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 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 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 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