.\"	$OpenBSD: fparseln.3,v 1.11 2023/01/04 13:00:11 jsg Exp $
.\"	$NetBSD: fparseln.3,v 1.7 1999/07/02 15:49:12 simonb Exp $
.\"
.\" Copyright (c) 1997 Christos Zoulas.  All rights reserved.
.\"
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.Dd $Mdocdate: January 4 2023 $
.Dt FPARSELN 3
.Os
.Sh NAME
.Nm fparseln
.Nd return the next logical line from a stream
.Sh SYNOPSIS
.In stdio.h
.In util.h
.Ft "char *"
.Fo fparseln
.Fa "FILE *stream" "size_t *len" "size_t *lineno"
.Fa "const char delim[3]" "int flags"
.Fc
.Sh DESCRIPTION
The
.Fn fparseln
function
returns a pointer to the next logical line from the stream referenced by
.Fa stream .
This string is null terminated, contains no trailing newline,
and is dynamically allocated on each invocation.
It is the responsibility of the caller to free the pointer.
.Pp
By default, if a character is escaped, both it and the preceding escape
character will be present in the returned string.
Various
.Fa flags
alter this behaviour.
.Pp
The meaning of the arguments is as follows:
.Bl -tag -width "lineno"
.It Fa stream
The stream to read from.
.It Fa len
If not
.Dv NULL ,
the length of the string is stored in the memory location referenced by
.Fa len .
.It Fa lineno
If not
.Dv NULL ,
the value of the memory location to which
.Fa lineno
references is incremented by the number of lines actually read from the file.
.It Fa delim
Contains the escape, continuation, and comment characters.
If a character is NUL then processing for that character is disabled.
If
.Dv NULL ,
all characters default to values specified below.
The contents of
.Fa delim
is as follows:
.Bl -tag -width "delim[0]"
.It Fa delim[0]
The escape character, which defaults to
.Ql \e ,
is used to remove any special meaning from the next character.
.It Fa delim[1]
The continuation character, which defaults to
.Ql \e ,
is used to indicate that the next line should be concatenated with the
current one if this character is the last character on the current line
and is not escaped.
.It Fa delim[2]
The comment character, which defaults to
.Ql # ,
if not escaped indicates the beginning of a comment that extends until the
end of the current line.
.El
.It Fa flags
If non-zero, alter the operation of
.Fn fparseln .
The various flags, which may be OR'ed together, are:
.Bl -tag -width "FPARSELN_UNESCCOMM"
.It Dv FPARSELN_UNESCCOMM
Remove escape preceding an escaped comment.
.It Dv FPARSELN_UNESCCONT
Remove escape preceding an escaped continuation.
.It Dv FPARSELN_UNESCESC
Remove escape preceding an escaped escape.
.It Dv FPARSELN_UNESCREST
Remove escape preceding any other character.
.It Dv FPARSELN_UNESCALL
All of the above.
.El
.El
.Sh RETURN VALUES
Upon successful completion a pointer to the parsed line is returned;
otherwise,
.Dv NULL
is returned.
.Pp
Internally, the
.Fn fparseln
function uses
.Xr fgetln 3 ,
so all error conditions that apply to
.Xr fgetln 3
apply to
.Fn fparseln
as well.
In addition
.Fn fparseln
may set
.Va errno
to
.Er ENOMEM
and return
.Dv NULL
if it runs out of memory.
.Sh SEE ALSO
.Xr fgetln 3