On Sun, 24 Mar 2024 at 21:34, Björn Schäpers <g...@hazardy.de> wrote:
>
> From: Björn Schäpers <bjo...@hazardy.de>
>
> This fixes i.e. https://github.com/msys2/MSYS2-packages/issues/1937
> I don't know if I picked the right way to do it.
>
> When acceptable I think the declaration should be moved into
> ops-common.h, since then we could use stat_type and also use that in the
> commonly used function.
>
> Manually tested on i686-w64-mingw32.
>
> -- >8 --
> libstdc++: Fix overwriting files on windows
>
> The inodes have no meaning on windows, thus all files have an inode of
> 0. Use a differenz approach to identify equivalent files. As a result
> std::filesystem::copy_file did not honor
> copy_options::overwrite_existing. Factored the method out of
> std::filesystem::equivalent.
>
> libstdc++-v3/Changelog:
>
> * include/bits/fs_ops.h: Add declaration of
> __detail::equivalent_win32.
> * src/c++17/fs_ops.cc (__detail::equivalent_win32): Implement it
> (fs::equivalent): Use __detail::equivalent_win32, factored the
> old test out.
> * src/filesystem/ops-common.h (_GLIBCXX_FILESYSTEM_IS_WINDOWS):
> Use the function.
>
> Signed-off-by: Björn Schäpers <bjo...@hazardy.de>
> ---
> libstdc++-v3/include/bits/fs_ops.h | 8 +++
> libstdc++-v3/src/c++17/fs_ops.cc | 79 +++++++++++++-----------
> libstdc++-v3/src/filesystem/ops-common.h | 10 ++-
> 3 files changed, 60 insertions(+), 37 deletions(-)
>
> diff --git a/libstdc++-v3/include/bits/fs_ops.h
> b/libstdc++-v3/include/bits/fs_ops.h
> index 90650c47b46..d10b78a4bdd 100644
> --- a/libstdc++-v3/include/bits/fs_ops.h
> +++ b/libstdc++-v3/include/bits/fs_ops.h
> @@ -40,6 +40,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
> namespace filesystem
> {
> +#ifdef _GLIBCXX_FILESYSTEM_IS_WINDOWS
> +namespace __detail
> +{
> + bool
> + equivalent_win32(const wchar_t* p1, const wchar_t* p2, error_code& ec);
I don't think we want this declared in the public header, it should be
internal to the library.
Can it just be declared in ops-common.h instead?
> +} // namespace __detail
> +#endif //_GLIBCXX_FILESYSTEM_IS_WINDOWS
> +
> /** @addtogroup filesystem
> * @{
> */
> diff --git a/libstdc++-v3/src/c++17/fs_ops.cc
> b/libstdc++-v3/src/c++17/fs_ops.cc
> index 61df19753ef..3cc87d45237 100644
> --- a/libstdc++-v3/src/c++17/fs_ops.cc
> +++ b/libstdc++-v3/src/c++17/fs_ops.cc
> @@ -67,6 +67,49 @@
> namespace fs = std::filesystem;
> namespace posix = std::filesystem::__gnu_posix;
>
> +#ifdef _GLIBCXX_FILESYSTEM_IS_WINDOWS
> +bool
> +fs::__detail::equivalent_win32(const wchar_t* p1, const wchar_t* p2,
> + error_code& ec)
> +{
> + 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);
This creates a new filesystem::path, just to call c_str() on it
immediately. The auto_handle ctor should be changed to just take const
wchar_t* so we don't need to allocate and parse new path objects.
> + auto_handle h2(p2);
> + if (!h1 || !h2)
> + {
> + if (!h1 && !h2)
> + ec = __last_system_error();
> + return false;
> + }
> + if (!h1.get_info() || !h2.get_info())
> + {
> + ec = __last_system_error();
> + return false;
> + }
> + return h1.info.dwVolumeSerialNumber == h2.info.dwVolumeSerialNumber
> + && h1.info.nFileIndexHigh == h2.info.nFileIndexHigh
> + && h1.info.nFileIndexLow == h2.info.nFileIndexLow;
> +}
> +#endif //_GLIBCXX_FILESYSTEM_IS_WINDOWS
> +
> fs::path
> fs::absolute(const path& p)
> {
> @@ -858,41 +901,7 @@ 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);
> - if (!h1 || !h2)
> - {
> - if (!h1 && !h2)
> - ec = __last_system_error();
> - return false;
> - }
> - if (!h1.get_info() || !h2.get_info())
> - {
> - ec = __last_system_error();
> - return false;
> - }
> - return h1.info.dwVolumeSerialNumber == h2.info.dwVolumeSerialNumber
> - && h1.info.nFileIndexHigh == h2.info.nFileIndexHigh
> - && h1.info.nFileIndexLow == h2.info.nFileIndexLow;
> + return __detail::equivalent_win32(p1.c_str(), p2.c_str(), ec);
> #else
> return st1.st_dev == st2.st_dev && st1.st_ino == st2.st_ino;
> #endif
> diff --git a/libstdc++-v3/src/filesystem/ops-common.h
> b/libstdc++-v3/src/filesystem/ops-common.h
> index d917fddbeb1..7e67286bd01 100644
> --- a/libstdc++-v3/src/filesystem/ops-common.h
> +++ b/libstdc++-v3/src/filesystem/ops-common.h
> @@ -489,8 +489,14 @@ _GLIBCXX_BEGIN_NAMESPACE_FILESYSTEM
> return false;
> }
>
> - if (to_st->st_dev == from_st->st_dev
> - && to_st->st_ino == from_st->st_ino)
> +#ifdef _GLIBCXX_FILESYSTEM_IS_WINDOWS
> + // st_ino is not set, so can't be used to distinguish files
> + std::error_code not_used;
> + if (st1.st_mode != st2.st_mode || st1.st_dev != st2.st_dev ||
> + fs::__detail::equivalent_win32(from, to, not_used))
> +#else
> + if (st1.st_dev != st2.st_dev || st1.st_ino != st2.st_ino)
> +#endif
> {
> ec = std::make_error_code(std::errc::file_exists);
> return false;
> --
> 2.44.0
>
