Catch exception in value_rtti_indirect_type

In the situation described in bug 17416 [1]:

  * "set print object" is on;
  * The variable object is a pointer to a struct, and it contains an
    invalid value (e.g. NULL, or random uninitialized value);
  * The variable object (struct) has a child which is also a pointer to a
    struct;
  * We try to use "-var-list-children".

... an exception thrown in value_ind can propagate too far and leave an
half-built variable object, leading to a wrong state. This patch adds a
TRY_CATCH to catch it and makes value_rtti_indirect_type return NULL in
that case, meaning that the type of the pointed object could not be
found.

A test for the fix is also added.

New in v2:

  * Added test.
  * Restructured "catch" code.
  * Added details about the bug in commit log.

gdb/Changelog:

	* valops.c (value_rtti_indirect_type): Catch exception thrown by
	value_ind.

gdb/testsuite/ChangeLog

	* gdb.mi/mi-var-list-children-invalid-grandchild.c: New file.
	* gdb.mi/mi-var-list-children-invalid-grandchild.exp: New file.

[1] https://sourceware.org/bugzilla/show_bug.cgi?id=17416

5 files changed, 140 insertions, 2 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index c195f5d..10c3855 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,9 @@
+2015-01-23  Simon Marchi  <simon.marchi@ericsson.com>
+
+	PR gdb/17416
+	* valops.c (value_rtti_indirect_type): Catch exception thrown by
+	value_ind.
+
 2015-01-15  Mark Wielaard  <mjw@redhat.com>
 
 	* dwarf2read.c (read_subroutine_type): Set TYPE_NO_RETURN from
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 5b53cdd..ba387ef 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2015-01-23  Simon Marchi  <simon.marchi@ericsson.com>
+
+	* gdb.mi/mi-var-list-children-invalid-grandchild.c: New file.
+	* gdb.mi/mi-var-list-children-invalid-grandchild.exp: New file.
+
 2015-01-15  Mark Wielaard  <mjw@redhat.com>
 
 	* gdb.base/noreturn-return.c: New file.
diff --git a/gdb/testsuite/gdb.mi/mi-var-list-children-invalid-grandchild.c b/gdb/testsuite/gdb.mi/mi-var-list-children-invalid-grandchild.c
new file mode 100644
index 0000000..ee5dd6e
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/mi-var-list-children-invalid-grandchild.c
@@ -0,0 +1,46 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2015 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+struct inner
+{
+  int a;
+};
+
+struct outer
+{
+  struct inner *inner;
+};
+
+int main (void)
+{
+  struct inner inner;
+  struct outer outer;
+  struct outer *p_outer;
+
+  inner.a = 42;
+  outer.inner = &inner;
+
+  /* We force p_outer to an invalid value, but this also happens naturally
+   * when a variable has not been initialized. */
+
+  p_outer = 0;
+  /* p_outer set to invalid value */
+  p_outer = &outer;
+  /* p_outer set to valid value */
+
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.mi/mi-var-list-children-invalid-grandchild.exp b/gdb/testsuite/gdb.mi/mi-var-list-children-invalid-grandchild.exp
new file mode 100644
index 0000000..cd5db8b
--- /dev/null
+++ b/gdb/testsuite/gdb.mi/mi-var-list-children-invalid-grandchild.exp
@@ -0,0 +1,63 @@
+# Copyright 2015 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# This is a regression test for bug 17416
+# https://sourceware.org/bugzilla/show_bug.cgi?id=17416
+
+load_lib mi-support.exp
+set MIFLAGS "-i=mi"
+
+gdb_exit
+if [mi_gdb_start] {
+    continue
+}
+
+standard_testfile
+
+if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
+    untested mi-var-list-children-invalid-grandchild.exp
+    return -1
+}
+
+mi_delete_breakpoints
+mi_gdb_reinitialize_dir $srcdir/$subdir
+mi_gdb_load ${binfile}
+
+set line_invalid_pointer_value [gdb_get_line_number "p_outer set to invalid value"]
+set line_valid_pointer_value [gdb_get_line_number "p_outer set to valid value"]
+
+# set print object on
+mi_gdb_test "-interpreter-exec console \"set print object on\"" \
+    "(.*=cmd-param-changed,param=\"print object\",value=\"on\".*|)\\^done" \
+    "set print object on"
+
+mi_runto main
+
+mi_continue_to_line $line_invalid_pointer_value "continue to invalid pointer value"
+
+# Create variable object
+mi_gdb_test "-var-create var1 * p_outer" "\\^done,name=\"var1\",numchild=\"1\",value=\"0x0\",type=\"struct outer \\*\",thread-id=\"1\",has_more=\"0\"" "create variable object"
+
+# List children while the pointer is uninitialized.
+# Note: if you remove this -var-list-children, the second one will work.
+mi_gdb_test "-var-list-children var1" "\\^done,numchild=\"1\",children=\\\[child={name=\"var1.inner\",exp=\"inner\",numchild=\"1\",type=\"struct inner \\*\",thread-id=\"1\"}\\\],has_more=\"0\"" "list children #1"
+
+mi_continue_to_line $line_valid_pointer_value "continue to valid pointer value"
+
+# Update and list children again
+mi_gdb_test "-var-update var1" "\\^done,changelist=\\\[{name=\"var1\",in_scope=\"true\",type_changed=\"false\",has_more=\"0\"},{name=\"var1.inner\",in_scope=\"true\",type_changed=\"false\",has_more=\"0\"}\\\]" "update variable object"
+
+mi_gdb_test "-var-list-children var1" "\\^done,numchild=\"1\",children=\\\[child={name=\"var1.inner\",exp=\"inner\",numchild=\"1\",type=\"struct inner \\*\",thread-id=\"1\"}\\\],has_more=\"0\"" "list children #2"
+
diff --git a/gdb/valops.c b/gdb/valops.c
index 27eda9f..8cbac85 100644
--- a/gdb/valops.c
+++ b/gdb/valops.c
@@ -3592,7 +3592,7 @@ struct type *
 value_rtti_indirect_type (struct value *v, int *full, 
 			  int *top, int *using_enc)
 {
-  struct value *target;
+  struct value *target = NULL;
   struct type *type, *real_type, *target_type;
 
   type = value_type (v);
@@ -3600,7 +3600,25 @@ value_rtti_indirect_type (struct value *v, int *full,
   if (TYPE_CODE (type) == TYPE_CODE_REF)
     target = coerce_ref (v);
   else if (TYPE_CODE (type) == TYPE_CODE_PTR)
-    target = value_ind (v);
+    {
+      volatile struct gdb_exception except;
+
+      TRY_CATCH (except, RETURN_MASK_ERROR)
+        {
+	  target = value_ind (v);
+        }
+      if (except.reason < 0)
+	{
+	  if (except.error == MEMORY_ERROR)
+	    {
+	      /* value_ind threw a memory error. The pointer is NULL or
+	         contains an uninitialized value: we can't determine any
+	         type.  */
+	      return NULL;
+	    }
+	  throw_exception (except);
+	}
+    }
   else
     return NULL;