view m4/wctype_h.m4 @ 16869:38e6d30d7e4d

poll/select: prevent busy-waiting 2012-05-21 Paolo Bonzini <bonzini@gnu.org> poll/select: prevent busy-waiting. SwitchToThread() only gives away the rest of the current time slice to another thread in the current process. So if the thread that feeds the file decscriptor we're polling is not in the current process, we get busy-waiting. * lib/poll.c: Use SleepEx(1, TRUE) instead of SwitchToThread(). Patch from Theodore Leblond. * lib/select.c: Split polling out of the loop that sets the output fd_sets. Check for zero result and loop if the wait timeout is infinite.
author Paolo Bonzini <bonzini@gnu.org>
date Mon, 21 May 2012 09:52:42 +0200
parents ca49e9a6643d
children 3aff72f6c8ba
line wrap: on
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# wctype_h.m4 serial 17

dnl A placeholder for ISO C99 <wctype.h>, for platforms that lack it.

dnl Copyright (C) 2006-2012 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

dnl Written by Paul Eggert.

AC_DEFUN([gl_WCTYPE_H],
[
  AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
  AC_REQUIRE([AC_PROG_CC])
  AC_REQUIRE([AC_CANONICAL_HOST])
  AC_CHECK_FUNCS_ONCE([iswcntrl])
  if test $ac_cv_func_iswcntrl = yes; then
    HAVE_ISWCNTRL=1
  else
    HAVE_ISWCNTRL=0
  fi
  AC_SUBST([HAVE_ISWCNTRL])

  AC_REQUIRE([AC_C_INLINE])

  AC_REQUIRE([gt_TYPE_WINT_T])
  if test $gt_cv_c_wint_t = yes; then
    HAVE_WINT_T=1
  else
    HAVE_WINT_T=0
  fi
  AC_SUBST([HAVE_WINT_T])

  gl_CHECK_NEXT_HEADERS([wctype.h])
  if test $ac_cv_header_wctype_h = yes; then
    if test $ac_cv_func_iswcntrl = yes; then
      dnl Linux libc5 has an iswprint function that returns 0 for all arguments.
      dnl The other functions are likely broken in the same way.
      AC_CACHE_CHECK([whether iswcntrl works], [gl_cv_func_iswcntrl_works],
        [
          AC_RUN_IFELSE(
            [AC_LANG_SOURCE([[
               /* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be
                  included before <wchar.h>.
                  BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h>
                  must be included before <wchar.h>.  */
               #include <stddef.h>
               #include <stdio.h>
               #include <time.h>
               #include <wchar.h>
               #include <wctype.h>
               int main () { return iswprint ('x') == 0; }
            ]])],
            [gl_cv_func_iswcntrl_works=yes], [gl_cv_func_iswcntrl_works=no],
            [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <stdlib.h>
                          #if __GNU_LIBRARY__ == 1
                          Linux libc5 i18n is broken.
                          #endif]], [])],
              [gl_cv_func_iswcntrl_works="guessing yes"],
              [gl_cv_func_iswcntrl_works="guessing no"])
            ])
        ])
    fi
    HAVE_WCTYPE_H=1
  else
    HAVE_WCTYPE_H=0
  fi
  AC_SUBST([HAVE_WCTYPE_H])

  case "$gl_cv_func_iswcntrl_works" in
    *yes) REPLACE_ISWCNTRL=0 ;;
    *)    REPLACE_ISWCNTRL=1 ;;
  esac
  AC_SUBST([REPLACE_ISWCNTRL])

  if test $HAVE_ISWCNTRL = 0 || test $REPLACE_ISWCNTRL = 1; then
    dnl Redefine all of iswcntrl, ..., iswxdigit in <wctype.h>.
    :
  fi

  if test $REPLACE_ISWCNTRL = 1; then
    REPLACE_TOWLOWER=1
  else
    AC_CHECK_FUNCS([towlower])
    if test $ac_cv_func_towlower = yes; then
      REPLACE_TOWLOWER=0
    else
      AC_CHECK_DECLS([towlower],,,
        [[/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be
             included before <wchar.h>.
             BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h>
             must be included before <wchar.h>.  */
          #include <stddef.h>
          #include <stdio.h>
          #include <time.h>
          #include <wchar.h>
          #if HAVE_WCTYPE_H
          # include <wctype.h>
          #endif
        ]])
      if test $ac_cv_have_decl_towlower = yes; then
        dnl On Minix 3.1.8, the system's <wctype.h> declares towlower() and
        dnl towupper() although it does not have the functions. Avoid a
        dnl collision with gnulib's replacement.
        REPLACE_TOWLOWER=1
      else
        REPLACE_TOWLOWER=0
      fi
    fi
  fi
  AC_SUBST([REPLACE_TOWLOWER])

  if test $HAVE_ISWCNTRL = 0 || test $REPLACE_TOWLOWER = 1; then
    dnl Redefine towlower, towupper in <wctype.h>.
    :
  fi

  dnl We assume that the wctype() and iswctype() functions exist if and only
  dnl if the type wctype_t is defined in <wchar.h> or in <wctype.h> if that
  dnl exists.
  dnl HP-UX 11.00 declares all these in <wchar.h> and lacks <wctype.h>.
  AC_CACHE_CHECK([for wctype_t], [gl_cv_type_wctype_t],
    [AC_COMPILE_IFELSE(
       [AC_LANG_PROGRAM(
          [[/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be
               included before <wchar.h>.
               BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h>
               must be included before <wchar.h>.  */
            #include <stddef.h>
            #include <stdio.h>
            #include <time.h>
            #include <wchar.h>
            #if HAVE_WCTYPE_H
            # include <wctype.h>
            #endif
            wctype_t a;
          ]],
          [[]])],
       [gl_cv_type_wctype_t=yes],
       [gl_cv_type_wctype_t=no])
    ])
  if test $gl_cv_type_wctype_t = no; then
    HAVE_WCTYPE_T=0
  fi

  dnl We assume that the wctrans() and towctrans() functions exist if and only
  dnl if the type wctrans_t is defined in <wctype.h>.
  AC_CACHE_CHECK([for wctrans_t], [gl_cv_type_wctrans_t],
    [AC_COMPILE_IFELSE(
       [AC_LANG_PROGRAM(
          [[/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be
               included before <wchar.h>.
               BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h>
               must be included before <wchar.h>.  */
            #include <stddef.h>
            #include <stdio.h>
            #include <time.h>
            #include <wchar.h>
            #include <wctype.h>
            wctrans_t a;
          ]],
          [[]])],
       [gl_cv_type_wctrans_t=yes],
       [gl_cv_type_wctrans_t=no])
    ])
  if test $gl_cv_type_wctrans_t = no; then
    HAVE_WCTRANS_T=0
  fi

  dnl Check for declarations of anything we want to poison if the
  dnl corresponding gnulib module is not in use.
  gl_WARN_ON_USE_PREPARE([[
/* Tru64 with Desktop Toolkit C has a bug: <stdio.h> must be included before
   <wchar.h>.
   BSD/OS 4.0.1 has a bug: <stddef.h>, <stdio.h> and <time.h> must be
   included before <wchar.h>.  */
#if !(defined __GLIBC__ && !defined __UCLIBC__)
# include <stddef.h>
# include <stdio.h>
# include <time.h>
# include <wchar.h>
#endif
#include <wctype.h>
    ]],
    [wctype iswctype wctrans towctrans
    ])
])

AC_DEFUN([gl_WCTYPE_MODULE_INDICATOR],
[
  dnl Use AC_REQUIRE here, so that the default settings are expanded once only.
  AC_REQUIRE([gl_WCTYPE_H_DEFAULTS])
  gl_MODULE_INDICATOR_SET_VARIABLE([$1])
  dnl Define it also as a C macro, for the benefit of the unit tests.
  gl_MODULE_INDICATOR_FOR_TESTS([$1])
])

AC_DEFUN([gl_WCTYPE_H_DEFAULTS],
[
  GNULIB_ISWBLANK=0;    AC_SUBST([GNULIB_ISWBLANK])
  GNULIB_WCTYPE=0;      AC_SUBST([GNULIB_WCTYPE])
  GNULIB_ISWCTYPE=0;    AC_SUBST([GNULIB_ISWCTYPE])
  GNULIB_WCTRANS=0;     AC_SUBST([GNULIB_WCTRANS])
  GNULIB_TOWCTRANS=0;   AC_SUBST([GNULIB_TOWCTRANS])
  dnl Assume proper GNU behavior unless another module says otherwise.
  HAVE_ISWBLANK=1;      AC_SUBST([HAVE_ISWBLANK])
  HAVE_WCTYPE_T=1;      AC_SUBST([HAVE_WCTYPE_T])
  HAVE_WCTRANS_T=1;     AC_SUBST([HAVE_WCTRANS_T])
  REPLACE_ISWBLANK=0;   AC_SUBST([REPLACE_ISWBLANK])
])