Annotation of src/usr.bin/tail/read.c, Revision 1.12
1.12 ! otto 1: /* $OpenBSD: read.c,v 1.11 2007/09/16 18:07:40 otto Exp $ */
1.1 deraadt 2: /* $NetBSD: read.c,v 1.4 1994/11/23 07:42:07 jtc Exp $ */
3:
4: /*-
5: * Copyright (c) 1991, 1993
6: * The Regents of the University of California. All rights reserved.
7: *
8: * This code is derived from software contributed to Berkeley by
9: * Edward Sze-Tyan Wang.
10: *
11: * Redistribution and use in source and binary forms, with or without
12: * modification, are permitted provided that the following conditions
13: * are met:
14: * 1. Redistributions of source code must retain the above copyright
15: * notice, this list of conditions and the following disclaimer.
16: * 2. Redistributions in binary form must reproduce the above copyright
17: * notice, this list of conditions and the following disclaimer in the
18: * documentation and/or other materials provided with the distribution.
1.7 millert 19: * 3. Neither the name of the University nor the names of its contributors
1.1 deraadt 20: * may be used to endorse or promote products derived from this software
21: * without specific prior written permission.
22: *
23: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33: * SUCH DAMAGE.
34: */
35:
36: #ifndef lint
37: #if 0
38: static char sccsid[] = "@(#)read.c 8.1 (Berkeley) 6/6/93";
39: #endif
1.12 ! otto 40: static char rcsid[] = "$OpenBSD: read.c,v 1.11 2007/09/16 18:07:40 otto Exp $";
1.1 deraadt 41: #endif /* not lint */
42:
43: #include <sys/types.h>
44: #include <sys/stat.h>
1.8 kjell 45: #include <sys/limits.h>
1.3 millert 46:
47: #include <err.h>
1.1 deraadt 48: #include <stdio.h>
49: #include <stdlib.h>
50: #include <string.h>
1.3 millert 51: #include <unistd.h>
52:
1.1 deraadt 53: #include "extern.h"
54:
55: /*
56: * bytes -- read bytes to an offset from the end and display.
57: *
58: * This is the function that reads to a byte offset from the end of the input,
59: * storing the data in a wrap-around buffer which is then displayed. If the
60: * rflag is set, the data is displayed in lines in reverse order, and this
61: * routine has the usual nastiness of trying to find the newlines. Otherwise,
62: * it is displayed from the character closest to the beginning of the input to
63: * the end.
1.4 ericj 64: *
1.5 mpech 65: * A non-zero return means an (non-fatal) error occurred.
1.4 ericj 66: *
1.1 deraadt 67: */
1.4 ericj 68: int
1.9 kjell 69: bytes(FILE *fp, off_t off)
1.1 deraadt 70: {
1.8 kjell 71: int ch;
72: size_t len, tlen;
1.6 mpech 73: char *ep, *p, *t;
1.1 deraadt 74: int wrap;
75: char *sp;
76:
1.8 kjell 77: if (off > SIZE_T_MAX)
78: errx(1, "offset too large");
79:
1.1 deraadt 80: if ((sp = p = malloc(off)) == NULL)
1.3 millert 81: err(1, NULL);
1.1 deraadt 82:
83: for (wrap = 0, ep = p + off; (ch = getc(fp)) != EOF;) {
84: *p = ch;
85: if (++p == ep) {
86: wrap = 1;
87: p = sp;
88: }
89: }
90: if (ferror(fp)) {
91: ierr();
1.10 otto 92: free(sp);
1.4 ericj 93: return(1);
1.1 deraadt 94: }
95:
96: if (rflag) {
97: for (t = p - 1, len = 0; t >= sp; --t, ++len)
98: if (*t == '\n' && len) {
99: WR(t + 1, len);
100: len = 0;
101: }
102: if (wrap) {
103: tlen = len;
104: for (t = ep - 1, len = 0; t >= p; --t, ++len)
105: if (*t == '\n') {
106: if (len) {
107: WR(t + 1, len);
108: len = 0;
109: }
110: if (tlen) {
111: WR(sp, tlen);
112: tlen = 0;
113: }
114: }
115: if (len)
116: WR(t + 1, len);
117: if (tlen)
118: WR(sp, tlen);
119: }
120: } else {
121: if (wrap && (len = ep - p))
122: WR(p, len);
1.3 millert 123: if ((len = p - sp))
1.1 deraadt 124: WR(sp, len);
125: }
1.10 otto 126:
127: free(sp);
1.4 ericj 128: return(0);
1.1 deraadt 129: }
130:
131: /*
132: * lines -- read lines to an offset from the end and display.
133: *
134: * This is the function that reads to a line offset from the end of the input,
135: * storing the data in an array of buffers which is then displayed. If the
136: * rflag is set, the data is displayed in lines in reverse order, and this
137: * routine has the usual nastiness of trying to find the newlines. Otherwise,
138: * it is displayed from the line closest to the beginning of the input to
139: * the end.
1.4 ericj 140: *
1.5 mpech 141: * A non-zero return means an (non-fatal) error occurred.
1.4 ericj 142: *
1.1 deraadt 143: */
1.4 ericj 144: int
1.9 kjell 145: lines(FILE *fp, off_t off)
1.1 deraadt 146: {
147: struct {
1.8 kjell 148: size_t blen;
149: size_t len;
1.1 deraadt 150: char *l;
151: } *lines;
1.11 otto 152: int ch, rc = 0;
1.6 mpech 153: char *p = NULL;
1.8 kjell 154: int wrap;
155: size_t cnt, recno, blen, newsize;
156: char *sp = NULL, *newp = NULL;
157:
158: if (off > SIZE_T_MAX)
159: errx(1, "offset too large");
1.1 deraadt 160:
1.3 millert 161: if ((lines = calloc(off, sizeof(*lines))) == NULL)
162: err(1, NULL);
1.1 deraadt 163:
164: blen = cnt = recno = wrap = 0;
165:
166: while ((ch = getc(fp)) != EOF) {
167: if (++cnt > blen) {
1.8 kjell 168: newsize = blen + 1024;
169: if ((newp = realloc(sp, newsize)) == NULL)
1.3 millert 170: err(1, NULL);
1.8 kjell 171: sp = newp;
172: blen = newsize;
1.1 deraadt 173: p = sp + cnt - 1;
174: }
175: *p++ = ch;
176: if (ch == '\n') {
177: if (lines[recno].blen < cnt) {
1.8 kjell 178: newsize = cnt + 256;
179: if ((newp = realloc(lines[recno].l,
180: newsize)) == NULL)
1.3 millert 181: err(1, NULL);
1.8 kjell 182: lines[recno].l = newp;
183: lines[recno].blen = newsize;
1.1 deraadt 184: }
1.3 millert 185: memcpy(lines[recno].l, sp, (lines[recno].len = cnt));
1.1 deraadt 186: cnt = 0;
187: p = sp;
188: if (++recno == off) {
189: wrap = 1;
190: recno = 0;
191: }
192: }
193: }
194: if (ferror(fp)) {
195: ierr();
1.11 otto 196: rc = 1;
197: goto done;
1.1 deraadt 198: }
199: if (cnt) {
200: lines[recno].l = sp;
201: lines[recno].len = cnt;
202: if (++recno == off) {
203: wrap = 1;
204: recno = 0;
205: }
206: }
207:
208: if (rflag) {
1.8 kjell 209: for (cnt = recno; cnt > 0; --cnt)
210: WR(lines[cnt - 1].l, lines[cnt - 1].len);
1.1 deraadt 211: if (wrap)
1.8 kjell 212: for (cnt = off; cnt > recno; --cnt)
213: WR(lines[cnt - 1].l, lines[cnt - 1].len);
1.1 deraadt 214: } else {
215: if (wrap)
216: for (cnt = recno; cnt < off; ++cnt)
217: WR(lines[cnt].l, lines[cnt].len);
218: for (cnt = 0; cnt < recno; ++cnt)
219: WR(lines[cnt].l, lines[cnt].len);
220: }
1.11 otto 221: done:
222: for (cnt = 0; cnt < off; cnt++)
223: free(lines[cnt].l);
224: free(sp);
225: free(lines);
226: return(rc);
1.1 deraadt 227: }
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