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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
>>>2004-10-29  Pierre Humblet <>
>>>	* (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,
>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);
      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.


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