read.c revision 87712
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 87712 2001-12-12 00:01:16Z markm $"); 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(fp, off) 70 FILE *fp; 71 off_t off; 72{ 73 int ch, len, tlen; 74 char *ep, *p, *t; 75 int wrap; 76 char *sp; 77 78 if ((sp = p = malloc(off)) == NULL) 79 err(1, "malloc"); 80 81 for (wrap = 0, ep = p + off; (ch = getc(fp)) != EOF;) { 82 *p = ch; 83 if (++p == ep) { 84 wrap = 1; 85 p = sp; 86 } 87 } 88 if (ferror(fp)) { 89 ierr(); 90 return 1; 91 } 92 93 if (rflag) { 94 for (t = p - 1, len = 0; t >= sp; --t, ++len) 95 if (*t == '\n' && len) { 96 WR(t + 1, len); 97 len = 0; 98 } 99 if (wrap) { 100 tlen = len; 101 for (t = ep - 1, len = 0; t >= p; --t, ++len) 102 if (*t == '\n') { 103 if (len) { 104 WR(t + 1, len); 105 len = 0; 106 } 107 if (tlen) { 108 WR(sp, tlen); 109 tlen = 0; 110 } 111 } 112 if (len) 113 WR(t + 1, len); 114 if (tlen) 115 WR(sp, tlen); 116 } 117 } else { 118 if (wrap && (len = ep - p)) 119 WR(p, len); 120 len = p - sp; 121 if (len) 122 WR(sp, len); 123 } 124 return 0; 125} 126 127/* 128 * lines -- read lines to an offset from the end and display. 129 * 130 * This is the function that reads to a line offset from the end of the input, 131 * storing the data in an array of buffers which is then displayed. If the 132 * rflag is set, the data is displayed in lines in reverse order, and this 133 * routine has the usual nastiness of trying to find the newlines. Otherwise, 134 * it is displayed from the line closest to the beginning of the input to 135 * the end. 136 */ 137int 138lines(fp, off) 139 FILE *fp; 140 off_t off; 141{ 142 struct { 143 u_int blen; 144 u_int len; 145 char *l; 146 } *llines; 147 int ch; 148 char *p, *sp; 149 int recno, wrap; 150 u_int cnt, blen; 151 152 if ((llines = malloc(off * sizeof(*llines))) == NULL) 153 err(1, "malloc"); 154 bzero(llines, off * sizeof(*llines)); 155 sp = NULL; 156 blen = cnt = recno = wrap = 0; 157 158 while ((ch = getc(fp)) != EOF) { 159 if (++cnt > blen) { 160 if ((sp = realloc(sp, blen += 1024)) == NULL) 161 err(1, "realloc"); 162 p = sp + cnt - 1; 163 } 164 *p++ = ch; 165 if (ch == '\n') { 166 if (llines[recno].blen < cnt) { 167 llines[recno].blen = cnt + 256; 168 if ((llines[recno].l = realloc(llines[recno].l, 169 llines[recno].blen)) == NULL) 170 err(1, "realloc"); 171 } 172 bcopy(sp, llines[recno].l, llines[recno].len = cnt); 173 cnt = 0; 174 p = sp; 175 if (++recno == off) { 176 wrap = 1; 177 recno = 0; 178 } 179 } 180 } 181 if (ferror(fp)) { 182 ierr(); 183 return 1; 184 } 185 if (cnt) { 186 llines[recno].l = sp; 187 llines[recno].len = cnt; 188 if (++recno == off) { 189 wrap = 1; 190 recno = 0; 191 } 192 } 193 194 if (rflag) { 195 for (cnt = recno - 1; cnt != 0; --cnt) 196 WR(llines[cnt].l, llines[cnt].len); 197 if (wrap) 198 for (cnt = off - 1; cnt >= (u_int)recno; --cnt) 199 WR(llines[cnt].l, llines[cnt].len); 200 } else { 201 if (wrap) 202 for (cnt = recno; cnt < (u_int)off; ++cnt) 203 WR(llines[cnt].l, llines[cnt].len); 204 for (cnt = 0; cnt < (u_int)recno; ++cnt) 205 WR(llines[cnt].l, llines[cnt].len); 206 } 207 return 0; 208} 209