Re: emacsclient: support `/' directory separator on w32

[Lennart Borgman <lennart.borgman.073@student.lu.se>]

David Kastrup wrote:
> Lennart Borgman <lennart.borgman.073@student.lu.se> writes:
> 
>> Eli Zaretskii wrote:
>>>> Date: Wed, 29 Nov 2006 01:51:51 +0100
>>>> From: Lennart Borgman <lennart.borgman.073@student.lu.se>
>>>> Cc: emacs-devel@gnu.org
>>>>
>>>> I am not quite sure, but I believe I have seen that the
>>>> recommendation from MS for a file argument is to use
>>>> GetFullPathName.
>>> But Emacs does not do it, see expand-file-name.  So your proposed
>>> changes make emacsclient behave differently than Emacs.
>>
>> What is the reason that Emacs does not do it?
> 
> Emacs stores its idea of "relativeness" in `default-directory', a
> buffer-local variable.
> 
> It is not clear how one would attempt to model drive-relativeness on
> different drives than the one the buffer is in.  It is possible to
> make `default-directory' point to a different drive from that of
> `buffer-file-name'.  Maintaining the old drive-relative position at
> the same time does not seem possible to do in a reasonably predictable
> way.


I also thought so at first. At a second thought it seems simple. Just 
set emacs working directory (on w32) at the same time as setting 
default-directory. Then GetFullPathName will always return a result that 
is consistent with default-directory.

However the glory details of coding this in emacs is not something I 
precisely know immediately how to do ;-)

And setting the working directory makes me a bit scared too. But is the 
working directory ever used in emacs? (I found one call to 
get_current_directory_name in smc_save_yourself.)


Some more trouble: You can ask emacs to edit a file with a name like 
d:/somepath/c:hello.txt. The characters

    \/:*?"<>|

are not allowed in the last part of a file or directory name on w32. 
(Actually using a file name with ":" in the name is possible, but it 
does not do what an innocent user expect. It creates a file with a 
hidden what-did-they-call-it? part.)

Unfortunately GetLongPathName() does not care about these characters. I 
therefore tried with GetLongPathName(), but I could not link with MingGW:

   oo-spd/i386/emacsclient.o(.text+0x283b):emacsclient.c:
      undefined reference to `GetLongPathName'

Maybe there is a better API for checking file names?