我对动态内存管理很新，并使用Fsanitise标志来查找内存管理问题。我不能使用vector来存储数据 - 我需要使用原始数组，以及＆＃34; new＆＃34;和＆＃34;删除＆＃34;管理堆对象。
当我尝试运行EuclideanVectorTester编译程序时出现以下错误但不确定问题是什么，请有人开导我吗？
weill % make
g++ -std=c++14 -Wall -Werror -O2 -fsanitize=address -c EuclideanVectorTester.cpp
g++ -std=c++14 -Wall -Werror -O2 -fsanitize=address -c EuclideanVector.cpp
g++ -fsanitize=address EuclideanVectorTester.o EuclideanVector.o -o EuclideanVectorTester
weill % ./EuclideanVectorTester
1
=================================================================
==15341==ERROR: AddressSanitizer: heap-buffer-overflow on address 0xb59007e0 at pc 0x8048ca7 bp 0xbfb47388 sp 0xbfb4737c
WRITE of size 8 at 0xb59007e0 thread T0
#0 0x8048ca6 in main (/tmp_amd/kamen/export/kamen/3/z3386180/cs6771/evec/EuclideanVectorTester+0x8048ca6)
#1 0xb6ecae45 in __libc_start_main (/lib/i386-linux-gnu/i686/cmov/libc.so.6+0x16e45)
0xb59007e0 is located 0 bytes to the right of 16-byte region [0xb59007d0,0xb59007e0)
allocated by thread T0 here:
#0 0xb722a4c4 in operator new[](unsigned int) (/usr/lib/libasan.so.1+0x524c4)
#1 0x8048b9a in main (/tmp_amd/kamen/export/kamen/3/z3386180/cs6771/evec/EuclideanVectorTester+0x8048b9a)
#2 0xb6ecae45 in __libc_start_main (/lib/i386-linux-gnu/i686/cmov/libc.so.6+0x16e45)
#3 0x8048d8c (/tmp_amd/kamen/export/kamen/3/z3386180/cs6771/evec/EuclideanVectorTester+0x8048d8c)
SUMMARY: AddressSanitizer: heap-buffer-overflow ??:0 main
Shadow bytes around the buggy address:
0x36b200a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36b200b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36b200c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36b200d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36b200e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x36b200f0: fa fa fa fa fa fa fa fa fa fa 00 00[fa]fa 04 fa
0x36b20100: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36b20110: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36b20120: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36b20130: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x36b20140: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Heap right redzone: fb
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack partial redzone: f4
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Contiguous container OOB:fc
ASan internal: fe
==15341==ABORTING
weill %
EuclideanVector.h文件是这样的：
#ifndef _EuclideanVector_h
#define _EuclideanVector_h
#include <iostream>
#include <algorithm>
namespace even {
class EuclideanVector {
public:
/*
* A constructor that takes the number of dimensions (as an unsigned int) but no magnitudes,
* sets the magnitude in each dimension as 0.0. This is the default constructor, with the default value being 1.
*/
template <typename NUM>
EuclideanVector(const NUM dimensions = 1):
EuclideanVector(dimensions, 0.0) {}; // delegating constructor; default constructor that takes in dimensions if there is user input, otherwise dimensions = 1 if it is an empty constructor
// target constructor for delegating constructor
template <typename NUM1, typename NUM2> // any numeric types of user input for dimensions and magnitude will be static_cast to unsigned int and double respectively
EuclideanVector(const NUM1 dimensions, const NUM2 magnitude){
// static cast to unsigned int and assign dimensions_ to that
dimensions_ = new unsigned int (static_cast<unsigned int>(dimensions));
// assign pointer "magnitude_" to dynamically-allocated memory of new unnamed array<double> object of size "dimensions_"
magnitude_ = new double [*dimensions_];
// fill the array<double> object "magnitude_" a number of "dimensions_" times, with the <double> value of "magnitude_" for each dimension
std::fill_n(magnitude_, dimensions_, static_cast<double>(magnitude));
}
/*
* Destructor: ~EuclideanVector
* The destructor deallocates any memory acquired by the constructors.
*/
~EuclideanVector();
/*
* Member function: getMagnitude()
* Returns a double containing the number of dimensions in a particular array.
*/
const double& getMagnitude () const;
/*
* Member function: getNumDimensions()
* Returns an unsigned int containing the number of dimensions in a particular vector.
*/
unsigned int getNumDimensions() const;
private:
/* Everything from here to the end of the class is private, so
* not accessible or intended for use for the client */
unsigned int *dimensions_;
double *magnitude_;
//double normal_;
};
}
#endif
EuclideanVector.cpp文件是：
#include "EuclideanVector.h"
#include <algorithm>
#include <cmath> // for sqrt
#include <sstream>
#include <iterator>
namespace even {
unsigned int EuclideanVector::getNumDimensions () const
{
return *dimensions_;
}
const double& EuclideanVector::getMagnitude () const
{
return *magnitude_;
}
// destructor
EuclideanVector::~EuclideanVector() {
delete dimensions_;
delete [] magnitude_;
}
}
和EuclideanVectorTester.cpp文件是这样的：
#include <iostream>
#include <vector>
#include <list>
#include "EuclideanVector.h"
int main() {
std::cout << "1" << std::endl;
evec::EuclideanVector a(2);
std::cout << "2" << std::endl;
std::cout << "3" << std::end;
}
答案 0 :(得分：6)
我要说的是，你的教授说的有很多不准确之处（至少可以说）。
话虽如此，问题在于您已将dimensions声明为unsigned int*，但您仍在使用它，就好像它是unsigned int一样：< / p>
std::fill_n(magnitude_, dimensions_, static_cast<double>(magnitude));
立即解决这个问题：
std::fill_n(magnitude_, *dimensions_, static_cast<double>(magnitude));
然而，这引出了一个问题：为什么简单的unsigned int需要成为指针，然后使用new进行分配。没有理由这样做，因为使用new 比你现在所做的更有效。
如果您已将dimensions_声明为：
unsigned int dimensions_;
而不是它是一个指针，那么分配给dimensons_的代码就变成了这个：
// no call to new is done
dimensions_ = static_cast<unsigned int>(dimensions);
// no dereference of a pointer needs to be done on the two lines below
magnitude_ = new double[dimensions_];
std::fill_n(magnitude_, dimensions_, static_cast<double>(magnitude));
不会对分配器进行额外调用，因此代码会立即变得更有效。
此外，析构函数现在看起来像这样：
EuclideanVector::~EuclideanVector()
{
delete [] magnitude_;
}
但即使已经说明了这一点，给出的答案只会解决问题，如果您使用同一个main程序进行测试。如果您将main更改为：
even::EuclideanVector a(2);
even::EuclideanVector b = a;
现在您将遇到不正确的复制语义。同样，上述修复只需要使main功能正常工作。如上例所示，将main更改为非常简单的内容，您会遇到更多问题。