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 #include <sys/param.h> 43 #include <sys/queue.h> 44 #include <sys/stat.h> 45 #include <sys/mman.h> 46 47 #include <err.h> 48 #include <errno.h> 49 #include <limits.h> 50 #include <stdint.h> 51 #include <stdio.h> 52 #include <stdlib.h> 53 #include <string.h> 54 #include <unistd.h> 55 56 #include <libcasper.h> 57 #include <casper/cap_fileargs.h> 58 59 #include "extern.h" 60 61 static void r_buf(FILE *, const char *); 62 static void r_reg(FILE *, const char *, enum STYLE, off_t, struct stat *); 63 64 /* 65 * reverse -- display input in reverse order by line. 66 * 67 * There are six separate cases for this -- regular and non-regular 68 * files by bytes, lines or the whole file. 69 * 70 * BYTES display N bytes 71 * REG mmap the file and display the lines 72 * NOREG cyclically read characters into a wrap-around buffer 73 * 74 * LINES display N lines 75 * REG mmap the file and display the lines 76 * NOREG cyclically read lines into a wrap-around array of buffers 77 * 78 * FILE display the entire file 79 * REG mmap the file and display the lines 80 * NOREG cyclically read input into a linked list of buffers 81 */ 82 void 83 reverse(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp) 84 { 85 if (style != REVERSE && off == 0) 86 return; 87 88 if (S_ISREG(sbp->st_mode)) 89 r_reg(fp, fn, style, off, sbp); 90 else 91 switch(style) { 92 case FBYTES: 93 case RBYTES: 94 bytes(fp, fn, off); 95 break; 96 case FLINES: 97 case RLINES: 98 lines(fp, fn, off); 99 break; 100 case REVERSE: 101 r_buf(fp, fn); 102 break; 103 default: 104 break; 105 } 106 } 107 108 /* 109 * r_reg -- display a regular file in reverse order by line. 110 */ 111 static void 112 r_reg(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp) 113 { 114 struct mapinfo map; 115 off_t curoff, size, lineend; 116 int i; 117 118 if (!(size = sbp->st_size)) 119 return; 120 121 map.start = NULL; 122 map.mapoff = map.maxoff = size; 123 map.fd = fileno(fp); 124 map.maplen = 0; 125 126 /* 127 * Last char is special, ignore whether newline or not. Note that 128 * size == 0 is dealt with above, and size == 1 sets curoff to -1. 129 */ 130 curoff = size - 2; 131 lineend = size; 132 while (curoff >= 0) { 133 if (curoff < map.mapoff || 134 curoff >= map.mapoff + (off_t)map.maplen) { 135 if (maparound(&map, curoff) != 0) { 136 ierr(fn); 137 return; 138 } 139 } 140 for (i = curoff - map.mapoff; i >= 0; i--) { 141 if (style == RBYTES && --off == 0) 142 break; 143 if (map.start[i] == '\n') 144 break; 145 } 146 /* `i' is either the map offset of a '\n', or -1. */ 147 curoff = map.mapoff + i; 148 if (i < 0) 149 continue; 150 151 /* Print the line and update offsets. */ 152 if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) { 153 ierr(fn); 154 return; 155 } 156 lineend = curoff + 1; 157 curoff--; 158 159 if (style == RLINES) 160 off--; 161 162 if (off == 0 && style != REVERSE) { 163 /* Avoid printing anything below. */ 164 curoff = 0; 165 break; 166 } 167 } 168 if (curoff < 0 && mapprint(&map, 0, lineend) != 0) { 169 ierr(fn); 170 return; 171 } 172 if (map.start != NULL && munmap(map.start, map.maplen)) 173 ierr(fn); 174 } 175 176 #define BSZ (128 * 1024) 177 typedef struct bfelem { 178 TAILQ_ENTRY(bfelem) entries; 179 size_t len; 180 char l[BSZ]; 181 } bfelem_t; 182 183 /* 184 * r_buf -- display a non-regular file in reverse order by line. 185 * 186 * This is the function that saves the entire input, storing the data in a 187 * doubly linked list of buffers and then displays them in reverse order. 188 * It has the usual nastiness of trying to find the newlines, as there's no 189 * guarantee that a newline occurs anywhere in the file, let alone in any 190 * particular buffer. If we run out of memory, input is discarded (and the 191 * user warned). 192 */ 193 static void 194 r_buf(FILE *fp, const char *fn) 195 { 196 struct bfelem *tl, *first = NULL; 197 size_t llen; 198 char *p; 199 off_t enomem = 0; 200 TAILQ_HEAD(bfhead, bfelem) head; 201 202 TAILQ_INIT(&head); 203 204 while (!feof(fp)) { 205 size_t len; 206 207 /* 208 * Allocate a new block and link it into place in a doubly 209 * linked list. If out of memory, toss the LRU block and 210 * keep going. 211 */ 212 while ((tl = malloc(sizeof(bfelem_t))) == NULL) { 213 first = TAILQ_FIRST(&head); 214 if (TAILQ_EMPTY(&head)) 215 err(1, "malloc"); 216 enomem += first->len; 217 TAILQ_REMOVE(&head, first, entries); 218 free(first); 219 } 220 TAILQ_INSERT_TAIL(&head, tl, entries); 221 222 /* Fill the block with input data. */ 223 len = 0; 224 while ((!feof(fp)) && len < BSZ) { 225 p = tl->l + len; 226 len += fread(p, 1, BSZ - len, fp); 227 if (ferror(fp)) { 228 ierr(fn); 229 return; 230 } 231 } 232 233 tl->len = len; 234 } 235 236 if (enomem) { 237 warnx("warning: %jd bytes discarded", (intmax_t)enomem); 238 rval = 1; 239 } 240 241 /* 242 * Now print the lines in reverse order 243 * Outline: 244 * Scan backward for "\n", 245 * print forward to the end of the buffers 246 * free any buffers that start after the "\n" just found 247 * Loop 248 */ 249 tl = TAILQ_LAST(&head, bfhead); 250 first = TAILQ_FIRST(&head); 251 while (tl != NULL) { 252 struct bfelem *temp; 253 254 for (p = tl->l + tl->len - 1, llen = 0; p >= tl->l; 255 --p, ++llen) { 256 int start = (tl == first && p == tl->l); 257 258 if ((*p == '\n') || start) { 259 struct bfelem *tr; 260 261 if (llen && start && *p != '\n') 262 WR(p, llen + 1); 263 else if (llen) { 264 WR(p + 1, llen); 265 if (start && *p == '\n') 266 WR(p, 1); 267 } 268 tr = TAILQ_NEXT(tl, entries); 269 llen = 0; 270 if (tr != NULL) { 271 TAILQ_FOREACH_FROM_SAFE(tr, &head, 272 entries, temp) { 273 if (tr->len) 274 WR(&tr->l, tr->len); 275 TAILQ_REMOVE(&head, tr, 276 entries); 277 free(tr); 278 } 279 } 280 } 281 } 282 tl->len = llen; 283 tl = TAILQ_PREV(tl, bfhead, entries); 284 } 285 TAILQ_REMOVE(&head, first, entries); 286 free(first); 287 } 288