gnulib/import/m4/fcntl.m4

   1 # fcntl.m4 serial 9
   2 dnl Copyright (C) 2009-2016 Free Software Foundation, Inc.
   3 dnl This file is free software; the Free Software Foundation
   4 dnl gives unlimited permission to copy and/or distribute it,
   5 dnl with or without modifications, as long as this notice is preserved.
   6
   7 # For now, this module ensures that fcntl()
   8 # - supports F_DUPFD correctly
   9 # - supports or emulates F_DUPFD_CLOEXEC
  10 # - supports F_GETFD
  11 # Still to be ported to mingw:
  12 # - F_SETFD
  13 # - F_GETFL, F_SETFL
  14 # - F_GETOWN, F_SETOWN
  15 # - F_GETLK, F_SETLK, F_SETLKW
  16 AC_DEFUN([gl_FUNC_FCNTL],
  17 [
  18   dnl Persuade glibc to expose F_DUPFD_CLOEXEC.
  19   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
  20   AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
  21   AC_REQUIRE([AC_CANONICAL_HOST])
  22   AC_CHECK_FUNCS_ONCE([fcntl])
  23   if test $ac_cv_func_fcntl = no; then
  24     gl_REPLACE_FCNTL
  25   else
  26     dnl cygwin 1.5.x F_DUPFD has wrong errno, and allows negative target
  27     dnl haiku alpha 2 F_DUPFD has wrong errno
  28     AC_CACHE_CHECK([whether fcntl handles F_DUPFD correctly],
  29       [gl_cv_func_fcntl_f_dupfd_works],
  30       [AC_RUN_IFELSE(
  31          [AC_LANG_PROGRAM(
  32             [[#include <errno.h>
  33               #include <fcntl.h>
  34               #include <limits.h>
  35               #include <sys/resource.h>
  36               #include <unistd.h>
  37               #ifndef RLIM_SAVED_CUR
  38               # define RLIM_SAVED_CUR RLIM_INFINITY
  39               #endif
  40               #ifndef RLIM_SAVED_MAX
  41               # define RLIM_SAVED_MAX RLIM_INFINITY
  42               #endif
  43             ]],
  44             [[int result = 0;
  45               int bad_fd = INT_MAX;
  46               struct rlimit rlim;
  47               if (getrlimit (RLIMIT_NOFILE, &rlim) == 0
  48                   && 0 <= rlim.rlim_cur && rlim.rlim_cur <= INT_MAX
  49                   && rlim.rlim_cur != RLIM_INFINITY
  50                   && rlim.rlim_cur != RLIM_SAVED_MAX
  51                   && rlim.rlim_cur != RLIM_SAVED_CUR)
  52                 bad_fd = rlim.rlim_cur;
  53               if (fcntl (0, F_DUPFD, -1) != -1) result |= 1;
  54               if (errno != EINVAL) result |= 2;
  55               if (fcntl (0, F_DUPFD, bad_fd) != -1) result |= 4;
  56               if (errno != EINVAL) result |= 8;
  57               /* On OS/2 kLIBC, F_DUPFD does not work on a directory fd */
  58               {
  59                 int fd;
  60                 fd = open (".", O_RDONLY);
  61                 if (fd == -1)
  62                   result |= 16;
  63                 else if (fcntl (fd, F_DUPFD, STDERR_FILENO + 1) == -1)
  64                   result |= 32;
  65
  66                 close (fd);
  67               }
  68               return result;]])],
  69          [gl_cv_func_fcntl_f_dupfd_works=yes],
  70          [gl_cv_func_fcntl_f_dupfd_works=no],
  71          [case $host_os in
  72             aix* | cygwin* | haiku*)
  73                gl_cv_func_fcntl_f_dupfd_works="guessing no" ;;
  74             *) gl_cv_func_fcntl_f_dupfd_works="guessing yes" ;;
  75           esac])])
  76     case $gl_cv_func_fcntl_f_dupfd_works in
  77       *yes) ;;
  78       *) gl_REPLACE_FCNTL
  79         AC_DEFINE([FCNTL_DUPFD_BUGGY], [1], [Define this to 1 if F_DUPFD
  80           behavior does not match POSIX]) ;;
  81     esac
  82
  83     dnl Many systems lack F_DUPFD_CLOEXEC
  84     AC_CACHE_CHECK([whether fcntl understands F_DUPFD_CLOEXEC],
  85       [gl_cv_func_fcntl_f_dupfd_cloexec],
  86       [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
  87 #include <fcntl.h>
  88 #ifndef F_DUPFD_CLOEXEC
  89 choke me
  90 #endif
  91          ]])],
  92          [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
  93 #ifdef __linux__
  94 /* The Linux kernel only added F_DUPFD_CLOEXEC in 2.6.24, so we always replace
  95    it to support the semantics on older kernels that failed with EINVAL.  */
  96 choke me
  97 #endif
  98            ]])],
  99            [gl_cv_func_fcntl_f_dupfd_cloexec=yes],
 100            [gl_cv_func_fcntl_f_dupfd_cloexec="needs runtime check"])],
 101          [gl_cv_func_fcntl_f_dupfd_cloexec=no])])
 102     if test "$gl_cv_func_fcntl_f_dupfd_cloexec" != yes; then
 103       gl_REPLACE_FCNTL
 104       dnl No witness macro needed for this bug.
 105     fi
 106   fi
 107   dnl Replace fcntl() for supporting the gnulib-defined fchdir() function,
 108   dnl to keep fchdir's bookkeeping up-to-date.
 109   m4_ifdef([gl_FUNC_FCHDIR], [
 110     gl_TEST_FCHDIR
 111     if test $HAVE_FCHDIR = 0; then
 112       gl_REPLACE_FCNTL
 113     fi
 114   ])
 115 ])
 116
 117 AC_DEFUN([gl_REPLACE_FCNTL],
 118 [
 119   AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
 120   AC_CHECK_FUNCS_ONCE([fcntl])
 121   if test $ac_cv_func_fcntl = no; then
 122     HAVE_FCNTL=0
 123   else
 124     REPLACE_FCNTL=1
 125   fi
 126 ])