fix: decompress with streaming compress binary

Author: SpringMT

ext/zstdruby/zstdruby.c

@@ -87,24 +87,24 @@ static VALUE rb_compress_using_dict(int argc, VALUE *argv, VALUE self)
 
 static VALUE decompress_buffered(ZSTD_DCtx* dctx, const char* input_data, size_t input_size)
 {
-  VALUE output_string = rb_str_new(NULL, 0);
-  ZSTD_outBuffer output = { NULL, 0, 0 };
-
   ZSTD_inBuffer input = { input_data, input_size, 0 };
+  VALUE result = rb_str_new(0, 0);
+
   while (input.pos < input.size) {
+    ZSTD_outBuffer output = { NULL, 0, 0 };
     output.size += ZSTD_DStreamOutSize();
-    rb_str_resize(output_string, output.size);
+    VALUE output_string = rb_str_new(NULL, output.size);
     output.dst = RSTRING_PTR(output_string);
 
     size_t ret = zstd_stream_decompress(dctx, &output, &input, false);
     if (ZSTD_isError(ret)) {
       ZSTD_freeDCtx(dctx);
       rb_raise(rb_eRuntimeError, "%s: %s", "ZSTD_decompressStream failed", ZSTD_getErrorName(ret));
     }
+    rb_str_cat(result, output.dst, output.pos);
   }
-  rb_str_resize(output_string, output.pos);
   ZSTD_freeDCtx(dctx);
-  return output_string;
+  return result;
 }
 
 static VALUE rb_decompress(int argc, VALUE *argv, VALUE self)
@@ -134,7 +134,7 @@ static VALUE rb_decompress(int argc, VALUE *argv, VALUE self)
   VALUE output = rb_str_new(NULL, uncompressed_size);
   char* output_data = RSTRING_PTR(output);
 
-  size_t const decompress_size =  zstd_decompress(dctx, output_data, uncompressed_size, input_data, input_size, false);
+  size_t const decompress_size = zstd_decompress(dctx, output_data, uncompressed_size, input_data, input_size, false);
   if (ZSTD_isError(decompress_size)) {
     rb_raise(rb_eRuntimeError, "%s: %s", "decompress error", ZSTD_getErrorName(decompress_size));
   }

spec/zstd-ruby_spec.rb

@@ -87,6 +87,14 @@ def to_str
       expect(decompressed.force_encoding('UTF-8')).to eq('あああ')
     end
 
+    it 'should work hash equal streaming compress' do
+      simple_compressed = Zstd.compress('あ')
+      stream = Zstd::StreamingCompress.new
+      stream << "あ"
+      streaming_compressed = stream.finish
+      expect(Zstd.decompress(simple_compressed).force_encoding('UTF-8').hash).to eq(Zstd.decompress(streaming_compressed).force_encoding('UTF-8').hash)
+    end
+
     it 'should raise exception with unsupported object' do
       expect { Zstd.decompress(Object.new) }.to raise_error(TypeError)
     end
@@ -111,4 +119,3 @@ def to_str
     end
   end
 end
-