merge revision(s) 28678997e40869f5591eae60edd9757334426ffb,8797f48373dcfa3ff8e748667732dea8aea4347e: [Backport #15937]

	Preserve the string content at self-copying
	
	* string.c (rb_str_init): preserve the embedded content when
	  self-copying with a capacity.  [Bug #15937]
	
	New buffer for shared string
	
	* string.c (rb_str_init): allocate new buffer if the string is
	  shared.  [Bug #15937]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_5@67769 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 28 insertions, 2 deletions

diff --git a/string.c b/string.c
index 9a81cefa72..5f8bd363fc 100644
--- a/string.c
+++ b/string.c
@@ -1297,6 +1297,7 @@ str_new_empty(VALUE str)
 }
 
 #define STR_BUF_MIN_SIZE 127
+STATIC_ASSERT(STR_BUF_MIN_SIZE, STR_BUF_MIN_SIZE > RSTRING_EMBED_LEN_MAX);
 
 VALUE
 rb_str_buf_new(long capa)
@@ -1579,7 +1580,18 @@ rb_str_init(int argc, VALUE *argv, VALUE str)
 	    }
 	    str_modifiable(str);
 	    if (STR_EMBED_P(str)) { /* make noembed always */
-		RSTRING(str)->as.heap.ptr = ALLOC_N(char, (size_t)capa + termlen);
+                char *new_ptr = ALLOC_N(char, (size_t)capa + termlen);
+                memcpy(new_ptr, RSTRING(str)->as.ary, RSTRING_EMBED_LEN_MAX + 1);
+                RSTRING(str)->as.heap.ptr = new_ptr;
+            }
+            else if (FL_TEST(str, STR_SHARED|STR_NOFREE)) {
+                const size_t size = (size_t)capa + termlen;
+                const char *const old_ptr = RSTRING_PTR(str);
+                const size_t osize = RSTRING(str)->as.heap.len + TERM_LEN(str);
+                char *new_ptr = ALLOC_N(char, (size_t)capa + termlen);
+                memcpy(new_ptr, old_ptr, osize < size ? osize : size);
+                FL_UNSET_RAW(str, STR_SHARED);
+                RSTRING(str)->as.heap.ptr = new_ptr;
 	    }
 	    else if (STR_HEAP_SIZE(str) != (size_t)capa + termlen) {
 		REALLOC_N(RSTRING(str)->as.heap.ptr, char, (size_t)capa + termlen);
diff --git a/test/ruby/test_string.rb b/test/ruby/test_string.rb
index ae5b22c19e..2aed90193e 100644
--- a/test/ruby/test_string.rb
+++ b/test/ruby/test_string.rb
@@ -68,6 +68,20 @@ class TestString < Test::Unit::TestCase
     assert_raise(FrozenError){ str.__send__(:initialize, encoding: 'euc-jp') }
     assert_raise(FrozenError){ str.__send__(:initialize, 'abc', encoding: 'euc-jp') }
     assert_raise(FrozenError){ str.__send__(:initialize, 'abc', capacity: 1000, encoding: 'euc-jp') }
+
+    str = S("")
+    assert_equal("mystring", str.__send__(:initialize, "mystring"))
+    str = S("mystring")
+    assert_equal("mystring", str.__send__(:initialize, str))
+    str = S("")
+    assert_equal("mystring", str.__send__(:initialize, "mystring", capacity: 1000))
+    str = S("mystring")
+    assert_equal("mystring", str.__send__(:initialize, str, capacity: 1000))
+  end
+
+  def test_initialize_shared
+    String.new(str = "mystring" * 10).__send__(:initialize, capacity: str.bytesize)
+    assert_equal("mystring", str[0, 8])
   end
 
   def test_initialize_nonstring
diff --git a/version.h b/version.h
index 818dea40de..62221f0ddf 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.5.6"
 #define RUBY_RELEASE_DATE "2019-08-27"
-#define RUBY_PATCHLEVEL 187
+#define RUBY_PATCHLEVEL 188
 
 #define RUBY_RELEASE_YEAR 2019
 #define RUBY_RELEASE_MONTH 8