| /* Retrieve information about a FILE stream. |
| Copyright (C) 2007-2020 Free Software Foundation, Inc. |
| |
| This program is free software: you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 3 of the License, or |
| (at your option) any later version. |
| |
| This program 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 General Public License for more details. |
| |
| You should have received a copy of the GNU 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, 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 |
| } |