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.\" Author: Archie Cobbs <archie@freebsd.org>
.\"
.\" $Id: boundary_fopen.3,v 1.1.1.1 2012/02/21 23:25:53 misho Exp $
.\"
.Dd April 22, 2002
.Dt BOUNDARY_FOPEN 3
.Os
.Sh NAME
.Nm boundary_fopen
.Nd read from a stream until a boundary string is matched
.Sh LIBRARY
PDEL Library (libpdel, \-lpdel)
.Sh SYNOPSIS
.In stdio.h
.In pdel/io/boundary_fp.h
.Ft "FILE *"
.Fn boundary_fopen "FILE *fp" "const char *boundary" "int closeit"
.Sh DESCRIPTION
.Fn boundary_fopen
creates a new read-only stream that reads data from the underlying stream
.Fa fp
until the
.Fa boundary
string is encountered, after which
.Dv EOF
is returned.
If the boundary string does not appear in the underlying stream input,
the entire input is passed through unaltered.
.Pp
When the boundary string appears, the last character readable from the
newly created boundary stream will be the character just before the first
character of the boundary string. 
Therefore, the boundary string itself does not appear in the input
from the boundary stream.
In no case are any characters beyond the last character of the boundary
string read out from the underlying stream, i.e.,
the last character read from the underlying stream will be
the last character of the boundary string.
.Pp
The boundary matching algorithm runs in linear time.
However, the
.Fa boundary
string is limited to 255 characters in length (not counting the
terminating '\\0' byte).
.Pp
.Xr fclose 3
should be used to close the returned stream.
The
.Fa closeit
parameter determines whether the underlying stream
.Fa fp
is also closed when the boundary stream is closed.
.Pp
Boundary streams are useful for online parsing of multipart
MIME document body parts as defined in RFC 2046.
.Sh RETURN VALUES
.Fn boundary_fopen
returns
.Dv NULL
to indicate an error, with
.Va errno
set appropriately.
.Sh SEE ALSO
.Xr count_fopen 3 ,
.Xr string_fp 3 ,
.Xr libpdel 3
.Rs
.%A N. Freed
.%A N. Borenstein
.%T "Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types"
.%O RFC 2046
.Re
.Sh HISTORY
The PDEL library was developed at Packet Design, LLC.
.Dv "http://www.packetdesign.com/"
.Sh AUTHORS
.An Archie Cobbs Aq archie@freebsd.org