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. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *      This product includes software developed by the University of
  19  *      California, Berkeley and its contributors.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * @(#)misc.c   8.1 (Berkeley) 6/6/93
  37  * $FreeBSD: src/usr.bin/tail/misc.c,v 1.4.8.2 2001/04/18 09:32:08 dwmalone Exp $
  38  * $DragonFly: src/usr.bin/tail/misc.c,v 1.3 2003/10/04 20:36:51 hmp Exp $
  39  */
  40
  41 #include <sys/types.h>
  42 #include <sys/stat.h>
  43 #include <sys/mman.h>
  44 #include <errno.h>
  45 #include <unistd.h>
  46 #include <stdio.h>
  47 #include <stdlib.h>
  48 #include <string.h>
  49 #include <err.h>
  50 #include "extern.h"
  51
  52 void
  53 ierr(void)
  54 {
  55         warn("%s", fname);
  56         rval = 1;
  57 }
  58
  59 void
  60 oerr(void)
  61 {
  62         err(1, "stdout");
  63 }
  64
  65 /*
  66  * Print `len' bytes from the file associated with `mip', starting at
  67  * absolute file offset `startoff'. May move map window.
  68  */
  69 int
  70 mapprint(struct mapinfo *mip, off_t startoff, off_t len)
  71 {
  72         int n;
  73
  74         while (len > 0) {
  75                 if (startoff < mip->mapoff ||
  76                     startoff >= (intmax_t)(mip->mapoff + mip->maplen)) {
  77                         if (maparound(mip, startoff) != 0)
  78                                 return (1);
  79                 }
  80                 n = (mip->mapoff + mip->maplen) - startoff;
  81                 if (n > len)
  82                         n = len;
  83                 WR(mip->start + (startoff - mip->mapoff), n);
  84                 startoff += n;
  85                 len -= n;
  86         }
  87         return (0);
  88 }
  89
  90 /*
  91  * Move the map window so that it contains the byte at absolute file
  92  * offset `offset'. The start of the map window will be TAILMAPLEN
  93  * aligned.
  94  */
  95 int
  96 maparound(struct mapinfo *mip, off_t offset)
  97 {
  98
  99         if (mip->start != NULL && munmap(mip->start, mip->maplen) != 0)
 100                 return (1);
 101
 102         mip->mapoff = offset & ~((off_t)TAILMAPLEN - 1);
 103         mip->maplen = TAILMAPLEN;
 104         if (mip->maplen > (uintmax_t)(mip->maxoff - mip->mapoff))
 105                 mip->maplen = mip->maxoff - mip->mapoff;
 106         if (mip->maplen <= 0)
 107                 abort();
 108         if ((mip->start = mmap(NULL, mip->maplen, PROT_READ, MAP_SHARED,
 109              mip->fd, mip->mapoff)) == MAP_FAILED)
 110                 return (1);
 111
 112         return (0);
 113 }