322 lines
7.4 KiB
C
322 lines
7.4 KiB
C
/*-
|
|
* 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. All advertising materials mentioning features or use of this software
|
|
* must display the following acknowledgement:
|
|
* This product includes software developed by the University of
|
|
* California, Berkeley and its contributors.
|
|
* 4. 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/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 __P((FILE *, off_t, struct stat *));
|
|
|
|
/* defines for inner loop actions */
|
|
#define USE_SLEEP 0
|
|
#define USE_KQUEUE 1
|
|
#define ADD_EVENTS 2
|
|
|
|
/*
|
|
* 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(fp, style, off, sbp)
|
|
FILE *fp;
|
|
enum STYLE style;
|
|
off_t off;
|
|
struct stat *sbp;
|
|
{
|
|
int ch, n, kq = -1;
|
|
int action = USE_SLEEP;
|
|
struct kevent ev[2];
|
|
struct stat sb2;
|
|
struct timespec ts;
|
|
|
|
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();
|
|
return;
|
|
}
|
|
} else while (off--)
|
|
if ((ch = getc(fp)) == EOF) {
|
|
if (ferror(fp)) {
|
|
ierr();
|
|
return;
|
|
}
|
|
break;
|
|
}
|
|
break;
|
|
case FLINES:
|
|
if (off == 0)
|
|
break;
|
|
for (;;) {
|
|
if ((ch = getc(fp)) == EOF) {
|
|
if (ferror(fp)) {
|
|
ierr();
|
|
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();
|
|
return;
|
|
}
|
|
} else if (off == 0) {
|
|
while (getc(fp) != EOF);
|
|
if (ferror(fp)) {
|
|
ierr();
|
|
return;
|
|
}
|
|
} else
|
|
if (bytes(fp, off))
|
|
return;
|
|
break;
|
|
case RLINES:
|
|
if (S_ISREG(sbp->st_mode))
|
|
if (!off) {
|
|
if (fseeko(fp, (off_t)0, SEEK_END) == -1) {
|
|
ierr();
|
|
return;
|
|
}
|
|
} else
|
|
rlines(fp, off, sbp);
|
|
else if (off == 0) {
|
|
while (getc(fp) != EOF);
|
|
if (ferror(fp)) {
|
|
ierr();
|
|
return;
|
|
}
|
|
} else
|
|
if (lines(fp, off))
|
|
return;
|
|
break;
|
|
default:
|
|
}
|
|
|
|
if (fflag) {
|
|
kq = kqueue();
|
|
if (kq < 0)
|
|
err(1, "kqueue");
|
|
action = ADD_EVENTS;
|
|
}
|
|
|
|
for (;;) {
|
|
while ((ch = getc(fp)) != EOF)
|
|
if (putchar(ch) == EOF)
|
|
oerr();
|
|
if (ferror(fp)) {
|
|
ierr();
|
|
return;
|
|
}
|
|
(void)fflush(stdout);
|
|
if (! fflag)
|
|
break;
|
|
clearerr(fp);
|
|
|
|
switch (action) {
|
|
case ADD_EVENTS:
|
|
n = 0;
|
|
ts.tv_sec = 0;
|
|
ts.tv_nsec = 0;
|
|
|
|
if (Fflag && fileno(fp) != STDIN_FILENO) {
|
|
EV_SET(&ev[n], fileno(fp), EVFILT_VNODE,
|
|
EV_ADD | EV_ENABLE | EV_CLEAR,
|
|
NOTE_DELETE | NOTE_RENAME, 0, 0);
|
|
n++;
|
|
}
|
|
EV_SET(&ev[n], fileno(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;
|
|
} else {
|
|
action = USE_KQUEUE;
|
|
}
|
|
break;
|
|
|
|
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 (fseeko(fp, (off_t)0, SEEK_END) == -1) {
|
|
ierr();
|
|
return;
|
|
}
|
|
}
|
|
break;
|
|
|
|
case USE_SLEEP:
|
|
(void) usleep(250000);
|
|
clearerr(fp);
|
|
break;
|
|
}
|
|
|
|
if (Fflag && fileno(fp) != STDIN_FILENO) {
|
|
while (stat(fname, &sb2) != 0)
|
|
/* file was rotated, wait until it reappears */
|
|
(void)sleep(1);
|
|
if (sb2.st_ino != sbp->st_ino ||
|
|
sb2.st_dev != sbp->st_dev ||
|
|
sb2.st_rdev != sbp->st_rdev ||
|
|
sb2.st_nlink == 0) {
|
|
fp = freopen(fname, "r", fp);
|
|
if (fp == NULL) {
|
|
ierr();
|
|
} else {
|
|
*sbp = sb2;
|
|
action = ADD_EVENTS;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* rlines -- display the last offset lines of the file.
|
|
*/
|
|
static void
|
|
rlines(fp, off, sbp)
|
|
FILE *fp;
|
|
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();
|
|
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();
|
|
exit(1);
|
|
}
|
|
|
|
/* Set the file pointer to reflect the length displayed. */
|
|
if (fseeko(fp, sbp->st_size, SEEK_SET) == -1) {
|
|
ierr();
|
|
return;
|
|
}
|
|
if (map.start != NULL && munmap(map.start, map.maplen)) {
|
|
ierr();
|
|
return;
|
|
}
|
|
}
|