[PATCH 0/2] Fix two TUI crashes

[PATCH 0/2] Fix two TUI crashes

[Tom Tromey]

This short series fixes a couple of crashes involving the TUI.

Tom

[PATCH 1/2] Fix C-x 1 from gdb prompt

[Tom Tromey]

Pedro pointed out on irc that C-x 1 from the gdb prompt will cause a
crash.  This happened because of a bug in remove_windows -- it would
always remove all the windows from the layout.  This patch fixes this
bug, and also arranges to have C-x 1 preserve the status window.

gdb/ChangeLog
2020-06-06  Tom Tromey  <tom@tromey.com>

	* tui/tui-layout.c (tui_layout_split::remove_windows): Fix logic.
	Also preserve the status window.
---
 gdb/ChangeLog        |  5 +++++
 gdb/tui/tui-layout.c | 11 ++++++-----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/gdb/tui/tui-layout.c b/gdb/tui/tui-layout.c
index 491ce275acb..b87d21eb6de 100644
--- a/gdb/tui/tui-layout.c
+++ b/gdb/tui/tui-layout.c
@@ -790,13 +790,14 @@ tui_layout_split::remove_windows (const char *name)
       const char *this_name = m_splits[i].layout->get_name ();
       if (this_name == nullptr)
 	m_splits[i].layout->remove_windows (name);
+      else if (strcmp (this_name, name) == 0
+	       || strcmp (this_name, "cmd") == 0
+	       || strcmp (this_name, "status") == 0)
+	{
+	  /* Keep.  */
+	}
       else
 	{
-	  if (strcmp (this_name, name) == 0
-	      || strcmp (this_name, "cmd") == 0)
-	    {
-	      /* Keep.  */
-	    }
 	  m_splits.erase (m_splits.begin () + i);
 	  --i;
 	}
-- 
2.17.2

[PATCH 2/2] Fix crash when exiting TUI with gdb -tui

[Tom Tromey]

PR tui/25348 points out that, when "gdb -tui" is used, then exiting
the TUI will cause a crash.

This happens because tui_setup_io stashes some readline variables --
but because this happens before readline is initialized, some of these
are NULL.  Then, when exiting the TUI, the NULL values are "restored",
causing a crash in readline.

This patch fixes the problem by ensuring that readline is initialized
first.  Back in commit 11061048d ("Give a name to the TUI SingleKey
keymap"), a call to rl_initialize was removed from
tui_initialize_readline; this patch resurrects the call, but moves it
to the end of the function, so as not to remove the ability to modify
the SingleKey map from .inputrc.

gdb/ChangeLog
2020-06-06  Tom Tromey  <tom@tromey.com>

	PR tui/25348:
	* tui/tui.c (tui_initialize_readline): Only run once.  Call
	rl_initialize.
	* tui/tui-io.c (tui_setup_io): Call tui_initialize_readline.
---
 gdb/ChangeLog    | 7 +++++++
 gdb/tui/tui-io.c | 4 ++++
 gdb/tui/tui.c    | 9 +++++++++
 3 files changed, 20 insertions(+)

diff --git a/gdb/tui/tui-io.c b/gdb/tui/tui-io.c
index e7a8ac77bce..75fab1f8e91 100644
--- a/gdb/tui/tui-io.c
+++ b/gdb/tui/tui-io.c
@@ -746,6 +746,10 @@ tui_setup_io (int mode)
 
   if (mode)
     {
+      /* Ensure that readline has been initialized before saving any
+	 of its variables.  */
+      tui_initialize_readline ();
+
       /* Redirect readline to TUI.  */
       tui_old_rl_redisplay_function = rl_redisplay_function;
       tui_old_rl_deprep_terminal = rl_deprep_term_function;
diff --git a/gdb/tui/tui.c b/gdb/tui/tui.c
index ac435d16d6c..50f846d4090 100644
--- a/gdb/tui/tui.c
+++ b/gdb/tui/tui.c
@@ -270,6 +270,12 @@ tui_set_key_mode (enum tui_key_mode mode)
 void
 tui_initialize_readline (void)
 {
+  static bool initialized;
+
+  if (initialized)
+    return;
+  initialized = true;
+
   int i;
   Keymap tui_ctlx_keymap;
 
@@ -325,6 +331,9 @@ tui_initialize_readline (void)
   rl_bind_key_in_map ('q', tui_rl_next_keymap, tui_keymap);
   rl_bind_key_in_map ('s', tui_rl_next_keymap, emacs_ctlx_keymap);
   rl_bind_key_in_map ('s', tui_rl_next_keymap, tui_ctlx_keymap);
+
+  /* Initialize readline after the above.  */
+  rl_initialize ();
 }
 
 /* Return the TERM variable from the environment, or "<unset>"
-- 
2.17.2

Re: [PATCH 2/2] Fix crash when exiting TUI with gdb -tui

[Christian Biesinger]

On Sat, Jun 6, 2020 at 3:13 PM Tom Tromey <tom@tromey.com> wrote:
> --- a/gdb/tui/tui.c
> +++ b/gdb/tui/tui.c
> @@ -270,6 +270,12 @@ tui_set_key_mode (enum tui_key_mode mode)
>  void
>  tui_initialize_readline (void)
>  {
> +  static bool initialized;
> +
> +  if (initialized)
> +    return;
> +  initialized = true;

Would it make sense to rename this function to
tui_ensure_readline_initialized() or something, to make it clear that
it can be called more than once?

Christian

Re: [PATCH 1/2] Fix C-x 1 from gdb prompt

[Christian Biesinger]

On Sat, Jun 6, 2020 at 3:13 PM Tom Tromey <tom@tromey.com> wrote:
> +      else if (strcmp (this_name, name) == 0
> +              || strcmp (this_name, "cmd") == 0
> +              || strcmp (this_name, "status") == 0)

Maybe those strings should be constants somewhere?

Christian

Re: [PATCH 1/2] Fix C-x 1 from gdb prompt

[Tom Tromey]

>>>>> "Christian" == Christian Biesinger <cbiesinger@google.com> writes:

Christian> On Sat, Jun 6, 2020 at 3:13 PM Tom Tromey <tom@tromey.com> wrote:
>> +      else if (strcmp (this_name, name) == 0
>> +              || strcmp (this_name, "cmd") == 0
>> +              || strcmp (this_name, "status") == 0)

Christian> Maybe those strings should be constants somewhere?

Most of them were constants in tui-data.h already.
I thought I'd tack this patch on to the end of the series.

Tom

commit 9aaf1b1b02745ee803dcfa2b7bf91add2cf0a6ea
Author: Tom Tromey <tom@tromey.com>
Date:   Thu Jun 11 18:19:12 2020 -0600

    Use macros for TUI window names
    
    Christian pointed out that tui-layout.c hard-codes various window
    names.  This patch changes the code to use the macros from tui-data.h
    instead.  For each window, I searched for uses of the name; but I only
    found any in tui-layout.c.  This also adds a new macro to account for
    the "status" window.
    
    gdb/ChangeLog
    2020-06-11  Tom Tromey  <tom@tromey.com>
    
            * tui/tui-data.h (STATUS_NAME): New macro.
            * tui/tui-layout.c (tui_remove_some_windows)
            (initialize_known_windows, tui_register_window)
            (tui_layout_split::remove_windows, initialize_layouts)
            (tui_new_layout_command): Don't use hard-coded window names.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index cd6ff0b8fe8..f674fef7e16 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,11 @@
+2020-06-11  Tom Tromey  <tom@tromey.com>
+
+	* tui/tui-data.h (STATUS_NAME): New macro.
+	* tui/tui-layout.c (tui_remove_some_windows)
+	(initialize_known_windows, tui_register_window)
+	(tui_layout_split::remove_windows, initialize_layouts)
+	(tui_new_layout_command): Don't use hard-coded window names.
+
 2020-06-06  Tom Tromey  <tom@tromey.com>
 
 	PR tui/25348:
diff --git a/gdb/tui/tui-data.h b/gdb/tui/tui-data.h
index 2dc73b963da..abe77272291 100644
--- a/gdb/tui/tui-data.h
+++ b/gdb/tui/tui-data.h
@@ -130,6 +130,7 @@ struct tui_gen_win_info
 #define CMD_NAME                "cmd"
 #define DATA_NAME               "regs"
 #define DISASSEM_NAME           "asm"
+#define STATUS_NAME		"status"
 #define MIN_WIN_HEIGHT          3
 #define MIN_CMD_WIN_HEIGHT      3
 
diff --git a/gdb/tui/tui-layout.c b/gdb/tui/tui-layout.c
index b87d21eb6de..8164b346370 100644
--- a/gdb/tui/tui-layout.c
+++ b/gdb/tui/tui-layout.c
@@ -255,7 +255,7 @@ tui_remove_some_windows ()
 {
   tui_win_info *focus = tui_win_with_focus ();
 
-  if (strcmp (focus->name (), "cmd") == 0)
+  if (strcmp (focus->name (), CMD_NAME) == 0)
     {
       /* Try leaving the source or disassembly window.  If neither
 	 exists, just do nothing.  */
@@ -373,18 +373,18 @@ initialize_known_windows ()
 {
   known_window_types = new std::unordered_map<std::string, window_factory>;
 
-  known_window_types->emplace ("src",
+  known_window_types->emplace (SRC_NAME,
 			       make_standard_window<SRC_WIN,
 						    tui_source_window>);
-  known_window_types->emplace ("cmd",
+  known_window_types->emplace (CMD_NAME,
 			       make_standard_window<CMD_WIN, tui_cmd_window>);
-  known_window_types->emplace ("regs",
+  known_window_types->emplace (DATA_NAME,
 			       make_standard_window<DATA_WIN,
 						    tui_data_window>);
-  known_window_types->emplace ("asm",
+  known_window_types->emplace (DISASSEM_NAME,
 			       make_standard_window<DISASSEM_WIN,
 						    tui_disasm_window>);
-  known_window_types->emplace ("status", get_locator_window);
+  known_window_types->emplace (STATUS_NAME, get_locator_window);
 }
 
 /* See tui-layout.h.  */
@@ -394,8 +394,8 @@ tui_register_window (const char *name, window_factory &&factory)
 {
   std::string name_copy = name;
 
-  if (name_copy == "src" || name_copy == "cmd" || name_copy == "regs"
-      || name_copy == "asm" || name_copy == "status")
+  if (name_copy == SRC_NAME || name_copy == CMD_NAME || name_copy == DATA_NAME
+      || name_copy == DISASSEM_NAME || name_copy == STATUS_NAME)
     error (_("Window type \"%s\" is built-in"), name);
 
   known_window_types->emplace (std::move (name_copy),
@@ -791,8 +791,8 @@ tui_layout_split::remove_windows (const char *name)
       if (this_name == nullptr)
 	m_splits[i].layout->remove_windows (name);
       else if (strcmp (this_name, name) == 0
-	       || strcmp (this_name, "cmd") == 0
-	       || strcmp (this_name, "status") == 0)
+	       || strcmp (this_name, CMD_NAME) == 0
+	       || strcmp (this_name, STATUS_NAME) == 0)
 	{
 	  /* Keep.  */
 	}
@@ -888,37 +888,37 @@ initialize_layouts ()
   tui_layout_split *layout;
 
   layout = new tui_layout_split ();
-  layout->add_window ("src", 2);
-  layout->add_window ("status", 0);
-  layout->add_window ("cmd", 1);
-  add_layout_command ("src", layout);
+  layout->add_window (SRC_NAME, 2);
+  layout->add_window (STATUS_NAME, 0);
+  layout->add_window (CMD_NAME, 1);
+  add_layout_command (SRC_NAME, layout);
 
   layout = new tui_layout_split ();
-  layout->add_window ("asm", 2);
-  layout->add_window ("status", 0);
-  layout->add_window ("cmd", 1);
-  add_layout_command ("asm", layout);
+  layout->add_window (DISASSEM_NAME, 2);
+  layout->add_window (STATUS_NAME, 0);
+  layout->add_window (CMD_NAME, 1);
+  add_layout_command (DISASSEM_NAME, layout);
 
   layout = new tui_layout_split ();
-  layout->add_window ("src", 1);
-  layout->add_window ("asm", 1);
-  layout->add_window ("status", 0);
-  layout->add_window ("cmd", 1);
+  layout->add_window (SRC_NAME, 1);
+  layout->add_window (DISASSEM_NAME, 1);
+  layout->add_window (STATUS_NAME, 0);
+  layout->add_window (CMD_NAME, 1);
   add_layout_command ("split", layout);
 
   layout = new tui_layout_split ();
-  layout->add_window ("regs", 1);
-  layout->add_window ("src", 1);
-  layout->add_window ("status", 0);
-  layout->add_window ("cmd", 1);
+  layout->add_window (DATA_NAME, 1);
+  layout->add_window (SRC_NAME, 1);
+  layout->add_window (STATUS_NAME, 0);
+  layout->add_window (CMD_NAME, 1);
   layouts.emplace_back (layout);
   src_regs_layout = layout;
 
   layout = new tui_layout_split ();
-  layout->add_window ("regs", 1);
-  layout->add_window ("asm", 1);
-  layout->add_window ("status", 0);
-  layout->add_window ("cmd", 1);
+  layout->add_window (DATA_NAME, 1);
+  layout->add_window (DISASSEM_NAME, 1);
+  layout->add_window (STATUS_NAME, 0);
+  layout->add_window (CMD_NAME, 1);
   layouts.emplace_back (layout);
   asm_regs_layout = layout;
 }
@@ -1010,8 +1010,8 @@ tui_new_layout_command (const char *spec, int from_tty)
     error (_("Missing '}' in layout specification"));
   if (seen_windows.empty ())
     error (_("New layout does not contain any windows"));
-  if (seen_windows.find ("cmd") == seen_windows.end ())
-    error (_("New layout does not contain the \"cmd\" window"));
+  if (seen_windows.find (CMD_NAME) == seen_windows.end ())
+    error (_("New layout does not contain the \"" CMD_NAME "\" window"));
 
   gdb::unique_xmalloc_ptr<char> cmd_name
     = make_unique_xstrdup (new_name.c_str ());

Re: [PATCH 2/2] Fix crash when exiting TUI with gdb -tui

[Tom Tromey]

>>>>> "Christian" == Christian Biesinger <cbiesinger@google.com> writes:

Christian> On Sat, Jun 6, 2020 at 3:13 PM Tom Tromey <tom@tromey.com> wrote:
>> --- a/gdb/tui/tui.c
>> +++ b/gdb/tui/tui.c
>> @@ -270,6 +270,12 @@ tui_set_key_mode (enum tui_key_mode mode)
>> void
>> tui_initialize_readline (void)
>> {
>> +  static bool initialized;
>> +
>> +  if (initialized)
>> +    return;
>> +  initialized = true;

Christian> Would it make sense to rename this function to
Christian> tui_ensure_readline_initialized() or something, to make it clear that
Christian> it can be called more than once?

Makes sense.  I made this change.

Tom

Re: [PATCH 0/2] Fix two TUI crashes

[Pedro Alves]

On 6/6/20 9:12 PM, Tom Tromey wrote:
> This short series fixes a couple of crashes involving the TUI.

LGTM.  Thanks for fixing this.

Pedro Alves