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.Dd $Mdocdate: November 25 2014 $
.Dt SETBUF 3
.Os
.Sh NAME
.Nm setbuf ,
.Nm setbuffer ,
.Nm setlinebuf
.Nd stream buffering operations
.Sh SYNOPSIS
.In stdio.h
.Ft void
.Fn setbuf "FILE *stream" "char *buf"
.Ft void
.Fn setbuffer "FILE *stream" "char *buf" "size_t size"
.Ft int
.Fn setlinebuf "FILE *stream"
.Sh DESCRIPTION
.Bf -symbolic
These interfaces are obsoleted by
.Xr setvbuf 3 .
.Ef
.Pp
The
.Fn setbuf ,
.Fn setbuffer ,
and
.Fn setlinebuf
functions are used to modify the buffering of a stream.
These functions are provided for compatibility with legacy code.
New code should use
.Xr setvbuf 3
instead.
.Pp
Except for the lack of a return value, the
.Fn setbuf
function is exactly equivalent to the call
.Pp
.Dl "setvbuf(stream, buf, buf ? _IOFBF : _IONBF, BUFSIZ);"
.Pp
The
.Fn setbuffer
function is the same, except that the size of the buffer is up to the caller,
rather than being determined by the default
.Dv BUFSIZ .
.Pp
The
.Fn setlinebuf
function is exactly equivalent to the call:
.Pp
.Dl "setvbuf(stream, NULL, _IOLBF, 0);"
.Sh RETURN VALUES
Upon successful completion, the
.Fn setlinebuf
function returns 0.
If the request cannot be honored, a non-zero value is returned,
possibly setting
.Va errno
to indicate the error.
The stream is not modified in the error case.
.Sh ERRORS
The
.Fn setbuf ,
.Fn setbuffer ,
and
.Fn setlinebuf
functions will fail if:
.Bl -tag -width Er
.It Bq Er EBADF
The
.Fa stream
specified is not associated with a valid file descriptor.
.El
.Sh SEE ALSO
.Xr fclose 3 ,
.Xr fopen 3 ,
.Xr fread 3 ,
.Xr malloc 3 ,
.Xr printf 3 ,
.Xr puts 3 ,
.Xr setvbuf 3
.Sh STANDARDS
The
.Fn setbuf
function conforms to
.St -isoC-99 .
The
.Fn setbuffer
and
.Fn setlinebuf
functions are non-standard and should not be used if portability is required.
.Sh HISTORY
The
.Fn setbuf
function first appeared in
.At v7 .
The
.Fn setbuffer
function first appeared in
.Bx 4.1c .
The
.Fn setlinebuf
function first appeared in
.Bx 4.2 .
.Sh BUGS
The
.Fn setbuf
function usually uses a suboptimal buffer size and should be avoided.