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	Add test cases of rb_arithmetic_sequence_extract	2018-12-12 21:17:04 +00:00
array
bignum
bug_reporter	test_bug_reporter.rb: make it work with --jit	2018-04-28 09:02:56 +00:00
class
debug	* remove trailing spaces.	2018-09-21 06:41:09 +00:00
exception
file
float
funcall
gvl	introduce rb_nogvl C-API to mark ubf as async-signal-safe	2019-01-04 13:14:11 +00:00
hash
integer	numeric.c: fix infinite loop	2019-03-11 01:37:16 +00:00
iseq_load	test_iseq_load.rb: increase timeout for stressful roundtrip	2018-12-29 01:53:10 +00:00
iter
load
marshal
method
num2int
path_to_class
popen_deadlock
postponed_job
proc
rational
st
string	str_duplicate: Don't share with a frozen shared string	2019-05-09 10:04:19 +09:00
struct
symbol	Symbol creation is not a problem now unless pinned down	2019-03-06 11:49:53 +00:00
thread_fd_close	revert revert of r65285	2018-10-21 23:20:32 +00:00
time
tracepoint
typeddata
vm
wait_for_single_fd	test_wait_for_single_fd.rb: remove with_pipe helper	2018-05-14 23:51:39 +00:00
win32
test_bug-3571.rb
test_bug-5832.rb
test_notimplement.rb	Add more assertions for NotImplementedError of instance method	2018-08-21 14:57:56 +00:00
test_printf.rb
test_recursion.rb
test_scan_args.rb	The combination of non-Symbol keys and Symbol keys is now allowed again	2019-03-11 12:48:33 +00:00