Avoid undefined behavior in Guile exception handling

The Guile code will longjmp (via scm_throw) when an object requiring
destruction is on the stack.  This is undefined behavior.

This changes this code to run any destructors in inner scopes, and to
pass a POD to gdbscm_throw_gdb_exception.

gdb/ChangeLog
2019-04-25  Tom Tromey  <tromey@adacore.com>

	* guile/scm-exception.c (gdbscm_scm_from_gdb_exception)
	(gdbscm_throw_gdb_exception): Take a gdbscm_gdb_exception.
	* guile/scm-block.c, guile/scm-breakpoint.c, guile/scm-cmd.c,
	guile/scm-disasm.c, guile/scm-frame.c, guile/scm-lazy-string.c,
	guile/scm-math.c, guile/scm-param.c, guile/scm-ports.c,
	guile/scm-symbol.c, guile/scm-symtab.c, guile/scm-type.c,
	guile/scm-value.c: Use unpack.
	* guile/guile-internal.h (gdbscm_scm_from_gdb_exception): Take a
	gdbscm_gdb_exception.
	(gdbscm_throw_gdb_exception): Likewise.
	(struct gdbscm_gdb_exception): New.
	(unpack): New function.
	(gdbscm_wrap): Use unpack.

1 files changed, 23 insertions, 10 deletions

diff --git a/gdb/guile/scm-breakpoint.c b/gdb/guile/scm-breakpoint.c
index f86c263..9a4efee 100644
--- a/gdb/guile/scm-breakpoint.c
+++ b/gdb/guile/scm-breakpoint.c
@@ -411,7 +411,7 @@ gdbscm_register_breakpoint_x (SCM self)
 {
   breakpoint_smob *bp_smob
     = bpscm_get_breakpoint_smob_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
-  struct gdb_exception except;
+  gdbscm_gdb_exception except {};
   const char *location, *copy;
 
   /* We only support registering breakpoints created with make-breakpoint.  */
@@ -467,7 +467,7 @@ gdbscm_register_breakpoint_x (SCM self)
     }
   catch (const gdb_exception &ex)
     {
-      except = ex;
+      except = unpack (ex);
     }
 
   /* Ensure this gets reset, even if there's an error.  */
@@ -489,15 +489,17 @@ gdbscm_delete_breakpoint_x (SCM self)
   breakpoint_smob *bp_smob
     = bpscm_get_valid_breakpoint_smob_arg_unsafe (self, SCM_ARG1, FUNC_NAME);
 
+  gdbscm_gdb_exception exc {};
   try
     {
       delete_breakpoint (bp_smob->bp);
     }
   catch (const gdb_exception &except)
     {
-      GDBSCM_HANDLE_GDB_EXCEPTION (except);
+      exc = unpack (except);
     }
 
+  GDBSCM_HANDLE_GDB_EXCEPTION (exc);
   return SCM_UNSPECIFIED;
 }
 
@@ -586,6 +588,7 @@ gdbscm_set_breakpoint_enabled_x (SCM self, SCM newvalue)
   SCM_ASSERT_TYPE (gdbscm_is_bool (newvalue), newvalue, SCM_ARG2, FUNC_NAME,
 		   _("boolean"));
 
+  gdbscm_gdb_exception exc {};
   try
     {
       if (gdbscm_is_true (newvalue))
@@ -595,9 +598,10 @@ gdbscm_set_breakpoint_enabled_x (SCM self, SCM newvalue)
     }
   catch (const gdb_exception &except)
     {
-      GDBSCM_HANDLE_GDB_EXCEPTION (except);
+      exc = unpack (except);
     }
 
+  GDBSCM_HANDLE_GDB_EXCEPTION (exc);
   return SCM_UNSPECIFIED;
 }
 
@@ -623,15 +627,17 @@ gdbscm_set_breakpoint_silent_x (SCM self, SCM newvalue)
   SCM_ASSERT_TYPE (gdbscm_is_bool (newvalue), newvalue, SCM_ARG2, FUNC_NAME,
 		   _("boolean"));
 
+  gdbscm_gdb_exception exc {};
   try
     {
       breakpoint_set_silent (bp_smob->bp, gdbscm_is_true (newvalue));
     }
   catch (const gdb_exception &except)
     {
-      GDBSCM_HANDLE_GDB_EXCEPTION (except);
+      exc = unpack (except);
     }
 
+  GDBSCM_HANDLE_GDB_EXCEPTION (exc);
   return SCM_UNSPECIFIED;
 }
 
@@ -663,15 +669,17 @@ gdbscm_set_breakpoint_ignore_count_x (SCM self, SCM newvalue)
   if (value < 0)
     value = 0;
 
+  gdbscm_gdb_exception exc {};
   try
     {
       set_ignore_count (bp_smob->number, (int) value, 0);
     }
   catch (const gdb_exception &except)
     {
-      GDBSCM_HANDLE_GDB_EXCEPTION (except);
+      exc = unpack (except);
     }
 
+  GDBSCM_HANDLE_GDB_EXCEPTION (exc);
   return SCM_UNSPECIFIED;
 }
 
@@ -783,15 +791,17 @@ gdbscm_set_breakpoint_task_x (SCM self, SCM newvalue)
     {
       id = scm_to_long (newvalue);
 
+      gdbscm_gdb_exception exc {};
       try
 	{
 	  valid_id = valid_task_id (id);
 	}
       catch (const gdb_exception &except)
 	{
-	  GDBSCM_HANDLE_GDB_EXCEPTION (except);
+	  exc = unpack (except);
 	}
 
+      GDBSCM_HANDLE_GDB_EXCEPTION (exc);
       if (! valid_id)
 	{
 	  gdbscm_out_of_range_error (FUNC_NAME, SCM_ARG2, newvalue,
@@ -803,15 +813,17 @@ gdbscm_set_breakpoint_task_x (SCM self, SCM newvalue)
   else
     SCM_ASSERT_TYPE (0, newvalue, SCM_ARG2, FUNC_NAME, _("integer or #f"));
 
+  gdbscm_gdb_exception exc {};
   try
     {
       breakpoint_set_task (bp_smob->bp, id);
     }
   catch (const gdb_exception &except)
     {
-      GDBSCM_HANDLE_GDB_EXCEPTION (except);
+      exc = unpack (except);
     }
 
+  GDBSCM_HANDLE_GDB_EXCEPTION (exc);
   return SCM_UNSPECIFIED;
 }
 
@@ -968,17 +980,18 @@ gdbscm_breakpoint_commands (SCM self)
   string_file buf;
 
   current_uiout->redirect (&buf);
+  gdbscm_gdb_exception exc {};
   try
     {
       print_command_lines (current_uiout, breakpoint_commands (bp), 0);
     }
   catch (const gdb_exception &except)
     {
-      current_uiout->redirect (NULL);
-      gdbscm_throw_gdb_exception (except);
+      exc = unpack (except);
     }
 
   current_uiout->redirect (NULL);
+  GDBSCM_HANDLE_GDB_EXCEPTION (exc);
   result = gdbscm_scm_from_c_string (buf.c_str ());
 
   return result;