1 // Methods for Exception Support for -*- C++ -*-
2
3 // Copyright (C) 2014-2019 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 //
26 // ISO C++ 14882: 19.1 Exception classes
27 //
28
29 // Enable hooks for support for the Transactional Memory TS (N4514).
30 #define _GLIBCXX_TM_TS_INTERNAL
31 void
32 _txnal_cow_string_C1_for_exceptions(void* that, const char* s, void* exc);
33 const char*
34 _txnal_cow_string_c_str(const void* that);
35 void
36 _txnal_cow_string_D1(void* that);
37 void
38 _txnal_cow_string_D1_commit(void* that);
39 void*
40 _txnal_logic_error_get_msg(void* e);
41 void*
42 _txnal_runtime_error_get_msg(void* e);
43
44 // All exception classes still use the classic COW std::string.
45 #define _GLIBCXX_USE_CXX11_ABI 0
46 #define _GLIBCXX_DEFINE_STDEXCEPT_COPY_OPS 1
47 #define __cow_string __cow_stringxxx
48 #include <stdexcept>
49 #include <system_error>
50 #undef __cow_string
51
52 namespace std _GLIBCXX_VISIBILITY(default)
53 {
54 _GLIBCXX_BEGIN_NAMESPACE_VERSION
55
56 // Copy/move constructors and assignment operators defined using COW string.
57 // These operations are noexcept even though copying a COW string is not,
58 // but we know that the string member in an exception has not been "leaked"
59 // so copying is a simple reference count increment.
60 // For the fully dynamic string moves are not noexcept (due to needing to
61 // allocate an empty string) so we just define the moves as copies here.
62
logic_error(const logic_error & e)63 logic_error::logic_error(const logic_error& e) noexcept
64 : exception(e), _M_msg(e._M_msg) { }
65
operator =(const logic_error & e)66 logic_error& logic_error::operator=(const logic_error& e) noexcept
67 { _M_msg = e._M_msg; return *this; }
68
69 #if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
70 logic_error::logic_error(logic_error&& e) noexcept = default;
71
72 logic_error&
73 logic_error::operator=(logic_error&& e) noexcept = default;
74 #else
logic_error(logic_error && e)75 logic_error::logic_error(logic_error&& e) noexcept
76 : exception(e), _M_msg(e._M_msg) { }
77
78 logic_error&
operator =(logic_error && e)79 logic_error::operator=(logic_error&& e) noexcept
80 { _M_msg = e._M_msg; return *this; }
81 #endif
82
runtime_error(const runtime_error & e)83 runtime_error::runtime_error(const runtime_error& e) noexcept
84 : exception(e), _M_msg(e._M_msg) { }
85
86 runtime_error&
operator =(const runtime_error & e)87 runtime_error::operator=(const runtime_error& e) noexcept
88 { _M_msg = e._M_msg; return *this; }
89
90 #if _GLIBCXX_FULLY_DYNAMIC_STRING == 0
91 runtime_error::runtime_error(runtime_error&& e) noexcept = default;
92
93 runtime_error&
94 runtime_error::operator=(runtime_error&& e) noexcept = default;
95 #else
runtime_error(runtime_error && e)96 runtime_error::runtime_error(runtime_error&& e) noexcept
97 : exception(e), _M_msg(e._M_msg) { }
98
99 runtime_error&
operator =(runtime_error && e)100 runtime_error::operator=(runtime_error&& e) noexcept
101 { _M_msg = e._M_msg; return *this; }
102 #endif
103
104 // New C++11 constructors:
105
logic_error(const char * __arg)106 logic_error::logic_error(const char* __arg)
107 : exception(), _M_msg(__arg) { }
108
domain_error(const char * __arg)109 domain_error::domain_error(const char* __arg)
110 : logic_error(__arg) { }
111
invalid_argument(const char * __arg)112 invalid_argument::invalid_argument(const char* __arg)
113 : logic_error(__arg) { }
114
length_error(const char * __arg)115 length_error::length_error(const char* __arg)
116 : logic_error(__arg) { }
117
out_of_range(const char * __arg)118 out_of_range::out_of_range(const char* __arg)
119 : logic_error(__arg) { }
120
runtime_error(const char * __arg)121 runtime_error::runtime_error(const char* __arg)
122 : exception(), _M_msg(__arg) { }
123
range_error(const char * __arg)124 range_error::range_error(const char* __arg)
125 : runtime_error(__arg) { }
126
overflow_error(const char * __arg)127 overflow_error::overflow_error(const char* __arg)
128 : runtime_error(__arg) { }
129
underflow_error(const char * __arg)130 underflow_error::underflow_error(const char* __arg)
131 : runtime_error(__arg) { }
132
133 #if _GLIBCXX_USE_DUAL_ABI
134 // Converting constructor from COW std::string to SSO string.
__sso_string(const string & s)135 __sso_string::__sso_string(const string& s)
136 : __sso_string(s.c_str(), s.length()) { }
137
138 // Redefine __cow_string so that we can define and export its members
139 // in terms of the COW std::string.
140 struct __cow_string
141 {
142 union {
143 const char* _M_p;
144 char _M_bytes[sizeof(_M_p)];
145 std::string _M_str;
146 };
147
148 __cow_string();
149 __cow_string(const std::string& s);
150 __cow_string(const char*, size_t n);
151 __cow_string(const __cow_string&) noexcept;
152 __cow_string& operator=(const __cow_string&) noexcept;
153 ~__cow_string();
154 __cow_string(__cow_string&&) noexcept;
155 __cow_string& operator=(__cow_string&&) noexcept;
156 };
157
__cow_string()158 __cow_string::__cow_string() : _M_str() { }
159
__cow_string(const std::string & s)160 __cow_string::__cow_string(const std::string& s) : _M_str(s) { }
161
__cow_string(const char * s,size_t n)162 __cow_string::__cow_string(const char* s, size_t n) : _M_str(s, n) { }
163
__cow_string(const __cow_string & s)164 __cow_string::__cow_string(const __cow_string& s) noexcept
165 : _M_str(s._M_str) { }
166
167 __cow_string&
operator =(const __cow_string & s)168 __cow_string::operator=(const __cow_string& s) noexcept
169 {
170 _M_str = s._M_str;
171 return *this;
172 }
173
~__cow_string()174 __cow_string::~__cow_string() { _M_str.~basic_string(); }
175
__cow_string(__cow_string && s)176 __cow_string::__cow_string(__cow_string&& s) noexcept
177 : _M_str(std::move(s._M_str)) { }
178
179 __cow_string&
operator =(__cow_string && s)180 __cow_string::operator=(__cow_string&& s) noexcept
181 {
182 _M_str = std::move(s._M_str);
183 return *this;
184 }
185
186 static_assert(sizeof(__cow_string) == sizeof(std::string),
187 "sizeof(std::string) has changed");
188 static_assert(alignof(__cow_string) == alignof(std::string),
189 "alignof(std::string) has changed");
190 #endif
191
192 // Return error_category::message() as an SSO string
193 __sso_string
_M_message(int i) const194 error_category::_M_message(int i) const
195 {
196 string msg = this->message(i);
197 return {msg.c_str(), msg.length()};
198 }
199
200 _GLIBCXX_END_NAMESPACE_VERSION
201 } // namespace
202
203 // Support for the Transactional Memory TS (N4514).
204 //
205 // logic_error and runtime_error both carry a message in the form of a COW
206 // string. This COW string is never made visible to users of the exception
207 // because what() returns a C string. The COW string can be constructed as
208 // either a copy of a COW string of another logic_error/runtime_error, or
209 // using a C string or SSO string; thus, the COW string's _Rep is only
210 // accessed by logic_error operations. We control all txnal clones of those
211 // operations and thus can ensure that _Rep is never accessed transactionally.
212 // Furthermore, _Rep will always have been allocated or deallocated via
213 // global new or delete, so nontransactional writes we do to _Rep cannot
214 // interfere with transactional accesses.
215
216 // We depend on having support for referencing functions declared weak that
217 // are not defined by us. Without such support, the exceptions will not be
218 // declared transaction-safe, so we just don't provide transactional clones
219 // in this case.
220 #if _GLIBCXX_USE_WEAK_REF
221 #ifdef _GLIBCXX_USE_C99_STDINT_TR1
222
223 extern "C" {
224
225 #ifndef _GLIBCXX_MANGLE_SIZE_T
226 #error Mangled name of size_t type not defined.
227 #endif
228 #define CONCAT1(x,y) x##y
229 #define CONCAT(x,y) CONCAT1(x,y)
230 #define _ZGTtnaX CONCAT(_ZGTtna,_GLIBCXX_MANGLE_SIZE_T)
231
232 #ifdef __i386__
233 /* Only for 32-bit x86. */
234 # define ITM_REGPARM __attribute__((regparm(2)))
235 #else
236 # define ITM_REGPARM
237 #endif
238
239 // Declare all libitm symbols we rely on, but make them weak so that we do
240 // not depend on libitm.
241 extern void* _ZGTtnaX (size_t sz) __attribute__((weak));
242 extern void _ZGTtdlPv (void* ptr) __attribute__((weak));
243 extern uint8_t _ITM_RU1(const uint8_t *p)
244 ITM_REGPARM __attribute__((weak));
245 extern uint16_t _ITM_RU2(const uint16_t *p)
246 ITM_REGPARM __attribute__((weak));
247 extern uint32_t _ITM_RU4(const uint32_t *p)
248 ITM_REGPARM __attribute__((weak));
249 extern uint64_t _ITM_RU8(const uint64_t *p)
250 ITM_REGPARM __attribute__((weak));
251 extern void _ITM_memcpyRtWn(void *, const void *, size_t)
252 ITM_REGPARM __attribute__((weak));
253 extern void _ITM_memcpyRnWt(void *, const void *, size_t)
254 ITM_REGPARM __attribute__((weak));
255 extern void _ITM_addUserCommitAction(void (*)(void *), uint64_t, void *)
256 ITM_REGPARM __attribute__((weak));
257
258 }
259
260 // A transactional version of basic_string::basic_string(const char *s)
261 // that also notifies the TM runtime about allocations belonging to this
262 // exception.
263 void
_txnal_cow_string_C1_for_exceptions(void * that,const char * s,void * exc)264 _txnal_cow_string_C1_for_exceptions(void* that, const char* s,
265 void *exc __attribute__((unused)))
266 {
267 typedef std::basic_string<char> bs_type;
268 bs_type *bs = (bs_type*) that;
269
270 // First, do a transactional strlen, but including the trailing zero.
271 bs_type::size_type len = 1;
272 for (const char *ss = s; _ITM_RU1((const uint8_t*) ss) != 0; ss++, len++);
273
274
275 // Allocate memory for the string and the refcount. We use the
276 // transactional clone of global new[]; if this throws, it will do so in a
277 // transaction-compatible way.
278 // The allocation belongs to this exception, so tell the runtime about it.
279 // TODO Once this is supported, link the following allocation to this
280 // exception: void *prev = _ITM_setAssociatedException(exc);
281 bs_type::_Rep *rep;
282 __try
283 {
284 rep = (bs_type::_Rep*) _ZGTtnaX (len + sizeof (bs_type::_Rep));
285 }
286 __catch (...)
287 {
288 // Pop the association with this exception.
289 // TODO Once this is supported, link the following allocation to this
290 // exception: _ITM_setAssociatedException(prev);
291 // We do not need to instrument a rethrow.
292 __throw_exception_again;
293 }
294 // Pop the association with this exception.
295 // TODO Once this is supported, link the following allocation to this
296 // exception: _ITM_setAssociatedException(prev);
297
298 // Now initialize the rest of the string and copy the C string. The memory
299 // will be freshly allocated, so nontransactional accesses are sufficient,
300 // including the writes when copying the string (see above).
301 rep->_M_set_sharable();
302 rep->_M_length = rep->_M_capacity = len - 1;
303 _ITM_memcpyRtWn(rep->_M_refdata(), s, len);
304 new (&bs->_M_dataplus) bs_type::_Alloc_hider(rep->_M_refdata(),
305 bs_type::allocator_type());
306 }
307
txnal_read_ptr(void * const * ptr)308 static void* txnal_read_ptr(void* const * ptr)
309 {
310 static_assert(sizeof(uint64_t) == sizeof(void*)
311 || sizeof(uint32_t) == sizeof(void*)
312 || sizeof(uint16_t) == sizeof(void*),
313 "Pointers must be 16 bits, 32 bits or 64 bits wide");
314 #if __UINTPTR_MAX__ == __UINT64_MAX__
315 return (void*)_ITM_RU8((const uint64_t*)ptr);
316 #elif __UINTPTR_MAX__ == __UINT32_MAX__
317 return (void*)_ITM_RU4((const uint32_t*)ptr);
318 #else
319 return (void*)_ITM_RU2((const uint16_t*)ptr);
320 #endif
321 }
322
323 // We must access the data pointer in the COW string transactionally because
324 // another transaction can delete the string and reuse the memory.
325 const char*
_txnal_cow_string_c_str(const void * that)326 _txnal_cow_string_c_str(const void* that)
327 {
328 typedef std::basic_string<char> bs_type;
329 const bs_type *bs = (const bs_type*) that;
330
331 return (const char*) txnal_read_ptr((void**)&bs->_M_dataplus._M_p);
332 }
333
334 #if _GLIBCXX_USE_DUAL_ABI
335 const char*
_txnal_sso_string_c_str(const void * that)336 _txnal_sso_string_c_str(const void* that)
337 {
338 return (const char*) txnal_read_ptr(
339 (void* const*)const_cast<char* const*>(
340 &((const std::__sso_string*) that)->_M_s._M_p));
341 }
342 #endif
343
344 void
_txnal_cow_string_D1_commit(void * data)345 _txnal_cow_string_D1_commit(void* data)
346 {
347 typedef std::basic_string<char> bs_type;
348 bs_type::_Rep *rep = (bs_type::_Rep*) data;
349 rep->_M_dispose(bs_type::allocator_type());
350 }
351
352 void
_txnal_cow_string_D1(void * that)353 _txnal_cow_string_D1(void* that)
354 {
355 typedef std::basic_string<char> bs_type;
356 bs_type::_Rep *rep = reinterpret_cast<bs_type::_Rep*>(
357 const_cast<char*>(_txnal_cow_string_c_str(that))) - 1;
358
359 // The string can be shared, in which case we would need to decrement the
360 // reference count. We cannot undo that because we might lose the string
361 // otherwise. Therefore, we register a commit action that will dispose of
362 // the string's _Rep.
363 enum {_ITM_noTransactionId = 1};
364 _ITM_addUserCommitAction(_txnal_cow_string_D1_commit, _ITM_noTransactionId,
365 rep);
366 }
367
368 void*
_txnal_logic_error_get_msg(void * e)369 _txnal_logic_error_get_msg(void* e)
370 {
371 std::logic_error* le = (std::logic_error*) e;
372 return &le->_M_msg;
373 }
374
375 void*
_txnal_runtime_error_get_msg(void * e)376 _txnal_runtime_error_get_msg(void* e)
377 {
378 std::runtime_error* le = (std::runtime_error*) e;
379 return &le->_M_msg;
380 }
381
382 // The constructors are only declared transaction-safe if the C++11 ABI is
383 // used for std::string and the exception classes use a COW string internally.
384 // A user must not call these constructors otherwise; if they do, it will
385 // result in undefined behavior, which is in this case not initializing this
386 // string.
387 #if _GLIBCXX_USE_DUAL_ABI
388 #define CTORS_FROM_SSOSTRING(NAME, CLASS, BASE) \
389 void \
390 _ZGTtNSt##NAME##C1ERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE( \
391 CLASS* that, const std::__sso_string& s) \
392 { \
393 CLASS e(""); \
394 _ITM_memcpyRnWt(that, &e, sizeof(CLASS)); \
395 /* Get the C string from the SSO string. */ \
396 _txnal_cow_string_C1_for_exceptions(_txnal_##BASE##_get_msg(that), \
397 _txnal_sso_string_c_str(&s), that); \
398 } \
399 void \
400 _ZGTtNSt##NAME##C2ERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE( \
401 CLASS*, const std::__sso_string&) __attribute__((alias \
402 ("_ZGTtNSt" #NAME \
403 "C1ERKNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEEE")));
404 #else
405 #define CTORS_FROM_SSOSTRING(NAME, CLASS, BASE)
406 #endif
407
408 // This macro defines transaction constructors and destructors for a specific
409 // exception class. NAME is the variable part of the mangled name, CLASS is
410 // the class name, and BASE must be logic_error or runtime_error (which is
411 // then used to call the proper friend function that can return a pointer to
412 // the _M_msg member declared by the given (base) class).
413 #define CTORDTOR(NAME, CLASS, BASE) \
414 void \
415 _ZGTtNSt##NAME##C1EPKc (CLASS* that, const char* s) \
416 { \
417 /* This will use the singleton _Rep for an empty string and just \
418 point to it instead of allocating memory. Thus, we can use it as \
419 source, copy it into the object we are constructing, and then \
420 construct the COW string in the latter manually. Note that the \
421 exception classes will not be declared transaction_safe if the \
422 shared empty _Rep is disabled with --enable-fully-dynamic-string \
423 (in which case _GLIBCXX_FULLY_DYNAMIC_STRING is nonzero). */ \
424 CLASS e(""); \
425 _ITM_memcpyRnWt(that, &e, sizeof(CLASS)); \
426 _txnal_cow_string_C1_for_exceptions(_txnal_##BASE##_get_msg(that), \
427 s, that); \
428 } \
429 void \
430 _ZGTtNSt##NAME##C2EPKc (CLASS*, const char*) \
431 __attribute__((alias ("_ZGTtNSt" #NAME "C1EPKc"))); \
432 CTORS_FROM_SSOSTRING(NAME, CLASS, BASE) \
433 void \
434 _ZGTtNSt##NAME##D1Ev(CLASS* that) \
435 { _txnal_cow_string_D1(_txnal_##BASE##_get_msg(that)); } \
436 void \
437 _ZGTtNSt##NAME##D2Ev(CLASS*) \
438 __attribute__((alias ("_ZGTtNSt" #NAME "D1Ev"))); \
439 void \
440 _ZGTtNSt##NAME##D0Ev(CLASS* that) \
441 { \
442 _ZGTtNSt##NAME##D1Ev(that); \
443 _ZGTtdlPv(that); \
444 }
445
446 // Now create all transactional constructors and destructors, as well as the
447 // two virtual what() functions.
448 extern "C" {
449
450 CTORDTOR(11logic_error, std::logic_error, logic_error)
451
452 const char*
_ZGTtNKSt11logic_error4whatEv(const std::logic_error * that)453 _ZGTtNKSt11logic_error4whatEv(const std::logic_error* that)
454 {
455 return _txnal_cow_string_c_str(_txnal_logic_error_get_msg(
456 const_cast<std::logic_error*>(that)));
457 }
458
459 CTORDTOR(12domain_error, std::domain_error, logic_error)
460 CTORDTOR(16invalid_argument, std::invalid_argument, logic_error)
461 CTORDTOR(12length_error, std::length_error, logic_error)
462 CTORDTOR(12out_of_range, std::out_of_range, logic_error)
463
464
465 CTORDTOR(13runtime_error, std::runtime_error, runtime_error)
466
467 const char*
_ZGTtNKSt13runtime_error4whatEv(const std::runtime_error * that)468 _ZGTtNKSt13runtime_error4whatEv(const std::runtime_error* that)
469 {
470 return _txnal_cow_string_c_str(_txnal_runtime_error_get_msg(
471 const_cast<std::runtime_error*>(that)));
472 }
473
474 CTORDTOR(11range_error, std::range_error, runtime_error)
475 CTORDTOR(14overflow_error, std::overflow_error, runtime_error)
476 CTORDTOR(15underflow_error, std::underflow_error, runtime_error)
477
478 }
479
480 #endif // _GLIBCXX_USE_C99_STDINT_TR1
481 #endif // _GLIBCXX_USE_WEAK_REF
482