1 /****************************************************************************** 2 * 3 * Copyright (C) 2012 Broadcom Corporation 4 * 5 * Licensed under the Apache License, Version 2.0 (the "License"); 6 * you may not use this file except in compliance with the License. 7 * You may obtain a copy of the License at: 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 ******************************************************************************/ 18 #include "CrcChecksum.h" 19 20 #include <fcntl.h> 21 #include <unistd.h> 22 #include <string> 23 24 #include <android-base/stringprintf.h> 25 #include <base/logging.h> 26 27 using android::base::StringPrintf; 28 29 extern bool nfc_debug_enabled; 30 31 static const unsigned short crctab[256] = { 32 0x0000, 0xc0c1, 0xc181, 0x0140, 0xc301, 0x03c0, 0x0280, 0xc241, 0xc601, 33 0x06c0, 0x0780, 0xc741, 0x0500, 0xc5c1, 0xc481, 0x0440, 0xcc01, 0x0cc0, 34 0x0d80, 0xcd41, 0x0f00, 0xcfc1, 0xce81, 0x0e40, 0x0a00, 0xcac1, 0xcb81, 35 0x0b40, 0xc901, 0x09c0, 0x0880, 0xc841, 0xd801, 0x18c0, 0x1980, 0xd941, 36 0x1b00, 0xdbc1, 0xda81, 0x1a40, 0x1e00, 0xdec1, 0xdf81, 0x1f40, 0xdd01, 37 0x1dc0, 0x1c80, 0xdc41, 0x1400, 0xd4c1, 0xd581, 0x1540, 0xd701, 0x17c0, 38 0x1680, 0xd641, 0xd201, 0x12c0, 0x1380, 0xd341, 0x1100, 0xd1c1, 0xd081, 39 0x1040, 0xf001, 0x30c0, 0x3180, 0xf141, 0x3300, 0xf3c1, 0xf281, 0x3240, 40 0x3600, 0xf6c1, 0xf781, 0x3740, 0xf501, 0x35c0, 0x3480, 0xf441, 0x3c00, 41 0xfcc1, 0xfd81, 0x3d40, 0xff01, 0x3fc0, 0x3e80, 0xfe41, 0xfa01, 0x3ac0, 42 0x3b80, 0xfb41, 0x3900, 0xf9c1, 0xf881, 0x3840, 0x2800, 0xe8c1, 0xe981, 43 0x2940, 0xeb01, 0x2bc0, 0x2a80, 0xea41, 0xee01, 0x2ec0, 0x2f80, 0xef41, 44 0x2d00, 0xedc1, 0xec81, 0x2c40, 0xe401, 0x24c0, 0x2580, 0xe541, 0x2700, 45 0xe7c1, 0xe681, 0x2640, 0x2200, 0xe2c1, 0xe381, 0x2340, 0xe101, 0x21c0, 46 0x2080, 0xe041, 0xa001, 0x60c0, 0x6180, 0xa141, 0x6300, 0xa3c1, 0xa281, 47 0x6240, 0x6600, 0xa6c1, 0xa781, 0x6740, 0xa501, 0x65c0, 0x6480, 0xa441, 48 0x6c00, 0xacc1, 0xad81, 0x6d40, 0xaf01, 0x6fc0, 0x6e80, 0xae41, 0xaa01, 49 0x6ac0, 0x6b80, 0xab41, 0x6900, 0xa9c1, 0xa881, 0x6840, 0x7800, 0xb8c1, 50 0xb981, 0x7940, 0xbb01, 0x7bc0, 0x7a80, 0xba41, 0xbe01, 0x7ec0, 0x7f80, 51 0xbf41, 0x7d00, 0xbdc1, 0xbc81, 0x7c40, 0xb401, 0x74c0, 0x7580, 0xb541, 52 0x7700, 0xb7c1, 0xb681, 0x7640, 0x7200, 0xb2c1, 0xb381, 0x7340, 0xb101, 53 0x71c0, 0x7080, 0xb041, 0x5000, 0x90c1, 0x9181, 0x5140, 0x9301, 0x53c0, 54 0x5280, 0x9241, 0x9601, 0x56c0, 0x5780, 0x9741, 0x5500, 0x95c1, 0x9481, 55 0x5440, 0x9c01, 0x5cc0, 0x5d80, 0x9d41, 0x5f00, 0x9fc1, 0x9e81, 0x5e40, 56 0x5a00, 0x9ac1, 0x9b81, 0x5b40, 0x9901, 0x59c0, 0x5880, 0x9841, 0x8801, 57 0x48c0, 0x4980, 0x8941, 0x4b00, 0x8bc1, 0x8a81, 0x4a40, 0x4e00, 0x8ec1, 58 0x8f81, 0x4f40, 0x8d01, 0x4dc0, 0x4c80, 0x8c41, 0x4400, 0x84c1, 0x8581, 59 0x4540, 0x8701, 0x47c0, 0x4680, 0x8641, 0x8201, 0x42c0, 0x4380, 0x8341, 60 0x4100, 0x81c1, 0x8081, 0x4040, 61 }; 62 63 /******************************************************************************* 64 ** 65 ** Function crcChecksumCompute 66 ** 67 ** Description Compute a checksum on a buffer of data. 68 ** 69 ** Returns 2-byte checksum. 70 ** 71 *******************************************************************************/ 72 unsigned short crcChecksumCompute(const unsigned char* buffer, int bufferLen) { 73 unsigned short crc = 0; 74 const unsigned char* cp = buffer; 75 int cnt = bufferLen; 76 77 while (cnt--) { 78 crc = ((crc >> 8) & 0xff) ^ crctab[(crc & 0xff) ^ *cp++]; 79 } 80 return (crc); 81 } 82 83 /******************************************************************************* 84 ** 85 ** Function crcChecksumVerifyIntegrity 86 ** 87 ** Description Detect any corruption in a file by computing a checksum. 88 ** filename: file name. 89 ** 90 ** Returns True if file is good. 91 ** 92 *******************************************************************************/ 93 bool crcChecksumVerifyIntegrity(const char* filename) { 94 DLOG_IF(INFO, nfc_debug_enabled) 95 << StringPrintf("%s: filename=%s", __func__, filename); 96 bool isGood = false; 97 int fileStream = open(filename, O_RDONLY); 98 if (fileStream >= 0) { 99 unsigned short checksum = 0; 100 std::string data; 101 size_t actualReadCrc = read(fileStream, &checksum, sizeof(checksum)); 102 while (true) { 103 char buffer[1024]; 104 ssize_t actualReadData = read(fileStream, buffer, sizeof(buffer)); 105 if (actualReadData > 0) 106 data.append(buffer, actualReadData); 107 else 108 break; 109 } 110 close(fileStream); 111 if ((actualReadCrc == sizeof(checksum)) && (data.size() > 0)) { 112 DLOG_IF(INFO, nfc_debug_enabled) 113 << StringPrintf("%s: data size=%zu", __func__, data.size()); 114 if (checksum == 115 crcChecksumCompute((const unsigned char*)data.data(), data.size())) 116 isGood = true; 117 else 118 LOG(ERROR) << StringPrintf("%s: checksum mismatch", __func__); 119 } else 120 LOG(ERROR) << StringPrintf("%s: invalid length", __func__); 121 } else 122 isGood = true; // assume file does not exist 123 return isGood; 124 } 125
