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 * @(#)read.c 8.1 (Berkeley) 6/6/93 37 * $FreeBSD: src/usr.bin/tail/read.c,v 1.6.8.1 2001/01/24 08:41:14 ru Exp $ 38 * $DragonFly: src/usr.bin/tail/read.c,v 1.6 2008/02/05 14:35:43 matthias Exp $ 39 */ 40 41 #include <sys/types.h> 42 #include <sys/stat.h> 43 #include <fcntl.h> 44 #include <errno.h> 45 #include <unistd.h> 46 #include <stdio.h> 47 #include <stdlib.h> 48 #include <string.h> 49 #include <err.h> 50 #include "extern.h" 51 52 /* 53 * display_bytes -- read bytes to an offset from the end and display. 54 * 55 * This is the function that reads to a byte offset from the end of the input, 56 * storing the data in a wrap-around buffer which is then displayed. If the 57 * rflag is set, the data is displayed in lines in reverse order, and this 58 * routine has the usual nastiness of trying to find the newlines. Otherwise, 59 * it is displayed from the character closest to the beginning of the input to 60 * the end. 61 */ 62 int 63 display_bytes(FILE *fp, off_t off) 64 { 65 int ch, len, tlen; 66 char *ep, *p, *t; 67 int wrap; 68 char *sp; 69 70 if ((sp = p = malloc(off)) == NULL) 71 err(1, "malloc"); 72 73 for (wrap = 0, ep = p + off; (ch = getc(fp)) != EOF;) { 74 *p = ch; 75 if (++p == ep) { 76 wrap = 1; 77 p = sp; 78 } 79 } 80 if (ferror(fp)) { 81 ierr(); 82 free(sp); 83 return 1; 84 } 85 86 if (rflag) { 87 for (t = p - 1, len = 0; t >= sp; --t, ++len) 88 if (*t == '\n' && len) { 89 WR(t + 1, len); 90 len = 0; 91 } 92 if (wrap) { 93 tlen = len; 94 for (t = ep - 1, len = 0; t >= p; --t, ++len) 95 if (*t == '\n') { 96 if (len) { 97 WR(t + 1, len); 98 len = 0; 99 } 100 if (tlen) { 101 WR(sp, tlen); 102 tlen = 0; 103 } 104 } 105 if (len) 106 WR(t + 1, len); 107 if (tlen) 108 WR(sp, tlen); 109 } 110 } else { 111 if (wrap && (len = ep - p)) 112 WR(p, len); 113 if ((len = p - sp) != 0) 114 WR(sp, len); 115 } 116 free(sp); 117 return 0; 118 } 119 120 /* 121 * display_lines -- read lines to an offset from the end and display. 122 * 123 * This is the function that reads to a line offset from the end of the input, 124 * storing the data in an array of buffers which is then displayed. If the 125 * rflag is set, the data is displayed in lines in reverse order, and this 126 * routine has the usual nastiness of trying to find the newlines. Otherwise, 127 * it is displayed from the line closest to the beginning of the input to 128 * the end. 129 */ 130 int 131 display_lines(FILE *fp, off_t off) 132 { 133 struct { 134 ssize_t blen; 135 ssize_t len; 136 char *l; 137 } *lines; 138 int ch, rc = 0; 139 char *p = NULL; 140 int blen, cnt, recno, wrap; 141 char *sp; 142 143 if ((lines = malloc(off * sizeof(*lines))) == NULL) 144 err(1, "malloc"); 145 bzero(lines, off * sizeof(*lines)); 146 sp = NULL; 147 blen = cnt = recno = wrap = 0; 148 149 while ((ch = getc(fp)) != EOF) { 150 if (++cnt > blen) { 151 if ((sp = realloc(sp, blen += 1024)) == NULL) 152 err(1, "realloc"); 153 p = sp + cnt - 1; 154 } 155 *p++ = ch; 156 if (ch == '\n') { 157 if (lines[recno].blen < cnt) { 158 lines[recno].blen = cnt + 256; 159 if ((lines[recno].l = realloc(lines[recno].l, 160 lines[recno].blen)) == NULL) 161 err(1, "realloc"); 162 } 163 bcopy(sp, lines[recno].l, lines[recno].len = cnt); 164 cnt = 0; 165 p = sp; 166 if (++recno == off) { 167 wrap = 1; 168 recno = 0; 169 } 170 } 171 } 172 if (ferror(fp)) { 173 ierr(); 174 rc = 1; 175 goto out; 176 } 177 if (cnt) { 178 lines[recno].l = sp; 179 sp = NULL; 180 lines[recno].len = cnt; 181 if (++recno == off) { 182 wrap = 1; 183 recno = 0; 184 } 185 } 186 187 if (rflag) { 188 for (cnt = recno - 1; cnt >= 0; --cnt) 189 WR(lines[cnt].l, lines[cnt].len); 190 if (wrap) 191 for (cnt = off - 1; cnt >= recno; --cnt) 192 WR(lines[cnt].l, lines[cnt].len); 193 } else { 194 if (wrap) 195 for (cnt = recno; cnt < off; ++cnt) 196 WR(lines[cnt].l, lines[cnt].len); 197 for (cnt = 0; cnt < recno; ++cnt) 198 WR(lines[cnt].l, lines[cnt].len); 199 } 200 out: 201 for (cnt = 0; cnt < off; cnt++) 202 free(lines[cnt].l); 203 free(sp); 204 free(lines); 205 return (rc); 206 } 207