Annotation of src/usr.bin/tail/read.c, Revision 1.1
1.1 ! deraadt 1: /* $NetBSD: read.c,v 1.4 1994/11/23 07:42:07 jtc 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. All advertising materials mentioning features or use of this software
! 19: * must display the following acknowledgement:
! 20: * This product includes software developed by the University of
! 21: * California, Berkeley and its contributors.
! 22: * 4. Neither the name of the University nor the names of its contributors
! 23: * may be used to endorse or promote products derived from this software
! 24: * without specific prior written permission.
! 25: *
! 26: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
! 27: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
! 28: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
! 29: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
! 30: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
! 31: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
! 32: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
! 33: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
! 34: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
! 35: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
! 36: * SUCH DAMAGE.
! 37: */
! 38:
! 39: #ifndef lint
! 40: #if 0
! 41: static char sccsid[] = "@(#)read.c 8.1 (Berkeley) 6/6/93";
! 42: #endif
! 43: static char rcsid[] = "$NetBSD: read.c,v 1.4 1994/11/23 07:42:07 jtc Exp $";
! 44: #endif /* not lint */
! 45:
! 46: #include <sys/types.h>
! 47: #include <sys/stat.h>
! 48: #include <fcntl.h>
! 49: #include <errno.h>
! 50: #include <unistd.h>
! 51: #include <stdio.h>
! 52: #include <stdlib.h>
! 53: #include <string.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: */
! 66: void
! 67: bytes(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, "%s", strerror(errno));
! 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;
! 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: }
! 122:
! 123: /*
! 124: * lines -- read lines to an offset from the end and display.
! 125: *
! 126: * This is the function that reads to a line offset from the end of the input,
! 127: * storing the data in an array of buffers which is then displayed. If the
! 128: * rflag is set, the data is displayed in lines in reverse order, and this
! 129: * routine has the usual nastiness of trying to find the newlines. Otherwise,
! 130: * it is displayed from the line closest to the beginning of the input to
! 131: * the end.
! 132: */
! 133: void
! 134: lines(fp, off)
! 135: register FILE *fp;
! 136: off_t off;
! 137: {
! 138: struct {
! 139: u_int blen;
! 140: u_int len;
! 141: char *l;
! 142: } *lines;
! 143: register int ch;
! 144: register char *p;
! 145: int blen, cnt, recno, wrap;
! 146: char *sp;
! 147:
! 148: if ((lines = malloc(off * sizeof(*lines))) == NULL)
! 149: err(1, "%s", strerror(errno));
! 150:
! 151: sp = NULL;
! 152: blen = cnt = recno = wrap = 0;
! 153:
! 154: while ((ch = getc(fp)) != EOF) {
! 155: if (++cnt > blen) {
! 156: if ((sp = realloc(sp, blen += 1024)) == NULL)
! 157: err(1, "%s", strerror(errno));
! 158: p = sp + cnt - 1;
! 159: }
! 160: *p++ = ch;
! 161: if (ch == '\n') {
! 162: if (lines[recno].blen < cnt) {
! 163: lines[recno].blen = cnt + 256;
! 164: if ((lines[recno].l = realloc(lines[recno].l,
! 165: lines[recno].blen)) == NULL)
! 166: err(1, "%s", strerror(errno));
! 167: }
! 168: bcopy(sp, lines[recno].l, lines[recno].len = cnt);
! 169: cnt = 0;
! 170: p = sp;
! 171: if (++recno == off) {
! 172: wrap = 1;
! 173: recno = 0;
! 174: }
! 175: }
! 176: }
! 177: if (ferror(fp)) {
! 178: ierr();
! 179: return;
! 180: }
! 181: if (cnt) {
! 182: lines[recno].l = sp;
! 183: lines[recno].len = cnt;
! 184: if (++recno == off) {
! 185: wrap = 1;
! 186: recno = 0;
! 187: }
! 188: }
! 189:
! 190: if (rflag) {
! 191: for (cnt = recno - 1; cnt >= 0; --cnt)
! 192: WR(lines[cnt].l, lines[cnt].len);
! 193: if (wrap)
! 194: for (cnt = off - 1; cnt >= recno; --cnt)
! 195: WR(lines[cnt].l, lines[cnt].len);
! 196: } else {
! 197: if (wrap)
! 198: for (cnt = recno; cnt < off; ++cnt)
! 199: WR(lines[cnt].l, lines[cnt].len);
! 200: for (cnt = 0; cnt < recno; ++cnt)
! 201: WR(lines[cnt].l, lines[cnt].len);
! 202: }
! 203: }
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