Re: [PATCH] Fix overwriting files with fs::copy_file on windows

[One of your IPs tried to hack me <spam@hazardy.de>]

Am 25.04.2024 um 22:16 schrieb Björn Schäpers:
> Am 24.03.2024 um 22:34 schrieb Björn Schäpers:
>> From: Björn Schäpers <bjoern@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 <bjoern@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);
>> +} // 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);
>> +  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;
> 
> A friendly ping.

Ping.