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., 51 Franklin Street - Fifth Floor,
  19 Boston, MA 02110-1301, 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 void unlock_std_streams (void)
  32
  33 If the OS supports it, ensure that the standard I/O streams,
  34 @code{stdin}, @code{stdout} and @code{stderr} are setup to avoid any
  35 multi-threaded locking.  Otherwise do nothing.
  36
  37 @end deftypefn
  38
  39 @deftypefn Extension {FILE *} fopen_unlocked (const char *@var{path}, const char * @var{mode})
  40
  41 Opens and returns a @code{FILE} pointer via @code{fopen}.  If the
  42 operating system supports it, ensure that the stream is setup to avoid
  43 any multi-threaded locking.  Otherwise return the @code{FILE} pointer
  44 unchanged.
  45
  46 @end deftypefn
  47
  48 @deftypefn Extension {FILE *} fdopen_unlocked (int @var{fildes}, const char * @var{mode})
  49
  50 Opens and returns a @code{FILE} pointer via @code{fdopen}.  If the
  51 operating system supports it, ensure that the stream is setup to avoid
  52 any multi-threaded locking.  Otherwise return the @code{FILE} pointer
  53 unchanged.
  54
  55 @end deftypefn
  56
  57 @deftypefn Extension {FILE *} freopen_unlocked (const char * @var{path}, const char * @var{mode}, FILE * @var{stream})
  58
  59 Opens and returns a @code{FILE} pointer via @code{freopen}.  If the
  60 operating system supports it, ensure that the stream is setup to avoid
  61 any multi-threaded locking.  Otherwise return the @code{FILE} pointer
  62 unchanged.
  63
  64 @end deftypefn
  65
  66 */
  67
  68 #ifdef HAVE_CONFIG_H
  69 #include "config.h"
  70 #endif
  71 #include <stdio.h>
  72 #ifdef HAVE_STDIO_EXT_H
  73 #include <stdio_ext.h>
  74 #endif
  75
  76 #include "libiberty.h"
  77
  78 /* This is an inline helper function to consolidate attempts to unlock
  79    a stream.  */
  80
  81 static inline void
  82 unlock_1 (FILE *const fp ATTRIBUTE_UNUSED)
  83 {
  84 #if defined(HAVE___FSETLOCKING) && defined(FSETLOCKING_BYCALLER)
  85   if (fp)
  86     __fsetlocking (fp, FSETLOCKING_BYCALLER);
  87 #endif
  88 }
  89
  90 void
  91 unlock_stream (FILE *fp)
  92 {
  93   unlock_1 (fp);
  94 }
  95
  96 void
  97 unlock_std_streams (void)
  98 {
  99   unlock_1 (stdin);
 100   unlock_1 (stdout);
 101   unlock_1 (stderr);
 102 }
 103
 104 FILE *
 105 fopen_unlocked (const char *path, const char *mode)
 106 {
 107   FILE *const fp = fopen (path, mode);
 108   unlock_1 (fp);
 109   return fp;
 110 }
 111
 112 FILE *
 113 fdopen_unlocked (int fildes, const char *mode)
 114 {
 115   FILE *const fp = fdopen (fildes, mode);
 116   unlock_1 (fp);
 117   return fp;
 118 }
 119
 120 FILE *
 121 freopen_unlocked (const char *path, const char *mode, FILE *stream)
 122 {
 123   FILE *const fp = freopen (path, mode, stream);
 124   unlock_1 (fp);
 125   return fp;
 126 }