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22da50cfc8
trying to open files rather than giving up when it encounters an error. ENOENT errors are not reported. As a result, files that are moved away then recreated are not at risk of being 'lost' to tail. Files that are recreated and temporarily have unreadable permissions will be shown when they are fixed. This behaviour is consistent with the GNU version of tail but without the verbiage that goes with the GNU version. This change also fixes error messages accompanying -f and -F. They no longer report problems with (null)! MFC after: 3 weeks
426 lines
9.5 KiB
C
426 lines
9.5 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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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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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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struct kevent *ev;
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int action = USE_SLEEP;
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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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fclose(file->fp);
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file->fp = NULL;
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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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