这篇文章主要介绍“Linux下的进程虚拟内存结构是什么”，在日常操作中，相信很多人在Linux下的进程虚拟内存结构是什么问题上存在疑惑，小编查阅了各式资料，整理出简单好用的操作方法，希望对大家解答”Linux下的进程虚拟内存结构是什么”的疑惑有所帮助！接下来，请跟着小编一起来学习吧！
PostgreSQL使用进程架构,每个连接对应一个后台进程,为了更好的理解这种架构,有必要深入理解进程的相关知识
一、虚拟内存
进程虚拟内存的详细结构如下图所示:
C样例程序如下:
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
void f(void)//子函数
{
int a;
int b;
int c;
a = 98;
b = 1024;
c = a * b;
printf("[f] a = %d, b = %d, c = a * b = %d\n", a, b, c);
printf("[f] Adresses of a: %p, b = %p, c = %p\n", (void *)&a, (void *)&b, (void *)&c);
}
int main(int ac, char **av, char **env)
{
int a;//本地变量,位于栈中
void *p;//指针,在堆中分配内存
int i;
int size;
printf("Address of a: %p\n", (void *)&a);
p = malloc(98);//在堆中分配内存
if (p == NULL)
{
fprintf(stderr, "Can't malloc\n");
return (EXIT_FAILURE);
}
printf("Allocated space in the heap: %p\n", p);
printf("Address of function main: %p\n", (void *)main);//main函数所在的内存地址
printf("First bytes of the main function:\n\t");
for (i = 0; i < 15; i++)
{
printf("%02x ", ((unsigned char *)main)[i]);//首16个字节
}
printf("\n");
printf("Address of the array of arguments: %p\n", (void *)av);//输入参数数组地址
printf("Addresses of the arguments:\n\t");//
for (i = 0; i < ac; i++)
{
printf("[%s]:%p ", av[i], av[i]);//打印输入参数
}
printf("\n");
printf("Address of the array of environment variables: %p\n", (void *)env);//环境变量地址
printf("Address of the first environment variables:\n");//环境变量信息
for (i = 0; i < 3; i++)
{
printf("\t[%p]:\"%s\"\n", env[i], env[i]);
}
i = 0;
while (env[i] != NULL)//以NULL作为终结
{
i++;
}
i++;
size = i * sizeof(char *);
printf("Size of the array env: %d elements -> %d bytes (0x%x)\n", i, size, size);//计算环境变量数组大小
f();//调用函数
getchar();//接受输入,进程不退出
return (EXIT_SUCCESS);
}编译并执行
[root@localhost hacker]# gcc -Wall -Wextra -Werror main-7.c -o 7
[root@localhost hacker]# ./7 Hello Hacker Jack!
Address of a: 0x7fff5b327bb8 --> 位于栈中
Allocated space in the heap: 0x9b6010 --> 位于堆中
Address of function main: 0x400729 --> 可执行文件
First bytes of the main function:
55 48 89 e5 48 83 ec 40 89 7d dc 48 89 75 d0
Address of the array of arguments: 0x7fff5b327cb8 -->参数数组地址
Addresses of the arguments:
[./7]:0x7fff5b329808 [Hello]:0x7fff5b32980c [Hacker]:0x7fff5b329812 [Jack!]:0x7fff5b329819 --> 输入参数
Address of the array of environment variables: 0x7fff5b327ce0 --> 环境变量数组
Address of the first environment variables:
[0x7fff5b32981f]:"XDG_SESSION_ID=1"
[0x7fff5b329830]:"HOSTNAME=localhost.localdomain"
[0x7fff5b32984f]:"SELINUX_ROLE_REQUESTED="
Size of the array env: 27 elements -> 216 bytes (0xd8)
[f] a = 98, b = 1024, c = a * b = 100352
[f] Adresses of a: 0x7fff5b327b7c, b = 0x7fff5b327b78, c = 0x7fff5b327b74 --> 函数f中的变量地址通过udis86可反编译,得到汇编代码
[root@localhost install]# echo "55 48 89 e5 48 83 ec 10 48 8d 45 f0 48 89 c6" | udcli -64 -x -o 400729
0000000000400729 55 push rbp
000000000040072a 4889e5 mov rbp, rsp
000000000040072d 4883ec10 sub rsp, 0x10
0000000000400731 488d45f0 lea rax, [rbp-0x10]
0000000000400735 4889c6 mov rsi, rax
[root@localhost install]#查看该进程的内存映射信息
[root@localhost install]# ps aux | grep "./7" | grep -v grep
root 6471 0.0 0.0 4348 348 pts/0 S+ 15:24 0:00 ./7 Hello Hacker Jack!
[root@localhost install]# cat /proc/6471/maps
00400000-00401000 r-xp 00000000 fd:00 134287606 /data/source/hacker/7
00600000-00601000 r--p 00000000 fd:00 134287606 /data/source/hacker/7
00601000-00602000 rw-p 00001000 fd:00 134287606 /data/source/hacker/7
009b6000-009d7000 rw-p 00000000 00:00 0 [heap]
7f95b5d16000-7f95b5ed8000 r-xp 00000000 fd:00 151914 /usr/lib64/libc-2.17.so
7f95b5ed8000-7f95b60d8000 ---p 001c2000 fd:00 151914 /usr/lib64/libc-2.17.so
7f95b60d8000-7f95b60dc000 r--p 001c2000 fd:00 151914 /usr/lib64/libc-2.17.so
7f95b60dc000-7f95b60de000 rw-p 001c6000 fd:00 151914 /usr/lib64/libc-2.17.so
7f95b60de000-7f95b60e3000 rw-p 00000000 00:00 0
7f95b60e3000-7f95b6105000 r-xp 00000000 fd:00 151907 /usr/lib64/ld-2.17.so
7f95b62f8000-7f95b62fb000 rw-p 00000000 00:00 0
7f95b6301000-7f95b6304000 rw-p 00000000 00:00 0
7f95b6304000-7f95b6305000 r--p 00021000 fd:00 151907 /usr/lib64/ld-2.17.so
7f95b6305000-7f95b6306000 rw-p 00022000 fd:00 151907 /usr/lib64/ld-2.17.so
7f95b6306000-7f95b6307000 rw-p 00000000 00:00 0
7fff5b309000-7fff5b32a000 rw-p 00000000 00:00 0 [stack]
7fff5b3f1000-7fff5b3f3000 r-xp 00000000 00:00 0 [vdso]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
[root@localhost install]#到此，关于“Linux下的进程虚拟内存结构是什么”的学习就结束了，希望能够解决大家的疑惑。理论与实践的搭配能更好的帮助大家学习，快去试试吧！若想继续学习更多相关知识，请继续关注亿速云网站，小编会继续努力为大家带来更多实用的文章！
