/*-
* SPDX-License-Identifier: BSD-3-Clause
*
* 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.
* 3. 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/cdefs.h>
__FBSDID("$FreeBSD$");
#ifndef lint
static const char sccsid[] = "@(#)forward.c 8.1 (Berkeley) 6/6/93";
#endif
#include <sys/param.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <sys/event.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "extern.h"
static void rlines(FILE *, const char *fn, off_t, struct stat *);
static int show(file_info_t *);
static void set_events(file_info_t *files);
/* defines for inner loop actions */
#define USE_SLEEP 0
#define USE_KQUEUE 1
#define ADD_EVENTS 2
static struct kevent *ev;
static int action = USE_SLEEP;
static int kq;
static const file_info_t *last;
/*
* forward -- display the file, from an offset, forward.
*
* There are eight separate cases for this -- regular and non-regular
* files, by bytes or lines and from the beginning or end of the file.
*
* FBYTES byte offset from the beginning of the file
* REG seek
* NOREG read, counting bytes
*
* FLINES line offset from the beginning of the file
* REG read, counting lines
* NOREG read, counting lines
*
* RBYTES byte offset from the end of the file
* REG seek
* NOREG cyclically read characters into a wrap-around buffer
*
* RLINES
* REG mmap the file and step back until reach the correct offset.
* NOREG cyclically read lines into a wrap-around array of buffers
*/
void
forward(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
{
int ch;
switch(style) {
case FBYTES:
if (off == 0)
break;
if (S_ISREG(sbp->st_mode)) {
if (sbp->st_size < off)
off = sbp->st_size;
if (fseeko(fp, off, SEEK_SET) == -1) {
ierr(fn);
return;
}
} else while (off--)
if ((ch = getc(fp)) == EOF) {
if (ferror(fp)) {
ierr(fn);
return;
}
break;
}
break;
case FLINES:
if (off == 0)
break;
for (;;) {
if ((ch = getc(fp)) == EOF) {
if (ferror(fp)) {
ierr(fn);
return;
}
break;
}
if (ch == '\n' && !--off)
break;
}
break;
case RBYTES:
if (S_ISREG(sbp->st_mode)) {
if (sbp->st_size >= off &&
fseeko(fp, -off, SEEK_END) == -1) {
ierr(fn);
return;
}
} else if (off == 0) {
while (getc(fp) != EOF);
if (ferror(fp)) {
ierr(fn);
return;
}
} else
if (bytes(fp, fn, off))
return;
break;
case RLINES:
if (S_ISREG(sbp->st_mode))
if (!off) {
if (fseeko(fp, (off_t)0, SEEK_END) == -1) {
ierr(fn);
return;
}
} else
rlines(fp, fn, off, sbp);
else if (off == 0) {
while (getc(fp) != EOF);
if (ferror(fp)) {
ierr(fn);
return;
}
} else
if (lines(fp, fn, off))
return;
break;
default:
break;
}
while ((ch = getc(fp)) != EOF)
if (putchar(ch) == EOF)
oerr();
if (ferror(fp)) {
ierr(fn);
return;
}
(void)fflush(stdout);
}
/*
* rlines -- display the last offset lines of the file.
*/
static void
rlines(FILE *fp, const char *fn, off_t off, struct stat *sbp)
{
struct mapinfo map;
off_t curoff, size;
int i;
if (!(size = sbp->st_size))
return;
map.start = NULL;
map.fd = fileno(fp);
map.mapoff = map.maxoff = size;
/*
* Last char is special, ignore whether newline or not. Note that
* size == 0 is dealt with above, and size == 1 sets curoff to -1.
*/
curoff = size - 2;
while (curoff >= 0) {
if (curoff < map.mapoff && maparound(&map, curoff) != 0) {
ierr(fn);
return;
}
for (i = curoff - map.mapoff; i >= 0; i--)
if (map.start[i] == '\n' && --off == 0)
break;
/* `i' is either the map offset of a '\n', or -1. */
curoff = map.mapoff + i;
if (i >= 0)
break;
}
curoff++;
if (mapprint(&map, curoff, size - curoff) != 0) {
ierr(fn);
exit(1);
}
/* Set the file pointer to reflect the length displayed. */
if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) {
ierr(fn);
return;
}
if (map.start != NULL && munmap(map.start, map.maplen)) {
ierr(fn);
return;
}
}
static int
show(file_info_t *file)
{
int ch;
while ((ch = getc(file->fp)) != EOF) {
if (last != file && no_files > 1) {
if (!qflag)
printfn(file->file_name, 1);
last = file;
}
if (putchar(ch) == EOF)
oerr();
}
(void)fflush(stdout);
if (ferror(file->fp)) {
fclose(file->fp);
file->fp = NULL;
ierr(file->file_name);
return 0;
}
clearerr(file->fp);
return 1;
}
static void
set_events(file_info_t *files)
{
int i, n = 0;
file_info_t *file;
struct timespec ts;
struct statfs sf;
ts.tv_sec = 0;
ts.tv_nsec = 0;
action = USE_KQUEUE;
for (i = 0, file = files; i < no_files; i++, file++) {
if (! file->fp)
continue;
if (fstatfs(fileno(file->fp), &sf) == 0 &&
(sf.f_flags & MNT_LOCAL) == 0) {
action = USE_SLEEP;
return;
}
if (Fflag && fileno(file->fp) != STDIN_FILENO) {
EV_SET(&ev[n], fileno(file->fp), EVFILT_VNODE,
EV_ADD | EV_ENABLE | EV_CLEAR,
NOTE_DELETE | NOTE_RENAME, 0, 0);
n++;
}
EV_SET(&ev[n], fileno(file->fp), EVFILT_READ,
EV_ADD | EV_ENABLE | EV_CLEAR, 0, 0, 0);
n++;
}
if (kevent(kq, ev, n, NULL, 0, &ts) < 0) {
action = USE_SLEEP;
}
}
/*
* follow -- display the file, from an offset, forward.
*
*/
void
follow(file_info_t *files, enum STYLE style, off_t off)
{
int active, ev_change, i, n = -1;
struct stat sb2;
file_info_t *file;
struct timespec ts;
/* Position each of the files */
file = files;
active = 0;
n = 0;
for (i = 0; i < no_files; i++, file++) {
if (file->fp) {
active = 1;
n++;
if (no_files > 1 && !qflag)
printfn(file->file_name, 1);
forward(file->fp, file->file_name, style, off, &file->st);
if (Fflag && fileno(file->fp) != STDIN_FILENO)
n++;
}
}
if (!Fflag && !active)
return;
last = --file;
kq = kqueue();
if (kq < 0)
err(1, "kqueue");
ev = malloc(n * sizeof(struct kevent));
if (! ev)
err(1, "Couldn't allocate memory for kevents.");
set_events(files);
for (;;) {
ev_change = 0;
if (Fflag) {
for (i = 0, file = files; i < no_files; i++, file++) {
if (!file->fp) {
file->fp = fopen(file->file_name, "r");
if (file->fp != NULL &&
fstat(fileno(file->fp), &file->st)
== -1) {
fclose(file->fp);
file->fp = NULL;
}
if (file->fp != NULL)
ev_change++;
continue;
}
if (fileno(file->fp) == STDIN_FILENO)
continue;
if (stat(file->file_name, &sb2) == -1) {
if (errno != ENOENT)
ierr(file->file_name);
show(file);
if (file->fp != NULL) {
fclose(file->fp);
file->fp = NULL;
}
ev_change++;
continue;
}
if (sb2.st_ino != file->st.st_ino ||
sb2.st_dev != file->st.st_dev ||
sb2.st_nlink == 0) {
show(file);
file->fp = freopen(file->file_name, "r",
file->fp);
if (file->fp != NULL)
memcpy(&file->st, &sb2,
sizeof(struct stat));
else if (errno != ENOENT)
ierr(file->file_name);
ev_change++;
}
}
}
for (i = 0, file = files; i < no_files; i++, file++)
if (file->fp && !show(file))
ev_change++;
if (ev_change)
set_events(files);
switch (action) {
case USE_KQUEUE:
ts.tv_sec = 1;
ts.tv_nsec = 0;
/*
* In the -F case we set a timeout to ensure that
* we re-stat the file at least once every second.
*/
n = kevent(kq, NULL, 0, ev, 1, Fflag ? &ts : NULL);
if (n < 0)
err(1, "kevent");
if (n == 0) {
/* timeout */
break;
} else if (ev->filter == EVFILT_READ && ev->data < 0) {
/* file shrank, reposition to end */
if (lseek(ev->ident, (off_t)0, SEEK_END) == -1) {
ierr(file->file_name);
continue;
}
}
break;
case USE_SLEEP:
(void) usleep(250000);
break;
}
}
}
