Directory existence prevents .exe execution

[Larry Hall (Cygwin)]

On 04/18/2008, Luke Kendall wrote:
> Larry Hall (Cygwin) wrote: What do you mean by Cygwin, in this case?
> Bash?  Cygwin's implementation of exec()?

In this case, bash.  Try it from, say, csh, and you'll see something a
bit different.

>> It uses stat() to find out what type of thing "foo" is.  Then it uses
>> that information to decide how to handle "foo".
>> 
> This is why I'm saying that something that handles the invocation of 
> programs under Cygwin tries to execute directories:
> 
> $ /opt/bin/ici -help bash: /opt/bin/ici: is a directory $ whiches ici 
> /opt/bin/ici.exe /opt/bin/ici.dll /cygdrive/x/bin/ici.exe 
> /cygdrive/x/bin/ici.dll $ ls -ld /opt/bin/Ici drwxr-xr-x 1 luke Domain
> Users 0 Oct 17  2005 /opt/bin/Ici
> 
> It looks like something has stat()ed /opt/bin/ici and then decided it's 
> been asked to execute that, and refusing (which makes a kind of sense),
> and bailing out with an error (*that* step seems wrong to me).

Well, didn't you ask to execute '/opt/bin/ici'?  After all, that's what you
typed.  I don't see how it could be wrong to report back what you asked to
execute is a directory.

> I assumed that the logic which invokes foo.exe when you type foo should 
> not be trying to execute a directory called foo.  It's never right to 
> try to execute a directory.

True enough.  Hence the message.  The directory isn't being executed here.

> I'm suggesting that instead of trying to do that and reporting an error 
> and failing, the code should just skip past that as obviously wrong and 
> fall through to the rest of its logic, which would in fact do the right 
> thing - even if the foo.exe was in some other directory entirely, later 
> on the PATH!

If you ask for 'foo' or '/path/to/foo' and that's a directory, going beyond
that looking for something else when you've found an exact match is a bit
dangerous.  You don't want to be taking too many liberties with the exe
magic.  Things could get ugly fast.  That said, if you want an executable
to be named "foo" and not "foo.exe", you can do that on NT-based platforms.
But again, here you're back to a situation where you won't be able to have
a same-named directory right beside the executable.  But that matches *nix.


-- 
Larry Hall                              http://www.rfk.com
RFK Partners, Inc.                      (508) 893-9779 - RFK Office
216 Dalton Rd.                          (508) 893-9889 - FAX
Holliston, MA 01746

_____________________________________________________________________

A: Yes.
> Q: Are you sure?
>> A: Because it reverses the logical flow of conversation.
>>> Q: Why is top posting annoying in email?

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