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 #include <sys/param.h> 34 #include <sys/stat.h> 35 #include <sys/mman.h> 36 37 #include <err.h> 38 #include <errno.h> 39 #include <limits.h> 40 #include <stdint.h> 41 #include <stdio.h> 42 #include <stdlib.h> 43 #include <string.h> 44 #include <unistd.h> 45 46 #include "extern.h" 47 48 static void r_buf(FILE *, const char *); 49 static void r_reg(FILE *, const char *, enum STYLE, off_t, struct stat *); 50 51 /* 52 * reverse -- display input in reverse order by line. 53 * 54 * There are six separate cases for this -- regular and non-regular 55 * files by bytes, lines or the whole file. 56 * 57 * BYTES display N bytes 58 * REG mmap the file and display the lines 59 * NOREG cyclically read characters into a wrap-around buffer 60 * 61 * LINES display N lines 62 * REG mmap the file and display the lines 63 * NOREG cyclically read lines into a wrap-around array of buffers 64 * 65 * FILE display the entire file 66 * REG mmap the file and display the lines 67 * NOREG cyclically read input into a linked list of buffers 68 */ 69 void 70 reverse(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp) 71 { 72 if (style != REVERSE && off == 0) 73 return; 74 75 if (S_ISREG(sbp->st_mode)) 76 r_reg(fp, fn, style, off, sbp); 77 else 78 switch (style) { 79 case FBYTES: 80 case RBYTES: 81 (void) bytes(fp, fn, off); 82 break; 83 case FLINES: 84 case RLINES: 85 (void) lines(fp, fn, off); 86 break; 87 case REVERSE: 88 r_buf(fp, fn); 89 break; 90 default: 91 break; 92 } 93 } 94 95 /* 96 * r_reg -- display a regular file in reverse order by line. 97 */ 98 static void 99 r_reg(FILE *fp, const char *fn, enum STYLE style, off_t off, struct stat *sbp) 100 { 101 struct mapinfo map; 102 off_t curoff, size, lineend; 103 int i; 104 105 if ((size = sbp->st_size) == 0) 106 return; 107 108 map.start = NULL; 109 map.mapoff = map.maxoff = size; 110 map.fd = fileno(fp); 111 112 /* 113 * Last char is special, ignore whether newline or not. Note that 114 * size == 0 is dealt with above, and size == 1 sets curoff to -1. 115 */ 116 curoff = size - 2; 117 lineend = size; 118 while (curoff >= 0) { 119 if (curoff < map.mapoff || 120 curoff >= map.mapoff + (off_t)map.maplen) { 121 if (maparound(&map, curoff) != 0) { 122 ierr(fn); 123 return; 124 } 125 } 126 for (i = curoff - map.mapoff; i >= 0; i--) { 127 if (style == RBYTES && --off == 0) 128 break; 129 if (map.start[i] == '\n') 130 break; 131 } 132 /* `i' is either the map offset of a '\n', or -1. */ 133 curoff = map.mapoff + i; 134 if (i < 0) 135 continue; 136 137 /* Print the line and update offsets. */ 138 if (mapprint(&map, curoff + 1, lineend - curoff - 1) != 0) { 139 ierr(fn); 140 return; 141 } 142 lineend = curoff + 1; 143 curoff--; 144 145 if (style == RLINES) 146 off--; 147 148 if (off == 0 && style != REVERSE) { 149 /* Avoid printing anything below. */ 150 curoff = 0; 151 break; 152 } 153 } 154 if (curoff < 0 && mapprint(&map, 0, lineend) != 0) { 155 ierr(fn); 156 return; 157 } 158 if (map.start != NULL && munmap(map.start, map.maplen)) 159 ierr(fn); 160 } 161 162 typedef struct bf { 163 struct bf *next; 164 struct bf *prev; 165 int len; 166 char *l; 167 } BF; 168 169 /* 170 * r_buf -- display a non-regular file in reverse order by line. 171 * 172 * This is the function that saves the entire input, storing the data in a 173 * doubly linked list of buffers and then displays them in reverse order. 174 * It has the usual nastiness of trying to find the newlines, as there's no 175 * guarantee that a newline occurs anywhere in the file, let alone in any 176 * particular buffer. If we run out of memory, input is discarded (and the 177 * user warned). 178 */ 179 static void 180 r_buf(FILE *fp, const char *fn) 181 { 182 BF *mark, *tl, *tr; 183 int ch, len, llen; 184 char *p; 185 off_t enomem; 186 187 tl = NULL; 188 #define BSZ (128 * 1024) 189 for (mark = NULL, enomem = 0; ; ) { 190 /* 191 * Allocate a new block and link it into place in a doubly 192 * linked list. If out of memory, toss the LRU block and 193 * keep going. 194 */ 195 if (enomem || (tl = malloc(sizeof (BF))) == NULL || 196 (tl->l = malloc(BSZ)) == NULL) { 197 if (!mark) 198 err(1, "malloc"); 199 tl = enomem ? tl->next : mark; 200 enomem += tl->len; 201 } else if (mark) { 202 tl->next = mark; 203 tl->prev = mark->prev; 204 mark->prev->next = tl; 205 mark->prev = tl; 206 } else { 207 mark = tl; 208 mark->next = mark->prev = mark; 209 } 210 211 /* Fill the block with input data. */ 212 for (p = tl->l, len = 0; 213 len < BSZ && (ch = getc(fp)) != EOF; ++len) 214 *p++ = ch; 215 216 if (ferror(fp)) { 217 ierr(fn); 218 return; 219 } 220 221 /* 222 * If no input data for this block and we tossed some data, 223 * recover it. 224 */ 225 if (!len && enomem) { 226 enomem -= tl->len; 227 tl = tl->prev; 228 break; 229 } 230 231 tl->len = len; 232 if (ch == EOF) 233 break; 234 } 235 236 if (enomem) { 237 warnx("warning: %jd bytes discarded", (intmax_t)enomem); 238 rval = 1; 239 } 240 241 /* 242 * Step through the blocks in the reverse order read. The last char 243 * is special, ignore whether newline or not. 244 */ 245 for (mark = tl; ; ) { 246 for (p = tl->l + (len = tl->len) - 1, llen = 0; len--; 247 --p, ++llen) 248 if (*p == '\n') { 249 if (llen) { 250 WR(p + 1, llen); 251 llen = 0; 252 } 253 if (tl == mark) 254 continue; 255 for (tr = tl->next; tr->len; tr = tr->next) { 256 WR(tr->l, tr->len); 257 tr->len = 0; 258 if (tr == mark) 259 break; 260 } 261 } 262 tl->len = llen; 263 if ((tl = tl->prev) == mark) 264 break; 265 } 266 tl = tl->next; 267 if (tl->len) { 268 WR(tl->l, tl->len); 269 tl->len = 0; 270 } 271 while ((tl = tl->next)->len) { 272 WR(tl->l, tl->len); 273 tl->len = 0; 274 } 275 } 276