1/* fpurge - Flushing buffers of a FILE stream. */
2
3/* Copyright (C) 2007 Free Software Foundation, Inc.
4
5   This file is part of GNU Bash, the Bourne Again SHell.
6
7   Bash is free software: you can redistribute it and/or modify
8   it under the terms of the GNU General Public License as published by
9   the Free Software Foundation, either version 3 of the License, or
10   (at your option) any later version.
11
12   Bash is distributed in the hope that it will be useful,
13   but WITHOUT ANY WARRANTY; without even the implied warranty of
14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15   GNU General Public License for more details.
16
17   You should have received a copy of the GNU General Public License
18   along with Bash.  If not, see <http://www.gnu.org/licenses/>.
19*/
20
21#include <config.h>
22
23#include "stdc.h"
24
25#include <stdio.h>
26
27/* Specification.  Same as in ../../externs.h.  */
28#define NEED_FPURGE_DECL
29#if HAVE_FPURGE
30#  define fpurge _bash_fpurge
31#endif
32extern int fpurge __P((FILE *stream));
33
34#if HAVE___FPURGE                   /* glibc >= 2.2, Solaris >= 7 */
35# include <stdio_ext.h>
36#endif
37#include <stdlib.h>
38
39int
40fpurge (FILE *fp)
41{
42#if HAVE___FPURGE                   /* glibc >= 2.2, Solaris >= 7 */
43
44  __fpurge (fp);
45  /* The __fpurge function does not have a return value.  */
46  return 0;
47
48#elif HAVE_FPURGE                   /* FreeBSD, NetBSD, OpenBSD, MacOS X */
49
50  /* Call the system's fpurge function.  */
51# undef fpurge
52# if !HAVE_DECL_FPURGE
53  extern int fpurge (FILE *);
54# endif
55  int result = fpurge (fp);
56# if defined __sferror              /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
57  if (result == 0)
58    /* Correct the invariants that fpurge broke.
59       <stdio.h> on BSD systems says:
60         "The following always hold: if _flags & __SRD, _w is 0."
61       If this invariant is not fulfilled and the stream is read-write but
62       currently writing, subsequent putc or fputc calls will write directly
63       into the buffer, although they shouldn't be allowed to.  */
64    if ((fp->_flags & __SRD) != 0)
65      fp->_w = 0;
66# endif
67  return result;
68
69#else
70
71  /* Most systems provide FILE as a struct and the necessary bitmask in
72     <stdio.h>, because they need it for implementing getc() and putc() as
73     fast macros.  */
74# if defined _IO_ferror_unlocked    /* GNU libc, BeOS */
75  fp->_IO_read_end = fp->_IO_read_ptr;
76  fp->_IO_write_ptr = fp->_IO_write_base;
77  /* Avoid memory leak when there is an active ungetc buffer.  */
78  if (fp->_IO_save_base != NULL)
79    {
80      free (fp->_IO_save_base);
81      fp->_IO_save_base = NULL;
82    }
83  return 0;
84# elif defined __sferror            /* FreeBSD, NetBSD, OpenBSD, MacOS X, Cygwin */
85  fp->_p = fp->_bf._base;
86  fp->_r = 0;
87  fp->_w = ((fp->_flags & (__SLBF | __SNBF | __SRD)) == 0 /* fully buffered and not currently reading? */
88	    ? fp->_bf._size
89	    : 0);
90  /* Avoid memory leak when there is an active ungetc buffer.  */
91#  if defined __NetBSD__ || defined __OpenBSD__ /* NetBSD, OpenBSD */
92   /* See <http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/stdio/fileext.h?rev=HEAD&content-type=text/x-cvsweb-markup>
93      and <http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/stdio/fileext.h?rev=HEAD&content-type=text/x-cvsweb-markup> */
94#   define fp_ub ((struct { struct __sbuf _ub; } *) fp->_ext._base)->_ub
95#  else                                         /* FreeBSD, MacOS X, Cygwin */
96#   define fp_ub fp->_ub
97#  endif
98  if (fp_ub._base != NULL)
99    {
100      if (fp_ub._base != fp->_ubuf)
101	free (fp_ub._base);
102      fp_ub._base = NULL;
103    }
104  return 0;
105# elif defined _IOERR               /* AIX, HP-UX, IRIX, OSF/1, Solaris, mingw */
106  fp->_ptr = fp->_base;
107  if (fp->_ptr != NULL)
108    fp->_cnt = 0;
109  return 0;
110# elif defined __UCLIBC__           /* uClibc */
111#  ifdef __STDIO_BUFFERS
112  if (fp->__modeflags & __FLAG_WRITING)
113    fp->__bufpos = fp->__bufstart;
114  else if (fp->__modeflags & (__FLAG_READONLY | __FLAG_READING))
115    fp->__bufpos = fp->__bufread;
116#  endif
117  return 0;
118# else
119 #error "Please port gnulib fpurge.c to your platform! Look at the definitions of fflush, setvbuf and ungetc on your system, then report this to bug-gnulib."
120# endif
121
122#endif
123}
124