freebsd-dev/usr.bin/tail/misc.c
2001-12-12 00:01:16 +00:00

124 lines
3.5 KiB
C

/*-
* Copyright (c) 1991, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Edward Sze-Tyan Wang.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#ifndef lint
static const char sccsid[] = "@(#)misc.c 8.1 (Berkeley) 6/6/93";
#endif
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "extern.h"
void
ierr()
{
warn("%s", fname);
rval = 1;
}
void
oerr()
{
err(1, "stdout");
}
/*
* Print `len' bytes from the file associated with `mip', starting at
* absolute file offset `startoff'. May move map window.
*/
int
mapprint(mip, startoff, len)
struct mapinfo *mip;
off_t startoff, len;
{
int n;
while (len > 0) {
if (startoff < mip->mapoff || startoff >= mip->mapoff +
mip->maplen) {
if (maparound(mip, startoff) != 0)
return (1);
}
n = (mip->mapoff + mip->maplen) - startoff;
if (n > len)
n = len;
WR(mip->start + (startoff - mip->mapoff), n);
startoff += n;
len -= n;
}
return (0);
}
/*
* Move the map window so that it contains the byte at absolute file
* offset `offset'. The start of the map window will be TAILMAPLEN
* aligned.
*/
int
maparound(mip, offset)
struct mapinfo *mip;
off_t offset;
{
if (mip->start != NULL && munmap(mip->start, mip->maplen) != 0)
return (1);
mip->mapoff = offset & ~((off_t)TAILMAPLEN - 1);
mip->maplen = TAILMAPLEN;
if (mip->maplen > mip->maxoff - mip->mapoff)
mip->maplen = mip->maxoff - mip->mapoff;
if (mip->maplen <= 0)
abort();
if ((mip->start = mmap(NULL, mip->maplen, PROT_READ, MAP_SHARED,
mip->fd, mip->mapoff)) == MAP_FAILED)
return (1);
return (0);
}