Currently, the functions return a pointer to the
destination buffer on success or NULL on failure.
Not only does this kind of error handling look quite
alien in the context of libvirt, where most functions
return zero on success and a negative int on failure,
but it's also somewhat pointless because unless there's
been a failure the returned pointer will be the same
one passed in by the user, thus offering no additional
value.
Change the functions so that they return an int
instead.
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
This convenience macro was created for the simple cases
where the length of the source string and the size of the
destination buffer can be figued out with strlen() and
sizeof() respectively, so we should use it wherever
possible instead of open-coding parts of it.
Signed-off-by: Andrea Bolognani <abologna@redhat.com>
https://bugzilla.redhat.com/show_bug.cgi?id=1529059
Commit id 0fe4aa14 added the thread specific error message
reporting (or save) to virFDStreamEvent; however, as processing
goes via virStream{Send|SendHole|Recv} via calls from
daemonStreamHandle{WriteData|Hole|Read} the last error
gets reset in the main libvirt API's thus, whatever error
may have been set as last error will be cleared prior to
the error paths using it resulting in the generic error
on the client side.
For each of the paths that check threadQuit or threadErr,
check if threadErr was set and set it agian if there isn't
a last error (e.g. some other failure) set so that the
message can be provided back to the client.
Signed-off-by: John Ferlan <jferlan@redhat.com>
ACKed-by: Michal Privoznik <mprivozn@redhat.com>
So far we are repeating the following lines over and over:
if (!(virSomeObjectClass = virClassNew(virClassForObject(),
"virSomeObject",
sizeof(virSomeObject),
virSomeObjectDispose)))
return -1;
While this works, it is impossible to do some checking. Firstly,
the class name (the 2nd argument) doesn't match the name in the
code in all cases (the 3rd argument). Secondly, the current style
is needlessly verbose. This commit turns example into following:
if (!(VIR_CLASS_NEW(virSomeObject,
virClassForObject)))
return -1;
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Seeing a log message saying 'flags=93' is ambiguous & confusing unless
you happen to know that libvirt always prints flags as hex. Change our
debug messages so that they always add a '0x' prefix when printing flags,
and '0' prefix when printing mode. A few other misc places gain a '0x'
prefix in error messages too.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Problem with our error reporting is that the error object is a
thread local variable. That means if there's an error reported
within the I/O thread it gets logged and everything, but later
when the event loop aborts the stream it doesn't see the original
error. So we are left with some generic error. We can do better
if we copy the error message between the threads.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
When the I/O thread quits (e.g. due to an I/O error, lseek()
error, whatever), any subsequent virFDStream API should return
error too. Moreover, when invoking stream event callback, we must
set the VIR_STREAM_EVENT_ERROR flag so that the callback knows
something bad happened.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
There's a problem with current streams after I switched them from
iohelper to thread implementation. Previously, iohelper made sure
not to exceed specified @length resulting in the pipe EOF
appearing at the exact right moment (the pipe was used to tunnel
the data from the iohelper to the daemon). Anyway, when switching
to thread I had to write the I/O code from scratch. Whilst doing
that I took an inspiration from the iohelper code, but since the
usage of pipe switched to slightly different meaning, there was
no 1:1 relationship between the codes.
Moreover, after introducing VIR_FDSTREAM_MSG_TYPE_HOLE, the
condition that should made sure we won't exceed @length was
completely wrong.
The fix is to:
a) account for holes for @length
b) cap not just data sections but holes too (if @length would be
exceeded)
For this purpose, the condition needs to be brought closer to the
code that handles holes and data sections.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Currently, we don't assign any meaning to that. Our current view
on virStream is that it's merely a pipe. And pipes don't support
seeking.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Basically, what is needed here is to introduce new message type
for the messages passed between the event loop callbacks and the
worker thread that does all the I/O. The idea is that instead of
a queue of read buffers we will have a queue where "hole of size
X" messages appear. That way the event loop callbacks can just
check the head of the queue and see if the worker thread is in
data or a hole section and how long the section is.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
One big downside of using the pipe to transfer the data is that
we can really transfer just bare data. No metadata can be carried
through unless some formatted messages are introduced. That would
be quite painful to achieve so let's use a message queue. It's
fairly easy to exchange info between threads now that iohelper is
no longer used.
The reason why we cannot use the FD for plain files directly is
that despite us setting noblock flag on the FD, any
read()/write() blocks regardless (which is a show stopper since
those parts of the code are run from the event loop) and poll()
reports such FD as always readable/writable - even though the
subsequent operation might block.
The pipe is still not gone though. It is used to signal the event
loop that an event occurred (e.g. data is available for reading
in the queue, or vice versa).
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Currently we use iohelper for virFDStream implementation. This is
because UNIX I/O can lie sometimes: even though a FD for a
file/block device is set as unblocking, actual read()/write() can
block. To avoid this, a pipe is created and one end is kept for
read/write while the other is handed over to iohelper to
write/read the data for us. Thus it's iohelper which gets blocked
and not our event loop.
This approach has two problems:
1) we are spawning a new process.
2) any exchange of information between daemon and iohelper can be
done only through the pipe.
Therefore, iohelper is replaced with an implementation in thread
which is created just for the stream lifetime. The data are still
transferred through pipe (for now), but both problems described
above are solved.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
While this is no functional change, it makes the code look a bit
nicer. Moreover, it prepares ground for future work.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
There is really no reason why we should have to have 'struct'
everywhere.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: John Ferlan <jferlan@redhat.com>
There is no reason for it not to be in the utils, all global symbols
under that file already have prefix vir* and there is no reason for it
to be part of DRIVER_SOURCES because that is just a leftover from
older days (pre-driver modules era, I believe).
Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
