| 1 | # fcntl.m4 serial 5
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| 2 | dnl Copyright (C) 2009-2012 Free Software Foundation, Inc.
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| 3 | dnl This file is free software; the Free Software Foundation
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| 4 | dnl gives unlimited permission to copy and/or distribute it,
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| 5 | dnl with or without modifications, as long as this notice is preserved.
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| 6 |
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| 7 | # For now, this module ensures that fcntl()
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| 8 | # - supports F_DUPFD correctly
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| 9 | # - supports or emulates F_DUPFD_CLOEXEC
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| 10 | # - supports F_GETFD
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| 11 | # Still to be ported to mingw:
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| 12 | # - F_SETFD
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| 13 | # - F_GETFL, F_SETFL
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| 14 | # - F_GETOWN, F_SETOWN
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| 15 | # - F_GETLK, F_SETLK, F_SETLKW
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| 16 | AC_DEFUN([gl_FUNC_FCNTL],
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| 17 | [
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| 18 | dnl Persuade glibc to expose F_DUPFD_CLOEXEC.
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| 19 | AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
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| 20 | AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
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| 21 | AC_REQUIRE([AC_CANONICAL_HOST])
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| 22 | AC_CHECK_FUNCS_ONCE([fcntl])
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| 23 | if test $ac_cv_func_fcntl = no; then
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| 24 | gl_REPLACE_FCNTL
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| 25 | else
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| 26 | dnl cygwin 1.5.x F_DUPFD has wrong errno, and allows negative target
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| 27 | dnl haiku alpha 2 F_DUPFD has wrong errno
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| 28 | AC_CACHE_CHECK([whether fcntl handles F_DUPFD correctly],
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| 29 | [gl_cv_func_fcntl_f_dupfd_works],
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| 30 | [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
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| 31 | #include <fcntl.h>
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| 32 | #include <errno.h>
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| 33 | ]], [[int result = 0;
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| 34 | if (fcntl (0, F_DUPFD, -1) != -1) result |= 1;
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| 35 | if (errno != EINVAL) result |= 2;
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| 36 | return result;
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| 37 | ]])],
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| 38 | [gl_cv_func_fcntl_f_dupfd_works=yes],
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| 39 | [gl_cv_func_fcntl_f_dupfd_works=no],
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| 40 | [# Guess that it works on glibc systems
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| 41 | case $host_os in #((
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| 42 | *-gnu*) gl_cv_func_fcntl_f_dupfd_works="guessing yes";;
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| 43 | *) gl_cv_func_fcntl_f_dupfd_works="guessing no";;
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| 44 | esac])])
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| 45 | case $gl_cv_func_fcntl_f_dupfd_works in
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| 46 | *yes) ;;
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| 47 | *) gl_REPLACE_FCNTL
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| 48 | AC_DEFINE([FCNTL_DUPFD_BUGGY], [1], [Define this to 1 if F_DUPFD
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| 49 | behavior does not match POSIX]) ;;
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| 50 | esac
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| 51 |
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| 52 | dnl Many systems lack F_DUPFD_CLOEXEC
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| 53 | AC_CACHE_CHECK([whether fcntl understands F_DUPFD_CLOEXEC],
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| 54 | [gl_cv_func_fcntl_f_dupfd_cloexec],
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| 55 | [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
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| 56 | #include <fcntl.h>
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| 57 | #ifndef F_DUPFD_CLOEXEC
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| 58 | choke me
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| 59 | #endif
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| 60 | ]])],
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| 61 | [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
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| 62 | #ifdef __linux__
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| 63 | /* The Linux kernel only added F_DUPFD_CLOEXEC in 2.6.24, so we always replace
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| 64 | it to support the semantics on older kernels that failed with EINVAL. */
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| 65 | choke me
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| 66 | #endif
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| 67 | ]])],
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| 68 | [gl_cv_func_fcntl_f_dupfd_cloexec=yes],
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| 69 | [gl_cv_func_fcntl_f_dupfd_cloexec="needs runtime check"])],
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| 70 | [gl_cv_func_fcntl_f_dupfd_cloexec=no])])
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| 71 | if test "$gl_cv_func_fcntl_f_dupfd_cloexec" != yes; then
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| 72 | gl_REPLACE_FCNTL
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| 73 | dnl No witness macro needed for this bug.
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| 74 | fi
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| 75 | fi
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| 76 | dnl Replace fcntl() for supporting the gnulib-defined fchdir() function,
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| 77 | dnl to keep fchdir's bookkeeping up-to-date.
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| 78 | m4_ifdef([gl_FUNC_FCHDIR], [
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| 79 | gl_TEST_FCHDIR
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| 80 | if test $HAVE_FCHDIR = 0; then
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| 81 | gl_REPLACE_FCNTL
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| 82 | fi
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| 83 | ])
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| 84 | ])
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| 85 |
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| 86 | AC_DEFUN([gl_REPLACE_FCNTL],
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| 87 | [
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| 88 | AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
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| 89 | AC_CHECK_FUNCS_ONCE([fcntl])
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| 90 | if test $ac_cv_func_fcntl = no; then
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| 91 | HAVE_FCNTL=0
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| 92 | else
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| 93 | REPLACE_FCNTL=1
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| 94 | fi
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| 95 | ])
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