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/* Retrieve information about a FILE stream.
Copyright (C) 2007-2023 Free Software Foundation, Inc.
This file is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include "freadahead.h"
#include <stdlib.h>
#include "stdio-impl.h"
#if defined __DragonFly__
/* Defined in libc, but not declared in <stdio.h>. */
extern size_t __sreadahead (FILE *);
#endif
/* This file is not used on systems that have the __freadahead function,
namely musl libc. */
size_t
freadahead (FILE *fp)
{
#if defined _IO_EOF_SEEN || defined _IO_ftrylockfile || __GNU_LIBRARY__ == 1
/* GNU libc, BeOS, Haiku, Linux libc5 */
if (fp->_IO_write_ptr > fp->_IO_write_base)
return 0;
return (fp->_IO_read_end - fp->_IO_read_ptr)
+ (fp->_flags & _IO_IN_BACKUP ? fp->_IO_save_end - fp->_IO_save_base :
0);
#elif defined __sferror || defined __DragonFly__ || defined __ANDROID__
/* FreeBSD, NetBSD, OpenBSD, DragonFly, Mac OS X, Cygwin, Minix 3, Android */
if ((fp_->_flags & __SWR) != 0 || fp_->_r < 0)
return 0;
# if defined __DragonFly__
return __sreadahead (fp);
# else
return fp_->_r
+ (HASUB (fp) ? fp_->_ur : 0);
# endif
#elif defined __EMX__ /* emx+gcc */
if ((fp->_flags & _IOWRT) != 0)
return 0;
/* Note: fp->_ungetc_count > 0 implies fp->_rcount <= 0,
fp->_ungetc_count = 0 implies fp->_rcount >= 0. */
/* equivalent to
(fp->_ungetc_count == 0 ? fp->_rcount : fp->_ungetc_count - fp->_rcount) */
return (fp->_rcount > 0 ? fp->_rcount : fp->_ungetc_count - fp->_rcount);
#elif defined __minix /* Minix */
if ((fp_->_flags & _IOWRITING) != 0)
return 0;
return fp_->_count;
#elif defined _IOERR /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, UnixWare, mingw, MSVC, NonStop Kernel, OpenVMS */
if ((fp_->_flag & _IOWRT) != 0)
return 0;
return fp_->_cnt;
#elif defined __UCLIBC__ /* uClibc */
# ifdef __STDIO_BUFFERS
if (fp->__modeflags & __FLAG_WRITING)
return 0;
return (fp->__bufread - fp->__bufpos)
+ (fp->__modeflags & __FLAG_UNGOT ? 1 : 0);
# else
return 0;
# endif
#elif defined __QNX__ /* QNX */
if ((fp->_Mode & 0x2000 /* _MWRITE */) != 0)
return 0;
/* fp->_Buf <= fp->_Next <= fp->_Rend,
and fp->_Rend may be overridden by fp->_Rsave. */
return ((fp->_Rsave ? fp->_Rsave : fp->_Rend) - fp->_Next)
+ (fp->_Mode & 0x4000 /* _MBYTE */
? (fp->_Back + sizeof (fp->_Back)) - fp->_Rback
: 0);
#elif defined __MINT__ /* Atari FreeMiNT */
if (!fp->__mode.__read)
return 0;
return (fp->__pushed_back
? fp->__get_limit - fp->__pushback_bufp + 1
: fp->__get_limit - fp->__bufp);
#elif defined EPLAN9 /* Plan9 */
if (fp->state == 4 /* WR */ || fp->rp >= fp->wp)
return 0;
return fp->wp - fp->rp;
#elif defined SLOW_BUT_NO_HACKS /* users can define this */
abort ();
return 0;
#else
#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."
#endif
}
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