m4/fcntl_h.m4

   1 # serial 6
   2 # Configure fcntl.h.
   3 dnl Copyright (C) 2006, 2007, 2009 Free Software Foundation, Inc.
   4 dnl This file is free software; the Free Software Foundation
   5 dnl gives unlimited permission to copy and/or distribute it,
   6 dnl with or without modifications, as long as this notice is preserved.
   7
   8 dnl Written by Paul Eggert.
   9
  10 AC_DEFUN([gl_FCNTL_H],
  11 [
  12   AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
  13   AC_REQUIRE([gl_FCNTL_O_FLAGS])
  14   gl_CHECK_NEXT_HEADERS([fcntl.h])
  15   FCNTL_H='fcntl.h'
  16   AC_SUBST([FCNTL_H])
  17 ])
  18
  19 # Test whether the flags O_NOATIME and O_NOFOLLOW actually work.
  20 # Define HAVE_WORKING_O_NOATIME to 1 if O_NOATIME works, or to 0 otherwise.
  21 # Define HAVE_WORKING_O_NOFOLLOW to 1 if O_NOFOLLOW works, or to 0 otherwise.
  22 AC_DEFUN([gl_FCNTL_O_FLAGS],
  23 [
  24   dnl Persuade glibc <fcntl.h> to define O_NOATIME and O_NOFOLLOW.
  25   AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
  26   AC_CACHE_CHECK([for working fcntl.h], [gl_cv_header_working_fcntl_h],
  27     [AC_RUN_IFELSE(
  28        [AC_LANG_PROGRAM(
  29           [[#include <sys/types.h>
  30            #include <sys/stat.h>
  31            #include <unistd.h>
  32            #include <fcntl.h>
  33            #ifndef O_NOATIME
  34             #define O_NOATIME 0
  35            #endif
  36            #ifndef O_NOFOLLOW
  37             #define O_NOFOLLOW 0
  38            #endif
  39            static int const constants[] =
  40             {
  41               O_CREAT, O_EXCL, O_NOCTTY, O_TRUNC, O_APPEND,
  42               O_NONBLOCK, O_SYNC, O_ACCMODE, O_RDONLY, O_RDWR, O_WRONLY
  43             };
  44           ]],
  45           [[
  46             int status = !constants;
  47             {
  48               static char const sym[] = "conftest.sym";
  49               if (symlink (".", sym) != 0
  50                   || close (open (sym, O_RDONLY | O_NOFOLLOW)) == 0)
  51                 status |= 32;
  52               unlink (sym);
  53             }
  54             {
  55               static char const file[] = "confdefs.h";
  56               int fd = open (file, O_RDONLY | O_NOATIME);
  57               char c;
  58               struct stat st0, st1;
  59               if (fd < 0
  60                   || fstat (fd, &st0) != 0
  61                   || sleep (1) != 0
  62                   || read (fd, &c, 1) != 1
  63                   || close (fd) != 0
  64                   || stat (file, &st1) != 0
  65                   || st0.st_atime != st1.st_atime)
  66                 status |= 64;
  67             }
  68             return status;]])],
  69        [gl_cv_header_working_fcntl_h=yes],
  70        [case $? in #(
  71         32) gl_cv_header_working_fcntl_h='no (bad O_NOFOLLOW)';; #(
  72         64) gl_cv_header_working_fcntl_h='no (bad O_NOATIME)';; #(
  73         96) gl_cv_header_working_fcntl_h='no (bad O_NOATIME, O_NOFOLLOW)';; #(
  74          *) gl_cv_header_working_fcntl_h='no';;
  75         esac],
  76        [gl_cv_header_working_fcntl_h=cross-compiling])])
  77
  78   case $gl_cv_header_working_fcntl_h in #(
  79   *O_NOATIME* | no | cross-compiling) ac_val=0;; #(
  80   *) ac_val=1;;
  81   esac
  82   AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOATIME], [$ac_val],
  83     [Define to 1 if O_NOATIME works.])
  84
  85   case $gl_cv_header_working_fcntl_h in #(
  86   *O_NOFOLLOW* | no | cross-compiling) ac_val=0;; #(
  87   *) ac_val=1;;
  88   esac
  89   AC_DEFINE_UNQUOTED([HAVE_WORKING_O_NOFOLLOW], [$ac_val],
  90     [Define to 1 if O_NOFOLLOW works.])
  91 ])
  92
  93 AC_DEFUN([gl_FCNTL_MODULE_INDICATOR],
  94 [
  95   dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
  96   AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
  97   GNULIB_[]m4_translit([$1],[abcdefghijklmnopqrstuvwxyz./-],[ABCDEFGHIJKLMNOPQRSTUVWXYZ___])=1
  98 ])
  99
 100 AC_DEFUN([gl_FCNTL_H_DEFAULTS],
 101 [
 102   GNULIB_OPEN=0;    AC_SUBST([GNULIB_OPEN])
 103   GNULIB_OPENAT=0;  AC_SUBST([GNULIB_OPENAT])
 104   dnl Assume proper GNU behavior unless another module says otherwise.
 105   HAVE_OPENAT=1;    AC_SUBST([HAVE_OPENAT])
 106   REPLACE_OPEN=0;   AC_SUBST([REPLACE_OPEN])
 107   REPLACE_OPENAT=0; AC_SUBST([REPLACE_OPENAT])
 108 ])