//测试程序
#include "apue.h"
int glob = 1;
int main(void)
{
int var = 1;
int pid;
printf("before fork\n");
if((pid = vfork()) < 0)
{
perror("fork error");
exit(-1);
}
else if(pid == 0)
{
glob++;
var++;
printf("pid = %d, glob = %d, var = %d\n", getpid(), glob, var);
//printf("glob_address: %p\n", &glob);
//printf("var_address: %p\n", &var);
_exit(0);
}
printf("pid = %d, glob = %d, var = %d\n", getpid(), glob, var);
//printf("glob_address: %p\n", &glob);
//printf("var_address: %p\n", &var);
return 0;
}
1 此时没有让程序输入var和glob变量的地址,运行结果为
before fork
pid = 15865, glob = 2, var = 2
pid = 15864, glob = 2, var = 1
2 取消掉注释后,运行结果为
before fork
pid = 25515, glob = 2, var = 2
glob_address: 0x804a050
var_address: 0xbfa4d4cc
pid = 25514, glob = 2, var = 2
glob_address: 0x804a050
var_address: 0xbfa4d4cc
问题:(程序在codeblocks10.05中运行的,ubuntu12.04系统)
vfork创建一个进程后,在子进程调用exec或exit之前,它在父进程中执行,运行结果2也说明了这一点,var和glob的都被子进程给加1了,但是运行结果1的父进程var变并没有加1,貌似子进程没有共享父进程的堆栈空间一样,这是为什么?求帮助解答........