[C++] 纯文本查看 复制代码
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/resource.h>
int bssvar; //声明一个味定义的变量，它会放在 bss segment 中
int main(void)
{
char *pmem;
long heap_gap_bss;
printf ("end of bss section:%p\n", (long)&bssvar + 4);
pmem = (char *)malloc(32); //从堆中分配一块内存区，一般从堆的开始处获取
if (pmem == NULL) {
perror("malloc");
exit (EXIT_FAILURE);
}
printf ("pmem:%p\n", pmem);
//计算堆的开始地址和 bss segment 结束处得空隙大小，注意每次加载程序时这个空隙都是变化的，但是在同一次加载中它不会改变
heap_gap_bss = (long)pmem - (long)&bssvar - 4;
printf ("1-gap between heap and bss:%lu\n", heap_gap_bss);
free (pmem); //释放内存，归还给堆
sbrk(32); //调整 program break 位置(假设现在不知道这个位置在堆头还是堆尾)
pmem = (char *)malloc(32); //再一次获取内存区
if (pmem == NULL) {
perror("malloc");
exit (EXIT_FAILURE);
}
printf ("pmem:%p\n", pmem); //检查和第一次获取的内存区的起始地址是否一样
heap_gap_bss = (long)pmem - (long)&bssvar - 4; //计算调整 program break 后的空隙
printf ("2-gap between heap and bss:%lu\n", heap_gap_bss);
free(pmem); //释放
return 0;
}
[C++] 纯文本查看 复制代码
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/resource.h>
int main(void)
{
void *tret;
char *pmem;
pmem = (char *)malloc(32);
if (pmem == NULL) {
perror("malloc");
exit (EXIT_FAILURE);
}
printf ("pmem:%p\n", pmem);
tret = sbrk(0);
if (tret != (void *)-1)
printf ("heap size on each load: %lu\n", (long)tret - (long)pmem);
return 0;
}
[C++] 纯文本查看 复制代码
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/resource.h>
int main(void)
{
void *tret;
char *pmem;
int i;
long sbrkret;
pmem = (char *)malloc(32);
if (pmem == NULL) {
perror("malloc");
exit (EXIT_FAILURE);
}
printf ("pmem:%p\n", pmem);
for (i = 0; i < 65; i++) {
sbrk(1);
printf ("%d\n", sbrk(0) - (long)pmem - 0x20ff8); //0x20ff8 就是堆和 bss段 之间的空隙常数；改变后要用 sbrk(0) 再次获取更新后的program break位置
}
free(pmem);
return 0;
}