libgdb 1.0 was an abortive project of years ago. The theory was
to provide an API to GDB's functionality.
libgdb 2.0 is an ongoing effort to update GDB so that is
better able to support graphical and other environments.
Since libgdb development is on-going, its architecture is still
evolving. The following components have so far been identified:
The model that ties these components together is described below.
libgdb Model
A client of libgdb interacts with the library in two ways.
libgdb of any internal state changes (break point changes, run
state, etc).
libgdb (using the `ui-out' builder) to
obtain various status values from GDB.
Since libgdb could have multiple clients (e.g. a GUI supporting
the existing GDB CLI), those clients must co-operate when
controlling libgdb. In particular, a client must ensure that
libgdb is idle (i.e. no other client is using libgdb)
before responding to a `gdb-event' by making a query.
At present GDB's CLI is very much entangled in with the core of
libgdb. Consequently, a client wishing to include the CLI in
their interface needs to carefully co-ordinate its own and the CLI's
requirements.
It is suggested that the client set libgdb up to be bi-modal
(alternate between CLI and client query modes). The notes below sketch
out the theory:
libgdb.
cli-out builder using its own
versions of the ui-file gdb_stderr, gdb_stdtarg and
gdb_stdout streams.
ui-out builder that is only
used while making direct queries to libgdb.
When the client receives input intended for the CLI, it simply passes it
along. Since the cli-out builder is installed by default, all
the CLI output in response to that command is routed (pronounced rooted)
through to the client controlled gdb_stdout et. al. streams.
At the same time, the client is kept abreast of internal changes by
virtue of being a libgdb observer.
The only restriction on the client is that it must wait until
libgdb becomes idle before initiating any queries (using the
client's custom builder).
libgdb components
`gdb-events' provides the client with a very raw mechanism that can
be used to implement an observer. At present it only allows for one
observer and that observer must, internally, handle the need to delay
the processing of any event notifications until after libgdb has
finished the current command.
`ui-out' provides the infrastructure necessary for a client to
create a builder. That builder is then passed down to libgdb
when doing any queries.
`event-loop', currently non-re-entrant, provides a simple event loop. A client would need to either plug its self into this loop or, implement a new event-loop that GDB would use.
The event-loop will eventually be made re-entrant. This is so that GDB can better handle the problem of some commands blocking instead of returning.
`libgdb' is the most obvious component of this system. It provides
the query interface. Each function is parameterized by a ui-out
builder. The result of the query is constructed using that builder
before the query function returns.
Go to the first, previous, next, last section, table of contents.