read.c revision 137157
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#include <sys/cdefs.h> 38 39__FBSDID("$FreeBSD: head/usr.bin/tail/read.c 137157 2004-11-03 15:23:11Z paul $"); 40 41#ifndef lint 42static const char sccsid[] = "@(#)read.c 8.1 (Berkeley) 6/6/93"; 43#endif 44 45#include <sys/types.h> 46#include <sys/stat.h> 47 48#include <err.h> 49#include <errno.h> 50#include <fcntl.h> 51#include <stdio.h> 52#include <stdlib.h> 53#include <string.h> 54#include <unistd.h> 55 56#include "extern.h" 57 58/* 59 * bytes -- read bytes to an offset from the end and display. 60 * 61 * This is the function that reads to a byte offset from the end of the input, 62 * storing the data in a wrap-around buffer which is then displayed. If the 63 * rflag is set, the data is displayed in lines in reverse order, and this 64 * routine has the usual nastiness of trying to find the newlines. Otherwise, 65 * it is displayed from the character closest to the beginning of the input to 66 * the end. 67 */ 68int 69bytes(FILE *fp, off_t off) 70{ 71 int ch, len, tlen; 72 char *ep, *p, *t; 73 int wrap; 74 char *sp; 75 76 if ((sp = p = malloc(off)) == NULL) 77 err(1, "malloc"); 78 79 for (wrap = 0, ep = p + off; (ch = getc(fp)) != EOF;) { 80 *p = ch; 81 if (++p == ep) { 82 wrap = 1; 83 p = sp; 84 } 85 } 86 if (ferror(fp)) { 87 ierr(); 88 return 1; 89 } 90 91 if (rflag) { 92 for (t = p - 1, len = 0; t >= sp; --t, ++len) 93 if (*t == '\n' && len) { 94 WR(t + 1, len); 95 len = 0; 96 } 97 if (wrap) { 98 tlen = len; 99 for (t = ep - 1, len = 0; t >= p; --t, ++len) 100 if (*t == '\n') { 101 if (len) { 102 WR(t + 1, len); 103 len = 0; 104 } 105 if (tlen) { 106 WR(sp, tlen); 107 tlen = 0; 108 } 109 } 110 if (len) 111 WR(t + 1, len); 112 if (tlen) 113 WR(sp, tlen); 114 } 115 } else { 116 if (wrap && (len = ep - p)) 117 WR(p, len); 118 len = p - sp; 119 if (len) 120 WR(sp, len); 121 } 122 return 0; 123} 124 125/* 126 * lines -- read lines to an offset from the end and display. 127 * 128 * This is the function that reads to a line offset from the end of the input, 129 * storing the data in an array of buffers which is then displayed. If the 130 * rflag is set, the data is displayed in lines in reverse order, and this 131 * routine has the usual nastiness of trying to find the newlines. Otherwise, 132 * it is displayed from the line closest to the beginning of the input to 133 * the end. 134 */ 135int 136lines(FILE *fp, off_t off) 137{ 138 struct { 139 int blen; 140 u_int len; 141 char *l; 142 } *llines; 143 int ch; 144 char *p, *sp; 145 int blen, cnt, recno, wrap; 146 147 if ((llines = malloc(off * sizeof(*llines))) == NULL) 148 err(1, "malloc"); 149 bzero(llines, off * sizeof(*llines)); 150 sp = NULL; 151 blen = cnt = recno = wrap = 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(); 178 return 1; 179 } 180 if (cnt) { 181 llines[recno].l = sp; 182 llines[recno].len = cnt; 183 if (++recno == off) { 184 wrap = 1; 185 recno = 0; 186 } 187 } 188 189 if (rflag) { 190 for (cnt = recno - 1; cnt >= 0; --cnt) 191 WR(llines[cnt].l, llines[cnt].len); 192 if (wrap) 193 for (cnt = off - 1; cnt >= recno; --cnt) 194 WR(llines[cnt].l, llines[cnt].len); 195 } else { 196 if (wrap) 197 for (cnt = recno; cnt < off; ++cnt) 198 WR(llines[cnt].l, llines[cnt].len); 199 for (cnt = 0; cnt < recno; ++cnt) 200 WR(llines[cnt].l, llines[cnt].len); 201 } 202 return 0; 203} 204