Ruby

[ruby/psych] Guard from memory leak in Psych::Emitter#start_document

When an exception is raised, it can leak memory in head. There are two
places that can leak memory:

1. Check_Type(tuple, T_ARRAY) can leak memory if tuple is not an
   array.
2. StringValue(name) and StringValue(value) if they are not strings
   and the call to to_str does not return a string.

This commit fixes these memory leaks by wrapping the code around a
rb_ensure so that the memory is freed in all cases.

The following code demonstrates the memory leak:

emitter = Psych::Emitter.new(StringIO.new) nil_to_string_tags = [[nil, "tag:TALOS"]] + ([1] * 1000) expected_array_tags = [1] * 1000 10.times do 1_000.times do # Raises `no implicit conversion of nil into String` emitter.start_document([], nil_to_string_tags, 0) rescue TypeError end 1_000.times do # Raises `wrong argument type Integer (expected Array)` emitter.start_document([], expected_array_tags, 0) rescue TypeError end puts `ps -o rss= -p #{$$}` end 

Before:

47248 79728 111968 144224 176480 208896 241104 273280 305472 337664 

After:

14832 15088 15344 15344 15360 15632 15632 15632 15648 15648 

https://github.com/ruby/psych/commit/053af73818