Re: Distributed objects: can't send simple C struct by value
Re: Distributed objects: can't send simple C struct by value
- Subject: Re: Distributed objects: can't send simple C struct by value
- From: Wade Tregaskis <email@hidden>
- Date: Sun, 31 Oct 2004 01:21:13 +1000
Here is a dump of the struct in the sender just before sending:
BFFFE990: AAAAAAAA 54686973 20697320 6D792074 ....This is my t
BFFFE9A0: 65737420 73747269 6E672077 68696368 est string which
BFFFE9B0: 20676574 73207061 72746C79 20776970 gets partly wip
BFFFE9C0: 6564206F 75742E00 00000000 00000000 ed out..........
BFFFE9D0: 00000000 BBBBBBBB ........
Here it is in the receiver:
BFFFE650: AAAAAAAA 54686973 20697320 6D792074 ....This is my t
BFFFE660: 65737420 73747269 6E672077 A0A03CD4 est string w..<.
BFFFE670: 00528BB0 BFFFE6F0 A0A01234 909FA88C .R.........4....
BFFFE680: BFFFEB00 24022244 909FABF0 02800000 ....$."D........
BFFFE690: 00000020 00000018 ... ....
If I set up authenticationDataForComponents / authenticateComponents
delegates on both ends and look at the encoded data in the sender just
after encoding the corruption has already happened. I suspect that
this has something to do with the way structures are passed by value
by the compiler -- I believe that the first part of structs are passed
in registers, and the remainder on the stack. I'm guessing that the
encoder is not properly taking this into account.
I'm pretty sure gcc doesn't pass values in registers unless
specifically instructed to at compile time, so unless you're doing so
with your own code, I doubt it. Nonetheless, your suspicion does seem
plausible given the values that are being substituted... are these
values in any way reliable, or do they appear to be random?
For a definitive test of your theory, check the contents of the
registers at some stage before the data is actually sent down the wire,
and compare it to what you receive... if your theory is correct (and
you check the register contents close enough to where the data is
actually sent) you should see some clear correlation.
I'd be very surprised, nonetheless, if this were the issue you
postulate... it's hard to imagine no one else would have struck this at
any point, even if it is limited to DO. I would imagine the struct is
treated simply as a character array of length sizeof(_Msg), so if it
were in any way broken, nothing would work (since ultimately everything
has to be treated as a character array at one point or another).
I can't think of any alternatives possibilities, though. I'd be very
interested to hear of any progress you make, and of course the final
answer if you can find it.
Wade Tregaskis (AIM, Yahoo & Skype: wadetregaskis, ICQ: 40056898, MSN &
email: email@hidden, Jabber:
email@hidden
-- Sed quis custodiet ipsos custodes?
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