busybox/miscutils/mountpoint.c

/* vi: set sw=4 ts=4: */
/*
 * mountpoint implementation for busybox
 *
 * Copyright (C) 2005 Bernhard Fischer
 *
 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
 *
 * Based on sysvinit's mountpoint
 */

#include <sys/stat.h>
#include <errno.h> /* errno */
#include <string.h> /* strerror */
#include <getopt.h> /* optind */
#include "busybox.h"

int mountpoint_main(int argc, char **argv)
{
	int opt = bb_getopt_ulflags(argc, argv, "qdx");
#define OPT_q (1)
#define OPT_d (2)
#define OPT_x (4)

	if (optind != argc - 1)
		bb_show_usage();
	{
		char *arg = argv[optind];
		struct stat st;

		if ( (opt & OPT_x && stat(arg, &st) == 0) || (lstat(arg, &st) == 0) ) {
			if (opt & OPT_x) {
				if (S_ISBLK(st.st_mode))
				{
					bb_printf("%u:%u\n", major(st.st_rdev),
								minor(st.st_rdev));
					return EXIT_SUCCESS;
				} else {
					if (opt & OPT_q)
						putchar('\n');
					else
						bb_error_msg("%s: not a block device", arg);
				}
				return EXIT_FAILURE;
			} else
			if (S_ISDIR(st.st_mode)) {
				dev_t st_dev = st.st_dev;
				ino_t st_ino = st.st_ino;
				char *p = bb_xasprintf("%s/..", arg);

				if (stat(p, &st) == 0) {
					short ret = (st_dev != st.st_dev) ||
						(st_dev == st.st_dev && st_ino == st.st_ino);
					if (opt & OPT_d)
						bb_printf("%u:%u\n", major(st_dev), minor(st_dev));
					else if (!(opt & OPT_q))
						bb_printf("%s is %sa mountpoint\n", arg, ret?"":"not ");
					return !ret;
				}
			} else {
				if (!(opt & OPT_q))
					bb_error_msg("%s: not a directory", arg);
				return EXIT_FAILURE;
			}
		}
		if (!(opt & OPT_q))
			bb_perror_msg("%s", arg);
		return EXIT_FAILURE;
	}
}