code.grnet.gr Git - pithos-macos/blob - pithos-macos/FileMD5Hash.c

   1 /*
   2  *  FileMD5Hash.c
   3  *  FileMD5Hash
   4  *
   5  *  Copyright © 2010 Joel Lopes Da Silva. All rights reserved.
   6  *
   7  *  Licensed under the Apache License, Version 2.0 (the "License");
   8  *  you may not use this file except in compliance with the License.
   9  *  You may obtain a copy of the License at
  10  *
  11  *        http://www.apache.org/licenses/LICENSE-2.0
  12  *
  13  *  Unless required by applicable law or agreed to in writing, software
  14  *  distributed under the License is distributed on an "AS IS" BASIS,
  15  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  16  *  See the License for the specific language governing permissions and
  17  *  limitations under the License.
  18  *
  19  */
  20
  21 //---------------------------------------------------------
  22 // Includes
  23 //---------------------------------------------------------
  24
  25 // Header file
  26 #include "FileMD5Hash.h"
  27
  28 // Standard library
  29 #include <stdint.h>
  30 #include <stdio.h>
  31
  32 // Core Foundation
  33 #include <CoreFoundation/CoreFoundation.h>
  34
  35 // Cryptography
  36 #include <CommonCrypto/CommonDigest.h>
  37
  38
  39 //---------------------------------------------------------
  40 // Function definition
  41 //---------------------------------------------------------
  42
  43 CFStringRef FileMD5HashCreateWithPath(CFStringRef filePath,
  44                                       size_t chunkSizeForReadingData) {
  45
  46     // Declare needed variables
  47     CFStringRef result = NULL;
  48     CFReadStreamRef readStream = NULL;
  49
  50     // Get the file URL
  51     CFURLRef fileURL =
  52     CFURLCreateWithFileSystemPath(kCFAllocatorDefault,
  53                                   (CFStringRef)filePath,
  54                                   kCFURLPOSIXPathStyle,
  55                                   (Boolean)false);
  56     if (!fileURL) goto done;
  57
  58     // Create and open the read stream
  59     readStream = CFReadStreamCreateWithFile(kCFAllocatorDefault,
  60                                             (CFURLRef)fileURL);
  61     if (!readStream) goto done;
  62     bool didSucceed = (bool)CFReadStreamOpen(readStream);
  63     if (!didSucceed) goto done;
  64
  65     // Initialize the hash object
  66     CC_MD5_CTX hashObject;
  67     CC_MD5_Init(&hashObject);
  68
  69     // Make sure chunkSizeForReadingData is valid
  70     if (!chunkSizeForReadingData) {
  71         chunkSizeForReadingData = FileHashDefaultChunkSizeForReadingData;
  72     }
  73
  74     // Feed the data to the hash object
  75     bool hasMoreData = true;
  76     while (hasMoreData) {
  77         uint8_t buffer[chunkSizeForReadingData];
  78         CFIndex readBytesCount = CFReadStreamRead(readStream,
  79                                                   (UInt8 *)buffer,
  80                                                   (CFIndex)sizeof(buffer));
  81         if (readBytesCount == -1) break;
  82         if (readBytesCount == 0) {
  83             hasMoreData = false;
  84             continue;
  85         }
  86         CC_MD5_Update(&hashObject,
  87                       (const void *)buffer,
  88                       (CC_LONG)readBytesCount);
  89     }
  90
  91     // Check if the read operation succeeded
  92     didSucceed = !hasMoreData;
  93
  94     // Compute the hash digest
  95     unsigned char digest[CC_MD5_DIGEST_LENGTH];
  96     CC_MD5_Final(digest, &hashObject);
  97
  98     // Abort if the read operation failed
  99     if (!didSucceed) goto done;
 100
 101     // Compute the string result
 102     char hash[2 * sizeof(digest) + 1];
 103     for (size_t i = 0; i < sizeof(digest); ++i) {
 104         snprintf(hash + (2 * i), 3, "%02x", (int)(digest[i]));
 105     }
 106     result = CFStringCreateWithCString(kCFAllocatorDefault,
 107                                        (const char *)hash,
 108                                        kCFStringEncodingUTF8);
 109
 110 done:
 111
 112     if (readStream) {
 113         CFReadStreamClose(readStream);
 114         CFRelease(readStream);
 115     }
 116     if (fileURL) {
 117         CFRelease(fileURL);
 118     }
 119     return result;
 120 }