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NAME |
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AnyEvent::GDB - asynchronous GDB machine interface interface |
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|
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SYNOPSIS |
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use AnyEvent::GDB; |
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|
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DESCRIPTION |
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This module is an AnyEvent user, you need to make sure that you use and |
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run a supported event loop. |
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|
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It implements the GDB MI protocol, which can be used to talk to GDB |
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without having to parse the ever changing command syntax aimed at |
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humans. |
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|
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It properly quotes your commands and parses the data structures returned |
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by GDB. |
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|
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At the moment, it's in an early stage of development, so expect changes, |
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and, over time, further features (such as breakpoint-specific callbacks |
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and so on). |
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|
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EXAMPLE PROGRAM |
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To get you started, here is an example program that runs /bin/ls, |
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displaying the stopped information when hitting a breakpoint on "_exit": |
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|
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use Data::Dump; |
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use AnyEvent::GDB; |
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|
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our $gdb = new AnyEvent::GDB |
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trace => 1, |
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on_exec_stopped => sub { |
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ddx $_[0]; |
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}, |
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; |
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|
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my $done |
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|
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ddx $gdb->cmd_sync (file_exec_and_symbols => "/bin/ls"); |
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ddx $gdb->cmd_sync (break_insert => "_exit"); |
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ddx $gdb->cmd_sync ("exec_run"); |
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|
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AE::cv->recv; |
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|
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PROTOCOL QUIRKS |
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Minus vs. underscores |
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The MI protocol uses "-" to separate name components, while in Perl, you |
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use "_" for this purpose. |
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|
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This module usually accepts either form as input, and always converts |
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names with "-" to names with "_", so the "library-loaded" notify might |
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become "notify_library_loaded", and the "host-name" result in that event |
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is stored in the "host_name" hash element in Perl. |
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|
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Output redirection |
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Unfortunately, GDB has no (portable) provision to separate GDB |
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input/output from program input/output. Obviously, without a distinction |
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between program I/O and GDB I/O it becomes impossible to safely control |
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GDB. |
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|
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There are two ways for you around it: redirect stdin/stdout yourself, or |
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set a tty (eg. with the "inferior_set_tty" command). |
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|
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Unfortunately, the MI interface does not seem to support any kind of I/O |
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redirection, so this module helps you a bit, by setting the |
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"exec-wrapper" variable with a console "set" commmand. That is, this |
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module does soeQmthing like the following for you, providing proper file |
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descriptors for your actual stdin and stdout: |
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|
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set exec-wrapper <&5 >&6 |
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|
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The actual I/O redirection operators are also stored in "$gdb->{stdio}", |
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so you can even do it yourself, e.g. when providing your own wrapper: |
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|
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$self->cmd_raw ("set exec-wrapper $self->{stdio}", sub { }); |
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|
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(You need to use a raw command, as the "correct" "gdb_set" MI command |
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silently ignores any "exec-wrapper" setting). |
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|
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METHODS |
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$gdb = new AnyEvent::GDB key => value... |
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Create a new GDB object using the given named parameters. |
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|
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For initial experiments, it is highly recommended to run with |
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tracing or at least "verbose" enabled. And don't forget to provide |
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an "on_eof" callback. |
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|
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my $gdb = new AnyEvent::GDB |
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on_eof => sub { |
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print "We are done.\n"; |
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}, |
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trace => 1; # or verbose => 1, for less output |
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|
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exec => $path (default: "gdb") |
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The path of the GDB executable. |
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|
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args => [$string...] (default: ["-n"]) |
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An optional array of parameters to pass to GDB. This should not |
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be used to load a program executable, use the |
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"file_exec_and_symbols", "target_attach" or similar MI commands |
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instead. |
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|
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trace => $boolean (default: 0) |
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If true, then all commands sent to GDB are printed to STDOUT |
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prefixed with "> ", and all replies received from GDB are |
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printed to STDOUT prefixed with "< ". |
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|
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verbose => $boolean (default: true if trace is enabled, false |
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otherwise) |
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If true, then log output and possibly other information is |
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printed to STDOUT. |
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|
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on_xxxx => $callback->(...) |
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This specifies a callback for a specific event - see the EVENTS |
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section later in this document. |
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|
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$gdb->cmd_raw ($command, $cb->($class, $results, $console)) |
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Execute a raw command: $command is sent unchanged to GDB. See "cmd_" |
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for a description of the callback arguments. |
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|
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Example: execute a CLI command and print its output. |
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|
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$gdb->cmd_raw ("info sh", sub { |
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print "$_[3]\n"; |
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}); |
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|
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$gdb->cmd ($command => [$option...], $parameter..., $cb->($class, |
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$results, $console)) |
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Execute a MI command and invoke the callback with the results. |
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|
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$command is a MI command name. The leading minus sign can be |
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omitted, and instead of minus signs, you can use underscores, i.e. |
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all the following command names are equivalent: |
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|
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"-break-insert" # as documented in the GDB manual |
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-break_insert # using underscores and _ to avoid having to quote |
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break_insert # ditto, when e.g. used to the left of a => |
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"break-insert" # no leading minus |
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|
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The second argument is an optional array reference with options |
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(i.e. it can simply be missing). Each $option is either an option |
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name (similar rules as with command names, i.e. no initial "--") or |
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an array reference with the first element being the option name, and |
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the remaining elements being parameters: [$option, $parameter...]. |
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|
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The remaining arguments, excluding the last one, are simply the |
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parameters passed to GDB. |
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|
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All options and parameters will be properly quoted. |
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|
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When the command is done, the callback $cb will be invoked with |
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$class being one of "done", "connected", "error" or "exit" (note: |
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not "running"), $results being a has reference with all the |
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"variable=value" pairs from the result list. |
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|
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$console is an array reference with all the GDB console messages |
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written while command executes (for MI commands, this should always |
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be "undef" and can be ignored). |
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|
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Example: #todo# |
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|
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($results, $console) = $gdb->cmd_sync ($command => [$option...], |
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$parameter...]) =item $results = $gdb->cmd_sync ($command => |
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[$option...], $parameter...]) |
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Like "cmd", but blocks execution until the command has been |
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executed, and returns the results if sucessful. Croaks when GDB |
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returns with an error. |
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|
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This is purely a convenience method for small scripts: since it |
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blocks execution using a condvar, it is not suitable to be used |
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inside callbacks or modules. |
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|
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That is, unless Coro is used - with Coro, you can run multiple |
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"cmd_sync" methods concurrently form multiple threads, with no |
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issues. |
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|
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EVENTS |
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AnyEvent::GDB is asynchronous in nature, as the goal of the MI interface |
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is to be fully asynchronous. Due to this, a user of this interface must |
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be prepared to handle various events. |
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|
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When an event is produced, the GDB object will look for the following |
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four handlers and, if found, will call each one in order with the GDB |
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object and event name (without "on_") as the first two arguments, |
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followed by any event-specific arguments: |
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|
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on_event method on the GDB object |
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Useful when subclassing. |
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|
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on_event constructor parameter/object member |
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The callback specified as "on_event" parameter to the constructor. |
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|
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on_EVENTNAME method on the GDB object |
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Again, mainly useful when subclassing. |
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|
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on_EVENTNAME constructor parameter/object member |
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Any callback specified as "on_EVENTNAME" parameter to the |
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constructor. |
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|
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You can change callbacks dynamically by simply replacing the |
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corresponding "on_XXX" member in the $gdb object: |
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|
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$gdb->{on_event} = sub { |
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# new event handler |
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}; |
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|
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Here's the list of events with a description of their arguments. |
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|
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on_eof => $cb->($gdb, "eof") |
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Called whenever GDB closes the connection. After this event, the |
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object is partially destroyed and must not be accessed again. |
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|
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on_target => $cb->($gdb, "target", $string) |
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Output received from the target. Normally, this is sent directly to |
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STDOUT by GDB, but remote targets use this hook. |
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|
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on_log => $cb->($gdb, "log", $string) |
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Log output from GDB. Best printed to STDOUT in interactive sessions. |
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|
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on_TYPE => $cb->($gdb, "TYPE", $class, $results) |
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Called for GDB "exec", "status" and "notify" event (TYPE is one of |
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these three strings). $class is the class of the event, with "-" |
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replaced by "_" everywhere. |
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|
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For each of these, the GDB object will create *two* events: one for |
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TYPE, and one for TYPE_CLASS. Usuaully you should provide the more |
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specific event (TYPE_CLASS). |
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|
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on_TYPE_CLASS => $cb->($gdb, "TYPE_CLASS", $results) |
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Called for GDB "exec", "status" and "notify" event: TYPE is one of |
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these three strings, the class of the event (with "-" replaced b |
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"_"s) is appended to it to form the TYPE_CLASS (e.g. "exec_stopped" |
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or "notify_library_loaded"). |
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|
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STATUS STORAGE |
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The default implementations of the event method store the thread, |
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thread_group, recording, library and running status insid ethe $gdb |
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object. |
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|
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You can access these at any time. Specifically, the following |
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information is available: |
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|
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"$gdb->{thread_group}{*id*}" |
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The "thread_group" member stores a hash for each existing thread |
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group. The hash always contains the "id" member, but might also |
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contain other members. |
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|
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"$gdb->{thread_group}{*id*}{pid}" |
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The "pid" member only exists while the thread group is running a |
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program, and contaisn the PID of the program. |
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|
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"$gdb->{thread_group}{*id*}{exit_code}" |
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The "exit_code" member only exists after a program has finished |
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executing, and before it is started again, and contains the exit |
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code of the program. |
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|
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"$gdb->{thread_group}{*id*}{recording}" |
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The "recording" member only exists if recording has been previously |
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started, and is 1 if recoridng is currently active, and 0 if it has |
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been stopped again. |
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|
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"$gdb->{thread}{*id*}" |
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The "thread" member stores a hash for each existing thread. The hash |
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always contains the "id" member with the thread id, and the |
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"group_id" member with the corresponding thread group id. |
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|
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"$gdb->{thread}{*id*}{running}" |
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The "running" member is 1 while the thread is, well, running, and is |
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missing otherwise. |
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|
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"$gdb->{thread}{*id*}{stopped}" |
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The "stopped" member contains the result list from the |
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"on_exec_stopped" notification that caused the thread to stop, and |
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only exists when the thread is topped. |
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|
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"$gdb->{library}{*id*}" |
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The "library" member contains all results from the |
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"on_library_loaded" event (such as "id", "target_name", "host_name" |
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and potentially a "thread_group". |
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|
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SEE ALSO |
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AnyEvent, |
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<http://sourceware.org/gdb/current/onlinedocs/gdb/GDB_002fMI.html#GDB_00 |
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2fMI>. |
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|
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AUTHOR |
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Marc Lehmann <schmorp@schmorp.de> |
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http://home.schmorp.de/ |
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|
