Linux sys_brk()系统调用实现分析

对于do_brk()功能的说明：

this is really a simplified "do_mmap".  it only handles anonymous maps(只处理匿名映射). eventually we may be able to do some brk-specific accounting here.

应用层使用brk()系统调用的例子：

/* sbrk and brk example */
#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>

int main()
{
        void *curr_brk, *tmp_brk = NULL;

        printf("Welcome to sbrk example:%d\n", getpid());

        /* sbrk(0) gives current program break location */
        tmp_brk = curr_brk = sbrk(0);
        printf("Program Break Location1:%p\n", curr_brk);
        getchar();