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[/] [openrisc/] [trunk/] [gnu-stable/] [newlib-1.18.0/] [newlib/] [libc/] [stdio/] [setvbuf.c] - Blame information for rev 829

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1 207 jeremybenn
/*
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 * Copyright (c) 1990 The Regents of the University of California.
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 * All rights reserved.
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 *
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 * Redistribution and use in source and binary forms are permitted
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 * provided that the above copyright notice and this paragraph are
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 * duplicated in all such forms and that any documentation,
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 * advertising materials, and other materials related to such
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 * distribution and use acknowledge that the software was developed
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 * by the University of California, Berkeley.  The name of the
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 * University may not be used to endorse or promote products derived
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 * from this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
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 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
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 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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 */
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/*
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FUNCTION
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<<setvbuf>>---specify file or stream buffering
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INDEX
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        setvbuf
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ANSI_SYNOPSIS
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        #include <stdio.h>
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        int setvbuf(FILE *<[fp]>, char *<[buf]>,
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                    int <[mode]>, size_t <[size]>);
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TRAD_SYNOPSIS
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        #include <stdio.h>
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        int setvbuf(<[fp]>, <[buf]>, <[mode]>, <[size]>)
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        FILE *<[fp]>;
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        char *<[buf]>;
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        int <[mode]>;
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        size_t <[size]>;
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DESCRIPTION
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Use <<setvbuf>> to specify what kind of buffering you want for the
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file or stream identified by <[fp]>, by using one of the following
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values (from <<stdio.h>>) as the <[mode]> argument:
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o+
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o _IONBF
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Do not use a buffer: send output directly to the host system for the
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file or stream identified by <[fp]>.
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o _IOFBF
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Use full output buffering: output will be passed on to the host system
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only when the buffer is full, or when an input operation intervenes.
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o _IOLBF
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Use line buffering: pass on output to the host system at every
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newline, as well as when the buffer is full, or when an input
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operation intervenes.
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o-
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Use the <[size]> argument to specify how large a buffer you wish.  You
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can supply the buffer itself, if you wish, by passing a pointer to a
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suitable area of memory as <[buf]>.  Otherwise, you may pass <<NULL>>
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as the <[buf]> argument, and <<setvbuf>> will allocate the buffer.
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WARNINGS
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You may only use <<setvbuf>> before performing any file operation other
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than opening the file.
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If you supply a non-null <[buf]>, you must ensure that the associated
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storage continues to be available until you close the stream
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identified by <[fp]>.
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RETURNS
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A <<0>> result indicates success, <<EOF>> failure (invalid <[mode]> or
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<[size]> can cause failure).
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PORTABILITY
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Both ANSI C and the System V Interface Definition (Issue 2) require
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<<setvbuf>>. However, they differ on the meaning of a <<NULL>> buffer
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pointer: the SVID issue 2 specification says that a <<NULL>> buffer
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pointer requests unbuffered output.  For maximum portability, avoid
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<<NULL>> buffer pointers.
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Both specifications describe the result on failure only as a
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nonzero value.
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Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
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<<lseek>>, <<read>>, <<sbrk>>, <<write>>.
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*/
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#include <_ansi.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "local.h"
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/*
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 * Set one of the three kinds of buffering, optionally including a buffer.
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 */
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int
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_DEFUN(setvbuf, (fp, buf, mode, size),
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       register FILE * fp _AND
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       char *buf          _AND
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       register int mode  _AND
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       register size_t size)
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{
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  int ret = 0;
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  CHECK_INIT (_REENT, fp);
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  _flockfile (fp);
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  /*
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   * Verify arguments.  The `int' limit on `size' is due to this
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   * particular implementation.
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   */
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  if ((mode != _IOFBF && mode != _IOLBF && mode != _IONBF) || (int)(_POINTER_INT) size < 0)
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    {
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      _funlockfile (fp);
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      return (EOF);
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    }
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  /*
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   * Write current buffer, if any; drop read count, if any.
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   * Make sure putc() will not think fp is line buffered.
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   * Free old buffer if it was from malloc().  Clear line and
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   * non buffer flags, and clear malloc flag.
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   */
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  _fflush_r (_REENT, fp);
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  fp->_r = 0;
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  fp->_lbfsize = 0;
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  if (fp->_flags & __SMBF)
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    _free_r (_REENT, (_PTR) fp->_bf._base);
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  fp->_flags &= ~(__SLBF | __SNBF | __SMBF);
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  if (mode == _IONBF)
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    goto nbf;
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  /*
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   * Allocate buffer if needed. */
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  if (buf == NULL)
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    {
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      /* we need this here because malloc() may return a pointer
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         even if size == 0 */
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      if (!size) size = BUFSIZ;
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      if ((buf = malloc (size)) == NULL)
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        {
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          ret = EOF;
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          /* Try another size... */
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          buf = malloc (BUFSIZ);
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          size = BUFSIZ;
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        }
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      if (buf == NULL)
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        {
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          /* Can't allocate it, let's try another approach */
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nbf:
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          fp->_flags |= __SNBF;
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          fp->_w = 0;
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          fp->_bf._base = fp->_p = fp->_nbuf;
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          fp->_bf._size = 1;
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          _funlockfile (fp);
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          return (ret);
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        }
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      fp->_flags |= __SMBF;
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    }
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  /*
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   * Now put back whichever flag is needed, and fix _lbfsize
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   * if line buffered.  Ensure output flush on exit if the
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   * stream will be buffered at all.
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   * If buf is NULL then make _lbfsize 0 to force the buffer
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   * to be flushed and hence malloced on first use
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   */
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  switch (mode)
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    {
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    case _IOLBF:
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      fp->_flags |= __SLBF;
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      fp->_lbfsize = buf ? -size : 0;
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      /* FALLTHROUGH */
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    case _IOFBF:
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      /* no flag */
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      _REENT->__cleanup = _cleanup_r;
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      fp->_bf._base = fp->_p = (unsigned char *) buf;
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      fp->_bf._size = size;
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      break;
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    }
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  /*
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   * Patch up write count if necessary.
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   */
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  if (fp->_flags & __SWR)
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    fp->_w = fp->_flags & (__SLBF | __SNBF) ? 0 : size;
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  _funlockfile (fp);
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  return 0;
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}

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