Component bdls_memoryutil [Package bdls]

Provide a set of portable utilities for memory manipulation. More...

Namespaces
namespace	bdls

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Detailed Description

Outline

• Purpose
• Classes
• Description
  • Usage

Purpose:

Provide a set of portable utilities for memory manipulation.

Classes:

bdls::MemoryUtil

struct which scopes memory system utilities.

Description:

This component, bdls::MemoryUtil, defines a platform-independent interface for memory manipulation, providing utilities for querying page size, allocating/deallocating page-aligned memory, and utility to change memory protection.

Usage:

First, allocate one page of memory.

  int pageSize = bdls::MemoryUtil::pageSize();
  char *data = (char*)bdls::MemoryUtil::allocate(pageSize);

Write into the allocated buffer.

  data[0] = '1';

Make the memory write protected

  bdls::MemoryUtil::protect(data, pageSize,
                            bdls::MemoryUtil::k_ACCESS_READ);

Verify that data still could be read.

  assert('1' == data[0]);

Once again, try writing into the buffer. This should crash our process.

  data[0] = '2';

Restore read/write access and free the allocated memory. Actually, this will never be executed, as the process has already crashed.

  bdls::MemoryUtil::protect(data, pageSize,
                            bdls::MemoryUtil::k_ACCESS_READ_WRITE);
  bdls::MemoryUtil::free(data);