Eryk Sun <eryk...@gmail.com> added the comment:
> copystat() and copymode() should be able to copy the same > metadata/security-bits/etc as CopyFileExW. Regarding metadata, CopyFileExW copies the basic file info (i.e. FileAttributes, LastAccessTime, LastWriteTime, and ChangeTime). This metadata can be copied separately as the FileBasicInfo, via GetFileInformationByHandleEx and SetFileInformationByHandle. (Zero the CreationTime field to skip setting it.) Note that this includes the change time (i.e. Unix st_ctime) in file systems that support it, such as NTFS and ReFS. It also includes all settable file attributes, including readonly, hidden, system, archive, temporary, and not-content-indexed. Currently we only copy the readonly attribute. Regarding security bits, CopyFileExW copies security resource attributes (i.e. ATTRIBUTE_SECURITY_INFORMATION), which in Windows 8+ can be referenced by arbitrarily complex expressions in conditional ACEs. See "[MS-DTYP] 2.4.4.17 Conditional ACEs" [1] for details. Security resource attributes can be queried and set by handle via GetSecurityInfo and SetSecurityInfo. This information is set in the system access control list (SACL), but it does not require the privileged ACCESS_SYSTEM_SECURITY right. It only requires READ_CONTROL and WRITE_DAC access. CopyFileExW also copies extended attributes. These are commonly set on system files, but in this case they're usually "$Kernel." attributes [2], which cannot be set from user mode. IIRC, WSL also uses them. Otherwise extended attributes are not used much at all because the Windows API provides no way to query and set them separately. (They're supported in the NT API via NtQueryEaFile and NtSetEaFile.) When creating a new file via CreateFileW, we can pass it a handle to a template file from which to copy extended attributes. But that doesn't help with copystat(), which requires copying extended attributes onto an existing file. Regarding data, CopyFileExW copies all $DATA streams [3] in a file, not just the anonymous $DATA stream. The stream names and sizes can be read via GetFileInformationByHandleEx: FileStreamInfo. Just loop over the stream names to try copying them individually. For complete consistency, copytree should copy named data streams in directories. (A directory can't have an anonymous data stream, but it can have named streams, and it's not uncommon to store metadata about a directory like this. Ignoring this data is inconsistent, but it's a matter of opinion whether complete consistency is worthwhile.) This can be implemented at a high level via CreateDirectoryExW by passing the source directory path as the lpTemplateDirectory parameter. However, CreateDirectoryExW also preserves whether the directory is compressed or encrypted. I don't know whether copytree should preserve those attributes. [1] https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-dtyp/10dc22eb-788d-4343-b556-0b6969fe58ca [2] https://docs.microsoft.com/en-us/windows-hardware/drivers/ifs/kernel-extended-attributes [3] https://docs.microsoft.com/en-us/windows/win32/fileio/file-streams ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue38906> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
