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 <stdint.h> 54 #include <stdio.h> 55 #include <stdlib.h> 56 #include <string.h> 57 #include <unistd.h> 58 59 #include "extern.h" 60 61 static void r_buf(FILE *); 62 static void r_reg(FILE *, 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, 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, style, off, sbp); 90 else 91 switch(style) { 92 case FBYTES: 93 case RBYTES: 94 bytes(fp, off); 95 break; 96 case FLINES: 97 case RLINES: 98 lines(fp, off); 99 break; 100 case REVERSE: 101 r_buf(fp); 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, 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); 124 125 /* 126 * Last char is special, ignore whether newline or not. Note that 127 * size == 0 is dealt with above, and size == 1 sets curoff to -1. 128 */ 129 curoff = size - 2; 130 lineend = size; 131 while (curoff >= 0) { 132 if (curoff < map.mapoff || 133 curoff >= map.mapoff + (off_t)map.maplen) { 134 if (maparound(&map, curoff) != 0) { 135 ierr(); 136 return; 137 } 138 } 139 for (i = curoff - map.mapoff; i >= 0; i--) { 140 if (style == RBYTES && --off == 0) 141 break; 142 if (map.start[i] == '\n') 143 break; 144 } 145 /* `i' is either the map offset of a '\n', or -1. */ 146 curoff = map.mapoff + i; 147 if (i < 0) 148 continue; 149 150 /* Print the line and update offsets. */ 151 if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) { 152 ierr(); 153 return; 154 } 155 lineend = curoff + 1; 156 curoff--; 157 158 if (style == RLINES) 159 off--; 160 161 if (off == 0 && style != REVERSE) { 162 /* Avoid printing anything below. */ 163 curoff = 0; 164 break; 165 } 166 } 167 if (curoff < 0 && mapprint(&map, 0, lineend) != 0) { 168 ierr(); 169 return; 170 } 171 if (map.start != NULL && munmap(map.start, map.maplen)) 172 ierr(); 173 } 174 175 typedef struct bf { 176 struct bf *next; 177 struct bf *prev; 178 int len; 179 char *l; 180 } BF; 181 182 /* 183 * r_buf -- display a non-regular file in reverse order by line. 184 * 185 * This is the function that saves the entire input, storing the data in a 186 * doubly linked list of buffers and then displays them in reverse order. 187 * It has the usual nastiness of trying to find the newlines, as there's no 188 * guarantee that a newline occurs anywhere in the file, let alone in any 189 * particular buffer. If we run out of memory, input is discarded (and the 190 * user warned). 191 */ 192 static void 193 r_buf(FILE *fp) 194 { 195 BF *mark, *tl, *tr; 196 int ch, len, llen; 197 char *p; 198 off_t enomem; 199 200 #define BSZ (128 * 1024) 201 for (mark = NULL, enomem = 0;;) { 202 /* 203 * Allocate a new block and link it into place in a doubly 204 * linked list. If out of memory, toss the LRU block and 205 * keep going. 206 */ 207 if (enomem || (tl = malloc(sizeof(BF))) == NULL || 208 (tl->l = malloc(BSZ)) == NULL) { 209 if (!mark) 210 err(1, "malloc"); 211 tl = enomem ? tl->next : mark; 212 enomem += tl->len; 213 } else if (mark) { 214 tl->next = mark; 215 tl->prev = mark->prev; 216 mark->prev->next = tl; 217 mark->prev = tl; 218 } else { 219 mark = tl; 220 mark->next = mark->prev = mark; 221 } 222 223 /* Fill the block with input data. */ 224 for (p = tl->l, len = 0; 225 len < BSZ && (ch = getc(fp)) != EOF; ++len) 226 *p++ = ch; 227 228 if (ferror(fp)) { 229 ierr(); 230 return; 231 } 232 233 /* 234 * If no input data for this block and we tossed some data, 235 * recover it. 236 */ 237 if (!len && enomem) { 238 enomem -= tl->len; 239 tl = tl->prev; 240 break; 241 } 242 243 tl->len = len; 244 if (ch == EOF) 245 break; 246 } 247 248 if (enomem) { 249 warnx("warning: %jd bytes discarded", (intmax_t)enomem); 250 rval = 1; 251 } 252 253 /* 254 * Step through the blocks in the reverse order read. The last char 255 * is special, ignore whether newline or not. 256 */ 257 for (mark = tl;;) { 258 for (p = tl->l + (len = tl->len) - 1, llen = 0; len--; 259 --p, ++llen) 260 if (*p == '\n') { 261 if (llen) { 262 WR(p + 1, llen); 263 llen = 0; 264 } 265 if (tl == mark) 266 continue; 267 for (tr = tl->next; tr->len; tr = tr->next) { 268 WR(tr->l, tr->len); 269 tr->len = 0; 270 if (tr == mark) 271 break; 272 } 273 } 274 tl->len = llen; 275 if ((tl = tl->prev) == mark) 276 break; 277 } 278 tl = tl->next; 279 if (tl->len) { 280 WR(tl->l, tl->len); 281 tl->len = 0; 282 } 283 while ((tl = tl->next)->len) { 284 WR(tl->l, tl->len); 285 tl->len = 0; 286 } 287 } 288