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 #ifndef lint 38 #if 0 39 static char sccsid[] = "@(#)reverse.c 8.1 (Berkeley) 6/6/93"; 40 #endif 41 static const char rcsid[] = 42 "$FreeBSD$"; 43 #endif /* not lint */ 44 45 #include <sys/param.h> 46 #include <sys/stat.h> 47 #include <sys/mman.h> 48 49 #include <limits.h> 50 #include <errno.h> 51 #include <unistd.h> 52 #include <stdio.h> 53 #include <stdlib.h> 54 #include <string.h> 55 #include <err.h> 56 #include "extern.h" 57 58 static void r_buf __P((FILE *)); 59 static void r_reg __P((FILE *, enum STYLE, off_t, struct stat *)); 60 61 /* 62 * reverse -- display input in reverse order by line. 63 * 64 * There are six separate cases for this -- regular and non-regular 65 * files by bytes, lines or the whole file. 66 * 67 * BYTES display N bytes 68 * REG mmap the file and display the lines 69 * NOREG cyclically read characters into a wrap-around buffer 70 * 71 * LINES display N lines 72 * REG mmap the file and display the lines 73 * NOREG cyclically read lines into a wrap-around array of buffers 74 * 75 * FILE display the entire file 76 * REG mmap the file and display the lines 77 * NOREG cyclically read input into a linked list of buffers 78 */ 79 void 80 reverse(fp, style, off, sbp) 81 FILE *fp; 82 enum STYLE style; 83 off_t off; 84 struct stat *sbp; 85 { 86 if (style != REVERSE && off == 0) 87 return; 88 89 if (S_ISREG(sbp->st_mode)) 90 r_reg(fp, style, off, sbp); 91 else 92 switch(style) { 93 case FBYTES: 94 case RBYTES: 95 bytes(fp, off); 96 break; 97 case FLINES: 98 case RLINES: 99 lines(fp, off); 100 break; 101 case REVERSE: 102 r_buf(fp); 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(fp, style, off, sbp) 112 FILE *fp; 113 enum STYLE style; 114 off_t off; 115 struct stat *sbp; 116 { 117 struct mapinfo map; 118 off_t curoff, size, lineend; 119 int i; 120 121 if (!(size = sbp->st_size)) 122 return; 123 124 map.start = NULL; 125 map.mapoff = map.maxoff = size; 126 map.fd = fileno(fp); 127 128 /* 129 * Last char is special, ignore whether newline or not. Note that 130 * size == 0 is dealt with above, and size == 1 sets curoff to -1. 131 */ 132 curoff = size - 2; 133 lineend = size; 134 while (curoff >= 0) { 135 if (curoff < map.mapoff || curoff >= map.mapoff + map.maplen) { 136 if (maparound(&map, curoff) != 0) { 137 ierr(); 138 return; 139 } 140 } 141 for (i = curoff - map.mapoff; i >= 0; i--) { 142 if (style == RBYTES && --off == 0) 143 break; 144 if (map.start[i] == '\n') 145 break; 146 } 147 /* `i' is either the map offset of a '\n', or -1. */ 148 curoff = map.mapoff + i; 149 if (i < 0) 150 continue; 151 152 /* Print the line and update offsets. */ 153 if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) { 154 ierr(); 155 return; 156 } 157 lineend = curoff + 1; 158 curoff--; 159 160 if (style == RLINES) 161 off--; 162 163 if (off == 0 && style != REVERSE) { 164 /* Avoid printing anything below. */ 165 curoff = 0; 166 break; 167 } 168 } 169 if (curoff < 0 && mapprint(&map, 0, lineend) != 0) { 170 ierr(); 171 return; 172 } 173 if (map.start != NULL && munmap(map.start, map.maplen)) 174 ierr(); 175 } 176 177 typedef struct bf { 178 struct bf *next; 179 struct bf *prev; 180 int len; 181 char *l; 182 } BF; 183 184 /* 185 * r_buf -- display a non-regular file in reverse order by line. 186 * 187 * This is the function that saves the entire input, storing the data in a 188 * doubly linked list of buffers and then displays them in reverse order. 189 * It has the usual nastiness of trying to find the newlines, as there's no 190 * guarantee that a newline occurs anywhere in the file, let alone in any 191 * particular buffer. If we run out of memory, input is discarded (and the 192 * user warned). 193 */ 194 static void 195 r_buf(fp) 196 FILE *fp; 197 { 198 BF *mark, *tl, *tr; 199 int ch, len, llen; 200 char *p; 201 off_t enomem; 202 203 #define BSZ (128 * 1024) 204 for (mark = NULL, enomem = 0;;) { 205 /* 206 * Allocate a new block and link it into place in a doubly 207 * linked list. If out of memory, toss the LRU block and 208 * keep going. 209 */ 210 if (enomem || (tl = malloc(sizeof(BF))) == NULL || 211 (tl->l = malloc(BSZ)) == NULL) { 212 if (!mark) 213 err(1, "malloc"); 214 tl = enomem ? tl->next : mark; 215 enomem += tl->len; 216 } else if (mark) { 217 tl->next = mark; 218 tl->prev = mark->prev; 219 mark->prev->next = tl; 220 mark->prev = tl; 221 } else 222 mark->next = mark->prev = (mark = tl); 223 224 /* Fill the block with input data. */ 225 for (p = tl->l, len = 0; 226 len < BSZ && (ch = getc(fp)) != EOF; ++len) 227 *p++ = ch; 228 229 if (ferror(fp)) { 230 ierr(); 231 return; 232 } 233 234 /* 235 * If no input data for this block and we tossed some data, 236 * recover it. 237 */ 238 if (!len) { 239 if (enomem) 240 enomem -= tl->len; 241 tl = tl->prev; 242 break; 243 } 244 245 tl->len = len; 246 if (ch == EOF) 247 break; 248 } 249 250 if (enomem) { 251 warnx("warning: %qd bytes discarded", enomem); 252 rval = 1; 253 } 254 255 /* 256 * Step through the blocks in the reverse order read. The last char 257 * is special, ignore whether newline or not. 258 */ 259 for (mark = tl;;) { 260 for (p = tl->l + (len = tl->len) - 1, llen = 0; len--; 261 --p, ++llen) 262 if (*p == '\n') { 263 if (llen) { 264 WR(p + 1, llen); 265 llen = 0; 266 } 267 if (tl == mark) 268 continue; 269 for (tr = tl->next; tr->len; tr = tr->next) { 270 WR(tr->l, tr->len); 271 tr->len = 0; 272 if (tr == mark) 273 break; 274 } 275 } 276 tl->len = llen; 277 if ((tl = tl->prev) == mark) 278 break; 279 } 280 tl = tl->next; 281 if (tl->len) { 282 WR(tl->l, tl->len); 283 tl->len = 0; 284 } 285 while ((tl = tl->next)->len) { 286 WR(tl->l, tl->len); 287 tl->len = 0; 288 } 289 } 290