Eryk Sun schreef op 28/05/2020 om 15:51:
On 5/27/20, Chris Angelico <ros...@gmail.com> wrote:
On Thu, May 28, 2020 at 7:07 AM BlindAnagram <blindanag...@nowhere.com>
wrote:
You can define a path however you want but it won't change the fact that
on Windows a path that ends in '\\' is inherently a path to a directory.
Citation needed.
See [MS-FSA] 2.1.5.1 Server Requests an Open of a File [1]. Here are
the relevant statements:
The operation MUST be failed with STATUS_OBJECT_NAME_INVALID under
any of the following conditions:
....
* If PathName contains a trailing backslash and
CreateOptions.FILE_NON_DIRECTORY_FILE is TRUE.
i.e. trailing backslashes are not allowed for regular files
....
If PathName contains a trailing backslash:
* If StreamTypeToOpen is DataStream or
CreateOptions.FILE_NON_DIRECTORY_FILE is TRUE, the operation MUST
be failed with STATUS_OBJECT_NAME_INVALID
i.e. again, trailing backslashes are not allowed for non-directory files.
There is no limitation listed that says something like "The operation
must be failed if pathname doesn't contain a trailing backslash and
CreateOptions.FILE_NON_DIRECTOR_FILE is FALSE". Path names referring to
directories are allowed to have trailing backslashes, but no requirement
to do so. Directory PathNames with and without trailing backslashes are
handled exactly the same.
Internally, WinAPI CreateFileW calls NTAPI NtCreateFile with the
create option FILE_NON_DIRECTORY_FILE (i.e. only open or create a data
file stream), unless backup semantics are requested in order to be
able to open a directory (i.e. an index stream), in which case the
call uses neither FILE_NON_DIRECTORY_FILE nor FILE_DIRECTORY_FILE and
leaves it up to the path name.
No, that is not my understanding. It is up to the actual type of file
specified by the path. CreateFileW using FILE_FLAG_BACKUP_SEMANTICS can
only open existing directories, so there is no need to look at the last
character of the path.
In other words, with backup semantics, if you need to ensure that
only a directory is opened, add a trailing slash.
It's not like you have some random path, you think "hey, I only want to
open this if it is a directory", and then do
CreateFileW(
L"...\\...\\",
..,
...,
...,
...,
FILE_FLAG_BACKUP_SEMANTICS,
NULL);
What happens instead is that you have a path to a real existing object
(CreateFileW on directories works only with both OPEN_EXISTING and
FILE_FLAG_BACKUP_SEMANTICS specified: you can not create a directory
using CreateFileW), and CreateFileW (via NtCreateFile) will open it as a
directory if the object is a directory, and as a file it is a file.
Exception is that it will refuse to open it as a file if there's a
backslash in the end, while for directories backslashes are optional.
But if you never add a backslash in the end, everything will work just
fine for both files and directories.
--
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friend, an acquaintance, or a stranger."
-- Franklin P. Jones
Roel Schroeven
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