xapian-core/net/length.cc

   1 /** @file length.cc
   2  * @brief length encoded as a string
   3  */
   4 /* Copyright (C) 2006,2007,2008,2009,2010,2011,2012,2015 Olly Betts
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  19  */
  20
  21 #include <config.h>
  22
  23 #include "length.h"
  24
  25 #ifndef XAPIAN_UNITTEST
  26
  27 #include "xapian/error.h"
  28
  29 [[noreturn]]
  30 static void
  31 throw_network_error(const char * msg)
  32 {
  33     throw Xapian::NetworkError(msg);
  34 }
  35
  36 #else
  37
  38 class Xapian_NetworkError {
  39     const char * msg;
  40
  41   public:
  42     explicit Xapian_NetworkError(const char * msg_) : msg(msg_) { }
  43
  44     const char * get_description() const { return msg; }
  45 };
  46
  47 [[noreturn]]
  48 static void
  49 throw_network_error(const char * msg)
  50 {
  51     throw Xapian_NetworkError(msg);
  52 }
  53
  54 #endif
  55
  56 template<typename T>
  57 inline void
  58 decode_length_(const char ** p, const char *end, T & out)
  59 {
  60     if (*p == end) {
  61         throw_network_error("Bad encoded length: no data");
  62     }
  63
  64     T len = static_cast<unsigned char>(*(*p)++);
  65     if (len == 0xff) {
  66         len = 0;
  67         unsigned char ch;
  68         unsigned shift = 0;
  69         do {
  70             if (*p == end || shift > (sizeof(T) * 8 / 7 * 7))
  71                 throw_network_error("Bad encoded length: insufficient data");
  72             ch = *(*p)++;
  73             len |= T(ch & 0x7f) << shift;
  74             shift += 7;
  75         } while ((ch & 0x80) == 0);
  76         len += 255;
  77     }
  78     out = len;
  79 }
  80
  81 template<typename T>
  82 inline void
  83 decode_length_and_check_(const char ** p, const char *end, T & out)
  84 {
  85     decode_length(p, end, out);
  86     if (out > T(end - *p)) {
  87         throw_network_error("Bad encoded length: length greater than data");
  88     }
  89 }
  90
  91 void
  92 decode_length(const char ** p, const char *end, unsigned & out)
  93 {
  94     decode_length_(p, end, out);
  95 }
  96
  97 void
  98 decode_length(const char ** p, const char *end, unsigned long & out)
  99 {
 100     decode_length_(p, end, out);
 101 }
 102
 103 void
 104 decode_length(const char ** p, const char *end, unsigned long long & out)
 105 {
 106     decode_length_(p, end, out);
 107 }
 108
 109 void
 110 decode_length_and_check(const char ** p, const char *end, unsigned & out)
 111 {
 112     decode_length_and_check_(p, end, out);
 113 }
 114
 115 void
 116 decode_length_and_check(const char ** p, const char *end, unsigned long & out)
 117 {
 118     decode_length_and_check_(p, end, out);
 119 }
 120
 121 void
 122 decode_length_and_check(const char ** p, const char *end,
 123                         unsigned long long & out)
 124 {
 125     decode_length_and_check_(p, end, out);
 126 }