c++ - 页面映射写入只允许读取

Question

如果我将页面映射为只写:

int* mem_location = (int*)mmap(nullptr, getpagesize(), 
    PROT_WRITE, MAP_ANON | MAP_PRIVATE, -1, 0);

cout << "Read @" << mem_location << ". This should segfault: " 
     << *mem_location << endl;

cout << "doesn't though??" << endl;

为什么它不会在读取时出现段错误？

Answer 1

参见 man page :

On some hardware architectures (e.g., i386), PROT_WRITE implies PROT_READ.

你不应该依赖于这种行为。