177 lines
4.7 KiB
Groff
177 lines
4.7 KiB
Groff
.\" Copyright (c) 1990, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" This code is derived from software contributed to Berkeley by
|
|
.\" Chris Torek.
|
|
.\" 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.
|
|
.\" 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.
|
|
.\"
|
|
.\" @(#)funopen.3 8.1 (Berkeley) 6/9/93
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd March 19, 2004
|
|
.Dt FUNOPEN 3
|
|
.Os
|
|
.Sh NAME
|
|
.Nm funopen ,
|
|
.Nm fropen ,
|
|
.Nm fwopen
|
|
.Nd open a stream
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In stdio.h
|
|
.Ft FILE *
|
|
.Fn funopen "const void *cookie" "int (*readfn)(void *, char *, int)" "int (*writefn)(void *, const char *, int)" "fpos_t (*seekfn)(void *, fpos_t, int)" "int (*closefn)(void *)"
|
|
.Ft FILE *
|
|
.Fn fropen "void *cookie" "int (*readfn)(void *, char *, int)"
|
|
.Ft FILE *
|
|
.Fn fwopen "void *cookie" "int (*writefn)(void *, const char *, int)"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn funopen
|
|
function
|
|
associates a stream with up to four
|
|
.Dq Tn I/O No functions .
|
|
Either
|
|
.Fa readfn
|
|
or
|
|
.Fa writefn
|
|
must be specified;
|
|
the others can be given as an appropriately-typed
|
|
.Dv NULL
|
|
pointer.
|
|
These
|
|
.Tn I/O
|
|
functions will be used to read, write, seek and
|
|
close the new stream.
|
|
.Pp
|
|
In general, omitting a function means that any attempt to perform the
|
|
associated operation on the resulting stream will fail.
|
|
If the close function is omitted, closing the stream will flush
|
|
any buffered output and then succeed.
|
|
.Pp
|
|
The calling conventions of
|
|
.Fa readfn ,
|
|
.Fa writefn ,
|
|
.Fa seekfn
|
|
and
|
|
.Fa closefn
|
|
must match those, respectively, of
|
|
.Xr read 2 ,
|
|
.Xr write 2 ,
|
|
.Xr lseek 2 ,
|
|
and
|
|
.Xr close 2
|
|
with the single exception that they are passed the
|
|
.Fa cookie
|
|
argument specified to
|
|
.Fn funopen
|
|
in place of the traditional file descriptor argument.
|
|
.Pp
|
|
Read and write
|
|
.Tn I/O
|
|
functions are allowed to change the underlying buffer
|
|
on fully buffered or line buffered streams by calling
|
|
.Xr setvbuf 3 .
|
|
They are also not required to completely fill or empty the buffer.
|
|
They are not, however, allowed to change streams from unbuffered to buffered
|
|
or to change the state of the line buffering flag.
|
|
They must also be prepared to have read or write calls occur on buffers other
|
|
than the one most recently specified.
|
|
.Pp
|
|
All user
|
|
.Tn I/O
|
|
functions can report an error by returning \-1.
|
|
Additionally, all of the functions should set the external variable
|
|
.Va errno
|
|
appropriately if an error occurs.
|
|
.Pp
|
|
An error on
|
|
.Fn closefn
|
|
does not keep the stream open.
|
|
.Pp
|
|
As a convenience, the include file
|
|
.In stdio.h
|
|
defines the macros
|
|
.Fn fropen
|
|
and
|
|
.Fn fwopen
|
|
as calls to
|
|
.Fn funopen
|
|
with only a read or write function specified.
|
|
.Sh RETURN VALUES
|
|
Upon successful completion,
|
|
.Fn funopen
|
|
returns a
|
|
.Dv FILE
|
|
pointer.
|
|
Otherwise,
|
|
.Dv NULL
|
|
is returned and the global variable
|
|
.Va errno
|
|
is set to indicate the error.
|
|
.Sh ERRORS
|
|
.Bl -tag -width Er
|
|
.It Bq Er EINVAL
|
|
The
|
|
.Fn funopen
|
|
function
|
|
was called without either a read or write function.
|
|
The
|
|
.Fn funopen
|
|
function
|
|
may also fail and set
|
|
.Va errno
|
|
for any of the errors
|
|
specified for the routine
|
|
.Xr malloc 3 .
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr fcntl 2 ,
|
|
.Xr open 2 ,
|
|
.Xr fclose 3 ,
|
|
.Xr fopen 3 ,
|
|
.Xr fseek 3 ,
|
|
.Xr setbuf 3
|
|
.Sh HISTORY
|
|
The
|
|
.Fn funopen
|
|
functions first appeared in
|
|
.Bx 4.4 .
|
|
.Sh BUGS
|
|
The
|
|
.Fn funopen
|
|
function
|
|
may not be portable to systems other than
|
|
.Bx .
|
|
.Pp
|
|
The
|
|
.Fn funopen
|
|
interface erroneously assumes that
|
|
.Vt fpos_t
|
|
is an integral type; see
|
|
.Xr fseek 3
|
|
for a discussion of this issue.
|