Including C headers inside of `extern "C"` breaks use from C++. Hoist
the includes of standard C headers above the block so we don't try
to mangle the stdlib.
I initially tried to scope this with a targeted change but it's too
hard to do correctly that way. This way, we avoid whack-a-mole.
Firefox is working around this in their e21461b7b8b39cc31ba53c47d4f6f310c673ff2f
commit.
Bug: https://bugzilla.mozilla.org/1953080
Extend version 3 protocol with message footers, which are for passing
around global state data that is not addressed to a specific object.
The extension is backward compatible with previous v3 clients, and won't
e.g. result to error spam in logs.
The footer is a single SPA POD, appended after the main message POD.
Because both the protocol message and the message POD record their
length, it's possible to append trailing data. Earlier clients will
ignore any data trailing the message POD.
The footer POD contains a sequence [Id opcode, Struct {...}]*,
so there is room to extend with new opcodes later as necessary.
There are separate marshal/demarshal routines for messages aimed at
resources and proxies.
This also brings the advantage that all tools, examples, modules, components
can also be compiled standalone out-of-tree using libpipewire from the system
The message structures returned by pw_protocol_native_connection_get_next
point to data that is contained in the buffer of the connection.
The data was invalidated when pw_protocol_native_connection_get_next was
called the next time, which made the connection loop non-reentrant, in
cases where it was re-entered from demarshal callbacks.
Fix this by allocating new buffers when reentering and stashing the old
buffers onto a stack. The returned message structure is also stored on
the stack to make lifetimes to match.
The proxy API is the one that we would like to expose for applications
and the other API is used internally when implementing modules or
factories.
The current pw_core object is really a context for all objects so
name it that way. It also makes it possible to rename pw_core_proxy
to pw_proxy later.
Make the connection as soon as we create the client. We create it
without file descriptor and then set it when we connect. This
makes it possible to use the connection to queue messages before
we connect.
For flatpaks we need to be able to support older v0 protocol clients.
To handle this we have:
- the connection detects an old client when it receives the first
message. It can do this by checking the sequence number, on old
versions it contains the message size and is never 0, on new
clients the sequence number is 0.
- We add a new signal at the start of the connection with the detected
version number. This installs the right version of the core proxy.
We also move the binding of the client until the hello message is
received. This way we can have a new client connect (portal),
hand over the connection to an old client, which then removes the
client binding again in the hello request with a v0 version.
There are some changes to the passing of fds in v0 vs v3 which need
to investigated some more.
- bump version of our interfaces to 3. This makes it possible to
have v0 and v3 protocol marshal functions.
- Add version number in the proxy. This is mostly automatically done
internally based on the version numbers the library is compiled
with. Where the version number was in the API before, it is now
actually used to look up the right protocol marshal functions. For
Proxies there is usually just 1 version, the current one. It is the
server that will support different versions.
- Add v0 compat marshal functions to convert from and to v0 format.
This has some complications. v0 has a type map it keeps in sync
with the server. For this we have a static type map with mappings
to our own v3 types. Pods are mostly the same except for objects
that used to have arbitrary pods in v0 vs spa_pod_prop in v3. Also
convert between v0 spa_pod_prop and v3 spa_pod_choice.
Formats and commands are also slightly different so handle those
mappings as well.
We only have marshal functions for the server side (resource)
v0 functions.
- Add v0 compatible client-node again. It's a bit tricky to map, v0
client-node basically lets the server to the mixing and teeing
and just does the processing of the internal node.
Pass a message around to make things more extensible later.
Keep fds per message if we ever want to write individual
messages.
Pass number of fds in the message header. We might need this to
close the fds when the proxy is gone.
Don't use special callback in node to receive the results. Instead,
use a generic result callback to receive the result. This makes things
a bit more symetric and generic again because then you can choose how
to match the result to the request and you have a generic way to handle
both the sync and async case. We can then also remove the wait method.
This also makes the remote interface and spa interface to objects very
similar.
Make a helper object to receive and dispatch results. Use this in the
helper for enum_params.
Make device use the same result callbacks.
Remove the done and error callbacks. The error callback is in an
error message. The done callback is replace with spa_pending.
Make enum_params take a callback and data for the results. This allows
us to push the results one after another to the app and avoids ownership
issues of the passed data. We can then extend this to handle the async
case by doing a _wait call with a spa_pending+callback+data that will
be called when the _enum_params returns and async result.
Add a sync method.
All methods can now return SPA_RESULT_IS_ASYNC return values and you
can use spa_node_wait() to register a callback when they complete
with optional extra parameters. This makes it easier to sync and
handle the reply.
Make helper methods to simulate the sync enum_params behaviour for
sync nodes.
Let the transport generate the sequence number for pw_resource_sync()
and pw_proxy_sync(). That way we don't need to keep track of numbers
ourselves and we can match the reply to the request easily.
Add return values to events and method callbacks. This makes it
possible to pass any error or async return value.
Add sync/done/error in both directions so that both proxy and resource
and perform/reply sync and produce errors.
Return a SPA_ASYNC from remote method calls (and events), keep the
sequence number in the connection.
With the core sync/done we can remove the client-node done method and
it's internal sequence number along with the seq number in method calls.
We can also use the method/event async return value to perform a sync
with as the unique sequence number for this method.
Add sync method and done/error event to proxy and resource.
Pass the minimum required version to the hook emission and only call
events when the handler is recent enough.
Add some macros to make event emission easier to read.
The listeners are generally useful in spa, move it there and rename
to hooks. Implement loop hooks with it.
Fix some cleanup issues in stream and remote
Remove signals.
Rename callbacks -> events, use listeners to listen for events.
Callbacks are still used in spa for things you can listen to only
once.
Add hooks that contain protocol specific interfaces that can be used
to extend the protocol. This makes it possible to add new interfaces
to the protocol and implement the protocol specific data transport.
Move these protocol specific extension to the extensions directory.
