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Date: Tue, 2 Jun 2009 15:46:21 +0200
From: Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
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Subject: Re: [1.7] Surprising exe magic?
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On May 24 20:49, Dave Korn wrote:
> admin AT ubik /tmp/exemagic
> $ mv hello.x hello.test.x
> 
> admin AT ubik /tmp/exemagic
> $ ls -la
> total 125
> drwxr-xr-x 1 DKAdmin None     0 May 24 20:36 .
> drwxrwxrwt 1 DKAdmin None 90112 May 24 20:36 ..
> -rwxr-xr-x 1 DKAdmin None 34326 May 24 20:36 hello.test.x.exe
> -rw-r--r-- 1 DKAdmin None   121 May 24 20:36 hw.c
> 
>   I expect this is probably one of those things that there's no way to avoid
> without breaking some far more common usage, perhaps?  It's not that bad since
> it still runs as expected, and you can rename it again explicitly to get the
> name you really wanted:
> 
> $ ./hello.test.x
> Hello, .exe magic!
> 
> admin AT ubik /tmp/exemagic
> $ ls
> hello.test.x.exe  hw.c
> 
> admin AT ubik /tmp/exemagic
> $ mv hello.test.x.exe hello.test.x
> 
> admin AT ubik /tmp/exemagic
> $ ls
> hello.test.x  hw.c
> 
> ... but I found it a bit surprising.  Is it supposed to happen like this?  I
> had a look in the recent announcement posts, and in /usr/share/doc, and
> couldn't find much explicit documentation about how exe magic works, but I
> noted that mv doesn't support `--disable-exe-magic'.

Have a look into the rename() routine.  It's really tricky to get the
.exe magic right when renaming a file.  Every time I change it, another
case crops up which doesn't quite work as expected.  Take strip(1)
for example.  It strips a file by creating a temporary file without
.exe suffix.  It writes the stripped executable into it, then it renames
the temp file back to the original file.

Call `strip foo' on a file actually called foo.exe.  Without .exe magic
you end up with a file foo, which is kind of surprising.  You expect that
the resulting file is still called foo.exe, and that will work with the
current implementation.

However, other cases might not *quite* work as expected as you found out.

P's are really, really welcome.


Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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