[Bug mi/20034] "set editing on" with MI as top-level interpreter -> gdb aborts

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=20034

--- Comment #2 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Pedro Alves <palves@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=3c216924d6ae534ea6c2f6bdcc4b42238af52ab1

commit 3c216924d6ae534ea6c2f6bdcc4b42238af52ab1
Author: Pedro Alves <palves@redhat.com>
Date:   Tue Jun 21 01:11:48 2016 +0100

    Make command line editing (use of readline) be per UI

    Due to the way that readline's API works (based on globals), we can
    only have one instance of readline in a process.  So the goal of this
    patch is to only allow editing in the main UI, and make sure that only
    one UI calls into readline.  Some MI paths touch readline variables
    currently, which is bad as that is changing variables that matter for
    the main console UI.  This patch fixes those.

    This actually fixes a nasty bug -- starting gdb in MI mode ("gdb
    -i=mi"), and then doing "set editing on" crashes GDB, because MI is
    not prepared to use readline:

     set editing on
     &"set editing on\n"
     =cmd-param-changed,param="editing",value="on"
     ^done
     (gdb)
     p 1
     readline: readline_callback_read_char() called with no handler!
     Aborted (core dumped)

    The fix for that was to add an interp_proc method to query the
    interpreter whether it actually supports editing.  New test included.

    gdb/ChangeLog:
    2016-06-21  Pedro Alves  <palves@redhat.com>

        PR mi/20034
        * cli/cli-interp.c: Include cli-interp.h and event-top.h.
        (cli_interpreter_resume): Pass 1 to gdb_setup_readline.  Set the
        UI's input_handler here.
        (cli_interpreter_supports_command_editing): New function.
        (cli_interp_procs): Install it.
        * cli/cli-interp.h: New file.
        * event-top.c (async_command_editing_p): Rename to ...
        (set_editing_cmd_var): ... this.
        (change_line_handler): Add parameter 'editing', and use it.  Bail
        early if the interpreter doesn't support editing.  Don't touch
        readline state if editing is off.
        (gdb_rl_callback_handler_remove, gdb_rl_callback_handler_install)
        (gdb_rl_callback_handler_reinstall): Assert the current UI is the
        main UI.
        (display_gdb_prompt): Don't call gdb_rl_callback_handler_remove if
        not using readline.  Check whether the current UI is using command
        editing instead of checking the async_command_editing_p global.
        (set_async_editing_command): Delete.
        (gdb_setup_readline): Add 'editing' parameter.  Only allow editing
        on the main UI.  Don't touch readline state if editing is off.
        (gdb_disable_readline): Don't touch readline state if editing is
        off.
        * event-top.h (gdb_setup_readline): Add 'int' parameter.
        (set_async_editing_command): Delete declaration.
        (change_line_handler, command_line_handler): Declare.
        (async_command_editing_p): Rename to ...
        (set_editing_cmd_var): ... this.
        * infrun.c (reinstall_readline_callback_handler_cleanup): Check
        whether the current UI has editing enabled rather than checking
        the async_command_editing_p global.
        * interps.c (interp_supports_command_editing): New function.
        * interps.h (interp_supports_command_editing_ftype): New typedef.
        (struct interp_procs) <supports_command_editing_proc>: New field.
        (interp_supports_command_editing): Declare.
        * mi/mi-interp.c (mi_interpreter_resume): Pass 0 to
        gdb_setup_readline.  Don't clear the async_command_editing_p
        global.  Update comments.
        * top.c (gdb_readline_wrapper_line, gdb_readline_wrapper): Check
        whether the current UI has editing enabled rather than checking
        the async_command_editing_p global.  Don't touch readline state if
        editing is off.
        (undo_terminal_modifications_before_exit): Switch to the main UI.
        Unconditionally call gdb_disable_readline.
        (set_editing): New function.
        (show_async_command_editing_p): Rename to ...
        (show_editing): ... this.  Show the state of the current UI.
        (_initialize_top): Adjust.
        * top.h (struct ui) <command_editing>: New field.
        * tui/tui-interp.c: Include cli/cli-interp.h.
        (tui_resume): Pass 1 to gdb_setup_readline.  Set the UI's
        input_handler.
        (tui_interp_procs): Install
        cli_interpreter_supports_command_editing.
        * tui/tui-io.c (tui_getc): Check whether the current UI has
        editing enabled rather than checking the async_command_editing_p
        global.

    gdb/testsuite/ChangeLog:
    2016-06-21  Pedro Alves  <palves@redhat.com>

        PR mi/20034
        * gdb.mi/mi-editing.exp: New file.

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