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/usr.bin/tail/misc.c

https://bitbucket.org/freebsd/freebsd-head/
C | 115 lines | 61 code | 14 blank | 40 comment | 14 complexity | bc249ac6ab19d81539003fddc9e52561 MD5 | raw file
  1/*-
  2 * Copyright (c) 1991, 1993
  3 *	The Regents of the University of California.  All rights reserved.
  4 *
  5 * This code is derived from software contributed to Berkeley by
  6 * Edward Sze-Tyan Wang.
  7 *
  8 * Redistribution and use in source and binary forms, with or without
  9 * modification, are permitted provided that the following conditions
 10 * are met:
 11 * 1. Redistributions of source code must retain the above copyright
 12 *    notice, this list of conditions and the following disclaimer.
 13 * 2. Redistributions in binary form must reproduce the above copyright
 14 *    notice, this list of conditions and the following disclaimer in the
 15 *    documentation and/or other materials provided with the distribution.
 16 * 4. Neither the name of the University nor the names of its contributors
 17 *    may be used to endorse or promote products derived from this software
 18 *    without specific prior written permission.
 19 *
 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 30 * SUCH DAMAGE.
 31 */
 32
 33#include <sys/cdefs.h>
 34
 35__FBSDID("$FreeBSD$");
 36
 37#ifndef lint
 38static const char sccsid[] = "@(#)misc.c	8.1 (Berkeley) 6/6/93";
 39#endif
 40
 41#include <sys/types.h>
 42#include <sys/stat.h>
 43#include <sys/mman.h>
 44
 45#include <err.h>
 46#include <errno.h>
 47#include <stdio.h>
 48#include <stdlib.h>
 49#include <string.h>
 50#include <unistd.h>
 51
 52#include "extern.h"
 53
 54void
 55ierr(const char *fname)
 56{
 57	warn("%s", fname);
 58	rval = 1;
 59}
 60
 61void
 62oerr(void)
 63{
 64	err(1, "stdout");
 65}
 66
 67/*
 68 * Print `len' bytes from the file associated with `mip', starting at
 69 * absolute file offset `startoff'. May move map window.
 70 */
 71int
 72mapprint(struct mapinfo *mip, off_t startoff, off_t len)
 73{
 74	int n;
 75
 76	while (len > 0) {
 77		if (startoff < mip->mapoff || startoff >= mip->mapoff +
 78		    (off_t)mip->maplen) {
 79			if (maparound(mip, startoff) != 0)
 80				return (1);
 81		}
 82		n = (mip->mapoff + mip->maplen) - startoff;
 83		if (n > len)
 84			n = len;
 85		WR(mip->start + (startoff - mip->mapoff), n);
 86		startoff += n;
 87		len -= n;
 88	}
 89	return (0);
 90}
 91
 92/*
 93 * Move the map window so that it contains the byte at absolute file
 94 * offset `offset'. The start of the map window will be TAILMAPLEN
 95 * aligned.
 96 */
 97int
 98maparound(struct mapinfo *mip, off_t offset)
 99{
100
101	if (mip->start != NULL && munmap(mip->start, mip->maplen) != 0)
102		return (1);
103
104	mip->mapoff = offset & ~((off_t)TAILMAPLEN - 1);
105	mip->maplen = TAILMAPLEN;
106	if ((off_t)mip->maplen > mip->maxoff - mip->mapoff)
107		mip->maplen = mip->maxoff - mip->mapoff;
108	if (mip->maplen <= 0)
109		abort();
110	if ((mip->start = mmap(NULL, mip->maplen, PROT_READ, MAP_SHARED,
111	     mip->fd, mip->mapoff)) == MAP_FAILED)
112		return (1);
113
114	return (0);
115}