read.c revision 225736
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/cdefs.h> 34 35__FBSDID("$FreeBSD: stable/9/usr.bin/tail/read.c 216370 2010-12-11 08:32:16Z joel $"); 36 37#ifndef lint 38static const char sccsid[] = "@(#)read.c 8.1 (Berkeley) 6/6/93"; 39#endif 40 41#include <sys/types.h> 42#include <sys/stat.h> 43 44#include <err.h> 45#include <errno.h> 46#include <fcntl.h> 47#include <stdio.h> 48#include <stdlib.h> 49#include <string.h> 50#include <unistd.h> 51 52#include "extern.h" 53 54/* 55 * bytes -- read bytes to an offset from the end and display. 56 * 57 * This is the function that reads to a byte offset from the end of the input, 58 * storing the data in a wrap-around buffer which is then displayed. If the 59 * rflag is set, the data is displayed in lines in reverse order, and this 60 * routine has the usual nastiness of trying to find the newlines. Otherwise, 61 * it is displayed from the character closest to the beginning of the input to 62 * the end. 63 */ 64int 65bytes(FILE *fp, const char *fn, off_t off) 66{ 67 int ch, len, tlen; 68 char *ep, *p, *t; 69 int wrap; 70 char *sp; 71 72 if ((sp = p = malloc(off)) == NULL) 73 err(1, "malloc"); 74 75 for (wrap = 0, ep = p + off; (ch = getc(fp)) != EOF;) { 76 *p = ch; 77 if (++p == ep) { 78 wrap = 1; 79 p = sp; 80 } 81 } 82 if (ferror(fp)) { 83 ierr(fn); 84 free(sp); 85 return 1; 86 } 87 88 if (rflag) { 89 for (t = p - 1, len = 0; t >= sp; --t, ++len) 90 if (*t == '\n' && len) { 91 WR(t + 1, len); 92 len = 0; 93 } 94 if (wrap) { 95 tlen = len; 96 for (t = ep - 1, len = 0; t >= p; --t, ++len) 97 if (*t == '\n') { 98 if (len) { 99 WR(t + 1, len); 100 len = 0; 101 } 102 if (tlen) { 103 WR(sp, tlen); 104 tlen = 0; 105 } 106 } 107 if (len) 108 WR(t + 1, len); 109 if (tlen) 110 WR(sp, tlen); 111 } 112 } else { 113 if (wrap && (len = ep - p)) 114 WR(p, len); 115 len = p - sp; 116 if (len) 117 WR(sp, len); 118 } 119 120 free(sp); 121 return 0; 122} 123 124/* 125 * lines -- read lines to an offset from the end and display. 126 * 127 * This is the function that reads to a line offset from the end of the input, 128 * storing the data in an array of buffers which is then displayed. If the 129 * rflag is set, the data is displayed in lines in reverse order, and this 130 * routine has the usual nastiness of trying to find the newlines. Otherwise, 131 * it is displayed from the line closest to the beginning of the input to 132 * the end. 133 */ 134int 135lines(FILE *fp, const char *fn, off_t off) 136{ 137 struct { 138 int blen; 139 u_int len; 140 char *l; 141 } *llines; 142 int ch, rc; 143 char *p, *sp; 144 int blen, cnt, recno, wrap; 145 146 if ((llines = malloc(off * sizeof(*llines))) == NULL) 147 err(1, "malloc"); 148 bzero(llines, off * sizeof(*llines)); 149 p = sp = NULL; 150 blen = cnt = recno = wrap = 0; 151 rc = 0; 152 153 while ((ch = getc(fp)) != EOF) { 154 if (++cnt > blen) { 155 if ((sp = realloc(sp, blen += 1024)) == NULL) 156 err(1, "realloc"); 157 p = sp + cnt - 1; 158 } 159 *p++ = ch; 160 if (ch == '\n') { 161 if ((int)llines[recno].blen < cnt) { 162 llines[recno].blen = cnt + 256; 163 if ((llines[recno].l = realloc(llines[recno].l, 164 llines[recno].blen)) == NULL) 165 err(1, "realloc"); 166 } 167 bcopy(sp, llines[recno].l, llines[recno].len = cnt); 168 cnt = 0; 169 p = sp; 170 if (++recno == off) { 171 wrap = 1; 172 recno = 0; 173 } 174 } 175 } 176 if (ferror(fp)) { 177 ierr(fn); 178 rc = 1; 179 goto done; 180 } 181 if (cnt) { 182 llines[recno].l = sp; 183 sp = NULL; 184 llines[recno].len = cnt; 185 if (++recno == off) { 186 wrap = 1; 187 recno = 0; 188 } 189 } 190 191 if (rflag) { 192 for (cnt = recno - 1; cnt >= 0; --cnt) 193 WR(llines[cnt].l, llines[cnt].len); 194 if (wrap) 195 for (cnt = off - 1; cnt >= recno; --cnt) 196 WR(llines[cnt].l, llines[cnt].len); 197 } else { 198 if (wrap) 199 for (cnt = recno; cnt < off; ++cnt) 200 WR(llines[cnt].l, llines[cnt].len); 201 for (cnt = 0; cnt < recno; ++cnt) 202 WR(llines[cnt].l, llines[cnt].len); 203 } 204done: 205 for (cnt = 0; cnt < off; cnt++) 206 free(llines[cnt].l); 207 free(sp); 208 free(llines); 209 return (rc); 210} 211