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 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 */ 36 37 #if 0 38 #ifndef lint 39 static char sccsid[] = "@(#)reverse.c 8.1 (Berkeley) 6/6/93"; 40 #endif /* not lint */ 41 #endif 42 43 #include <sys/cdefs.h> 44 __FBSDID("$FreeBSD$"); 45 46 #include <sys/param.h> 47 #include <sys/stat.h> 48 #include <sys/mman.h> 49 50 #include <err.h> 51 #include <errno.h> 52 #include <limits.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 *); 61 static void r_reg(FILE *, 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, 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, style, off, sbp); 89 else 90 switch(style) { 91 case FBYTES: 92 case RBYTES: 93 bytes(fp, off); 94 break; 95 case FLINES: 96 case RLINES: 97 lines(fp, off); 98 break; 99 case REVERSE: 100 r_buf(fp); 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, 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); 123 124 /* 125 * Last char is special, ignore whether newline or not. Note that 126 * size == 0 is dealt with above, and size == 1 sets curoff to -1. 127 */ 128 curoff = size - 2; 129 lineend = size; 130 while (curoff >= 0) { 131 if (curoff < map.mapoff || curoff >= map.mapoff + map.maplen) { 132 if (maparound(&map, curoff) != 0) { 133 ierr(); 134 return; 135 } 136 } 137 for (i = curoff - map.mapoff; i >= 0; i--) { 138 if (style == RBYTES && --off == 0) 139 break; 140 if (map.start[i] == '\n') 141 break; 142 } 143 /* `i' is either the map offset of a '\n', or -1. */ 144 curoff = map.mapoff + i; 145 if (i < 0) 146 continue; 147 148 /* Print the line and update offsets. */ 149 if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) { 150 ierr(); 151 return; 152 } 153 lineend = curoff + 1; 154 curoff--; 155 156 if (style == RLINES) 157 off--; 158 159 if (off == 0 && style != REVERSE) { 160 /* Avoid printing anything below. */ 161 curoff = 0; 162 break; 163 } 164 } 165 if (curoff < 0 && mapprint(&map, 0, lineend) != 0) { 166 ierr(); 167 return; 168 } 169 if (map.start != NULL && munmap(map.start, map.maplen)) 170 ierr(); 171 } 172 173 typedef struct bf { 174 struct bf *next; 175 struct bf *prev; 176 int len; 177 char *l; 178 } BF; 179 180 /* 181 * r_buf -- display a non-regular file in reverse order by line. 182 * 183 * This is the function that saves the entire input, storing the data in a 184 * doubly linked list of buffers and then displays them in reverse order. 185 * It has the usual nastiness of trying to find the newlines, as there's no 186 * guarantee that a newline occurs anywhere in the file, let alone in any 187 * particular buffer. If we run out of memory, input is discarded (and the 188 * user warned). 189 */ 190 static void 191 r_buf(FILE *fp) 192 { 193 BF *mark, *tl, *tr; 194 int ch, len, llen; 195 char *p; 196 off_t enomem; 197 198 #define BSZ (128 * 1024) 199 for (mark = NULL, enomem = 0;;) { 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 if (enomem || (tl = malloc(sizeof(BF))) == NULL || 206 (tl->l = malloc(BSZ)) == NULL) { 207 if (!mark) 208 err(1, "malloc"); 209 tl = enomem ? tl->next : mark; 210 enomem += tl->len; 211 } else if (mark) { 212 tl->next = mark; 213 tl->prev = mark->prev; 214 mark->prev->next = tl; 215 mark->prev = tl; 216 } else { 217 mark = tl; 218 mark->next = mark->prev = mark; 219 } 220 221 /* Fill the block with input data. */ 222 for (p = tl->l, len = 0; 223 len < BSZ && (ch = getc(fp)) != EOF; ++len) 224 *p++ = ch; 225 226 if (ferror(fp)) { 227 ierr(); 228 return; 229 } 230 231 /* 232 * If no input data for this block and we tossed some data, 233 * recover it. 234 */ 235 if (!len) { 236 if (enomem) 237 enomem -= tl->len; 238 tl = tl->prev; 239 break; 240 } 241 242 tl->len = len; 243 if (ch == EOF) 244 break; 245 } 246 247 if (enomem) { 248 warnx("warning: %qd bytes discarded", enomem); 249 rval = 1; 250 } 251 252 /* 253 * Step through the blocks in the reverse order read. The last char 254 * is special, ignore whether newline or not. 255 */ 256 for (mark = tl;;) { 257 for (p = tl->l + (len = tl->len) - 1, llen = 0; len--; 258 --p, ++llen) 259 if (*p == '\n') { 260 if (llen) { 261 WR(p + 1, llen); 262 llen = 0; 263 } 264 if (tl == mark) 265 continue; 266 for (tr = tl->next; tr->len; tr = tr->next) { 267 WR(tr->l, tr->len); 268 tr->len = 0; 269 if (tr == mark) 270 break; 271 } 272 } 273 tl->len = llen; 274 if ((tl = tl->prev) == mark) 275 break; 276 } 277 tl = tl->next; 278 if (tl->len) { 279 WR(tl->l, tl->len); 280 tl->len = 0; 281 } 282 while ((tl = tl->next)->len) { 283 WR(tl->l, tl->len); 284 tl->len = 0; 285 } 286 } 287