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 #include <sys/param.h>
36 #include <sys/queue.h>
37 #include <sys/stat.h>
38 #include <sys/mman.h>
39
40 #include <err.h>
41 #include <errno.h>
42 #include <limits.h>
43 #include <stdint.h>
44 #include <stdio.h>
45 #include <stdlib.h>
46 #include <string.h>
47 #include <unistd.h>
48
49 #include <libcasper.h>
50 #include <casper/cap_fileargs.h>
51
52 #include "extern.h"
53
54 static void r_buf(FILE *, const char *);
55 static void r_reg(FILE *, const char *, enum STYLE, off_t, struct stat *);
56
57 /*
58 * reverse -- display input in reverse order by line.
59 *
60 * There are six separate cases for this -- regular and non-regular
61 * files by bytes, lines or the whole file.
62 *
63 * BYTES display N bytes
64 * REG mmap the file and display the lines
65 * NOREG cyclically read characters into a wrap-around buffer
66 *
67 * LINES display N lines
68 * REG mmap the file and display the lines
69 * NOREG cyclically read lines into a wrap-around array of buffers
70 *
71 * FILE display the entire file
72 * REG mmap the file and display the lines
73 * NOREG cyclically read input into a linked list of buffers
74 */
75 void
reverse(FILE * fp,const char * fn,enum STYLE style,off_t off,struct stat * sbp)76 reverse(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
77 {
78 if (style != REVERSE && off == 0)
79 return;
80
81 if (S_ISREG(sbp->st_mode))
82 r_reg(fp, fn, style, off, sbp);
83 else
84 switch(style) {
85 case FBYTES:
86 case RBYTES:
87 bytes(fp, fn, off);
88 break;
89 case FLINES:
90 case RLINES:
91 lines(fp, fn, off);
92 break;
93 case REVERSE:
94 r_buf(fp, fn);
95 break;
96 default:
97 break;
98 }
99 }
100
101 /*
102 * r_reg -- display a regular file in reverse order by line.
103 */
104 static void
r_reg(FILE * fp,const char * fn,enum STYLE style,off_t off,struct stat * sbp)105 r_reg(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
106 {
107 struct mapinfo map;
108 off_t curoff, size, lineend;
109 int i;
110
111 if (!(size = sbp->st_size))
112 return;
113
114 map.start = NULL;
115 map.mapoff = map.maxoff = size;
116 map.fd = fileno(fp);
117 map.maplen = 0;
118
119 /*
120 * Last char is special, ignore whether newline or not. Note that
121 * size == 0 is dealt with above, and size == 1 sets curoff to -1.
122 */
123 curoff = size - 2;
124 lineend = size;
125 while (curoff >= 0) {
126 if (curoff < map.mapoff ||
127 curoff >= map.mapoff + (off_t)map.maplen) {
128 if (maparound(&map, curoff) != 0) {
129 ierr(fn);
130 return;
131 }
132 }
133 for (i = curoff - map.mapoff; i >= 0; i--) {
134 if (style == RBYTES && --off == 0)
135 break;
136 if (map.start[i] == '\n')
137 break;
138 }
139 /* `i' is either the map offset of a '\n', or -1. */
140 curoff = map.mapoff + i;
141 if (i < 0)
142 continue;
143
144 /* Print the line and update offsets. */
145 if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) {
146 ierr(fn);
147 return;
148 }
149 lineend = curoff + 1;
150 curoff--;
151
152 if (style == RLINES)
153 off--;
154
155 if (off == 0 && style != REVERSE) {
156 /* Avoid printing anything below. */
157 curoff = 0;
158 break;
159 }
160 }
161 if (curoff < 0 && mapprint(&map, 0, lineend) != 0) {
162 ierr(fn);
163 return;
164 }
165 if (map.start != NULL && munmap(map.start, map.maplen))
166 ierr(fn);
167 }
168
169 #define BSZ (128 * 1024)
170 typedef struct bfelem {
171 TAILQ_ENTRY(bfelem) entries;
172 size_t len;
173 char l[BSZ];
174 } bfelem_t;
175
176 /*
177 * r_buf -- display a non-regular file in reverse order by line.
178 *
179 * This is the function that saves the entire input, storing the data in a
180 * doubly linked list of buffers and then displays them in reverse order.
181 * It has the usual nastiness of trying to find the newlines, as there's no
182 * guarantee that a newline occurs anywhere in the file, let alone in any
183 * particular buffer. If we run out of memory, input is discarded (and the
184 * user warned).
185 */
186 static void
r_buf(FILE * fp,const char * fn)187 r_buf(FILE *fp, const char *fn)
188 {
189 struct bfelem *tl, *first = NULL;
190 size_t llen;
191 char *p;
192 off_t enomem = 0;
193 TAILQ_HEAD(bfhead, bfelem) head;
194
195 TAILQ_INIT(&head);
196
197 while (!feof(fp)) {
198 size_t len;
199
200 /*
201 * Allocate a new block and link it into place in a doubly
202 * linked list. If out of memory, toss the LRU block and
203 * keep going.
204 */
205 while ((tl = malloc(sizeof(bfelem_t))) == NULL) {
206 first = TAILQ_FIRST(&head);
207 if (TAILQ_EMPTY(&head))
208 err(1, "failed to allocate memory");
209 enomem += first->len;
210 TAILQ_REMOVE(&head, first, entries);
211 free(first);
212 }
213 TAILQ_INSERT_TAIL(&head, tl, entries);
214
215 /* Fill the block with input data. */
216 len = 0;
217 while ((!feof(fp)) && len < BSZ) {
218 p = tl->l + len;
219 len += fread(p, 1, BSZ - len, fp);
220 if (ferror(fp)) {
221 ierr(fn);
222 return;
223 }
224 }
225
226 tl->len = len;
227 }
228
229 if (enomem) {
230 warnx("warning: %jd bytes discarded", (intmax_t)enomem);
231 rval = 1;
232 }
233
234 /*
235 * Now print the lines in reverse order
236 * Outline:
237 * Scan backward for "\n",
238 * print forward to the end of the buffers
239 * free any buffers that start after the "\n" just found
240 * Loop
241 */
242 tl = TAILQ_LAST(&head, bfhead);
243 first = TAILQ_FIRST(&head);
244 while (tl != NULL) {
245 struct bfelem *temp;
246
247 for (p = tl->l + tl->len - 1, llen = 0; p >= tl->l;
248 --p, ++llen) {
249 int start = (tl == first && p == tl->l);
250
251 if ((*p == '\n') || start) {
252 struct bfelem *tr;
253
254 if (llen && start && *p != '\n')
255 WR(p, llen + 1);
256 else if (llen) {
257 WR(p + 1, llen);
258 if (start && *p == '\n')
259 WR(p, 1);
260 }
261 tr = TAILQ_NEXT(tl, entries);
262 llen = 0;
263 if (tr != NULL) {
264 TAILQ_FOREACH_FROM_SAFE(tr, &head,
265 entries, temp) {
266 if (tr->len)
267 WR(&tr->l, tr->len);
268 TAILQ_REMOVE(&head, tr,
269 entries);
270 free(tr);
271 }
272 }
273 }
274 }
275 tl->len = llen;
276 tl = TAILQ_PREV(tl, bfhead, entries);
277 }
278 TAILQ_REMOVE(&head, first, entries);
279 free(first);
280 }
281