1 /* An fseeko() function that, together with fflush(), is POSIX compliant.
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 /* Get off_t, lseek, _POSIX_VERSION. */
23 #include <unistd.h>
24
25 #include "stdio-impl.h"
26
27 int
28 fseeko (FILE *fp, off_t offset, int whence)
29 #undef fseeko
30 #if !HAVE_FSEEKO
31 # undef fseek
32 # define fseeko fseek
33 #endif
34 #if _GL_WINDOWS_64_BIT_OFF_T
35 # undef fseeko
36 # if HAVE__FSEEKI64 && HAVE_DECL__FSEEKI64 /* msvc, mingw since msvcrt8.0, mingw64 */
37 # define fseeko _fseeki64
38 # else /* mingw before msvcrt8.0 */
39 # define fseeko fseeko64
40 # endif
41 #endif
42 {
43 #if LSEEK_PIPE_BROKEN
44 /* mingw gives bogus answers rather than failure on non-seekable files. */
45 if (lseek (fileno (fp), 0, SEEK_CUR) == -1)
46 return EOF;
47 #endif
48
49 /* These tests are based on fpurge.c. */
50 #if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
51 /* GNU libc, BeOS, Haiku, Linux libc5 */
52 if (fp->_IO_read_end == fp->_IO_read_ptr
53 && fp->_IO_write_ptr == fp->_IO_write_base
54 && fp->_IO_save_base == NULL)
55 #elif defined __sferror || defined __DragonFly__ || defined __ANDROID__
56 /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
57 # if defined __SL64 && defined __SCLE /* Cygwin */
58 if ((fp->_flags & __SL64) == 0)
59 {
60 /* Cygwin 1.5.0 through 1.5.24 failed to open stdin in 64-bit
61 mode; but has an fseeko that requires 64-bit mode. */
62 FILE *tmp = fopen ("/dev/null", "r");
63 if (!tmp)
64 return -1;
65 fp->_flags |= __SL64;
66 fp->_seek64 = tmp->_seek64;
67 fclose (tmp);
68 }
69 # endif
70 if (fp_->_p == fp_->_bf._base
71 && fp_->_r == 0
72 && fp_->_w == ((fp_->_flags & (__SLBF | __SNBF | __SRD)) == 0 /* fully buffered and not currently reading? */
73 ? fp_->_bf._size
74 : 0)
75 && fp_ub._base == NULL)
76 #elif defined __EMX__ /* emx+gcc */
77 if (fp->_ptr == fp->_buffer
78 && fp->_rcount == 0
79 && fp->_wcount == 0
80 && fp->_ungetc_count == 0)
81 #elif defined __minix /* Minix */
82 if (fp_->_ptr == fp_->_buf
83 && (fp_->_ptr == NULL || fp_->_count == 0))
84 #elif defined _IOERR /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, UnixWare, mingw, MSVC, NonStop Kernel, OpenVMS */
85 if (fp_->_ptr == fp_->_base
86 && (fp_->_ptr == NULL || fp_->_cnt == 0))
87 #elif defined __UCLIBC__ /* uClibc */
88 if (((fp->__modeflags & __FLAG_WRITING) == 0
89 || fp->__bufpos == fp->__bufstart)
90 && ((fp->__modeflags & (__FLAG_READONLY | __FLAG_READING)) == 0
91 || fp->__bufpos == fp->__bufread))
92 #elif defined __QNX__ /* QNX */
93 if ((fp->_Mode & 0x2000 /* _MWRITE */ ? fp->_Next == fp->_Buf : fp->_Next == fp->_Rend)
94 && fp->_Rback == fp->_Back + sizeof (fp->_Back)
95 && fp->_Rsave == NULL)
96 #elif defined __MINT__ /* Atari FreeMiNT */
97 if (fp->__bufp == fp->__buffer
98 && fp->__get_limit == fp->__bufp
99 && fp->__put_limit == fp->__bufp
100 && !fp->__pushed_back)
101 #elif defined EPLAN9 /* Plan9 */
102 if (fp->rp == fp->buf
103 && fp->wp == fp->buf)
104 #elif FUNC_FFLUSH_STDIN < 0 && 200809 <= _POSIX_VERSION
105 /* Cross-compiling to some other system advertising conformance to
106 POSIX.1-2008 or later. Assume fseeko and fflush work as advertised.
107 If this assumption is incorrect, please report the bug to
108 bug-gnulib. */
109 if (0)
110 #else
111 #error "Please port gnulib fseeko.c to your platform! Look at the code in fseeko.c, then report this to bug-gnulib."
112 #endif
113 {
114 /* We get here when an fflush() call immediately preceded this one (or
115 if ftell() has created buffers but no I/O has occurred on a
116 newly-opened stream). We know there are no buffers. */
117 off_t pos = lseek (fileno (fp), offset, whence);
118 if (pos == -1)
119 {
120 #if defined __sferror || defined __DragonFly__ || defined __ANDROID__
121 /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
122 fp_->_flags &= ~__SOFF;
123 #endif
124 return -1;
125 }
126
127 #if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
128 /* GNU libc, BeOS, Haiku, Linux libc5 */
129 fp->_flags &= ~_IO_EOF_SEEN;
130 fp->_offset = pos;
131 #elif defined __sferror || defined __DragonFly__ || defined __ANDROID__
132 /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
133 # if defined __CYGWIN__ || (defined __NetBSD__ && __NetBSD_Version__ >= 600000000) || defined __minix
134 /* fp_->_offset is typed as an integer. */
135 fp_->_offset = pos;
136 # else
137 /* fp_->_offset is an fpos_t. */
138 {
139 /* Use a union, since on NetBSD, the compilation flags
140 determine whether fpos_t is typedef'd to off_t or a struct
141 containing a single off_t member. */
142 union
143 {
144 fpos_t f;
145 off_t o;
146 } u;
147 u.o = pos;
148 fp_->_offset = u.f;
149 }
150 # endif
151 fp_->_flags |= __SOFF;
152 fp_->_flags &= ~__SEOF;
153 #elif defined __EMX__ /* emx+gcc */
154 fp->_flags &= ~_IOEOF;
155 #elif defined _IOERR /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, UnixWare, mingw, MSVC, NonStop Kernel, OpenVMS */
156 fp_->_flag &= ~_IOEOF;
157 #elif defined __MINT__ /* Atari FreeMiNT */
158 fp->__offset = pos;
159 fp->__eof = 0;
160 #endif
161 return 0;
162 }
163 return fseeko (fp, offset, whence);
164 }