1 # fcntl.m4 serial 5 2 dnl Copyright (C) 2009-2012 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([AC_LANG_PROGRAM([[ 31 #include <fcntl.h> 32 #include <errno.h> 33 ]], [[int result = 0; 34 if (fcntl (0, F_DUPFD, -1) != -1) result |= 1; 35 if (errno != EINVAL) result |= 2; 36 return result; 37 ]])], 38 [gl_cv_func_fcntl_f_dupfd_works=yes], 39 [gl_cv_func_fcntl_f_dupfd_works=no], 40 [# Guess that it works on glibc systems 41 case $host_os in #(( 42 *-gnu*) gl_cv_func_fcntl_f_dupfd_works="guessing yes";; 43 *) gl_cv_func_fcntl_f_dupfd_works="guessing no";; 44 esac])]) 45 case $gl_cv_func_fcntl_f_dupfd_works in 46 *yes) ;; 47 *) gl_REPLACE_FCNTL 48 AC_DEFINE([FCNTL_DUPFD_BUGGY], [1], [Define this to 1 if F_DUPFD 49 behavior does not match POSIX]) ;; 50 esac 51 52 dnl Many systems lack F_DUPFD_CLOEXEC 53 AC_CACHE_CHECK([whether fcntl understands F_DUPFD_CLOEXEC], 54 [gl_cv_func_fcntl_f_dupfd_cloexec], 55 [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ 56 #include <fcntl.h> 57 #ifndef F_DUPFD_CLOEXEC 58 choke me 59 #endif 60 ]])], 61 [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[ 62 #ifdef __linux__ 63 /* The Linux kernel only added F_DUPFD_CLOEXEC in 2.6.24, so we always replace 64 it to support the semantics on older kernels that failed with EINVAL. */ 65 choke me 66 #endif 67 ]])], 68 [gl_cv_func_fcntl_f_dupfd_cloexec=yes], 69 [gl_cv_func_fcntl_f_dupfd_cloexec="needs runtime check"])], 70 [gl_cv_func_fcntl_f_dupfd_cloexec=no])]) 71 if test "$gl_cv_func_fcntl_f_dupfd_cloexec" != yes; then 72 gl_REPLACE_FCNTL 73 dnl No witness macro needed for this bug. 74 fi 75 fi 76 dnl Replace fcntl() for supporting the gnulib-defined fchdir() function, 77 dnl to keep fchdir's bookkeeping up-to-date. 78 m4_ifdef([gl_FUNC_FCHDIR], [ 79 gl_TEST_FCHDIR 80 if test $HAVE_FCHDIR = 0; then 81 gl_REPLACE_FCNTL 82 fi 83 ]) 84 ]) 85 86 AC_DEFUN([gl_REPLACE_FCNTL], 87 [ 88 AC_REQUIRE([gl_FCNTL_H_DEFAULTS]) 89 AC_CHECK_FUNCS_ONCE([fcntl]) 90 if test $ac_cv_func_fcntl = no; then 91 HAVE_FCNTL=0 92 else 93 REPLACE_FCNTL=1 94 fi 95 ]) 96
