df_u.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#ifdef __GLIBC__
#include <sys/statfs.h>
#else
#include <sys/param.h>
#include <sys/mount.h>
#endif

static int ok = EXIT_SUCCESS;

static void printsize(long long n)
{
    char unit = 'K';
    long long t;

    n *= 10;

    if (n > 1024*1024*10) {
        n /= 1024;
        unit = 'M';
    }

    if (n > 1024*1024*10) {
        n /= 1024;
        unit = 'G';
    }

    t = (n + 512) / 1024;
    printf("%4lld.%1lld%ci", t/10, t%10, unit);
}

static void sdf(const struct statfs *st, const char *s, int always) {
	if(st->f_blocks == 0 && !always) return;
#if defined __GNU__ || defined __linux__
	printf("%-20s  ", s);
#else
	printf("%-20s  ", st->f_mntfromname);
#endif
	printsize((long long)st->f_blocks * (long long)st->f_bsize);
	printf("  ");
	printsize((long long)(st->f_blocks - (long long)st->f_bfree) * st->f_bsize);
	printf("  ");
	printsize((long long)st->f_bfree * (long long)st->f_bsize);
	printf("   %d\n", (int)st->f_bsize);
}

static void df(const char *s, int always) {
    struct statfs st;

    if (statfs(s, &st) < 0) {
        fprintf(stderr, "%s: %s\n", s, strerror(errno));
        ok = EXIT_FAILURE;
    } else {
		sdf(&st, s, always);
    }
}

int df_main(int argc, char *argv[]) {
    puts("Filesystem                Size     Used     Free   Blksize");
    if (argc == 1) {
#if defined __GNU__ || defined __linux__
        char s[2000];
        FILE *f = fopen("/proc/mounts", "r");

		if(!f) {
			perror("/proc/mounts");
			return 1;
		}

        while(fgets(s, 2000, f)) {
            char *c, *e = s;

            for (c = s; *c; c++) {
                if (*c == ' ') {
                    e = c + 1;
                    break;
                }
            }

            for (c = e; *c; c++) {
                if (*c == ' ') {
                    *c = '\0';
                    break;
                }
            }

            df(e, 0);
        }

        fclose(f);
#else
		int i;

		int len = getfsstat(NULL, 0, MNT_NOWAIT);
		if(len < 0) {
			perror("getstatfs");
			return 1;
		}
		struct statfs buffer[len];
		if(getfsstat(buffer, len * sizeof(struct statfs), MNT_NOWAIT) < 0) {
			perror("getstatfs");
			return 1;
		}
		for(i=0; i<len; i++) sdf(buffer + i, NULL, 0);
#endif
    } else {
        int i;

        for (i = 1; i < argc; i++) {
            df(argv[i], 1);
        }
    }

    exit(ok);
}