Am 27.10.24 um 16:38 schrieb Patrick Steinhardt:

On Sun, Oct 27, 2024 at 02:23:28PM +0100, Johannes Sixt wrote:

quoted

Am 24.10.24 um 13:46 schrieb Patrick Steinhardt:

quoted

Windows 10 has introduced the `FILE_RENAME_FLAG_POSIX_SEMANTICS` flag
that allows us to fix this usecase [1]. When set, it is possible to
rename a file over a preexisting file even when the target file still
has handles open. Those handles must have been opened with the
`FILE_SHARE_DELETE` flag, which we have ensured in the preceding
commits.

quoted

Careful readers might have noticed that [1] does not mention the above

flag, but instead mentions `FILE_RENAME_POSIX_SEMANTICS`. This flag is
not for use with `SetFileInformationByHandle()` though, which is what we
use. And while the `FILE_RENAME_FLAG_POSIX_SEMANTICS` flag exists, it is
not documented on [2] or anywhere else as far as I can tell.

The Windows 10 SDK defines FILE_RENAME_FLAG_REPLACE_IF_EXISTS and
FILE_RENAME_FLAG_POSIX_SEMANTICS for SetFileInformationByHandle(). That
the documentation lacks "_FLAG_" in the names must be an error in the
documentation.

I found the mention of FILE_RENAME_POSIX_SEMANTICS quite distracting,
because it is a flag to be used with CreateFileW() and basically only
has to do with case-sensitivity, but nothing with POSIX semantics of
renaming.

I'd still prefer to mention this, because otherwise an astute reader
might notice that I'm using a different flag name than what is
documented in the docs and figure out that I defined the wrong flag
name.

Ah, I was confused twice here. First, the documentation that you cite[*]
mentions FILE_RENAME_POSIX_SEMANTICS, but the name does not exist at
all. There does exist FILE_RENAME_FLAG_POSIX_SEMANTICS. The
documentation is just wrong. And in my earlier comment I copied the
inexistent flag name.

But I meant to cite this flag: FILE_FLAG_POSIX_SEMANTICS (no "RENAME").
It exists and is for CreateFileW().

Perhaps you also meant cite the latter one as the flag that "is not for
use with `SetFileInformationByHandle()`"?

At any rate, the paragraph as written isn't correct.

[1]:
https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/ntifs/ns-ntifs-_file_rename_information

-- Hannes