Add truncation support to Zeroconf with test.

src/networkremote/zeroconf.cpp

@@ -14,6 +14,8 @@
 #include "tinysvcmdns.h"
 #endif
 
+#include <QTextCodec>
+
 Zeroconf* Zeroconf::sInstance = NULL;
 
 Zeroconf::~Zeroconf() {
@@ -35,3 +37,18 @@ Zeroconf* Zeroconf::GetZeroconf() {
 
   return sInstance;
 }
+
+QByteArray Zeroconf::TruncateName(const QString& name) {
+  QTextCodec* codec = QTextCodec::codecForName("UTF-8");
+  QByteArray truncated_utf8;
+  foreach (QChar c, name) {
+    QByteArray rendered = codec->fromUnicode(&c, 1, NULL);
+    if (truncated_utf8.size() + rendered.size() >= 63) {
+      break;
+    }
+    truncated_utf8 += rendered;
+  }
+  // NULL-terminate the string.
+  truncated_utf8.append('\0');
+  return truncated_utf8;
+}

src/networkremote/zeroconf.h

@@ -15,6 +15,9 @@ class Zeroconf {
 
   static Zeroconf* GetZeroconf();
 
+  // Truncate a QString to 63 bytes of UTF-8.
+  static QByteArray TruncateName(const QString& name);
+
  private:
   static Zeroconf* sInstance;
 };

tests/CMakeLists.txt

@@ -143,6 +143,7 @@ add_test_file(utilities_test.cpp false)
 #add_test_file(xspfparser_test.cpp false)
 add_test_file(closure_test.cpp false)
 add_test_file(concurrentrun_test.cpp false)
+add_test_file(zeroconf_test.cpp false)
 
 #if(LINUX AND HAVE_DBUS)
 #  add_test_file(mpris1_test.cpp true)

tests/zeroconf_test.cpp

@@ -0,0 +1,42 @@
+#include "gtest/gtest.h"
+
+#include "networkremote/zeroconf.h"
+
+namespace {
+
+static const char k64CharAscii[] =
+    "aaaaaaaaaaaaaaaa"
+    "aaaaaaaaaaaaaaaa"
+    "aaaaaaaaaaaaaaaa"
+    "aaaaaaaaaaaaaaaa";
+
+static const char kShortMultiByteString[] =
+    "我会说一点汉语";
+
+static const char kLongMultiByteString[] =
+    "我会说一点汉语"
+    "我会说一点汉语"
+    "我会说一点汉语"
+    "我会说一点汉语";
+
+TEST(ZeroconfTest, TruncatesAscii) {
+  QByteArray truncated = Zeroconf::TruncateName(
+      QString::fromAscii(k64CharAscii));
+  EXPECT_EQ(63, truncated.size());
+  EXPECT_TRUE(truncated.endsWith('\0'));
+}
+
+TEST(ZeroconfTest, DoesNotTruncateShortMultiByteUTF8) {
+  EXPECT_EQ(
+      sizeof(kShortMultiByteString),
+      Zeroconf::TruncateName(QString::fromUtf8(kShortMultiByteString)).size());
+}
+
+TEST(ZeroconfTest, TruncatesLongMultiByteUTF8) {
+  QByteArray truncated = Zeroconf::TruncateName(
+      QString::fromAscii(kLongMultiByteString));
+  EXPECT_LE(63, truncated.size());
+  EXPECT_TRUE(truncated.endsWith('\0'));
+}
+
+}  // namespace