Get The Remaining Size of A Typed Memory

Sometimes you may want to get the reamining size of a typed memory region, but you can't find the right tool to view the remaining size, you can use the following code to get it.

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <fcntl.h>

int main(void) {
	int fd;
	int ret;
	struct posix_typed_mem_info info;

	fd = posix_typed_mem_open( "/memory/below4G/ram", O_RDWR,
				POSIX_TYPED_MEM_ALLOCATE_CONTIG);
	if (fd == -1) {
		printf("Can not open below4G ram\n");
		return EXIT_FAILURE;
	}

	ret = posix_typed_mem_get_info(
		fd,
		&info);
	if (!ret) {
		printf("below4G ram: %.2fMB\n", (float)info.posix_tmi_length/1024/1024);
	}

	close(fd);

	return EXIT_SUCCESS;
}