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path: root/src/libsystemd/sd-bus/test-bus-marshal.c
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2015-04-11bus: implement bus_path_{en,de}code_unique()David Herrmann
Whenever we provide a bus API that allows clients to create and manage server-side objects, we need to provide a unique name for these objects. There are two ways to provide them: 1) Let the server choose a name and return it as method reply. 2) Let the client pass its name of choice in the method arguments. The first method is the easiest one to implement. However, it suffers from a race condition: If a client creates an object asynchronously, it cannot destroy that object until it received the method reply. It cannot know the name of the new object, thus, it cannot destroy it. Furthermore, this method enforces a round-trip. If the client _depends_ on the method call to succeed (eg., it would close() the connection if it failed), the client usually has no reason to wait for the method reply. Instead, the client can immediately schedule further method calls on the newly created object (in case the API guarantees in-order method-call handling). The second method fixes both problems: The client passes an object name with the method-call. The server uses it to create the object. Therefore, the client can schedule object destruction even if the object-creation hasn't finished, yet (again, requiring in-order method-call handling). Furthermore, the client can schedule further method calls on the newly created object, before the constructor returned. There're two problems to solve, though: 1) Object names are usually defined via dbus object paths, which are usually globally namespaced. Therefore, multiple clients must be able to choose unique object names without interference. 2) If multiple libraries share the same bus connection, they must be able to choose unique object names without interference. The first problem is solved easily by prefixing a name with the unique-bus-name of a connection. The server side must enforce this and reject any other name. The second problem is solved by providing unique suffixes from within sd-bus. As long as sd-bus always returns a fresh new ID, if requested, multiple libraries will never interfere. This implementation re-uses bus->cookie as ID generator, which already provides unique IDs for each bus connection. This patch introduces two new helpers: bus_path_encode_unique(sd_bus *bus, const char *prefix, const char *sender_id, const char *external_id, char **ret_path); This creates a new object-path via the template '/prefix/sender_id/external_id'. That is, it appends two new labels to the given prefix. If 'sender_id' is NULL, it will use bus->unique_name, if 'external_id' is NULL, it will allocate a fresh, unique cookie from bus->cookie. bus_path_decode_unique(const char *path, const char *prefix, char **ret_sender, char **ret_external); This reverses what bus_path_encode_unique() did. It parses 'path' from the template '/prefix/sender/external' and returns both suffix-labels in 'ret_sender' and 'ret_external'. In case the template does not match, 0 is returned and both output arguments are set to NULL. Otherwise, 1 is returned and the output arguments contain the decoded labels. Note: Client-side allocated IDs are inspired by the Wayland protocol (which itself was inspired by X11). Wayland uses those IDs heavily to avoid round-trips. Clients can create server-side objects and send method calls without any round-trip and waiting for any object IDs to be returned. But unlike Wayland, DBus uses gobally namespaced object names. Therefore, we have to add the extra step by adding the unique-name of the bus connection.
2015-02-23remove unused includesThomas Hindoe Paaboel Andersen
This patch removes includes that are not used. The removals were found with include-what-you-use which checks if any of the symbols from a header is in use.
2015-01-23sd-bus: fix handling of double parameters in sd_bus_message_append()Lennart Poettering
We really need to use va_arg() with the right type here as uint64_t and double might have the same size, but are passed differently as arguments.
2014-11-14busctl: introduce busctl "get-property" command for reading and dumping ↵Lennart Poettering
object properties
2014-06-06sd-bus: don't allow creating message objects that are not attached to a busLennart Poettering
It seems unnecessary to support this, and we rather should avoid allowing this at all, so that people don't program against this sloppily and we end up remarshalling all the time...
2014-05-15Remove unnecessary casts in printfsZbigniew Jędrzejewski-Szmek
No functional change expected :)
2014-03-11bus: replace sd_bus_label_{escape,unescape}() by new ↵Lennart Poettering
sd_bus_path_{encode,decode}() The new calls work similarly, but enforce a that a common, fixed bus path prefix is used. This follows discussions with Simon McVittie on IRC that it should be a good idea to make sure that people don't use the escaping applied here too wildly as anything other than the last label of a bus path.
2014-03-06man: describe functions for appending to messagesZbigniew Jędrzejewski-Szmek
2014-02-20api: in constructor function calls, always put the returned object pointer ↵Lennart Poettering
first (or second) Previously the returned object of constructor functions where sometimes returned as last, sometimes as first and sometimes as second parameter. Let's clean this up a bit. Here are the new rules: 1. The object the new object is derived from is put first, if there is any 2. The object we are creating will be returned in the next arguments 3. This is followed by any additional arguments Rationale: For functions that operate on an object we always put that object first. Constructors should probably not be too different in this regard. Also, if the additional parameters might want to use varargs which suggests to put them last. Note that this new scheme only applies to constructor functions, not to all other functions. We do give a lot of freedom for those. Note that this commit only changes the order of the new functions we added, for old ones we accept the wrong order and leave it like that.
2014-01-21libsystemd: split up into subdirsTom Gundersen
We still only produce on .so, but let's keep the sources separate to make things a bit less messy.