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/*
* Copyright (c) 1990 The Regents of the University of California.
* All rights reserved.
*
* Redistribution and use in source and binary forms are permitted
* provided that the above copyright notice and this paragraph are
* duplicated in all such forms and that any documentation,
* advertising materials, and other materials related to such
* distribution and use acknowledge that the software was developed
* by the University of California, Berkeley. The name of the
* University may not be used to endorse or promote products derived
* from this software without specific prior written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/
/*
FUNCTION
<<setvbuf>>---specify file or stream buffering
INDEX
setvbuf
ANSI_SYNOPSIS
#include <stdio.h>
int setvbuf(FILE *<[fp]>, char *<[buf]>,
int <[mode]>, size_t <[size]>);
TRAD_SYNOPSIS
#include <stdio.h>
int setvbuf(<[fp]>, <[buf]>, <[mode]>, <[size]>)
FILE *<[fp]>;
char *<[buf]>;
int <[mode]>;
size_t <[size]>;
DESCRIPTION
Use <<setvbuf>> to specify what kind of buffering you want for the
file or stream identified by <[fp]>, by using one of the following
values (from <<stdio.h>>) as the <[mode]> argument:
o+
o _IONBF
Do not use a buffer: send output directly to the host system for the
file or stream identified by <[fp]>.
o _IOFBF
Use full output buffering: output will be passed on to the host system
only when the buffer is full, or when an input operation intervenes.
o _IOLBF
Use line buffering: pass on output to the host system at every
newline, as well as when the buffer is full, or when an input
operation intervenes.
o-
Use the <[size]> argument to specify how large a buffer you wish. You
can supply the buffer itself, if you wish, by passing a pointer to a
suitable area of memory as <[buf]>. Otherwise, you may pass <<NULL>>
as the <[buf]> argument, and <<setvbuf>> will allocate the buffer.
WARNINGS
You may only use <<setvbuf>> before performing any file operation other
than opening the file.
If you supply a non-null <[buf]>, you must ensure that the associated
storage continues to be available until you close the stream
identified by <[fp]>.
RETURNS
A <<0>> result indicates success, <<EOF>> failure (invalid <[mode]> or
<[size]> can cause failure).
PORTABILITY
Both ANSI C and the System V Interface Definition (Issue 2) require
<<setvbuf>>. However, they differ on the meaning of a <<NULL>> buffer
pointer: the SVID issue 2 specification says that a <<NULL>> buffer
pointer requests unbuffered output. For maximum portability, avoid
<<NULL>> buffer pointers.
Both specifications describe the result on failure only as a
nonzero value.
Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
<<lseek>>, <<read>>, <<sbrk>>, <<write>>.
*/
#include <_ansi.h>
#include <stdio.h>
#include <stdlib.h>
#include "local.h"
/*
* Set one of the three kinds of buffering, optionally including a buffer.
*/
int
_DEFUN (setvbuf, (fp, buf, mode, size),
register FILE * fp _AND
char *buf _AND
register int mode _AND
register size_t size)
{
int ret = 0;
_flockfile(fp);
CHECK_INIT (fp);
/*
* Verify arguments. The `int' limit on `size' is due to this
* particular implementation.
*/
if ((mode != _IOFBF && mode != _IOLBF && mode != _IONBF) || (int)(_POINTER_INT) size < 0)
{
_funlockfile(fp);
return (EOF);
}
/*
* Write current buffer, if any; drop read count, if any.
* Make sure putc() will not think fp is line buffered.
* Free old buffer if it was from malloc(). Clear line and
* non buffer flags, and clear malloc flag.
*/
(void) fflush (fp);
fp->_r = 0;
fp->_lbfsize = 0;
if (fp->_flags & __SMBF)
_free_r (fp->_data, (void *) fp->_bf._base);
fp->_flags &= ~(__SLBF | __SNBF | __SMBF);
if (mode == _IONBF)
goto nbf;
/*
* Allocate buffer if needed. */
if (buf == NULL)
{
/* we need this here because malloc() may return a pointer
even if size == 0 */
if (!size) size = BUFSIZ;
if ((buf = malloc (size)) == NULL)
{
ret = EOF;
/* Try another size... */
buf = malloc (BUFSIZ);
size = BUFSIZ;
}
if (buf == NULL)
{
/* Can't allocate it, let's try another approach */
nbf:
fp->_flags |= __SNBF;
fp->_w = 0;
fp->_bf._base = fp->_p = fp->_nbuf;
fp->_bf._size = 1;
_funlockfile(fp);
return (ret);
}
fp->_flags |= __SMBF;
}
/*
* Now put back whichever flag is needed, and fix _lbfsize
* if line buffered. Ensure output flush on exit if the
* stream will be buffered at all.
* If buf is NULL then make _lbfsize 0 to force the buffer
* to be flushed and hence malloced on first use
*/
switch (mode)
{
case _IOLBF:
fp->_flags |= __SLBF;
fp->_lbfsize = buf ? -size : 0;
/* FALLTHROUGH */
case _IOFBF:
/* no flag */
fp->_data->__cleanup = _cleanup_r;
fp->_bf._base = fp->_p = (unsigned char *) buf;
fp->_bf._size = size;
break;
}
/*
* Patch up write count if necessary.
*/
if (fp->_flags & __SWR)
fp->_w = fp->_flags & (__SLBF | __SNBF) ? 0 : size;
_funlockfile(fp);
return 0;
}
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