libiberty/fopen_unlocked.c

   1 /* Implement fopen_unlocked and related functions.
   2    Copyright (C) 2005 Free Software Foundation, Inc.
   3    Written by Kaveh R. Ghazi <ghazi@caip.rutgers.edu>.
   4
   5 This file is part of the libiberty library.
   6 Libiberty is free software; you can redistribute it and/or
   7 modify it under the terms of the GNU Library General Public
   8 License as published by the Free Software Foundation; either
   9 version 2 of the License, or (at your option) any later version.
  10
  11 Libiberty is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 Library General Public License for more details.
  15
  16 You should have received a copy of the GNU Library General Public
  17 License along with libiberty; see the file COPYING.LIB.  If
  18 not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21 /*
  22
  23 @deftypefn Extension void unlock_stream (FILE * @var{stream})
  24
  25 If the OS supports it, ensure that the supplied stream is setup to
  26 avoid any multi-threaded locking.  Otherwise leave the @code{FILE}
  27 pointer unchanged.  If the @var{stream} is @code{NULL} do nothing.
  28
  29 @end deftypefn
  30
  31 @deftypefn Extension FILE * fopen_unlocked (const char *@var{path}, const char * @var{mode})
  32
  33 Opens and returns a @code{FILE} pointer via @code{fopen}.  If the
  34 operating system supports it, ensure that the stream is setup to avoid
  35 any multi-threaded locking.  Otherwise return the @code{FILE} pointer
  36 unchanged.
  37
  38 @end deftypefn
  39
  40 @deftypefn Extension FILE * fdopen_unlocked (int @var{fildes}, const char * @var{mode})
  41
  42 Opens and returns a @code{FILE} pointer via @code{fdopen}.  If the
  43 operating system supports it, ensure that the stream is setup to avoid
  44 any multi-threaded locking.  Otherwise return the @code{FILE} pointer
  45 unchanged.
  46
  47 @end deftypefn
  48
  49 @deftypefn Extension FILE * freopen_unlocked (const char * @var{path}, const char * @var{mode}, FILE * @var{stream})
  50
  51 Opens and returns a @code{FILE} pointer via @code{freopen}.  If the
  52 operating system supports it, ensure that the stream is setup to avoid
  53 any multi-threaded locking.  Otherwise return the @code{FILE} pointer
  54 unchanged.
  55
  56 @end deftypefn
  57
  58 */
  59
  60 #ifdef HAVE_CONFIG_H
  61 #include "config.h"
  62 #endif
  63 #include <stdio.h>
  64 #ifdef HAVE_STDIO_EXT_H
  65 #include <stdio_ext.h>
  66 #endif
  67
  68 #include "libiberty.h"
  69
  70 /* This is an inline helper function to consolidate attempts to unlock
  71    a stream.  */
  72
  73 static inline void
  74 unlock_1 (FILE *const fp ATTRIBUTE_UNUSED)
  75 {
  76 #if defined(HAVE___FSETLOCKING) && defined(FSETLOCKING_BYCALLER)
  77   if (fp)
  78     __fsetlocking (fp, FSETLOCKING_BYCALLER);
  79 #endif
  80 }
  81
  82 void
  83 unlock_stream(FILE *fp)
  84 {
  85   unlock_1 (fp);
  86 }
  87
  88 FILE *
  89 fopen_unlocked (const char *path, const char *mode)
  90 {
  91   FILE *const fp = fopen (path, mode);
  92   unlock_1 (fp);
  93   return fp;
  94 }
  95
  96 FILE *
  97 fdopen_unlocked (int fildes, const char *mode)
  98 {
  99   FILE *const fp = fdopen (fildes, mode);
 100   unlock_1 (fp);
 101   return fp;
 102 }
 103
 104 FILE *
 105 freopen_unlocked (const char *path, const char *mode, FILE *stream)
 106 {
 107   FILE *const fp = freopen (path, mode, stream);
 108   unlock_1 (fp);
 109   return fp;
 110 }