Re: Error reporting should be improved

[Bob Friesenhahn]

On Tue, 29 Dec 2009, Peter Rosin wrote:
> I'm just saying that it is not going to be easy to deduce if an
> error is allowed to be overwritten.
>
> Have a look at libltdl/loaders/dlopen.c:vm_open(). It basically
> calls dlopen and sets the error to CANNOT_OPEN if dlopen fails.
> The ways I see to dig out the underlying failure is to either call
> dlerror and parse the string (Eeek!) or replicate the dlopen
> internals and arrive at the same cause as dlopen did (EEEK!).

If dlerror() is available it is supposed to be ignoring the supplied 
CANNOT_OPEN code and invoking dlerror() instead:

#if defined(HAVE_DLERROR)
#  define DLERROR(arg)  dlerror ()
#else
#  define DLERROR(arg)  LT__STRERROR (arg)
#endif

#define DL__SETERROR(errorcode) \
        LT__SETERRORSTR (DLERROR (errorcode))

Bob
--
Bob Friesenhahn
address@hidden, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/