getline.3   [plain text]


.\" Copyright (c) 2009 David Schultz <das@FreeBSD.org>
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.\" $FreeBSD: src/lib/libc/stdio/getline.3,v 1.2 2009/04/06 13:50:04 das Exp $
.\"
.Dd March 29, 2009
.Dt GETLINE 3
.Os
.Sh NAME
.Nm getdelim ,
.Nm getline
.Nd get a line from a stream
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdio.h
.Ft ssize_t
.Fn getdelim "char ** restrict linep" "size_t * restrict linecapp" "int delimiter" " FILE * restrict stream"
.Ft ssize_t
.Fn getline "char ** restrict linep" "size_t * restrict linecapp" " FILE * restrict stream"
.Sh DESCRIPTION
The
.Fn getdelim
function reads a line from
.Fa stream ,
delimited by the character
.Fa delimiter .
The
.Fn getline
function is equivalent to
.Fn getdelim
with the newline character as the delimiter.
The delimiter character is included as part of the line, unless
the end of the file is reached.
The caller may provide a pointer to a malloc buffer for the line in
.Fa *linep ,
and the capacity of that buffer in
.Fa *linecapp ;
if
.Fa *linecapp
is 0, then
.Fa *linep
is treated as
.Dv NULL .
These functions may expand the buffer as needed, as if via
.Fn realloc ,
and update
.Fa *linep
and
.Fa *linecapp
accordingly.
.Sh RETURN VALUES
The
.Fn getdelim
and
.Fn getline
functions return the number of characters written, excluding the
terminating
.Dv NULL .
The value \-1 is returned if an error occurs, or if end-of-file is reached.
.Sh EXAMPLES
The following code fragment reads lines from a file and
writes them to standard output.
The
.Fn fwrite
function is used in case the line contains embedded
.Dv NUL
characters.
.Bd -literal -offset indent
char *line = NULL;
size_t linecap = 0;
ssize_t linelen;
while ((linelen = getline(&line, &linecap, fp)) > 0)
	fwrite(line, linelen, 1, stdout);
.Ed
.Sh ERRORS
These functions may fail if:
.Bl -tag -width Er
.It Bq Er EINVAL
Either
.Fa linep
or
.Fa linecapp
is
.Dv NULL .
.It Bq Er EOVERFLOW
No delimiter was found in the first
.Dv SSIZE_MAX
characters.
.El
.Pp
These functions may also fail for any of the errors specified for
.Fn fgets
and
.Fn malloc .
.Sh SEE ALSO
.Xr fgetln 3 ,
.Xr fgets 3 ,
.Xr malloc 3
.Sh STANDARDS
The
.Fn getdelim
and
.Fn getline
functions conform to
.St -p1003.1-2008 .
.Sh HISTORY
These routines first appeared in
.Fx 8.0 .
.Sh BUGS
There are no wide character versions of
.Fn getdelim
or
.Fn getline .