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>
58 #include <libcasper.h>
59 #include <casper/cap_fileargs.h>
63 static void r_buf(FILE *, const char *);
64 static void r_reg(FILE *, const char *, enum STYLE, off_t, struct stat *);
67 * reverse -- display input in reverse order by line.
69 * There are six separate cases for this -- regular and non-regular
70 * files by bytes, lines or the whole file.
72 * BYTES display N bytes
73 * REG mmap the file and display the lines
74 * NOREG cyclically read characters into a wrap-around buffer
76 * LINES display N lines
77 * REG mmap the file and display the lines
78 * NOREG cyclically read lines into a wrap-around array of buffers
80 * FILE display the entire file
81 * REG mmap the file and display the lines
82 * NOREG cyclically read input into a linked list of buffers
85 reverse(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
87 if (style != REVERSE && off == 0)
90 if (S_ISREG(sbp->st_mode))
91 r_reg(fp, fn, style, off, sbp);
111 * r_reg -- display a regular file in reverse order by line.
114 r_reg(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
117 off_t curoff, size, lineend;
120 if (!(size = sbp->st_size))
124 map.mapoff = map.maxoff = size;
129 * Last char is special, ignore whether newline or not. Note that
130 * size == 0 is dealt with above, and size == 1 sets curoff to -1.
134 while (curoff >= 0) {
135 if (curoff < map.mapoff ||
136 curoff >= map.mapoff + (off_t)map.maplen) {
137 if (maparound(&map, curoff) != 0) {
142 for (i = curoff - map.mapoff; i >= 0; i--) {
143 if (style == RBYTES && --off == 0)
145 if (map.start[i] == '\n')
148 /* `i' is either the map offset of a '\n', or -1. */
149 curoff = map.mapoff + i;
153 /* Print the line and update offsets. */
154 if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) {
158 lineend = curoff + 1;
164 if (off == 0 && style != REVERSE) {
165 /* Avoid printing anything below. */
170 if (curoff < 0 && mapprint(&map, 0, lineend) != 0) {
174 if (map.start != NULL && munmap(map.start, map.maplen))
178 #define BSZ (128 * 1024)
179 typedef struct bfelem {
180 TAILQ_ENTRY(bfelem) entries;
186 * r_buf -- display a non-regular file in reverse order by line.
188 * This is the function that saves the entire input, storing the data in a
189 * doubly linked list of buffers and then displays them in reverse order.
190 * It has the usual nastiness of trying to find the newlines, as there's no
191 * guarantee that a newline occurs anywhere in the file, let alone in any
192 * particular buffer. If we run out of memory, input is discarded (and the
196 r_buf(FILE *fp, const char *fn)
198 struct bfelem *tl, *first = NULL;
202 TAILQ_HEAD(bfhead, bfelem) head;
210 * Allocate a new block and link it into place in a doubly
211 * linked list. If out of memory, toss the LRU block and
214 while ((tl = malloc(sizeof(bfelem_t))) == NULL) {
215 first = TAILQ_FIRST(&head);
216 if (TAILQ_EMPTY(&head))
218 enomem += first->len;
219 TAILQ_REMOVE(&head, first, entries);
222 TAILQ_INSERT_TAIL(&head, tl, entries);
224 /* Fill the block with input data. */
226 while ((!feof(fp)) && len < BSZ) {
228 len += fread(p, 1, BSZ - len, fp);
239 warnx("warning: %jd bytes discarded", (intmax_t)enomem);
244 * Now print the lines in reverse order
246 * Scan backward for "\n",
247 * print forward to the end of the buffers
248 * free any buffers that start after the "\n" just found
251 tl = TAILQ_LAST(&head, bfhead);
252 first = TAILQ_FIRST(&head);
256 for (p = tl->l + tl->len - 1, llen = 0; p >= tl->l;
258 int start = (tl == first && p == tl->l);
260 if ((*p == '\n') || start) {
263 if (llen && start && *p != '\n')
267 if (start && *p == '\n')
270 tr = TAILQ_NEXT(tl, entries);
273 TAILQ_FOREACH_FROM_SAFE(tr, &head,
277 TAILQ_REMOVE(&head, tr,
285 tl = TAILQ_PREV(tl, bfhead, entries);
287 TAILQ_REMOVE(&head, first, entries);