xapian-core/backends/uuids.cc

   1 /** @file uuids.cc
   2  * @brief Class for handling UUIDs
   3  */
   4 /* Copyright (C) 2008 Lemur Consulting Ltd
   5  * Copyright (C) 2013,2015,2016,2017,2018 Olly Betts
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  20  */
  21
  22 #include <config.h>
  23
  24 #include "uuids.h"
  25
  26 #include "xapian/error.h"
  27
  28 #include <cstring>
  29 #include "stringutils.h"
  30
  31 #include <sys/types.h>
  32 #include "safeerrno.h"
  33 #include "safefcntl.h"
  34 #include "safeunistd.h"
  35
  36 #ifdef USE_PROC_FOR_UUID
  37 # include "safesysstat.h"
  38 #elif defined HAVE_UUID_UUID_H
  39 # include <exception>
  40 # include <uuid/uuid.h>
  41 #elif defined HAVE_UUID_H
  42 // UUID API on FreeBSD, NetBSD and AIX.
  43 # include <exception>
  44 # include <uuid.h>
  45 #elif defined USE_WIN32_UUID_API
  46 # include "safewindows.h"
  47 # include <rpc.h>
  48 # ifdef __WIN32__
  49 #  include "safewinsock2.h" // For htonl() and htons().
  50 # else
  51 // Cygwin:
  52 #  include <arpa/inet.h> // For htonl() and htons().
  53 # endif
  54 #endif
  55
  56 using namespace std;
  57
  58 /// Bit-mask to determine where to put hyphens in the string representation.
  59 static constexpr unsigned UUID_GAP_MASK = 0x2a8;
  60
  61 void
  62 Uuid::generate()
  63 {
  64 #ifdef USE_PROC_FOR_UUID
  65     char buf[STRING_SIZE];
  66     int fd = open("/proc/sys/kernel/random/uuid", O_RDONLY);
  67     if (rare(fd == -1)) {
  68         throw Xapian::DatabaseCreateError("Opening UUID generator failed", errno);
  69     }
  70     bool failed = (read(fd, buf, STRING_SIZE) != STRING_SIZE);
  71     close(fd);
  72     if (failed) {
  73         throw Xapian::DatabaseCreateError("Generating UUID failed");
  74     }
  75     parse(buf);
  76 #elif defined HAVE_UUID_UUID_H
  77     uuid_t uu;
  78     uuid_generate(uu);
  79     memcpy(uuid_data, &uu, BINARY_SIZE);
  80 #elif defined HAVE_UUID_H
  81     uuid_t uu;
  82     uint32_t status;
  83     uuid_create(uu, &status);
  84     if (status != uuid_s_ok) {
  85         // Can only be uuid_s_no_memory it seems.
  86         throw std::bad_alloc();
  87     }
  88     memcpy(uuid_data, &uu, BINARY_SIZE);
  89 #elif defined USE_WIN32_UUID_API
  90     UUID uuid;
  91     if (rare(UuidCreate(&uuid) != RPC_S_OK)) {
  92         // Throw a DatabaseCreateError, since we can't make a UUID.  The
  93         // windows API documentation is a bit unclear about the situations in
  94         // which this can happen.
  95         throw Xapian::DatabaseCreateError("Cannot create UUID");
  96     }
  97     uuid.Data1 = htonl(uuid.Data1);
  98     uuid.Data2 = htons(uuid.Data2);
  99     uuid.Data3 = htons(uuid.Data3);
 100     memcpy(uuid_data, &uuid, BINARY_SIZE);
 101 #else
 102 # error Do not know how to generate UUIDs
 103 #endif
 104 }
 105
 106 void
 107 Uuid::parse(const char* in)
 108 {
 109     for (unsigned i = 0; i != BINARY_SIZE; ++i) {
 110         uuid_data[i] = hex_digit(in[0]) << 4 | hex_digit(in[1]);
 111         in += ((UUID_GAP_MASK >> i) & 1) | 2;
 112     }
 113 }
 114
 115 string
 116 Uuid::to_string() const
 117 {
 118     string result;
 119     result.reserve(STRING_SIZE);
 120     for (unsigned i = 0; i != BINARY_SIZE; ++i) {
 121         unsigned char ch = uuid_data[i];
 122         result += "0123456789abcdef"[ch >> 4];
 123         result += "0123456789abcdef"[ch & 0x0f];
 124         if ((UUID_GAP_MASK >> i) & 1)
 125            result += '-';
 126     }
 127     return result;
 128 }