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 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 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 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