Get rid of indirect sharing
* string.c (str_duplicate): share the root shared string if the
original string is already sharing, so that all shared strings
refer the root shared string directly. indirect sharing can
cause a dangling pointer.
[Bug #15792]
str_duplicate: Don't share with a frozen shared string
This is a follow up for 3f9562015e.
Before this commit, it was possible to create a shared string which
shares with another shared string by passing a frozen shared string
to `str_duplicate`.
Such string looks like:
```
-------- -----------------
| root | ------ owns -----> | root's buffer |
-------- -----------------
^ ^ ^
----------- | |
| shared1 | ------ references ----- |
----------- |
^ |
----------- |
| shared2 | ------ references ---------
-----------
```
This is bad news because `rb_fstring(shared2)` can make `shared1`
independent, which severs the reference from `shared1` to `root`:
```c
/* from fstr_update_callback() */
str = str_new_frozen(rb_cString, shared2); /* can return shared1 */
if (STR_SHARED_P(str)) { /* shared1 is also a shared string */
str_make_independent(str); /* no frozen check */
}
```
If `shared1` was the only reference to `root`, then `root` can be
reclaimed by the GC, leaving `shared2` in a corrupted state:
```
----------- --------------------
| shared1 | -------- owns --------> | shared1's buffer |
----------- --------------------
^
|
----------- -------------------------
| shared2 | ------ references ----> | root's buffer (freed) |
----------- -------------------------
```
Here is a reproduction script for the situation this commit fixes.
```ruby
a = ('a' * 24).strip.freeze.strip
-a
p a
4.times { GC.start }
p a
```
- string.c (str_duplicate): always share with the root string when
the original is a shared string.
- test_rb_str_dup.rb: specifically test `rb_str_dup` to make
sure it does not try to share with a shared string.
[Bug #15792]
Closes: https://github.com/ruby/ruby/pull/2159
Update dependencies
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_6@67731 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Onigumo 6 (r57045) introduced new onigumo.h header file, which is
required from quite much everywhere. This commit adds necessary
dependencies.
Note: ruby/oniguruma.h now includes onigumo.h,
ruby/io.h includes oniguruma.h,
ruby/encoding.h also includes oniguruma.h,
and internal.h includes encoding.h.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58054 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* ext/-test-/{bignum,debug,exception,string}/depend: TEST_INIT_FUNCS
is created by globbing in extconf.rb
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42502 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
HFS Plus (Mac OS Extended) uses a variant of Normal Form D in which
U+2000 through U+2FFF, U+F900 through U+FAFF, and U+2F800 through
U+2FAFF are not decomposed (this avoids problems with round trip
conversions from old Mac text encodings).
http://developer.apple.com/library/mac/qa/qa1173/_index.html
Therefore fix r42457 to exclude the range.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42498 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
