Re: [4/11] Native MSVC support (file-magic-glob)

[Charles Wilson]

Peter Rosin wrote:
>         * libltdl/m4/libtool.m4 (_LT_CHECK_MAGIC_METHOD),
>         libltdl/config/ltmain.m4sh (func_mode_link): On Windows,
>         find potential libs regardless of file name case.

Hmm.  Well, this one might pose some problems.  On cygwin, there exists 
something called "managed mounts" where cygwin transmogrifies all 
filenames (using RFC2396 encoding -- see 
http://www.rfc-editor.org/rfc/rfc2396.txt section 2.4) to work around 
the limitations of Windows' filesystems.

In particular, it allows you to have distinct files in the same 
directory whose names differ only in case.  e.g.

FOO.a ==> %46%4F%4F.a
Foo.a ==> %46oo.a
foo.a ==> foo.a

(If you look at the directory using a non-cygwin app, the files are 
actually names as they appear in the right hand column above)

If managed mounts are in use, and some idiot actually has libraries like 
this [*], what does -lfoo mean?  With this patch, it seems a bit -- 
well, not really random, but non-intuitive and unpredictable to the 
casual user.   Whichever of FOO.a, Foo.a, or foo.a is returned first by 
the shell glob -- which may differ depending on $SHELL and the 
underlying glob implementation[**] -- is the one you get.

OTOH, this may be a case of "Doctor, it hurts when I do this", "OK, 
don't do that then": don't be stupid when naming distinct libraries.  If 
you insist on being stupid, we can't help you.

In fact, I rather lean toward this approach -- and to accepting Peter's 
patch in principle. There is such a thing as being TOO defensive when 
programming.



As to implementation...ye gods.  Turning every libname into

[lL][iI][bB][nN][aA][mM][eE]

by using this sed expr

s/[aA]/[aA]/g;s/[bB]/[bB]/g;<22 more>;s/[yY]/[yY]/g;s/[zZ]/[zZ]/g;

Isn't there a better way? (I can't think of one offhand, given how this 
is used to generate a list of "potential_libs", but still...this can't 
be very efficient.)

--
Chuck

[*] on my generic linux box,
ls -1 /usr/lib | tr '[:lower:]' '[:upper:]' | sort | uniq -d
has no hits.  So linux isn't stupid.

[**] the cygwin kernel's glob -- which may or may not be used by $SHELL 
-- in CVS HEAD was changed a while back, so behavior under 
snapshots/1.7.0 *may* differ from current cygwin 1.5.24.


> +               if test -n "$file_magic_glob"; then
> +                 libnameglob=`$ECHO "X$libname" | $Xsed -e $file_magic_glob`
> +               else
> +                 libnameglob=$libname
> +               fi
>                 for i in $lib_search_path $sys_lib_search_path 
> $shlib_search_path; do
> -                 potential_libs=`ls $i/$libname[.-]* 2>/dev/null`
> +                 potential_libs=`ls $i/$libnameglob[.-]* 2>/dev/null`
>                   for potent_lib in $potential_libs; do


> +case $host_os in
> +cygwin* | mingw* | pw32*)
> +  file_magic_glob=`echo aAbBcCdDeEfFgGhHiIjJkKlLmMnNoOpPqQrRsStTuUvVwWxXyYzZ | $SED -e 
> "s/\(..\)/s\/[[\1]]\/[[\1]]\/g;/g"`
> +  ;;
> +*)
> +  file_magic_glob=
> +  ;;