1 | /* |
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2 | * Copyright (c) 1990 The Regents of the University of California. |
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3 | * All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms are permitted |
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6 | * provided that the above copyright notice and this paragraph are |
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7 | * duplicated in all such forms and that any documentation, |
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8 | * advertising materials, and other materials related to such |
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9 | * distribution and use acknowledge that the software was developed |
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10 | * by the University of California, Berkeley. The name of the |
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11 | * University may not be used to endorse or promote products derived |
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12 | * from this software without specific prior written permission. |
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13 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR |
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14 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED |
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15 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
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16 | */ |
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17 | |
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18 | /* |
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19 | FUNCTION |
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20 | <<fileno>>, <<fileno_unlocked>>---return file descriptor associated with stream |
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21 | |
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22 | INDEX |
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23 | fileno |
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24 | INDEX |
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25 | fileno_unlocked |
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26 | |
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27 | SYNOPSIS |
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28 | #include <stdio.h> |
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29 | int fileno(FILE *<[fp]>); |
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30 | |
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31 | #define _BSD_SOURCE |
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32 | #include <stdio.h> |
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33 | int fileno_unlocked(FILE *<[fp]>); |
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34 | |
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35 | DESCRIPTION |
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36 | You can use <<fileno>> to return the file descriptor identified by <[fp]>. |
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37 | |
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38 | <<fileno_unlocked>> is a non-thread-safe version of <<fileno>>. |
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39 | <<fileno_unlocked>> may only safely be used within a scope |
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40 | protected by flockfile() (or ftrylockfile()) and funlockfile(). This |
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41 | function may safely be used in a multi-threaded program if and only |
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42 | if they are called while the invoking thread owns the (FILE *) |
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43 | object, as is the case after a successful call to the flockfile() or |
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44 | ftrylockfile() functions. If threads are disabled, then |
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45 | <<fileno_unlocked>> is equivalent to <<fileno>>. |
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46 | |
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47 | RETURNS |
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48 | <<fileno>> returns a non-negative integer when successful. |
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49 | If <[fp]> is not an open stream, <<fileno>> returns -1. |
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50 | |
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51 | PORTABILITY |
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52 | <<fileno>> is not part of ANSI C. |
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53 | POSIX requires <<fileno>>. |
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54 | |
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55 | <<fileno_unlocked>> is a BSD extension also provided by GNU libc. |
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56 | |
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57 | Supporting OS subroutines required: none. |
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58 | */ |
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59 | |
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60 | #include <_ansi.h> |
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61 | #include <stdio.h> |
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62 | #include <errno.h> |
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63 | #include "local.h" |
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64 | |
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65 | int |
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66 | fileno (FILE * f) |
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67 | { |
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68 | int result; |
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69 | CHECK_INIT (_REENT, f); |
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70 | _newlib_flockfile_start (f); |
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71 | if (f->_flags) |
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72 | result = __sfileno (f); |
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73 | else |
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74 | { |
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75 | result = -1; |
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76 | _REENT->_errno = EBADF; |
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77 | } |
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78 | _newlib_flockfile_end (f); |
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79 | return result; |
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80 | } |
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