diff options
| author | Peter Zhu <[email protected]> | 2023-11-30 14:47:09 -0500 |
|---|---|---|
| committer | Peter Zhu <[email protected]> | 2023-12-01 15:04:31 -0500 |
| commit | 80ea7fbad871b2222b16af1bd9f39e1f1828bbd4 (patch) | |
| tree | a2cb0155f9ad11b4a8f852efffffa20390e6060c | |
| parent | 0ed55bf09713299201caec3ba9d9ef7ba6e8526f (diff) | |
Pin embedded shared strings
Embedded shared strings cannot be moved because strings point into the
slot of the shared string. There may be code using the RSTRING_PTR on
the stack, which would pin the string but not pin the shared string,
causing it to move.
| -rw-r--r-- | gc.c | 12 | ||||
| -rw-r--r-- | internal/string.h | 1 | ||||
| -rw-r--r-- | string.c | 20 |
3 files changed, 10 insertions, 23 deletions
@@ -7346,7 +7346,16 @@ gc_mark_children(rb_objspace_t *objspace, VALUE obj) case T_STRING: if (STR_SHARED_P(obj)) { - gc_mark(objspace, any->as.string.as.heap.aux.shared); + if (STR_EMBED_P(any->as.string.as.heap.aux.shared)) { + /* Embedded shared strings cannot be moved because this string + * points into the slot of the shared string. There may be code + * using the RSTRING_PTR on the stack, which would pin this + * string but not pin the shared string, causing it to move. */ + gc_mark_and_pin(objspace, any->as.string.as.heap.aux.shared); + } + else { + gc_mark(objspace, any->as.string.as.heap.aux.shared); + } } break; @@ -10701,7 +10710,6 @@ gc_update_object_references(rb_objspace_t *objspace, VALUE obj) VALUE old_root = any->as.string.as.heap.aux.shared; UPDATE_IF_MOVED(objspace, any->as.string.as.heap.aux.shared); VALUE new_root = any->as.string.as.heap.aux.shared; - rb_str_update_shared_ary(obj, old_root, new_root); } /* If, after move the string is not embedded, and can fit in the diff --git a/internal/string.h b/internal/string.h index abb0a536ad..8c481f979e 100644 --- a/internal/string.h +++ b/internal/string.h @@ -64,7 +64,6 @@ VALUE rb_str_upto_endless_each(VALUE, int (*each)(VALUE, VALUE), VALUE); void rb_str_make_embedded(VALUE); size_t rb_str_size_as_embedded(VALUE); bool rb_str_reembeddable_p(VALUE); -void rb_str_update_shared_ary(VALUE str, VALUE old_root, VALUE new_root); RUBY_SYMBOL_EXPORT_END VALUE rb_fstring_new(const char *ptr, long len); @@ -280,26 +280,6 @@ rb_str_make_embedded(VALUE str) } void -rb_str_update_shared_ary(VALUE str, VALUE old_root, VALUE new_root) -{ - // if the root location hasn't changed, we don't need to update - if (new_root == old_root) { - return; - } - - // if the root string isn't embedded, we don't need to touch the pointer. - // it already points to the shame shared buffer - if (!STR_EMBED_P(new_root)) { - return; - } - - size_t offset = (size_t)((uintptr_t)RSTRING(str)->as.heap.ptr - (uintptr_t)RSTRING(old_root)->as.embed.ary); - - RUBY_ASSERT(RSTRING(str)->as.heap.ptr >= RSTRING(old_root)->as.embed.ary); - RSTRING(str)->as.heap.ptr = RSTRING(new_root)->as.embed.ary + offset; -} - -void rb_debug_rstring_null_ptr(const char *func) { fprintf(stderr, "%s is returning NULL!! " |