2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * Edward Sze-Tyan Wang.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 4. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 static char sccsid[] = "@(#)reverse.c 8.1 (Berkeley) 6/6/93";
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD$");
42 #include <sys/param.h>
43 #include <sys/queue.h>
58 static void r_buf(FILE *, const char *);
59 static void r_reg(FILE *, const char *, enum STYLE, off_t, struct stat *);
62 * reverse -- display input in reverse order by line.
64 * There are six separate cases for this -- regular and non-regular
65 * files by bytes, lines or the whole file.
67 * BYTES display N bytes
68 * REG mmap the file and display the lines
69 * NOREG cyclically read characters into a wrap-around buffer
71 * LINES display N lines
72 * REG mmap the file and display the lines
73 * NOREG cyclically read lines into a wrap-around array of buffers
75 * FILE display the entire file
76 * REG mmap the file and display the lines
77 * NOREG cyclically read input into a linked list of buffers
80 reverse(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
82 if (style != REVERSE && off == 0)
85 if (S_ISREG(sbp->st_mode))
86 r_reg(fp, fn, style, off, sbp);
106 * r_reg -- display a regular file in reverse order by line.
109 r_reg(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
112 off_t curoff, size, lineend;
115 if (!(size = sbp->st_size))
119 map.mapoff = map.maxoff = size;
124 * Last char is special, ignore whether newline or not. Note that
125 * size == 0 is dealt with above, and size == 1 sets curoff to -1.
129 while (curoff >= 0) {
130 if (curoff < map.mapoff ||
131 curoff >= map.mapoff + (off_t)map.maplen) {
132 if (maparound(&map, curoff) != 0) {
137 for (i = curoff - map.mapoff; i >= 0; i--) {
138 if (style == RBYTES && --off == 0)
140 if (map.start[i] == '\n')
143 /* `i' is either the map offset of a '\n', or -1. */
144 curoff = map.mapoff + i;
148 /* Print the line and update offsets. */
149 if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) {
153 lineend = curoff + 1;
159 if (off == 0 && style != REVERSE) {
160 /* Avoid printing anything below. */
165 if (curoff < 0 && mapprint(&map, 0, lineend) != 0) {
169 if (map.start != NULL && munmap(map.start, map.maplen))
173 #define BSZ (128 * 1024)
174 typedef struct bfelem {
175 TAILQ_ENTRY(bfelem) entries;
181 * r_buf -- display a non-regular file in reverse order by line.
183 * This is the function that saves the entire input, storing the data in a
184 * doubly linked list of buffers and then displays them in reverse order.
185 * It has the usual nastiness of trying to find the newlines, as there's no
186 * guarantee that a newline occurs anywhere in the file, let alone in any
187 * particular buffer. If we run out of memory, input is discarded (and the
191 r_buf(FILE *fp, const char *fn)
193 struct bfelem *tl, *first = NULL;
197 TAILQ_HEAD(bfhead, bfelem) head;
205 * Allocate a new block and link it into place in a doubly
206 * linked list. If out of memory, toss the LRU block and
209 while ((tl = malloc(sizeof(bfelem_t))) == NULL) {
210 first = TAILQ_FIRST(&head);
211 if (TAILQ_EMPTY(&head))
213 enomem += first->len;
214 TAILQ_REMOVE(&head, first, entries);
217 TAILQ_INSERT_TAIL(&head, tl, entries);
219 /* Fill the block with input data. */
221 while ((!feof(fp)) && len < BSZ) {
223 len += fread(p, 1, BSZ - len, fp);
234 warnx("warning: %jd bytes discarded", (intmax_t)enomem);
239 * Now print the lines in reverse order
241 * Scan backward for "\n",
242 * print forward to the end of the buffers
243 * free any buffers that start after the "\n" just found
246 tl = TAILQ_LAST(&head, bfhead);
247 first = TAILQ_FIRST(&head);
251 for (p = tl->l + tl->len - 1, llen = 0; p >= tl->l;
253 int start = (tl == first && p == tl->l);
255 if ((*p == '\n') || start) {
258 if (llen && start && *p != '\n')
262 if (start && *p == '\n')
265 tr = TAILQ_NEXT(tl, entries);
268 TAILQ_FOREACH_FROM_SAFE(tr, &head,
272 TAILQ_REMOVE(&head, tr,
280 tl = TAILQ_PREV(tl, bfhead, entries);
282 TAILQ_REMOVE(&head, first, entries);