1 /*-
2 * Copyright (c) 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Edward Sze-Tyan Wang.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
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.
19 *
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
30 * SUCH DAMAGE.
31 */
32
33 #if 0
34 #ifndef lint
35 static char sccsid[] = "@(#)reverse.c 8.1 (Berkeley) 6/6/93";
36 #endif /* not lint */
37 #endif
38
39 #include <sys/cdefs.h>
40 __FBSDID("$FreeBSD$");
41
42 #include <sys/param.h>
43 #include <sys/stat.h>
44 #include <sys/mman.h>
45
46 #include <err.h>
47 #include <errno.h>
48 #include <limits.h>
49 #include <stdint.h>
50 #include <stdio.h>
51 #include <stdlib.h>
52 #include <string.h>
53 #include <unistd.h>
54
55 #include "extern.h"
56
57 static void r_buf(FILE *, const char *);
58 static void r_reg(FILE *, const char *, enum STYLE, off_t, struct stat *);
59
60 /*
61 * reverse -- display input in reverse order by line.
62 *
63 * There are six separate cases for this -- regular and non-regular
64 * files by bytes, lines or the whole file.
65 *
66 * BYTES display N bytes
67 * REG mmap the file and display the lines
68 * NOREG cyclically read characters into a wrap-around buffer
69 *
70 * LINES display N lines
71 * REG mmap the file and display the lines
72 * NOREG cyclically read lines into a wrap-around array of buffers
73 *
74 * FILE display the entire file
75 * REG mmap the file and display the lines
76 * NOREG cyclically read input into a linked list of buffers
77 */
78 void
reverse(FILE * fp,const char * fn,enum STYLE style,off_t off,struct stat * sbp)79 reverse(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
80 {
81 if (style != REVERSE && off == 0)
82 return;
83
84 if (S_ISREG(sbp->st_mode))
85 r_reg(fp, fn, style, off, sbp);
86 else
87 switch(style) {
88 case FBYTES:
89 case RBYTES:
90 bytes(fp, fn, off);
91 break;
92 case FLINES:
93 case RLINES:
94 lines(fp, fn, off);
95 break;
96 case REVERSE:
97 r_buf(fp, fn);
98 break;
99 default:
100 break;
101 }
102 }
103
104 /*
105 * r_reg -- display a regular file in reverse order by line.
106 */
107 static void
r_reg(FILE * fp,const char * fn,enum STYLE style,off_t off,struct stat * sbp)108 r_reg(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp)
109 {
110 struct mapinfo map;
111 off_t curoff, size, lineend;
112 int i;
113
114 if (!(size = sbp->st_size))
115 return;
116
117 map.start = NULL;
118 map.mapoff = map.maxoff = size;
119 map.fd = fileno(fp);
120
121 /*
122 * Last char is special, ignore whether newline or not. Note that
123 * size == 0 is dealt with above, and size == 1 sets curoff to -1.
124 */
125 curoff = size - 2;
126 lineend = size;
127 while (curoff >= 0) {
128 if (curoff < map.mapoff ||
129 curoff >= map.mapoff + (off_t)map.maplen) {
130 if (maparound(&map, curoff) != 0) {
131 ierr(fn);
132 return;
133 }
134 }
135 for (i = curoff - map.mapoff; i >= 0; i--) {
136 if (style == RBYTES && --off == 0)
137 break;
138 if (map.start[i] == '\n')
139 break;
140 }
141 /* `i' is either the map offset of a '\n', or -1. */
142 curoff = map.mapoff + i;
143 if (i < 0)
144 continue;
145
146 /* Print the line and update offsets. */
147 if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) {
148 ierr(fn);
149 return;
150 }
151 lineend = curoff + 1;
152 curoff--;
153
154 if (style == RLINES)
155 off--;
156
157 if (off == 0 && style != REVERSE) {
158 /* Avoid printing anything below. */
159 curoff = 0;
160 break;
161 }
162 }
163 if (curoff < 0 && mapprint(&map, 0, lineend) != 0) {
164 ierr(fn);
165 return;
166 }
167 if (map.start != NULL && munmap(map.start, map.maplen))
168 ierr(fn);
169 }
170
171 typedef struct bf {
172 struct bf *next;
173 struct bf *prev;
174 int len;
175 char *l;
176 } BF;
177
178 /*
179 * r_buf -- display a non-regular file in reverse order by line.
180 *
181 * This is the function that saves the entire input, storing the data in a
182 * doubly linked list of buffers and then displays them in reverse order.
183 * It has the usual nastiness of trying to find the newlines, as there's no
184 * guarantee that a newline occurs anywhere in the file, let alone in any
185 * particular buffer. If we run out of memory, input is discarded (and the
186 * user warned).
187 */
188 static void
r_buf(FILE * fp,const char * fn)189 r_buf(FILE *fp, const char *fn)
190 {
191 BF *mark, *tl, *tr;
192 int ch, len, llen;
193 char *p;
194 off_t enomem;
195
196 tl = NULL;
197 #define BSZ (128 * 1024)
198 for (mark = NULL, enomem = 0;;) {
199 /*
200 * Allocate a new block and link it into place in a doubly
201 * linked list. If out of memory, toss the LRU block and
202 * keep going.
203 */
204 if (enomem || (tl = malloc(sizeof(BF))) == NULL ||
205 (tl->l = malloc(BSZ)) == NULL) {
206 if (!mark)
207 err(1, "malloc");
208 tl = enomem ? tl->next : mark;
209 enomem += tl->len;
210 } else if (mark) {
211 tl->next = mark;
212 tl->prev = mark->prev;
213 mark->prev->next = tl;
214 mark->prev = tl;
215 } else {
216 mark = tl;
217 mark->next = mark->prev = mark;
218 }
219
220 /* Fill the block with input data. */
221 for (p = tl->l, len = 0;
222 len < BSZ && (ch = getc(fp)) != EOF; ++len)
223 *p++ = ch;
224
225 if (ferror(fp)) {
226 ierr(fn);
227 return;
228 }
229
230 /*
231 * If no input data for this block and we tossed some data,
232 * recover it.
233 */
234 if (!len && enomem) {
235 enomem -= tl->len;
236 tl = tl->prev;
237 break;
238 }
239
240 tl->len = len;
241 if (ch == EOF)
242 break;
243 }
244
245 if (enomem) {
246 warnx("warning: %jd bytes discarded", (intmax_t)enomem);
247 rval = 1;
248 }
249
250 /*
251 * Step through the blocks in the reverse order read. The last char
252 * is special, ignore whether newline or not.
253 */
254 for (mark = tl;;) {
255 for (p = tl->l + (len = tl->len) - 1, llen = 0; len--;
256 --p, ++llen)
257 if (*p == '\n') {
258 if (llen) {
259 WR(p + 1, llen);
260 llen = 0;
261 }
262 if (tl == mark)
263 continue;
264 for (tr = tl->next; tr->len; tr = tr->next) {
265 WR(tr->l, tr->len);
266 tr->len = 0;
267 if (tr == mark)
268 break;
269 }
270 }
271 tl->len = llen;
272 if ((tl = tl->prev) == mark)
273 break;
274 }
275 tl = tl->next;
276 if (tl->len) {
277 WR(tl->l, tl->len);
278 tl->len = 0;
279 }
280 while ((tl = tl->next)->len) {
281 WR(tl->l, tl->len);
282 tl->len = 0;
283 }
284 }
285