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1.3 ! deraadt 1: /* $OpenBSD: forward.c,v 1.7 1996/02/13 16:49:10 ghudson Exp $ */
1.2 niklas 2: /* $NetBSD: forward.c,v 1.7 1996/02/13 16:49:10 ghudson Exp $ */
1.1 deraadt 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.
19: * 3. All advertising materials mentioning features or use of this software
20: * must display the following acknowledgement:
21: * This product includes software developed by the University of
22: * California, Berkeley and its contributors.
23: * 4. Neither the name of the University nor the names of its contributors
24: * may be used to endorse or promote products derived from this software
25: * without specific prior written permission.
26: *
27: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37: * SUCH DAMAGE.
38: */
39:
40: #ifndef lint
41: #if 0
42: static char sccsid[] = "@(#)forward.c 8.1 (Berkeley) 6/6/93";
43: #endif
1.3 ! deraadt 44: static char rcsid[] = "$OpenBSD: forward.c,v 1.7 1996/02/13 16:49:10 ghudson Exp $";
1.1 deraadt 45: #endif /* not lint */
46:
47: #include <sys/types.h>
48: #include <sys/stat.h>
49: #include <sys/time.h>
50: #include <sys/mman.h>
51:
52: #include <limits.h>
53: #include <fcntl.h>
54: #include <errno.h>
55: #include <unistd.h>
56: #include <stdio.h>
57: #include <stdlib.h>
58: #include <string.h>
59: #include "extern.h"
60:
61: static void rlines __P((FILE *, long, struct stat *));
62:
63: /*
64: * forward -- display the file, from an offset, forward.
65: *
66: * There are eight separate cases for this -- regular and non-regular
67: * files, by bytes or lines and from the beginning or end of the file.
68: *
69: * FBYTES byte offset from the beginning of the file
70: * REG seek
71: * NOREG read, counting bytes
72: *
73: * FLINES line offset from the beginning of the file
74: * REG read, counting lines
75: * NOREG read, counting lines
76: *
77: * RBYTES byte offset from the end of the file
78: * REG seek
79: * NOREG cyclically read characters into a wrap-around buffer
80: *
81: * RLINES
82: * REG mmap the file and step back until reach the correct offset.
83: * NOREG cyclically read lines into a wrap-around array of buffers
84: */
85: void
86: forward(fp, style, off, sbp)
87: FILE *fp;
88: enum STYLE style;
89: long off;
90: struct stat *sbp;
91: {
92: register int ch;
93: struct timeval second;
94:
95: switch(style) {
96: case FBYTES:
97: if (off == 0)
98: break;
99: if (S_ISREG(sbp->st_mode)) {
100: if (sbp->st_size < off)
101: off = sbp->st_size;
102: if (fseek(fp, off, SEEK_SET) == -1) {
103: ierr();
104: return;
105: }
106: } else while (off--)
107: if ((ch = getc(fp)) == EOF) {
108: if (ferror(fp)) {
109: ierr();
110: return;
111: }
112: break;
113: }
114: break;
115: case FLINES:
116: if (off == 0)
117: break;
118: for (;;) {
119: if ((ch = getc(fp)) == EOF) {
120: if (ferror(fp)) {
121: ierr();
122: return;
123: }
124: break;
125: }
126: if (ch == '\n' && !--off)
127: break;
128: }
129: break;
130: case RBYTES:
131: if (S_ISREG(sbp->st_mode)) {
132: if (sbp->st_size >= off &&
133: fseek(fp, -off, SEEK_END) == -1) {
134: ierr();
135: return;
136: }
137: } else if (off == 0) {
138: while (getc(fp) != EOF);
139: if (ferror(fp)) {
140: ierr();
141: return;
142: }
143: } else
144: bytes(fp, off);
145: break;
146: case RLINES:
147: if (S_ISREG(sbp->st_mode))
148: if (!off) {
149: if (fseek(fp, 0L, SEEK_END) == -1) {
150: ierr();
151: return;
152: }
153: } else
154: rlines(fp, off, sbp);
155: else if (off == 0) {
156: while (getc(fp) != EOF);
157: if (ferror(fp)) {
158: ierr();
159: return;
160: }
161: } else
162: lines(fp, off);
163: break;
164: }
165:
166: for (;;) {
167: while ((ch = getc(fp)) != EOF)
168: if (putchar(ch) == EOF)
169: oerr();
170: if (ferror(fp)) {
171: ierr();
172: return;
173: }
174: (void)fflush(stdout);
175: if (!fflag)
176: break;
1.2 niklas 177: /*
178: * We pause for one second after displaying any data that has
179: * accumulated since we read the file. Since sleep(3) takes
180: * eight system calls, use select() instead.
181: */
182: second.tv_sec = 1;
183: second.tv_usec = 0;
184: if (select(0, NULL, NULL, NULL, &second) == -1)
1.1 deraadt 185: err(1, "select: %s", strerror(errno));
186: clearerr(fp);
187: }
188: }
189:
190: /*
191: * rlines -- display the last offset lines of the file.
192: */
193: static void
194: rlines(fp, off, sbp)
195: FILE *fp;
196: long off;
197: struct stat *sbp;
198: {
199: register off_t size;
200: register char *p;
201: char *start;
202:
203: if (!(size = sbp->st_size))
204: return;
205:
206: if (size > SIZE_T_MAX) {
207: err(0, "%s: %s", fname, strerror(EFBIG));
208: return;
209: }
210:
211: if ((start = mmap(NULL, (size_t)size,
212: PROT_READ, 0, fileno(fp), (off_t)0)) == (caddr_t)-1) {
213: err(0, "%s: %s", fname, strerror(EFBIG));
214: return;
215: }
216:
217: /* Last char is special, ignore whether newline or not. */
218: for (p = start + size - 1; --size;)
219: if (*--p == '\n' && !--off) {
220: ++p;
221: break;
222: }
223:
224: /* Set the file pointer to reflect the length displayed. */
225: size = sbp->st_size - size;
226: WR(p, size);
227: if (fseek(fp, (long)sbp->st_size, SEEK_SET) == -1) {
228: ierr();
229: return;
230: }
231: if (munmap(start, (size_t)sbp->st_size)) {
232: err(0, "%s: %s", fname, strerror(errno));
233: return;
234: }
235: }