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# fchownat.m4 serial 5
dnl Copyright (C) 2004-2020 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.
# Written by Jim Meyering.
# If we have the fchownat function, and it has the bug (in glibc-2.4)
# that it dereferences symlinks even with AT_SYMLINK_NOFOLLOW, then
# use the replacement function.
# Also if the fchownat function, like chown, has the trailing slash bug,
# use the replacement function.
# Also use the replacement function if fchownat is simply not available.
AC_DEFUN([gl_FUNC_FCHOWNAT],
[
AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
AC_REQUIRE([gl_FUNC_CHOWN])
AC_CHECK_FUNC([fchownat],
[gl_FUNC_FCHOWNAT_DEREF_BUG(
[REPLACE_FCHOWNAT=1
AC_DEFINE([FCHOWNAT_NOFOLLOW_BUG], [1],
[Define to 1 if your platform has fchownat, but it cannot
perform lchown tasks.])
])
gl_FUNC_FCHOWNAT_EMPTY_FILENAME_BUG(
[REPLACE_FCHOWNAT=1
AC_DEFINE([FCHOWNAT_EMPTY_FILENAME_BUG], [1],
[Define to 1 if your platform has fchownat, but it does
not reject an empty file name.])
])
if test $REPLACE_CHOWN = 1; then
REPLACE_FCHOWNAT=1
fi],
[HAVE_FCHOWNAT=0])
])
# gl_FUNC_FCHOWNAT_DEREF_BUG([ACTION-IF-BUGGY[, ACTION-IF-NOT_BUGGY]])
AC_DEFUN([gl_FUNC_FCHOWNAT_DEREF_BUG],
[
dnl Persuade glibc's <unistd.h> to declare fchownat().
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
AC_CACHE_CHECK([whether fchownat works with AT_SYMLINK_NOFOLLOW],
[gl_cv_func_fchownat_nofollow_works],
[
gl_dangle=conftest.dangle
# Remove any remnants of a previous test.
rm -f $gl_dangle
# Arrange for deletion of the temporary file this test creates.
ac_clean_files="$ac_clean_files $gl_dangle"
ln -s conftest.no-such $gl_dangle
AC_RUN_IFELSE(
[AC_LANG_SOURCE(
[[
#include <fcntl.h>
#include <unistd.h>
/* Android 4.3 declares fchownat() in <sys/stat.h> instead. */
#include <sys/stat.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/types.h>
int
main ()
{
return (fchownat (AT_FDCWD, "$gl_dangle", -1, getgid (),
AT_SYMLINK_NOFOLLOW) != 0
&& errno == ENOENT);
}
]])],
[gl_cv_func_fchownat_nofollow_works=yes],
[gl_cv_func_fchownat_nofollow_works=no],
[gl_cv_func_fchownat_nofollow_works="$gl_cross_guess_normal"])
])
AS_IF([test "$gl_cv_func_fchownat_nofollow_works" != yes], [$1], [$2])
])
# gl_FUNC_FCHOWNAT_EMPTY_FILENAME_BUG([ACTION-IF-BUGGY[, ACTION-IF-NOT_BUGGY]])
AC_DEFUN([gl_FUNC_FCHOWNAT_EMPTY_FILENAME_BUG],
[
dnl Persuade glibc's <unistd.h> to declare fchownat().
AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
AC_CACHE_CHECK([whether fchownat works with an empty file name],
[gl_cv_func_fchownat_empty_filename_works],
[AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[[#include <unistd.h>
#include <fcntl.h>
/* Android 4.3 declares fchownat() in <sys/stat.h> instead. */
#include <sys/stat.h>
]],
[[int fd;
int ret;
if (mkdir ("conftestdir", 0700) < 0)
return 2;
fd = open ("conftestdir", O_RDONLY);
if (fd < 0)
return 3;
ret = fchownat (fd, "", -1, -1, 0);
close (fd);
rmdir ("conftestdir");
return ret == 0;
]])],
[gl_cv_func_fchownat_empty_filename_works=yes],
[gl_cv_func_fchownat_empty_filename_works=no],
[gl_cv_func_fchownat_empty_filename_works="$gl_cross_guess_normal"])
])
AS_IF([test "$gl_cv_func_fchownat_empty_filename_works" != yes], [$1], [$2])
])
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