Add specs for correct null termination with encoding min length \0 bytes

Author: eregon

spec/ruby/optional/capi/ext/string_spec.c

@@ -437,6 +437,12 @@ VALUE string_spec_RSTRING_PTR_read(VALUE self, VALUE str, VALUE path) {
   return capacities;
 }
 
+VALUE string_spec_RSTRING_PTR_null_terminate(VALUE self, VALUE str, VALUE min_length) {
+  char* ptr = RSTRING_PTR(str);
+  char* end = ptr + RSTRING_LEN(str);
+  return rb_str_new(end, FIX2LONG(min_length));
+}
+
 VALUE string_spec_StringValue(VALUE self, VALUE str) {
   return StringValue(str);
 }
@@ -662,6 +668,7 @@ void Init_string_spec(void) {
   rb_define_method(cls, "RSTRING_PTR_after_funcall", string_spec_RSTRING_PTR_after_funcall, 2);
   rb_define_method(cls, "RSTRING_PTR_after_yield", string_spec_RSTRING_PTR_after_yield, 1);
   rb_define_method(cls, "RSTRING_PTR_read", string_spec_RSTRING_PTR_read, 2);
+  rb_define_method(cls, "RSTRING_PTR_null_terminate", string_spec_RSTRING_PTR_null_terminate, 2);
   rb_define_method(cls, "StringValue", string_spec_StringValue, 1);
   rb_define_method(cls, "SafeStringValue", string_spec_SafeStringValue, 1);
   rb_define_method(cls, "rb_str_hash", string_spec_rb_str_hash, 1);

spec/ruby/optional/capi/string_spec.rb

@@ -97,6 +97,32 @@ def inspect
     end
   end
 
+  describe "rb_str_set_len on a UTF-16 String" do
+    before :each do
+      @str = "abcdefghij".force_encoding(Encoding::UTF_16BE)
+      # Make sure to unshare the string
+      @s.rb_str_modify(@str)
+    end
+
+    it "inserts two NULL bytes at the length" do
+      @s.rb_str_set_len(@str, 4).b.should == "abcd".b
+      @s.rb_str_set_len(@str, 8).b.should == "abcd\x00\x00gh".b
+    end
+  end
+
+  describe "rb_str_set_len on a UTF-32 String" do
+    before :each do
+      @str = "abcdefghijkl".force_encoding(Encoding::UTF_32BE)
+      # Make sure to unshare the string
+      @s.rb_str_modify(@str)
+    end
+
+    it "inserts four NULL bytes at the length" do
+      @s.rb_str_set_len(@str, 4).b.should == "abcd".b
+      @s.rb_str_set_len(@str, 12).b.should == "abcd\x00\x00\x00\x00ijkl".b
+    end
+  end
+
   describe "rb_str_buf_new" do
     it "returns the equivalent of an empty string" do
       buf = @s.rb_str_buf_new(10, nil)
@@ -592,6 +618,12 @@ def inspect
       capacities[0].should < capacities[1]
       str.should == "fixture file contents to test read() with RSTRING_PTR"
     end
+
+    it "terminates the string with at least (encoding min length) \\0 bytes" do
+      @s.RSTRING_PTR_null_terminate("abc", 1).should == "\x00"
+      @s.RSTRING_PTR_null_terminate("abc".encode("UTF-16BE"), 2).should == "\x00\x00"
+      @s.RSTRING_PTR_null_terminate("abc".encode("UTF-32BE"), 4).should == "\x00\x00\x00\x00"
+    end
   end
 
   describe "RSTRING_LEN" do