1/* Copyright (C) 1993,96,97,98,99,2000,2001,2002 Free Software Foundation, Inc.
2   This file is part of the GNU C Library.
3
4   The GNU C Library is free software; you can redistribute it and/or
5   modify it under the terms of the GNU Lesser General Public
6   License as published by the Free Software Foundation; either
7   version 2.1 of the License, or (at your option) any later version.
8
9   The GNU C Library is distributed in the hope that it will be useful,
10   but WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   Lesser General Public License for more details.
13
14   You should have received a copy of the GNU Lesser General Public
15   License along with the GNU C Library; if not, write to the Free
16   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
17   02111-1307 USA.
18
19   As a special exception, if you link the code in this file with
20   files compiled with a GNU compiler to produce an executable,
21   that does not cause the resulting executable to be covered by
22   the GNU Lesser General Public License.  This exception does not
23   however invalidate any other reasons why the executable file
24   might be covered by the GNU Lesser General Public License.
25   This exception applies to code released by its copyright holders
26   in files containing the exception.  */
27
28#include "libioP.h"
29
30#define _IOFBF 0 /* Fully buffered. */
31#define _IOLBF 1 /* Line buffered. */
32#define _IONBF 2 /* No buffering. */
33
34int
35_IO_setvbuf (fp, buf, mode, size)
36     _IO_FILE *fp;
37     char *buf;
38     int mode;
39     _IO_size_t size;
40{
41  int result;
42  CHECK_FILE (fp, EOF);
43  _IO_cleanup_region_start ((void (*) (void *)) _IO_funlockfile, fp);
44  _IO_flockfile (fp);
45  switch (mode)
46    {
47    case _IOFBF:
48      fp->_IO_file_flags &= ~_IO_LINE_BUF|_IO_UNBUFFERED;
49      if (buf == NULL)
50	{
51	  if (fp->_IO_buf_base == NULL)
52	    {
53	      /* There is no flag to distinguish between "fully buffered
54		 mode has been explicitly set" as opposed to "line
55		 buffering has not been explicitly set".  In both
56		 cases, _IO_LINE_BUF is off.  If this is a tty, and
57		 _IO_filedoalloc later gets called, it cannot know if
58		 it should set the _IO_LINE_BUF flag (because that is
59		 the default), or not (because we have explicitly asked
60		 for fully buffered mode).  So we make sure a buffer
61		 gets allocated now, and explicitly turn off line
62		 buffering.
63
64		 A possibly cleaner alternative would be to add an
65		 extra flag, but then flags are a finite resource.  */
66	      if (_IO_DOALLOCATE (fp) < 0)
67		{
68		  result = EOF;
69		  goto unlock_return;
70		}
71	      fp->_IO_file_flags &= ~_IO_LINE_BUF;
72	    }
73	  result = 0;
74	  goto unlock_return;
75	}
76      break;
77    case _IOLBF:
78      fp->_IO_file_flags &= ~_IO_UNBUFFERED;
79      fp->_IO_file_flags |= _IO_LINE_BUF;
80      if (buf == NULL)
81	{
82	  result = 0;
83	  goto unlock_return;
84	}
85      break;
86    case _IONBF:
87      fp->_IO_file_flags &= ~_IO_LINE_BUF;
88      fp->_IO_file_flags |= _IO_UNBUFFERED;
89      buf = NULL;
90      size = 0;
91      break;
92    default:
93      result = EOF;
94      goto unlock_return;
95    }
96  result = _IO_SETBUF (fp, buf, size) == NULL ? EOF : 0;
97
98unlock_return:
99  _IO_funlockfile (fp);
100  _IO_cleanup_region_end (0);
101  return result;
102}
103INTDEF(_IO_setvbuf)
104
105#ifdef weak_alias
106weak_alias (_IO_setvbuf, setvbuf)
107#endif
108