The macro SafeStringValue() became just StringValue() in c5c05460ac,
and it is deprecated nowadays.
This patch replaces remaining macro usage. Some occurrences are left in
ext/stringio and ext/win32ole, they should be fixed upstream.
The macro itself is not deleted, because it may be used in extensions.
[Bug #20145]
Before this commit, both copy_compare_by_id and hash_copy will create a
copy of the ST table, so the ST table created in copy_compare_by_id will
be leaked.
h = { 1 => 2 }.compare_by_identity
10.times do
1_000_000.times do
h.select { false }
end
puts `ps -o rss= -p #{$$}`
end
Before:
110736
204352
300272
395520
460704
476736
542000
604704
682624
770528
After:
15504
16048
16144
16256
16320
16320
16752
16752
16752
16752
If a Hash is non-empty, there's no point calling `ar_force_convert_table`. We'll be immediately discarding that new st table, and replacing it with the new `identtable` st table that we're stealing out of `tmp`.
For non-empty Hashes, this function needs to rehash all the stored values (using the new `compare` and `hash` functions from `identhash`). It does so by writing into a newly allocated `tmp` Hash, and then transferring ownership of its st table into `self`.
For empty Hashes, we can skip allocating this `tmp`, because there's nothing to re-hash. We can just modify our new st table's `type` in-place.
* delete `ar_try_convert` but use `ar_force_convert_table`
to make program simple.
* `ar_force_convert_table` checks hash modification while
calling `#hash` method with the following strategy:
1. copy keys (and vals) of ar_table
2. calc hashes from keys
3. check copied keys and hash's keys. if not matched, repeat from 1
fix [Bug #20050]
st.c redefines malloc and free to be ruby_xmalloc and ruby_xfree, so
when this was copied into hash.c it ended up mismatching an xmalloc with
a regular free, which ended up inflating oldmalloc_increase_bytes when
hashes were freed by minor GC.
ar_table may be converted to st_table by `ar_force_convert_table`.
If the conversion occurs during the iteration of ar_table, the iteration
may lead to memory corruption.
This change prevents the catastrophy by throwing an exception when the
conversion is detected.
This issue is reported by [SuperS](https://hackerone.com/superss)
According to the C99 specification section 7.20.3.2 paragraph 2:
> If ptr is a null pointer, no action occurs.
So we do not need to check that the pointer is a null pointer.
st_copy allocates a st_table, which is not needed for hashes since it is
allocated by VWA and embedded, so this causes a memory leak.
The following script demonstrates the issue:
```ruby
20.times do
100_000.times do
{a: 1, b: 2, c: 3, d: 4, e: 5, f: 6, g: 7, h: 8, i: 9}
end
puts `ps -o rss= -p #{$$}`
end
```
