[PATCH 1/2] Revert "kconfig: qconf: don't show goback button on splitMode"

[PATCH 1/2] Revert "kconfig: qconf: don't show goback button on splitMode"

[Masahiro Yamada]

This reverts commit cc1c08edccaf5317d99a17a3231fe06381044e83.

Maxim Levitsky reports 'make xconfig' crashes since that commit
(https://lkml.org/lkml/2020/7/18/411)

Or, the following is simple test code that makes it crash:

    menu "Menu"

    config FOO
            bool "foo"
            default y

    menuconfig BAR
            bool "bar"
            depends on FOO

    endmenu

Select the Split View mode, and double-click "bar" in the right window,
then you will see Segmentation fault.

When 'last' is not set for symbolMode, the following code in
ConfigList::updateList() calls firstChild().

  item = last ? last->nextSibling() : firstChild();

However, ConfigList::firstChild() does not seem to return a (ConfigItem *)
capable pointer, which seems another bug.

Moreover, we should reconsider whether hiding the goback icon is the
right thing to do.

In the following test code, the Split View shows "Menu2" and "Menu3" in
the right window. You can descend into "Menu3", but there is no way to
ascend back to "Menu2" from "Menu3".

    menu "Menu1"

    config FOO
            bool "foo"
            default y

    menu "Menu2"
            depends on FOO

    menu "Menu3"

    config BAZ
            bool "baz"

    endmenu

    endmenu

    endmenu

It is true that the goback button is currently not functional due to yet
another bug, but hiding the problem is not the right way to go.

Anyway, Segmentation fault is rather fatal. Revert the offending commit
for now, and we should find the right solution.

Reported-by:  Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/kconfig/qconf.cc | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/scripts/kconfig/qconf.cc b/scripts/kconfig/qconf.cc
index 4a616128a154..75c7b57fd7a9 100644
--- a/scripts/kconfig/qconf.cc
+++ b/scripts/kconfig/qconf.cc
@@ -437,10 +437,9 @@ void ConfigList::updateList(ConfigItem* item)
 	if (rootEntry != &rootmenu && (mode == singleMode ||
 	    (mode == symbolMode && rootEntry->parent != &rootmenu))) {
 		item = (ConfigItem *)topLevelItem(0);
-		if (!item && mode != symbolMode) {
+		if (!item)
 			item = new ConfigItem(this, 0, true);
-			last = item;
-		}
+		last = item;
 	}
 	if ((mode == singleMode || (mode == symbolMode && !(rootEntry->flags & MENU_ROOT))) &&
 	    rootEntry->sym && rootEntry->prompt) {
-- 
2.25.1

[PATCH 2/2] kconfig: qconf: remove wrong ConfigList::firstChild()

[Masahiro Yamada]

This function returns the first child object, but the returned pointer
is not compatible with (ConfigItem *).

Commit cc1c08edccaf ("kconfig: qconf: don't show goback button on
splitMode") uncovered this because using the pointer from this function
would make qconf crash. (https://lkml.org/lkml/2020/7/18/411)

This function does not work. Do not use it.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/kconfig/qconf.cc | 2 +-
 scripts/kconfig/qconf.h  | 4 ----
 2 files changed, 1 insertion(+), 5 deletions(-)

diff --git a/scripts/kconfig/qconf.cc b/scripts/kconfig/qconf.cc
index 75c7b57fd7a9..80f042a337c2 100644
--- a/scripts/kconfig/qconf.cc
+++ b/scripts/kconfig/qconf.cc
@@ -443,7 +443,7 @@ void ConfigList::updateList(ConfigItem* item)
 	}
 	if ((mode == singleMode || (mode == symbolMode && !(rootEntry->flags & MENU_ROOT))) &&
 	    rootEntry->sym && rootEntry->prompt) {
-		item = last ? last->nextSibling() : firstChild();
+		item = last ? last->nextSibling() : nullptr;
 		if (!item)
 			item = new ConfigItem(this, last, rootEntry, true);
 		else
diff --git a/scripts/kconfig/qconf.h b/scripts/kconfig/qconf.h
index fb9e9729266f..5eeab4a8bb43 100644
--- a/scripts/kconfig/qconf.h
+++ b/scripts/kconfig/qconf.h
@@ -92,10 +92,6 @@ public slots:
 	{
 		return this;
 	}
-	ConfigItem* firstChild() const
-	{
-		return (ConfigItem *)children().first();
-	}
 	void addColumn(colIdx idx)
 	{
 		showColumn(idx);
-- 
2.25.1