424 lines
9.4 KiB
C
424 lines
9.4 KiB
C
/*-
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* Copyright (c) 1991, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Edward Sze-Tyan Wang.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#ifndef lint
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static const char sccsid[] = "@(#)forward.c 8.1 (Berkeley) 6/6/93";
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#endif
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#include <sys/param.h>
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#include <sys/mount.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/time.h>
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#include <sys/mman.h>
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#include <sys/event.h>
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#include <err.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include "extern.h"
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static void rlines(FILE *, const char *fn, off_t, struct stat *);
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static int show(file_info_t *);
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static void set_events(file_info_t *files);
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/* defines for inner loop actions */
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#define USE_SLEEP 0
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#define USE_KQUEUE 1
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#define ADD_EVENTS 2
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static struct kevent *ev;
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static int action = USE_SLEEP;
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static int kq;
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static const file_info_t *last;
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/*
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* forward -- display the file, from an offset, forward.
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*
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* There are eight separate cases for this -- regular and non-regular
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* files, by bytes or lines and from the beginning or end of the file.
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*
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* FBYTES byte offset from the beginning of the file
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* REG seek
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* NOREG read, counting bytes
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*
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* FLINES line offset from the beginning of the file
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* REG read, counting lines
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* NOREG read, counting lines
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*
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* RBYTES byte offset from the end of the file
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* REG seek
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* NOREG cyclically read characters into a wrap-around buffer
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*
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* RLINES
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* REG mmap the file and step back until reach the correct offset.
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* NOREG cyclically read lines into a wrap-around array of buffers
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*/
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void
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forward(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
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{
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int ch;
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switch(style) {
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case FBYTES:
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if (off == 0)
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break;
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if (S_ISREG(sbp->st_mode)) {
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if (sbp->st_size < off)
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off = sbp->st_size;
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if (fseeko(fp, off, SEEK_SET) == -1) {
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ierr(fn);
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return;
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}
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} else while (off--)
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if ((ch = getc(fp)) == EOF) {
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if (ferror(fp)) {
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ierr(fn);
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return;
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}
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break;
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}
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break;
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case FLINES:
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if (off == 0)
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break;
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for (;;) {
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if ((ch = getc(fp)) == EOF) {
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if (ferror(fp)) {
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ierr(fn);
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return;
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}
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break;
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}
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if (ch == '\n' && !--off)
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break;
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}
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break;
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case RBYTES:
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if (S_ISREG(sbp->st_mode)) {
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if (sbp->st_size >= off &&
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fseeko(fp, -off, SEEK_END) == -1) {
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ierr(fn);
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return;
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}
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} else if (off == 0) {
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while (getc(fp) != EOF);
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if (ferror(fp)) {
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ierr(fn);
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return;
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}
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} else
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if (bytes(fp, fn, off))
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return;
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break;
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case RLINES:
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if (S_ISREG(sbp->st_mode))
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if (!off) {
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if (fseeko(fp, (off_t)0, SEEK_END) == -1) {
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ierr(fn);
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return;
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}
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} else
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rlines(fp, fn, off, sbp);
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else if (off == 0) {
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while (getc(fp) != EOF);
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if (ferror(fp)) {
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ierr(fn);
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return;
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}
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} else
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if (lines(fp, fn, off))
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return;
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break;
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default:
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break;
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}
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while ((ch = getc(fp)) != EOF)
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if (putchar(ch) == EOF)
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oerr();
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if (ferror(fp)) {
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ierr(fn);
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return;
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}
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(void)fflush(stdout);
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}
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/*
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* rlines -- display the last offset lines of the file.
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*/
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static void
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rlines(FILE *fp, const char *fn, off_t off, struct stat *sbp)
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{
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struct mapinfo map;
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off_t curoff, size;
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int i;
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if (!(size = sbp->st_size))
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return;
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map.start = NULL;
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map.fd = fileno(fp);
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map.mapoff = map.maxoff = size;
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/*
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* Last char is special, ignore whether newline or not. Note that
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* size == 0 is dealt with above, and size == 1 sets curoff to -1.
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*/
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curoff = size - 2;
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while (curoff >= 0) {
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if (curoff < map.mapoff && maparound(&map, curoff) != 0) {
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ierr(fn);
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return;
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}
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for (i = curoff - map.mapoff; i >= 0; i--)
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if (map.start[i] == '\n' && --off == 0)
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break;
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/* `i' is either the map offset of a '\n', or -1. */
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curoff = map.mapoff + i;
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if (i >= 0)
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break;
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}
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curoff++;
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if (mapprint(&map, curoff, size - curoff) != 0) {
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ierr(fn);
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exit(1);
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}
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/* Set the file pointer to reflect the length displayed. */
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if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) {
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ierr(fn);
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return;
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}
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if (map.start != NULL && munmap(map.start, map.maplen)) {
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ierr(fn);
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return;
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}
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}
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static int
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show(file_info_t *file)
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{
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int ch;
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while ((ch = getc(file->fp)) != EOF) {
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if (last != file && no_files > 1) {
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if (!qflag)
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(void)printf("\n==> %s <==\n", file->file_name);
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last = file;
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}
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if (putchar(ch) == EOF)
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oerr();
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}
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(void)fflush(stdout);
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if (ferror(file->fp)) {
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fclose(file->fp);
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file->fp = NULL;
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ierr(file->file_name);
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return 0;
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}
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clearerr(file->fp);
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return 1;
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}
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static void
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set_events(file_info_t *files)
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{
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int i, n = 0;
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file_info_t *file;
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struct timespec ts;
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struct statfs sf;
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ts.tv_sec = 0;
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ts.tv_nsec = 0;
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action = USE_KQUEUE;
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for (i = 0, file = files; i < no_files; i++, file++) {
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if (! file->fp)
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continue;
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if (fstatfs(fileno(file->fp), &sf) == 0 &&
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(sf.f_flags & MNT_LOCAL) == 0) {
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action = USE_SLEEP;
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return;
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}
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if (Fflag && fileno(file->fp) != STDIN_FILENO) {
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EV_SET(&ev[n], fileno(file->fp), EVFILT_VNODE,
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EV_ADD | EV_ENABLE | EV_CLEAR,
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NOTE_DELETE | NOTE_RENAME, 0, 0);
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n++;
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}
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EV_SET(&ev[n], fileno(file->fp), EVFILT_READ,
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EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0);
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n++;
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}
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if (kevent(kq, ev, n, NULL, 0, &ts) < 0) {
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action = USE_SLEEP;
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}
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}
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/*
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* follow -- display the file, from an offset, forward.
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*
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*/
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void
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follow(file_info_t *files, enum STYLE style, off_t off)
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{
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int active, ev_change, i, n = -1;
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struct stat sb2;
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file_info_t *file;
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struct timespec ts;
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/* Position each of the files */
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file = files;
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active = 0;
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n = 0;
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for (i = 0; i < no_files; i++, file++) {
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if (file->fp) {
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active = 1;
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n++;
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if (no_files > 1 && !qflag)
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(void)printf("\n==> %s <==\n", file->file_name);
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forward(file->fp, file->file_name, style, off, &file->st);
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if (Fflag && fileno(file->fp) != STDIN_FILENO)
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n++;
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}
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}
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if (!Fflag && !active)
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return;
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last = --file;
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kq = kqueue();
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if (kq < 0)
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err(1, "kqueue");
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ev = malloc(n * sizeof(struct kevent));
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if (! ev)
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err(1, "Couldn't allocate memory for kevents.");
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set_events(files);
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for (;;) {
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ev_change = 0;
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if (Fflag) {
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for (i = 0, file = files; i < no_files; i++, file++) {
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if (!file->fp) {
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file->fp = fopen(file->file_name, "r");
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if (file->fp != NULL &&
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fstat(fileno(file->fp), &file->st)
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== -1) {
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fclose(file->fp);
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file->fp = NULL;
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}
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if (file->fp != NULL)
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ev_change++;
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continue;
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}
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if (fileno(file->fp) == STDIN_FILENO)
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continue;
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if (stat(file->file_name, &sb2) == -1) {
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if (errno != ENOENT)
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ierr(file->file_name);
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show(file);
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if (file->fp != NULL) {
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fclose(file->fp);
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file->fp = NULL;
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}
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ev_change++;
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continue;
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}
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if (sb2.st_ino != file->st.st_ino ||
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sb2.st_dev != file->st.st_dev ||
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sb2.st_nlink == 0) {
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show(file);
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file->fp = freopen(file->file_name, "r",
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file->fp);
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if (file->fp != NULL)
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memcpy(&file->st, &sb2,
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sizeof(struct stat));
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else if (errno != ENOENT)
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ierr(file->file_name);
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ev_change++;
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}
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}
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}
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for (i = 0, file = files; i < no_files; i++, file++)
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if (file->fp && !show(file))
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ev_change++;
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if (ev_change)
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set_events(files);
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switch (action) {
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case USE_KQUEUE:
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ts.tv_sec = 1;
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ts.tv_nsec = 0;
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/*
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* In the -F case we set a timeout to ensure that
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* we re-stat the file at least once every second.
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*/
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n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL);
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if (n < 0)
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err(1, "kevent");
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if (n == 0) {
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/* timeout */
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break;
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} else if (ev->filter == EVFILT_READ && ev->data < 0) {
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/* file shrank, reposition to end */
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if (lseek(ev->ident, (off_t)0, SEEK_END) == -1) {
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ierr(file->file_name);
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continue;
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}
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}
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break;
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case USE_SLEEP:
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(void) usleep(250000);
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break;
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}
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}
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}
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