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[dragonfly.git] / usr.bin / compress / zopen.3
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1.\" Copyright (c) 1992, 1993
2.\" The Regents of the University of California. All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\" notice, this list of conditions and the following disclaimer.
9.\" 2. Redistributions in binary form must reproduce the above copyright
10.\" notice, this list of conditions and the following disclaimer in the
11.\" documentation and/or other materials provided with the distribution.
dc71b7ab 12.\" 3. Neither the name of the University nor the names of its contributors
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13.\" may be used to endorse or promote products derived from this software
14.\" without specific prior written permission.
15.\"
16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26.\" SUCH DAMAGE.
27.\"
28.\" @(#)zopen.3 8.1 (Berkeley) 6/9/93
29.\" $FreeBSD: src/usr.bin/compress/zopen.3,v 1.5.2.3 2001/12/14 15:53:29 ru Exp $
1de703da 30.\" $DragonFly: src/usr.bin/compress/zopen.3,v 1.2 2003/06/17 04:29:25 dillon Exp $
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31.\"
32.Dd June 9, 1993
33.Dt ZOPEN 3
34.Os
35.Sh NAME
36.Nm zopen
37.Nd compressed stream open function
38.Sh SYNOPSIS
39.Fd #include \&"zopen.h\&"
40.Ft FILE *
41.Fn zopen "const char *path" "const char *mode" "int bits"
42.Sh DESCRIPTION
43The
44.Fn zopen
45function
46opens the compressed file whose name is the string pointed to by
47.Fa path
48and associates a stream with it.
49.Pp
50The argument
51.Fa mode
52points to one of the following one-character strings:
53.Bl -tag -width indent
54.It Dq Li r
55Open compressed file for reading.
56The stream is positioned at the beginning of the file.
57.It Dq Li w
58Truncate file to zero length or create compressed file for writing.
59The stream is positioned at the beginning of the file.
60.El
61.Pp
62Any created files will have mode
63.Pf \\*q Dv S_IRUSR
64\&|
65.Dv S_IWUSR
66\&|
67.Dv S_IRGRP
68\&|
69.Dv S_IWGRP
70\&|
71.Dv S_IROTH
72\&|
73.Dv S_IWOTH Ns \\*q
74.Pq Li 0666 ,
75as modified by the process'
76umask value (see
77.Xr umask 2 ) .
78.Pp
79Files may only be read or written.
80Seek operations are not allowed.
81.Pp
82The
83.Fa bits
84argument, if non-zero, is set to the bits code limit.
85If zero, the default is 16.
86See
87.Xr compress 1
88for more information.
89.Sh RETURN VALUES
90Upon successful completion
91.Fn zopen
92returns a
93.Tn FILE
94pointer.
95Otherwise,
96.Dv NULL
97is returned and the global variable
98.Va errno
99is set to indicate the error.
100.Sh ERRORS
101.Bl -tag -width [EINVAL]
102.It Bq Er EINVAL
103The
104.Fa mode
105or
106.Fa bits
107arguments specified to
108.Fn zopen
109were invalid.
110.It Bq Er EFTYPE
111The compressed file starts with an invalid header, or the compressed
112file is compressed with more bits than can be handled.
113.El
114.Pp
115The
116.Fn zopen
117function may also fail and set
118.Va errno
119for any of the errors specified for the routines
120.Xr fopen 3
121or
122.Xr funopen 3 .
123.Sh SEE ALSO
124.Xr compress 1 ,
125.Xr fopen 3 ,
126.Xr funopen 3
127.Sh HISTORY
128The
129.Nm
130function
131first appeared in
132.Bx 4.4 .
133.Sh BUGS
134The
135.Fn zopen
136function
137may not be portable to systems other than
138.Bx .