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 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 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 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