[Caml-list] Ocaml and Samba function name collisions

[Caml-list] Ocaml and Samba function name collisions

[Blair Zajac]

Hello,

The synopsis of this message is to ask that the Ocaml source
code prepend a Ocaml specific string, "ml_", "caml_" or "ocaml_"
to all function names in Ocaml's source code to avoid name
collisions with other packages.  My case is made below :)

I'm using mod_caml and mod_smbauth in an Apache 1 process.
mod_smbauth is used to authenticate access to the web server
using our ActiveDirectory server.

http://www.tekrat.com/smbauth.php

When mod_caml.so is enabled in Apache httpd's conf file, it
core dumps with this stack backtrace:

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 1075767456 (LWP 3544)]
0x40b8a9cc in string_init (dest=0x40cb146c, src=0x1 <Address 0x1
out of bounds>) at lib/util_str.c:1142
1142      l = strlen(src);
(gdb) bt
#0  0x40b8a9cc in string_init (dest=0x40cb146c, src=0x1
<Address 0x1 out of bounds>) at lib/util_str.c:1142
#1  0x40b8ab21 in string_set (dest=0x1, src=0x0) at lib/util_str.c:1187
#2  0x40c34a4e in interprete () from
/opt/i386-linux/installed/apache-1.3.29-g/libexec/mod_caml.so
#3  0x40c265b1 in caml_main () from
/opt/i386-linux/installed/apache-1.3.29-g/libexec/mod_caml.so
#4  0x40c22ff4 in init () at mod_caml_c.c:80
#5  0x40c36975 in __do_global_ctors_aux () from
/opt/i386-linux/installed/apache-1.3.29-g/libexec/mod_caml.so
#6  0x40c20b95 in _init () from
/opt/i386-linux/installed/apache-1.3.29-g/libexec/mod_caml.so
...

Looking at the function names, both the Samba library and the
Ocaml source code have a function named string_set.  It's odd
though that the function name is binding to the Samba function
in mod_smbauth.so instead of the name in mod_caml.so, but then
I'm not an expert in shared library binding.

% nm mod_caml.so | grep string_set
00019846 T string_set
% nm mod_smbauth.so | grep string_set
00052afe T string_set
000552f9 T string_set_w

Now this may be a bug that can be worked around, but given
Ocaml's popularity in being linked with other packages, it
seems like a good idea to put all the Ocaml names into their
own space via a prepend.

I'd be happy to do some of this work by submitting patches to
the appropriate people/mailing list for review.  Let me know.

Best,
Blair

-- 
Blair Zajac <blair@orcaware.com>
Plots of your system's performance - http://www.orcaware.com/orca/

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Re: [Caml-list] Ocaml and Samba function name collisions

[Stefano Zacchiroli]

On Mon, Nov 24, 2003 at 04:31:24PM -0800, Blair Zajac wrote:
> The synopsis of this message is to ask that the Ocaml source
> code prepend a Ocaml specific string, "ml_", "caml_" or "ocaml_"
> to all function names in Ocaml's source code to avoid name
> collisions with other packages.  My case is made below :)

I will definitely sign this petition. I had a similar problem while
trying to write an ocaml binding to the graphviz library. Both the
libraries defined, IIRC, a color struct used in graphviz for node colors
and in ocaml by the GC :-(

Cheers.

-- 
^Stefano Zacchiroli -- Master in Computer Science @ Uni. Bologna, Italy$
^zack@{cs.unibo.it,debian.org,bononia.it} -- http://www.bononia.it/zack$
^Frequentando il mio maestro mi ero reso conto [.] che la logica poteva$
^servire a molto a condizione di entrarci dentro e poi di uscirne -Adso$

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Re: [Caml-list] Ocaml and Samba function name collisions

[Nicolas Cannasse]

> > The synopsis of this message is to ask that the Ocaml source
> > code prepend a Ocaml specific string, "ml_", "caml_" or "ocaml_"
> > to all function names in Ocaml's source code to avoid name
> > collisions with other packages.  My case is made below :)
>
> I will definitely sign this petition. I had a similar problem while
> trying to write an ocaml binding to the graphviz library. Both the
> libraries defined, IIRC, a color struct used in graphviz for node colors
> and in ocaml by the GC :-(

This is not a primitive name problem, but a data structure one (when
including file).
It can be easily resolved by using a #define color caml_color (or the
working equivalent) before including the caml headers.
Other solution is to put the caml headers into a C++ namespace.
BTW I'm not signing this petition : having everything prefixed with caml_ is
way to heavy. But for theses string_get string_set primitives that's true
the naming is too much generic and proper to name collision. Only theses
kinds should be renamed.

Nicolas Cannasse

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Re: [Caml-list] Ocaml and Samba function name collisions

[Samuel Mimram]

We've had recently exactly the same problem with libsmbclient (we even posted it here but no one seemed to have noticed it). The only solution we found yet was to modify the source code of libsmbclient to rename the colliding names (string_set and sys_open). But this is clearly not a good solution.

The #define you suggested does not seem to work and I think this is beacause they are not exported in the header files but are in the the .so and therefore visible in the global C namespace. And I'd prefer not to have to use C++ (I think I should be able to do it in C), so I did not try the namspace trick.

That's why, unless someone has a canonical solution to the problem, I think functions with such common names should have their names prefixed.


Samuel Mimram.


On Tue, 25 Nov 2003 16:52:22 +0900
"Nicolas Cannasse" <warplayer@free.fr> wrote:

> > > The synopsis of this message is to ask that the Ocaml source
> > > code prepend a Ocaml specific string, "ml_", "caml_" or "ocaml_"
> > > to all function names in Ocaml's source code to avoid name
> > > collisions with other packages.  My case is made below :)
> >
> > I will definitely sign this petition. I had a similar problem while
> > trying to write an ocaml binding to the graphviz library. Both the
> > libraries defined, IIRC, a color struct used in graphviz for node colors
> > and in ocaml by the GC :-(
> 
> This is not a primitive name problem, but a data structure one (when
> including file).
> It can be easily resolved by using a #define color caml_color (or the
> working equivalent) before including the caml headers.
> Other solution is to put the caml headers into a C++ namespace.
> BTW I'm not signing this petition : having everything prefixed with caml_ is
> way to heavy. But for theses string_get string_set primitives that's true
> the naming is too much generic and proper to name collision. Only theses
> kinds should be renamed.
> 
> Nicolas Cannasse
> 
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-- 
Samuel Mimram

samuel.mimram@ens-lyon.fr

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Re: [Caml-list] Ocaml and Samba function name collisions

[Nicolas Cannasse]

> The #define you suggested does not seem to work and
> I think this is beacause they are not exported in the header
> files but are in the the .so and therefore visible in the global
> C namespace. And I'd prefer not to have to use C++ (I think
> I should be able to do it in C), so I did not try the namspace trick.

This trick was an answer to Stephano problem about the struct color defined
by the camlheaders (if I understood correcly). I'm not sure there is a
workaround for the dl primitives name collisions which does not require the
modification of one of the two dlls.

Nicolas Cannasse

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Re: [Caml-list] Ocaml and Samba function name collisions

[Blair Zajac]

Nicolas Cannasse wrote:
> 
> > The #define you suggested does not seem to work and
> > I think this is beacause they are not exported in the header
> > files but are in the the .so and therefore visible in the global
> > C namespace. And I'd prefer not to have to use C++ (I think
> > I should be able to do it in C), so I did not try the namspace trick.
> 
> This trick was an answer to Stephano problem about the struct color defined
> by the camlheaders (if I understood correcly). I'm not sure there is a
> workaround for the dl primitives name collisions which does not require the
> modification of one of the two dlls.

I agree.  I don't think there's a workaround for this.

As getting patches and/or commit access to the Ocaml CVS tree is not
easy, I'm thinking of setting up a web page for patches to the official
Ocaml distrubtition.  I think this would be good for several reasons:

1) Anybody can submit then and they can be reviewed by the community.
   This would generate good quality patches.

2) The patches would be online in an easily accessible place when a
   Ocaml CVS committer wants to include them into the official
   distribution.  This could be done before a new Ocaml release,
   although patches should be applied to CVS as soon as possible
   to make the patching easier (less conflicts) and to test the code.

3) All patches would be in one location.

I've got two patches I would want in, the first for fixing this
function naming issue, the second free()ing some memory to avoid
a valgrind warning.

Best,
Blair

-- 
Blair Zajac <blair@orcaware.com>
Plots of your system's performance - http://www.orcaware.com/orca/

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Re: [Caml-list] Ocaml and Samba function name collisions

[Richard Jones]

On Tue, Nov 25, 2003 at 08:38:25AM +0100, Stefano Zacchiroli wrote:
> On Mon, Nov 24, 2003 at 04:31:24PM -0800, Blair Zajac wrote:
> > The synopsis of this message is to ask that the Ocaml source
> > code prepend a Ocaml specific string, "ml_", "caml_" or "ocaml_"
> > to all function names in Ocaml's source code to avoid name
> > collisions with other packages.  My case is made below :)
> 
> I will definitely sign this petition. I had a similar problem while
> trying to write an ocaml binding to the graphviz library. Both the
> libraries defined, IIRC, a color struct used in graphviz for node colors
> and in ocaml by the GC :-(

Ditto. Try linking caml with libperl some time. I did, and it's really
not pleasant. BOTH packages make claims on the whole namespace, and
there are conflicts.

Look at how tcl and tk use namespace some time for an example of how
to get this right.

Rich.

-- 
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