toolchain/gcc/newlib/libc/stdio/fflush.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  * advertising materials, and 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 <<fflush>>---flush buffered file output
  21
  22 INDEX
  23         fflush
  24
  25 ANSI_SYNOPSIS
  26         #include <stdio.h>
  27         int fflush(FILE *<[fp]>);
  28
  29 TRAD_SYNOPSIS
  30         #include <stdio.h>
  31         int fflush(<[fp]>)
  32         FILE *<[fp]>;
  33
  34 DESCRIPTION
  35 The <<stdio>> output functions can buffer output before delivering it
  36 to the host system, in order to minimize the overhead of system calls.
  37
  38 Use <<fflush>> to deliver any such pending output (for the file
  39 or stream identified by <[fp]>) to the host system.
  40
  41 If <[fp]> is <<NULL>>, <<fflush>> delivers pending output from all
  42 open files.
  43
  44 RETURNS
  45 <<fflush>> returns <<0>> unless it encounters a write error; in that
  46 situation, it returns <<EOF>>.
  47
  48 PORTABILITY
  49 ANSI C requires <<fflush>>.
  50
  51 No supporting OS subroutines are required.
  52 */
  53
  54 #include <stdio.h>
  55 #include "local.h"
  56
  57 /* Flush a single file, or (if fp is NULL) all files.  */
  58
  59 int
  60 _DEFUN (fflush, (fp),
  61         register FILE * fp)
  62 {
  63   register unsigned char *p;
  64   register int n, t;
  65
  66   if (fp == NULL)
  67     return _fwalk (_GLOBAL_REENT, fflush);
  68
  69   _flockfile(fp);
  70
  71   CHECK_INIT (fp);
  72
  73   t = fp->_flags;
  74   if ((t & __SWR) == 0 || (p = fp->_bf._base) == NULL)
  75     {
  76       _funlockfile(fp);
  77       return 0;
  78     }
  79   n = fp->_p - p;               /* write this much */
  80
  81   /*
  82    * Set these immediately to avoid problems with longjmp
  83    * and to allow exchange buffering (via setvbuf) in user
  84    * write function.
  85    */
  86   fp->_p = p;
  87   fp->_w = t & (__SLBF | __SNBF) ? 0 : fp->_bf._size;
  88
  89   while (n > 0)
  90     {
  91       t = (*fp->_write) (fp->_cookie, (char *) p, n);
  92       if (t <= 0)
  93         {
  94           fp->_flags |= __SERR;
  95           _funlockfile(fp);
  96           return EOF;
  97         }
  98       p += t;
  99       n -= t;
 100     }
 101   _funlockfile(fp);
 102   return 0;
 103 }