1/* Copyright (C) 1993, 1996, 1997 Free Software Foundation, Inc.
2   This file is part of the GNU IO Library.
3
4   This library is free software; you can redistribute it and/or
5   modify it under the terms of the GNU General Public License as
6   published by the Free Software Foundation; either version 2, or (at
7   your option) any later version.
8
9   This library is distributed in the hope that it will be useful, but
10   WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   General Public License for more details.
13
14   You should have received a copy of the GNU General Public License
15   along with this library; see the file COPYING.  If not, write to
16   the Free Software Foundation, 59 Temple Place - Suite 330, Boston,
17   MA 02111-1307, USA.
18
19   As a special exception, if you link this library with files
20   compiled with a GNU compiler to produce an executable, this does
21   not cause the resulting executable to be covered by the GNU General
22   Public License.  This exception does not however invalidate any
23   other reasons why the executable file might be covered by the GNU
24   General Public License.  */
25
26#include "libioP.h"
27
28#define _IOFBF 0 /* Fully buffered. */
29#define _IOLBF 1 /* Line buffered. */
30#define _IONBF 2 /* No buffering. */
31
32int
33_IO_setvbuf (fp, buf, mode, size)
34     _IO_FILE *fp;
35     char *buf;
36     int mode;
37     _IO_size_t size;
38{
39  int result;
40  CHECK_FILE (fp, EOF);
41  _IO_cleanup_region_start ((void (*) __P ((void *))) _IO_funlockfile, fp);
42  _IO_flockfile (fp);
43  switch (mode)
44    {
45    case _IOFBF:
46      fp->_IO_file_flags &= ~_IO_LINE_BUF|_IO_UNBUFFERED;
47      if (buf == NULL)
48	{
49	  if (fp->_IO_buf_base == NULL)
50	    {
51	      /* There is no flag to distinguish between "fully buffered
52		 mode has been explicitly set" as opposed to "line
53		 buffering has not been explicitly set".  In both
54		 cases, _IO_LINE_BUF is off.  If this is a tty, and
55		 _IO_filedoalloc later gets called, it cannot know if
56		 it should set the _IO_LINE_BUF flag (because that is
57		 the default), or not (because we have explicitly asked
58		 for fully buffered mode).  So we make sure a buffer
59		 gets allocated now, and explicitly turn off line
60		 buffering.
61
62		 A possibly cleaner alternative would be to add an
63		 extra flag, but then flags are a finite resource.  */
64	      if (_IO_DOALLOCATE (fp) < 0)
65		{
66		  result = EOF;
67		  goto unlock_return;
68		}
69	      fp->_IO_file_flags &= ~_IO_LINE_BUF;
70	    }
71	  result = 0;
72	  goto unlock_return;
73	}
74      break;
75    case _IOLBF:
76      fp->_IO_file_flags &= ~_IO_UNBUFFERED;
77      fp->_IO_file_flags |= _IO_LINE_BUF;
78      if (buf == NULL)
79	{
80	  result = 0;
81	  goto unlock_return;
82	}
83      break;
84    case _IONBF:
85      buf = NULL;
86      size = 0;
87      break;
88    default:
89      result = EOF;
90      goto unlock_return;
91    }
92  result = _IO_SETBUF (fp, buf, size) == NULL ? EOF : 0;
93unlock_return:
94  _IO_cleanup_region_end (1);
95  return result;
96}
97
98#ifdef weak_alias
99weak_alias (_IO_setvbuf, setvbuf)
100#endif
101