Alan Wu c06ddfee87 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		2019-05-09 10:04:19 +09:00
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arith_seq/extract	../arith_seq/../extract.c: remove unused variable	2018-12-21 16:19:31 +00:00
array/resize
bignum	Use $(hdrdir) for include/ruby.h, as well as r67033	2019-02-11 13:43:14 +00:00
bug-3571
bug-5832
bug_reporter
class	Use $(hdrdir) for include/ruby.h, as well as r67033	2019-02-11 13:43:14 +00:00
debug	Use $(hdrdir) for include/ruby.h, as well as r67033	2019-02-11 13:43:14 +00:00
dln/empty
exception	Use $(hdrdir) for include/ruby.h, as well as r67033	2019-02-11 13:43:14 +00:00
fatal
file	Use $(hdrdir) for include/ruby.h, as well as r67033	2019-02-11 13:43:14 +00:00
float
funcall	ruby.h: relax rb_funcall check on extra args for clang	2018-01-30 23:55:49 +00:00
gvl/call_without_gvl	Suppress a warning	2019-02-13 15:20:50 +00:00
hash
integer	numeric.c: fix infinite loop	2019-03-11 01:37:16 +00:00
iseq_load
iter	UNREACHABLE_RETURN	2018-07-24 05:38:07 +00:00
load
marshal
memory_status
method
notimplement	Add more assertions for NotImplementedError of instance method	2018-08-21 14:57:56 +00:00
num2int
path_to_class
popen_deadlock
postponed_job
printf
proc
rational	Use $(hdrdir) for include/ruby.h, as well as r67033	2019-02-11 13:43:14 +00:00
recursion
regexp
scan_args
st
string	str_duplicate: Don't share with a frozen shared string	2019-05-09 10:04:19 +09:00
struct	Use $(hdrdir) for include/ruby.h, as well as r67033	2019-02-11 13:43:14 +00:00
symbol
thread_fd_close
time	Use $(hdrdir) for include/ruby.h, as well as r67033	2019-02-11 13:43:14 +00:00
tracepoint
typeddata
vm
wait_for_single_fd	-test-/wait_for_single_fd: fix -Wformat-security warning	2018-05-15 01:29:14 +00:00
win32	test_console_attr.rb: fix test	2018-01-15 12:25:24 +00:00
auto_ext.rb