[PATCH 2/2] Avoid undefined behavior in gdbscm_make_breakpoint

[Pedro Alves <pedro@palves.net>]

Running gdb.guile/scm-breakpoint.exp against an --enable-ubsan build,
we see:

 UNRESOLVED: gdb.guile/scm-breakpoint.exp: test_watchpoints: create a breakpoint with an invalid type number
 ...
 guile (define wp2 (make-breakpoint "result" #:wp-class WP_WRITE #:type 999))
 ../../src/gdb/guile/scm-breakpoint.c:377:11: runtime error: load of value 999, which is not a valid value for type 'bptype'
 ERROR: GDB process no longer exists

Fix this by parsing the user/guile input as plain int, and cast to
internal type only after we know we have a number that would be valid.

Change-Id: I03578d07db00be01b610a8f5ce72e5521aea6a4b
---
 gdb/guile/scm-breakpoint.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/gdb/guile/scm-breakpoint.c b/gdb/guile/scm-breakpoint.c
index 0069d3371ff..d6c89aa8c71 100644
--- a/gdb/guile/scm-breakpoint.c
+++ b/gdb/guile/scm-breakpoint.c
@@ -353,8 +353,8 @@ gdbscm_make_breakpoint (SCM location_scm, SCM rest)
   char *location;
   int type_arg_pos = -1, access_type_arg_pos = -1,
       internal_arg_pos = -1, temporary_arg_pos = -1;
-  enum bptype type = bp_breakpoint;
-  enum target_hw_bp_type access_type = hw_write;
+  int type = bp_breakpoint;
+  int access_type = hw_write;
   int internal = 0;
   int temporary = 0;
   SCM result;
@@ -403,7 +403,7 @@ gdbscm_make_breakpoint (SCM location_scm, SCM rest)
     case bp_access_watchpoint:
     case bp_catchpoint:
       {
-	const char *type_name = bpscm_type_to_string (type);
+	const char *type_name = bpscm_type_to_string ((enum bptype) type);
 	gdbscm_misc_error (FUNC_NAME, type_arg_pos,
 			   gdbscm_scm_from_c_string (type_name),
 			   _("unsupported breakpoint type"));
@@ -417,8 +417,8 @@ gdbscm_make_breakpoint (SCM location_scm, SCM rest)
 
   bp_smob->is_scheme_bkpt = 1;
   bp_smob->spec.location = location;
-  bp_smob->spec.type = type;
-  bp_smob->spec.access_type = access_type;
+  bp_smob->spec.type = (enum bptype) type;
+  bp_smob->spec.access_type = (enum target_hw_bp_type) access_type;
   bp_smob->spec.is_internal = internal;
   bp_smob->spec.is_temporary = temporary;
 
-- 
2.26.2