jmk <jmk_at_foofus.net> writes:
> On Tue, 2010-08-31 at 22:54 +0200, Simon Josefsson wrote:
>> It may be simpler to call libssh2_init globally before firing up any
>> threads. Then you only need to supply mutexes to the crypto library.
>
> Not feasible given the current design of my application -- all SSH code
> is contained within a module, which can be loaded by one or more
> threads.
Ouch. How does your application handle this for other libraries? There
are many libraries out there that need global initialization. So it may
make sense to consider making your application call a module-init
function before proceeding. Of course, this is speaking just generally,
and there may be reasons why this isn't an option for you.
> The core application doesn't have any SSH specific code in it.
> Fortunately, calling libssh2_init() multiple times doesn't *appear* to
> be causing me any issues.
The code looks like this:
libssh2_init(int flags)
{
if (_libssh2_initialized == 0 && !(flags & LIBSSH2_INIT_NO_CRYPTO)) {
libssh2_crypto_init();
}
_libssh2_initialized++;
_libssh2_init_flags |= flags;
return 0;
}
So there IS a race condition if two threads call the function at the
same time and there is a thread switch between the '==' comparison and
the '++' operation. But typically this won't happen.
Just make sure you call libssh2_exit as many times you call
libssh2_init, if you care at all about resource de-allocation.
/Simon
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Received on 2010-09-01