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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,
* and/or 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
SYNOPSIS
#include <stdio.h>
int setvbuf(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
setvbuf (register FILE * fp,
char *buf,
register int mode,
register size_t size)
{
int ret = 0;
struct _reent *reent = _REENT;
size_t iosize;
int ttyflag;
CHECK_INIT (reent, fp);
/*
* Verify arguments. The `int' limit on `size' is due to this
* particular implementation. Note, buf and size are ignored
* when setting _IONBF.
*/
if (mode != _IONBF)
if ((mode != _IOFBF && mode != _IOLBF) || (int)(_POINTER_INT) size < 0)
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.
*/
_newlib_flockfile_start (fp);
_fflush_r (reent, fp);
if (HASUB(fp))
FREEUB(reent, fp);
fp->_r = fp->_lbfsize = 0;
if (fp->_flags & __SMBF)
_free_r (reent, (void *) fp->_bf._base);
fp->_flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF);
if (mode == _IONBF)
goto nbf;
/*
* Find optimal I/O size for seek optimization. This also returns
* a `tty flag' to suggest that we check isatty(fd), but we do not
* care since our caller told us how to buffer.
*/
fp->_flags |= __swhatbuf_r (reent, fp, &iosize, &ttyflag);
if (size == 0)
{
buf = NULL;
size = iosize;
}
/* Allocate buffer if needed. */
if (buf == NULL)
{
if ((buf = malloc (size)) == NULL)
{
/*
* Unable to honor user's request. We will return
* failure, but try again with file system size.
*/
ret = EOF;
if (size != iosize)
{
size = iosize;
buf = malloc (size);
}
}
if (buf == NULL)
{
/* No luck; switch to unbuffered I/O. */
nbf:
fp->_flags |= __SNBF;
fp->_w = 0;
fp->_bf._base = fp->_p = fp->_nbuf;
fp->_bf._size = 1;
_newlib_flockfile_exit (fp);
return (ret);
}
fp->_flags |= __SMBF;
}
/*
* We're committed to buffering from here, so make sure we've
* registered to flush buffers on exit.
*/
if (!reent->__sdidinit)
__sinit(reent);
#ifdef _FSEEK_OPTIMIZATION
/*
* Kill any seek optimization if the buffer is not the
* right size.
*
* SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
*/
if (size != iosize)
fp->_flags |= __SNPT;
#endif
/*
* Fix up the FILE fields, and set __cleanup for output flush on
* exit (since we are buffered in some way).
*/
if (mode == _IOLBF)
fp->_flags |= __SLBF;
fp->_bf._base = fp->_p = (unsigned char *) buf;
fp->_bf._size = size;
/* fp->_lbfsize is still 0 */
if (fp->_flags & __SWR)
{
/*
* Begin or continue writing: see __swsetup(). Note
* that __SNBF is impossible (it was handled earlier).
*/
if (fp->_flags & __SLBF)
{
fp->_w = 0;
fp->_lbfsize = -fp->_bf._size;
}
else
fp->_w = size;
}
else
{
/* begin/continue reading, or stay in intermediate state */
fp->_w = 0;
}
_newlib_flockfile_end (fp);
return 0;
}
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