1// <system_error> -*- C++ -*-
2
3// Copyright (C) 2007-2021 Free Software Foundation, Inc.
4//
5// This file is part of the GNU ISO C++ Library.  This library is free
6// software; you can redistribute it and/or modify it under the
7// terms of the GNU General Public License as published by the
8// Free Software Foundation; either version 3, or (at your option)
9// any later version.
10
11// This library 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// Under Section 7 of GPL version 3, you are granted additional
17// permissions described in the GCC Runtime Library Exception, version
18// 3.1, as published by the Free Software Foundation.
19
20// You should have received a copy of the GNU General Public License and
21// a copy of the GCC Runtime Library Exception along with this program;
22// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
23// <http://www.gnu.org/licenses/>.
24
25/** @file include/system_error
26 *  This is a Standard C++ Library header.
27 */
28
29#ifndef _GLIBCXX_SYSTEM_ERROR
30#define _GLIBCXX_SYSTEM_ERROR 1
31
32#pragma GCC system_header
33
34#if __cplusplus < 201103L
35# include <bits/c++0x_warning.h>
36#else
37
38#include <bits/c++config.h>
39#include <bits/error_constants.h>
40#include <iosfwd>
41#include <stdexcept>
42#if __cplusplus > 201703L
43# include <compare>
44#endif
45
46namespace std _GLIBCXX_VISIBILITY(default)
47{
48_GLIBCXX_BEGIN_NAMESPACE_VERSION
49
50  /** @addtogroup diagnostics
51   * @{
52   */
53
54  class error_code;
55  class error_condition;
56  class system_error;
57
58  /// is_error_code_enum
59  template<typename _Tp>
60    struct is_error_code_enum : public false_type { };
61
62  /// is_error_condition_enum
63  template<typename _Tp>
64    struct is_error_condition_enum : public false_type { };
65
66  template<>
67    struct is_error_condition_enum<errc>
68    : public true_type { };
69
70#if __cplusplus > 201402L
71  template <typename _Tp>
72    inline constexpr bool is_error_code_enum_v =
73      is_error_code_enum<_Tp>::value;
74  template <typename _Tp>
75    inline constexpr bool is_error_condition_enum_v =
76      is_error_condition_enum<_Tp>::value;
77#endif // C++17
78  /// @}
79
80  inline namespace _V2 {
81
82  /** @addtogroup diagnostics
83   * @{
84   */
85
86  /** Abstract base class for types defining a category of error codes.
87   *
88   * An error category defines a context that give meaning to the integer
89   * stored in an `error_code` or `error_condition` object. For example,
90   * the standard `errno` constants such a `EINVAL` and `ENOMEM` are
91   * associated with the "generic" category and other OS-specific error
92   * numbers are associated with the "system" category, but a user-defined
93   * category might give different meanings to the same numerical values.
94   *
95   * @since C++11
96   */
97  class error_category
98  {
99  public:
100    constexpr error_category() noexcept = default;
101
102    virtual ~error_category();
103
104    error_category(const error_category&) = delete;
105    error_category& operator=(const error_category&) = delete;
106
107    virtual const char*
108    name() const noexcept = 0;
109
110    // We need two different virtual functions here, one returning a
111    // COW string and one returning an SSO string. Their positions in the
112    // vtable must be consistent for dynamic dispatch to work, but which one
113    // the name "message()" finds depends on which ABI the caller is using.
114#if _GLIBCXX_USE_CXX11_ABI
115  private:
116    _GLIBCXX_DEFAULT_ABI_TAG
117    virtual __cow_string
118    _M_message(int) const;
119
120  public:
121    _GLIBCXX_DEFAULT_ABI_TAG
122    virtual string
123    message(int) const = 0;
124#else
125    virtual string
126    message(int) const = 0;
127
128  private:
129    virtual __sso_string
130    _M_message(int) const;
131#endif
132
133  public:
134    virtual error_condition
135    default_error_condition(int __i) const noexcept;
136
137    virtual bool
138    equivalent(int __i, const error_condition& __cond) const noexcept;
139
140    virtual bool
141    equivalent(const error_code& __code, int __i) const noexcept;
142
143    bool
144    operator==(const error_category& __other) const noexcept
145    { return this == &__other; }
146
147#if __cpp_lib_three_way_comparison
148    strong_ordering
149    operator<=>(const error_category& __rhs) const noexcept
150    { return std::compare_three_way()(this, &__rhs); }
151#else
152    bool
153    operator!=(const error_category& __other) const noexcept
154    { return this != &__other; }
155
156    bool
157    operator<(const error_category& __other) const noexcept
158    { return less<const error_category*>()(this, &__other); }
159#endif
160  };
161
162  // DR 890.
163
164  /// Error category for `errno` error codes.
165  _GLIBCXX_CONST const error_category& generic_category() noexcept;
166
167  /// Error category for other error codes defined by the OS.
168  _GLIBCXX_CONST const error_category& system_category() noexcept;
169
170  /// @}
171  } // end inline namespace
172
173  /** @addtogroup diagnostics
174   * @{
175   */
176
177  error_code make_error_code(errc) noexcept;
178
179  /** Class error_code
180   *
181   * This class is a value type storing an integer error number and a
182   * category that gives meaning to the error number. Typically this is done
183   * close the the point where the error happens, to capture the original
184   * error value.
185   *
186   * An `error_code` object can be used to store the original error value
187   * emitted by some subsystem, with a category relevant to the subsystem.
188   * For example, errors from POSIX library functions can be represented by
189   * an `errno` value and the "generic" category, but errors from an HTTP
190   * library might be represented by an HTTP response status code (e.g. 404)
191   * and a custom category defined by the library.
192   *
193   * @since C++11
194   * @ingroup diagnostics
195   */
196  class error_code
197  {
198  public:
199    error_code() noexcept
200    : _M_value(0), _M_cat(&system_category()) { }
201
202    error_code(int __v, const error_category& __cat) noexcept
203    : _M_value(__v), _M_cat(&__cat) { }
204
205    template<typename _ErrorCodeEnum, typename = typename
206	     enable_if<is_error_code_enum<_ErrorCodeEnum>::value>::type>
207      error_code(_ErrorCodeEnum __e) noexcept
208      { *this = make_error_code(__e); }
209
210    void
211    assign(int __v, const error_category& __cat) noexcept
212    {
213      _M_value = __v;
214      _M_cat = &__cat;
215    }
216
217    void
218    clear() noexcept
219    { assign(0, system_category()); }
220
221    // DR 804.
222    template<typename _ErrorCodeEnum>
223      typename enable_if<is_error_code_enum<_ErrorCodeEnum>::value,
224			 error_code&>::type
225      operator=(_ErrorCodeEnum __e) noexcept
226      { return *this = make_error_code(__e); }
227
228    int
229    value() const noexcept { return _M_value; }
230
231    const error_category&
232    category() const noexcept { return *_M_cat; }
233
234    error_condition
235    default_error_condition() const noexcept;
236
237    _GLIBCXX_DEFAULT_ABI_TAG
238    string
239    message() const
240    { return category().message(value()); }
241
242    explicit operator bool() const noexcept
243    { return _M_value != 0; }
244
245    // DR 804.
246  private:
247    int            		_M_value;
248    const error_category* 	_M_cat;
249  };
250
251  // 19.4.2.6 non-member functions
252
253  /// @relates error_code @{
254
255  inline error_code
256  make_error_code(errc __e) noexcept
257  { return error_code(static_cast<int>(__e), generic_category()); }
258
259#if __cpp_lib_three_way_comparison
260  inline strong_ordering
261  operator<=>(const error_code& __lhs, const error_code& __rhs) noexcept
262  {
263    if (auto __c = __lhs.category() <=> __rhs.category(); __c != 0)
264      return __c;
265    return __lhs.value() <=> __rhs.value();
266  }
267#else
268  inline bool
269  operator<(const error_code& __lhs, const error_code& __rhs) noexcept
270  {
271    return (__lhs.category() < __rhs.category()
272	    || (__lhs.category() == __rhs.category()
273		&& __lhs.value() < __rhs.value()));
274  }
275#endif
276
277  template<typename _CharT, typename _Traits>
278    basic_ostream<_CharT, _Traits>&
279    operator<<(basic_ostream<_CharT, _Traits>& __os, const error_code& __e)
280    { return (__os << __e.category().name() << ':' << __e.value()); }
281
282  /// @}
283
284  error_condition make_error_condition(errc) noexcept;
285
286  /** Class error_condition
287   *
288   * This class represents error conditions that may be visible at an API
289   * boundary. Different `error_code` values that can occur within a library
290   * or module might map to the same `error_condition`.
291   *
292   * An `error_condition` represents something that the program can test for,
293   * and subsequently take appropriate action.
294   *
295   * @since C++11
296   */
297  class error_condition
298  {
299  public:
300    error_condition() noexcept
301    : _M_value(0), _M_cat(&generic_category()) { }
302
303    error_condition(int __v, const error_category& __cat) noexcept
304    : _M_value(__v), _M_cat(&__cat) { }
305
306    template<typename _ErrorConditionEnum, typename = typename
307	 enable_if<is_error_condition_enum<_ErrorConditionEnum>::value>::type>
308      error_condition(_ErrorConditionEnum __e) noexcept
309      { *this = make_error_condition(__e); }
310
311    void
312    assign(int __v, const error_category& __cat) noexcept
313    {
314      _M_value = __v;
315      _M_cat = &__cat;
316    }
317
318    // DR 804.
319    template<typename _ErrorConditionEnum>
320      typename enable_if<is_error_condition_enum
321			 <_ErrorConditionEnum>::value, error_condition&>::type
322      operator=(_ErrorConditionEnum __e) noexcept
323      { return *this = make_error_condition(__e); }
324
325    void
326    clear() noexcept
327    { assign(0, generic_category()); }
328
329    // 19.4.3.4 observers
330    int
331    value() const noexcept { return _M_value; }
332
333    const error_category&
334    category() const noexcept { return *_M_cat; }
335
336    _GLIBCXX_DEFAULT_ABI_TAG
337    string
338    message() const
339    { return category().message(value()); }
340
341    explicit operator bool() const noexcept
342    { return _M_value != 0; }
343
344    // DR 804.
345  private:
346    int 			_M_value;
347    const error_category* 	_M_cat;
348  };
349
350  // 19.4.3.6 non-member functions
351
352  /// Create an `error_condition` representing a standard `errc` condition.
353  /// @relates error_condition
354  inline error_condition
355  make_error_condition(errc __e) noexcept
356  { return error_condition(static_cast<int>(__e), generic_category()); }
357
358  // 19.4.4 Comparison operators
359
360  /// @relates error_code
361  inline bool
362  operator==(const error_code& __lhs, const error_code& __rhs) noexcept
363  { return (__lhs.category() == __rhs.category()
364	    && __lhs.value() == __rhs.value()); }
365
366  /// @relates error_code
367  inline bool
368  operator==(const error_code& __lhs, const error_condition& __rhs) noexcept
369  {
370    return (__lhs.category().equivalent(__lhs.value(), __rhs)
371	    || __rhs.category().equivalent(__lhs, __rhs.value()));
372  }
373
374  /// @relates error_condition
375  inline bool
376  operator==(const error_condition& __lhs,
377	     const error_condition& __rhs) noexcept
378  {
379    return (__lhs.category() == __rhs.category()
380	    && __lhs.value() == __rhs.value());
381  }
382
383#if __cpp_lib_three_way_comparison
384  /// Define an ordering for error_condition objects.
385  /// @relates error_condition
386  inline strong_ordering
387  operator<=>(const error_condition& __lhs,
388	      const error_condition& __rhs) noexcept
389  {
390    if (auto __c = __lhs.category() <=> __rhs.category(); __c != 0)
391      return __c;
392    return __lhs.value() <=> __rhs.value();
393  }
394#else
395  /// Define an ordering for error_condition objects.
396  /// @relates error_condition
397  inline bool
398  operator<(const error_condition& __lhs,
399	    const error_condition& __rhs) noexcept
400  {
401    return (__lhs.category() < __rhs.category()
402	    || (__lhs.category() == __rhs.category()
403		&& __lhs.value() < __rhs.value()));
404  }
405
406  /// @relates error_condition
407  inline bool
408  operator==(const error_condition& __lhs, const error_code& __rhs) noexcept
409  {
410    return (__rhs.category().equivalent(__rhs.value(), __lhs)
411	    || __lhs.category().equivalent(__rhs, __lhs.value()));
412  }
413
414  /// @relates error_code
415  inline bool
416  operator!=(const error_code& __lhs, const error_code& __rhs) noexcept
417  { return !(__lhs == __rhs); }
418
419  /// @relates error_code
420  inline bool
421  operator!=(const error_code& __lhs, const error_condition& __rhs) noexcept
422  { return !(__lhs == __rhs); }
423
424  /// @relates error_condition
425  inline bool
426  operator!=(const error_condition& __lhs, const error_code& __rhs) noexcept
427  { return !(__lhs == __rhs); }
428
429  /// @relates error_condition
430  inline bool
431  operator!=(const error_condition& __lhs,
432	     const error_condition& __rhs) noexcept
433  { return !(__lhs == __rhs); }
434#endif // three_way_comparison
435  /// @}
436
437  /**
438   * @brief An exception type that includes an `error_code` value.
439   *
440   * Typically used to report errors from the operating system and other
441   * low-level APIs.
442   *
443   * @since C++11
444   * @ingroup exceptions
445   */
446  class system_error : public std::runtime_error
447  {
448  private:
449    error_code 	_M_code;
450
451  public:
452    system_error(error_code __ec = error_code())
453    : runtime_error(__ec.message()), _M_code(__ec) { }
454
455    system_error(error_code __ec, const string& __what)
456    : runtime_error(__what + ": " + __ec.message()), _M_code(__ec) { }
457
458    system_error(error_code __ec, const char* __what)
459    : runtime_error(__what + (": " + __ec.message())), _M_code(__ec) { }
460
461    system_error(int __v, const error_category& __ecat, const char* __what)
462    : system_error(error_code(__v, __ecat), __what) { }
463
464    system_error(int __v, const error_category& __ecat)
465    : runtime_error(error_code(__v, __ecat).message()),
466      _M_code(__v, __ecat) { }
467
468    system_error(int __v, const error_category& __ecat, const string& __what)
469    : runtime_error(__what + ": " + error_code(__v, __ecat).message()),
470      _M_code(__v, __ecat) { }
471
472#if __cplusplus >= 201103L
473    system_error (const system_error &) = default;
474    system_error &operator= (const system_error &) = default;
475#endif
476
477    virtual ~system_error() noexcept;
478
479    const error_code&
480    code() const noexcept { return _M_code; }
481  };
482
483_GLIBCXX_END_NAMESPACE_VERSION
484} // namespace
485
486#include <bits/functional_hash.h>
487
488namespace std _GLIBCXX_VISIBILITY(default)
489{
490_GLIBCXX_BEGIN_NAMESPACE_VERSION
491
492#ifndef _GLIBCXX_COMPATIBILITY_CXX0X
493  // DR 1182.
494  /// std::hash specialization for error_code.
495  /// @relates error_code
496  template<>
497    struct hash<error_code>
498    : public __hash_base<size_t, error_code>
499    {
500      size_t
501      operator()(const error_code& __e) const noexcept
502      {
503	const size_t __tmp = std::_Hash_impl::hash(__e.value());
504	return std::_Hash_impl::__hash_combine(&__e.category(), __tmp);
505      }
506    };
507#endif // _GLIBCXX_COMPATIBILITY_CXX0X
508
509#if __cplusplus >= 201703L
510  // DR 2686.
511  /// std::hash specialization for error_condition.
512  /// @relates error_condition
513  template<>
514    struct hash<error_condition>
515    : public __hash_base<size_t, error_condition>
516    {
517      size_t
518      operator()(const error_condition& __e) const noexcept
519      {
520	const size_t __tmp = std::_Hash_impl::hash(__e.value());
521	return std::_Hash_impl::__hash_combine(&__e.category(), __tmp);
522      }
523    };
524#endif
525
526_GLIBCXX_END_NAMESPACE_VERSION
527} // namespace
528
529#endif // C++11
530
531#endif // _GLIBCXX_SYSTEM_ERROR
532