[CMake] cmake -E create_symlink for Windows

[Hendrik Sattler]

Zitat von Michael Wild <themiwi at gmail.com>:
> On 11. Dec, 2009, at 15:17 , Hendrik Sattler wrote:
>> Zitat von Michael Wild <themiwi at gmail.com>:
>>> On 11. Dec, 2009, at 14:27 , Marcel Loose wrote:
>>>> I was browsing the CMake sources for a problem I was facing with the
>>>> creation of symlinks (on Unix that is) and I noticed that the
>>>> SystemTools::CreateSymlink function simply returns false when building
>>>> on a Windows platform.
>>>>
>>>> Does that mean that I cannot use 'cmake -E create_symlink' on Windows.
>>>> If that's the case I consider it a bug, because the documentation
>>>> suggests that 'cmake -E create_symlink' provides a platform independent
>>>> way of creating symbolic links. So, if the OS and/or filesystem does not
>>>> support symbolic links, IMHO, it should just copy the file.
>>>
>>> Simply copying the file might be just as bad if people assume it    
>>> really IS a symlink... IMHO, if the OS can't create a symlink,   
>>> cmake  -E create_symlink should fail loudly, not just silently   
>>> ignore it.  And somebody should implement this function for   
>>> Windows >=  Vista/2008 (i.e. WINVER >= 0x0600):
>>>
>>> http://msdn.microsoft.com/en-us/library/aa363866(VS.85).aspx
>>
>> For this, also see
>>  http://schinagl.priv.at/nt/hardlinkshellext/hardlinkshellext.html
>> Please note the UAC dialog when creating symlink on Vista. Have   
>> fun, I'd say :-(
>>
>> And what do you do on WindowsXP? What to do on FAT filesystems?
>> Additionally, without that extension above, it is non-obvious for   
>> Windows users that a specific file is a symbolic link.
>
> The UAC-thing only applies to directories where the user has no   
> write-acces (including the admin), right? So if you're half-way   
> sane, and build in a user-owned directory, you should be UAC-free...

To cite from that page:
  Vista and UAC

One of the major Vista changes was the so called User Account Control  
(UAC). Due to UAC some API calls need elevation to administrative  
level, and this elevation must be acknowledged via the below shown  
dialog box. Unfortunately, and I still can't believe this, the API  
call CreateSymbolicLink is a call, which needs elevation, and thus  
causes this annoying dialog box come up every time a symbolic link is  
created.


So, no, every time, even on own directories. I don't currently use  
Vista or Windows7, though. Also read the rest of that part of the  
page: cmake should not use functions directly that need elevation.

HS

PS: added list back