xref: /openbsd-src/usr.bin/compress/nullopen.c (revision a28daedfc357b214be5c701aa8ba8adb29a7f1c2)
1 /*	$OpenBSD: nullopen.c,v 1.3 2005/06/26 18:20:26 otto Exp $	*/
2 
3 /*
4  * Copyright (c) 2003 Can Erkin Acar
5  * Copyright (c) 1997 Michael Shalayeff
6  * All rights reserved.
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  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  */
30 
31 const char null_rcsid[] =
32     "$OpenBSD: nullopen.c,v 1.3 2005/06/26 18:20:26 otto Exp $";
33 
34 #include <sys/types.h>
35 #include <stdio.h>
36 #include <stdlib.h>
37 #include <errno.h>
38 #include <unistd.h>
39 #include "compress.h"
40 
41 typedef struct {
42 	off_t 	  total_in;
43 	off_t 	  total_out;
44 	int   	  fd;
45 	int       gotmagic;
46 	char	  mode;
47 } null_stream;
48 
49 char null_magic[2];
50 
51 
52 void *
53 null_open(int fd, const char *mode, char *name, int bits,
54     u_int32_t mtime, int gotmagic)
55 {
56 	null_stream *s;
57 
58 	if (fd < 0 || !mode)
59 		return NULL;
60 
61 	if ((mode[0] != 'r' && mode[0] != 'w') || mode[1] != '\0') {
62 		errno = EINVAL;
63 		return NULL;
64 	}
65 
66 	if ((s = (null_stream *) calloc(1, sizeof(null_stream))) == NULL)
67 		return NULL;
68 
69 	s->fd = fd;
70 	s->gotmagic = gotmagic;
71 	s->total_in = s->total_out = 0;
72 	s->mode = mode[0];
73 
74 	return s;
75 }
76 
77 int
78 null_close(void *cookie, struct z_info *info, const char *name, struct stat *sb)
79 {
80 	null_stream *s = (null_stream*) cookie;
81 	int err = 0;
82 
83 	if (s == NULL)
84 		return -1;
85 
86 
87 	if (info != NULL) {
88 		info->mtime = 0;
89 		info->crc =  (u_int32_t)-1;
90 		info->hlen = 0;
91 		info->total_in = (off_t) s->total_in;
92 		info->total_out = (off_t) s->total_out;
93 	}
94 
95 	setfile(name, s->fd, sb);
96 	err = close(s->fd);
97 
98 	free(s);
99 
100 	return err;
101 }
102 
103 int
104 null_flush(void *cookie, int flush)
105 {
106 	null_stream *s = (null_stream*)cookie;
107 
108 	if (s == NULL || s->mode != 'w') {
109 		errno = EBADF;
110 		return (-1);
111 	}
112 
113 	return 0;
114 }
115 
116 int
117 null_read(void *cookie, char *buf, int len)
118 {
119 	null_stream *s = (null_stream*)cookie;
120 
121 	if (s == NULL) {
122 		errno = EBADF;
123 		return (-1);
124 	}
125 	if (s->gotmagic) {
126 		if (len < 2) {
127 			errno = EBADF;
128 			return (-1);
129 		}
130 
131 		buf[0] = null_magic[0];
132 		buf[1] = null_magic[1];
133 		s->gotmagic = 0;
134 
135 		return (2);
136 	}
137 
138 	return read(s->fd, buf, len);
139 }
140 
141 int
142 null_write(void *cookie, const char *buf, int len)
143 {
144 	null_stream *s = (null_stream*)cookie;
145 
146 	if (s == NULL) {
147 		errno = EBADF;
148 		return (-1);
149 	}
150 
151 	return write(s->fd, buf, len);
152 }
153