cmd/tail/misc.c

	misc.c revision 209e49b2ff611e7d61ff58e13756ae67f51be550
/*
 * 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.
 * 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/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(const char *fname)
{
    warn("%s", fname);
    rval = 1;
}

void
oerr(void)
{
    err(1, "stdout");
}

/*
 * Print `len' bytes from the file associated with `mip', starting at
 * absolute file offset `startoff'. May move map window.
 */
int
mapprint(struct mapinfo *mip, off_t startoff, off_t len)
{
    int n;

    while (len > 0) {
        if (startoff < mip->mapoff || startoff >= mip->mapoff +
            (off_t)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(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 ((off_t)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);
}