dwarves: Introduce function__prototype

Basically a wrapper for ftype__fprintf(&function__proto, ...) for the
cases we want the prototype rendered to a buffer, not to a file.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

dwarves.c

@@ -1479,6 +1479,20 @@ const char *function__name(struct function *self, const struct cu *cu)
 	return self->name;
 }
 
+const char *function__prototype(const struct function *self,
+				const struct cu *cu, char *bf, size_t len) 
+{
+	FILE *bfp = fmemopen(bf, len, "w");
+
+	if (bfp != NULL) {
+		ftype__fprintf(&self->proto, cu, NULL, 0, 0, 0, bfp);
+		fclose(bfp);
+	} else
+		snprintf(bf, len, "<ERROR(%s): fmemopen failed!>", __func__);
+
+	return bf;
+}
+
 int ftype__has_parm_of_type(const struct ftype *self, const struct tag *target,
 			    const struct cu *cu)
 {

dwarves.h

@@ -382,6 +382,11 @@ static inline struct function *tag__function(const struct tag *self)
 	return (struct function *)self;
 }
 
+static inline struct tag *function__tag(const struct function *self)
+{
+	return (struct tag *)self;
+}
+
 /** 
  * function__for_each_parameter - iterate thru all the parameters
  * @self: struct function instance to iterate
@@ -490,6 +495,9 @@ extern const char *function__name(struct function *self, const struct cu *cu);
 extern size_t function__fprintf_stats(const struct tag *tag_self,
 				      const struct cu *cu,
 				      FILE *fp);
+extern const char *function__prototype(const struct function *self,
+				       const struct cu *cu,
+				       char *bf, size_t len);
 
 void lexblock__add_inline_expansion(struct lexblock *self,
 				    struct inline_expansion *exp);