From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from rock.gnat.com (rock.gnat.com [205.232.38.15]) by sourceware.org (Postfix) with ESMTPS id 2522B3856DE7; Thu, 23 Jun 2022 11:08:26 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 2522B3856DE7 Received: from localhost (localhost.localdomain [127.0.0.1]) by filtered-rock.gnat.com (Postfix) with ESMTP id BA8311161BE; Thu, 23 Jun 2022 07:08:25 -0400 (EDT) X-Virus-Scanned: Debian amavisd-new at gnat.com Received: from rock.gnat.com ([127.0.0.1]) by localhost (rock.gnat.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id YTcHLphMiaXT; Thu, 23 Jun 2022 07:08:25 -0400 (EDT) Received: from free.home (tron.gnat.com [IPv6:2620:20:4000:0:46a8:42ff:fe0e:e294]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by rock.gnat.com (Postfix) with ESMTPS id 807361161BD; Thu, 23 Jun 2022 07:08:25 -0400 (EDT) Received: from livre (livre.home [172.31.160.2]) by free.home (8.15.2/8.15.2) with ESMTPS id 25NB8Hwi762263 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 23 Jun 2022 08:08:17 -0300 From: Alexandre Oliva To: Jonathan Wakely Cc: gcc Patches , "libstdc++" Subject: Re: [PATCH] libstdc++-v3: check for openat Organization: Free thinker, does not speak for AdaCore References: Errors-To: aoliva@lxoliva.fsfla.org Date: Thu, 23 Jun 2022 08:08:17 -0300 In-Reply-To: (Jonathan Wakely's message of "Wed, 22 Jun 2022 11:36:17 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.84 X-Spam-Status: No, score=-12.3 required=5.0 tests=BAYES_00, GIT_PATCH_0, KAM_DMARC_STATUS, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: libstdc++@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libstdc++ mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 23 Jun 2022 11:08:27 -0000 On Jun 22, 2022, Jonathan Wakely wrote: > There are other interactions between AT_CDCWD and ::openat not covered > by this patch. I this this also needs to check HAVE_OPENAT: Here's an updated version, tested with this additional change. libstdc++: check for openat From: Alexandre Oliva 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. * aclocal.m4, 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. --- libstdc++-v3/acinclude.m4 | 12 +++++++ libstdc++-v3/config.h.in | 3 ++ libstdc++-v3/configure | 55 ++++++++++++++++++++++++++++++ libstdc++-v3/src/filesystem/dir-common.h | 2 + libstdc++-v3/src/filesystem/dir.cc | 2 + 5 files changed, 72 insertions(+), 2 deletions(-) diff --git a/libstdc++-v3/acinclude.m4 b/libstdc++-v3/acinclude.m4 index 138bd58d86cb9..e3cc3a8e867d3 100644 --- a/libstdc++-v3/acinclude.m4 +++ b/libstdc++-v3/acinclude.m4 @@ -4772,6 +4772,18 @@ dnl if test $glibcxx_cv_dirfd = yes; then AC_DEFINE(HAVE_DIRFD, 1, [Define if dirfd is available in .]) fi +dnl + AC_CACHE_CHECK([for openat], + glibcxx_cv_openat, [dnl + GCC_TRY_COMPILE_OR_LINK( + [#include ], + [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 .]) + fi dnl AC_CACHE_CHECK([for unlinkat], glibcxx_cv_unlinkat, [dnl diff --git a/libstdc++-v3/config.h.in b/libstdc++-v3/config.h.in index f30a8c51c458c..2a3972eef5412 100644 --- a/libstdc++-v3/config.h.in +++ b/libstdc++-v3/config.h.in @@ -292,6 +292,9 @@ /* Define if defines obsolete isnan function. */ #undef HAVE_OBSOLETE_ISNAN +/* Define if openat is available in . */ +#undef HAVE_OPENAT + /* Define if poll is available in . */ #undef HAVE_POLL diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure index 9b94fd71e4248..eac6039212168 100755 --- a/libstdc++-v3/configure +++ b/libstdc++-v3/configure @@ -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.$ac_ext +/* end confdefs.h. */ +#include +int +main () +{ +int fd = ::openat(AT_FDCWD, "", 0); + ; + return 0; +} +_ACEOF +if ac_fn_cxx_try_compile "$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.$ac_ext +/* end confdefs.h. */ +#include +int +main () +{ +int fd = ::openat(AT_FDCWD, "", 0); + ; + return 0; +} +_ACEOF +if ac_fn_cxx_try_link "$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; } diff --git a/libstdc++-v3/src/filesystem/dir-common.h b/libstdc++-v3/src/filesystem/dir-common.h index 365fd527f4d68..669780ea23fe5 100644 --- a/libstdc++-v3/src/filesystem/dir-common.h +++ b/libstdc++-v3/src/filesystem/dir-common.h @@ -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 diff --git a/libstdc++-v3/src/filesystem/dir.cc b/libstdc++-v3/src/filesystem/dir.cc index b451902c4a1b1..e64489162e5ff 100644 --- a/libstdc++-v3/src/filesystem/dir.cc +++ b/libstdc++-v3/src/filesystem/dir.cc @@ -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()}; -- Alexandre Oliva, happy hacker https://FSFLA.org/blogs/lxo/ Free Software Activist GNU Toolchain Engineer Disinformation flourishes because many people care deeply about injustice but very few check the facts. 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