[PATCH] dynamic printf
Stan Shebs
stanshebs@earthlink.net
Wed Feb 29 09:14:00 GMT 2012
This patch implements a "dynamic printf", which is basically a
breakpoint with a printf;continue as its command list - but with
additional features that make it more interesting. First, there is an
option to send the result to the inferior's output stream rather than to
the GDB console; second, there is an option to do the printing in a
remote agent/stub; and third, the agent version can continue printf'ing
even after GDB detaches(!).
(For those who pay attention to the competitive landscape, this is an
Ericsson-requested GDBification of a Wind River feature.)
The syntax of the command is
dprintf <location> <format>,<arg>,<arg>...
where the location is as for breakpoints, while the format and args are
as for the printf command. So you could have something like
dprintf myfun "myfun args are %d,%d\n",arg1,arg2
A setshow variable dprintf-style controls whether the printing is done
by GDB, the inferior, or by a remote agent, and another variable
disconnected-dprintf controls persistence upon disconnection, similarly
to disconnected tracing.
The patch itself is somewhat of a hack-n-slash through the middle of
GDB, and there is much to critique. :-) Partly this is because I wanted
to push through to a genuinely useful example of target-side breakpoint
commands, rather than doing limited-functionality "commands" in the
abstract. It also points up our continuing need for being able to
define types of breakpoints by properties rather than adding enums... I
borrowed some of Luis' target-side conditional code, and got some
inspiration from Hui Zhu's previous try at a printf bytecode.
Anyway, without further ado, here's the patch itself. I've skipped the
testsuite for now, as I expect everybody will want nontrivial
modifications. :-)
Stan
2012-02-28 Stan Shebs <stan@codesourcery.com>
Add dynamic printf.
* breakpoint.h (enum bptype): New type bp_dprintf.
(struct bp_target_info): New field commands and persist.
(struct bp_location): New field cmd_bytecode.
(struct breakpoint): New field extra_string.
* breakpoint.c (dprintf_breakpoint_ops): New.
(disconnected_dprintf): New global.
(is_breakpoint): Add bp_dprintf.
(parse_format_string): New function.
(parse_cmd_to_aexpr): New function.
(build_target_command_list): New function.
(insert_bp_location): Call it.
(remove_breakpoints_pid): Skip dprintf breakpoints.
(bpstat_what): Add dprintf case.
(bptype_string): Ditto.
(print_one_breakpoint_location): Ditto.
(init_bp_location): Ditto.
(bkpt_print_mention): Ditto.
(dprintf_style_enums): New array.
(dprintf_style): New global.
(glob_extra_string): New global.
(init_breakpoint_sal): Handle extra string.
(addr_string_to_sals): Ditto.
(find_condition_and_thread): Add extra argument.
(create_breakpoint): Save away additional text at end of command.
(dprintf_command): New function.
(_initialize_breakpoint): Add new commands.
* common/ax.def (printf): New bytecode.
* ax-gdb.c (gen_printf): New function.
(agent_print_command): New function.
(_initialize_ax_gdb): Add maint agent-printf command.
* ax-gdb.h (gen_printf): Declare.
* ax-general.c (ax_print): Add printf disassembly.
* remote.c (remote_state) <cond_breakpoints>: New field.
(PACKET_BreakpointCommandss): New enum.
(remote_breakpoint_commands_feature): New function.
(remote_protocol_features): Add new BreakpointCommands entry.
(remote_can_run_breakpoint_commands): New function.
(remote_add_target_side_commands): New function.
(remote_insert_breakpoint): Call it.
(remote_insert_hw_breakpoint): Ditto.
(_initialize_remote): Add new packet configuration for
target-side breakpoint commands.
* target.h (struct target_ops): New field
to_can_run_breakpoint_commands.
(target_can_run_breakpoint_commands): New macro.
* target.c (update_current_target): Handle
to_can_run_breakpoint_commands.
[gdbserver]
* server.c (handle_query): Claim support for breakpoint commands.
(process_point_options): Add command case.
(process_serial_event): Leave running if there are printfs in
effect.
* mem-break.c (struct point_command_list): New struct.
(struct breakpoint): New field command_list.
(any_persistent_commands): New function.
(add_commands_to_breakpoint): New function.
(add_breakpoint_commands): New function.
(gdb_no_commands_at_breakpoint): New function.
(run_breakpoint_commands): New function.
* mem-break.h (any_persistent_commands): Declare.
(add_breakpoint_commands): Declare.
(gdb_no_commands_at_breakpoint): Declare.
(run_breakpoint_commands): Declare.
* linux-low.c (linux_wait_1): Test for and run breakpoint commands
locally.
* ax.c (gdb_eval_agent_expr): Add printf opcode.
[doc]
* gdb.texinfo (Dynamic Printf): New subsection.
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