freebsd-dev/usr.bin/tail/reverse.c
Warner Losh fbbd9655e5 Renumber copyright clause 4
Renumber cluase 4 to 3, per what everybody else did when BSD granted
them permission to remove clause 3. My insistance on keeping the same
numbering for legal reasons is too pedantic, so give up on that point.

Submitted by:	Jan Schaumann <jschauma@stevens.edu>
Pull Request:	https://github.com/freebsd/freebsd/pull/96
2017-02-28 23:42:47 +00:00

282 lines
7.0 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. 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.
*/
#if 0
#ifndef lint
static char sccsid[] = "@(#)reverse.c 8.1 (Berkeley) 6/6/93";
#endif /* not lint */
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/stat.h>
#include <sys/mman.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "extern.h"
static void r_buf(FILE *, const char *);
static void r_reg(FILE *, const char *, enum STYLE, off_t, struct stat *);
/*
* reverse -- display input in reverse order by line.
*
* There are six separate cases for this -- regular and non-regular
* files by bytes, lines or the whole file.
*
* BYTES display N bytes
* REG mmap the file and display the lines
* NOREG cyclically read characters into a wrap-around buffer
*
* LINES display N lines
* REG mmap the file and display the lines
* NOREG cyclically read lines into a wrap-around array of buffers
*
* FILE display the entire file
* REG mmap the file and display the lines
* NOREG cyclically read input into a linked list of buffers
*/
void
reverse(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
{
if (style != REVERSE && off == 0)
return;
if (S_ISREG(sbp->st_mode))
r_reg(fp, fn, style, off, sbp);
else
switch(style) {
case FBYTES:
case RBYTES:
bytes(fp, fn, off);
break;
case FLINES:
case RLINES:
lines(fp, fn, off);
break;
case REVERSE:
r_buf(fp, fn);
break;
default:
break;
}
}
/*
* r_reg -- display a regular file in reverse order by line.
*/
static void
r_reg(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
{
struct mapinfo map;
off_t curoff, size, lineend;
int i;
if (!(size = sbp->st_size))
return;
map.start = NULL;
map.mapoff = map.maxoff = size;
map.fd = fileno(fp);
map.maplen = 0;
/*
* 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;
lineend = size;
while (curoff >= 0) {
if (curoff < map.mapoff ||
curoff >= map.mapoff + (off_t)map.maplen) {
if (maparound(&map, curoff) != 0) {
ierr(fn);
return;
}
}
for (i = curoff - map.mapoff; i >= 0; i--) {
if (style == RBYTES && --off == 0)
break;
if (map.start[i] == '\n')
break;
}
/* `i' is either the map offset of a '\n', or -1. */
curoff = map.mapoff + i;
if (i < 0)
continue;
/* Print the line and update offsets. */
if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) {
ierr(fn);
return;
}
lineend = curoff + 1;
curoff--;
if (style == RLINES)
off--;
if (off == 0 && style != REVERSE) {
/* Avoid printing anything below. */
curoff = 0;
break;
}
}
if (curoff < 0 && mapprint(&map, 0, lineend) != 0) {
ierr(fn);
return;
}
if (map.start != NULL && munmap(map.start, map.maplen))
ierr(fn);
}
#define BSZ (128 * 1024)
typedef struct bfelem {
TAILQ_ENTRY(bfelem) entries;
size_t len;
char l[BSZ];
} bfelem_t;
/*
* r_buf -- display a non-regular file in reverse order by line.
*
* This is the function that saves the entire input, storing the data in a
* doubly linked list of buffers and then displays them in reverse order.
* It has the usual nastiness of trying to find the newlines, as there's no
* guarantee that a newline occurs anywhere in the file, let alone in any
* particular buffer. If we run out of memory, input is discarded (and the
* user warned).
*/
static void
r_buf(FILE *fp, const char *fn)
{
struct bfelem *tl, *first = NULL;
size_t llen;
char *p;
off_t enomem = 0;
TAILQ_HEAD(bfhead, bfelem) head;
TAILQ_INIT(&head);
while (!feof(fp)) {
size_t len;
/*
* Allocate a new block and link it into place in a doubly
* linked list. If out of memory, toss the LRU block and
* keep going.
*/
while ((tl = malloc(sizeof(bfelem_t))) == NULL) {
first = TAILQ_FIRST(&head);
if (TAILQ_EMPTY(&head))
err(1, "malloc");
enomem += first->len;
TAILQ_REMOVE(&head, first, entries);
free(first);
}
TAILQ_INSERT_TAIL(&head, tl, entries);
/* Fill the block with input data. */
len = 0;
while ((!feof(fp)) && len < BSZ) {
p = tl->l + len;
len += fread(p, 1, BSZ - len, fp);
if (ferror(fp)) {
ierr(fn);
return;
}
}
tl->len = len;
}
if (enomem) {
warnx("warning: %jd bytes discarded", (intmax_t)enomem);
rval = 1;
}
/*
* Now print the lines in reverse order
* Outline:
* Scan backward for "\n",
* print forward to the end of the buffers
* free any buffers that start after the "\n" just found
* Loop
*/
tl = TAILQ_LAST(&head, bfhead);
first = TAILQ_FIRST(&head);
while (tl != NULL) {
struct bfelem *temp;
for (p = tl->l + tl->len - 1, llen = 0; p >= tl->l;
--p, ++llen) {
int start = (tl == first && p == tl->l);
if ((*p == '\n') || start) {
struct bfelem *tr;
if (start && llen)
WR(p, llen + 1);
else if (llen)
WR(p + 1, llen);
tr = TAILQ_NEXT(tl, entries);
llen = 0;
if (tr != NULL) {
TAILQ_FOREACH_FROM_SAFE(tr, &head,
entries, temp) {
if (tr->len)
WR(&tr->l, tr->len);
TAILQ_REMOVE(&head, tr,
entries);
free(tr);
}
}
}
}
tl->len = llen;
tl = TAILQ_PREV(tl, bfhead, entries);
}
TAILQ_REMOVE(&head, first, entries);
free(first);
}