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(fp, style, off, sbp) 83 FILE *fp; 84 enum STYLE style; 85 off_t off; 86 struct stat *sbp; 87 { 88 if (style != REVERSE && off == 0) 89 return; 90 91 if (S_ISREG(sbp->st_mode)) 92 r_reg(fp, style, off, sbp); 93 else 94 switch(style) { 95 case FBYTES: 96 case RBYTES: 97 bytes(fp, off); 98 break; 99 case FLINES: 100 case RLINES: 101 lines(fp, off); 102 break; 103 case REVERSE: 104 r_buf(fp); 105 break; 106 default: 107 break; 108 } 109 } 110 111 /* 112 * r_reg -- display a regular file in reverse order by line. 113 */ 114 static void 115 r_reg(fp, style, off, sbp) 116 FILE *fp; 117 enum STYLE style; 118 off_t off; 119 struct stat *sbp; 120 { 121 struct mapinfo map; 122 off_t curoff, size, lineend; 123 int i; 124 125 if (!(size = sbp->st_size)) 126 return; 127 128 map.start = NULL; 129 map.mapoff = map.maxoff = size; 130 map.fd = fileno(fp); 131 132 /* 133 * Last char is special, ignore whether newline or not. Note that 134 * size == 0 is dealt with above, and size == 1 sets curoff to -1. 135 */ 136 curoff = size - 2; 137 lineend = size; 138 while (curoff >= 0) { 139 if (curoff < map.mapoff || curoff >= map.mapoff + map.maplen) { 140 if (maparound(&map, curoff) != 0) { 141 ierr(); 142 return; 143 } 144 } 145 for (i = curoff - map.mapoff; i >= 0; i--) { 146 if (style == RBYTES && --off == 0) 147 break; 148 if (map.start[i] == '\n') 149 break; 150 } 151 /* `i' is either the map offset of a '\n', or -1. */ 152 curoff = map.mapoff + i; 153 if (i < 0) 154 continue; 155 156 /* Print the line and update offsets. */ 157 if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) { 158 ierr(); 159 return; 160 } 161 lineend = curoff + 1; 162 curoff--; 163 164 if (style == RLINES) 165 off--; 166 167 if (off == 0 && style != REVERSE) { 168 /* Avoid printing anything below. */ 169 curoff = 0; 170 break; 171 } 172 } 173 if (curoff < 0 && mapprint(&map, 0, lineend) != 0) { 174 ierr(); 175 return; 176 } 177 if (map.start != NULL && munmap(map.start, map.maplen)) 178 ierr(); 179 } 180 181 typedef struct bf { 182 struct bf *next; 183 struct bf *prev; 184 int len; 185 char *l; 186 } BF; 187 188 /* 189 * r_buf -- display a non-regular file in reverse order by line. 190 * 191 * This is the function that saves the entire input, storing the data in a 192 * doubly linked list of buffers and then displays them in reverse order. 193 * It has the usual nastiness of trying to find the newlines, as there's no 194 * guarantee that a newline occurs anywhere in the file, let alone in any 195 * particular buffer. If we run out of memory, input is discarded (and the 196 * user warned). 197 */ 198 static void 199 r_buf(fp) 200 FILE *fp; 201 { 202 BF *mark, *tl, *tr; 203 int ch, len, llen; 204 char *p; 205 off_t enomem; 206 207 #define BSZ (128 * 1024) 208 for (mark = NULL, enomem = 0;;) { 209 /* 210 * Allocate a new block and link it into place in a doubly 211 * linked list. If out of memory, toss the LRU block and 212 * keep going. 213 */ 214 if (enomem || (tl = malloc(sizeof(BF))) == NULL || 215 (tl->l = malloc(BSZ)) == NULL) { 216 if (!mark) 217 err(1, "malloc"); 218 tl = enomem ? tl->next : mark; 219 enomem += tl->len; 220 } else if (mark) { 221 tl->next = mark; 222 tl->prev = mark->prev; 223 mark->prev->next = tl; 224 mark->prev = tl; 225 } else { 226 mark = tl; 227 mark->next = mark->prev = mark; 228 } 229 230 /* Fill the block with input data. */ 231 for (p = tl->l, len = 0; 232 len < BSZ && (ch = getc(fp)) != EOF; ++len) 233 *p++ = ch; 234 235 if (ferror(fp)) { 236 ierr(); 237 return; 238 } 239 240 /* 241 * If no input data for this block and we tossed some data, 242 * recover it. 243 */ 244 if (!len) { 245 if (enomem) 246 enomem -= tl->len; 247 tl = tl->prev; 248 break; 249 } 250 251 tl->len = len; 252 if (ch == EOF) 253 break; 254 } 255 256 if (enomem) { 257 warnx("warning: %qd bytes discarded", enomem); 258 rval = 1; 259 } 260 261 /* 262 * Step through the blocks in the reverse order read. The last char 263 * is special, ignore whether newline or not. 264 */ 265 for (mark = tl;;) { 266 for (p = tl->l + (len = tl->len) - 1, llen = 0; len--; 267 --p, ++llen) 268 if (*p == '\n') { 269 if (llen) { 270 WR(p + 1, llen); 271 llen = 0; 272 } 273 if (tl == mark) 274 continue; 275 for (tr = tl->next; tr->len; tr = tr->next) { 276 WR(tr->l, tr->len); 277 tr->len = 0; 278 if (tr == mark) 279 break; 280 } 281 } 282 tl->len = llen; 283 if ((tl = tl->prev) == mark) 284 break; 285 } 286 tl = tl->next; 287 if (tl->len) { 288 WR(tl->l, tl->len); 289 tl->len = 0; 290 } 291 while ((tl = tl->next)->len) { 292 WR(tl->l, tl->len); 293 tl->len = 0; 294 } 295 } 296