Fix crashing bug due to the fact that external one byte strings cannot be escaped

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/cpu.h"
@@ skipping 13226 matching lines @@
       }
     }
   }
 }
 
 
 RawString* String::EscapeSpecialCharacters(const String& str) {
   if (str.IsOneByteString()) {
     return OneByteString::EscapeSpecialCharacters(str);
   }
-  ASSERT(str.IsTwoByteString());
-  return TwoByteString::EscapeSpecialCharacters(str);
+  if (str.IsTwoByteString()) {
+    return TwoByteString::EscapeSpecialCharacters(str);
+  }
+  if (str.IsExternalOneByteString()) {
+    return ExternalOneByteString::EscapeSpecialCharacters(str);
+  }
+  ASSERT(str.IsExternalTwoByteString());
+  // If EscapeSpecialCharacters is frequently called on external two byte
+  // strings, we should implement it directly on ExternalTwoByteString rather
+  // than first converting to a TwoByteString.
+  return TwoByteString::EscapeSpecialCharacters(
+      String::Handle(TwoByteString::New(str, Heap::kNew)));
 }
 
 
 RawString* String::NewFormatted(const char* format, ...) {
   va_list args;
   va_start(args, format);
   RawString* result = NewFormattedV(format, args);
   NoGCScope no_gc;
   va_end(args);
   return result;
@@ skipping 384 matching lines @@
   }
   index_ = end_;
   return false;
 }
 
 
 RawOneByteString* OneByteString::EscapeSpecialCharacters(const String& str) {
   intptr_t len = str.Length();
   if (len > 0) {
     intptr_t num_escapes = 0;
-    intptr_t index = 0;
     for (intptr_t i = 0; i < len; i++) {
       if (IsSpecialCharacter(*CharAddr(str, i))) {
         num_escapes += 1;
       }
     }
     const String& dststr = String::Handle(
         OneByteString::New(len + num_escapes, Heap::kNew));
+    intptr_t index = 0;
     for (intptr_t i = 0; i < len; i++) {
       if (IsSpecialCharacter(*CharAddr(str, i))) {
         *(CharAddr(dststr, index)) = '\\';
         *(CharAddr(dststr, index + 1)) = SpecialCharacter(*CharAddr(str, i));
         index += 2;
       } else {
         *(CharAddr(dststr, index)) = *CharAddr(str, i);
         index += 1;
       }
     }
     return OneByteString::raw(dststr);
   }
-  return OneByteString::null();
+  return OneByteString::New(0, Heap::kNew);
+}
+
+RawOneByteString* ExternalOneByteString::EscapeSpecialCharacters(
+    const String& str) {
+  intptr_t len = str.Length();
+  if (len > 0) {
+    intptr_t num_escapes = 0;
+    for (intptr_t i = 0; i < len; i++) {
+      if (IsSpecialCharacter(*CharAddr(str, i))) {
+        num_escapes += 1;
+      }
+    }
+    const String& dststr = String::Handle(
+        OneByteString::New(len + num_escapes, Heap::kNew));
+    intptr_t index = 0;
+    for (intptr_t i = 0; i < len; i++) {
+      if (IsSpecialCharacter(*CharAddr(str, i))) {
+        *(OneByteString::CharAddr(dststr, index)) = '\\';
+        *(OneByteString::CharAddr(dststr, index + 1)) =
+        SpecialCharacter(*CharAddr(str, i));
+        index += 2;
+      } else {
+        *(OneByteString::CharAddr(dststr, index)) = *CharAddr(str, i);
+        index += 1;
+      }
+    }
+    return OneByteString::raw(dststr);
+  }
+  return OneByteString::New(0, Heap::kNew);
 }
 
 
 RawOneByteString* OneByteString::New(intptr_t len,
                                      Heap::Space space) {
   ASSERT(Isolate::Current() == Dart::vm_isolate() ||
          Isolate::Current()->object_store()->one_byte_string_class() !=
          Class::null());
   if (len < 0 || len > kMaxElements) {
     // This should be caught before we reach here.
@@ skipping 156 matching lines @@
 void OneByteString::Finalize(Dart_WeakPersistentHandle handle, void* peer) {
   delete reinterpret_cast<ExternalStringData<uint8_t>*>(peer);
   DeleteWeakPersistentHandle(handle);
 }
 
 
 RawTwoByteString* TwoByteString::EscapeSpecialCharacters(const String& str) {
   intptr_t len = str.Length();
   if (len > 0) {
     intptr_t num_escapes = 0;
-    intptr_t index = 0;
     for (intptr_t i = 0; i < len; i++) {
       if (IsSpecialCharacter(*CharAddr(str, i))) {
         num_escapes += 1;
       }
     }
     const String& dststr = String::Handle(
         TwoByteString::New(len + num_escapes, Heap::kNew));
+    intptr_t index = 0;
     for (intptr_t i = 0; i < len; i++) {
       if (IsSpecialCharacter(*CharAddr(str, i))) {
         *(CharAddr(dststr, index)) = '\\';
         *(CharAddr(dststr, index + 1)) = SpecialCharacter(*CharAddr(str, i));
         index += 2;
       } else {
         *(CharAddr(dststr, index)) = *CharAddr(str, i);
         index += 1;
       }
     }
     return TwoByteString::raw(dststr);
   }
-  return TwoByteString::null();
+  return TwoByteString::New(0, Heap::kNew);
 }
 
 
 RawTwoByteString* TwoByteString::New(intptr_t len,
                                      Heap::Space space) {
   ASSERT(Isolate::Current()->object_store()->two_byte_string_class());
   if (len < 0 || len > kMaxElements) {
     // This should be caught before we reach here.
     FATAL1("Fatal error in TwoByteString::New: invalid len %" Pd "\n", len);
   }
@@ skipping 1299 matching lines @@
   return "_MirrorReference";
 }
 
 
 void MirrorReference::PrintToJSONStream(JSONStream* stream, bool ref) const {
   JSONObject jsobj(stream);
 }
 
 
 }  // namespace dart