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-rw-r--r--m4/fcntl.m4126
1 files changed, 126 insertions, 0 deletions
diff --git a/m4/fcntl.m4 b/m4/fcntl.m4
new file mode 100644
index 0000000..e409e96
--- /dev/null
+++ b/m4/fcntl.m4
@@ -0,0 +1,126 @@
+# fcntl.m4 serial 9
+dnl Copyright (C) 2009-2019 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.
+
+# For now, this module ensures that fcntl()
+# - supports F_DUPFD correctly
+# - supports or emulates F_DUPFD_CLOEXEC
+# - supports F_GETFD
+# Still to be ported to mingw:
+# - F_SETFD
+# - F_GETFL, F_SETFL
+# - F_GETOWN, F_SETOWN
+# - F_GETLK, F_SETLK, F_SETLKW
+AC_DEFUN([gl_FUNC_FCNTL],
+[
+ dnl Persuade glibc to expose F_DUPFD_CLOEXEC.
+ AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
+ AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
+ AC_REQUIRE([AC_CANONICAL_HOST])
+ AC_CHECK_FUNCS_ONCE([fcntl])
+ if test $ac_cv_func_fcntl = no; then
+ gl_REPLACE_FCNTL
+ else
+ dnl cygwin 1.5.x F_DUPFD has wrong errno, and allows negative target
+ dnl haiku alpha 2 F_DUPFD has wrong errno
+ AC_CACHE_CHECK([whether fcntl handles F_DUPFD correctly],
+ [gl_cv_func_fcntl_f_dupfd_works],
+ [AC_RUN_IFELSE(
+ [AC_LANG_PROGRAM(
+ [[#include <errno.h>
+ #include <fcntl.h>
+ #include <limits.h>
+ #include <sys/resource.h>
+ #include <unistd.h>
+ #ifndef RLIM_SAVED_CUR
+ # define RLIM_SAVED_CUR RLIM_INFINITY
+ #endif
+ #ifndef RLIM_SAVED_MAX
+ # define RLIM_SAVED_MAX RLIM_INFINITY
+ #endif
+ ]],
+ [[int result = 0;
+ int bad_fd = INT_MAX;
+ struct rlimit rlim;
+ if (getrlimit (RLIMIT_NOFILE, &rlim) == 0
+ && 0 <= rlim.rlim_cur && rlim.rlim_cur <= INT_MAX
+ && rlim.rlim_cur != RLIM_INFINITY
+ && rlim.rlim_cur != RLIM_SAVED_MAX
+ && rlim.rlim_cur != RLIM_SAVED_CUR)
+ bad_fd = rlim.rlim_cur;
+ if (fcntl (0, F_DUPFD, -1) != -1) result |= 1;
+ if (errno != EINVAL) result |= 2;
+ if (fcntl (0, F_DUPFD, bad_fd) != -1) result |= 4;
+ if (errno != EINVAL) result |= 8;
+ /* On OS/2 kLIBC, F_DUPFD does not work on a directory fd */
+ {
+ int fd;
+ fd = open (".", O_RDONLY);
+ if (fd == -1)
+ result |= 16;
+ else if (fcntl (fd, F_DUPFD, STDERR_FILENO + 1) == -1)
+ result |= 32;
+
+ close (fd);
+ }
+ return result;]])],
+ [gl_cv_func_fcntl_f_dupfd_works=yes],
+ [gl_cv_func_fcntl_f_dupfd_works=no],
+ [case $host_os in
+ aix* | cygwin* | haiku*)
+ gl_cv_func_fcntl_f_dupfd_works="guessing no" ;;
+ *) gl_cv_func_fcntl_f_dupfd_works="guessing yes" ;;
+ esac])])
+ case $gl_cv_func_fcntl_f_dupfd_works in
+ *yes) ;;
+ *) gl_REPLACE_FCNTL
+ AC_DEFINE([FCNTL_DUPFD_BUGGY], [1], [Define this to 1 if F_DUPFD
+ behavior does not match POSIX]) ;;
+ esac
+
+ dnl Many systems lack F_DUPFD_CLOEXEC
+ AC_CACHE_CHECK([whether fcntl understands F_DUPFD_CLOEXEC],
+ [gl_cv_func_fcntl_f_dupfd_cloexec],
+ [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+#include <fcntl.h>
+#ifndef F_DUPFD_CLOEXEC
+choke me
+#endif
+ ]])],
+ [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+#ifdef __linux__
+/* The Linux kernel only added F_DUPFD_CLOEXEC in 2.6.24, so we always replace
+ it to support the semantics on older kernels that failed with EINVAL. */
+choke me
+#endif
+ ]])],
+ [gl_cv_func_fcntl_f_dupfd_cloexec=yes],
+ [gl_cv_func_fcntl_f_dupfd_cloexec="needs runtime check"])],
+ [gl_cv_func_fcntl_f_dupfd_cloexec=no])])
+ if test "$gl_cv_func_fcntl_f_dupfd_cloexec" != yes; then
+ gl_REPLACE_FCNTL
+ dnl No witness macro needed for this bug.
+ fi
+ fi
+ dnl Replace fcntl() for supporting the gnulib-defined fchdir() function,
+ dnl to keep fchdir's bookkeeping up-to-date.
+ m4_ifdef([gl_FUNC_FCHDIR], [
+ gl_TEST_FCHDIR
+ if test $HAVE_FCHDIR = 0; then
+ gl_REPLACE_FCNTL
+ fi
+ ])
+])
+
+AC_DEFUN([gl_REPLACE_FCNTL],
+[
+ AC_REQUIRE([gl_FCNTL_H_DEFAULTS])
+ AC_CHECK_FUNCS_ONCE([fcntl])
+ if test $ac_cv_func_fcntl = no; then
+ HAVE_FCNTL=0
+ else
+ REPLACE_FCNTL=1
+ fi
+])