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Re: [Patch] unlink
On Sat, Oct 30, 2004 at 10:30:54PM -0400, Pierre A. Humblet wrote:
>At 01:39 PM 10/30/2004 -0400, you wrote:
>>On Fri, Oct 29, 2004 at 06:01:51PM -0400, Pierre A. Humblet wrote:
>>>Here is a patch that should allow unlink() to handle
>>>nul etc.. on local disks.
>>>
>>>It's a cut and paste of Corinna's open on NT and the
>>>existing CreateFile.
>>>
>>>It works on normal files. I haven't tested with the
>>>special names because I forgot how to create them !
>>>Feedback welcome.
>>>
>>>XXXXX This should NOT be applied in 1.5.12 XXXXXX
>>>
>>>Pierre
>>>
>>>2004-10-29 Pierre Humblet <pierre.humblet@ieee.org>
>>>
>>> * syscalls.cc (nt_delete): New function.
>>> (unlink): Call nt_delete instead of CreateFile and remove
>>> unreachable code.
>>
>>Corinna suggested something similar to me a couple of months ago but I
>>wanted to wait for things to settle down somewhat after the original
>>use of NtCreateFile.
>>
>>On reflection, however, wouldn't it be a little easier just to prepend
>>the path being deleted with a: \\.\ so that "rm nul" would eventually
>>translate to DeleteFile("\\.\c:\foo\null") (I'm not using true C
>>backslash quoting here)? I don't know if that would work on Windows 9x,
>>though.
>
>That would work on NT, but then one would need to check if the input
>path didn't already have the form //./xx, worry about exceeding max
>pathlength, etc...
Other than being able to delete special filenames is there any other
benefit to using NtCreateFile to delete files?
If path length was an issue we could use '//?/' instead since the length
restriction is a lot larger there. So, it would be something like:
char *path;
char newpath[strlen (win32_name) + 4] = "\\\\?\";
if (win32_name[0] != '\\')
path = strcat (newpath, win32_name);
else
path = win32_name;
and then you'd use path throughout from then on.
We could use a technique like this for other things, like rename, to enable
it to manipulate accidentally-created special files.
OTOH, I just had an idea about how to use //?/ on NT so that we could
have longer path names. I have to mull it over a little to see if it
would work or not, though. I have an airplane trip tomorrow that would
be perfect for this kind of mulling.
cgf