[properties] support encoding detection of large property files IDEA-360552

GitOrigin-RevId: 4b8e53f97bc93df6c9b2b212b5fa3b92692773c1

java/compiler/tests/com/intellij/compiler/CompilerEncodingServiceTest.java

@@ -2,6 +2,7 @@
 package com.intellij.compiler;
 
 import com.intellij.openapi.application.WriteAction;
+import com.intellij.openapi.fileEditor.impl.LoadTextUtil;
 import com.intellij.openapi.util.Ref;
 import com.intellij.openapi.util.registry.Registry;
 import com.intellij.openapi.util.registry.RegistryValue;
@@ -87,6 +88,21 @@ public class CompilerEncodingServiceTest extends JavaPsiTestCase {
     assertEquals(StandardCharsets.ISO_8859_1, file.getCharset());
   }
 
+  public void testBigPropertiesAutoEncoding() throws IOException {
+    final VirtualFile file = createFile("test.properties");
+
+    WriteAction.run(() -> {
+      @SuppressWarnings("NonAsciiCharacters")
+      byte[] bytes = "verifyEmail.tooltip=初回ログイン後またはアドレスの変更が送信された後に、ユーザーに自分の電子メールアドレスを確認するように要求します。\n"
+        .repeat(64).getBytes(StandardCharsets.UTF_8);
+      file.setBinaryContent(bytes);
+    });
+
+    LoadTextUtil.loadText(file, 1024);
+    assertEquals(StandardCharsets.UTF_8, file.getCharset());
+
+  }
+
 
   public void testPropertiesEncodingFeatureFlagTest() {
     RegistryValue registryValue = Registry.get("properties.file.encoding.legacy.support");

platform/core-api/src/com/intellij/openapi/fileTypes/CharsetUtil.java

@@ -125,12 +125,7 @@ public final class CharsetUtil {
       .onUnmappableCharacter(CodingErrorAction.REPORT)
       .onMalformedInput(CodingErrorAction.REPORT);
 
-    CoderResult result = decoder.decode(byteBuffer, decodedBuffer, true);
-    if (result.isError()) {
-      return TextRange.from(byteBuffer.position(), result.length());
-    }
-
-    result = decoder.flush(decodedBuffer);
+    CoderResult result = decoder.decode(byteBuffer, decodedBuffer, false);
     if (result.isError()) {
       return TextRange.from(byteBuffer.position(), result.length());
     }