openssl/crypto/dso/README
Geoff Thorpe 51c8dc37dd This changes the behaviour of the DSO mechanism for determining an
appropriate filename translation on the host system. Apart from this point,
users should also note that there's a slight change in the API functions
too. The DSO now contains its own to-be-converted filename
("dso->filename"), and at the time the DSO loads the "dso->loaded_filename"
value is set to the translated form. As such, this also provides an impicit
way of determining if the DSO is currently loaded or not. Except, perhaps,
VMS .... :-)

The various DSO_METHODs have been updated for this mechanism except VMS
which is deliberately broken for now, Richard is going to look at how to
fit it in (the source comments in there explain "the issue").

Basically, the new callback scheme allows the filename conversion to
(a) be turned off altogether through the use of the
    DSO_FLAG_NO_NAME_TRANSLATION flag,
(b) be handled in the default way using the default DSO_METHOD's converter
(c) overriden per-DSO by setting the override callback
(d) a mix of (b) and (c) - eg. implement an override callback that;
    (i) checks if we're win32 "if(strstr(dso->meth->name, "win32"))..."
        and if so, convert "blah" into "blah32.dll" (the default is
	otherwise to make it "blah.dll").
    (ii) default to the normal behaviour - eg. we're not on win32, so
         finish with (return dso->meth->dso_name_converter(dso,NULL)).
(e) be retried a number of times by writing a new DSO_METHOD where the
    "dso_load()" handler will call the converter repeatedly. Then the
    custom converter could use state information in the DSO to suggest
    different conversions or paths each time it is invoked.
2000-10-26 17:38:59 +00:00

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NOTES
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I've checked out HPUX (well, version 11 at least) and shl_t is
a pointer type so it's safe to use in the way it has been in
dso_dl.c. On the other hand, HPUX11 support dlfcn too and
according to their man page, prefer developers to move to that.
I'll leave Richard's changes there as I guess dso_dl is needed
for HPUX10.20.
There is now a callback scheme in place where filename conversion can
(a) be turned off altogether through the use of the
DSO_FLAG_NO_NAME_TRANSLATION flag,
(b) be handled by default using the default DSO_METHOD's converter
(c) overriden per-DSO by setting the override callback
(d) a mix of (b) and (c) - eg. implement an override callback that;
(i) checks if we're win32 (if(strstr(dso->meth->name, "win32")....)
and if so, convert "blah" into "blah32.dll" (the default is
otherwise to make it "blah.dll").
(ii) default to the normal behaviour - we're not on win32, eg.
finish with (return dso->meth->dso_name_converter(dso,NULL)).