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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