Gigantic descriptors shouldn't overflow the Java string literal size limit.

java/pom.xml

@@ -112,6 +112,7 @@
                   <arg value="../src/google/protobuf/unittest_lite.proto" />
                   <arg value="../src/google/protobuf/unittest_import_lite.proto" />
                   <arg value="../src/google/protobuf/unittest_lite_imports_nonlite.proto" />
+                  <arg value="../src/google/protobuf/unittest_enormous_descriptor.proto" />
                 </exec>
               </tasks>
               <testSourceRoot>target/generated-test-sources</testSourceRoot>

java/src/main/java/com/google/protobuf/Descriptors.java

@@ -244,7 +244,8 @@ public final class Descriptors {
      * encoded in protocol buffer wire format.
      */
     public static void internalBuildGeneratedFileFrom(
-        final String descriptorData, final FileDescriptor[] dependencies,
+        final String[] descriptorDataParts,
+        final FileDescriptor[] dependencies,
         final InternalDescriptorAssigner descriptorAssigner) {
       // Hack:  We can't embed a raw byte array inside generated Java code
       //   (at least, not efficiently), but we can embed Strings.  So, the
@@ -255,9 +256,16 @@ public final class Descriptors {
       //   serialized form.  So, if we convert it to bytes in ISO-8859-1, we
       //   should get the original bytes that we want.
 
+      // descriptorData may contain multiple strings in order to get around the
+      // Java 64k string literal limit.
+      StringBuilder descriptorData = new StringBuilder();
+      for (String part : descriptorDataParts) {
+        descriptorData.append(part);
+      }
+
       final byte[] descriptorBytes;
       try {
-        descriptorBytes = descriptorData.getBytes("ISO-8859-1");
+        descriptorBytes = descriptorData.toString().getBytes("ISO-8859-1");
       } catch (UnsupportedEncodingException e) {
         throw new RuntimeException(
           "Standard encoding ISO-8859-1 not supported by JVM.", e);

java/src/test/java/com/google/protobuf/DescriptorsTest.java

@@ -397,4 +397,12 @@ public class DescriptorsTest extends TestCase {
       assertEquals(values1[i].toString(), values2[i].toString());
     }
   }
+
+  public void testEnormousDescriptor() throws Exception {
+    // The descriptor for this file is larger than 64k, yet it did not cause
+    // a compiler error due to an over-long string literal.
+    assertTrue(
+        UnittestEnormousDescriptor.getDescriptor()
+          .toProto().getSerializedSize() > 65536);
+  }
 }

src/Makefile.am

@@ -186,6 +186,7 @@ protoc_inputs =                                                \
   google/protobuf/unittest_lite.proto                          \
   google/protobuf/unittest_import_lite.proto                   \
   google/protobuf/unittest_lite_imports_nonlite.proto          \
+  google/protobuf/unittest_enormous_descriptor.proto           \
   google/protobuf/compiler/cpp/cpp_test_bad_identifiers.proto
 
 EXTRA_DIST =                                                   \
@@ -225,6 +226,8 @@ protoc_outputs =                                               \
   google/protobuf/unittest_custom_options.pb.h                 \
   google/protobuf/unittest_lite_imports_nonlite.pb.cc          \
   google/protobuf/unittest_lite_imports_nonlite.pb.h           \
+  google/protobuf/unittest_enormous_descriptor.pb.cc           \
+  google/protobuf/unittest_enormous_descriptor.pb.h            \
   google/protobuf/compiler/cpp/cpp_test_bad_identifiers.pb.cc  \
   google/protobuf/compiler/cpp/cpp_test_bad_identifiers.pb.h
 

src/google/protobuf/compiler/java/java_file.cc

@@ -256,20 +256,28 @@ void FileGenerator::GenerateEmbeddedDescriptor(io::Printer* printer) {
     "private static com.google.protobuf.Descriptors.FileDescriptor\n"
     "    descriptor;\n"
     "static {\n"
-    "  java.lang.String descriptorData =\n");
+    "  java.lang.String[] descriptorData = {\n");
   printer->Indent();
   printer->Indent();
 
   // Only write 40 bytes per line.
   static const int kBytesPerLine = 40;
   for (int i = 0; i < file_data.size(); i += kBytesPerLine) {
-    if (i > 0) printer->Print(" +\n");
+    if (i > 0) {
+      // Every 400 lines, start a new string literal, in order to avoid the
+      // 64k length limit.
+      if (i % 400 == 0) {
+        printer->Print(",\n");
+      } else {
+        printer->Print(" +\n");
+      }
+    }
     printer->Print("\"$data$\"",
       "data", CEscape(file_data.substr(i, kBytesPerLine)));
   }
-  printer->Print(";\n");
 
   printer->Outdent();
+  printer->Print("\n};\n");
 
   // -----------------------------------------------------------------
   // Create the InternalDescriptorAssigner.