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1 //===----------------------- private_typeinfo.cpp -------------------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 
10 #include "private_typeinfo.h"
11 
12 // The flag _LIBCXX_DYNAMIC_FALLBACK is used to make dynamic_cast more
13 // forgiving when type_info's mistakenly have hidden visibility and thus
14 // multiple type_infos can exist for a single type.
15 //
16 // When _LIBCXX_DYNAMIC_FALLBACK is defined, and only in the case where
17 // there is a detected inconsistency in the type_info hierarchy during a
18 // dynamic_cast, then the equality operation will fall back to using strcmp
19 // on type_info names to determine type_info equality.
20 //
21 // This change happens *only* under dynamic_cast, and only when
22 // dynamic_cast is faced with the choice:  abort, or possibly give back the
23 // wrong answer.  If when the dynamic_cast is done with this fallback
24 // algorithm and an inconsistency is still detected, dynamic_cast will call
25 // abort with an appropriate message.
26 //
27 // The current implementation of _LIBCXX_DYNAMIC_FALLBACK requires a
28 // printf-like function called syslog:
29 //
30 //     void syslog(int facility_priority, const char* format, ...);
31 //
32 // If you want this functionality but your platform doesn't have syslog,
33 // just implement it in terms of fprintf(stderr, ...).
34 //
35 // _LIBCXX_DYNAMIC_FALLBACK is currently off by default.
36 
37 
38 #include <string.h>
39 
40 
41 #ifdef _LIBCXX_DYNAMIC_FALLBACK
42 #include "abort_message.h"
43 #include <sys/syslog.h>
44 #endif
45 
46 // On Windows, typeids are different between DLLs and EXEs, so comparing
47 // type_info* will work for typeids from the same compiled file but fail
48 // for typeids from a DLL and an executable. Among other things, exceptions
49 // are not caught by handlers since can_catch() returns false.
50 //
51 // Defining _LIBCXX_DYNAMIC_FALLBACK does not help since can_catch() calls
52 // is_equal() with use_strcmp=false so the string names are not compared.
53 
54 #ifdef _WIN32
55 #include <string.h>
56 #endif
57 
58 namespace __cxxabiv1
59 {
60 
61 #pragma GCC visibility push(hidden)
62 
63 inline
64 bool
is_equal(const std::type_info * x,const std::type_info * y,bool use_strcmp)65 is_equal(const std::type_info* x, const std::type_info* y, bool use_strcmp)
66 {
67 #ifndef _WIN32
68     if (!use_strcmp)
69         return x == y;
70     return strcmp(x->name(), y->name()) == 0;
71 #else
72     return (x == y) || (strcmp(x->name(), y->name()) == 0);
73 #endif
74 }
75 
76 
77 // __shim_type_info
78 
~__shim_type_info()79 __shim_type_info::~__shim_type_info()
80 {
81 }
82 
noop1() const83 void __shim_type_info::noop1() const {}
noop2() const84 void __shim_type_info::noop2() const {}
85 
86 // __fundamental_type_info
87 
88 // This miraculously (compiler magic) emits the type_info's for:
89 //   1. all of the fundamental types
90 //   2. pointers to all of the fundamental types
91 //   3. pointers to all of the const fundamental types
~__fundamental_type_info()92 __fundamental_type_info::~__fundamental_type_info()
93 {
94 }
95 
96 // __array_type_info
97 
~__array_type_info()98 __array_type_info::~__array_type_info()
99 {
100 }
101 
102 // __function_type_info
103 
~__function_type_info()104 __function_type_info::~__function_type_info()
105 {
106 }
107 
108 // __enum_type_info
109 
~__enum_type_info()110 __enum_type_info::~__enum_type_info()
111 {
112 }
113 
114 // __class_type_info
115 
~__class_type_info()116 __class_type_info::~__class_type_info()
117 {
118 }
119 
120 // __si_class_type_info
121 
~__si_class_type_info()122 __si_class_type_info::~__si_class_type_info()
123 {
124 }
125 
126 // __vmi_class_type_info
127 
~__vmi_class_type_info()128 __vmi_class_type_info::~__vmi_class_type_info()
129 {
130 }
131 
132 // __pbase_type_info
133 
~__pbase_type_info()134 __pbase_type_info::~__pbase_type_info()
135 {
136 }
137 
138 // __pointer_type_info
139 
~__pointer_type_info()140 __pointer_type_info::~__pointer_type_info()
141 {
142 }
143 
144 // __pointer_to_member_type_info
145 
~__pointer_to_member_type_info()146 __pointer_to_member_type_info::~__pointer_to_member_type_info()
147 {
148 }
149 
150 // can_catch
151 
152 // A handler is a match for an exception object of type E if
153 //   1. The handler is of type cv T or cv T& and E and T are the same type
154 //      (ignoring the top-level cv-qualifiers), or
155 //   2. the handler is of type cv T or cv T& and T is an unambiguous public
156 //       base class of E, or
157 //   3. the handler is of type cv1 T* cv2 and E is a pointer type that can be
158 //      converted to the type of the handler by either or both of
159 //      A. a standard pointer conversion (4.10) not involving conversions to
160 //         pointers to private or protected or ambiguous classes
161 //      B. a qualification conversion
162 //   4. the handler is a pointer or pointer to member type and E is
163 //      std::nullptr_t.
164 
165 // adjustedPtr:
166 //
167 // catch (A& a) : adjustedPtr == &a
168 // catch (A* a) : adjustedPtr == a
169 // catch (A** a) : adjustedPtr == a
170 //
171 // catch (D2& d2) : adjustedPtr == &d2  (d2 is base class of thrown object)
172 // catch (D2* d2) : adjustedPtr == d2
173 // catch (D2*& d2) : adjustedPtr == d2
174 //
175 // catch (...) : adjustedPtr == & of the exception
176 //
177 // If the thrown type is nullptr_t and the caught type is a pointer to
178 // member type, adjustedPtr points to a statically-allocated null pointer
179 // representation of that type.
180 
181 // Handles bullet 1
182 bool
can_catch(const __shim_type_info * thrown_type,void * &) const183 __fundamental_type_info::can_catch(const __shim_type_info* thrown_type,
184                                    void*&) const
185 {
186     return is_equal(this, thrown_type, false);
187 }
188 
189 bool
can_catch(const __shim_type_info *,void * &) const190 __array_type_info::can_catch(const __shim_type_info*, void*&) const
191 {
192     // We can get here if someone tries to catch an array by reference.
193     //   However if someone tries to throw an array, it immediately gets
194     //   converted to a pointer, which will not convert back to an array
195     //   at the catch clause.  So this can never catch anything.
196     return false;
197 }
198 
199 bool
can_catch(const __shim_type_info *,void * &) const200 __function_type_info::can_catch(const __shim_type_info*, void*&) const
201 {
202     // We can get here if someone tries to catch a function by reference.
203     //   However if someone tries to throw a function, it immediately gets
204     //   converted to a pointer, which will not convert back to a function
205     //   at the catch clause.  So this can never catch anything.
206     return false;
207 }
208 
209 // Handles bullet 1
210 bool
can_catch(const __shim_type_info * thrown_type,void * &) const211 __enum_type_info::can_catch(const __shim_type_info* thrown_type,
212                             void*&) const
213 {
214     return is_equal(this, thrown_type, false);
215 }
216 
217 #ifdef __clang__
218 #pragma clang diagnostic push
219 #pragma clang diagnostic ignored "-Wmissing-field-initializers"
220 #endif
221 
222 // Handles bullets 1 and 2
223 bool
can_catch(const __shim_type_info * thrown_type,void * & adjustedPtr) const224 __class_type_info::can_catch(const __shim_type_info* thrown_type,
225                              void*& adjustedPtr) const
226 {
227     // bullet 1
228     if (is_equal(this, thrown_type, false))
229         return true;
230     const __class_type_info* thrown_class_type =
231         dynamic_cast<const __class_type_info*>(thrown_type);
232     if (thrown_class_type == 0)
233         return false;
234     // bullet 2
235     __dynamic_cast_info info = {thrown_class_type, 0, this, -1, 0};
236     info.number_of_dst_type = 1;
237     thrown_class_type->has_unambiguous_public_base(&info, adjustedPtr, public_path);
238     if (info.path_dst_ptr_to_static_ptr == public_path)
239     {
240         adjustedPtr = const_cast<void*>(info.dst_ptr_leading_to_static_ptr);
241         return true;
242     }
243     return false;
244 }
245 
246 #ifdef __clang__
247 #pragma clang diagnostic pop
248 #endif
249 
250 void
process_found_base_class(__dynamic_cast_info * info,void * adjustedPtr,int path_below) const251 __class_type_info::process_found_base_class(__dynamic_cast_info* info,
252                                                void* adjustedPtr,
253                                                int path_below) const
254 {
255     if (info->dst_ptr_leading_to_static_ptr == 0)
256     {
257         // First time here
258         info->dst_ptr_leading_to_static_ptr = adjustedPtr;
259         info->path_dst_ptr_to_static_ptr = path_below;
260         info->number_to_static_ptr = 1;
261     }
262     else if (info->dst_ptr_leading_to_static_ptr == adjustedPtr)
263     {
264         // We've been here before.  Update path to "most public"
265         if (info->path_dst_ptr_to_static_ptr == not_public_path)
266             info->path_dst_ptr_to_static_ptr = path_below;
267     }
268     else
269     {
270         // We've detected an ambiguous cast from (thrown_class_type, adjustedPtr)
271         //   to a static_type
272         info->number_to_static_ptr += 1;
273         info->path_dst_ptr_to_static_ptr = not_public_path;
274         info->search_done = true;
275     }
276 }
277 
278 void
has_unambiguous_public_base(__dynamic_cast_info * info,void * adjustedPtr,int path_below) const279 __class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
280                                                void* adjustedPtr,
281                                                int path_below) const
282 {
283     if (is_equal(this, info->static_type, false))
284         process_found_base_class(info, adjustedPtr, path_below);
285 }
286 
287 void
has_unambiguous_public_base(__dynamic_cast_info * info,void * adjustedPtr,int path_below) const288 __si_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
289                                                   void* adjustedPtr,
290                                                   int path_below) const
291 {
292     if (is_equal(this, info->static_type, false))
293         process_found_base_class(info, adjustedPtr, path_below);
294     else
295         __base_type->has_unambiguous_public_base(info, adjustedPtr, path_below);
296 }
297 
298 void
has_unambiguous_public_base(__dynamic_cast_info * info,void * adjustedPtr,int path_below) const299 __base_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
300                                                     void* adjustedPtr,
301                                                     int path_below) const
302 {
303     ptrdiff_t offset_to_base = 0;
304     if (adjustedPtr != nullptr)
305     {
306         offset_to_base = __offset_flags >> __offset_shift;
307         if (__offset_flags & __virtual_mask)
308         {
309             const char* vtable = *static_cast<const char*const*>(adjustedPtr);
310             offset_to_base = *reinterpret_cast<const ptrdiff_t*>(vtable + offset_to_base);
311         }
312     }
313     __base_type->has_unambiguous_public_base(
314             info,
315             static_cast<char*>(adjustedPtr) + offset_to_base,
316             (__offset_flags & __public_mask) ? path_below : not_public_path);
317 }
318 
319 void
has_unambiguous_public_base(__dynamic_cast_info * info,void * adjustedPtr,int path_below) const320 __vmi_class_type_info::has_unambiguous_public_base(__dynamic_cast_info* info,
321                                                    void* adjustedPtr,
322                                                    int path_below) const
323 {
324     if (is_equal(this, info->static_type, false))
325         process_found_base_class(info, adjustedPtr, path_below);
326     else
327     {
328         typedef const __base_class_type_info* Iter;
329         const Iter e = __base_info + __base_count;
330         Iter p = __base_info;
331         p->has_unambiguous_public_base(info, adjustedPtr, path_below);
332         if (++p < e)
333         {
334             do
335             {
336                 p->has_unambiguous_public_base(info, adjustedPtr, path_below);
337                 if (info->search_done)
338                     break;
339             } while (++p < e);
340         }
341     }
342 }
343 
344 // Handles bullet 1 for both pointers and member pointers
345 bool
can_catch(const __shim_type_info * thrown_type,void * &) const346 __pbase_type_info::can_catch(const __shim_type_info* thrown_type,
347                              void*&) const
348 {
349     bool use_strcmp = this->__flags & (__incomplete_class_mask |
350                                        __incomplete_mask);
351     if (!use_strcmp) {
352         const __pbase_type_info* thrown_pbase = dynamic_cast<const __pbase_type_info*>(
353                 thrown_type);
354         if (!thrown_pbase) return false;
355         use_strcmp = thrown_pbase->__flags & (__incomplete_class_mask |
356                                               __incomplete_mask);
357     }
358     return is_equal(this, thrown_type, use_strcmp);
359 }
360 
361 #ifdef __clang__
362 #pragma clang diagnostic push
363 #pragma clang diagnostic ignored "-Wmissing-field-initializers"
364 #endif
365 
366 // Handles bullets 1, 3 and 4
367 // NOTE: It might not be safe to adjust the pointer if it is not not a pointer
368 // type. Only adjust the pointer after we know it is safe to do so.
369 bool
can_catch(const __shim_type_info * thrown_type,void * & adjustedPtr) const370 __pointer_type_info::can_catch(const __shim_type_info* thrown_type,
371                                void*& adjustedPtr) const
372 {
373     // bullet 4
374     if (is_equal(thrown_type, &typeid(std::nullptr_t), false)) {
375       adjustedPtr = nullptr;
376       return true;
377     }
378 
379     // bullet 1
380     if (__pbase_type_info::can_catch(thrown_type, adjustedPtr)) {
381         if (adjustedPtr != NULL)
382             adjustedPtr = *static_cast<void**>(adjustedPtr);
383         return true;
384     }
385     // bullet 3
386     const __pointer_type_info* thrown_pointer_type =
387         dynamic_cast<const __pointer_type_info*>(thrown_type);
388     if (thrown_pointer_type == 0)
389         return false;
390     // Do the dereference adjustment
391     if (adjustedPtr != NULL)
392         adjustedPtr = *static_cast<void**>(adjustedPtr);
393     // bullet 3B and 3C
394     if (thrown_pointer_type->__flags & ~__flags & __no_remove_flags_mask)
395         return false;
396     if (__flags & ~thrown_pointer_type->__flags & __no_add_flags_mask)
397         return false;
398     if (is_equal(__pointee, thrown_pointer_type->__pointee, false))
399         return true;
400     // bullet 3A
401     if (is_equal(__pointee, &typeid(void), false)) {
402         // pointers to functions cannot be converted to void*.
403         // pointers to member functions are not handled here.
404         const __function_type_info* thrown_function =
405             dynamic_cast<const __function_type_info*>(thrown_pointer_type->__pointee);
406         return (thrown_function == nullptr);
407     }
408     // Handle pointer to pointer
409     const __pointer_type_info* nested_pointer_type =
410         dynamic_cast<const __pointer_type_info*>(__pointee);
411     if (nested_pointer_type) {
412         if (~__flags & __const_mask) return false;
413         return nested_pointer_type->can_catch_nested(thrown_pointer_type->__pointee);
414     }
415 
416     // Handle pointer to pointer to member
417     const __pointer_to_member_type_info* member_ptr_type =
418         dynamic_cast<const __pointer_to_member_type_info*>(__pointee);
419     if (member_ptr_type) {
420         if (~__flags & __const_mask) return false;
421         return member_ptr_type->can_catch_nested(thrown_pointer_type->__pointee);
422     }
423 
424     // Handle pointer to class type
425     const __class_type_info* catch_class_type =
426         dynamic_cast<const __class_type_info*>(__pointee);
427     if (catch_class_type == 0)
428         return false;
429     const __class_type_info* thrown_class_type =
430         dynamic_cast<const __class_type_info*>(thrown_pointer_type->__pointee);
431     if (thrown_class_type == 0)
432         return false;
433     __dynamic_cast_info info = {thrown_class_type, 0, catch_class_type, -1, 0};
434     info.number_of_dst_type = 1;
435     thrown_class_type->has_unambiguous_public_base(&info, adjustedPtr, public_path);
436     if (info.path_dst_ptr_to_static_ptr == public_path)
437     {
438         if (adjustedPtr != NULL)
439             adjustedPtr = const_cast<void*>(info.dst_ptr_leading_to_static_ptr);
440         return true;
441     }
442     return false;
443 }
444 
can_catch_nested(const __shim_type_info * thrown_type) const445 bool __pointer_type_info::can_catch_nested(
446     const __shim_type_info* thrown_type) const
447 {
448   const __pointer_type_info* thrown_pointer_type =
449         dynamic_cast<const __pointer_type_info*>(thrown_type);
450     if (thrown_pointer_type == 0)
451         return false;
452     // bullet 3B
453     if (thrown_pointer_type->__flags & ~__flags)
454         return false;
455     if (is_equal(__pointee, thrown_pointer_type->__pointee, false))
456         return true;
457     // If the pointed to types differ then the catch type must be const
458     // qualified.
459     if (~__flags & __const_mask)
460         return false;
461 
462     // Handle pointer to pointer
463     const __pointer_type_info* nested_pointer_type =
464         dynamic_cast<const __pointer_type_info*>(__pointee);
465     if (nested_pointer_type) {
466         return nested_pointer_type->can_catch_nested(
467             thrown_pointer_type->__pointee);
468     }
469 
470     // Handle pointer to pointer to member
471     const __pointer_to_member_type_info* member_ptr_type =
472         dynamic_cast<const __pointer_to_member_type_info*>(__pointee);
473     if (member_ptr_type) {
474         return member_ptr_type->can_catch_nested(thrown_pointer_type->__pointee);
475     }
476 
477     return false;
478 }
479 
can_catch(const __shim_type_info * thrown_type,void * & adjustedPtr) const480 bool __pointer_to_member_type_info::can_catch(
481     const __shim_type_info* thrown_type, void*& adjustedPtr) const {
482     // bullet 4
483     if (is_equal(thrown_type, &typeid(std::nullptr_t), false)) {
484       // We assume that the pointer to member representation is the same for
485       // all pointers to data members and for all pointers to member functions.
486       struct X {};
487       if (dynamic_cast<const __function_type_info*>(__pointee)) {
488         static int (X::*const null_ptr_rep)() = nullptr;
489         adjustedPtr = const_cast<int (X::**)()>(&null_ptr_rep);
490       } else {
491         static int X::*const null_ptr_rep = nullptr;
492         adjustedPtr = const_cast<int X::**>(&null_ptr_rep);
493       }
494       return true;
495     }
496 
497     // bullet 1
498     if (__pbase_type_info::can_catch(thrown_type, adjustedPtr))
499         return true;
500 
501     const __pointer_to_member_type_info* thrown_pointer_type =
502         dynamic_cast<const __pointer_to_member_type_info*>(thrown_type);
503     if (thrown_pointer_type == 0)
504         return false;
505     if (thrown_pointer_type->__flags & ~__flags & __no_remove_flags_mask)
506         return false;
507     if (__flags & ~thrown_pointer_type->__flags & __no_add_flags_mask)
508         return false;
509     if (!is_equal(__pointee, thrown_pointer_type->__pointee, false))
510         return false;
511     if (is_equal(__context, thrown_pointer_type->__context, false))
512         return true;
513 
514     // [except.handle] does not allow the pointer-to-member conversions mentioned
515     // in [mem.conv] to take place. For this reason we don't check Derived->Base
516     // for Derived->Base conversions.
517 
518     return false;
519 }
520 
can_catch_nested(const __shim_type_info * thrown_type) const521 bool __pointer_to_member_type_info::can_catch_nested(
522     const __shim_type_info* thrown_type) const
523 {
524     const __pointer_to_member_type_info* thrown_member_ptr_type =
525         dynamic_cast<const __pointer_to_member_type_info*>(thrown_type);
526     if (thrown_member_ptr_type == 0)
527         return false;
528     if (~__flags & thrown_member_ptr_type->__flags)
529         return false;
530     if (!is_equal(__pointee, thrown_member_ptr_type->__pointee, false))
531         return false;
532     if (!is_equal(__context, thrown_member_ptr_type->__context, false))
533         return false;
534     return true;
535 }
536 
537 #ifdef __clang__
538 #pragma clang diagnostic pop
539 #endif
540 
541 #pragma GCC visibility pop
542 #pragma GCC visibility push(default)
543 
544 #ifdef __clang__
545 #pragma clang diagnostic push
546 #pragma clang diagnostic ignored "-Wmissing-field-initializers"
547 #endif
548 
549 // __dynamic_cast
550 
551 // static_ptr: pointer to an object of type static_type; nonnull, and since the
552 //   object is polymorphic, *(void**)static_ptr is a virtual table pointer.
553 //   static_ptr is &v in the expression dynamic_cast<T>(v).
554 // static_type: static type of the object pointed to by static_ptr.
555 // dst_type: destination type of the cast (the "T" in "dynamic_cast<T>(v)").
556 // src2dst_offset: a static hint about the location of the
557 //                 source subobject with respect to the complete object;
558 //                 special negative values are:
559 //                     -1: no hint
560 //                     -2: static_type is not a public base of dst_type
561 //                     -3: static_type is a multiple public base type but never a
562 //                         virtual base type
563 //                 otherwise, the static_type type is a unique public nonvirtual
564 //                 base type of dst_type at offset src2dst_offset from the
565 //                 origin of dst_type.
566 //
567 // (dynamic_ptr, dynamic_type) are the run time type of the complete object
568 // referred to by static_ptr and a pointer to it.  These can be found from
569 // static_ptr for polymorphic types.
570 // static_type is guaranteed to be a polymorphic type.
571 //
572 // (dynamic_ptr, dynamic_type) is the root of a DAG that grows upward.  Each
573 // node of the tree represents a base class/object of its parent (or parents) below.
574 // Each node is uniquely represented by a pointer to the object, and a pointer
575 // to a type_info - its type.  Different nodes may have the same pointer and
576 // different nodes may have the same type.  But only one node has a specific
577 // (pointer-value, type) pair.  In C++ two objects of the same type can not
578 // share the same address.
579 //
580 // There are two flavors of nodes which have the type dst_type:
581 //    1.  Those that are derived from (below) (static_ptr, static_type).
582 //    2.  Those that are not derived from (below) (static_ptr, static_type).
583 //
584 // Invariants of the DAG:
585 //
586 // There is at least one path from the root (dynamic_ptr, dynamic_type) to
587 // the node (static_ptr, static_type).  This path may or may not be public.
588 // There may be more than one such path (some public some not).  Such a path may
589 // or may not go through a node having type dst_type.
590 //
591 // No node of type T appears above a node of the same type.  That means that
592 // there is only one node with dynamic_type.  And if dynamic_type == dst_type,
593 // then there is only one dst_type in the DAG.
594 //
595 // No node of type dst_type appears above a node of type static_type.  Such
596 // DAG's are possible in C++, but the compiler computes those dynamic_casts at
597 // compile time, and only calls __dynamic_cast when dst_type lies below
598 // static_type in the DAG.
599 //
600 // dst_type != static_type:  The compiler computes the dynamic_cast in this case too.
601 // dynamic_type != static_type:  The compiler computes the dynamic_cast in this case too.
602 //
603 // Returns:
604 //
605 // If there is exactly one dst_type of flavor 1, and
606 //    If there is a public path from that dst_type to (static_ptr, static_type), or
607 //    If there are 0 dst_types of flavor 2, and there is a public path from
608 //        (dynamic_ptr, dynamic_type) to (static_ptr, static_type) and a public
609 //        path from (dynamic_ptr, dynamic_type) to the one dst_type, then return
610 //        a pointer to that dst_type.
611 // Else if there are 0 dst_types of flavor 1 and exactly 1 dst_type of flavor 2, and
612 //    if there is a public path from (dynamic_ptr, dynamic_type) to
613 //    (static_ptr, static_type) and a public path from (dynamic_ptr, dynamic_type)
614 //    to the one dst_type, then return a pointer to that one dst_type.
615 // Else return nullptr.
616 //
617 // If dynamic_type == dst_type, then the above algorithm collapses to the
618 // following cheaper algorithm:
619 //
620 // If there is a public path from (dynamic_ptr, dynamic_type) to
621 //    (static_ptr, static_type), then return dynamic_ptr.
622 // Else return nullptr.
623 
624 extern "C" _LIBCXXABI_FUNC_VIS void *
__dynamic_cast(const void * static_ptr,const __class_type_info * static_type,const __class_type_info * dst_type,std::ptrdiff_t src2dst_offset)625 __dynamic_cast(const void *static_ptr, const __class_type_info *static_type,
626                const __class_type_info *dst_type,
627                std::ptrdiff_t src2dst_offset) {
628     // Possible future optimization:  Take advantage of src2dst_offset
629     // Currently clang always sets src2dst_offset to -1 (no hint).
630 
631     // Get (dynamic_ptr, dynamic_type) from static_ptr
632     void **vtable = *static_cast<void ** const *>(static_ptr);
633     ptrdiff_t offset_to_derived = reinterpret_cast<ptrdiff_t>(vtable[-2]);
634     const void* dynamic_ptr = static_cast<const char*>(static_ptr) + offset_to_derived;
635     const __class_type_info* dynamic_type = static_cast<const __class_type_info*>(vtable[-1]);
636 
637     // Initialize answer to nullptr.  This will be changed from the search
638     //    results if a non-null answer is found.  Regardless, this is what will
639     //    be returned.
640     const void* dst_ptr = 0;
641     // Initialize info struct for this search.
642     __dynamic_cast_info info = {dst_type, static_ptr, static_type, src2dst_offset, 0};
643 
644     // Find out if we can use a giant short cut in the search
645     if (is_equal(dynamic_type, dst_type, false))
646     {
647         // Using giant short cut.  Add that information to info.
648         info.number_of_dst_type = 1;
649         // Do the  search
650         dynamic_type->search_above_dst(&info, dynamic_ptr, dynamic_ptr, public_path, false);
651 #ifdef _LIBCXX_DYNAMIC_FALLBACK
652         // The following if should always be false because we should definitely
653         //   find (static_ptr, static_type), either on a public or private path
654         if (info.path_dst_ptr_to_static_ptr == unknown)
655         {
656             // We get here only if there is some kind of visibility problem
657             //   in client code.
658             syslog(LOG_ERR, "dynamic_cast error 1: Both of the following type_info's "
659                     "should have public visibility.  At least one of them is hidden. %s"
660                     ", %s.\n", static_type->name(), dynamic_type->name());
661             // Redo the search comparing type_info's using strcmp
662             info = {dst_type, static_ptr, static_type, src2dst_offset, 0};
663             info.number_of_dst_type = 1;
664             dynamic_type->search_above_dst(&info, dynamic_ptr, dynamic_ptr, public_path, true);
665         }
666 #endif  // _LIBCXX_DYNAMIC_FALLBACK
667         // Query the search.
668         if (info.path_dst_ptr_to_static_ptr == public_path)
669             dst_ptr = dynamic_ptr;
670     }
671     else
672     {
673         // Not using giant short cut.  Do the search
674         dynamic_type->search_below_dst(&info, dynamic_ptr, public_path, false);
675  #ifdef _LIBCXX_DYNAMIC_FALLBACK
676         // The following if should always be false because we should definitely
677         //   find (static_ptr, static_type), either on a public or private path
678         if (info.path_dst_ptr_to_static_ptr == unknown &&
679             info.path_dynamic_ptr_to_static_ptr == unknown)
680         {
681             syslog(LOG_ERR, "dynamic_cast error 2: One or more of the following type_info's "
682                             " has hidden visibility.  They should all have public visibility.  "
683                             " %s, %s, %s.\n", static_type->name(), dynamic_type->name(),
684                     dst_type->name());
685             // Redo the search comparing type_info's using strcmp
686             info = {dst_type, static_ptr, static_type, src2dst_offset, 0};
687             dynamic_type->search_below_dst(&info, dynamic_ptr, public_path, true);
688         }
689 #endif  // _LIBCXX_DYNAMIC_FALLBACK
690         // Query the search.
691         switch (info.number_to_static_ptr)
692         {
693         case 0:
694             if (info.number_to_dst_ptr == 1 &&
695                     info.path_dynamic_ptr_to_static_ptr == public_path &&
696                     info.path_dynamic_ptr_to_dst_ptr == public_path)
697                 dst_ptr = info.dst_ptr_not_leading_to_static_ptr;
698             break;
699         case 1:
700             if (info.path_dst_ptr_to_static_ptr == public_path ||
701                    (
702                        info.number_to_dst_ptr == 0 &&
703                        info.path_dynamic_ptr_to_static_ptr == public_path &&
704                        info.path_dynamic_ptr_to_dst_ptr == public_path
705                    )
706                )
707                 dst_ptr = info.dst_ptr_leading_to_static_ptr;
708             break;
709         }
710     }
711     return const_cast<void*>(dst_ptr);
712 }
713 
714 #ifdef __clang__
715 #pragma clang diagnostic pop
716 #endif
717 
718 #pragma GCC visibility pop
719 #pragma GCC visibility push(hidden)
720 
721 // Call this function when you hit a static_type which is a base (above) a dst_type.
722 // Let caller know you hit a static_type.  But only start recording details if
723 // this is (static_ptr, static_type) -- the node we are casting from.
724 // If this is (static_ptr, static_type)
725 //   Record the path (public or not) from the dst_type to here.  There may be
726 //   multiple paths from the same dst_type to here, record the "most public" one.
727 //   Record the dst_ptr as pointing to (static_ptr, static_type).
728 //   If more than one (dst_ptr, dst_type) points to (static_ptr, static_type),
729 //   then mark this dyanmic_cast as ambiguous and stop the search.
730 void
process_static_type_above_dst(__dynamic_cast_info * info,const void * dst_ptr,const void * current_ptr,int path_below) const731 __class_type_info::process_static_type_above_dst(__dynamic_cast_info* info,
732                                                  const void* dst_ptr,
733                                                  const void* current_ptr,
734                                                  int path_below) const
735 {
736     // Record that we found a static_type
737     info->found_any_static_type = true;
738     if (current_ptr == info->static_ptr)
739     {
740         // Record that we found (static_ptr, static_type)
741         info->found_our_static_ptr = true;
742         if (info->dst_ptr_leading_to_static_ptr == 0)
743         {
744             // First time here
745             info->dst_ptr_leading_to_static_ptr = dst_ptr;
746             info->path_dst_ptr_to_static_ptr = path_below;
747             info->number_to_static_ptr = 1;
748             // If there is only one dst_type in the entire tree and the path from
749             //    there to here is public then we are done!
750             if (info->number_of_dst_type == 1 && info->path_dst_ptr_to_static_ptr == public_path)
751                 info->search_done = true;
752         }
753         else if (info->dst_ptr_leading_to_static_ptr == dst_ptr)
754         {
755             // We've been here before.  Update path to "most public"
756             if (info->path_dst_ptr_to_static_ptr == not_public_path)
757                 info->path_dst_ptr_to_static_ptr = path_below;
758             // If there is only one dst_type in the entire tree and the path from
759             //    there to here is public then we are done!
760             if (info->number_of_dst_type == 1 && info->path_dst_ptr_to_static_ptr == public_path)
761                 info->search_done = true;
762         }
763         else
764         {
765             // We've detected an ambiguous cast from (static_ptr, static_type)
766             //   to a dst_type
767             info->number_to_static_ptr += 1;
768             info->search_done = true;
769         }
770     }
771 }
772 
773 // Call this function when you hit a static_type which is not a base (above) a dst_type.
774 // If this is (static_ptr, static_type)
775 //   Record the path (public or not) from (dynamic_ptr, dynamic_type) to here.  There may be
776 //   multiple paths from (dynamic_ptr, dynamic_type) to here, record the "most public" one.
777 void
process_static_type_below_dst(__dynamic_cast_info * info,const void * current_ptr,int path_below) const778 __class_type_info::process_static_type_below_dst(__dynamic_cast_info* info,
779                                                  const void* current_ptr,
780                                                  int path_below) const
781 {
782     if (current_ptr == info->static_ptr)
783     {
784         // Record the most public path from (dynamic_ptr, dynamic_type) to
785         //                                  (static_ptr, static_type)
786         if (info->path_dynamic_ptr_to_static_ptr != public_path)
787             info->path_dynamic_ptr_to_static_ptr = path_below;
788     }
789 }
790 
791 // Call this function when searching below a dst_type node.  This function searches
792 // for a path to (static_ptr, static_type) and for paths to one or more dst_type nodes.
793 // If it finds a static_type node, there is no need to further search base classes
794 // above.
795 // If it finds a dst_type node it should search base classes using search_above_dst
796 // to find out if this dst_type points to (static_ptr, static_type) or not.
797 // Either way, the dst_type is recorded as one of two "flavors":  one that does
798 // or does not point to (static_ptr, static_type).
799 // If this is neither a static_type nor a dst_type node, continue searching
800 // base classes above.
801 // All the hoopla surrounding the search code is doing nothing but looking for
802 // excuses to stop the search prematurely (break out of the for-loop).  That is,
803 // the algorithm below is simply an optimization of this:
804 // void
805 // __vmi_class_type_info::search_below_dst(__dynamic_cast_info* info,
806 //                                         const void* current_ptr,
807 //                                         int path_below) const
808 // {
809 //     typedef const __base_class_type_info* Iter;
810 //     if (this == info->static_type)
811 //         process_static_type_below_dst(info, current_ptr, path_below);
812 //     else if (this == info->dst_type)
813 //     {
814 //         // Record the most public access path that got us here
815 //         if (info->path_dynamic_ptr_to_dst_ptr != public_path)
816 //             info->path_dynamic_ptr_to_dst_ptr = path_below;
817 //         bool does_dst_type_point_to_our_static_type = false;
818 //         for (Iter p = __base_info, e= __base_info + __base_count; p < e; ++p)
819 //         {
820 //             p->search_above_dst(info, current_ptr, current_ptr, public_path);
821 //             if (info->found_our_static_ptr)
822 //                 does_dst_type_point_to_our_static_type = true;
823 //             // break out early here if you can detect it doesn't matter if you do
824 //         }
825 //         if (!does_dst_type_point_to_our_static_type)
826 //         {
827 //             // We found a dst_type that doesn't point to (static_ptr, static_type)
828 //             // So record the address of this dst_ptr and increment the
829 //             // count of the number of such dst_types found in the tree.
830 //             info->dst_ptr_not_leading_to_static_ptr = current_ptr;
831 //             info->number_to_dst_ptr += 1;
832 //         }
833 //     }
834 //     else
835 //     {
836 //         // This is not a static_type and not a dst_type.
837 //         for (Iter p = __base_info, e = __base_info + __base_count; p < e; ++p)
838 //         {
839 //             p->search_below_dst(info, current_ptr, public_path);
840 //             // break out early here if you can detect it doesn't matter if you do
841 //         }
842 //     }
843 // }
844 void
search_below_dst(__dynamic_cast_info * info,const void * current_ptr,int path_below,bool use_strcmp) const845 __vmi_class_type_info::search_below_dst(__dynamic_cast_info* info,
846                                         const void* current_ptr,
847                                         int path_below,
848                                         bool use_strcmp) const
849 {
850     typedef const __base_class_type_info* Iter;
851     if (is_equal(this, info->static_type, use_strcmp))
852         process_static_type_below_dst(info, current_ptr, path_below);
853     else if (is_equal(this, info->dst_type, use_strcmp))
854     {
855         // We've been here before if we've recorded current_ptr in one of these
856         //   two places:
857         if (current_ptr == info->dst_ptr_leading_to_static_ptr ||
858             current_ptr == info->dst_ptr_not_leading_to_static_ptr)
859         {
860             // We've seen this node before, and therefore have already searched
861             // its base classes above.
862             //  Update path to here that is "most public".
863             if (path_below == public_path)
864                 info->path_dynamic_ptr_to_dst_ptr = public_path;
865         }
866         else  // We have haven't been here before
867         {
868             // Record the access path that got us here
869             //   If there is more than one dst_type this path doesn't matter.
870             info->path_dynamic_ptr_to_dst_ptr = path_below;
871             // Only search above here if dst_type derives from static_type, or
872             //    if it is unknown if dst_type derives from static_type.
873             if (info->is_dst_type_derived_from_static_type != no)
874             {
875                 // Set up flags to record results from all base classes
876                 bool is_dst_type_derived_from_static_type = false;
877                 bool does_dst_type_point_to_our_static_type = false;
878                 // We've found a dst_type with a potentially public path to here.
879                 // We have to assume the path is public because it may become
880                 //   public later (if we get back to here with a public path).
881                 // We can stop looking above if:
882                 //    1.  We've found a public path to (static_ptr, static_type).
883                 //    2.  We've found an ambiguous cast from (static_ptr, static_type) to a dst_type.
884                 //        This is detected at the (static_ptr, static_type).
885                 //    3.  We can prove that there is no public path to (static_ptr, static_type)
886                 //        above here.
887                 const Iter e = __base_info + __base_count;
888                 for (Iter p = __base_info; p < e; ++p)
889                 {
890                     // Zero out found flags
891                     info->found_our_static_ptr = false;
892                     info->found_any_static_type = false;
893                     p->search_above_dst(info, current_ptr, current_ptr, public_path, use_strcmp);
894                     if (info->search_done)
895                         break;
896                     if (info->found_any_static_type)
897                     {
898                         is_dst_type_derived_from_static_type = true;
899                         if (info->found_our_static_ptr)
900                         {
901                             does_dst_type_point_to_our_static_type = true;
902                             // If we found what we're looking for, stop looking above.
903                             if (info->path_dst_ptr_to_static_ptr == public_path)
904                                 break;
905                             // We found a private path to (static_ptr, static_type)
906                             //   If there is no diamond then there is only one path
907                             //   to (static_ptr, static_type) and we just found it.
908                             if (!(__flags & __diamond_shaped_mask))
909                                 break;
910                         }
911                         else
912                         {
913                             // If we found a static_type that isn't the one we're looking
914                             //    for, and if there are no repeated types above here,
915                             //    then stop looking.
916                             if (!(__flags & __non_diamond_repeat_mask))
917                                 break;
918                         }
919                     }
920                 }
921                 if (!does_dst_type_point_to_our_static_type)
922                 {
923                     // We found a dst_type that doesn't point to (static_ptr, static_type)
924                     // So record the address of this dst_ptr and increment the
925                     // count of the number of such dst_types found in the tree.
926                     info->dst_ptr_not_leading_to_static_ptr = current_ptr;
927                     info->number_to_dst_ptr += 1;
928                     // If there exists another dst with a private path to
929                     //    (static_ptr, static_type), then the cast from
930                     //     (dynamic_ptr, dynamic_type) to dst_type is now ambiguous,
931                     //      so stop search.
932                     if (info->number_to_static_ptr == 1 &&
933                             info->path_dst_ptr_to_static_ptr == not_public_path)
934                         info->search_done = true;
935                 }
936                 // If we found no static_type,s then dst_type doesn't derive
937                 //   from static_type, else it does.  Record this result so that
938                 //   next time we hit a dst_type we will know not to search above
939                 //   it if it doesn't derive from static_type.
940                 if (is_dst_type_derived_from_static_type)
941                     info->is_dst_type_derived_from_static_type = yes;
942                 else
943                     info->is_dst_type_derived_from_static_type = no;
944             }
945         }
946     }
947     else
948     {
949         // This is not a static_type and not a dst_type.
950         const Iter e = __base_info + __base_count;
951         Iter p = __base_info;
952         p->search_below_dst(info, current_ptr, path_below, use_strcmp);
953         if (++p < e)
954         {
955             if ((__flags & __diamond_shaped_mask) || info->number_to_static_ptr == 1)
956             {
957                 // If there are multiple paths to a base above from here, or if
958                 //    a dst_type pointing to (static_ptr, static_type) has been found,
959                 //    then there is no way to break out of this loop early unless
960                 //    something below detects the search is done.
961                 do
962                 {
963                     if (info->search_done)
964                         break;
965                     p->search_below_dst(info, current_ptr, path_below, use_strcmp);
966                 } while (++p < e);
967             }
968             else if (__flags & __non_diamond_repeat_mask)
969             {
970                 // There are not multiple paths to any base class from here and a
971                 //   dst_type pointing to (static_ptr, static_type) has not yet been
972                 //   found.
973                 do
974                 {
975                     if (info->search_done)
976                         break;
977                     // If we just found a dst_type with a public path to (static_ptr, static_type),
978                     //    then the only reason to continue the search is to make sure
979                     //    no other dst_type points to (static_ptr, static_type).
980                     //    If !diamond, then we don't need to search here.
981                     if (info->number_to_static_ptr == 1 &&
982                               info->path_dst_ptr_to_static_ptr == public_path)
983                         break;
984                     p->search_below_dst(info, current_ptr, path_below, use_strcmp);
985                 } while (++p < e);
986             }
987             else
988             {
989                 // There are no repeated types above this node.
990                 // There are no nodes with multiple parents above this node.
991                 // no dst_type has been found to (static_ptr, static_type)
992                 do
993                 {
994                     if (info->search_done)
995                         break;
996                     // If we just found a dst_type with a public path to (static_ptr, static_type),
997                     //    then the only reason to continue the search is to make sure sure
998                     //    no other dst_type points to (static_ptr, static_type).
999                     //    If !diamond, then we don't need to search here.
1000                     // if we just found a dst_type with a private path to (static_ptr, static_type),
1001                     //    then we're only looking for a public path to (static_ptr, static_type)
1002                     //    and to check for other dst_types.
1003                     //    If !diamond & !repeat, then there is not a pointer to (static_ptr, static_type)
1004                     //    and not a dst_type under here.
1005                     if (info->number_to_static_ptr == 1)
1006                         break;
1007                     p->search_below_dst(info, current_ptr, path_below, use_strcmp);
1008                 } while (++p < e);
1009             }
1010         }
1011     }
1012 }
1013 
1014 // This is the same algorithm as __vmi_class_type_info::search_below_dst but
1015 //   simplified to the case that there is only a single base class.
1016 void
search_below_dst(__dynamic_cast_info * info,const void * current_ptr,int path_below,bool use_strcmp) const1017 __si_class_type_info::search_below_dst(__dynamic_cast_info* info,
1018                                        const void* current_ptr,
1019                                        int path_below,
1020                                        bool use_strcmp) const
1021 {
1022     if (is_equal(this, info->static_type, use_strcmp))
1023         process_static_type_below_dst(info, current_ptr, path_below);
1024     else if (is_equal(this, info->dst_type, use_strcmp))
1025     {
1026         // We've been here before if we've recorded current_ptr in one of these
1027         //   two places:
1028         if (current_ptr == info->dst_ptr_leading_to_static_ptr ||
1029             current_ptr == info->dst_ptr_not_leading_to_static_ptr)
1030         {
1031             // We've seen this node before, and therefore have already searched
1032             // its base classes above.
1033             //  Update path to here that is "most public".
1034             if (path_below == public_path)
1035                 info->path_dynamic_ptr_to_dst_ptr = public_path;
1036         }
1037         else  // We have haven't been here before
1038         {
1039             // Record the access path that got us here
1040             //   If there is more than one dst_type this path doesn't matter.
1041             info->path_dynamic_ptr_to_dst_ptr = path_below;
1042             // Only search above here if dst_type derives from static_type, or
1043             //    if it is unknown if dst_type derives from static_type.
1044             if (info->is_dst_type_derived_from_static_type != no)
1045             {
1046                 // Set up flags to record results from all base classes
1047                 bool is_dst_type_derived_from_static_type = false;
1048                 bool does_dst_type_point_to_our_static_type = false;
1049                 // Zero out found flags
1050                 info->found_our_static_ptr = false;
1051                 info->found_any_static_type = false;
1052                 __base_type->search_above_dst(info, current_ptr, current_ptr, public_path, use_strcmp);
1053                 if (info->found_any_static_type)
1054                 {
1055                     is_dst_type_derived_from_static_type = true;
1056                     if (info->found_our_static_ptr)
1057                         does_dst_type_point_to_our_static_type = true;
1058                 }
1059                 if (!does_dst_type_point_to_our_static_type)
1060                 {
1061                     // We found a dst_type that doesn't point to (static_ptr, static_type)
1062                     // So record the address of this dst_ptr and increment the
1063                     // count of the number of such dst_types found in the tree.
1064                     info->dst_ptr_not_leading_to_static_ptr = current_ptr;
1065                     info->number_to_dst_ptr += 1;
1066                     // If there exists another dst with a private path to
1067                     //    (static_ptr, static_type), then the cast from
1068                     //     (dynamic_ptr, dynamic_type) to dst_type is now ambiguous.
1069                     if (info->number_to_static_ptr == 1 &&
1070                             info->path_dst_ptr_to_static_ptr == not_public_path)
1071                         info->search_done = true;
1072                 }
1073                 // If we found no static_type,s then dst_type doesn't derive
1074                 //   from static_type, else it does.  Record this result so that
1075                 //   next time we hit a dst_type we will know not to search above
1076                 //   it if it doesn't derive from static_type.
1077                 if (is_dst_type_derived_from_static_type)
1078                     info->is_dst_type_derived_from_static_type = yes;
1079                 else
1080                     info->is_dst_type_derived_from_static_type = no;
1081             }
1082         }
1083     }
1084     else
1085     {
1086         // This is not a static_type and not a dst_type
1087         __base_type->search_below_dst(info, current_ptr, path_below, use_strcmp);
1088     }
1089 }
1090 
1091 // This is the same algorithm as __vmi_class_type_info::search_below_dst but
1092 //   simplified to the case that there is no base class.
1093 void
search_below_dst(__dynamic_cast_info * info,const void * current_ptr,int path_below,bool use_strcmp) const1094 __class_type_info::search_below_dst(__dynamic_cast_info* info,
1095                                     const void* current_ptr,
1096                                     int path_below,
1097                                     bool use_strcmp) const
1098 {
1099     if (is_equal(this, info->static_type, use_strcmp))
1100         process_static_type_below_dst(info, current_ptr, path_below);
1101     else if (is_equal(this, info->dst_type, use_strcmp))
1102     {
1103         // We've been here before if we've recorded current_ptr in one of these
1104         //   two places:
1105         if (current_ptr == info->dst_ptr_leading_to_static_ptr ||
1106             current_ptr == info->dst_ptr_not_leading_to_static_ptr)
1107         {
1108             // We've seen this node before, and therefore have already searched
1109             // its base classes above.
1110             //  Update path to here that is "most public".
1111             if (path_below == public_path)
1112                 info->path_dynamic_ptr_to_dst_ptr = public_path;
1113         }
1114         else  // We have haven't been here before
1115         {
1116             // Record the access path that got us here
1117             //   If there is more than one dst_type this path doesn't matter.
1118             info->path_dynamic_ptr_to_dst_ptr = path_below;
1119             // We found a dst_type that doesn't point to (static_ptr, static_type)
1120             // So record the address of this dst_ptr and increment the
1121             // count of the number of such dst_types found in the tree.
1122             info->dst_ptr_not_leading_to_static_ptr = current_ptr;
1123             info->number_to_dst_ptr += 1;
1124             // If there exists another dst with a private path to
1125             //    (static_ptr, static_type), then the cast from
1126             //     (dynamic_ptr, dynamic_type) to dst_type is now ambiguous.
1127             if (info->number_to_static_ptr == 1 &&
1128                     info->path_dst_ptr_to_static_ptr == not_public_path)
1129                 info->search_done = true;
1130             // We found that dst_type does not derive from static_type
1131             info->is_dst_type_derived_from_static_type = no;
1132         }
1133     }
1134 }
1135 
1136 // Call this function when searching above a dst_type node.  This function searches
1137 // for a public path to (static_ptr, static_type).
1138 // This function is guaranteed not to find a node of type dst_type.
1139 // Theoretically this is a very simple function which just stops if it finds a
1140 // static_type node:  All the hoopla surrounding the search code is doing
1141 // nothing but looking for excuses to stop the search prematurely (break out of
1142 // the for-loop).  That is, the algorithm below is simply an optimization of this:
1143 // void
1144 // __vmi_class_type_info::search_above_dst(__dynamic_cast_info* info,
1145 //                                         const void* dst_ptr,
1146 //                                         const void* current_ptr,
1147 //                                         int path_below) const
1148 // {
1149 //     if (this == info->static_type)
1150 //         process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
1151 //     else
1152 //     {
1153 //         typedef const __base_class_type_info* Iter;
1154 //         // This is not a static_type and not a dst_type
1155 //         for (Iter p = __base_info, e = __base_info + __base_count; p < e; ++p)
1156 //         {
1157 //             p->search_above_dst(info, dst_ptr, current_ptr, public_path);
1158 //             // break out early here if you can detect it doesn't matter if you do
1159 //         }
1160 //     }
1161 // }
1162 void
search_above_dst(__dynamic_cast_info * info,const void * dst_ptr,const void * current_ptr,int path_below,bool use_strcmp) const1163 __vmi_class_type_info::search_above_dst(__dynamic_cast_info* info,
1164                                         const void* dst_ptr,
1165                                         const void* current_ptr,
1166                                         int path_below,
1167                                         bool use_strcmp) const
1168 {
1169     if (is_equal(this, info->static_type, use_strcmp))
1170         process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
1171     else
1172     {
1173         typedef const __base_class_type_info* Iter;
1174         // This is not a static_type and not a dst_type
1175         // Save flags so they can be restored when returning to nodes below.
1176         bool found_our_static_ptr = info->found_our_static_ptr;
1177         bool found_any_static_type = info->found_any_static_type;
1178         // We've found a dst_type below with a path to here.  If the path
1179         //    to here is not public, there may be another path to here that
1180         //    is public.  So we have to assume that the path to here is public.
1181         //  We can stop looking above if:
1182         //    1.  We've found a public path to (static_ptr, static_type).
1183         //    2.  We've found an ambiguous cast from (static_ptr, static_type) to a dst_type.
1184         //        This is detected at the (static_ptr, static_type).
1185         //    3.  We can prove that there is no public path to (static_ptr, static_type)
1186         //        above here.
1187         const Iter e = __base_info + __base_count;
1188         Iter p = __base_info;
1189         // Zero out found flags
1190         info->found_our_static_ptr = false;
1191         info->found_any_static_type = false;
1192         p->search_above_dst(info, dst_ptr, current_ptr, path_below, use_strcmp);
1193         if (++p < e)
1194         {
1195             do
1196             {
1197                 if (info->search_done)
1198                     break;
1199                 if (info->found_our_static_ptr)
1200                 {
1201                     // If we found what we're looking for, stop looking above.
1202                     if (info->path_dst_ptr_to_static_ptr == public_path)
1203                         break;
1204                     // We found a private path to (static_ptr, static_type)
1205                     //   If there is no diamond then there is only one path
1206                     //   to (static_ptr, static_type) from here and we just found it.
1207                     if (!(__flags & __diamond_shaped_mask))
1208                         break;
1209                 }
1210                 else if (info->found_any_static_type)
1211                 {
1212                     // If we found a static_type that isn't the one we're looking
1213                     //    for, and if there are no repeated types above here,
1214                     //    then stop looking.
1215                     if (!(__flags & __non_diamond_repeat_mask))
1216                         break;
1217                 }
1218                 // Zero out found flags
1219                 info->found_our_static_ptr = false;
1220                 info->found_any_static_type = false;
1221                 p->search_above_dst(info, dst_ptr, current_ptr, path_below, use_strcmp);
1222             } while (++p < e);
1223         }
1224         // Restore flags
1225         info->found_our_static_ptr = found_our_static_ptr;
1226         info->found_any_static_type = found_any_static_type;
1227     }
1228 }
1229 
1230 // This is the same algorithm as __vmi_class_type_info::search_above_dst but
1231 //   simplified to the case that there is only a single base class.
1232 void
search_above_dst(__dynamic_cast_info * info,const void * dst_ptr,const void * current_ptr,int path_below,bool use_strcmp) const1233 __si_class_type_info::search_above_dst(__dynamic_cast_info* info,
1234                                        const void* dst_ptr,
1235                                        const void* current_ptr,
1236                                        int path_below,
1237                                        bool use_strcmp) const
1238 {
1239     if (is_equal(this, info->static_type, use_strcmp))
1240         process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
1241     else
1242         __base_type->search_above_dst(info, dst_ptr, current_ptr, path_below, use_strcmp);
1243 }
1244 
1245 // This is the same algorithm as __vmi_class_type_info::search_above_dst but
1246 //   simplified to the case that there is no base class.
1247 void
search_above_dst(__dynamic_cast_info * info,const void * dst_ptr,const void * current_ptr,int path_below,bool use_strcmp) const1248 __class_type_info::search_above_dst(__dynamic_cast_info* info,
1249                                     const void* dst_ptr,
1250                                     const void* current_ptr,
1251                                     int path_below,
1252                                     bool use_strcmp) const
1253 {
1254     if (is_equal(this, info->static_type, use_strcmp))
1255         process_static_type_above_dst(info, dst_ptr, current_ptr, path_below);
1256 }
1257 
1258 // The search functions for __base_class_type_info are simply convenience
1259 //   functions for adjusting the current_ptr and path_below as the search is
1260 //   passed up to the base class node.
1261 
1262 void
search_above_dst(__dynamic_cast_info * info,const void * dst_ptr,const void * current_ptr,int path_below,bool use_strcmp) const1263 __base_class_type_info::search_above_dst(__dynamic_cast_info* info,
1264                                          const void* dst_ptr,
1265                                          const void* current_ptr,
1266                                          int path_below,
1267                                          bool use_strcmp) const
1268 {
1269     ptrdiff_t offset_to_base = __offset_flags >> __offset_shift;
1270     if (__offset_flags & __virtual_mask)
1271     {
1272         const char* vtable = *static_cast<const char*const*>(current_ptr);
1273         offset_to_base = *reinterpret_cast<const ptrdiff_t*>(vtable + offset_to_base);
1274     }
1275     __base_type->search_above_dst(info, dst_ptr,
1276                                   static_cast<const char*>(current_ptr) + offset_to_base,
1277                                   (__offset_flags & __public_mask) ?
1278                                       path_below :
1279                                       not_public_path,
1280                                   use_strcmp);
1281 }
1282 
1283 void
search_below_dst(__dynamic_cast_info * info,const void * current_ptr,int path_below,bool use_strcmp) const1284 __base_class_type_info::search_below_dst(__dynamic_cast_info* info,
1285                                          const void* current_ptr,
1286                                          int path_below,
1287                                          bool use_strcmp) const
1288 {
1289     ptrdiff_t offset_to_base = __offset_flags >> __offset_shift;
1290     if (__offset_flags & __virtual_mask)
1291     {
1292         const char* vtable = *static_cast<const char*const*>(current_ptr);
1293         offset_to_base = *reinterpret_cast<const ptrdiff_t*>(vtable + offset_to_base);
1294     }
1295     __base_type->search_below_dst(info,
1296                                   static_cast<const char*>(current_ptr) + offset_to_base,
1297                                   (__offset_flags & __public_mask) ?
1298                                       path_below :
1299                                       not_public_path,
1300                                   use_strcmp);
1301 }
1302 
1303 #pragma GCC visibility pop
1304 
1305 }  // __cxxabiv1
1306