NAME
    AnyEvent::GDB - asynchronous GDB machine interface interface

SYNOPSIS
       use AnyEvent::GDB;

DESCRIPTION
    This module is an AnyEvent user, you need to make sure that you use and
    run a supported event loop.

    It implements the GDB MI protocol, which can be used to talk to GDB
    without having to parse the ever changing command syntax aimed at
    humans.

    It properly quotes your commands and parses the data structures returned
    by GDB.

    At the moment, it's in an early stage of development, so expect changes,
    and, over time, further features (such as breakpoint-specific callbacks
    and so on).

EXAMPLE PROGRAM
    To get you started, here is an example program that runs /bin/ls,
    displaying the stopped information when hitting a breakpoint on "_exit":

       use Data::Dump;
       use AnyEvent::GDB;

       our $gdb = new AnyEvent::GDB
          trace => 1,
          on_exec_stopped => sub {
             ddx $_[0];
          },
       ;

       my $done

       ddx $gdb->cmd_sync (file_exec_and_symbols => "/bin/ls");
       ddx $gdb->cmd_sync (break_insert => "_exit");
       ddx $gdb->cmd_sync ("exec_run");

       AE::cv->recv;

  PROTOCOL QUIRKS
   Minus vs. underscores
    The MI protocol uses "-" to separate name components, while in Perl, you
    use "_" for this purpose.

    This module usually accepts either form as input, and always converts
    names with "-" to names with "_", so the "library-loaded" notify might
    become "notify_library_loaded", and the "host-name" result in that event
    is stored in the "host_name" hash element in Perl.

   Output redirection
    Unfortunately, GDB has no (portable) provision to separate GDB
    input/output from program input/output. Obviously, without a distinction
    between program I/O and GDB I/O it becomes impossible to safely control
    GDB.

    There are two ways for you around it: redirect stdin/stdout yourself, or
    set a tty (eg. with the "inferior_set_tty" command).

    Unfortunately, the MI interface does not seem to support any kind of I/O
    redirection, so this module helps you a bit, by setting the
    "exec-wrapper" variable with a console "set" commmand. That is, this
    module does soeQmthing like the following for you, providing proper file
    descriptors for your actual stdin and stdout:

       set exec-wrapper <&5 >&6

    The actual I/O redirection operators are also stored in "$gdb->{stdio}",
    so you can even do it yourself, e.g. when providing your own wrapper:

       $self->cmd_raw ("set exec-wrapper $self->{stdio}", sub { });

    (You need to use a raw command, as the "correct" "gdb_set" MI command
    silently ignores any "exec-wrapper" setting).

  METHODS
    $gdb = new AnyEvent::GDB key => value...
        Create a new GDB object using the given named parameters.

        For initial experiments, it is highly recommended to run with
        tracing or at least "verbose" enabled. And don't forget to provide
        an "on_eof" callback.

           my $gdb = new AnyEvent::GDB
              on_eof => sub {
                 print "We are done.\n";
              },
              trace => 1; # or verbose => 1, for less output

        exec => $path (default: "gdb")
            The path of the GDB executable.

        args => [$string...] (default: ["-n"])
            An optional array of parameters to pass to GDB. This should not
            be used to load a program executable, use the
            "file_exec_and_symbols", "target_attach" or similar MI commands
            instead.

        trace => $boolean (default: 0)
            If true, then all commands sent to GDB are printed to STDOUT
            prefixed with "> ", and all replies received from GDB are
            printed to STDOUT prefixed with "< ".

        verbose => $boolean (default: true if trace is enabled, false
        otherwise)
            If true, then log output and possibly other information is
            printed to STDOUT.

        on_xxxx => $callback->(...)
            This specifies a callback for a specific event - see the EVENTS
            section later in this document.

    $gdb->cmd_raw ($command, $cb->($class, $results, $console))
        Execute a raw command: $command is sent unchanged to GDB. See "cmd_"
        for a description of the callback arguments.

        Example: execute a CLI command and print its output.

           $gdb->cmd_raw ("info sh", sub {
              print "$_[3]\n";
           });

    $gdb->cmd ($command => [$option...], $parameter..., $cb->($class,
    $results, $console))
        Execute a MI command and invoke the callback with the results.

        $command is a MI command name. The leading minus sign can be
        omitted, and instead of minus signs, you can use underscores, i.e.
        all the following command names are equivalent:

           "-break-insert"   # as documented in the GDB manual
           -break_insert     # using underscores and _ to avoid having to quote
           break_insert      # ditto, when e.g. used to the left of a =>
           "break-insert"    # no leading minus

        The second argument is an optional array reference with options
        (i.e. it can simply be missing). Each $option is either an option
        name (similar rules as with command names, i.e. no initial "--") or
        an array reference with the first element being the option name, and
        the remaining elements being parameters: [$option, $parameter...].

        The remaining arguments, excluding the last one, are simply the
        parameters passed to GDB.

        All options and parameters will be properly quoted.

        When the command is done, the callback $cb will be invoked with
        $class being one of "done", "connected", "error" or "exit" (note:
        not "running"), $results being a has reference with all the
        "variable=value" pairs from the result list.

        $console is an array reference with all the GDB console messages
        written while command executes (for MI commands, this should always
        be "undef" and can be ignored).

        Example: #todo#

    ($results, $console) = $gdb->cmd_sync ($command => [$option...],
    $parameter...]) =item $results = $gdb->cmd_sync ($command =>
    [$option...], $parameter...])
        Like "cmd", but blocks execution until the command has been
        executed, and returns the results if sucessful. Croaks when GDB
        returns with an error.

        This is purely a convenience method for small scripts: since it
        blocks execution using a condvar, it is not suitable to be used
        inside callbacks or modules.

        That is, unless Coro is used - with Coro, you can run multiple
        "cmd_sync" methods concurrently form multiple threads, with no
        issues.

  EVENTS
    AnyEvent::GDB is asynchronous in nature, as the goal of the MI interface
    is to be fully asynchronous. Due to this, a user of this interface must
    be prepared to handle various events.

    When an event is produced, the GDB object will look for the following
    four handlers and, if found, will call each one in order with the GDB
    object and event name (without "on_") as the first two arguments,
    followed by any event-specific arguments:

    on_event method on the GDB object
        Useful when subclassing.

    on_event constructor parameter/object member
        The callback specified as "on_event" parameter to the constructor.

    on_EVENTNAME method on the GDB object
        Again, mainly useful when subclassing.

    on_EVENTNAME constructor parameter/object member
        Any callback specified as "on_EVENTNAME" parameter to the
        constructor.

    You can change callbacks dynamically by simply replacing the
    corresponding "on_XXX" member in the $gdb object:

       $gdb->{on_event} = sub {
          # new event handler
       };

    Here's the list of events with a description of their arguments.

    on_eof => $cb->($gdb, "eof")
        Called whenever GDB closes the connection. After this event, the
        object is partially destroyed and must not be accessed again.

    on_target => $cb->($gdb, "target", $string)
        Output received from the target. Normally, this is sent directly to
        STDOUT by GDB, but remote targets use this hook.

    on_log => $cb->($gdb, "log", $string)
        Log output from GDB. Best printed to STDOUT in interactive sessions.

    on_TYPE => $cb->($gdb, "TYPE", $class, $results)
        Called for GDB "exec", "status" and "notify" event (TYPE is one of
        these three strings). $class is the class of the event, with "-"
        replaced by "_" everywhere.

        For each of these, the GDB object will create *two* events: one for
        TYPE, and one for TYPE_CLASS. Usuaully you should provide the more
        specific event (TYPE_CLASS).

    on_TYPE_CLASS => $cb->($gdb, "TYPE_CLASS", $results)
        Called for GDB "exec", "status" and "notify" event: TYPE is one of
        these three strings, the class of the event (with "-" replaced b
        "_"s) is appended to it to form the TYPE_CLASS (e.g. "exec_stopped"
        or "notify_library_loaded").

  STATUS STORAGE
    The default implementations of the event method store the thread,
    thread_group, recording, library and running status insid ethe $gdb
    object.

    You can access these at any time. Specifically, the following
    information is available:

    "$gdb->{thread_group}{*id*}"
        The "thread_group" member stores a hash for each existing thread
        group. The hash always contains the "id" member, but might also
        contain other members.

    "$gdb->{thread_group}{*id*}{pid}"
        The "pid" member only exists while the thread group is running a
        program, and contaisn the PID of the program.

    "$gdb->{thread_group}{*id*}{exit_code}"
        The "exit_code" member only exists after a program has finished
        executing, and before it is started again, and contains the exit
        code of the program.

    "$gdb->{thread_group}{*id*}{recording}"
        The "recording" member only exists if recording has been previously
        started, and is 1 if recoridng is currently active, and 0 if it has
        been stopped again.

    "$gdb->{thread}{*id*}"
        The "thread" member stores a hash for each existing thread. The hash
        always contains the "id" member with the thread id, and the
        "group_id" member with the corresponding thread group id.

    "$gdb->{thread}{*id*}{running}"
        The "running" member is 1 while the thread is, well, running, and is
        missing otherwise.

    "$gdb->{thread}{*id*}{stopped}"
        The "stopped" member contains the result list from the
        "on_exec_stopped" notification that caused the thread to stop, and
        only exists when the thread is topped.

    "$gdb->{library}{*id*}"
        The "library" member contains all results from the
        "on_library_loaded" event (such as "id", "target_name", "host_name"
        and potentially a "thread_group".

SEE ALSO
    AnyEvent,
    <http://sourceware.org/gdb/current/onlinedocs/gdb/GDB_002fMI.html#GDB_00
    2fMI>.

AUTHOR
       Marc Lehmann <schmorp@schmorp.de>
       http://home.schmorp.de/

