[PATCH 07/13] format-check: add a function to check to type of 'n' arguments

[Luc Van Oostenryck <luc.vanoostenryck@gmail.com>]

This checking is currently done by check_assignment_types()
but this is not adequate, for example because it allows
a void pointer while a pointer of the specific type is needed.

So, add a custom checking function.

Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
---
 verify-format.c | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/verify-format.c b/verify-format.c
index 90fe0ede0431..1b40b2c796a2 100644
--- a/verify-format.c
+++ b/verify-format.c
@@ -146,6 +146,41 @@ static int printf_fmt_string(struct format_type *fmt,
 	return !(*typediff = check_printf_string(fmt, ctype));
 }
 
+
+#define MOD_IGN (MOD_QUALIFIER | MOD_FUN_ATTR)
+static inline const char *compare_pointer(struct symbol *target, struct symbol *source)
+{
+	unsigned long modt = target->ctype.modifiers & MOD_IGN & ~MOD_REV_QUAL;
+	unsigned long mods = source->ctype.modifiers & MOD_IGN &  MOD_REV_QUAL;
+
+	return type_difference(&target->ctype, &source->ctype, mods, modt);
+}
+
+// For 'n' specifier
+static const char *check_printf_length(struct format_type *fmt, struct symbol *source)
+{
+	const char *typediff = "different base types";
+	struct symbol *target = fmt->type;
+
+	examine_pointer_target(target);
+	examine_pointer_target(source);
+
+	if (type_class(source, &source) != CLASS_PTR)
+		return typediff;
+	if (source->ctype.as)
+		return "different address spaces";
+
+	return compare_pointer(target, source);
+}
+
+static int printf_fmt_length(struct format_type *fmt,
+			      struct expression **expr,
+			      struct symbol *ctype,
+			      const char **typediff)
+{
+	return !(*typediff = check_printf_length(fmt, ctype));
+}
+
 static int printf_fmt_pointer(struct format_type *fmt,
 			      struct expression **expr,
 			      struct symbol *ctype,
@@ -335,7 +370,7 @@ static struct format_type *parse_printf_get_fmt(struct format_type *type,
 		/* pointer to an de-referenced int/etc */
 		// todo - we should construct pointer to int/etc //
 		// also should not have any flags or widths for this
-		type->test = printf_fmt_pointer;
+		type->test = printf_fmt_length;
 		type->type = &const_ptr_ctype;
 		break;
 	default:
-- 
2.28.0