fix: clear code-range when re-using a string buffer (jruby#9035)

kares · kares · commit 4df056f5e6ce · 2025-10-24T19:23:27.000+02:00
diff --git a/core/src/main/java/org/jruby/util/io/EncodingUtils.java b/core/src/main/java/org/jruby/util/io/EncodingUtils.java
@@ -1333,7 +1333,7 @@ public static RubyString setStrBuf(Ruby runtime, final IRubyObject obj, final in
             str = obj.convertToString();
             int clen = str.size();
             if (clen >= len) {
-                str.modify();
+                str.modifyAndClearCodeRange();
                 return str;
             }
             str.modifyExpand(len);
diff --git a/test/jruby/test_io.rb b/test/jruby/test_io.rb
@@ -173,6 +173,27 @@ def test_file_read_with_nil_buffer
      assert_equal " ", f.read(1, nil)
   end
 
+  def test_file_read_into_buffer_code_range
+    buf = String.new
+    buf.concat "¿Cómo estás? Ça va bien?"
+    assert_false buf.ascii_only? # base-line: scan and set the code-range for the buffer
+
+    require 'tempfile'
+    tmpfile = Tempfile.new('file')
+    tmpfile.open
+    tmpfile.write("ascii only")
+    tmpfile.flush
+    tmpfile.close
+
+    File.open(tmpfile.path, encoding: 'binary') do |file|
+      file.read(10, buf) # read less then buf.size
+    end
+    tmpfile.delete
+
+    assert_true buf.ascii_only? # reading into the buffer should have cleared the code-range
+    assert_equal 'ascii only', buf
+  end
+
   def test_open
     ensure_files @file
 

Original file line number	Diff line number	Diff line change
`@@ -1333,7 +1333,7 @@ public static RubyString setStrBuf(Ruby runtime, final IRubyObject obj, final in`
`1333`	`1333`	`str = obj.convertToString();`
`1334`	`1334`	`int clen = str.size();`
`1335`	`1335`	`if (clen >= len) {`
`1336`		`- str.modify();`
	`1336`	`+ str.modifyAndClearCodeRange();`
`1337`	`1337`	`return str;`
`1338`	`1338`	`}`
`1339`	`1339`	`str.modifyExpand(len);`