] [blame] | 19 | #include <errno.h> |
Tom Cherry | 3387cab | 2020-04-13 11:04:01 -0700 | [diff] [blame] | 20 | #include <fcntl.h> |
Stan Iliev | 9e7cd07 | 2017-10-09 15:56:10 -0400 | [diff] [blame] | 21 | #include <inttypes.h> |
Stan Iliev | 9e7cd07 | 2017-10-09 15:56:10 -0400 | [diff] [blame] | 22 | #include <sys/mman.h> |
| 23 | #include <sys/stat.h> |
Tom Cherry | 28ac3b9 | 2020-04-13 15:19:23 -0700 | [diff] [blame] | 24 | #include <unistd.h> |
Stan Iliev | 9e7cd07 | 2017-10-09 15:56:10 -0400 | [diff] [blame] | 25 | |
Tom Cherry | 3387cab | 2020-04-13 11:04:01 -0700 | [diff] [blame] | 26 | #include <log/log.h> |
Stan Iliev | 9e7cd07 | 2017-10-09 15:56:10 -0400 | [diff] [blame] | 27 | |
| 28 | // Cache file header |
| 29 | static const char* cacheFileMagic = "EGL$"; |
| 30 | static const size_t cacheFileHeaderSize = 8; |
| 31 | |
| 32 | namespace android { |
| 33 | |
| 34 | static uint32_t crc32c(const uint8_t* buf, size_t len) { |
| 35 | const uint32_t polyBits = 0x82F63B78; |
| 36 | uint32_t r = 0; |
| 37 | for (size_t i = 0; i < len; i++) { |
| 38 | r ^= buf[i]; |
| 39 | for (int j = 0; j < 8; j++) { |
| 40 | if (r & 1) { |
| 41 | r = (r >> 1) ^ polyBits; |
| 42 | } else { |
| 43 | r >>= 1; |
| 44 | } |
| 45 | } |
| 46 | } |
| 47 | return r; |
| 48 | } |
| 49 | |
| 50 | FileBlobCache::FileBlobCache(size_t maxKeySize, size_t maxValueSize, size_t maxTotalSize, |
| 51 | const std::string& filename) |
| 52 | : BlobCache(maxKeySize, maxValueSize, maxTotalSize) |
| 53 | , mFilename(filename) { |
| 54 | if (mFilename.length() > 0) { |
| 55 | size_t headerSize = cacheFileHeaderSize; |
| 56 | |
| 57 | int fd = open(mFilename.c_str(), O_RDONLY, 0); |
| 58 | if (fd == -1) { |
| 59 | if (errno != ENOENT) { |
| 60 | ALOGE("error opening cache file %s: %s (%d)", mFilename.c_str(), |
| 61 | strerror(errno), errno); |
| 62 | } |
| 63 | return; |
| 64 | } |
| 65 | |
| 66 | struct stat statBuf; |
| 67 | if (fstat(fd, &statBuf) == -1) { |
| 68 | ALOGE("error stat'ing cache file: %s (%d)", strerror(errno), errno); |
| 69 | close(fd); |
| 70 | return; |
| 71 | } |
| 72 | |
Yiwei Zhang | 26169cd | 2020-07-28 15:46:12 -0700 | [diff] [blame] | 73 | // Check the size before trying to mmap it. |
Stan Iliev | 9e7cd07 | 2017-10-09 15:56:10 -0400 | [diff] [blame] | 74 | size_t fileSize = statBuf.st_size; |
| 75 | if (fileSize > mMaxTotalSize * 2) { |
| 76 | ALOGE("cache file is too large: %#" PRIx64, |
| 77 | static_cast<off64_t>(statBuf.st_size)); |
| 78 | close(fd); |
| 79 | return; |
| 80 | } |
| 81 | |
Yi Kong | 48a6cd2 | 2018-07-18 10:07:09 -0700 | [diff] [blame] | 82 | uint8_t* buf = reinterpret_cast<uint8_t*>(mmap(nullptr, fileSize, |
Stan Iliev | 9e7cd07 | 2017-10-09 15:56:10 -0400 | [diff] [blame] | 83 | PROT_READ, MAP_PRIVATE, fd, 0)); |
| 84 | if (buf == MAP_FAILED) { |
| 85 | ALOGE("error mmaping cache file: %s (%d)", strerror(errno), |
| 86 | errno); |
| 87 | close(fd); |
| 88 | return; |
| 89 | } |
| 90 | |
| 91 | // Check the file magic and CRC |
| 92 | size_t cacheSize = fileSize - headerSize; |
| 93 | if (memcmp(buf, cacheFileMagic, 4) != 0) { |
| 94 | ALOGE("cache file has bad mojo"); |
| 95 | close(fd); |
| 96 | return; |
| 97 | } |
| 98 | uint32_t* crc = reinterpret_cast<uint32_t*>(buf + 4); |
| 99 | if (crc32c(buf + headerSize, cacheSize) != *crc) { |
| 100 | ALOGE("cache file failed CRC check"); |
| 101 | close(fd); |
| 102 | return; |
| 103 | } |
| 104 | |
| 105 | int err = unflatten(buf + headerSize, cacheSize); |
| 106 | if (err < 0) { |
| 107 | ALOGE("error reading cache contents: %s (%d)", strerror(-err), |
| 108 | -err); |
| 109 | munmap(buf, fileSize); |
| 110 | close(fd); |
| 111 | return; |
| 112 | } |
| 113 | |
| 114 | munmap(buf, fileSize); |
| 115 | close(fd); |
| 116 | } |
| 117 | } |
| 118 | |
| 119 | void FileBlobCache::writeToFile() { |
| 120 | if (mFilename.length() > 0) { |
| 121 | size_t cacheSize = getFlattenedSize(); |
| 122 | size_t headerSize = cacheFileHeaderSize; |
| 123 | const char* fname = mFilename.c_str(); |
| 124 | |
| 125 | // Try to create the file with no permissions so we can write it |
| 126 | // without anyone trying to read it. |
| 127 | int fd = open(fname, O_CREAT | O_EXCL | O_RDWR, 0); |
| 128 | if (fd == -1) { |
| 129 | if (errno == EEXIST) { |
| 130 | // The file exists, delete it and try again. |
| 131 | if (unlink(fname) == -1) { |
| 132 | // No point in retrying if the unlink failed. |
| 133 | ALOGE("error unlinking cache file %s: %s (%d)", fname, |
| 134 | strerror(errno), errno); |
| 135 | return; |
| 136 | } |
| 137 | // Retry now that we've unlinked the file. |
| 138 | fd = open(fname, O_CREAT | O_EXCL | O_RDWR, 0); |
| 139 | } |
| 140 | if (fd == -1) { |
| 141 | ALOGE("error creating cache file %s: %s (%d)", fname, |
| 142 | strerror(errno), errno); |
| 143 | return; |
| 144 | } |
| 145 | } |
| 146 | |
| 147 | size_t fileSize = headerSize + cacheSize; |
| 148 | |
| 149 | uint8_t* buf = new uint8_t [fileSize]; |
| 150 | if (!buf) { |
| 151 | ALOGE("error allocating buffer for cache contents: %s (%d)", |
| 152 | strerror(errno), errno); |
| 153 | close(fd); |
| 154 | unlink(fname); |
| 155 | return; |
| 156 | } |
| 157 | |
| 158 | int err = flatten(buf + headerSize, cacheSize); |
| 159 | if (err < 0) { |
| 160 | ALOGE("error writing cache contents: %s (%d)", strerror(-err), |
| 161 | -err); |
| 162 | delete [] buf; |
| 163 | close(fd); |
| 164 | unlink(fname); |
| 165 | return; |
| 166 | } |
| 167 | |
| 168 | // Write the file magic and CRC |
| 169 | memcpy(buf, cacheFileMagic, 4); |
| 170 | uint32_t* crc = reinterpret_cast<uint32_t*>(buf + 4); |
| 171 | *crc = crc32c(buf + headerSize, cacheSize); |
| 172 | |
| 173 | if (write(fd, buf, fileSize) == -1) { |
| 174 | ALOGE("error writing cache file: %s (%d)", strerror(errno), |
| 175 | errno); |
| 176 | delete [] buf; |
| 177 | close(fd); |
| 178 | unlink(fname); |
| 179 | return; |
| 180 | } |
| 181 | |
| 182 | delete [] buf; |
| 183 | fchmod(fd, S_IRUSR); |
| 184 | close(fd); |
| 185 | } |
| 186 | } |
| 187 | |
Dan Albert | cbf81da | 2018-01-05 14:24:09 -0800 | [diff] [blame] | 188 | } |