xapian-applications/omega/jsonescape.cc

   1 /** @file
   2  * @brief JSON escape a string
   3  */
   4 /* Copyright (C) 2013,2023 Olly Betts
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to
   8  * deal in the Software without restriction, including without limitation the
   9  * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
  10  * sell copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  22  * IN THE SOFTWARE.
  23  */
  24
  25 #include <config.h>
  26
  27 #include "jsonescape.h"
  28
  29 #include <string>
  30
  31 #include <xapian.h>
  32
  33 using namespace std;
  34
  35 enum { UNI = 0, CLR = 1 };
  36
  37 static const char json_tab['"' + 1] = {
  38     UNI, UNI, UNI, UNI, UNI, UNI, UNI, UNI, // 0-7
  39     'b', 't', 'n', UNI, 'f', 'r', UNI, UNI, // 8-15
  40     UNI, UNI, UNI, UNI, UNI, UNI, UNI, UNI, // 16-23
  41     UNI, UNI, UNI, UNI, UNI, UNI, UNI, UNI, // 24-31
  42     CLR, CLR, '"'
  43 };
  44
  45 void
  46 json_escape(string &s)
  47 {
  48     string r;
  49     for (Xapian::Utf8Iterator i(s); i != Xapian::Utf8Iterator(); ++i) {
  50         unsigned int ch = *i;
  51         if (ch >= 128) {
  52             Xapian::Unicode::append_utf8(r, ch);
  53             continue;
  54         }
  55         if (ch > '"') {
  56             if (ch != '\\') {
  57                 r += ch;
  58                 continue;
  59             }
  60         } else {
  61             unsigned char t = json_tab[ch];
  62             if (t == CLR) {
  63                 // Can be sent "in the clear".
  64                 r += ch;
  65                 continue;
  66             }
  67             if (t == UNI) {
  68                 // Encode as Unicode escape sequence.  We know ch <= 0x1f.
  69                 r.append("\\u0000", 6);
  70                 if (ch >= 16) r[r.size() - 2] = '1';
  71                 r.back() = "0123456789abcdef"[ch & 0x0f];
  72                 continue;
  73             }
  74             ch = t;
  75         }
  76         char buf[2] = {'\\', char(ch)};
  77         r.append(buf, 2);
  78     }
  79     swap(s, r);
  80 }