mmap.c

#include <unistd.h>
#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <err.h>

#define BUFFER_SIZE 1000
#define ALLOC_SIZE (100*1024*1024)

static char command[BUFFER_SIZE];

int main(void)
{
	pid_t pid;

	pid = getpid();
	snprintf(command, BUFFER_SIZE, "cat /proc/%d/maps", pid);

	puts("*** memory map before memory allocation ***");
	fflush(stdout);
	system(command);

	void *new_memory;
	new_memory = mmap(NULL, ALLOC_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
	if (new_memory == (void *) -1)
		err(EXIT_FAILURE, "mmap() failed");

	puts("");
	printf("*** succeeded to allocate memory: address = %p; size = 0x%x ***\n",
		new_memory, ALLOC_SIZE);
	puts("");
	
	puts("*** memory map after memory allocation ***");
	fflush(stdout);
	system(command);

	if (munmap(new_memory, ALLOC_SIZE) == -1)
		err(EXIT_FAILURE, "munmap() failed");
	exit(EXIT_SUCCESS);
}