/*-
* 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.
*/
#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 (llen && start && *p != '\n')
WR(p, llen + 1);
else if (llen) {
WR(p + 1, llen);
if (start && *p == '\n')
WR(p, 1);
}
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);
}
