read.c revision 69528
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 39static char sccsid[] = "@(#)read.c 8.1 (Berkeley) 6/6/93"; 40#endif 41static const char rcsid[] = 42 "$FreeBSD: head/usr.bin/tail/read.c 69528 2000-12-02 19:10:12Z asmodai $"; 43#endif /* not lint */ 44 45#include <sys/types.h> 46#include <sys/stat.h> 47#include <fcntl.h> 48#include <errno.h> 49#include <unistd.h> 50#include <stdio.h> 51#include <stdlib.h> 52#include <string.h> 53#include <err.h> 54#include "extern.h" 55 56/* 57 * bytes -- read bytes to an offset from the end and display. 58 * 59 * This is the function that reads to a byte offset from the end of the input, 60 * storing the data in a wrap-around buffer which is then displayed. If the 61 * rflag is set, the data is displayed in lines in reverse order, and this 62 * routine has the usual nastiness of trying to find the newlines. Otherwise, 63 * it is displayed from the character closest to the beginning of the input to 64 * the end. 65 */ 66int 67bytes(fp, off) 68 register FILE *fp; 69 off_t off; 70{ 71 register int ch, len, tlen; 72 register 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 if (len = p - sp) 119 WR(sp, len); 120 } 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(fp, off) 136 register FILE *fp; 137 off_t off; 138{ 139 struct { 140 u_int blen; 141 u_int len; 142 char *l; 143 } *lines; 144 register int ch; 145 register char *p; 146 int blen, cnt, recno, wrap; 147 char *sp; 148 149 if ((lines = malloc(off * sizeof(*lines))) == NULL) 150 err(1, "malloc"); 151 bzero(lines, off * sizeof(*lines)); 152 sp = NULL; 153 blen = cnt = recno = wrap = 0; 154 155 while ((ch = getc(fp)) != EOF) { 156 if (++cnt > blen) { 157 if ((sp = realloc(sp, blen += 1024)) == NULL) 158 err(1, "realloc"); 159 p = sp + cnt - 1; 160 } 161 *p++ = ch; 162 if (ch == '\n') { 163 if (lines[recno].blen < cnt) { 164 lines[recno].blen = cnt + 256; 165 if ((lines[recno].l = realloc(lines[recno].l, 166 lines[recno].blen)) == NULL) 167 err(1, "realloc"); 168 } 169 bcopy(sp, lines[recno].l, lines[recno].len = cnt); 170 cnt = 0; 171 p = sp; 172 if (++recno == off) { 173 wrap = 1; 174 recno = 0; 175 } 176 } 177 } 178 if (ferror(fp)) { 179 ierr(); 180 return 1; 181 } 182 if (cnt) { 183 lines[recno].l = sp; 184 lines[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(lines[cnt].l, lines[cnt].len); 194 if (wrap) 195 for (cnt = off - 1; cnt >= recno; --cnt) 196 WR(lines[cnt].l, lines[cnt].len); 197 } else { 198 if (wrap) 199 for (cnt = recno; cnt < off; ++cnt) 200 WR(lines[cnt].l, lines[cnt].len); 201 for (cnt = 0; cnt < recno; ++cnt) 202 WR(lines[cnt].l, lines[cnt].len); 203 } 204 return 0; 205} 206