bug#13414: Valid DLL def file mangled by libtool

[Peter Rosin]

Hi Martin,

Thanks for the report.

On 2013-01-11 12:34, Martin Doucha wrote:
> Hi,
> I'd like to report a bug in libtool 2.4 (including the latest git revision) 
> which mangles valid DLL def files under MinGW and makes the linker barf.
> 
> The bug is caused by incorect check for "EXPORTS" keyword in the def file 
> which libtool does this way:
> if test "x`$SED 1q $export_symbols`" != xEXPORTS; then ... [add another 
> "EXPORTS" line at the beginning of file]
> 
> This test is incorrect because the "EXPORTS" keyword does not have to appear 
> on the very first line. You should replace the test with this:
> if test "x`$GREP EXPORTS $export_symbols`" != xEXPORTS; then ...
> 
> Also note that this test appears on several places throughout libtool sources 
> (both as "xEXPORTS" and just "EXPORTS") so you need to fix all of them.

This issue has been reported before [1].

It's been on my back burner for a while, but I've been held up by
build system issues. At least, that's my excuse :-)

Anyway, I think your suggested alternative with grep is a bit too
relaxed, as any symbol involving the substring "EXPORTS" would
trigger it. Also, it scans the whole file, which is suboptimal.

I'm looking into a patch that uses

        $SED -n \
            -e '/^[     ]*//' \
            -e '/^;/D' \
            -e '/^$/D' \
            -e 's/^EXPORTS.*/DEF/p' \
            -e 's/^LIBRARY.*/DEF/p' \
            -e q \
            $export_symbols

instead (coupled with a test for "DEF" instead, naturally). Does
anybody have any issues with such a beast? Yes, I know that it
will not catch any valid .def file, but I don't fancy writing a
full .def file parser for this [2].

The above steps past initial comment and whitespace lines waiting
for the first "real" line, and triggers if it starts with EXPORTS
or LIBRARY (at least, that's the intention...)

[1] http://lists.gnu.org/archive/html/libtool/2012-02/msg00023.html
[2] http://msdn.microsoft.com/en-us/library/h41zhe21(v=vs.110).aspx

Cheers,
Peter