This time, the allocated memory comes from the string object, which is
referenced from GC arena. The memory region will be reclaimed when the C
function called from VM is terminated, or the GC arena is restored.
When I found this function, I expected it to behave the same as the
`alloca(3)` function, but it is accually the `mrb_alloca()` function
does not free the heap until the `mrb_close()` function is called.
Also, even if it is deleted, it can be replaced with the combination
of the `MRB_TT_DATA` object and the `mrb_gv_set()` function if it is
sure necessary.
Functions to add prototypes to headers:
* mrb_ary_splice()
* mrb_notimplement()
* mrb_vformat()
* mrb_cstr_to_dbl()
* mrb_cstr_to_inum()
Functions to be made `static` (`MRB_API` was not needed):
* mrb_mod_module_function()
* mrb_obj_hash()
* mrb_str_len_to_inum()
Functions to remove `MRB_API` from definitions (referenced from within `libmruby`):
* mrb_mod_cv_defined()
* mrb_mod_cv_get()
* mrb_f_send()
Small symbols with all alphanumeric characters (<5) are packed in 32bit
symbol integer a la base64. This means those small symbols are not
listed in `Symbol.all_symbols`.
In 4174e02, we removed the symbol hash table from `mrb_state` but
`find_symbol` was too slow with linear search. My performance estimation
was wrong. So we implemented a new compact hash table for symbols.
Use linear search instead. Number of symbols is usually small (<1K), so
we don't need performance boost from hash tables. In our benchmark
measurement, hash tables consumes 790KB for `build/full-debug/mrbtest`.
We have added internal convenience method `__to_str` which
does string type check.
The issue #3854 was fixed but fundamental flaw of lack of stack
depth check along with fibers still remains. Use `MRB_GC_FIXED_ARENA`
for workaround.
The ISO standard does not include implicit type conversion using
`to_int`. This implicit conversion often causes vulnerability.
There will be no more attacks like #4120.
In addition, we have added internal convenience method `__to_int` which
does type check and conversion (from floats).
Now the method tables (in classes/modules and caches) keeps C function
pointers without wrapping in `struct RProc` objects. For the sake of
portability, `mrb_method_t` is represented by the struct and union, but
if the most significant bit of the pointer is not used by the platform,
`mrb_method_t` should be packed in `uintptr_t` to reduce memory usage.
`MRB_METHOD_TABLE_INLINE` is turned on by default for linux.
Yukihiro "Matz" Matsumoto