src/base/TextException.cc

   1 /*
   2  * Copyright (C) 1996-2020 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 #include "squid.h"
  10 #include "base/TextException.h"
  11 #include "sbuf/SBuf.h"
  12
  13 #include <iostream>
  14 #include <sstream>
  15 #include <unordered_map>
  16
  17 /// a standard CoW string; avoids noise and circular dependencies of SBuf
  18 typedef std::runtime_error WhatString;
  19
  20 /// a collection of strings indexed by pointers to their creator objects
  21 typedef std::unordered_multimap<const void*, WhatString> WhatStrings;
  22
  23 /// requested what() strings of alive TextException objects
  24 static WhatStrings *WhatStrings_ = nullptr;
  25
  26 TextException::TextException(SBuf message, const SourceLocation &location):
  27     TextException(message.c_str(), location)
  28 {}
  29
  30 TextException::~TextException() throw()
  31 {
  32     if (WhatStrings_)
  33         WhatStrings_->erase(this); // there only if what() has been called
  34 }
  35
  36 std::ostream &
  37 TextException::print(std::ostream &os) const
  38 {
  39     os << std::runtime_error::what() <<
  40        Debug::Extra << "exception location: " << where;
  41     // TODO: ...error_detail: " << (ERR_DETAIL_EXCEPTION_START+id());
  42     return os;
  43 }
  44
  45 const char *
  46 TextException::what() const throw()
  47 {
  48     std::ostringstream os;
  49     print(os);
  50     const WhatString result(os.str());
  51
  52     // extend result.c_str() lifetime to this object lifetime
  53     if (!WhatStrings_)
  54         WhatStrings_ = new WhatStrings;
  55     // *this could change, but we must preserve old results for they may be used
  56     WhatStrings_->emplace(std::make_pair(this, result));
  57
  58     return result.what();
  59 }
  60
  61 std::ostream &
  62 operator <<(std::ostream &os, const TextException &ex)
  63 {
  64     ex.print(os);
  65     return os;
  66 }
  67
  68 std::ostream &
  69 CurrentException(std::ostream &os)
  70 {
  71     if (std::current_exception()) {
  72         try {
  73             throw; // re-throw to recognize the exception type
  74         }
  75         catch (const TextException &ex) {
  76             os << ex; // optimization: this is a lot cheaper than what() below
  77         }
  78         catch (const std::exception &ex) {
  79             os << ex.what();
  80         }
  81         catch (...) {
  82             os << "[unknown exception type]";
  83         }
  84     } else {
  85         os << "[no active exception]";
  86     }
  87     return os;
  88 }
  89