1 /* Retrieve information about a FILE stream.
2 Copyright (C) 2007-2021 Free Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation; either version 3 of the License, or
7 (at your option) any later version.
9 This program 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 General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <https://www.gnu.org/licenses/>. */
20 #include "freadahead.h"
23 #include "stdio-impl.h"
25 #if defined __DragonFly__
26 /* Defined in libc, but not declared in <stdio.h>. */
27 extern size_t __sreadahead (FILE *);
30 /* This file is not used on systems that have the __freadahead function,
36 #if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
37 /* GNU libc, BeOS, Haiku, Linux libc5 */
38 if (fp->_IO_write_ptr > fp->_IO_write_base)
40 return (fp->_IO_read_end - fp->_IO_read_ptr)
41 + (fp->_flags & _IO_IN_BACKUP ? fp->_IO_save_end - fp->_IO_save_base :
43 #elif defined __sferror || defined __DragonFly__ || defined __ANDROID__
44 /* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
45 if ((fp_->_flags & __SWR) != 0 || fp_->_r < 0)
47 # if defined __DragonFly__
48 return __sreadahead (fp);
51 + (HASUB (fp) ? fp_->_ur : 0);
53 #elif defined __EMX__ /* emx+gcc */
54 if ((fp->_flags & _IOWRT) != 0)
56 /* Note: fp->_ungetc_count > 0 implies fp->_rcount <= 0,
57 fp->_ungetc_count = 0 implies fp->_rcount >= 0. */
59 (fp->_ungetc_count == 0 ? fp->_rcount : fp->_ungetc_count - fp->_rcount) */
60 return (fp->_rcount > 0 ? fp->_rcount : fp->_ungetc_count - fp->_rcount);
61 #elif defined __minix /* Minix */
62 if ((fp_->_flags & _IOWRITING) != 0)
65 #elif defined _IOERR /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, UnixWare, mingw, MSVC, NonStop Kernel, OpenVMS */
66 if ((fp_->_flag & _IOWRT) != 0)
69 #elif defined __UCLIBC__ /* uClibc */
70 # ifdef __STDIO_BUFFERS
71 if (fp->__modeflags & __FLAG_WRITING)
73 return (fp->__bufread - fp->__bufpos)
74 + (fp->__modeflags & __FLAG_UNGOT ? 1 : 0);
78 #elif defined __QNX__ /* QNX */
79 if ((fp->_Mode & 0x2000 /* _MWRITE */) != 0)
81 /* fp->_Buf <= fp->_Next <= fp->_Rend,
82 and fp->_Rend may be overridden by fp->_Rsave. */
83 return ((fp->_Rsave ? fp->_Rsave : fp->_Rend) - fp->_Next)
84 + (fp->_Mode & 0x4000 /* _MBYTE */
85 ? (fp->_Back + sizeof (fp->_Back)) - fp->_Rback
87 #elif defined __MINT__ /* Atari FreeMiNT */
88 if (!fp->__mode.__read)
90 return (fp->__pushed_back
91 ? fp->__get_limit - fp->__pushback_bufp + 1
92 : fp->__get_limit - fp->__bufp);
93 #elif defined EPLAN9 /* Plan9 */
94 if (fp->state == 4 /* WR */ || fp->rp >= fp->wp)
96 return fp->wp - fp->rp;
97 #elif defined SLOW_BUT_NO_HACKS /* users can define this */
101 #error "Please port gnulib freadahead.c to your platform! Look at the definition of fflush, fread, ungetc on your system, then report this to bug-gnulib."