On Fri, Jun 28, 2019 at 01:53:11PM -0500, Eric Blake wrote: > On 6/28/19 1:27 PM, Richard W.M. Jones wrote: > > Previously errors caused a RuntimeException to be raised. This commit > > defines a custom exception (nbd.Error) which has two parameters, the > > required error string, and the optional errno (which may be 0 if > > unavailable). > > > > For example: > > > > $ ./run nbdsh -c 'h.pread(0, 0)' > > Traceback (most recent call last): > > File "/usr/lib64/python3.7/runpy.py", line 193, in _run_module_as_main > > "__main__", mod_spec) > > File "/usr/lib64/python3.7/runpy.py", line 85, in _run_code > > exec(code, run_globals) > > File "/home/rjones/d/libnbd/python/nbd.py", line 1163, in <module> > > nbdsh.shell() > > File "/home/rjones/d/libnbd/python/nbdsh.py", line 62, in shell > > exec (c) > > File "<string>", line 1, in <module> > > File "/home/rjones/d/libnbd/python/nbd.py", line 483, in pread > > return libnbdmod.pread (self._o, count, offset, flags) > > nbd.Error: nbd_pread: invalid state: START: the handle must be connected > > and finished handshaking with the server: Transport endpoint is not > > connected (ENOTCONN) > > Cool - in the time I spent writing my reply to v2 1/1, your reaction to > my reply on 0/1 figured out the way to get what we want: > > > > @@ -3917,6 +3938,36 @@ Read the libnbd(3) man page to find out how to use > > the API. > > > > import libnbdmod > > > > +# Re-export Error exception as nbd.Error, adding some methods. > > +from libnbdmod import Error > > Implement all the cool stuff in pure Python on top of the bare-bones > minimum :) Lots less hassle than writing it in C code. I like it! > > > + > > +Error.__doc__ = ''' > > +Exception thrown when the underlying libnbd call fails. > > + > > +This exception has two properties to query the error. Use > > +the .string property to return a printable string containing > > +the error message. Use the .errno property to return a > > +Python errno (which may be None in some cases if the error > > +did not correspond to a system call failure). > > +''' > > + > > +Error.string = property (lambda self: self.args[0]) > > + > > +def _errno (self): > > + import errno > > + try: > > + return errno.errorcode[self.args[1]] > > + except KeyError: > > + return None > > +Error.errno = property (_errno) > > + > > +def _str (self): > > + if self.errno: > > + return (\"%%s (%%s)\" %% (self.string, self.errno)) > > + else: > > + return (\"%%s\" %% self.string) > > +Error.__str__ = _str > > Looks good to me now! Thanks for figuring this out while I was > struggling with reading lots of documentation on C bindings. > > ACK
I pushed it, but there may be a few issues still: - Still no error checking in raise_exception(). We're on an error path already here so it's hard to do anything useful, although perhaps we should not segfault. - The .errno attribute returns a (Python module) errno value, not a number, so the number is effectively lost, should that really be an issue. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-builder quickly builds VMs from scratch http://libguestfs.org/virt-builder.1.html _______________________________________________ Libguestfs mailing list [email protected] https://www.redhat.com/mailman/listinfo/libguestfs
