hash: keep fstrings of tainted strings for string keys

The same hash keys may be loaded from tainted data sources
frequently (e.g. parsing headers from socket or loading
YAML data from a file).  If a non-tainted fstring already
exists (because the application expects the hash key),
cache and deduplicate the tainted version in the new
tainted_frozen_strings table.

For non-embedded strings, this also allows sharing with the
underlying malloc-ed data.

* vm_core.h (rb_vm_struct): add tainted_frozen_strings
* vm.c (ruby_vm_destruct): free tainted_frozen_strings
  (Init_vm_objects): initialize tainted_frozen_strings
  (rb_vm_tfstring_table): accessor for tainted_frozen_strings
* internal.h: declare rb_fstring_existing, rb_vm_tfstring_table
* hash.c (fstring_existing_str): remove (moved to string.c)
  (hash_aset_str): use rb_fstring_existing
* string.c (rb_fstring_existing): new, based on fstring_existing_str
  (tainted_fstr_update): new
  (rb_fstring_existing0): new, based on fstring_existing_str
  (rb_tainted_fstring_existing): new, special case for tainted strings
  (rb_str_free): delete from tainted_frozen_strings table
* test/ruby/test_optimization.rb (test_hash_reuse_fstring): new test
  [ruby-core:82012] [Bug #13737]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@59354 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 2 insertions, 1 deletions

diff --git a/internal.h b/internal.h
index 81f4d2b91d..e6d50ebcda 100644
--- a/internal.h
+++ b/internal.h
@@ -1574,6 +1574,7 @@ VALUE rb_strftime(const char *format, size_t format_len, rb_encoding *enc,
 /* string.c */
 VALUE rb_fstring(VALUE);
 VALUE rb_fstring_new(const char *ptr, long len);
+VALUE rb_fstring_existing(VALUE);
 #define rb_fstring_lit(str) rb_fstring_new((str), rb_strlen_lit(str))
 #define rb_fstring_literal(str) rb_fstring_lit(str)
 VALUE rb_fstring_cstr(const char *str);
@@ -1726,7 +1727,7 @@ void rb_vm_check_redefinition_by_prepend(VALUE klass);
 VALUE rb_yield_refine_block(VALUE refinement, VALUE refinements);
 VALUE ruby_vm_special_exception_copy(VALUE);
 PUREFUNC(st_table *rb_vm_fstring_table(void));
-
+PUREFUNC(st_table *rb_vm_tfstring_table(void));
 
 /* vm_dump.c */
 void rb_print_backtrace(void);