2 dnl Copyright (C) 2009-2018 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.
7 # For now, this module ensures that fcntl()
8 # - supports F_DUPFD correctly
9 # - supports or emulates F_DUPFD_CLOEXEC
11 # Still to be ported to mingw:
14 # - F_GETOWN, F_SETOWN
15 # - F_GETLK, F_SETLK, F_SETLKW
16 AC_DEFUN([gl_FUNC_FCNTL],
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
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],
35 #include <sys/resource.h>
37 #ifndef RLIM_SAVED_CUR
38 # define RLIM_SAVED_CUR RLIM_INFINITY
40 #ifndef RLIM_SAVED_MAX
41 # define RLIM_SAVED_MAX RLIM_INFINITY
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 */
60 fd = open (".", O_RDONLY);
63 else if (fcntl (fd, F_DUPFD, STDERR_FILENO + 1) == -1)
69 [gl_cv_func_fcntl_f_dupfd_works=yes],
70 [gl_cv_func_fcntl_f_dupfd_works=no],
72 aix* | cygwin* | haiku*)
73 gl_cv_func_fcntl_f_dupfd_works="guessing no" ;;
74 *) gl_cv_func_fcntl_f_dupfd_works="guessing yes" ;;
76 case $gl_cv_func_fcntl_f_dupfd_works in
79 AC_DEFINE([FCNTL_DUPFD_BUGGY], [1], [Define this to 1 if F_DUPFD
80 behavior does not match POSIX]) ;;
83 dnl Many systems lack F_DUPFD_CLOEXEC
84 AC_CACHE_CHECK([whether fcntl understands F_DUPFD_CLOEXEC],
85 [gl_cv_func_fcntl_f_dupfd_cloexec],
86 [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
88 #ifndef F_DUPFD_CLOEXEC
92 [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
94 /* The Linux kernel only added F_DUPFD_CLOEXEC in 2.6.24, so we always replace
95 it to support the semantics on older kernels that failed with EINVAL. */
99 [gl_cv_func_fcntl_f_dupfd_cloexec=yes],
100 [gl_cv_func_fcntl_f_dupfd_cloexec="needs runtime check"])],
101 [gl_cv_func_fcntl_f_dupfd_cloexec=no])])
102 if test "$gl_cv_func_fcntl_f_dupfd_cloexec" != yes; then
104 dnl No witness macro needed for this bug.
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], [
111 if test $HAVE_FCHDIR = 0; then
117 AC_DEFUN([gl_REPLACE_FCNTL],
119 AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
120 AC_CHECK_FUNCS_ONCE([fcntl])
121 if test $ac_cv_func_fcntl = no; then