cmd/file_trunc/file_trunc.c

d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy/*
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * CDDL HEADER START
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy *
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * The contents of this file are subject to the terms of the
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * Common Development and Distribution License (the "License").
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * You may not use this file except in compliance with the License.
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy *
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * or http://www.opensolaris.org/os/licensing.
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * See the License for the specific language governing permissions
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * and limitations under the License.
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy *
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * When distributing Covered Code, include this CDDL HEADER in each
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * If applicable, add the following below this CDDL HEADER, with the
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * fields enclosed by brackets "[]" replaced with your own identifying
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * information: Portions Copyright [yyyy] [name of copyright owner]
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy *
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * CDDL HEADER END
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy */
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy/*
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * Copyright 2007 Sun Microsystems, Inc.  All rights reserved.
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy * Use is subject to license terms.
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy */
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy/*
52244c0958bdf281ca42932b449f644b4decfdc2John Wren Kennedy * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy */
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <stdio.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <stdlib.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <unistd.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <limits.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <errno.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <fcntl.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <sys/types.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <sys/fcntl.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <sys/stat.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <sys/statvfs.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <sys/errno.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <sys/time.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <sys/ioctl.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <sys/wait.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <sys/param.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#include <string.h>
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#define FSIZE   256*1024*1024
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy#define BSIZE   512
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy/* Initialize Globals */
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic long fsize = FSIZE;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic size_t   bsize = BSIZE;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic int  count = 0;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic int  rflag = 0;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic int  seed = 0;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic int  vflag = 0;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic int  errflag = 0;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic off_t    offset = 0;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic char *filename = NULL;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic void usage(char *execname);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic void parse_options(int argc, char *argv[]);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic void do_write(int fd);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic void do_trunc(int fd);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic void
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedyusage(char *execname)
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy{
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    (void) fprintf(stderr,
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        "usage: %s [-b blocksize] [-c count] [-f filesize]"
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        " [-o offset] [-s seed] [-r] [-v] filename\n", execname);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    (void) exit(1);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy}
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedyint
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedymain(int argc, char *argv[])
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy{
52244c0958bdf281ca42932b449f644b4decfdc2John Wren Kennedy    int i;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    int fd = -1;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    parse_options(argc, argv);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    fd = open(filename, O_RDWR|O_CREAT|O_TRUNC, 0666);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    if (fd < 0) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        perror("open");
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        exit(3);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
52244c0958bdf281ca42932b449f644b4decfdc2John Wren Kennedy    for (i = 0; count == 0 || i < count; i++) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        (void) do_write(fd);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        (void) do_trunc(fd);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    (void) close(fd);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    return (0);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy}
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic void
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedyparse_options(int argc, char *argv[])
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy{
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    int c;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    extern char *optarg;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    extern int optind, optopt;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    count = fsize / bsize;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    seed = time(NULL);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    while ((c = getopt(argc, argv, "b:c:f:o:rs:v")) != -1) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        switch (c) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            case 'b':
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                bsize = atoi(optarg);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                break;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            case 'c':
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                count = atoi(optarg);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                break;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            case 'f':
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                fsize = atoi(optarg);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                break;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            case 'o':
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                offset = atoi(optarg);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                break;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            case 'r':
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                rflag++;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                break;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            case 's':
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                seed = atoi(optarg);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                break;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            case 'v':
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                vflag++;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                break;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            case ':':
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                (void) fprintf(stderr,
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                    "Option -%c requires an operand\n", optopt);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                errflag++;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                break;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            case '?':
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                (void) fprintf(stderr,
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                    "Unrecognized option: -%c\n", optopt);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                errflag++;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                break;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        if (errflag) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            (void) usage(argv[0]);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    if (argc <= optind) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        (void) fprintf(stderr,
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            "No filename specified\n");
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        usage(argv[0]);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    filename = argv[optind];
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    if (vflag) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        (void) fprintf(stderr, "Seed = %d\n", seed);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    srandom(seed);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy}
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic void
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedydo_write(int fd)
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy{
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    off_t   roffset = 0;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    char    *buf = NULL;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    char    *rbuf = NULL;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    buf = (char *)calloc(1, bsize);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    rbuf = (char *)calloc(1, bsize);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    if (buf == NULL || rbuf == NULL) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        perror("malloc");
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        exit(4);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    roffset = random() % fsize;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    if (lseek64(fd, (offset + roffset), SEEK_SET) < 0) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        perror("lseek");
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        exit(5);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
52244c0958bdf281ca42932b449f644b4decfdc2John Wren Kennedy    (void) strcpy(buf, "ZFS Test Suite Truncation Test");
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    if (write(fd, buf, bsize) < bsize) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        perror("write");
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        exit(6);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    if (rflag) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        if (lseek64(fd, (offset + roffset), SEEK_SET) < 0) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            perror("lseek");
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            exit(7);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        if (read(fd, rbuf, bsize) < bsize) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            perror("read");
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            exit(8);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        if (memcmp(buf, rbuf, bsize) != 0) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            perror("memcmp");
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            exit(9);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    if (vflag) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        (void) fprintf(stderr,
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            "Wrote to offset %lld\n", (offset + roffset));
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        if (rflag) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            (void) fprintf(stderr,
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy                "Read back from offset %lld\n", (offset + roffset));
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    (void) free(buf);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    (void) free(rbuf);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy}
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedystatic void
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedydo_trunc(int fd)
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy{
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    off_t   roffset = 0;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    roffset = random() % fsize;
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    if (ftruncate64(fd, (offset + roffset))  < 0) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        perror("truncate");
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        exit(7);
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    if (vflag) {
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy        (void) fprintf(stderr,
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            "Truncated at offset %lld\n",
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy            (offset + roffset));
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy    }
d583b39bfb4e2571d3e41097c5c357ffe353ad45John Wren Kennedy}