newlib/libc/stdio/clearerr.c

   1 /*
   2  * Copyright (c) 1990 The Regents of the University of California.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms are permitted
   6  * provided that the above copyright notice and this paragraph are
   7  * duplicated in all such forms and that any documentation,
   8  * and/or other materials related to such
   9  * distribution and use acknowledge that the software was developed
  10  * by the University of California, Berkeley.  The name of the
  11  * University may not be used to endorse or promote products derived
  12  * from this software without specific prior written permission.
  13  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
  14  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
  15  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  16  */
  17
  18 /*
  19 FUNCTION
  20 <<clearerr>>, <<clearerr_unlocked>>---clear file or stream error indicator
  21
  22 INDEX
  23         clearerr
  24 INDEX
  25         clearerr_unlocked
  26
  27 SYNOPSIS
  28         #include <stdio.h>
  29         void clearerr(FILE *<[fp]>);
  30
  31         #define _BSD_SOURCE
  32         #include <stdio.h>
  33         void clearerr_unlocked(FILE *<[fp]>);
  34
  35 DESCRIPTION
  36 The <<stdio>> functions maintain an error indicator with each file
  37 pointer <[fp]>, to record whether any read or write errors have
  38 occurred on the associated file or stream.  Similarly, it maintains an
  39 end-of-file indicator to record whether there is no more data in the
  40 file.
  41
  42 Use <<clearerr>> to reset both of these indicators.
  43
  44 See <<ferror>> and <<feof>> to query the two indicators.
  45
  46 <<clearerr_unlocked>> is a non-thread-safe version of <<clearerr>>.
  47 <<clearerr_unlocked>> may only safely be used within a scope
  48 protected by flockfile() (or ftrylockfile()) and funlockfile().  This
  49 function may safely be used in a multi-threaded program if and only
  50 if they are called while the invoking thread owns the (FILE *)
  51 object, as is the case after a successful call to the flockfile() or
  52 ftrylockfile() functions.  If threads are disabled, then
  53 <<clearerr_unlocked>> is equivalent to <<clearerr>>.
  54
  55 RETURNS
  56 <<clearerr>> does not return a result.
  57
  58 PORTABILITY
  59 ANSI C requires <<clearerr>>.
  60
  61 <<clearerr_unlocked>> is a BSD extension also provided by GNU libc.
  62
  63 No supporting OS subroutines are required.
  64 */
  65
  66 #include <_ansi.h>
  67 #include <stdio.h>
  68 #include "local.h"
  69
  70 /* A subroutine version of the macro clearerr.  */
  71
  72 #undef  clearerr
  73
  74 void
  75 clearerr (FILE * fp)
  76 {
  77   CHECK_INIT(_REENT, fp);
  78   _newlib_flockfile_start (fp);
  79   __sclearerr (fp);
  80   _newlib_flockfile_end (fp);
  81 }