[PATCH] Handle Windows nul device in unlink-if-ordinary.c

[Jeff Law]

On 3/12/23 23:15, Himal wrote:
> On 3/12/2023 1:48 AM, Jeff Law wrote:
>>
>>
>> On 1/6/23 01:31, anothername27-unity--- via Gcc-patches wrote:
>>> From: Himal <himalr@proton.me>
>>>
>>> Hi,
>>>
>>> This might be a better fix.
>>>
>>> Regards.
>>>
>>> PS. I had to use a different email.
>>>
>>> ---
>>>   libiberty/unlink-if-ordinary.c | 6 ++++++
>>>   1 file changed, 6 insertions(+)
>>>
>>> diff --git a/libiberty/unlink-if-ordinary.c 
>>> b/libiberty/unlink-if-ordinary.c
>>> index 84328b216..e765ac8b1 100644
>>> --- a/libiberty/unlink-if-ordinary.c
>>> +++ b/libiberty/unlink-if-ordinary.c
>>> @@ -62,6 +62,12 @@ was made to unlink the file because it is special.
>>>   int
>>>   unlink_if_ordinary (const char *name)
>>>   {
>>> +/* MS-Windows 'stat' function (and in turn, S_ISREG)
>>> +   reports the null device as a regular file.  */
>>> +#ifdef _WIN32
>>> +  if (stricmp (name, "nul") == 0)
>>> +    return 1;
>>> +#endif
> 
> Hi Jeff, Thanks for the response.
> 
>> Umm, wouldn't this return true for a real file called nul in the 
>> current directory?  ie, don't you need to distinguish between the nul 
>> device and a file named nul based on the full path?
> 
> I don't think that we can create a file called nul under Windows.
> 
>> And not being a windows person, I'd really like to see some 
>> documentation which indicates that stat on the null device will 
>> indicate its a regular file.  Alternately if one of the windows 
>> experts here can chime in, it'd be appreciated.
>> jeff
> 
> I found these patches that might indicate the same thing.
> 
> https://src.fedoraproject.org/rpms/binutils/blob/0b119dd9d51a3763db7d6fea1b51a03494cb96d8/f/binutils-CVE-2021-20197.patch#_121-135
> 
> https://github.com/msys2/MINGW-packages/pull/10541/files
> 
> I would like to see some input from a Windows developer as well.
> 
> BTW, This doesn't affecting anything. I stumbled upon this while 
> debugging another 
> [bug](https://sourceware.org/bugzilla/show_bug.cgi?id=29947). I noticed 
> it's calling unlink function for the nul device as well, but it wasn't 
> throwing any errors or anything like that.
I'm inclined to go ahead and commit this.  I think the only other 
question I have is the use of stricmp.  That's not strictly ISO, 
strcasecmp would be preferred.  But I don't know enough about the 
windows environment to know if they picked up strcasecmp over time.

jeff