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 <arpa/inet.h> // For htonl() and htons().
  44 # include <exception>
  45 # include <uuid.h>
  46 #elif defined USE_WIN32_UUID_API
  47 # include "safewindows.h"
  48 # include <rpc.h>
  49 # ifdef __WIN32__
  50 #  include "safewinsock2.h" // For htonl() and htons().
  51 # else
  52 // Cygwin:
  53 #  include <arpa/inet.h> // For htonl() and htons().
  54 # endif
  55 #endif
  56
  57 using namespace std;
  58
  59 /// Bit-mask to determine where to put hyphens in the string representation.
  60 static constexpr unsigned UUID_GAP_MASK = 0x2a8;
  61
  62 void
  63 Uuid::generate()
  64 {
  65 #ifdef USE_PROC_FOR_UUID
  66     char buf[STRING_SIZE];
  67     int fd = open("/proc/sys/kernel/random/uuid", O_RDONLY);
  68     if (rare(fd == -1)) {
  69         throw Xapian::DatabaseCreateError("Opening UUID generator failed", errno);
  70     }
  71     bool failed = (read(fd, buf, STRING_SIZE) != STRING_SIZE);
  72     close(fd);
  73     if (failed) {
  74         throw Xapian::DatabaseCreateError("Generating UUID failed");
  75     }
  76     parse(buf);
  77 #elif defined HAVE_UUID_UUID_H
  78     uuid_t uu;
  79     uuid_generate(uu);
  80     memcpy(uuid_data, &uu, BINARY_SIZE);
  81 #elif defined HAVE_UUID_H
  82     uuid_t uu;
  83     uint32_t status;
  84     uuid_create(&uu, &status);
  85     if (status != uuid_s_ok) {
  86         // Can only be uuid_s_no_memory it seems.
  87         throw std::bad_alloc();
  88     }
  89     uu.time_low = htonl(uu.time_low);
  90     uu.time_mid = htons(uu.time_mid);
  91     uu.time_hi_and_version = htons(uu.time_hi_and_version);
  92     memcpy(uuid_data, &uu, BINARY_SIZE);
  93 #elif defined USE_WIN32_UUID_API
  94     UUID uuid;
  95     if (rare(UuidCreate(&uuid) != RPC_S_OK)) {
  96         // Throw a DatabaseCreateError, since we can't make a UUID.  The
  97         // windows API documentation is a bit unclear about the situations in
  98         // which this can happen.
  99         throw Xapian::DatabaseCreateError("Cannot create UUID");
 100     }
 101     uuid.Data1 = htonl(uuid.Data1);
 102     uuid.Data2 = htons(uuid.Data2);
 103     uuid.Data3 = htons(uuid.Data3);
 104     memcpy(uuid_data, &uuid, BINARY_SIZE);
 105 #else
 106 # error Do not know how to generate UUIDs
 107 #endif
 108 }
 109
 110 void
 111 Uuid::parse(const char* in)
 112 {
 113     for (unsigned i = 0; i != BINARY_SIZE; ++i) {
 114         uuid_data[i] = hex_digit(in[0]) << 4 | hex_digit(in[1]);
 115         in += ((UUID_GAP_MASK >> i) & 1) | 2;
 116     }
 117 }
 118
 119 string
 120 Uuid::to_string() const
 121 {
 122     string result;
 123     result.reserve(STRING_SIZE);
 124     for (unsigned i = 0; i != BINARY_SIZE; ++i) {
 125         unsigned char ch = uuid_data[i];
 126         result += "0123456789abcdef"[ch >> 4];
 127         result += "0123456789abcdef"[ch & 0x0f];
 128         if ((UUID_GAP_MASK >> i) & 1)
 129            result += '-';
 130     }
 131     return result;
 132 }