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# unlink.m4 serial 14
dnl Copyright (C) 2009-2020 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.
AC_DEFUN([gl_FUNC_UNLINK],
[
AC_REQUIRE([gl_UNISTD_H_DEFAULTS])
AC_REQUIRE([AC_CANONICAL_HOST])
AC_CHECK_HEADERS_ONCE([unistd.h])
dnl Detect FreeBSD 7.2, AIX 7.1, Solaris 9 bug.
AC_CACHE_CHECK([whether unlink honors trailing slashes],
[gl_cv_func_unlink_honors_slashes],
[touch conftest.file
# Assume that if we have lstat, we can also check symlinks.
if test $ac_cv_func_lstat = yes; then
ln -s conftest.file conftest.lnk
fi
AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[[#if HAVE_UNISTD_H
# include <unistd.h>
#else /* on Windows with MSVC */
# include <io.h>
#endif
#include <errno.h>
]],
[[int result = 0;
if (!unlink ("conftest.file/"))
result |= 1;
else if (errno != ENOTDIR)
result |= 2;
#if HAVE_LSTAT
if (!unlink ("conftest.lnk/"))
result |= 4;
else if (errno != ENOTDIR)
result |= 8;
#endif
return result;
]])],
[gl_cv_func_unlink_honors_slashes=yes],
[gl_cv_func_unlink_honors_slashes=no],
[case "$host_os" in
# Guess yes on Linux systems.
linux-* | linux) gl_cv_func_unlink_honors_slashes="guessing yes" ;;
# Guess yes on glibc systems.
*-gnu*) gl_cv_func_unlink_honors_slashes="guessing yes" ;;
# Guess no on native Windows.
mingw*) gl_cv_func_unlink_honors_slashes="guessing no" ;;
# If we don't know, obey --enable-cross-guesses.
*) gl_cv_func_unlink_honors_slashes="$gl_cross_guess_normal" ;;
esac
])
rm -f conftest.file conftest.lnk])
case "$gl_cv_func_unlink_honors_slashes" in
*no)
REPLACE_UNLINK=1
;;
esac
dnl Detect Mac OS X 10.5.6 bug: On read-write HFS mounts, unlink("..") or
dnl unlink("../..") succeeds without doing anything.
AC_CACHE_CHECK([whether unlink of a parent directory fails as it should],
[gl_cv_func_unlink_parent_fails],
[case "$host_os" in
darwin*)
dnl Try to unlink a subdirectory of /tmp, because /tmp is usually on a
dnl HFS mount on Mac OS X. Use a subdirectory, owned by the current
dnl user, because otherwise unlink() may fail due to permissions
dnl reasons, and because when running as root we don't want to risk
dnl destroying the entire /tmp.
if {
# Use the mktemp program if available. If not available, hide the error
# message.
tmp=`(umask 077 && mktemp -d /tmp/gtXXXXXX) 2>/dev/null` &&
test -n "$tmp" && test -d "$tmp"
} ||
{
# Use a simple mkdir command. It is guaranteed to fail if the directory
# already exists. $RANDOM is bash specific and expands to empty in shells
# other than bash, ksh and zsh. Its use does not increase security;
# rather, it minimizes the probability of failure in a very cluttered /tmp
# directory.
tmp=/tmp/gt$$-$RANDOM
(umask 077 && mkdir "$tmp")
}; then
mkdir "$tmp/subdir"
GL_SUBDIR_FOR_UNLINK="$tmp/subdir"
export GL_SUBDIR_FOR_UNLINK
AC_RUN_IFELSE(
[AC_LANG_SOURCE([[
#include <stdlib.h>
#if HAVE_UNISTD_H
# include <unistd.h>
#else /* on Windows with MSVC */
# include <direct.h>
# include <io.h>
#endif
int main ()
{
int result = 0;
if (chdir (getenv ("GL_SUBDIR_FOR_UNLINK")) != 0)
result |= 1;
else if (unlink ("..") == 0)
result |= 2;
return result;
}
]])],
[gl_cv_func_unlink_parent_fails=yes],
[gl_cv_func_unlink_parent_fails=no],
[# If we don't know, obey --enable-cross-guesses.
gl_cv_func_unlink_parent_fails="$gl_cross_guess_normal"
])
unset GL_SUBDIR_FOR_UNLINK
rm -rf "$tmp"
else
gl_cv_func_unlink_parent_fails="guessing no"
fi
;;
*)
gl_cv_func_unlink_parent_fails="guessing yes"
;;
esac
])
case "$gl_cv_func_unlink_parent_fails" in
*no)
REPLACE_UNLINK=1
AC_DEFINE([UNLINK_PARENT_BUG], [1],
[Define to 1 if unlink() on a parent directory may succeed])
;;
esac
])
|
