Re: [Qemu-devel] [PATCH] Fix double backslash problem in Windows

[Anthony Liguori <anthony@codemonkey.ws>]

Laurent Vivier wrote:
> Le mercredi 09 janvier 2008 à 11:40 +0100, andrzej zaborowski a écrit :
>   
>> On 09/01/2008, Laurent Vivier <Laurent.Vivier@bull.net> wrote:
>>     
>>> Le mercredi 09 janvier 2008 à 10:31 +0100, Laurent Vivier a écrit :
>>>       
>>>> Le mardi 08 janvier 2008 à 17:17 +0100, Hervé Poussineau a écrit :
>>>>         
>>>>> Hi,
>>>>>
>>>>> On Windows, since December 2nd, files names provided in command line
>>>>> have to double their backslash to work correctly, for example: "-hda
>>>>> c:\\disks\\qemu.qcow" instead of -hda c:\disks\qemu.qcow"
>>>>> This patch removes this need and reverts back to Qemu 0.9.0 behaviour
>>>>>
>>>>> Hervé
>>>>>
>>>>>           
>>>> I have introduced this behavior to be able to use command line like
>>>> "qemu -hda my\ file", IMHO your patch should be #ifdef for window only.
>>>>         
>>> In fact, this is a wrong example, this case is managed by the shell.
>>> A good example is when we have a filename with a '"' in it:
>>>
>>> qemu -hda 2\\\"file
>>>
>>> to open file 2"file
>>>       
>> And the correct behaviour for that would be to open the file 2\"file, while
>>
>> qemu -hda 2\"file
>>
>> should open 2"file. The only character that we may need to handle
>> specially should be the comma, I don't know if anyone cares.
>>     
>
> You're right...
> but "-hda" is an alias for "-drive file="%s",index=%d,media=disk".
>
> So when you type "qemu -hda 2\"file",
> it becomes "qemu -drive file="2"file",index=0,media=disk"
> which gives filename equal to "2file,index=0,media=disk" instead of
> filename equal to 2"file with option index and media.
>   

The proper solution is to escape the files before doing the snprintf().

Regards,

Anthony Liguori

> So the '\' is needed, and you must have "qemu -hda 2\\\"file" to
> have "qemu -drive file="2\"file",index=0,media=disk" and then can
> extract filename to 2"file
>
> In the alias, file="%s" is needed to be able to manage filenames with
> spaces. for instance, if you don't have '"", you will have:
> qemu -hda "my file"
> -> qemu -drive file=my file,index=0,media=disk
> and thus filename is "my"...
>
>   
>> I mean, some characters do need special handling but reimplementing
>> full escaping logic like in the shell is imho not needed and leads to
>> typing things like \\\" and forces GUIs to learn the new rules too.
>> And doesn't justify making unix and ms-windows behaviour different.
>>     
>
> I totally agree with you, but I didn't find any other solution to manage
> this.
>
> Regards,
> Laurent
>