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#include <unistd.h>
#include <string.h>
#include <stdio.h>
#define PAGE_SIZE 4096
int main(void)
{
void *start, *brk;
start = sbrk(0);
printf("heap start: %p\n", start);
// test extending
if (sbrk(PAGE_SIZE) == NULL) {
fprintf(stderr, "failed to extend break\n");
return 1;
}
brk = sbrk(0);
printf("new break: %p\n", brk);
// test reextending
if (sbrk(PAGE_SIZE) == NULL) {
fprintf(stderr, "failed to extend break\n");
return 1;
}
brk = sbrk(0);
printf("new new break: %p\n", brk);
// test shrinking
if (sbrk(-PAGE_SIZE) == NULL) {
fprintf(stderr, "failed to shrink break\n");
return 1;
}
brk = sbrk(0);
printf("new new new break: %p\n", brk);
// test write
memset(start, 1, PAGE_SIZE);
return 0;
}
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