2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
7 * This code is derived from software contributed to Berkeley by
8 * Edward Sze-Tyan Wang.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 static char sccsid[] = "@(#)reverse.c 8.1 (Berkeley) 6/6/93";
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD$");
44 #include <sys/param.h>
45 #include <sys/queue.h>
60 static void r_buf(FILE *, const char *);
61 static void r_reg(FILE *, const char *, enum STYLE, off_t, struct stat *);
64 * reverse -- display input in reverse order by line.
66 * There are six separate cases for this -- regular and non-regular
67 * files by bytes, lines or the whole file.
69 * BYTES display N bytes
70 * REG mmap the file and display the lines
71 * NOREG cyclically read characters into a wrap-around buffer
73 * LINES display N lines
74 * REG mmap the file and display the lines
75 * NOREG cyclically read lines into a wrap-around array of buffers
77 * FILE display the entire file
78 * REG mmap the file and display the lines
79 * NOREG cyclically read input into a linked list of buffers
82 reverse(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
84 if (style != REVERSE && off == 0)
87 if (S_ISREG(sbp->st_mode))
88 r_reg(fp, fn, style, off, sbp);
108 * r_reg -- display a regular file in reverse order by line.
111 r_reg(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
114 off_t curoff, size, lineend;
117 if (!(size = sbp->st_size))
121 map.mapoff = map.maxoff = size;
126 * Last char is special, ignore whether newline or not. Note that
127 * size == 0 is dealt with above, and size == 1 sets curoff to -1.
131 while (curoff >= 0) {
132 if (curoff < map.mapoff ||
133 curoff >= map.mapoff + (off_t)map.maplen) {
134 if (maparound(&map, curoff) != 0) {
139 for (i = curoff - map.mapoff; i >= 0; i--) {
140 if (style == RBYTES && --off == 0)
142 if (map.start[i] == '\n')
145 /* `i' is either the map offset of a '\n', or -1. */
146 curoff = map.mapoff + i;
150 /* Print the line and update offsets. */
151 if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) {
155 lineend = curoff + 1;
161 if (off == 0 && style != REVERSE) {
162 /* Avoid printing anything below. */
167 if (curoff < 0 && mapprint(&map, 0, lineend) != 0) {
171 if (map.start != NULL && munmap(map.start, map.maplen))
175 #define BSZ (128 * 1024)
176 typedef struct bfelem {
177 TAILQ_ENTRY(bfelem) entries;
183 * r_buf -- display a non-regular file in reverse order by line.
185 * This is the function that saves the entire input, storing the data in a
186 * doubly linked list of buffers and then displays them in reverse order.
187 * It has the usual nastiness of trying to find the newlines, as there's no
188 * guarantee that a newline occurs anywhere in the file, let alone in any
189 * particular buffer. If we run out of memory, input is discarded (and the
193 r_buf(FILE *fp, const char *fn)
195 struct bfelem *tl, *first = NULL;
199 TAILQ_HEAD(bfhead, bfelem) head;
207 * Allocate a new block and link it into place in a doubly
208 * linked list. If out of memory, toss the LRU block and
211 while ((tl = malloc(sizeof(bfelem_t))) == NULL) {
212 first = TAILQ_FIRST(&head);
213 if (TAILQ_EMPTY(&head))
215 enomem += first->len;
216 TAILQ_REMOVE(&head, first, entries);
219 TAILQ_INSERT_TAIL(&head, tl, entries);
221 /* Fill the block with input data. */
223 while ((!feof(fp)) && len < BSZ) {
225 len += fread(p, 1, BSZ - len, fp);
236 warnx("warning: %jd bytes discarded", (intmax_t)enomem);
241 * Now print the lines in reverse order
243 * Scan backward for "\n",
244 * print forward to the end of the buffers
245 * free any buffers that start after the "\n" just found
248 tl = TAILQ_LAST(&head, bfhead);
249 first = TAILQ_FIRST(&head);
253 for (p = tl->l + tl->len - 1, llen = 0; p >= tl->l;
255 int start = (tl == first && p == tl->l);
257 if ((*p == '\n') || start) {
260 if (llen && start && *p != '\n')
264 if (start && *p == '\n')
267 tr = TAILQ_NEXT(tl, entries);
270 TAILQ_FOREACH_FROM_SAFE(tr, &head,
274 TAILQ_REMOVE(&head, tr,
282 tl = TAILQ_PREV(tl, bfhead, entries);
284 TAILQ_REMOVE(&head, first, entries);