BSD 4_3_Net_2 release

[unix-history] / usr / src / lib / libc / stdio / setbuf.3

diff --git a/usr/src/lib/libc/stdio/setbuf.3 b/usr/src/lib/libc/stdio/setbuf.3
index c11bd1d..618d910 100644 (file)
--- a/usr/src/lib/libc/stdio/setbuf.3
+++ b/usr/src/lib/libc/stdio/setbuf.3
@@ -1,142 +1,177 @@
-.\" Copyright (c) 1980 Regents of the University of California.
-.\" All rights reserved.  The Berkeley software License Agreement
-.\" specifies the terms and conditions for redistribution.
+.\" Copyright (c) 1980, 1991 Regents of the University of California.
+.\" All rights reserved.

 .\"
 .\"

-.\"    @(#)setbuf.3    6.4 (Berkeley) 4/1/89
+.\" This code is derived from software contributed to Berkeley by
+.\" the American National Standards Committee X3, on Information
+.\" Processing Systems.

 .\"
 .\"

-.TH SETBUF 3  "April 1, 1989"
-.UC 4
-.SH NAME
-setbuf, setbuffer, setlinebuf \- assign buffering to a stream
-.SH SYNOPSIS
-.B #include <stdio.h>
-.PP
-.B setbuf(stream, buf)
-.br
-.SM
-.B FILE
-.B *stream;
-.br
-.B char *buf;
-.PP
-.B setbuffer(stream, buf, size)
-.br
-.SM
-.B FILE
-.B *stream;
-.br
-.B char *buf;
-.br
-.B int size;
-.PP
-.B setlinebuf(stream)
-.br
-.SM
-.B FILE
-.B *stream;
-.SH DESCRIPTION
+.\" 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.
+.\" 3. All advertising materials mentioning features or use of this software
+.\"    must display the following acknowledgement:
+.\"    This product includes software developed by the University of
+.\"    California, Berkeley and its contributors.
+.\" 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.
+.\"
+.\"     @(#)setbuf.3   6.10 (Berkeley) 6/29/91
+.\"
+.Dd June 29, 1991
+.Dt SETBUF 3
+.Os BSD 4
+.Sh NAME
+.Nm setbuf ,
+.Nm setbuffer ,
+.Nm setlinebuf ,
+.Nm setvbuf
+.Nd stream buffering operations
+.Sh SYNOPSIS
+.Fd #include <stdio.h>
+.Ft int
+.Fn setbuf "FILE *stream" "char *buf"
+.Ft int
+.Fn setbuffer "FILE *stream" "char *buf" "size_t size"
+.Ft int
+.Fn setlinebuf "FILE *stream"
+.Ft int
+.Fn setvbuf "FILE *stream" "char *buf" "int mode" "size_t size"
+.Sh DESCRIPTION

 The three types of buffering available are unbuffered, block buffered,
 and line buffered.
 When an output stream is unbuffered, information appears on the
 destination file or terminal as soon as written;
 when it is block buffered many characters are saved up and written as a block;
 when it is line buffered characters are saved up until a newline is
 The three types of buffering available are unbuffered, block buffered,
 and line buffered.
 When an output stream is unbuffered, information appears on the
 destination file or terminal as soon as written;
 when it is block buffered many characters are saved up and written as a block;
 when it is line buffered characters are saved up until a newline is

-encountered or input is read from stdin.
-.I Fflush
-(see 
-.IR fclose (3))
+output or input is read from any stream attached to a terminal device
+(typically stdin).
+The function
+.Xr fflush 3

 may be used to force the block out early.
 may be used to force the block out early.

+(See 
+.Xr fclose 3 . )

 Normally all files are block buffered.
 Normally all files are block buffered.

-A buffer is obtained from
-.IR  malloc (3)
-upon the first
-.I getc
-or
-.IR  putc (3)
-on the file.
-If the standard stream
-.B stdout
-refers to a terminal it is line buffered.
-The standard stream
-.B stderr
+When the first
+.Tn I/O
+operation occurs on a file,
+.Xr malloc 3
+is called,
+and a buffer is obtained.
+If a stream refers to a terminal
+(as
+.Em stdout
+normally does) it is line buffered.
+The standard error stream
+.Em stderr

 is always unbuffered.
 is always unbuffered.

-.PP
-.I Setbuf
-is used after a stream has been opened but before it is read or written.
-The character array
-.I buf
-is used instead of an automatically allocated buffer.  If
-.I buf
-is the constant pointer
-.SM
-.B NULL,
-input/output will be completely unbuffered.
-A manifest constant 
-.SM
-.B BUFSIZ
-tells how big an array is needed:
-.IP
-.B char
-buf[BUFSIZ];
-.PP
-.IR Setbuffer ,
-an alternate form of 
-.IR setbuf ,
-is used after a stream has been opened but before it is read or written.
-The character array
-.I buf
-whose size is determined by the 
-.I size
-argument is used instead of an automatically allocated buffer.  If
-.I buf
-is the constant pointer
-.SM
-.BR NULL ,
-input/output will be completely unbuffered.
-.PP
-.I Setlinebuf
-is used to change
-.I stdout
-or
-.I stderr
-from block buffered or unbuffered to line buffered.
-Unlike
-.I setbuf
+.Pp
+The
+.Fn setvbuf
+function
+may be used at any time on any open stream
+to change its buffer.
+The
+.Fa mode
+parameter must be one of the following three macros:
+.Bl -tag -width _IOFBF -offset indent
+.It Dv _IONBF
+unbuffered
+.It Dv _IOLBF
+line buffered
+.It Dv _IOFBF
+fully buffered
+.El
+.Pp
+Except for unbuffered files, the 
+.Fa buf
+argument should point to a buffer at least
+.Fa size
+bytes long;
+this buffer will be used instead of the current buffer.
+If the argument
+.Fa buf
+is NULL,
+only the mode is affected;
+a new buffer will be allocated on the next read or write operation.
+The
+.Fn setvbuf
+function
+may be used at any time,
+but can only change the mode of a stream
+when it is not ``active'':
+that is, before any
+.Tn I/O ,
+or immediately after a call to
+.Xr fflush .
+.Pp
+The other three calls are, in effect, simply aliases
+for calls to
+.Fn setvbuf .
+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 .
+The
+.Fn setlinebuf
+function
+is exactly equivalent to the call:
+.Pp
+.Dl setvbuf(stream, (char *)NULL, _IOLBF, 0);
+.Sh SEE ALSO
+.Xr fopen 3 ,
+.Xr fclose 3 ,
+.Xr fread 3 ,
+.Xr malloc 3 ,
+.Xr puts 3 ,
+.Xr printf 3
+.Sh STANDARDS
+The
+.Fn setbuf

 and
 and

-.I setbuffer
-it can be used at any time that the file descriptor is active.
-.PP
-A file can be changed from unbuffered or line buffered to block buffered
-by using
-.I freopen
-(see
-.IR fopen (3)).
-A file can be changed from block buffered or line buffered to unbuffered
-by using
-.I freopen
-followed by
-.I setbuf
-with a buffer argument of 
-.SM
-.BR NULL .
-.SH "SEE ALSO"
-fopen(3),
-getc(3),
-putc(3),
-malloc(3),
-fclose(3),
-puts(3),
-printf(3),
-fread(3)
-.SH BUGS
+.Fn setvbuf
+functions
+conform to
+.St -ansiC .
+.Sh BUGS

 The
 The

-.I setbuffer
+.Fn setbuffer
+and
+.Fn setlinebuf
+functions are not portable to versions of
+.Bx
+before
+.Bx 4.2 .
+On
+.Bx 4.2

 and
 and

-.I setlinebuf
-functions are not portable to non-4.2BSD versions of UNIX.
-On 4.2BSD and 4.3BSD systems,
-.I setbuf
+.Bx 4.3
+systems,
+.Fn setbuf

 always uses a suboptimal buffer size and should be avoided.
 always uses a suboptimal buffer size and should be avoided.

-.I Setbuffer
-is not usually needed
-as the default file I/O buffer sizes are optimal.