1 /* Flushing buffers of a FILE stream.
2 Copyright (C) 2007-2023 Free Software Foundation, Inc.
3
4 This file is free software: you can redistribute it and/or modify
5 it under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1 of the
7 License, or (at your option) any later version.
8
9 This file 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
12 GNU Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
16
17 #include <config.h>
18
19 /* Specification. */
20 #include <stdio.h>
21
22 #if HAVE___FPURGE /* glibc >= 2.2, Haiku, Solaris >= 7, UnixWare >= 7.1.4.MP4, Cygwin >= 1.7.10, Android API >= 23, musl libc */
23 # if HAVE_STDIO_EXT_H
24 # include <stdio_ext.h>
25 # endif
26 #endif
27 #include <stdlib.h>
28
29 #include "stdio-impl.h"
30
31 int
32 fpurge (FILE *fp)
33 {
34 #if HAVE___FPURGE /* glibc >= 2.2, Haiku, Solaris >= 7, UnixWare >= 7.1.4.MP4, Cygwin >= 1.7.10, Android API >= 23, musl libc */
35
36 __fpurge (fp);
37 /* The __fpurge function does not have a return value. */
38 return 0;
39
40 #elif HAVE_FPURGE /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin >= 1.7 */
41
42 /* Call the system's fpurge function. */
43 # undef fpurge
44 # if !HAVE_DECL_FPURGE
45 extern int fpurge (FILE *);
46 # endif
47 int result = fpurge (fp);
48 # if defined __sferror || defined __DragonFly__ || defined __ANDROID__
49 /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
50 if (result == 0)
51 /* Correct the invariants that fpurge broke.
52 <stdio.h> on BSD systems says:
53 "The following always hold: if _flags & __SRD, _w is 0."
54 If this invariant is not fulfilled and the stream is read-write but
55 currently reading, subsequent putc or fputc calls will write directly
56 into the buffer, although they shouldn't be allowed to. */
57 if ((fp_->_flags & __SRD) != 0)
58 fp_->_w = 0;
59 # endif
60 return result;
61
62 #else
63
64 /* Most systems provide FILE as a struct and the necessary bitmask in
65 <stdio.h>, because they need it for implementing getc() and putc() as
66 fast macros. */
67 # if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
68 /* GNU libc, BeOS, Haiku, Linux libc5 */
69 fp->_IO_read_end = fp->_IO_read_ptr;
70 fp->_IO_write_ptr = fp->_IO_write_base;
71 /* Avoid memory leak when there is an active ungetc buffer. */
72 if (fp->_IO_save_base != NULL)
73 {
74 free (fp->_IO_save_base);
75 fp->_IO_save_base = NULL;
76 }
77 return 0;
78 # elif defined __sferror || defined __DragonFly__ || defined __ANDROID__
79 /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
80 fp_->_p = fp_->_bf._base;
81 fp_->_r = 0;
82 fp_->_w = ((fp_->_flags & (__SLBF | __SNBF | __SRD)) == 0 /* fully buffered and not currently reading? */
83 ? fp_->_bf._size
84 : 0);
85 /* Avoid memory leak when there is an active ungetc buffer. */
86 if (fp_ub._base != NULL)
87 {
88 if (fp_ub._base != fp_->_ubuf)
89 free (fp_ub._base);
90 fp_ub._base = NULL;
91 }
92 return 0;
93 # elif defined __EMX__ /* emx+gcc */
94 fp->_ptr = fp->_buffer;
95 fp->_rcount = 0;
96 fp->_wcount = 0;
97 fp->_ungetc_count = 0;
98 return 0;
99 # elif defined __minix /* Minix */
100 fp->_ptr = fp->_buf;
101 if (fp->_ptr != NULL)
102 fp->_count = 0;
103 return 0;
104 # elif defined _IOERR /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, UnixWare, mingw, MSVC, NonStop Kernel, OpenVMS */
105 fp_->_ptr = fp_->_base;
106 if (fp_->_ptr != NULL)
107 fp_->_cnt = 0;
108 return 0;
109 # elif defined __UCLIBC__ /* uClibc */
110 # ifdef __STDIO_BUFFERS
111 if (fp->__modeflags & __FLAG_WRITING)
112 fp->__bufpos = fp->__bufstart;
113 else if (fp->__modeflags & (__FLAG_READONLY | __FLAG_READING))
114 fp->__bufpos = fp->__bufread;
115 # endif
116 return 0;
117 # elif defined __QNX__ /* QNX */
118 fp->_Rback = fp->_Back + sizeof (fp->_Back);
119 fp->_Rsave = NULL;
120 if (fp->_Mode & 0x2000 /* _MWRITE */)
121 /* fp->_Buf <= fp->_Next <= fp->_Wend */
122 fp->_Next = fp->_Buf;
123 else
124 /* fp->_Buf <= fp->_Next <= fp->_Rend */
125 fp->_Rend = fp->_Next;
126 return 0;
127 # elif defined __MINT__ /* Atari FreeMiNT */
128 if (fp->__pushed_back)
129 {
130 fp->__bufp = fp->__pushback_bufp;
131 fp->__pushed_back = 0;
132 }
133 /* Preserve the current file position. */
134 if (fp->__target != -1)
135 fp->__target += fp->__bufp - fp->__buffer;
136 fp->__bufp = fp->__buffer;
137 /* Nothing in the buffer, next getc is nontrivial. */
138 fp->__get_limit = fp->__bufp;
139 /* Nothing in the buffer, next putc is nontrivial. */
140 fp->__put_limit = fp->__buffer;
141 return 0;
142 # elif defined EPLAN9 /* Plan9 */
143 fp->rp = fp->wp = fp->lp = fp->buf;
144 return 0;
145 # else
146 # 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."
147 # endif
148
149 #endif
150 }