Re: [PATCH] tui: don't overwrite a subprompt line that was given no input

[Patrick Palka <patrick at parcs dot ath dot cx>]

On Fri, 21 Aug 2015, Pedro Alves wrote:

> On 08/21/2015 05:45 PM, Patrick Palka wrote:
> > This patch fixes the following bug in TUI:
> >
> >   (gdb) break foo
> >   No symbol table is loaded.  Use the "file" command.
> >   Make breakpoint pending on future shared library load? (y or [n]) <ENTER>
> >
> > By submitting an empty command line to a subprompt, the subprompt line
> > is undesirably cleared and overwritten.  Outside of a subprompt,
> > clearing the prompt line after submitting an empty command line is
> > intended behavior which complements GDB's repeat-command shorthand.  But
> > inside a subprompt, this behavior is undesired since the shorthand is
> > not applicable in that case.  We should retain the subprompt line even
> > when it's given to input.
> >
> > This patch makes sure that a prompt given an empty command line is
> > cleared and overwritten only if it's not a subprompt.  To acheive this,
> > a new predicate is defined which informs us whether the current input
> > handler is a subprompt.
> >
> > gdb/ChangeLog:
> >
> > 	* top.h (gdb_in_subprompt_p): Declare.
> > 	* top.c (gdb_subprompt_depth): Define.
> > 	(gdb_in_subprompt_p): Define.
> > 	(gdb_readline_wrapper_cleanup): Decrement gdb_subprompt_depth.
> > 	(gdb_readline_wrapper): Increment gdb_subprompt_depth.
> > 	* tui/tui-io.c (tui_getc): Don't clear the prompt line if we
> > 	are in a subprompt.
>
> OK, but should really be s/subprompt/secondary prompt/ everywhere.

Done.  Here is what I'll commit.

-- >8 --

Subject: [PATCH] tui: don't overwrite a secondary prompt that was given no
 input

This patch fixes the following bug in TUI:

  (gdb) break foo
  No symbol table is loaded.  Use the "file" command.
  Make breakpoint pending on future shared library load? (y or [n]) <ENTER>

By submitting an empty command line to a secondary prompt, the line
corresponding to the secondary prompt is undesirably cleared and
overwritten.  Outside of a secondary prompt, clearing the prompt line
after submitting an empty command line is intended behavior which
complements GDB's repeat-command shorthand.  But inside a secondary
prompt, this behavior is undesired since the shorthand is not applicable
in that case.  We should retain the secondary-prompt line even when it's
given no input.

This patch makes sure that a prompt that was given an empty command line
is cleared and overwritten only if it's not a secondary prompt.  To
acheive this, a new predicate is defined which informs us whether the
current input handler is a secondary prompt.

gdb/ChangeLog:

	* top.h (gdb_in_secondary_prompt_p): Declare.
	* top.c (gdb_secondary_prompt_depth): Define.
	(gdb_in_secondary_prompt_p): Define.
	(gdb_readline_wrapper_cleanup): Decrement
	gdb_secondary_prompt_depth.
	(gdb_readline_wrapper): Increment gdb_secondary_prompt_depth.
	* tui/tui-io.c (tui_getc): Don't clear the prompt line if we
	are in a secondary prompt.
---
 gdb/top.c        | 18 ++++++++++++++++++
 gdb/top.h        |  4 ++++
 gdb/tui/tui-io.c |  2 +-
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/gdb/top.c b/gdb/top.c
index 061b52f..cb3c761 100644
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -754,6 +754,21 @@ static char *gdb_readline_wrapper_result;
    return.  */
 static void (*saved_after_char_processing_hook) (void);

+
+/* The number of nested readline secondary prompts that are currently
+   active.  */
+
+static int gdb_secondary_prompt_depth = 0;
+
+/* See top.h.  */
+
+int
+gdb_in_secondary_prompt_p (void)
+{
+  return gdb_secondary_prompt_depth > 0;
+}
+
+
 /* This function is called when readline has seen a complete line of
    text.  */

@@ -808,6 +823,8 @@ gdb_readline_wrapper_cleanup (void *arg)

   gdb_readline_wrapper_result = NULL;
   gdb_readline_wrapper_done = 0;
+  gdb_secondary_prompt_depth--;
+  gdb_assert (gdb_secondary_prompt_depth >= 0);

   after_char_processing_hook = saved_after_char_processing_hook;
   saved_after_char_processing_hook = NULL;
@@ -833,6 +850,7 @@ gdb_readline_wrapper (const char *prompt)

   cleanup->target_is_async_orig = target_is_async_p ();

+  gdb_secondary_prompt_depth++;
   back_to = make_cleanup (gdb_readline_wrapper_cleanup, cleanup);

   if (cleanup->target_is_async_orig)
diff --git a/gdb/top.h b/gdb/top.h
index 987279b..914a272 100644
--- a/gdb/top.h
+++ b/gdb/top.h
@@ -65,6 +65,10 @@ extern char *get_prompt (void);
    by gdb for its command prompt.  */
 extern void set_prompt (const char *s);

+/* Return 1 if the current input handler is a secondary prompt, 0 otherwise.  */
+
+extern int gdb_in_secondary_prompt_p (void);
+
 /* From random places.  */
 extern int readnow_symbol_files;

diff --git a/gdb/tui/tui-io.c b/gdb/tui/tui-io.c
index bca1f58..c7a092f 100644
--- a/gdb/tui/tui-io.c
+++ b/gdb/tui/tui-io.c
@@ -585,7 +585,7 @@ tui_getc (FILE *fp)
          with empty lines with gdb prompt at beginning.  Instead of that,
          stay on the same line but provide a visual effect to show the
          user we recognized the command.  */
-      if (rl_end == 0)
+      if (rl_end == 0 && !gdb_in_secondary_prompt_p ())
         {
 	  wmove (w, getcury (w), 0);

--
2.5.0.417.g69c5dbd.dirty