FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/tests/zfs-tests/cmd/getversion.c

     /*
      * This file and its contents are supplied under the terms of the
      * Common Development and Distribution License ("CDDL"), version 1.0.
      * You may only use this file in accordance with the terms of version
      * 1.0 of the CDDL.
      *
      * A full copy of the text of the CDDL should have accompanied this
      * source.  A copy of the CDDL is also available via the Internet at
      * http://www.illumos.org/license/CDDL.
     */
    
    /*
     * Copyright 2021 iXsystems, Inc.
     */
    
    /*
     * FreeBSD and macOS expose file generation number through stat(2) and stat(1).
     * Linux exposes it instead through an ioctl.
     */
    
    #include <sys/ioctl.h>
    #include <sys/fcntl.h>
    #include <linux/fs.h>
    #include <err.h>
    #include <stdio.h>
    #include <stdlib.h>
    #include <unistd.h>
    
    int
    main(int argc, const char * const argv[])
    {
            if (argc != 2)
                    errx(EXIT_FAILURE, "usage: %s filename", argv[0]);
    
            int fd = open(argv[1], O_RDONLY);
            if (fd == -1)
                    err(EXIT_FAILURE, "failed to open %s", argv[1]);
    
            int gen = 0;
            if (ioctl(fd, FS_IOC_GETVERSION, &gen) == -1)
                    err(EXIT_FAILURE, "FS_IOC_GETVERSION failed");
    
            (void) close(fd);
    
            (void) printf("%d\n", gen);
    
            return (EXIT_SUCCESS);
    }

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