/* Top level stuff for GDB, the GNU debugger.
- Copyright (C) 1999-2016 Free Software Foundation, Inc.
+ Copyright (C) 1999-2017 Free Software Foundation, Inc.
Written by Elena Zannoni <ezannoni@cygnus.com> of Cygnus Solutions.
/* readline defines this. */
#undef savestring
-static void rl_callback_read_char_wrapper (gdb_client_data client_data);
-static void command_line_handler (char *rl);
-static void change_line_handler (void);
static char *top_level_prompt (void);
/* Signal handlers. */
#endif
static void async_sigterm_handler (gdb_client_data arg);
-/* Readline offers an alternate interface, via callback
- functions. These are all included in the file callback.c in the
- readline distribution. This file provides (mainly) a function, which
- the event loop uses as callback (i.e. event handler) whenever an event
- is detected on the standard input file descriptor.
- readline_callback_read_char is called (by the GDB event loop) whenever
- there is a new character ready on the input stream. This function
- incrementally builds a buffer internal to readline where it
- accumulates the line read up to the point of invocation. In the
- special case in which the character read is newline, the function
- invokes a GDB supplied callback routine, which does the processing of
- a full command line. This latter routine is the asynchronous analog
- of the old command_line_input in gdb. Instead of invoking (and waiting
- for) readline to read the command line and pass it back to
- command_loop for processing, the new command_line_handler function has
- the command line already available as its parameter. INPUT_HANDLER is
- to be set to the function that readline will invoke when a complete
- line of input is ready. CALL_READLINE is to be set to the function
- that readline offers as callback to the event_loop. */
-
-void (*input_handler) (char *);
-void (*call_readline) (gdb_client_data);
+/* Instead of invoking (and waiting for) readline to read the command
+ line and pass it back for processing, we use readline's alternate
+ interface, via callback functions, so that the event loop can react
+ to other event sources while we wait for input. */
/* Important variables for the event loop. */
ezannoni: as of 1999-04-29 I expect that this
variable will not be used after gdb is changed to use the event
loop as default engine, and event-top.c is merged into top.c. */
-int async_command_editing_p;
+int set_editing_cmd_var;
/* This is used to display the notification of the completion of an
asynchronous execution command. */
int exec_done_display_p = 0;
-/* This is the file descriptor for the input stream that GDB uses to
- read commands from. */
-int input_fd;
-
/* Used by the stdin event handler to compensate for missed stdin events.
Setting this to a non-zero value inside an stdin callback makes the callback
run again. */
#endif
static struct async_signal_handler *async_sigterm_token;
-/* This hook is called by rl_callback_read_char_wrapper after each
+/* This hook is called by gdb_rl_callback_read_char_wrapper after each
character is processed. */
void (*after_char_processing_hook) (void);
\f
-/* Wrapper function for calling into the readline library. The event
- loop expects the callback function to have a paramter, while
- readline expects none. */
+/* Wrapper function for calling into the readline library. This takes
+ care of a couple things:
+
+ - The event loop expects the callback function to have a parameter,
+ while readline expects none.
+
+ - Propagation of GDB exceptions/errors thrown from INPUT_HANDLER
+ across readline requires special handling.
+
+ On the exceptions issue:
+
+ DWARF-based unwinding cannot cross code built without -fexceptions.
+ Any exception that tries to propagate through such code will fail
+ and the result is a call to std::terminate. While some ABIs, such
+ as x86-64, require all code to be built with exception tables,
+ others don't.
+
+ This is a problem when GDB calls some non-EH-aware C library code,
+ that calls into GDB again through a callback, and that GDB callback
+ code throws a C++ exception. Turns out this is exactly what
+ happens with GDB's readline callback.
+
+ In such cases, we must catch and save any C++ exception that might
+ be thrown from the GDB callback before returning to the
+ non-EH-aware code. When the non-EH-aware function itself returns
+ back to GDB, we then rethrow the original C++ exception.
+
+ In the readline case however, the right thing to do is to longjmp
+ out of the callback, rather than do a normal return -- there's no
+ way for the callback to return to readline an indication that an
+ error happened, so a normal return would have rl_callback_read_char
+ potentially continue processing further input, redisplay the
+ prompt, etc. Instead of raw setjmp/longjmp however, we use our
+ sjlj-based TRY/CATCH mechanism, which knows to handle multiple
+ levels of active setjmp/longjmp frames, needed in order to handle
+ the readline callback recursing, as happens with e.g., secondary
+ prompts / queries, through gdb_readline_wrapper. This must be
+ noexcept in order to avoid problems with mixing sjlj and
+ (sjlj-based) C++ exceptions. */
+
+static struct gdb_exception
+gdb_rl_callback_read_char_wrapper_noexcept () noexcept
+{
+ struct gdb_exception gdb_expt = exception_none;
+
+ /* C++ exceptions can't normally be thrown across readline (unless
+ it is built with -fexceptions, but it won't by default on many
+ ABIs). So we instead wrap the readline call with a sjlj-based
+ TRY/CATCH, and rethrow the GDB exception once back in GDB. */
+ TRY_SJLJ
+ {
+ rl_callback_read_char ();
+ if (after_char_processing_hook)
+ (*after_char_processing_hook) ();
+ }
+ CATCH_SJLJ (ex, RETURN_MASK_ALL)
+ {
+ gdb_expt = ex;
+ }
+ END_CATCH_SJLJ
+
+ return gdb_expt;
+}
+
static void
-rl_callback_read_char_wrapper (gdb_client_data client_data)
+gdb_rl_callback_read_char_wrapper (gdb_client_data client_data)
{
- rl_callback_read_char ();
- if (after_char_processing_hook)
- (*after_char_processing_hook) ();
+ struct gdb_exception gdb_expt
+ = gdb_rl_callback_read_char_wrapper_noexcept ();
+
+ /* Rethrow using the normal EH mechanism. */
+ if (gdb_expt.reason < 0)
+ throw_exception (gdb_expt);
}
-/* Initialize all the necessary variables, start the event loop,
- register readline, and stdin, start the loop. The DATA is the
- interpreter data cookie, ignored for now. */
+/* GDB's readline callback handler. Calls the current INPUT_HANDLER,
+ and propagates GDB exceptions/errors thrown from INPUT_HANDLER back
+ across readline. See gdb_rl_callback_read_char_wrapper. This must
+ be noexcept in order to avoid problems with mixing sjlj and
+ (sjlj-based) C++ exceptions. */
-void
-cli_command_loop (void *data)
+static void
+gdb_rl_callback_handler (char *rl) noexcept
{
- display_gdb_prompt (0);
+ struct gdb_exception gdb_rl_expt = exception_none;
+ struct ui *ui = current_ui;
- /* Now it's time to start the event loop. */
- start_event_loop ();
+ TRY
+ {
+ ui->input_handler (rl);
+ }
+ CATCH (ex, RETURN_MASK_ALL)
+ {
+ gdb_rl_expt = ex;
+ }
+ END_CATCH
+
+ /* If we caught a GDB exception, longjmp out of the readline
+ callback. There's no other way for the callback to signal to
+ readline that an error happened. A normal return would have
+ readline potentially continue processing further input, redisplay
+ the prompt, etc. (This is what GDB historically did when it was
+ a C program.) Note that since we're long jumping, local variable
+ dtors are NOT run automatically. */
+ if (gdb_rl_expt.reason < 0)
+ throw_exception_sjlj (gdb_rl_expt);
}
/* Change the function to be invoked every time there is a character
therefore bypassing readline, and letting gdb handle the input
itself, via gdb_readline_no_editing_callback. Also it is used in
the opposite case in which the user sets editing on again, by
- restoring readline handling of the input. */
-static void
-change_line_handler (void)
+ restoring readline handling of the input.
+
+ NOTE: this operates on input_fd, not instream. If we are reading
+ commands from a file, instream will point to the file. However, we
+ always read commands from a file with editing off. This means that
+ the 'set editing on/off' will have effect only on the interactive
+ session. */
+
+void
+change_line_handler (int editing)
{
- /* NOTE: this operates on input_fd, not instream. If we are reading
- commands from a file, instream will point to the file. However in
- async mode, we always read commands from a file with editing
- off. This means that the 'set editing on/off' will have effect
- only on the interactive session. */
+ struct ui *ui = current_ui;
- if (async_command_editing_p)
+ /* We can only have one instance of readline, so we only allow
+ editing on the main UI. */
+ if (ui != main_ui)
+ return;
+
+ /* Don't try enabling editing if the interpreter doesn't support it
+ (e.g., MI). */
+ if (!interp_supports_command_editing (top_level_interpreter ())
+ || !interp_supports_command_editing (command_interp ()))
+ return;
+
+ if (editing)
{
+ gdb_assert (ui == main_ui);
+
/* Turn on editing by using readline. */
- call_readline = rl_callback_read_char_wrapper;
- input_handler = command_line_handler;
+ ui->call_readline = gdb_rl_callback_read_char_wrapper;
}
else
{
/* Turn off editing by using gdb_readline_no_editing_callback. */
- gdb_rl_callback_handler_remove ();
- call_readline = gdb_readline_no_editing_callback;
-
- /* Set up the command handler as well, in case we are called as
- first thing from .gdbinit. */
- input_handler = command_line_handler;
+ if (ui->command_editing)
+ gdb_rl_callback_handler_remove ();
+ ui->call_readline = gdb_readline_no_editing_callback;
}
+ ui->command_editing = editing;
}
/* The functions below are wrappers for rl_callback_handler_remove and
void
gdb_rl_callback_handler_remove (void)
{
+ gdb_assert (current_ui == main_ui);
+
rl_callback_handler_remove ();
callback_handler_installed = 0;
}
void
gdb_rl_callback_handler_install (const char *prompt)
{
+ gdb_assert (current_ui == main_ui);
+
/* Calling rl_callback_handler_install resets readline's input
buffer. Calling this when we were already processing input
therefore loses input. */
gdb_assert (!callback_handler_installed);
- rl_callback_handler_install (prompt, input_handler);
+ rl_callback_handler_install (prompt, gdb_rl_callback_handler);
callback_handler_installed = 1;
}
void
gdb_rl_callback_handler_reinstall (void)
{
+ gdb_assert (current_ui == main_ui);
+
if (!callback_handler_installed)
{
/* Passing NULL as prompt argument tells readline to not display
IE, displayed but not set. */
if (! new_prompt)
{
- if (sync_execution)
+ struct ui *ui = current_ui;
+
+ if (ui->prompt_state == PROMPTED)
+ internal_error (__FILE__, __LINE__, _("double prompt"));
+ else if (ui->prompt_state == PROMPT_BLOCKED)
{
/* This is to trick readline into not trying to display the
prompt. Even though we display the prompt using this
the above two functions. Calling
rl_callback_handler_remove(), does the job. */
- gdb_rl_callback_handler_remove ();
+ if (current_ui->command_editing)
+ gdb_rl_callback_handler_remove ();
do_cleanups (old_chain);
return;
}
- else
+ else if (ui->prompt_state == PROMPT_NEEDED)
{
/* Display the top level prompt. */
actual_gdb_prompt = top_level_prompt ();
+ ui->prompt_state = PROMPTED;
}
}
else
actual_gdb_prompt = xstrdup (new_prompt);
- if (async_command_editing_p)
+ if (current_ui->command_editing)
{
gdb_rl_callback_handler_remove ();
gdb_rl_callback_handler_install (actual_gdb_prompt);
beginning. */
const char suffix[] = "\n\032\032prompt\n";
- return concat (prefix, prompt, suffix, NULL);
+ return concat (prefix, prompt, suffix, (char *) NULL);
}
return xstrdup (prompt);
}
-/* Get a pointer to the command line buffer. This is used to
+/* See top.h. */
+
+struct ui *main_ui;
+struct ui *current_ui;
+struct ui *ui_list;
+
+/* Get a pointer to the current UI's line buffer. This is used to
construct a whole line of input from partial input. */
static struct buffer *
get_command_line_buffer (void)
{
- static struct buffer line_buffer;
- static int line_buffer_initialized;
-
- if (!line_buffer_initialized)
- {
- buffer_init (&line_buffer);
- line_buffer_initialized = 1;
- }
-
- return &line_buffer;
+ return ¤t_ui->line_buffer;
}
/* When there is an event ready on the stdin file descriptor, instead
void
stdin_event_handler (int error, gdb_client_data client_data)
{
+ struct ui *ui = (struct ui *) client_data;
+
if (error)
{
- printf_unfiltered (_("error detected on stdin\n"));
- delete_file_handler (input_fd);
- /* If stdin died, we may as well kill gdb. */
- quit_command ((char *) 0, stdin == instream);
+ /* Switch to the main UI, so diagnostics always go there. */
+ current_ui = main_ui;
+
+ delete_file_handler (ui->input_fd);
+ if (main_ui == ui)
+ {
+ /* If stdin died, we may as well kill gdb. */
+ printf_unfiltered (_("error detected on stdin\n"));
+ quit_command ((char *) 0, 0);
+ }
+ else
+ {
+ /* Simply delete the UI. */
+ delete_ui (ui);
+ }
}
else
{
- /* This makes sure a ^C immediately followed by further input is
- always processed in that order. E.g,. with input like
- "^Cprint 1\n", the SIGINT handler runs, marks the async signal
- handler, and then select/poll may return with stdin ready,
- instead of -1/EINTR. The
- gdb.base/double-prompt-target-event-error.exp test exercises
- this. */
+ /* Switch to the UI whose input descriptor woke up the event
+ loop. */
+ current_ui = ui;
+
+ /* This makes sure a ^C immediately followed by further input is
+ always processed in that order. E.g,. with input like
+ "^Cprint 1\n", the SIGINT handler runs, marks the async
+ signal handler, and then select/poll may return with stdin
+ ready, instead of -1/EINTR. The
+ gdb.base/double-prompt-target-event-error.exp test exercises
+ this. */
QUIT;
do
{
call_stdin_event_handler_again_p = 0;
- (*call_readline) (client_data);
- } while (call_stdin_event_handler_again_p != 0);
+ ui->call_readline (client_data);
+ }
+ while (call_stdin_event_handler_again_p != 0);
}
}
+/* See top.h. */
+
+void
+ui_register_input_event_handler (struct ui *ui)
+{
+ add_file_handler (ui->input_fd, stdin_event_handler, ui);
+}
+
+/* See top.h. */
+
+void
+ui_unregister_input_event_handler (struct ui *ui)
+{
+ delete_file_handler (ui->input_fd);
+}
+
/* Re-enable stdin after the end of an execution command in
synchronous mode, or after an error from the target, and we aborted
the exec operation. */
void
async_enable_stdin (void)
{
- if (sync_execution)
+ struct ui *ui = current_ui;
+
+ if (ui->prompt_state == PROMPT_BLOCKED)
{
- /* See NOTE in async_disable_stdin(). */
- /* FIXME: cagney/1999-09-27: Call this before clearing
- sync_execution. Current target_terminal_ours() implementations
- check for sync_execution before switching the terminal. */
target_terminal_ours ();
- sync_execution = 0;
+ ui_register_input_event_handler (ui);
+ ui->prompt_state = PROMPT_NEEDED;
}
}
void
async_disable_stdin (void)
{
- sync_execution = 1;
+ struct ui *ui = current_ui;
+
+ ui->prompt_state = PROMPT_BLOCKED;
+ delete_file_handler (ui->input_fd);
}
\f
void
command_handler (char *command)
{
- struct cleanup *stat_chain;
+ struct ui *ui = current_ui;
char *c;
- if (instream == stdin)
+ if (ui->instream == ui->stdin_stream)
reinitialize_more_filter ();
- stat_chain = make_command_stats_cleanup (1);
+ scoped_command_stats stat_reporter (true);
/* Do not execute commented lines. */
for (c = command; *c == ' ' || *c == '\t'; c++)
;
if (c[0] != '#')
{
- execute_command (command, instream == stdin);
+ execute_command (command, ui->instream == ui->stdin_stream);
/* Do any commands attached to breakpoint we stopped at. */
bpstat_do_actions ();
}
-
- do_cleanups (stat_chain);
}
/* Append RL, an input line returned by readline or one of its
handle_line_of_input (struct buffer *cmd_line_buffer,
char *rl, int repeat, char *annotation_suffix)
{
+ struct ui *ui = current_ui;
+ int from_tty = ui->instream == ui->stdin_stream;
char *p1;
char *cmd;
command, but leave ownership of memory to the buffer . */
cmd_line_buffer->used_size = 0;
- if (annotation_level > 1 && instream == stdin)
+ if (from_tty && annotation_level > 1)
{
printf_unfiltered (("\n\032\032post-"));
puts_unfiltered (annotation_suffix);
}
/* Do history expansion if that is wished. */
- if (history_expansion_p && instream == stdin
- && ISATTY (instream))
+ if (history_expansion_p && from_tty && input_interactive_p (current_ui))
{
char *history_value;
int expanded;
and then later fetch it from the value history and remove the
'#'. The kill ring is probably better, but some people are in
the habit of commenting things out. */
- if (*cmd != '\0' && input_from_terminal_p ())
+ if (*cmd != '\0' && from_tty && input_interactive_p (current_ui))
gdb_add_history (cmd);
/* Save into global buffer if appropriate. */
command_line_handler (char *rl)
{
struct buffer *line_buffer = get_command_line_buffer ();
+ struct ui *ui = current_ui;
char *cmd;
- cmd = handle_line_of_input (line_buffer, rl, instream == stdin, "prompt");
+ cmd = handle_line_of_input (line_buffer, rl, 1, "prompt");
if (cmd == (char *) EOF)
{
/* stdin closed. The connection with the terminal is gone.
hung up but GDB is still alive. In such a case, we just quit
gdb killing the inferior program too. */
printf_unfiltered ("quit\n");
- execute_command ("quit", stdin == instream);
+ execute_command ("quit", 1);
}
else if (cmd == NULL)
{
}
else
{
+ ui->prompt_state = PROMPT_NEEDED;
+
command_handler (cmd);
- display_gdb_prompt (0);
+
+ if (ui->prompt_state != PROMPTED)
+ display_gdb_prompt (0);
}
}
char *result;
struct buffer line_buffer;
static int done_once = 0;
+ struct ui *ui = current_ui;
buffer_init (&line_buffer);
stream after '\n'. If we buffer the input and fgetc drains the
stream, getting stuff beyond the newline as well, a select, done
afterwards will not trigger. */
- if (!done_once && !ISATTY (instream))
+ if (!done_once && !ISATTY (ui->instream))
{
- setbuf (instream, NULL);
+ setbuf (ui->instream, NULL);
done_once = 1;
}
{
/* Read from stdin if we are executing a user defined command.
This is the right thing for prompt_for_continue, at least. */
- c = fgetc (instream ? instream : stdin);
+ c = fgetc (ui->instream != NULL ? ui->instream : ui->stdin_stream);
if (c == EOF)
{
break;
}
xfree (buffer_finish (&line_buffer));
- (*input_handler) (0);
+ ui->input_handler (NULL);
return;
}
buffer_grow_char (&line_buffer, '\0');
result = buffer_finish (&line_buffer);
- (*input_handler) (result);
+ ui->input_handler (result);
}
\f
static void
async_sigterm_handler (gdb_client_data arg)
{
- quit_force (NULL, stdin == instream);
+ quit_force (NULL, 0);
}
/* See defs.h. */
}
\f
-/* Called by do_setshow_command. */
-void
-set_async_editing_command (char *args, int from_tty,
- struct cmd_list_element *c)
-{
- change_line_handler ();
-}
-
/* Set things up for readline to be invoked via the alternate
- interface, i.e. via a callback function (rl_callback_read_char),
- and hook up instream to the event loop. */
+ interface, i.e. via a callback function
+ (gdb_rl_callback_read_char), and hook up instream to the event
+ loop. */
+
void
-gdb_setup_readline (void)
+gdb_setup_readline (int editing)
{
+ struct ui *ui = current_ui;
+
/* This function is a noop for the sync case. The assumption is
that the sync setup is ALL done in gdb_init, and we would only
mess it up here. The sync stuff should really go away over
time. */
if (!batch_silent)
- gdb_stdout = stdio_fileopen (stdout);
- gdb_stderr = stderr_fileopen ();
+ gdb_stdout = new stdio_file (ui->outstream);
+ gdb_stderr = new stderr_file (ui->errstream);
gdb_stdlog = gdb_stderr; /* for moment */
gdb_stdtarg = gdb_stderr; /* for moment */
gdb_stdtargerr = gdb_stderr; /* for moment */
- /* If the input stream is connected to a terminal, turn on
- editing. */
- if (ISATTY (instream))
+ /* If the input stream is connected to a terminal, turn on editing.
+ However, that is only allowed on the main UI, as we can only have
+ one instance of readline. */
+ if (ISATTY (ui->instream) && editing && ui == main_ui)
{
/* Tell gdb that we will be using the readline library. This
could be overwritten by a command in .gdbinit like 'set
editing on' or 'off'. */
- async_command_editing_p = 1;
-
+ ui->command_editing = 1;
+
/* When a character is detected on instream by select or poll,
readline will be invoked via this callback function. */
- call_readline = rl_callback_read_char_wrapper;
+ ui->call_readline = gdb_rl_callback_read_char_wrapper;
+
+ /* Tell readline to use the same input stream that gdb uses. */
+ rl_instream = ui->instream;
}
else
{
- async_command_editing_p = 0;
- call_readline = gdb_readline_no_editing_callback;
+ ui->command_editing = 0;
+ ui->call_readline = gdb_readline_no_editing_callback;
}
-
- /* When readline has read an end-of-line character, it passes the
- complete line to gdb for processing; command_line_handler is the
- function that does this. */
- input_handler = command_line_handler;
-
- /* Tell readline to use the same input stream that gdb uses. */
- rl_instream = instream;
-
- /* Get a file descriptor for the input stream, so that we can
- register it with the event loop. */
- input_fd = fileno (instream);
-
- /* Now we need to create the event sources for the input file
- descriptor. */
- /* At this point in time, this is the only event source that we
- register with the even loop. Another source is going to be the
- target program (inferior), but that must be registered only when
- it actually exists (I.e. after we say 'run' or after we connect
- to a remote target. */
- add_file_handler (input_fd, stdin_event_handler, 0);
+
+ /* Now create the event source for this UI's input file descriptor.
+ Another source is going to be the target program (inferior), but
+ that must be registered only when it actually exists (I.e. after
+ we say 'run' or after we connect to a remote target. */
+ ui_register_input_event_handler (ui);
}
/* Disable command input through the standard CLI channels. Used in
the suspend proc for interpreters that use the standard gdb readline
interface, like the cli & the mi. */
+
void
gdb_disable_readline (void)
{
+ struct ui *ui = current_ui;
+
/* FIXME - It is too heavyweight to delete and remake these every
time you run an interpreter that needs readline. It is probably
better to have the interpreters cache these, which in turn means
gdb_stdtargerr = NULL;
#endif
- gdb_rl_callback_handler_remove ();
- delete_file_handler (input_fd);
+ if (ui->command_editing)
+ gdb_rl_callback_handler_remove ();
+ delete_file_handler (ui->input_fd);
}
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