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  • Committer: Brian Thomason
  • Date: 2012-03-06 19:40:19 UTC
  • Revision ID: brian.thomason@canonical.com-20120306194019-f1lgtgb3r7sg21ee
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gnulib/m4/fcntl-o.m4
 
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# fcntl-o.m4 serial 3
 
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dnl Copyright (C) 2006, 2009-2011 Free Software Foundation, Inc.
 
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dnl This file is free software; the Free Software Foundation
 
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dnl gives unlimited permission to copy and/or distribute it,
 
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dnl with or without modifications, as long as this notice is preserved.
 
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dnl Written by Paul Eggert.
 
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# Test whether the flags O_NOATIME and O_NOFOLLOW actually work.
 
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# Define HAVE_WORKING_O_NOATIME to 1 if O_NOATIME works, or to 0 otherwise.
 
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# Define HAVE_WORKING_O_NOFOLLOW to 1 if O_NOFOLLOW works, or to 0 otherwise.
 
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AC_DEFUN([gl_FCNTL_O_FLAGS],
 
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[
 
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  dnl Persuade glibc <fcntl.h> to define O_NOATIME and O_NOFOLLOW.
 
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  dnl AC_USE_SYSTEM_EXTENSIONS was introduced in autoconf 2.60 and obsoletes
 
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  dnl AC_GNU_SOURCE.
 
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  m4_ifdef([AC_USE_SYSTEM_EXTENSIONS],
 
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    [AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])],
 
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    [AC_REQUIRE([AC_GNU_SOURCE])])
 
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  AC_CACHE_CHECK([for working fcntl.h], [gl_cv_header_working_fcntl_h],
 
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    [AC_RUN_IFELSE(
 
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       [AC_LANG_PROGRAM(
 
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          [[#include <sys/types.h>
 
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           #include <sys/stat.h>
 
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           #include <unistd.h>
 
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           #include <fcntl.h>
 
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           #ifndef O_NOATIME
 
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            #define O_NOATIME 0
 
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           #endif
 
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           #ifndef O_NOFOLLOW
 
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            #define O_NOFOLLOW 0
 
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           #endif
 
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           static int const constants[] =
 
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            {
 
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              O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND,
 
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              O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY
 
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            };
 
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          ]],
 
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          [[
 
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            int result = !constants;
 
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            {
 
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              static char const sym[] = "conftest.sym";
 
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              if (symlink (".", sym) != 0)
 
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                result |= 2;
 
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              else
 
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                {
 
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                  int fd = open (sym, O_RDONLY | O_NOFOLLOW);
 
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                  if (fd >= 0)
 
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                    {
 
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                      close (fd);
 
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                      result |= 4;
 
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                    }
 
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                }
 
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              unlink (sym);
 
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            }
 
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            {
 
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              static char const file[] = "confdefs.h";
 
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              int fd = open (file, O_RDONLY | O_NOATIME);
 
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              if (fd < 0)
 
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                result |= 8;
 
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              else
 
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                {
 
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                  struct stat st0;
 
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                  if (fstat (fd, &st0) != 0)
 
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                    result |= 16;
 
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                  else
 
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                    {
 
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                      char c;
 
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                      sleep (1);
 
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                      if (read (fd, &c, 1) != 1)
 
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                        result |= 24;
 
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                      else
 
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                        {
 
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                          if (close (fd) != 0)
 
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                            result |= 32;
 
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                          else
 
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                            {
 
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                              struct stat st1;
 
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                              if (stat (file, &st1) != 0)
 
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                                result |= 40;
 
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                              else
 
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                                if (st0.st_atime != st1.st_atime)
 
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                                  result |= 64;
 
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                            }
 
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                        }
 
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                    }
 
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                }
 
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            }
 
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            return result;]])],
 
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       [gl_cv_header_working_fcntl_h=yes],
 
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       [case $? in #(
 
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        4) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #(
 
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        64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #(
 
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        68) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #(
 
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         *) gl_cv_header_working_fcntl_h='no';;
 
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        esac],
 
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       [gl_cv_header_working_fcntl_h=cross-compiling])])
 
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  case $gl_cv_header_working_fcntl_h in #(
 
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  *O_NOATIME* | no | cross-compiling) ac_val=0;; #(
 
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  *) ac_val=1;;
 
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  esac
 
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  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val],
 
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    [Define to 1 if O_NOATIME works.])
 
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  case $gl_cv_header_working_fcntl_h in #(
 
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  *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #(
 
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  *) ac_val=1;;
 
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  esac
 
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  AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val],
 
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    [Define to 1 if O_NOFOLLOW works.])
 
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])