xapian-applications/omega/md5wrap.cc

   1 /* md5wrap.cc: wrapper functions to allow easy use of MD5 from C++.
   2  *
   3  * Copyright (C) 2006,2010,2012,2013,2015 Olly Betts
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License as published by
   7  * the Free Software Foundation; either version 2 of the License, or
   8  * (at your option) any later version.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  18  */
  19
  20 #include <config.h>
  21
  22 #ifdef HAVE_POSIX_FADVISE
  23 # ifdef __linux__
  24 #  define _POSIX_C_SOURCE 200112L // for posix_fadvise from fcntl.h
  25 #  define _DEFAULT_SOURCE 1 // Needed to get lstat() for glibc >= 2.20
  26 #  define _BSD_SOURCE 1 // Needed to get lstat() for glibc < 2.20
  27 # endif
  28 #endif
  29
  30 #include <string>
  31
  32 #include "safefcntl.h"
  33 #include "safeerrno.h"
  34 #include "safeunistd.h"
  35
  36 #include "md5.h"
  37 #include "md5wrap.h"
  38
  39 using namespace std;
  40
  41 bool
  42 md5_file(const string &file_name, string &md5, bool try_noatime)
  43 {
  44     mode_t mode = O_RDONLY;
  45 #if defined O_NOATIME && O_NOATIME != 0
  46     if (try_noatime) mode |= O_NOATIME;
  47 #else
  48     (void)try_noatime;
  49 #endif
  50
  51     int fd = open(file_name.c_str(), mode);
  52 #if defined O_NOATIME && O_NOATIME != 0
  53     if (fd < 0 && (mode & O_NOATIME)) {
  54         mode &= ~O_NOATIME;
  55         fd = open(file_name.c_str(), mode);
  56     }
  57 #endif
  58     if (fd < 0) return false;
  59
  60 #ifdef HAVE_POSIX_FADVISE
  61     posix_fadvise(fd, 0, 0, POSIX_FADV_NOREUSE); // or POSIX_FADV_SEQUENTIAL
  62 #endif
  63
  64     MD5Context md5_ctx;
  65     MD5Init(&md5_ctx);
  66
  67     unsigned char blk[4096];
  68
  69     while (true) {
  70         int c = read(fd, blk, sizeof(blk));
  71         if (c == 0) break;
  72         if (c < 0) {
  73             if (errno == EINTR) continue;
  74             close(fd);
  75             return false;
  76         }
  77         MD5Update(&md5_ctx, blk, c);
  78     }
  79
  80 #ifdef HAVE_POSIX_FADVISE
  81     posix_fadvise(fd, 0, 0, POSIX_FADV_DONTNEED);
  82 #endif
  83
  84     close(fd);
  85
  86     MD5Final(blk, &md5_ctx);
  87     md5.assign(reinterpret_cast<const char *>(blk), 16);
  88
  89     return true;
  90 }
  91
  92 void
  93 md5_block(const char * p, size_t len, string &md5)
  94 {
  95     unsigned char blk[16];
  96     MD5Context md5_ctx;
  97
  98     MD5Init(&md5_ctx);
  99     MD5Update(&md5_ctx, reinterpret_cast<const unsigned char *>(p), len);
 100     MD5Final(blk, &md5_ctx);
 101     md5.assign(reinterpret_cast<const char *>(blk), 16);
 102 }