sl@0: /* SETVBUF.C
sl@0:  * 
sl@0:  * Portions Copyright (c) 1990-2009 Nokia Corporation and/or its subsidiary(-ies).
sl@0:  * All rights reserved.
sl@0:  */
sl@0: 
sl@0: /*
sl@0:  * Copyright (c) 1990 The Regents of the University of California.
sl@0:  * All rights reserved.
sl@0:  *
sl@0:  * Redistribution and use in source and binary forms are permitted
sl@0:  * provided that the above copyright notice and this paragraph are
sl@0:  * duplicated in all such forms and that any documentation,
sl@0:  * advertising materials, and other materials related to such
sl@0:  * distribution and use acknowledge that the software was developed
sl@0:  * by the University of California, Berkeley.  The name of the
sl@0:  * University may not be used to endorse or promote products derived
sl@0:  * from this software without specific prior written permission.
sl@0:  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
sl@0:  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
sl@0:  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
sl@0:  */
sl@0: 
sl@0: /*
sl@0: FUNCTION
sl@0: <<setvbuf>>---specify file or stream buffering
sl@0: 
sl@0: INDEX
sl@0: 	setvbuf
sl@0: 
sl@0: ANSI_SYNOPSIS
sl@0: 	#include <stdio.h>
sl@0: 	int setvbuf(FILE *<[fp]>, char *<[buf]>,
sl@0: 	            int <[mode]>, size_t <[size]>);
sl@0: 
sl@0: TRAD_SYNOPSIS
sl@0: 	#include <stdio.h>
sl@0: 	int setvbuf(<[fp]>, <[buf]>, <[mode]>, <[size]>)
sl@0: 	FILE *<[fp]>;
sl@0: 	char *<[buf]>;
sl@0: 	int <[mode]>;
sl@0: 	size_t <[size]>;
sl@0: 
sl@0: DESCRIPTION
sl@0: Use <<setvbuf>> to specify what kind of buffering you want for the
sl@0: file or stream identified by <[fp]>, by using one of the following
sl@0: values (from <<stdio.h>>) as the <[mode]> argument:
sl@0: 
sl@0: o+
sl@0: o _IONBF
sl@0: Do not use a buffer: send output directly to the host system for the
sl@0: file or stream identified by <[fp]>.
sl@0: 
sl@0: o _IOFBF
sl@0: Use full output buffering: output will be passed on to the host system
sl@0: only when the buffer is full, or when an input operation intervenes.
sl@0: 
sl@0: o _IOLBF
sl@0: Use line buffering: pass on output to the host system at every
sl@0: newline, as well as when the buffer is full, or when an input
sl@0: operation intervenes.
sl@0: o-
sl@0: 
sl@0: Use the <[size]> argument to specify how large a buffer you wish.  You
sl@0: can supply the buffer itself, if you wish, by passing a pointer to a
sl@0: suitable area of memory as <[buf]>.  Otherwise, you may pass <<NULL>>
sl@0: as the <[buf]> argument, and <<setvbuf>> will allocate the buffer.
sl@0: 
sl@0: WARNINGS
sl@0: You may only use <<setvbuf>> before performing any file operation other
sl@0: than opening the file.
sl@0: 
sl@0: If you supply a non-null <[buf]>, you must ensure that the associated
sl@0: storage continues to be available until you close the stream
sl@0: identified by <[fp]>.
sl@0: 
sl@0: RETURNS
sl@0: A <<0>> result indicates success, <<EOF>> failure (invalid <[mode]> or
sl@0: <[size]> can cause failure).
sl@0: 
sl@0: PORTABILITY
sl@0: Both ANSI C and the System V Interface Definition (Issue 2) require
sl@0: <<setvbuf>>. However, they differ on the meaning of a <<NULL>> buffer
sl@0: pointer: the SVID issue 2 specification says that a <<NULL>> buffer
sl@0: pointer requests unbuffered output.  For maximum portability, avoid
sl@0: <<NULL>> buffer pointers.
sl@0: 
sl@0: Both specifications describe the result on failure only as a
sl@0: nonzero value.
sl@0: 
sl@0: Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
sl@0: <<lseek>>, <<read>>, <<sbrk>>, <<write>>.
sl@0: */
sl@0: 
sl@0: #include <stdio_r.h>
sl@0: #include <stdlib_r.h>
sl@0: #include "LOCAL.H"
sl@0: 
sl@0: /**
sl@0: Change stream buffering.
sl@0: Changes the buffer to be used for I/O operations with the specified stream.
sl@0: Size and mode for the buffer can be specified.
sl@0: This function should be called once the file associated with the stream 
sl@0: has been opened but before any input or output operation has been done.
sl@0: The size of the buffer is specified by the size parameter,
sl@0: and can be any value between 2 and 32767 in bytes, 
sl@0: this value may be rounded down by some system due to specific alignment.
sl@0: buffer can be NULL.
sl@0: @return If the buffer is correctly assigned to the file a 0 value is returned.
sl@0: On error, a non-zero value is returned. This can be because an invalid type or size has been specified or because an error allocating memory (if NULL buffer was specified).
sl@0: @param fp pointer to an open file. 
sl@0: @param buf User allocated buffer. Must have at least a size of size bytes. 
sl@0: @param mode Specifies a mode for file buffering
sl@0: @param Buffer size in bytes, must be more than 0 and less than 32768, this value may be rounded down by some systems due to specific alignment, in which case the minimum value should be 2.
sl@0: */
sl@0: EXPORT_C int
sl@0: setvbuf (FILE * fp, char *buf, int mode, size_t size)
sl@0: {
sl@0:   int ret = 0;
sl@0:   CHECK_INIT (fp);
sl@0: 
sl@0:   /*
sl@0:    * Verify arguments.  The `int' limit on `size' is due to this
sl@0:    * particular implementation.
sl@0:    */
sl@0: 
sl@0:   if ((mode != _IOFBF && mode != _IOLBF && mode != _IONBF) || (int) size < 0)
sl@0:     return (EOF);
sl@0: 
sl@0:   /*
sl@0:    * Write current buffer, if any; drop read count, if any.
sl@0:    * Make sure putc() will not think fp is line buffered.
sl@0:    * Free old buffer if it was from malloc().  Clear line and
sl@0:    * non buffer flags, and clear malloc flag.
sl@0:    */
sl@0: 
sl@0:   (void) fflush (fp);
sl@0:   fp->_r = 0;
sl@0:   fp->_lbfsize = 0;
sl@0:   if (fp->_flags & __SMBF)
sl@0:     _free_r (fp->_data, (void *) fp->_bf._base);
sl@0:   fp->_flags &= ~(__SLBF | __SNBF | __SMBF);
sl@0: 
sl@0:   if (mode == _IONBF)
sl@0:     goto nbf;
sl@0: 
sl@0:   /*
sl@0:    * Allocate buffer if needed. */
sl@0:   if (buf == NULL)
sl@0:     {
sl@0:       if ((buf = (char *)malloc (size)) == NULL)
sl@0: 	{
sl@0: 	  ret = EOF;
sl@0: 	  /* Try another size... */
sl@0: 	  buf = (char *)malloc (BUFSIZ);
sl@0: 	}
sl@0:       if (buf == NULL)
sl@0: 	{
sl@0: 	  /* Can't allocate it, let's try another approach */
sl@0: nbf:
sl@0: 	  fp->_flags |= __SNBF;
sl@0: 	  fp->_w = 0;
sl@0: 	  fp->_bf._base = fp->_p = fp->_nbuf;
sl@0: 	  fp->_bf._size = 1;
sl@0: 	  return (ret);
sl@0: 	}
sl@0:       fp->_flags |= __SMBF;
sl@0:     }
sl@0:   /*
sl@0:    * Now put back whichever flag is needed, and fix _lbfsize
sl@0:    * if line buffered.  Ensure output flush on exit if the
sl@0:    * stream will be buffered at all.
sl@0:    * Force the buffer to be flushed and hence malloced on first use
sl@0:    */
sl@0: 
sl@0:   switch (mode)
sl@0:     {
sl@0:     case _IOLBF:
sl@0:       fp->_flags |= __SLBF;
sl@0:       fp->_lbfsize = -(int)size;
sl@0:       /* FALLTHROUGH */
sl@0: 
sl@0:     case _IOFBF:
sl@0:       /* no flag */
sl@0:       fp->_data->__cleanup = _cleanup_r;
sl@0:       fp->_bf._base = fp->_p = (unsigned char *) buf;
sl@0:       fp->_bf._size = size;
sl@0:       break;
sl@0:     }
sl@0: 
sl@0:   /*
sl@0:    * Patch up write count if necessary.
sl@0:    */
sl@0: 
sl@0:   if (fp->_flags & __SWR)
sl@0:     fp->_w = fp->_flags & (__SLBF | __SNBF) ? 0 : size;
sl@0: 
sl@0:   return 0;
sl@0: }