File: [local] / src / usr.bin / tail / forward.c (download)
Revision 1.33, Fri Jun 28 13:35:04 2019 UTC (4 years, 11 months ago) by deraadt
Branch: MAIN
CVS Tags: OPENBSD_7_5_BASE, OPENBSD_7_5, OPENBSD_7_4_BASE, OPENBSD_7_4, OPENBSD_7_3_BASE, OPENBSD_7_3, OPENBSD_7_2_BASE, OPENBSD_7_2, OPENBSD_7_1_BASE, OPENBSD_7_1, OPENBSD_7_0_BASE, OPENBSD_7_0, OPENBSD_6_9_BASE, OPENBSD_6_9, OPENBSD_6_8_BASE, OPENBSD_6_8, OPENBSD_6_7_BASE, OPENBSD_6_7, OPENBSD_6_6_BASE, OPENBSD_6_6, HEAD Changes since 1.32: +4 -4 lines
When system calls indicate an error they return -1, not some arbitrary
value < 0. errno is only updated in this case. Change all (most?)
callers of syscalls to follow this better, and let's see if this strictness
helps us in the future.
|
/* $OpenBSD: forward.c,v 1.33 2019/06/28 13:35:04 deraadt Exp $ */
/* $NetBSD: forward.c,v 1.7 1996/02/13 16:49:10 ghudson Exp $ */
/*-
* 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/types.h>
#include <sys/stat.h>
#include <sys/event.h>
#include <err.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "extern.h"
static int rlines(struct tailfile *, off_t);
static inline void tfprint(FILE *fp);
static int tfqueue(struct tailfile *tf);
static const struct timespec *tfreopen(struct tailfile *tf);
static int kq = -1;
/*
* 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 step back until the correct offset is reached.
* NOREG cyclically read lines into a wrap-around array of buffers
*/
void
forward(struct tailfile *tf, int nfiles, enum STYLE style, off_t origoff)
{
int ch;
struct tailfile *ctf, *ltf;
struct kevent ke;
const struct timespec *ts = NULL;
int i;
int nevents;
if (nfiles < 1)
return;
if (fflag && (kq = kqueue()) == -1)
warn("kqueue");
for (i = 0; i < nfiles; i++) {
off_t off = origoff;
if (nfiles > 1)
printfname(tf[i].fname);
switch(style) {
case FBYTES:
if (off == 0)
break;
if (S_ISREG(tf[i].sb.st_mode)) {
if (tf[i].sb.st_size < off)
off = tf[i].sb.st_size;
if (fseeko(tf[i].fp, off, SEEK_SET) == -1) {
ierr(tf[i].fname);
return;
}
} else while (off--)
if ((ch = getc(tf[i].fp)) == EOF) {
if (ferror(tf[i].fp)) {
ierr(tf[i].fname);
return;
}
break;
}
break;
case FLINES:
if (off == 0)
break;
for (;;) {
if ((ch = getc(tf[i].fp)) == EOF) {
if (ferror(tf[i].fp)) {
ierr(tf[i].fname);
return;
}
break;
}
if (ch == '\n' && !--off)
break;
}
break;
case RBYTES:
if (S_ISREG(tf[i].sb.st_mode)) {
if (tf[i].sb.st_size >= off &&
fseeko(tf[i].fp, -off, SEEK_END) == -1) {
ierr(tf[i].fname);
return;
}
} else if (off == 0) {
while (getc(tf[i].fp) != EOF)
;
if (ferror(tf[i].fp)) {
ierr(tf[i].fname);
return;
}
} else {
if (bytes(&(tf[i]), off))
return;
}
break;
case RLINES:
if (S_ISREG(tf[i].sb.st_mode)) {
if (!off) {
if (fseeko(tf[i].fp, (off_t)0,
SEEK_END) == -1) {
ierr(tf[i].fname);
return;
}
} else if (rlines(&(tf[i]), off) != 0)
lines(&(tf[i]), off);
} else if (off == 0) {
while (getc(tf[i].fp) != EOF)
;
if (ferror(tf[i].fp)) {
ierr(tf[i].fname);
return;
}
} else {
if (lines(&(tf[i]), off))
return;
}
break;
default:
err(1, "Unsupported style");
}
tfprint(tf[i].fp);
if (fflag && tfqueue(&(tf[i])) == -1)
warn("Unable to follow %s", tf[i].fname);
}
ltf = &(tf[i-1]);
(void)fflush(stdout);
if (!fflag || kq == -1)
return;
while (1) {
if ((nevents = kevent(kq, NULL, 0, &ke, 1, ts)) <= 0) {
if (errno == EINTR) {
close(kq);
return;
}
}
ctf = ke.udata;
if (nevents > 0) {
if (ke.filter == EVFILT_READ) {
if (ctf != ltf) {
printfname(ctf->fname);
ltf = ctf;
}
clearerr(ctf->fp);
tfprint(ctf->fp);
if (ferror(ctf->fp)) {
ierr(ctf->fname);
fclose(ctf->fp);
warn("Lost file %s", ctf->fname);
continue;
}
(void)fflush(stdout);
clearerr(ctf->fp);
} else if (ke.filter == EVFILT_VNODE) {
if (ke.fflags & (NOTE_DELETE | NOTE_RENAME)) {
/*
* File was deleted or renamed.
*
* Continue to look at it until
* a new file reappears with
* the same name.
*/
(void) tfreopen(ctf);
} else if (ke.fflags & NOTE_TRUNCATE) {
warnx("%s has been truncated, "
"resetting.", ctf->fname);
fpurge(ctf->fp);
rewind(ctf->fp);
}
}
}
ts = tfreopen(NULL);
}
}
/*
* rlines -- display the last offset lines of the file.
*/
static int
rlines(struct tailfile *tf, off_t off)
{
off_t pos;
int ch;
pos = tf->sb.st_size;
if (pos == 0)
return (0);
/*
* Position before char.
* Last char is special, ignore it whether newline or not.
*/
pos -= 2;
ch = EOF;
for (; off > 0 && pos >= 0; pos--) {
/* A seek per char isn't a problem with a smart stdio */
if (fseeko(tf[0].fp, pos, SEEK_SET) == -1) {
ierr(tf->fname);
return (1);
}
if ((ch = getc(tf[0].fp)) == '\n')
off--;
else if (ch == EOF) {
if (ferror(tf[0].fp)) {
ierr(tf->fname);
return (1);
}
break;
}
}
/* If we read until start of file, put back last read char */
if (pos < 0 && off > 0 && ch != EOF && ungetc(ch, tf[0].fp) == EOF) {
ierr(tf->fname);
return (1);
}
while (!feof(tf[0].fp) && (ch = getc(tf[0].fp)) != EOF)
if (putchar(ch) == EOF)
oerr();
if (ferror(tf[0].fp)) {
ierr(tf->fname);
return (1);
}
return (0);
}
static inline void
tfprint(FILE *fp)
{
int ch;
while (!feof(fp) && (ch = getc(fp)) != EOF)
if (putchar(ch) == EOF)
oerr();
}
static int
tfqueue(struct tailfile *tf)
{
struct kevent ke[2];
int i = 1;
if (kq < 0) {
errno = EBADF;
return -1;
}
EV_SET(&(ke[0]), fileno(tf->fp), EVFILT_READ,
EV_ENABLE | EV_ADD | EV_CLEAR, 0, 0, tf);
if (S_ISREG(tf->sb.st_mode)) {
i = 2;
EV_SET(&(ke[1]), fileno(tf->fp), EVFILT_VNODE,
EV_ENABLE | EV_ADD | EV_CLEAR,
NOTE_DELETE | NOTE_RENAME | NOTE_TRUNCATE,
0, tf);
}
if (kevent(kq, ke, i, NULL, 0, NULL) == -1) {
ierr(tf->fname);
return -1;
}
return 0;
}
#define AFILESINCR 8
static const struct timespec *
tfreopen(struct tailfile *tf) {
static struct tailfile **reopen = NULL;
static int nfiles = 0, afiles = 0;
static const struct timespec ts = {1, 0};
struct stat sb;
struct tailfile **treopen, *ttf;
int i;
if (tf && !(tf->fp == stdin) &&
((stat(tf->fname, &sb) != 0) || sb.st_ino != tf->sb.st_ino)) {
if (afiles < ++nfiles) {
afiles += AFILESINCR;
treopen = reallocarray(reopen, afiles, sizeof(*reopen));
if (treopen)
reopen = treopen;
else
afiles -= AFILESINCR;
}
if (nfiles <= afiles) {
for (i = 0; i < nfiles - 1; i++)
if (strcmp(reopen[i]->fname, tf->fname) == 0)
break;
if (i < nfiles - 1)
nfiles--;
else
reopen[nfiles-1] = tf;
} else {
warnx("Lost track of %s", tf->fname);
nfiles--;
}
}
for (i = 0; i < nfiles; i++) {
ttf = reopen[i];
if (stat(ttf->fname, &sb) == -1)
continue;
if (sb.st_ino != ttf->sb.st_ino) {
(void) memcpy(&(ttf->sb), &sb, sizeof(ttf->sb));
ttf->fp = freopen(ttf->fname, "r", ttf->fp);
if (ttf->fp == NULL)
ierr(ttf->fname);
else {
warnx("%s has been replaced, reopening.",
ttf->fname);
tfqueue(ttf);
}
}
reopen[i] = reopen[--nfiles];
}
return nfiles ? &ts : NULL;
}