file_cmds-46.tar.gz

[apple/file_cmds.git] / compress / zopen.3

.\"	$NetBSD: zopen.3,v 1.4 1998/02/06 06:17:43 perry Exp $
.\"
.\" Copyright (c) 1992, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	@(#)zopen.3	8.1 (Berkeley) 6/9/93
.\"
.Dd June 9, 1993
.Dt ZOPEN 3
.Os
.Sh NAME
.Nm zopen
.Nd compressed stream open function
.Sh SYNOPSIS
.Fd #include <stdio.h>
.Ft FILE *
.Fn zopen "const char *path" "const char *mode" "int bits"
.Sh DESCRIPTION
The
.Fn zopen
function
opens the compressed file whose name is the string pointed to by
.Fa path
and associates a stream with it.
.Pp
The argument
.Fa mode
points to one of the following one-character strings:
.Bl -tag -width indent
.It Dq Li r
Open compressed file for reading.
The stream is positioned at the beginning of the file.
.It Dq Li w
Truncate file to zero length or create compressed file for writing.
The stream is positioned at the beginning of the file.
.El
.Pp
Any created files will have mode
.Pf \\*q Dv S_IRUSR
\&|
.Dv S_IWUSR
\&|
.Dv S_IRGRP
\&|
.Dv S_IWGRP
\&|
.Dv S_IROTH
\&|
.Dv S_IWOTH Ns \\*q
.Pq Li 0666 ,
as modified by the process'
umask value (see
.Xr umask 2 ) .
.Pp
Files may only be read or written.
Seek operations are not allowed.
.Pp
The
.Fa bits
argument, if non-zero, is set to the bits code limit.
If zero, the default is 16.
See
.Fn compress 1
for more information.
.Sh RETURN VALUES
Upon successful completion
.Fn zopen
returns a
.Tn FILE
pointer.
Otherwise,
.Dv NULL
is returned and the global variable
.Va errno
is set to indicate the error.
.Sh ERRORS
.Bl -tag -width [EINVAL]
.It Bq Er EINVAL
The
.Fa mode
or
.Fa bits
arguments specified to
.Fn zopen
were invalid.
.It Bq Er EFTYPE
The compressed file starts with an invalid header, or the compressed
file is compressed with more bits than can be handled.
.El
.Pp
The
.Fn zopen
function may also fail and set
.Va errno
for any of the errors specified for the routines
.Xr fopen 3
or
.Xr funopen 3 .
.Sh SEE ALSO
.Xr compress 1 ,
.Xr fopen 3 ,
.Xr funopen 3
.Sh HISTORY
The
.Nm zopen
function
first appeared in
.Bx 4.4 .
.Sh BUGS
The
.Fn zopen
function
may not be portable to systems other than
.Bx .