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Diffstat (limited to 'lib/libc/stdio/setbuf.3')
| -rw-r--r-- | lib/libc/stdio/setbuf.3 | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/lib/libc/stdio/setbuf.3 b/lib/libc/stdio/setbuf.3 new file mode 100644 index 000000000000..618d9102034f --- /dev/null +++ b/lib/libc/stdio/setbuf.3 @@ -0,0 +1,177 @@ +.\" Copyright (c) 1980, 1991 Regents of the University of California. +.\" All rights reserved. +.\" +.\" This code is derived from software contributed to Berkeley by +.\" the American National Standards Committee X3, on Information +.\" Processing Systems. +.\" +.\" 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 +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. +(See +.Xr fclose 3 . ) +Normally all files are block buffered. +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. +.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 +.Fn setvbuf +functions +conform to +.St -ansiC . +.Sh BUGS +The +.Fn setbuffer +and +.Fn setlinebuf +functions are not portable to versions of +.Bx +before +.Bx 4.2 . +On +.Bx 4.2 +and +.Bx 4.3 +systems, +.Fn setbuf +always uses a suboptimal buffer size and should be avoided. |