Avoid keeping pointers from `mrb_sym2name_len()`; fix #4342

The addresses for packed inline symbols reference `mrb->symbuf` that
could be overridden by the later call of `mrb_sym2name_len`. Since
file names in call stack information are kept as symbols, keeping the
address in the C structures could cause problems like #4342.

This changes small incompatible changes in function prototypes:
* `mrb_parser_get_filename`: return value changed to `mrb_sym`.
* `mrb_debug_get_filename`: add `mrb_state*` as a first argument.
* `mrb_debug_get_line`: ditto.

I believe above functions are almost internal, and no third-party
mrbgem use them.

1 files changed, 8 insertions, 1 deletions

diff --git a/src/symbol.c b/src/symbol.c
index 8ca03344c..96ca9dd17 100644
--- a/src/symbol.c
+++ b/src/symbol.c
@@ -520,7 +520,14 @@ mrb_sym2name(mrb_state *mrb, mrb_sym sym)
     return name;
   }
   else {
-    mrb_value str = mrb_str_dump(mrb, mrb_str_new_static(mrb, name, len));
+    mrb_value str;
+    if (sym&1) {                /* inline symbol */
+      str = mrb_str_new(mrb, name, len);
+    }
+    else {
+      str = mrb_str_new_static(mrb, name, len);
+    }
+    str = mrb_str_dump(mrb, str);
     return RSTRING_PTR(str);
   }
 }