usr.bin/tail/misc.c

   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  * 3. 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  * @(#)misc.c   8.1 (Berkeley) 6/6/93
  33  * $FreeBSD: src/usr.bin/tail/misc.c,v 1.4.8.2 2001/04/18 09:32:08 dwmalone Exp $
  34  * $DragonFly: src/usr.bin/tail/misc.c,v 1.3 2003/10/04 20:36:51 hmp Exp $
  35  */
  36
  37 #include <sys/types.h>
  38 #include <sys/stat.h>
  39 #include <sys/mman.h>
  40 #include <errno.h>
  41 #include <unistd.h>
  42 #include <stdio.h>
  43 #include <stdlib.h>
  44 #include <string.h>
  45 #include <err.h>
  46 #include "extern.h"
  47
  48 void
  49 ierr(void)
  50 {
  51         warn("%s", fname);
  52         rval = 1;
  53 }
  54
  55 void
  56 oerr(void)
  57 {
  58         err(1, "stdout");
  59 }
  60
  61 /*
  62  * Print `len' bytes from the file associated with `mip', starting at
  63  * absolute file offset `startoff'. May move map window.
  64  */
  65 int
  66 mapprint(struct mapinfo *mip, off_t startoff, off_t len)
  67 {
  68         int n;
  69
  70         while (len > 0) {
  71                 if (startoff < mip->mapoff ||
  72                     startoff >= (intmax_t)(mip->mapoff + mip->maplen)) {
  73                         if (maparound(mip, startoff) != 0)
  74                                 return (1);
  75                 }
  76                 n = (mip->mapoff + mip->maplen) - startoff;
  77                 if (n > len)
  78                         n = len;
  79                 WR(mip->start + (startoff - mip->mapoff), n);
  80                 startoff += n;
  81                 len -= n;
  82         }
  83         return (0);
  84 }
  85
  86 /*
  87  * Move the map window so that it contains the byte at absolute file
  88  * offset `offset'. The start of the map window will be TAILMAPLEN
  89  * aligned.
  90  */
  91 int
  92 maparound(struct mapinfo *mip, off_t offset)
  93 {
  94
  95         if (mip->start != NULL && munmap(mip->start, mip->maplen) != 0)
  96                 return (1);
  97
  98         mip->mapoff = offset & ~((off_t)TAILMAPLEN - 1);
  99         mip->maplen = TAILMAPLEN;
 100         if (mip->maplen > (uintmax_t)(mip->maxoff - mip->mapoff))
 101                 mip->maplen = mip->maxoff - mip->mapoff;
 102         if (mip->maplen <= 0)
 103                 abort();
 104         if ((mip->start = mmap(NULL, mip->maplen, PROT_READ, MAP_SHARED,
 105              mip->fd, mip->mapoff)) == MAP_FAILED)
 106                 return (1);
 107
 108         return (0);
 109 }