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Fix thread safety of strio_free #223

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Merged
kou merged 1 commit into from
Aug 1, 2026
+17 −8
Merged

Fix thread safety of strio_free #223

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25 changes: 17 additions & 8 deletions ext/stringio/stringio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,19 @@ STRINGIO_VERSION = "3.2.1";
# define RB_INTEGER_TYPE_P(c) (FIXNUM_P(c) || RB_TYPE_P(c, T_BIGNUM))
#endif

/* strio_free may run on any thread, so the refcount shared by #initialize_copy must be atomic */
#ifdef RUBY_TYPED_THREAD_SAFE_FREE
# include "ruby/atomic.h"
typedef rb_atomic_t strio_refcnt_t;
# define STRIO_REFCNT_INC(ptr) RUBY_ATOMIC_INC((ptr)->count)
# define STRIO_REFCNT_DEC(ptr) (RUBY_ATOMIC_FETCH_SUB((ptr)->count, 1) == 1)
#else
# define RUBY_TYPED_THREAD_SAFE_FREE RUBY_TYPED_FREE_IMMEDIATELY
typedef int strio_refcnt_t;
# define STRIO_REFCNT_INC(ptr) ((void)++(ptr)->count)
# define STRIO_REFCNT_DEC(ptr) (--(ptr)->count <= 0)
#endif

#ifndef RB_PASS_CALLED_KEYWORDS
# define rb_funcallv_kw(recv, mid, arg, argv, kw_splat) rb_funcallv(recv, mid, arg, argv)
# define rb_class_new_instance_kw(argc, argv, klass, kw_splat) rb_class_new_instance(argc, argv, klass)
Expand Down Expand Up @@ -63,7 +76,7 @@ struct StringIO {
long pos;
long lineno;
rb_io_mode_t flags;
int count;
strio_refcnt_t count;
};

static struct StringIO *get_strio_for_read(VALUE self);
Expand Down Expand Up @@ -105,8 +118,8 @@ static void
strio_free(void *p)
{
struct StringIO *ptr = p;
if (--ptr->count <= 0) {
xfree(ptr);
if (STRIO_REFCNT_DEC(ptr)) {
xfree(ptr);
}
}

Expand All @@ -116,10 +129,6 @@ strio_memsize(const void *p)
return sizeof(struct StringIO);
}

#ifndef RUBY_TYPED_THREAD_SAFE_FREE
#define RUBY_TYPED_THREAD_SAFE_FREE RUBY_TYPED_FREE_IMMEDIATELY
#endif

static const rb_data_type_t strio_data_type = {
"strio",
{
Expand Down Expand Up @@ -778,7 +787,7 @@ strio_copy(VALUE copy, VALUE orig)
RB_OBJ_WRITTEN(copy, old_string, ptr->string);
RB_FL_UNSET_RAW(copy, STRIO_READWRITE);
RB_FL_SET_RAW(copy, RB_FL_TEST_RAW(orig, STRIO_READWRITE));
++ptr->count;
STRIO_REFCNT_INC(ptr);
return copy;
}

Expand Down