1//===----------------------------------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//
8// This file implements the "Array Construction and Destruction APIs"
9// https://itanium-cxx-abi.github.io/cxx-abi/abi.html#array-ctor
10//
11//===----------------------------------------------------------------------===//
12
13#include "cxxabi.h"
14#include "__cxxabi_config.h"
15
16#include <exception> // for std::terminate
17#include <new> // for std::bad_array_new_length
18
19#include "abort_message.h"
20
21#ifndef __has_builtin
22#define __has_builtin(x) 0
23#endif
24
25namespace __cxxabiv1 {
26
27//
28// Helper routines and classes
29//
30
31namespace {
32 inline static size_t __get_element_count ( void *p ) {
33 return static_cast <size_t *> (p)[-1];
34 }
35
36 inline static void __set_element_count ( void *p, size_t element_count ) {
37 static_cast <size_t *> (p)[-1] = element_count;
38 }
39
40
41// A pair of classes to simplify exception handling and control flow.
42// They get passed a block of memory in the constructor, and unless the
43// 'release' method is called, they deallocate the memory in the destructor.
44// Preferred usage is to allocate some memory, attach it to one of these objects,
45// and then, when all the operations to set up the memory block have succeeded,
46// call 'release'. If any of the setup operations fail, or an exception is
47// thrown, then the block is automatically deallocated.
48//
49// The only difference between these two classes is the signature for the
50// deallocation function (to match new2/new3 and delete2/delete3.
51 class st_heap_block2 {
52 public:
53 typedef void (*dealloc_f)(void *);
54
55 st_heap_block2 ( dealloc_f dealloc, void *ptr )
56 : dealloc_ ( dealloc ), ptr_ ( ptr ), enabled_ ( true ) {}
57 ~st_heap_block2 () { if ( enabled_ ) dealloc_ ( ptr_ ) ; }
58 void release () { enabled_ = false; }
59
60 private:
61 dealloc_f dealloc_;
62 void *ptr_;
63 bool enabled_;
64 };
65
66 class st_heap_block3 {
67 public:
68 typedef void (*dealloc_f)(void *, size_t);
69
70 st_heap_block3 ( dealloc_f dealloc, void *ptr, size_t size )
71 : dealloc_ ( dealloc ), ptr_ ( ptr ), size_ ( size ), enabled_ ( true ) {}
72 ~st_heap_block3 () { if ( enabled_ ) dealloc_ ( ptr_, size_ ) ; }
73 void release () { enabled_ = false; }
74
75 private:
76 dealloc_f dealloc_;
77 void *ptr_;
78 size_t size_;
79 bool enabled_;
80 };
81
82 class st_cxa_cleanup {
83 public:
84 typedef void (*destruct_f)(void *);
85
86 st_cxa_cleanup ( void *ptr, size_t &idx, size_t element_size, destruct_f destructor )
87 : ptr_ ( ptr ), idx_ ( idx ), element_size_ ( element_size ),
88 destructor_ ( destructor ), enabled_ ( true ) {}
89 ~st_cxa_cleanup () {
90 if ( enabled_ )
91 __cxa_vec_cleanup ( array_address: ptr_, element_count: idx_, s: element_size_, destructor: destructor_ );
92 }
93
94 void release () { enabled_ = false; }
95
96 private:
97 void *ptr_;
98 size_t &idx_;
99 size_t element_size_;
100 destruct_f destructor_;
101 bool enabled_;
102 };
103
104 class st_terminate {
105 public:
106 st_terminate ( bool enabled = true ) : enabled_ ( enabled ) {}
107 ~st_terminate () { if ( enabled_ ) std::terminate (); }
108 void release () { enabled_ = false; }
109 private:
110 bool enabled_ ;
111 };
112}
113
114//
115// Externally visible routines
116//
117
118namespace {
119_LIBCXXABI_NORETURN
120void throw_bad_array_new_length() {
121#ifndef _LIBCXXABI_NO_EXCEPTIONS
122 throw std::bad_array_new_length();
123#else
124 abort_message("__cxa_vec_new failed to allocate memory");
125#endif
126}
127
128bool mul_overflow(size_t x, size_t y, size_t *res) {
129#if (defined(_LIBCXXABI_COMPILER_CLANG) && __has_builtin(__builtin_mul_overflow)) \
130 || defined(_LIBCXXABI_COMPILER_GCC)
131 return __builtin_mul_overflow(x, y, res);
132#else
133 *res = x * y;
134 return x && ((*res / x) != y);
135#endif
136}
137
138bool add_overflow(size_t x, size_t y, size_t *res) {
139#if (defined(_LIBCXXABI_COMPILER_CLANG) && __has_builtin(__builtin_add_overflow)) \
140 || defined(_LIBCXXABI_COMPILER_GCC)
141 return __builtin_add_overflow(x, y, res);
142#else
143 *res = x + y;
144 return *res < y;
145#endif
146}
147
148size_t calculate_allocation_size_or_throw(size_t element_count,
149 size_t element_size,
150 size_t padding_size) {
151 size_t element_heap_size;
152 if (mul_overflow(x: element_count, y: element_size, res: &element_heap_size))
153 throw_bad_array_new_length();
154
155 size_t allocation_size;
156 if (add_overflow(x: element_heap_size, y: padding_size, res: &allocation_size))
157 throw_bad_array_new_length();
158
159 return allocation_size;
160}
161
162} // namespace
163
164extern "C" {
165
166// Equivalent to
167//
168// __cxa_vec_new2(element_count, element_size, padding_size, constructor,
169// destructor, &::operator new[], &::operator delete[])
170_LIBCXXABI_FUNC_VIS void *
171__cxa_vec_new(size_t element_count, size_t element_size, size_t padding_size,
172 void (*constructor)(void *), void (*destructor)(void *)) {
173 return __cxa_vec_new2 ( element_count: element_count, element_size: element_size, padding_size: padding_size,
174 constructor: constructor, destructor: destructor, alloc: &::operator new [], dealloc: &::operator delete [] );
175}
176
177
178// Given the number and size of elements for an array and the non-negative
179// size of prefix padding for a cookie, allocate space (using alloc) for
180// the array preceded by the specified padding, initialize the cookie if
181// the padding is non-zero, and call the given constructor on each element.
182// Return the address of the array proper, after the padding.
183//
184// If alloc throws an exception, rethrow the exception. If alloc returns
185// NULL, return NULL. If the constructor throws an exception, call
186// destructor for any already constructed elements, and rethrow the
187// exception. If the destructor throws an exception, call std::terminate.
188//
189// The constructor may be NULL, in which case it must not be called. If the
190// padding_size is zero, the destructor may be NULL; in that case it must
191// not be called.
192//
193// Neither alloc nor dealloc may be NULL.
194_LIBCXXABI_FUNC_VIS void *
195__cxa_vec_new2(size_t element_count, size_t element_size, size_t padding_size,
196 void (*constructor)(void *), void (*destructor)(void *),
197 void *(*alloc)(size_t), void (*dealloc)(void *)) {
198 const size_t heap_size = calculate_allocation_size_or_throw(
199 element_count, element_size, padding_size);
200 char* const heap_block = static_cast<char*>(alloc(heap_size));
201 char* vec_base = heap_block;
202
203 if (NULL != vec_base) {
204 st_heap_block2 heap(dealloc, heap_block);
205
206 // put the padding before the array elements
207 if ( 0 != padding_size ) {
208 vec_base += padding_size;
209 __set_element_count ( p: vec_base, element_count );
210 }
211
212 // Construct the elements
213 __cxa_vec_ctor ( array_address: vec_base, element_count: element_count, element_size: element_size, constructor: constructor, destructor: destructor );
214 heap.release (); // We're good!
215 }
216
217 return vec_base;
218}
219
220
221// Same as __cxa_vec_new2 except that the deallocation function takes both
222// the object address and its size.
223_LIBCXXABI_FUNC_VIS void *
224__cxa_vec_new3(size_t element_count, size_t element_size, size_t padding_size,
225 void (*constructor)(void *), void (*destructor)(void *),
226 void *(*alloc)(size_t), void (*dealloc)(void *, size_t)) {
227 const size_t heap_size = calculate_allocation_size_or_throw(
228 element_count, element_size, padding_size);
229 char* const heap_block = static_cast<char*>(alloc(heap_size));
230 char* vec_base = heap_block;
231
232 if (NULL != vec_base) {
233 st_heap_block3 heap(dealloc, heap_block, heap_size);
234
235 // put the padding before the array elements
236 if ( 0 != padding_size ) {
237 vec_base += padding_size;
238 __set_element_count ( p: vec_base, element_count );
239 }
240
241 // Construct the elements
242 __cxa_vec_ctor ( array_address: vec_base, element_count: element_count, element_size: element_size, constructor: constructor, destructor: destructor );
243 heap.release (); // We're good!
244 }
245
246 return vec_base;
247}
248
249
250// Given the (data) addresses of a destination and a source array, an
251// element count and an element size, call the given copy constructor to
252// copy each element from the source array to the destination array. The
253// copy constructor's arguments are the destination address and source
254// address, respectively. If an exception occurs, call the given destructor
255// (if non-NULL) on each copied element and rethrow. If the destructor
256// throws an exception, call terminate(). The constructor and or destructor
257// pointers may be NULL. If either is NULL, no action is taken when it
258// would have been called.
259
260_LIBCXXABI_FUNC_VIS void __cxa_vec_cctor(void *dest_array, void *src_array,
261 size_t element_count,
262 size_t element_size,
263 void (*constructor)(void *, void *),
264 void (*destructor)(void *)) {
265 if ( NULL != constructor ) {
266 size_t idx = 0;
267 char *src_ptr = static_cast<char *>(src_array);
268 char *dest_ptr = static_cast<char *>(dest_array);
269 st_cxa_cleanup cleanup ( dest_array, idx, element_size, destructor );
270
271 for ( idx = 0; idx < element_count;
272 ++idx, src_ptr += element_size, dest_ptr += element_size )
273 constructor ( dest_ptr, src_ptr );
274 cleanup.release (); // We're good!
275 }
276}
277
278
279// Given the (data) address of an array, not including any cookie padding,
280// and the number and size of its elements, call the given constructor on
281// each element. If the constructor throws an exception, call the given
282// destructor for any already-constructed elements, and rethrow the
283// exception. If the destructor throws an exception, call terminate(). The
284// constructor and/or destructor pointers may be NULL. If either is NULL,
285// no action is taken when it would have been called.
286_LIBCXXABI_FUNC_VIS void
287__cxa_vec_ctor(void *array_address, size_t element_count, size_t element_size,
288 void (*constructor)(void *), void (*destructor)(void *)) {
289 if ( NULL != constructor ) {
290 size_t idx;
291 char *ptr = static_cast <char *> ( array_address );
292 st_cxa_cleanup cleanup ( array_address, idx, element_size, destructor );
293
294 // Construct the elements
295 for ( idx = 0; idx < element_count; ++idx, ptr += element_size )
296 constructor ( ptr );
297 cleanup.release (); // We're good!
298 }
299}
300
301// Given the (data) address of an array, the number of elements, and the
302// size of its elements, call the given destructor on each element. If the
303// destructor throws an exception, rethrow after destroying the remaining
304// elements if possible. If the destructor throws a second exception, call
305// terminate(). The destructor pointer may be NULL, in which case this
306// routine does nothing.
307_LIBCXXABI_FUNC_VIS void __cxa_vec_dtor(void *array_address,
308 size_t element_count,
309 size_t element_size,
310 void (*destructor)(void *)) {
311 if ( NULL != destructor ) {
312 char *ptr = static_cast <char *> (array_address);
313 size_t idx = element_count;
314 st_cxa_cleanup cleanup ( array_address, idx, element_size, destructor );
315 {
316 st_terminate exception_guard (__cxa_uncaught_exception ());
317 ptr += element_count * element_size; // one past the last element
318
319 while ( idx-- > 0 ) {
320 ptr -= element_size;
321 destructor ( ptr );
322 }
323 exception_guard.release (); // We're good !
324 }
325 cleanup.release (); // We're still good!
326 }
327}
328
329// Given the (data) address of an array, the number of elements, and the
330// size of its elements, call the given destructor on each element. If the
331// destructor throws an exception, call terminate(). The destructor pointer
332// may be NULL, in which case this routine does nothing.
333_LIBCXXABI_FUNC_VIS void __cxa_vec_cleanup(void *array_address,
334 size_t element_count,
335 size_t element_size,
336 void (*destructor)(void *)) {
337 if ( NULL != destructor ) {
338 char *ptr = static_cast <char *> (array_address);
339 size_t idx = element_count;
340 st_terminate exception_guard;
341
342 ptr += element_count * element_size; // one past the last element
343 while ( idx-- > 0 ) {
344 ptr -= element_size;
345 destructor ( ptr );
346 }
347 exception_guard.release (); // We're done!
348 }
349}
350
351
352// If the array_address is NULL, return immediately. Otherwise, given the
353// (data) address of an array, the non-negative size of prefix padding for
354// the cookie, and the size of its elements, call the given destructor on
355// each element, using the cookie to determine the number of elements, and
356// then delete the space by calling ::operator delete[](void *). If the
357// destructor throws an exception, rethrow after (a) destroying the
358// remaining elements, and (b) deallocating the storage. If the destructor
359// throws a second exception, call terminate(). If padding_size is 0, the
360// destructor pointer must be NULL. If the destructor pointer is NULL, no
361// destructor call is to be made.
362//
363// The intent of this function is to permit an implementation to call this
364// function when confronted with an expression of the form delete[] p in
365// the source code, provided that the default deallocation function can be
366// used. Therefore, the semantics of this function are consistent with
367// those required by the standard. The requirement that the deallocation
368// function be called even if the destructor throws an exception derives
369// from the resolution to DR 353 to the C++ standard, which was adopted in
370// April, 2003.
371_LIBCXXABI_FUNC_VIS void __cxa_vec_delete(void *array_address,
372 size_t element_size,
373 size_t padding_size,
374 void (*destructor)(void *)) {
375 __cxa_vec_delete2 ( array_address: array_address, element_size: element_size, padding_size: padding_size,
376 destructor: destructor, dealloc: &::operator delete [] );
377}
378
379// Same as __cxa_vec_delete, except that the given function is used for
380// deallocation instead of the default delete function. If dealloc throws
381// an exception, the result is undefined. The dealloc pointer may not be
382// NULL.
383_LIBCXXABI_FUNC_VIS void
384__cxa_vec_delete2(void *array_address, size_t element_size, size_t padding_size,
385 void (*destructor)(void *), void (*dealloc)(void *)) {
386 if ( NULL != array_address ) {
387 char *vec_base = static_cast <char *> (array_address);
388 char *heap_block = vec_base - padding_size;
389 st_heap_block2 heap ( dealloc, heap_block );
390
391 if ( 0 != padding_size && NULL != destructor ) // call the destructors
392 __cxa_vec_dtor ( array_address: array_address, element_count: __get_element_count ( p: vec_base ),
393 element_size: element_size, destructor: destructor );
394 }
395}
396
397
398// Same as __cxa_vec_delete, except that the given function is used for
399// deallocation instead of the default delete function. The deallocation
400// function takes both the object address and its size. If dealloc throws
401// an exception, the result is undefined. The dealloc pointer may not be
402// NULL.
403_LIBCXXABI_FUNC_VIS void
404__cxa_vec_delete3(void *array_address, size_t element_size, size_t padding_size,
405 void (*destructor)(void *), void (*dealloc)(void *, size_t)) {
406 if ( NULL != array_address ) {
407 char *vec_base = static_cast <char *> (array_address);
408 char *heap_block = vec_base - padding_size;
409 const size_t element_count = padding_size ? __get_element_count ( p: vec_base ) : 0;
410 const size_t heap_block_size = element_size * element_count + padding_size;
411 st_heap_block3 heap ( dealloc, heap_block, heap_block_size );
412
413 if ( 0 != padding_size && NULL != destructor ) // call the destructors
414 __cxa_vec_dtor ( array_address: array_address, element_count: element_count, element_size: element_size, destructor: destructor );
415 }
416}
417
418
419} // extern "C"
420
421} // abi
422

source code of libcxxabi/src/cxa_vector.cpp