std::filesystem::hard_link_count() always returns 1 on mingw-w64ucrt-11.0.1-r3 on Windows 10 19045
hard_link_count() queries _wstat64() on MinGW-w64 The MSFT documentation claims _wstat64() will always return 1 *non*-NTFS volumes https://learn.microsoft.com/en-us/previous-versions/visualstudio/visual-studio-2013/14h5k7ff(v=vs.120) My tests suggest that is not always true - hard_link_count()/_wstat64() still returns 1 on NTFS. GetFileInformationByHandle does return the correct result of 2. Please see the PR for a minimal repro. This patch changes the Windows implementation to always call GetFileInformationByHandle. Ran the libstdc++-v3/testsuite on x86_64-pc-linux-gnu and x86_64-pc-cygwin. Performed manual testing on x86_64-w64-mingw32. This is my first GCC contribution attempt. Please call out any omissions or mistakes. Thanks. PR target/113663 libstdc++-v3/ChangeLog: * src/c++17/fs_ops.cc (fs::equivalent): Moved helper class auto_handle to anonymous namespace as auto_win_file_handle. (fs::hard_link_count): Changed Windows implementation to use information provided by GetFileInformationByHandle which is more reliable. * testsuite/27_io/filesystem/operations/hard_link_count.cc: New test. Signed-off-by: "Lennox" Shou Hao Ho <lennox...@gmail.com> --- libstdc++-v3/src/c++17/fs_ops.cc | 59 ++++++++++++------- .../filesystem/operations/hard_link_count.cc | 54 +++++++++++++++++ 2 files changed, 91 insertions(+), 22 deletions(-) create mode 100644 libstdc++-v3/testsuite/27_io/filesystem/operations/hard_link_count.cc diff --git a/libstdc++-v3/src/c++17/fs_ops.cc b/libstdc++-v3/src/c++17/fs_ops.cc index 61df19753ef..eec3d86590f 100644 --- a/libstdc++-v3/src/c++17/fs_ops.cc +++ b/libstdc++-v3/src/c++17/fs_ops.cc @@ -822,6 +822,31 @@ fs::equivalent(const path& p1, const path& p2) return result; } +#if _GLIBCXX_FILESYSTEM_IS_WINDOWS +namespace +{ + struct auto_win_file_handle { + explicit auto_win_file_handle(const fs::path& p_) + : handle(CreateFileW(p_.c_str(), 0, + FILE_SHARE_DELETE | FILE_SHARE_READ | FILE_SHARE_WRITE, + 0, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, 0)) + { } + + ~auto_win_file_handle() + { if (*this) CloseHandle(handle); } + + explicit operator bool() const + { return handle != INVALID_HANDLE_VALUE; } + + bool get_info() + { return GetFileInformationByHandle(handle, &info); } + + HANDLE handle; + BY_HANDLE_FILE_INFORMATION info; + }; +} +#endif + bool fs::equivalent(const path& p1, const path& p2, error_code& ec) noexcept { @@ -858,27 +883,8 @@ fs::equivalent(const path& p1, const path& p2, error_code& ec) noexcept if (st1.st_mode != st2.st_mode || st1.st_dev != st2.st_dev) return false; - struct auto_handle { - explicit auto_handle(const path& p_) - : handle(CreateFileW(p_.c_str(), 0, - FILE_SHARE_DELETE | FILE_SHARE_READ | FILE_SHARE_WRITE, - 0, OPEN_EXISTING, FILE_FLAG_BACKUP_SEMANTICS, 0)) - { } - - ~auto_handle() - { if (*this) CloseHandle(handle); } - - explicit operator bool() const - { return handle != INVALID_HANDLE_VALUE; } - - bool get_info() - { return GetFileInformationByHandle(handle, &info); } - - HANDLE handle; - BY_HANDLE_FILE_INFORMATION info; - }; - auto_handle h1(p1); - auto_handle h2(p2); + auto_win_file_handle h1(p1); + auto_win_file_handle h2(p2); if (!h1 || !h2) { if (!h1 && !h2) @@ -982,7 +988,16 @@ fs::hard_link_count(const path& p) std::uintmax_t fs::hard_link_count(const path& p, error_code& ec) noexcept { -#ifdef _GLIBCXX_HAVE_SYS_STAT_H +#if _GLIBCXX_FILESYSTEM_IS_WINDOWS + auto_win_file_handle h(p); + if (h && h.get_info()) + { + return static_cast<uintmax_t>(h.info.nNumberOfLinks); + } + + ec = __last_system_error(); + return static_cast<uintmax_t>(-1); +#elif defined(_GLIBCXX_HAVE_SYS_STAT_H) return do_stat(p, ec, std::mem_fn(&stat_type::st_nlink), static_cast<uintmax_t>(-1)); #else diff --git a/libstdc++-v3/testsuite/27_io/filesystem/operations/hard_link_count.cc b/libstdc++-v3/testsuite/27_io/filesystem/operations/hard_link_count.cc new file mode 100644 index 00000000000..5acba96aa82 --- /dev/null +++ b/libstdc++-v3/testsuite/27_io/filesystem/operations/hard_link_count.cc @@ -0,0 +1,54 @@ +// Copyright (C) 2019-2024 Free Software Foundation, Inc. +// +// This file is part of the GNU ISO C++ Library. This library is free +// software; you can redistribute it and/or modify it under the +// terms of the GNU General Public License as published by the +// Free Software Foundation; either version 3, or (at your option) +// any later version. + +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License along +// with this library; see the file COPYING3. If not see +// <http://www.gnu.org/licenses/>. + +// { dg-do run { target c++17 } } +// { dg-require-filesystem-ts "" } + +#include <filesystem> +#include <testsuite_hooks.h> +#include <testsuite_fs.h> + +namespace fs = std::filesystem; + +void test01() +{ + // PR libstdc++/113663 + + fs::path p1 = __gnu_test::nonexistent_path(); + VERIFY( !fs::exists(p1) ); + + __gnu_test::scoped_file f1(p1); + VERIFY( fs::exists(p1) ); + + VERIFY( fs::hard_link_count(p1) == 1 ); + + fs::path p2 = __gnu_test::nonexistent_path(); + VERIFY( !fs::exists(p2) ); + + fs::create_hard_link(p1, p2); + __gnu_test::scoped_file f2(p2, __gnu_test::scoped_file::adopt_file); + VERIFY( fs::exists(p2) ); + + VERIFY( fs::hard_link_count(p1) == 2 ); + VERIFY( fs::hard_link_count(p2) == 2 ); +} + +int +main() +{ + test01(); +} -- 2.34.1