Re: GDB/MI and ">" prompts

Eli Zaretskii
2012-04-22T16:04:29Z

[I moved this to gdb-patches, since I propose a patch below.]

> Date: Thu, 19 Apr 2012 22:24:53 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: gdb@sourceware.org
>
> The crux of my question was why non-interactive mode does display a
> prompt while the interactive one doesn't.

To answer my own question, here's why:

char *
command_line_input (char *prompt_arg, int repeat, char *annotation_suffix)
{
...
/* Don't use fancy stuff if not talking to stdin. */
if (deprecated_readline_hook && input_from_terminal_p ())
{
rl = (*deprecated_readline_hook) (local_prompt);
}
else if (command_editing_p && input_from_terminal_p ())
{
rl = gdb_readline_wrapper (local_prompt);
}
else
{
rl = gdb_readline (local_prompt);
}

Now, the code is clear, but I cannot say I understand the logic. If
the input is from terminal, we ask (inside gdb_readline_wrapper) the
current interpreter whether to show the prompt. But if input is _not_
from terminal, we display the prompt unconditionally (inside
gdb_readline). How does this make sense?

> Date: Thu, 19 Apr 2012 11:53:29 -0700
> From: Joel Brobecker <brobecker@adacore.com>
> Cc: gdb@sourceware.org
>
> The other thing that occured to me was that, perhaps, we should instead
> be switching the interpreter while executing the console command,

I arrived to the same conclusion, eventually. See below.

> but I doubt that would be correct.

Why not? The patch below works for me.

--- gdb/interps.c~0 2012-01-06 06:43:17.000000000 +0200
+++ gdb/interps.c 2012-04-22 08:55:27.056588400 +0300
@@ -253,6 +253,18 @@ interp_ui_out (struct interp *interp)
return current_interpreter->procs->ui_out_proc (current_interpreter);
}

+/* Temporarily overrides the current interpreter. */
+struct interp *
+interp_set_temp (const char *name)
+{
+ struct interp *interp = interp_lookup (name);
+ struct interp *old_interp = current_interpreter;
+
+ if (interp)
+ current_interpreter = interp;
+ return old_interp;
+}
+
/* Returns the interpreter's cookie. */

void *
--- gdb/interps.h~0 2012-01-06 06:43:17.000000000 +0200
+++ gdb/interps.h 2012-04-22 08:42:05.687879800 +0300
@@ -69,6 +69,7 @@
extern struct ui_out *interp_ui_out (struct interp *interp);
extern void *interp_data (struct interp *interp);
extern const char *interp_name (struct interp *interp);
+extern struct interp *interp_set_temp (const char *name);

extern int current_interp_named_p (const char *name);
extern int current_interp_display_prompt_p (void);
--- gdb/cli/cli-script.c~0 2012-01-06 06:43:32.000000000 +0200
+++ gdb/cli/cli-script.c 2012-04-22 09:04:23.533807200 +0300
@@ -1178,6 +1178,12 @@ recurse_read_control_structure (char * (
return ret;
}

+static void
+restore_interp (void *arg)
+{
+ interp_set_temp (interp_name ((struct interp *)arg));
+}
+
/* Read lines from the input stream and accumulate them in a chain of
struct command_line's, which is then returned. For input from a
terminal, the special command "end" is used to mark the end of the
@@ -1210,8 +1216,21 @@ read_command_lines (char *prompt_arg, in
}
}

- head = read_command_lines_1 (read_next_line, parse_commands,
- validator, closure);
+
+ /* Reading commands assumes the CLI behavior, so temporarily
+ override the current interpreter with CLI. */
+ if (current_interp_named_p (INTERP_CONSOLE))
+ head = read_command_lines_1 (read_next_line, parse_commands,
+ validator, closure);
+ else
+ {
+ struct interp *old_interp = interp_set_temp (INTERP_CONSOLE);
+ struct cleanup *old_chain = make_cleanup (restore_interp, old_interp);
+
+ head = read_command_lines_1 (read_next_line, parse_commands,
+ validator, closure);
+ do_cleanups (old_chain);
+ }

if (deprecated_readline_end_hook && from_tty && input_from_terminal_p ())
{