【Linux】应用程序内存段布局

一、各段内存布局

内存布局图

1.BSS段（Block Started by Symbol）未初始化段

2.linux ELF base address is 0x8048000

应用程序虚拟地址起始地址均为0x8048000

3.堆向高内存地址生长

4.栈向低内存地址生长

P.S.

// 查看进程ID 图片

ps aux

cat /proc/3794/maps

代码段——只读r 可执行x

起始地址必为0x8048000

二、数据存放位置

• 分析数据存放位置
  
  对比即可
  
  

结论

1.代码段：代码，全局常量（const）、字符串常量

2.数据段(广义数据段，含BSS段)：全局变量（初始化以及未初始化的）、静态变量（全局的和局部的、初始化的以及未初始化的）

3.堆：动态分配的区域

4.栈：局部变量（初始化以及未初始化的，但不包含静态变量）、局部只读变量（const）

动手尝试即可

#include <stdio.h>
#include <stdlib.h>

int global_init_a = 1;	//全局，初始化 ：数据段
int global_uninit_a;	//全局，未初始化：数据段
static int static_global_init_a =1;//全局，静态,初始化 ：数据段
static int static_global_uninit_a;//数据段
const int const_global_a =1; //全局常量 ：代码段

int global_init_b = 1;
int global_uninit_b;	//全局，未初始化
static int static_global_init_b =1;//全局，静态,初始化 :数据段
static int static_global_uninit_b;
const int const_global_b =1;

int main()
{
	int local_init_a = 1; //Stack 栈
	int local_uninit_a;
	static int static_local_init_a =1;//局部静态：数据段
	static int static_local_uninit_a;
	const int const_local_a =1; //局部常量：栈

	int local_init_b = 1;
	int local_uninit_b;
	static int static_local_init_b =1;
	static int static_local_uninit_b;
	const int const_local_b =1;

	int* malloc_p_a;
	malloc_p_a = malloc(sizeof(int));//通过malloc分配得到的，局部 ：堆

//打印地址
	printf("&global_init_a = %p, global_init_a =%d\n",&global_init_a,global_init_a);
	printf("global_uninit_a =%p, global_uninit_a = %d\n",&global_uninit_a,global_uninit_a);
	printf("&static_global_init_a =%p,static_global_init_a = %d\n",&static_global_init_a,static_global_init_a);
	printf("static_global_uninit_a = %p,static_global_uninit_a = %d\n",&static_global_uninit_a,static_global_uninit_a);
	printf("const_global_a = %p,const_global_a =%d\n",&const_global_a,const_global_a );

	printf("&global_init_b = %p, global_init_b =%d\n",&global_init_b,global_init_b);
	printf("global_uninit_b =%p, global_uninit_b = %d\n",&global_uninit_b,global_uninit_b);
	printf("&static_global_init_b =%p,static_global_init_b = %d\n",&static_global_init_b,static_global_init_b);
	printf("static_global_uninit_b = %p,static_global_uninit_b = %d\n",&static_global_uninit_b,static_global_uninit_b);
	printf("const_global_b = %p,const_global_b =%d\n",&const_global_b,const_global_b);

	printf("&local_init_a = %p,local_init_a =%d\n",&local_init_a,local_init_a);
	printf("&local_uninit_a =%p,local_uninit_a\n",&local_uninit_a,local_uninit_a);
	printf("&static_local_init_a = %p,static_local_init_a=%d\n",&static_local_init_a,static_local_init_a);
	printf("&static_local_uninit_a= %p,static_local_uninit_a= %d\n",&static_local_uninit_a,static_local_uninit_a);
	printf("&const_local_a =%p,const_local_a=%d\n", &const_local_a,const_local_a);

	printf("&local_init_b = %p,local_init_b =%d\n",&local_init_b,local_init_b);
	printf("&local_uninit_b =%p,local_uninit_b\n",&local_uninit_b,local_uninit_b);
	printf("&static_local_init_b = %p,static_local_init_b=%d\n",&static_local_init_b,static_local_init_b);
	printf("&static_local_uninit_b= %p,static_local_uninit_b= %d\n",&static_local_uninit_b,static_local_uninit_b);
	printf("&const_local_b =%p,const_local_b=%d\n", &const_local_b,const_local_b);

	printf("malloc_p_a = %p,malloc_p_a",&malloc_p_a,malloc_p_a);
	while(1);

	return 0;

}

三、BSS段

• （Block Started by Symbol）未初始化段
• 利用readelf –S 程序名 分析BSS段
• elf 为可执行文件类型