newlib/libc/stdio/getc_u.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 <<getc_unlocked>>---non-thread-safe version of getc (macro)
  21
  22 INDEX
  23         getc_unlocked
  24 INDEX
  25         _getc_unlocked_r
  26
  27 SYNOPSIS
  28         #include <stdio.h>
  29         int getc_unlocked(FILE *<[fp]>);
  30
  31         #include <stdio.h>
  32         int _getc_unlocked_r(FILE *<[fp]>);
  33
  34 DESCRIPTION
  35 <<getc_unlocked>> is a non-thread-safe version of <<getc>> declared in
  36 <<stdio.h>>.  <<getc_unlocked>> may only safely be used within a scope
  37 protected by flockfile() (or ftrylockfile()) and funlockfile().  These
  38 functions may safely be used in a multi-threaded program if and only
  39 if they are called while the invoking thread owns the ( FILE *)
  40 object, as is the case after a successful call to the flockfile() or
  41 ftrylockfile() functions.  If threads are disabled, then
  42 <<getc_unlocked>> is equivalent to <<getc>>.
  43
  44 The <<_getc_unlocked_r>> function is simply the reentrant version of
  45 <<get_unlocked>> which passes an additional reentrancy structure pointer
  46 argument: <[ptr]>.
  47
  48 RETURNS
  49 See <<getc>>.
  50
  51 PORTABILITY
  52 POSIX 1003.1 requires <<getc_unlocked>>.  <<getc_unlocked>> may be
  53 implemented as a macro, so arguments should not have side-effects.
  54
  55 Supporting OS subroutines required: <<close>>, <<fstat>>, <<isatty>>,
  56 <<lseek>>, <<read>>, <<sbrk>>, <<write>>.  */
  57
  58 #if defined(LIBC_SCCS) && !defined(lint)
  59 static char sccsid[] = "%W% (Berkeley) %G%";
  60 #endif /* LIBC_SCCS and not lint */
  61
  62 #include <_ansi.h>
  63 #include <stdio.h>
  64
  65 /*
  66  * A subroutine version of the macro getc_unlocked.
  67  */
  68
  69 #undef getc_unlocked
  70
  71 int
  72 _getc_unlocked_r (struct _reent *ptr,
  73        register FILE *fp)
  74 {
  75   /* CHECK_INIT is called (eventually) by __srefill_r.  */
  76
  77   return __sgetc_r (ptr, fp);
  78 }
  79
  80 #ifndef _REENT_ONLY
  81
  82 int
  83 getc_unlocked (register FILE *fp)
  84 {
  85   return __sgetc_r (_REENT, fp);
  86 }
  87
  88 #endif /* !_REENT_ONLY */