Re: [Muscle] libmusclecard 1.3.x and yylex() endless loops

[Iain MacDonnell]

Karsten Ohme wrote on 03/15/06 07:08 PM:

Iain MacDonnell wrote:

I've run into a problem with two different applications that link to
libmusclecard. One of them is muscleTool-2.1.0, and the other is a
proprietary tool that's not OpenSource, but the symptom is the same -
ie. they both get stuck in an endless loop when trying to parse XML
files, during yylex().

Eg. When I run muscleTool and try to do "tokens", it "hangs":

blue-midget# /opt/ITmuscle/bin/muscleTool
MuscleCard shell - type "help" for help.
muscleTool > version
muscleTool version: 2.1.0
Copyright (C) 1998-2002 David Corcoran
Copyright (C) 2003 Ludovic Rousseau
Copyright (C) 2004 Toni Andjelkovic
Copyright (C) 2005 Karsten Ohme
muscleTool > tokens


I can see that the stack trace is:

 08053b29 yylex    (8047dbc, d1faab44, d1fbb170, d1fa7158, d1fbc16c,
d1fa9daf) + 545
 d1fa9e79 LTPBundleFindValueWithKey (8047225, d1fbc16c, 8047063, 0) + d9
 d1fa7158 TPSearchBundlesForAtr (804759c, 9, 804737c) + 198
 d1fa2e42 MSCListTokens (1, 0, 806fff8, 126) + 272
 08055258 doListTokens (d1e987b4, c, 1d, 27, 8047634, 8047962) + 49
 08052e78 yyparse  (d1fca0e0, d1ffb314, d1ffb840, 8047c38, 0, 6373756d)
+ 717
 080535ce main     (1, 8047d60, 8047d68) + 12e
 08052604 _start   (1, 8047e24, 0, 8047e41, 8047e60, 8047e6b) + 80


The other application also hangs during yylex() (different type of XML
file being parsed at the time).

In both cases, if I point them at an old libmusclecard.so from
1.2.9-beta7, the problem goes away. I did notice that the older library
(which I didn't build - someone gave me the binary) is linked to
'libl.so' - the Solaris lex library, but my v1.3.x version is not. I
tried forcing it by adding LEXLIB to LIBS in the Makefile, but it didn't
help the actual problem - ie. the endless loop still occurs.

Could this have something do to with the visibility changes? I'm a bit
flummoxed by it... :(

Actually the visibility changes should fix this. And at least on my
Debian they did. There was a problem with the lex parser of muscleTool
and the lexx stuff to parse the XML Info.plist from libmusclecard. I
thought it had something to do with newer gcc versions, because it was
working in former times, but a real reason would be interesting.
Use the tool objdump or nm or whatever to see the exported symbols of
the library. Maybe this can help.

Yeah, I was just thinking along these lines, after sending that message.
I looked at the source for libmusclecard 1.2.9-beta7, and notice that it
does not have a tokenparser.l, so perhaps a new use of (f)lex was added
in a later version, and now that's somehow overriding the parser in
muscleTool (but not doing its job).

I think that visibility works (or doesn't work) differently with the
Sun compilers (vs. gcc). Maybe Dr. Ludovic can shed some light on this...

Thanks...

    ~Iain



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