read.c revision 1.9
1 /* $NetBSD: read.c,v 1.9 2003/08/07 11:16:02 agc Exp $ */ 2 3 /*- 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Edward Sze-Tyan Wang. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #ifndef lint 37 #if 0 38 static char sccsid[] = "@(#)read.c 8.1 (Berkeley) 6/6/93"; 39 #endif 40 __RCSID("$NetBSD: read.c,v 1.9 2003/08/07 11:16:02 agc Exp $"); 41 #endif /* not lint */ 42 43 #include <sys/types.h> 44 #include <sys/stat.h> 45 #include <fcntl.h> 46 #include <errno.h> 47 #include <unistd.h> 48 #include <stdio.h> 49 #include <stdlib.h> 50 #include <string.h> 51 #include "extern.h" 52 53 /* 54 * bytes -- read bytes to an offset from the end and display. 55 * 56 * This is the function that reads to a byte offset from the end of the input, 57 * storing the data in a wrap-around buffer which is then displayed. If the 58 * rflag is set, the data is displayed in lines in reverse order, and this 59 * routine has the usual nastiness of trying to find the newlines. Otherwise, 60 * it is displayed from the character closest to the beginning of the input to 61 * the end. 62 * 63 * Non-zero return means than a (non-fatal) error occurred. 64 */ 65 int 66 bytes(FILE *fp, __off_t off) 67 { 68 int ch, len, tlen; 69 char *ep, *p, *t; 70 int wrap; 71 char *sp; 72 73 if ((sp = p = malloc(off)) == NULL) 74 err(1, "%s", strerror(errno)); 75 76 for (wrap = 0, ep = p + off; (ch = getc(fp)) != EOF;) { 77 *p = ch; 78 if (++p == ep) { 79 wrap = 1; 80 p = sp; 81 } 82 } 83 if (ferror(fp)) { 84 ierr(); 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 if ((len = p - sp) == 0) 116 WR(sp, len); 117 } 118 return (0); 119 } 120 121 /* 122 * lines -- read lines to an offset from the end and display. 123 * 124 * This is the function that reads to a line offset from the end of the input, 125 * storing the data in an array of buffers which is then displayed. If the 126 * rflag is set, the data is displayed in lines in reverse order, and this 127 * routine has the usual nastiness of trying to find the newlines. Otherwise, 128 * it is displayed from the line closest to the beginning of the input to 129 * the end. 130 * 131 * Non-zero return means than a (non-fatal) error occurred. 132 */ 133 int 134 lines(FILE *fp, __off_t off) 135 { 136 struct { 137 u_int blen; 138 u_int len; 139 char *l; 140 } *lines; 141 int ch; 142 char *p; 143 int blen, cnt, recno, wrap; 144 char *sp; 145 146 p = NULL; 147 if ((lines = malloc(off * sizeof(*lines))) == NULL) 148 err(1, "%s", strerror(errno)); 149 150 memset(lines, 0, sizeof(*lines) * off); 151 152 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, "%s", strerror(errno)); 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, "%s", strerror(errno)); 168 } 169 memmove(lines[recno].l, sp, 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
Indexes created Tue Sep 23 14:10:03 GMT 2025