裸机无全球运营商新品 [英] Bare metal without global operator new

问题描述

考虑安全软件，一般不允许动态分配，不允许异常。仅当类明确定义运算符新和 delete 时，才允许动态分配。使用运算符 new 为其他类应该导致编译失败。

在描述的情况下，最简单的导致编译失败的方法是删除全局新运算符：

  void * operator new（std :: size_t）= delete; 
  

一方面，这会导致标准库的副作用。例如，包含< array> 将< new_allocator> 通过< stdexcept> ; 。 < new_allocator> 使用 :: new 运算符，即使您不想使用异常和内存分配。根据Scoot Meyers < array> 应该是裸机友好的。

另一方面，编译器内置操作符的原因错误

  src / main.cpp：91：31：错误：删除'void * operator new（std :: size_t）'的定义
 void * operator new（std :: size_t）= delete; ^ 
< built-in> ;:注意：以前声明的'void * operator new（std :: size_t）'
  

是否有解决方案禁止 :: new 并使用< array> ？

是否有任何解决方案可以全部禁止全新 c p>

解决方案

如果你使用GCC和GNU LD，那么我想你可以添加 - wrap = malloc 到您的链接器标志。由于全局 :: new 在内部使用 malloc（），所有调用 malloc（）在您的应用程序将被替换为 __ wrap_malloc（）。如果此函数未定义，则链接将失败。

另一个可能更简单的选项是添加 ASSERT（DEFINED（malloc）== 0，动态分配使用！）; 到您的链接描述文件。这将断言 malloc（）未定义。

这两个选项都不保护您不重新定义全局 :: new 使用其他形式的全局分配。您可以在链接描述文件中对全局符号 :: new 执行相同的操作，但其名称为mangled（在这里 _Znwj ），所以这会有点奇怪...

Consider safety software, where dynamic allocation in general is disallowed and exceptions are disallowed. Dynamic allocation is allowed only when class explicity defines operator new and delete. Using operator new for others class should cause compilation failure.

The simplest way to cause compilation failure in described situation is to remove global new operator:

void* operator new(std::size_t) = delete;

On the one hand this cause side effects with standard library. For example including <array> propagates inclusion to <new_allocator> by <stdexcept>. <new_allocator> uses ::new operator and this cause build fail even when You don't want to use exception and memory allocation. According to Scoot Meyers <array> should be bare metal friendly.

On the other hand this cause error with compiler built-in operator

src/main.cpp:91:31: error: deleted definition of 'void* operator new(std::size_t)'
 void* operator new(std::size_t) = delete;                               ^
<built-in>: note: previous declaration of 'void* operator new(std::size_t)'

Is there any solution to ban ::new and use <array>?

Is there any solution to ban ::new globally at all?

解决方案

If you use GCC and GNU LD, then I think you can just add --wrap=malloc to your linker flags. As global ::new uses malloc() internally, all calls to malloc() in your application will be replaced with __wrap_malloc(). If this function is undefined, then the linking will fail.

Another, possibly simpler option, is to add ASSERT(DEFINED(malloc) == 0, "Dynamic allocation used!"); to your linker script. This will assert that malloc() is not defined.

Neither of these options protect you from redefining global ::new to use some other form of global allocation. You could do the same for global symbol ::new in the linker script, but its name is mangled (in here _Znwj), so this will be a little strange...

这篇关于裸机无全球运营商新品的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！