device_info.c

#include <fcntl.h>
#include <linux/fs.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>

int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage: %s device\n", argv[0]);
        return 0;
    }

    const char *device = argv[1];
    int fd = open(device, O_RDONLY);
    if (fd == -1) {
        perror("open(2)");
        exit(EXIT_FAILURE);
    }
    unsigned long long block_size = 0;
    if (ioctl(fd, BLKSSZGET, &block_size) == -1) {
        perror("ioctl(2)");
        exit(EXIT_FAILURE);
    }
    unsigned long long n_of_blocks = 0;
    if (ioctl(fd, BLKGETSIZE, &n_of_blocks) == -1) {
        perror("ioctl(2)");
        exit(EXIT_FAILURE);
    }
    close(fd);

    printf("device name: %s\n",         device);
    printf("block size:  %lld bytes\n", block_size);
    printf("# of blocks: %lld\n",       n_of_blocks);
    printf("volume:      %lld GiB\n",   block_size * n_of_blocks / (1 << 30));

    return 0;
}