1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Edward Sze-Tyan Wang.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
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.
21 *
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
32 * SUCH DAMAGE.
33 */
34
35 #if 0
36 #ifndef lint
37 static char sccsid[] = "@(#)reverse.c 8.1 (Berkeley) 6/6/93";
38 #endif /* not lint */
39 #endif
40
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD$");
43
44 #include <sys/param.h>
45 #include <sys/queue.h>
46 #include <sys/stat.h>
47 #include <sys/mman.h>
48
49 #include <err.h>
50 #include <errno.h>
51 #include <limits.h>
52 #include <stdint.h>
53 #include <stdio.h>
54 #include <stdlib.h>
55 #include <string.h>
56 #include <unistd.h>
57
58 #include <libcasper.h>
59 #include <casper/cap_fileargs.h>
60
61 #include "extern.h"
62
63 static void r_buf(FILE *, const char *);
64 static void r_reg(FILE *, const char *, enum STYLE, off_t, struct stat *);
65
66 /*
67 * reverse -- display input in reverse order by line.
68 *
69 * There are six separate cases for this -- regular and non-regular
70 * files by bytes, lines or the whole file.
71 *
72 * BYTES display N bytes
73 * REG mmap the file and display the lines
74 * NOREG cyclically read characters into a wrap-around buffer
75 *
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
79 *
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
83 */
84 void
reverse(FILE * fp,const char * fn,enum STYLE style,off_t off,struct stat * sbp)85 reverse(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
86 {
87 if (style != REVERSE && off == 0)
88 return;
89
90 if (S_ISREG(sbp->st_mode))
91 r_reg(fp, fn, style, off, sbp);
92 else
93 switch(style) {
94 case FBYTES:
95 case RBYTES:
96 bytes(fp, fn, off);
97 break;
98 case FLINES:
99 case RLINES:
100 lines(fp, fn, off);
101 break;
102 case REVERSE:
103 r_buf(fp, fn);
104 break;
105 default:
106 break;
107 }
108 }
109
110 /*
111 * r_reg -- display a regular file in reverse order by line.
112 */
113 static void
r_reg(FILE * fp,const char * fn,enum STYLE style,off_t off,struct stat * sbp)114 r_reg(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
115 {
116 struct mapinfo map;
117 off_t curoff, size, lineend;
118 int i;
119
120 if (!(size = sbp->st_size))
121 return;
122
123 map.start = NULL;
124 map.mapoff = map.maxoff = size;
125 map.fd = fileno(fp);
126 map.maplen = 0;
127
128 /*
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.
131 */
132 curoff = size - 2;
133 lineend = size;
134 while (curoff >= 0) {
135 if (curoff < map.mapoff ||
136 curoff >= map.mapoff + (off_t)map.maplen) {
137 if (maparound(&map, curoff) != 0) {
138 ierr(fn);
139 return;
140 }
141 }
142 for (i = curoff - map.mapoff; i >= 0; i--) {
143 if (style == RBYTES && --off == 0)
144 break;
145 if (map.start[i] == '\n')
146 break;
147 }
148 /* `i' is either the map offset of a '\n', or -1. */
149 curoff = map.mapoff + i;
150 if (i < 0)
151 continue;
152
153 /* Print the line and update offsets. */
154 if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) {
155 ierr(fn);
156 return;
157 }
158 lineend = curoff + 1;
159 curoff--;
160
161 if (style == RLINES)
162 off--;
163
164 if (off == 0 && style != REVERSE) {
165 /* Avoid printing anything below. */
166 curoff = 0;
167 break;
168 }
169 }
170 if (curoff < 0 && mapprint(&map, 0, lineend) != 0) {
171 ierr(fn);
172 return;
173 }
174 if (map.start != NULL && munmap(map.start, map.maplen))
175 ierr(fn);
176 }
177
178 #define BSZ (128 * 1024)
179 typedef struct bfelem {
180 TAILQ_ENTRY(bfelem) entries;
181 size_t len;
182 char l[BSZ];
183 } bfelem_t;
184
185 /*
186 * r_buf -- display a non-regular file in reverse order by line.
187 *
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
193 * user warned).
194 */
195 static void
r_buf(FILE * fp,const char * fn)196 r_buf(FILE *fp, const char *fn)
197 {
198 struct bfelem *tl, *first = NULL;
199 size_t llen;
200 char *p;
201 off_t enomem = 0;
202 TAILQ_HEAD(bfhead, bfelem) head;
203
204 TAILQ_INIT(&head);
205
206 while (!feof(fp)) {
207 size_t len;
208
209 /*
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
212 * keep going.
213 */
214 while ((tl = malloc(sizeof(bfelem_t))) == NULL) {
215 first = TAILQ_FIRST(&head);
216 if (TAILQ_EMPTY(&head))
217 err(1, "malloc");
218 enomem += first->len;
219 TAILQ_REMOVE(&head, first, entries);
220 free(first);
221 }
222 TAILQ_INSERT_TAIL(&head, tl, entries);
223
224 /* Fill the block with input data. */
225 len = 0;
226 while ((!feof(fp)) && len < BSZ) {
227 p = tl->l + len;
228 len += fread(p, 1, BSZ - len, fp);
229 if (ferror(fp)) {
230 ierr(fn);
231 return;
232 }
233 }
234
235 tl->len = len;
236 }
237
238 if (enomem) {
239 warnx("warning: %jd bytes discarded", (intmax_t)enomem);
240 rval = 1;
241 }
242
243 /*
244 * Now print the lines in reverse order
245 * Outline:
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
249 * Loop
250 */
251 tl = TAILQ_LAST(&head, bfhead);
252 first = TAILQ_FIRST(&head);
253 while (tl != NULL) {
254 struct bfelem *temp;
255
256 for (p = tl->l + tl->len - 1, llen = 0; p >= tl->l;
257 --p, ++llen) {
258 int start = (tl == first && p == tl->l);
259
260 if ((*p == '\n') || start) {
261 struct bfelem *tr;
262
263 if (llen && start && *p != '\n')
264 WR(p, llen + 1);
265 else if (llen) {
266 WR(p + 1, llen);
267 if (start && *p == '\n')
268 WR(p, 1);
269 }
270 tr = TAILQ_NEXT(tl, entries);
271 llen = 0;
272 if (tr != NULL) {
273 TAILQ_FOREACH_FROM_SAFE(tr, &head,
274 entries, temp) {
275 if (tr->len)
276 WR(&tr->l, tr->len);
277 TAILQ_REMOVE(&head, tr,
278 entries);
279 free(tr);
280 }
281 }
282 }
283 }
284 tl->len = llen;
285 tl = TAILQ_PREV(tl, bfhead, entries);
286 }
287 TAILQ_REMOVE(&head, first, entries);
288 free(first);
289 }
290