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libstdc++: check for openat 

rtems6.0 has fdopendir, and fcntl.h defines AT_FDCWD and declares
openat, but there's no openat in libc.  Adjust dir-common.h to not
assume ::openat just because of AT_FDCWD.


for  libstdc++-v3/ChangeLog

	* acinclude.m4 (GLIBCXX_CHECK_FILESYSTEM_DEPS): Check for
	openat.
	* configure, config.h.in: Rebuilt.
	* src/filesystem/dir-common.h (openat): Use ::openat if
	_GLIBCXX_HAVE_OPENAT.
	* src/filesystem/dir.cc (dir_and_pathname): Use dirfd if
	_GLIBCXX_HAVE_OPENAT.
This commit is contained in:
Alexandre Oliva 2022-06-23 23:20:53 -03:00 committed by Alexandre Oliva
parent 5d8a5f04ac
commit 93070671ea
5 changed files with 72 additions and 2 deletions
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12
libstdc++-v3/acinclude.m4
View File

@ -4772,6 +4772,18 @@ dnl
if test $glibcxx_cv_dirfd = yes; then
AC_DEFINE(HAVE_DIRFD, 1, [Define if dirfd is available in <dirent.h>.])
fi
dnl
AC_CACHE_CHECK([for openat],
glibcxx_cv_openat, [dnl
GCC_TRY_COMPILE_OR_LINK(
[#include <fcntl.h>],
[int fd = ::openat(AT_FDCWD, "", 0);],
[glibcxx_cv_openat=yes],
[glibcxx_cv_openat=no])
])
if test $glibcxx_cv_openat = yes; then
AC_DEFINE(HAVE_OPENAT, 1, [Define if openat is available in <fcntl.h>.])
fi
dnl
AC_CACHE_CHECK([for unlinkat],
glibcxx_cv_unlinkat, [dnl

3
libstdc++-v3/config.h.in
View File

@ -292,6 +292,9 @@
/* Define if <math.h> defines obsolete isnan function. */
#undef HAVE_OBSOLETE_ISNAN
/* Define if openat is available in <fcntl.h>. */
#undef HAVE_OPENAT
/* Define if poll is available in <poll.h>. */
#undef HAVE_POLL

55
libstdc++-v3/configure vendored
View File

@ -77177,6 +77177,61 @@ $as_echo "$glibcxx_cv_dirfd" >&6; }
$as_echo "#define HAVE_DIRFD 1" >>confdefs.h
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for openat" >&5
$as_echo_n "checking for openat... " >&6; }
if ${glibcxx_cv_openat+:} false; then :
$as_echo_n "(cached) " >&6
else
if test x$gcc_no_link = xyes; then
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <fcntl.h>
int
main ()
{
int fd = ::openat(AT_FDCWD, "", 0);
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
glibcxx_cv_openat=yes
else
glibcxx_cv_openat=no
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
else
if test x$gcc_no_link = xyes; then
as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5
fi
cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */
#include <fcntl.h>
int
main ()
{
int fd = ::openat(AT_FDCWD, "", 0);
;
return 0;
}
_ACEOF
if ac_fn_cxx_try_link "$LINENO"; then :
glibcxx_cv_openat=yes
else
glibcxx_cv_openat=no
fi
rm -f core conftest.err conftest.$ac_objext \
conftest$ac_exeext conftest.$ac_ext
fi
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $glibcxx_cv_openat" >&5
$as_echo "$glibcxx_cv_openat" >&6; }
if test $glibcxx_cv_openat = yes; then
$as_echo "#define HAVE_OPENAT 1" >>confdefs.h
fi
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for unlinkat" >&5
$as_echo_n "checking for unlinkat... " >&6; }

2
libstdc++-v3/src/filesystem/dir-common.h
View File

@ -199,7 +199,7 @@ struct _Dir_base
#endif
#ifdef AT_FDCWD
#if _GLIBCXX_HAVE_OPENAT && defined AT_FDCWD
fd = ::openat(fd, pathname, flags);
#else
// If we cannot use openat, there's no benefit to using posix::open unless

2
libstdc++-v3/src/filesystem/dir.cc
View File

@ -120,7 +120,7 @@ struct fs::_Dir : std::filesystem::_Dir_base
dir_and_pathname() const noexcept
{
const fs::path& p = entry.path();
#if _GLIBCXX_HAVE_DIRFD
#if _GLIBCXX_HAVE_DIRFD && _GLIBCXX_HAVE_OPENAT
return {::dirfd(this->dirp), std::prev(p.end())->c_str()};
#endif
return {this->fdcwd(), p.c_str()};