Re: [Caml-list] Problem native dynlink loading cryptokit

[Maxence Guesdon <Maxence.Guesdon@inria.fr>]

On Fri, 09 Aug 2013 11:43:53 +0200
Stéphane Glondu <steph@glondu.net> wrote:

> Le 09/08/2013 11:33, Maxence Guesdon a écrit :
> >>> Here is a test program:
> >>> [...]
> >>> gives me the following error:
> >>>
> >>> Fatal error: exception Failure("error loading shared
> >>> library: /home/guesdon/.opam/4.00.1/lib/cryptokit/cryptokit.cmxs:
> >>> undefined symbol: caml_sha1_init")
> >>>
> >>> Am I doing something wrong ? Or is something missing in cryptokit
> >>> build ?
> >>
> >> It works for me (with system packages).
> >>
> >> caml_sha1_init should be in cryptokit.cmxs. The output of
> >>
> >>   objdump -j .text -T /path/to/cryptokit.cmxs
> >>
> >> should contain all the C functions defined in cryptokit, plus some
> >> caml_curry* functions and camlCryptokit__* functions (compiled from
> >> OCaml). Is it true for you?
> > 
> > No, I only have camlCryptokit__sha1_init_3833 which I assume corresponds
> > to the function of src/cryptokit.ml:
> >  external sha1_init: unit -> string = "caml_sha1_init"
> 
> Then, I suspect stubs were forgotten during the build of cryptokit.cmxs.
> In the output of:
> 
>   ocamlobjinfo /path/to/cryptokit.cmxa
> 
> there should be the following lines:
> 
>   Extra C object files: -lcryptokit_stubs -lz
>   Extra C options:
> 
> Do you have the same lines? If so, maybe -linkall is missing in the call
> to ocamlopt -shared (the one that builds cryptokit.cmxs).

These lines are present in the .cmxa. But, sutdying the build commands,
the .cmxs is produced from cryptokit.cmx, not cryptokit.cmxa. Running
by hand 
# camlfind ocamlopt -shared -I src  src/cryptokit.cmxa -linkall -o \
  src/cryptokit.cmxs

includes the missing code:
# objdump -j .text -T src/cryptokit.cmxs | grep sha1_init
0000000000037e2b g    DF .text 000000000000001b  Base caml_sha1_init

I will report to the cryptokit authors. Thansk for your help !

Cheers,

Maxence