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 "extern.h" 59 60 static void r_buf(FILE *, const char *); 61 static void r_reg(FILE *, const char *, enum STYLE, off_t, struct stat *); 62 63 /* 64 * reverse -- display input in reverse order by line. 65 * 66 * There are six separate cases for this -- regular and non-regular 67 * files by bytes, lines or the whole file. 68 * 69 * BYTES display N bytes 70 * REG mmap the file and display the lines 71 * NOREG cyclically read characters into a wrap-around buffer 72 * 73 * LINES display N lines 74 * REG mmap the file and display the lines 75 * NOREG cyclically read lines into a wrap-around array of buffers 76 * 77 * FILE display the entire file 78 * REG mmap the file and display the lines 79 * NOREG cyclically read input into a linked list of buffers 80 */ 81 void 82 reverse(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp) 83 { 84 if (style != REVERSE && off == 0) 85 return; 86 87 if (S_ISREG(sbp->st_mode)) 88 r_reg(fp, fn, style, off, sbp); 89 else 90 switch(style) { 91 case FBYTES: 92 case RBYTES: 93 bytes(fp, fn, off); 94 break; 95 case FLINES: 96 case RLINES: 97 lines(fp, fn, off); 98 break; 99 case REVERSE: 100 r_buf(fp, fn); 101 break; 102 default: 103 break; 104 } 105 } 106 107 /* 108 * r_reg -- display a regular file in reverse order by line. 109 */ 110 static void 111 r_reg(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp) 112 { 113 struct mapinfo map; 114 off_t curoff, size, lineend; 115 int i; 116 117 if (!(size = sbp->st_size)) 118 return; 119 120 map.start = NULL; 121 map.mapoff = map.maxoff = size; 122 map.fd = fileno(fp); 123 map.maplen = 0; 124 125 /* 126 * Last char is special, ignore whether newline or not. Note that 127 * size == 0 is dealt with above, and size == 1 sets curoff to -1. 128 */ 129 curoff = size - 2; 130 lineend = size; 131 while (curoff >= 0) { 132 if (curoff < map.mapoff || 133 curoff >= map.mapoff + (off_t)map.maplen) { 134 if (maparound(&map, curoff) != 0) { 135 ierr(fn); 136 return; 137 } 138 } 139 for (i = curoff - map.mapoff; i >= 0; i--) { 140 if (style == RBYTES && --off == 0) 141 break; 142 if (map.start[i] == '\n') 143 break; 144 } 145 /* `i' is either the map offset of a '\n', or -1. */ 146 curoff = map.mapoff + i; 147 if (i < 0) 148 continue; 149 150 /* Print the line and update offsets. */ 151 if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) { 152 ierr(fn); 153 return; 154 } 155 lineend = curoff + 1; 156 curoff--; 157 158 if (style == RLINES) 159 off--; 160 161 if (off == 0 && style != REVERSE) { 162 /* Avoid printing anything below. */ 163 curoff = 0; 164 break; 165 } 166 } 167 if (curoff < 0 && mapprint(&map, 0, lineend) != 0) { 168 ierr(fn); 169 return; 170 } 171 if (map.start != NULL && munmap(map.start, map.maplen)) 172 ierr(fn); 173 } 174 175 #define BSZ (128 * 1024) 176 typedef struct bfelem { 177 TAILQ_ENTRY(bfelem) entries; 178 size_t len; 179 char l[BSZ]; 180 } bfelem_t; 181 182 /* 183 * r_buf -- display a non-regular file in reverse order by line. 184 * 185 * This is the function that saves the entire input, storing the data in a 186 * doubly linked list of buffers and then displays them in reverse order. 187 * It has the usual nastiness of trying to find the newlines, as there's no 188 * guarantee that a newline occurs anywhere in the file, let alone in any 189 * particular buffer. If we run out of memory, input is discarded (and the 190 * user warned). 191 */ 192 static void 193 r_buf(FILE *fp, const char *fn) 194 { 195 struct bfelem *tl, *first = NULL; 196 size_t llen; 197 char *p; 198 off_t enomem = 0; 199 TAILQ_HEAD(bfhead, bfelem) head; 200 201 TAILQ_INIT(&head); 202 203 while (!feof(fp)) { 204 size_t len; 205 206 /* 207 * Allocate a new block and link it into place in a doubly 208 * linked list. If out of memory, toss the LRU block and 209 * keep going. 210 */ 211 while ((tl = malloc(sizeof(bfelem_t))) == NULL) { 212 first = TAILQ_FIRST(&head); 213 if (TAILQ_EMPTY(&head)) 214 err(1, "malloc"); 215 enomem += first->len; 216 TAILQ_REMOVE(&head, first, entries); 217 free(first); 218 } 219 TAILQ_INSERT_TAIL(&head, tl, entries); 220 221 /* Fill the block with input data. */ 222 len = 0; 223 while ((!feof(fp)) && len < BSZ) { 224 p = tl->l + len; 225 len += fread(p, 1, BSZ - len, fp); 226 if (ferror(fp)) { 227 ierr(fn); 228 return; 229 } 230 } 231 232 tl->len = len; 233 } 234 235 if (enomem) { 236 warnx("warning: %jd bytes discarded", (intmax_t)enomem); 237 rval = 1; 238 } 239 240 /* 241 * Now print the lines in reverse order 242 * Outline: 243 * Scan backward for "\n", 244 * print forward to the end of the buffers 245 * free any buffers that start after the "\n" just found 246 * Loop 247 */ 248 tl = TAILQ_LAST(&head, bfhead); 249 first = TAILQ_FIRST(&head); 250 while (tl != NULL) { 251 struct bfelem *temp; 252 253 for (p = tl->l + tl->len - 1, llen = 0; p >= tl->l; 254 --p, ++llen) { 255 int start = (tl == first && p == tl->l); 256 257 if ((*p == '\n') || start) { 258 struct bfelem *tr; 259 260 if (llen && start && *p != '\n') 261 WR(p, llen + 1); 262 else if (llen) { 263 WR(p + 1, llen); 264 if (start && *p == '\n') 265 WR(p, 1); 266 } 267 tr = TAILQ_NEXT(tl, entries); 268 llen = 0; 269 if (tr != NULL) { 270 TAILQ_FOREACH_FROM_SAFE(tr, &head, 271 entries, temp) { 272 if (tr->len) 273 WR(&tr->l, tr->len); 274 TAILQ_REMOVE(&head, tr, 275 entries); 276 free(tr); 277 } 278 } 279 } 280 } 281 tl->len = llen; 282 tl = TAILQ_PREV(tl, bfhead, entries); 283 } 284 TAILQ_REMOVE(&head, first, entries); 285 free(first); 286 } 287