| 1 | /* Retrieve information about a FILE stream.
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| 2 | Copyright (C) 2007-2008 Free Software Foundation, Inc.
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| 3 |
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| 4 | This program is free software: you can redistribute it and/or modify
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| 5 | it under the terms of the GNU General Public License as published by
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| 6 | the Free Software Foundation; either version 3 of the License, or
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| 7 | (at your option) any later version.
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| 8 |
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| 9 | This program is distributed in the hope that it will be useful,
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| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 12 | GNU General Public License for more details.
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| 13 |
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| 14 | You should have received a copy of the GNU General Public License
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| 15 | along with this program. If not, see <http://www.gnu.org/licenses/>. */
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| 16 |
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| 17 | #include <config.h>
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| 18 |
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| 19 | /* Specification. */
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| 20 | #include "freadahead.h"
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| 21 |
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| 22 | #include <stdlib.h>
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| 23 | #include "stdio-impl.h"
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| 24 |
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| 25 | size_t
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| 26 | freadahead (FILE *fp)
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| 27 | {
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| 28 | #if defined _IO_ferror_unlocked || __GNU_LIBRARY__ == 1 /* GNU libc, BeOS, Linux libc5 */
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| 29 | if (fp->_IO_write_ptr > fp->_IO_write_base)
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| 30 | return 0;
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| 31 | return (fp->_IO_read_end - fp->_IO_read_ptr)
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| 32 | + (fp->_flags & _IO_IN_BACKUP ? fp->_IO_save_end - fp->_IO_save_base :
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| 33 | 0);
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| 34 | #elif defined __sferror || defined __DragonFly__ /* FreeBSD, NetBSD, OpenBSD, DragonFly, MacOS X, Cygwin */
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| 35 | if ((fp_->_flags & __SWR) != 0 || fp_->_r < 0)
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| 36 | return 0;
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| 37 | # if defined __DragonFly__
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| 38 | return __sreadahead (fp);
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| 39 | # else
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| 40 | return fp_->_r
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| 41 | + (HASUB (fp) ? fp_->_ur : 0);
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| 42 | # endif
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| 43 | #elif defined __EMX__ /* emx+gcc */
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| 44 | if ((fp->_flags & _IOWRT) != 0)
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| 45 | return 0;
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| 46 | /* Note: fp->_ungetc_count > 0 implies fp->_rcount <= 0,
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| 47 | fp->_ungetc_count = 0 implies fp->_rcount >= 0. */
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| 48 | /* equivalent to
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| 49 | (fp->_ungetc_count == 0 ? fp->_rcount : fp->_ungetc_count - fp->_rcount) */
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| 50 | return (fp->_rcount > 0 ? fp->_rcount : fp->_ungetc_count - fp->_rcount);
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| 51 | #elif defined _IOERR /* AIX, HP-UX, IRIX, OSF/1, Solaris, OpenServer, mingw */
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| 52 | if ((fp_->_flag & _IOWRT) != 0)
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| 53 | return 0;
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| 54 | return fp_->_cnt;
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| 55 | #elif defined __UCLIBC__ /* uClibc */
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| 56 | # ifdef __STDIO_BUFFERS
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| 57 | if (fp->__modeflags & __FLAG_WRITING)
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| 58 | return 0;
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| 59 | return (fp->__bufread - fp->__bufpos)
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| 60 | + (fp->__modeflags & __FLAG_UNGOT ? 1 : 0);
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| 61 | # else
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| 62 | return 0;
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| 63 | # endif
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| 64 | #elif defined __QNX__ /* QNX */
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| 65 | if ((fp->_Mode & 0x2000 /* _MWRITE */) != 0)
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| 66 | return 0;
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| 67 | /* fp->_Buf <= fp->_Next <= fp->_Rend,
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| 68 | and fp->_Rend may be overridden by fp->_Rsave. */
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| 69 | return ((fp->_Rsave ? fp->_Rsave : fp->_Rend) - fp->_Next)
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| 70 | + (fp->_Mode & 0x4000 /* _MBYTE */
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| 71 | ? (fp->_Back + sizeof (fp->_Back)) - fp->_Rback
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| 72 | : 0);
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| 73 | #elif defined SLOW_BUT_NO_HACKS /* users can define this */
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| 74 | abort ();
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| 75 | return 0;
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| 76 | #else
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| 77 | #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."
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| 78 | #endif
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| 79 | }
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