deps/v8: Apply REPLACE_INVALID_UTF8 patch

- https://codereview.chromium.org/121173009/
- https://code.google.com/p/v8/source/detail?r=18683

Note: The v8 test case did not cleanly apply, so it's missing from this
patch. I'm assuming this is not a problem if the v8 test suite is not
part of the node build / test system. If that's the case I'll fix it.
Otherwise the test case will be integrated once v8 is upgraded.

deps/v8/include/v8.h

@@ -1076,7 +1076,11 @@ class String : public Primitive {
     NO_OPTIONS = 0,
     HINT_MANY_WRITES_EXPECTED = 1,
     NO_NULL_TERMINATION = 2,
-    PRESERVE_ASCII_NULL = 4
+    PRESERVE_ASCII_NULL = 4,
+    // Used by WriteUtf8 to replace orphan surrogate code units with the
+    // unicode replacement character. Needs to be set to guarantee valid UTF-8
+    // output.
+    REPLACE_INVALID_UTF8 = 8
   };
 
   // 16-bit character codes.

deps/v8/src/api.cc

@@ -3759,7 +3759,8 @@ static int RecursivelySerializeToUtf8(i::String* string,
                                       int end,
                                       int recursion_budget,
                                       int32_t previous_character,
-                                      int32_t* last_character) {
+                                      int32_t* last_character,
+                                      bool replace_invalid_utf8) {
   int utf8_bytes = 0;
   while (true) {
     if (string->IsAsciiRepresentation()) {
@@ -3775,7 +3776,10 @@ static int RecursivelySerializeToUtf8(i::String* string,
         for (int i = start; i < end; i++) {
           uint16_t character = data[i];
           current +=
-              unibrow::Utf8::Encode(current, character, previous_character);
+              unibrow::Utf8::Encode(current,
+                                    character,
+                                    previous_character,
+                                    replace_invalid_utf8);
           previous_character = character;
         }
         *last_character = previous_character;
@@ -3788,7 +3792,10 @@ static int RecursivelySerializeToUtf8(i::String* string,
         for (int i = start; i < end; i++) {
           uint16_t character = data[i];
           current +=
-              unibrow::Utf8::Encode(current, character, previous_character);
+              unibrow::Utf8::Encode(current,
+                                    character,
+                                    previous_character,
+                                    replace_invalid_utf8);
           previous_character = character;
         }
         *last_character = previous_character;
@@ -3824,7 +3831,8 @@ static int RecursivelySerializeToUtf8(i::String* string,
                                          boundary,
                                          recursion_budget - 1,
                                          previous_character,
-                                         &previous_character);
+                                         &previous_character,
+                                         replace_invalid_utf8);
           if (extra_utf8_bytes < 0) return extra_utf8_bytes;
           buffer += extra_utf8_bytes;
           utf8_bytes += extra_utf8_bytes;
@@ -3879,7 +3887,10 @@ int String::WriteUtf8(char* buffer,
     return len;
   }
 
-  if (capacity == -1 || capacity / 3 >= string_length) {
+  bool replace_invalid_utf8 = (options & REPLACE_INVALID_UTF8);
+  int max16BitCodeUnitSize = unibrow::Utf8::kMax16BitCodeUnitSize;
+
+  if (capacity == -1 || capacity / max16BitCodeUnitSize >= string_length) {
     int32_t previous = unibrow::Utf16::kNoPreviousCharacter;
     const int kMaxRecursion = 100;
     int utf8_bytes =
@@ -3889,7 +3900,8 @@ int String::WriteUtf8(char* buffer,
                                    string_length,
                                    kMaxRecursion,
                                    previous,
-                                   &previous);
+                                   &previous,
+                                   replace_invalid_utf8);
     if (utf8_bytes >= 0) {
       // Success serializing with recursion.
       if ((options & NO_NULL_TERMINATION) == 0 &&
@@ -3942,14 +3954,16 @@ int String::WriteUtf8(char* buffer,
     char intermediate[unibrow::Utf8::kMaxEncodedSize];
     for (; i < len && pos < capacity; i++) {
       i::uc32 c = write_input_buffer.GetNext();
-      if (unibrow::Utf16::IsTrailSurrogate(c) &&
-          unibrow::Utf16::IsLeadSurrogate(previous)) {
+      if (unibrow::Utf16::IsSurrogatePair(previous, c)) {
         // We can't use the intermediate buffer here because the encoding
         // of surrogate pairs is done under assumption that you can step
         // back and fix the UTF8 stream.  Luckily we only need space for one
         // more byte, so there is always space.
         ASSERT(pos < capacity);
-        int written = unibrow::Utf8::Encode(buffer + pos, c, previous);
+        int written = unibrow::Utf8::Encode(buffer + pos,
+                                            c,
+                                            previous,
+                                            replace_invalid_utf8);
         ASSERT(written == 1);
         pos += written;
         nchars++;
@@ -3957,7 +3971,8 @@ int String::WriteUtf8(char* buffer,
         int written =
             unibrow::Utf8::Encode(intermediate,
                                   c,
-                                  unibrow::Utf16::kNoPreviousCharacter);
+                                  unibrow::Utf16::kNoPreviousCharacter,
+                                  replace_invalid_utf8);
         if (pos + written <= capacity) {
           for (int j = 0; j < written; j++) {
             buffer[pos + j] = intermediate[j];

deps/v8/src/unicode-inl.h

@@ -79,7 +79,10 @@ template <class T, int s> int Mapping<T, s>::CalculateValue(uchar c, uchar n,
 }
 
 
-unsigned Utf8::Encode(char* str, uchar c, int previous) {
+unsigned Utf8::Encode(char* str,
+                      uchar c,
+                      int previous,
+                      bool replace_invalid) {
   static const int kMask = ~(1 << 6);
   if (c <= kMaxOneByteChar) {
     str[0] = c;
@@ -89,12 +92,16 @@ unsigned Utf8::Encode(char* str, uchar c, int previous) {
     str[1] = 0x80 | (c & kMask);
     return 2;
   } else if (c <= kMaxThreeByteChar) {
-    if (Utf16::IsTrailSurrogate(c) &&
-        Utf16::IsLeadSurrogate(previous)) {
+    if (Utf16::IsSurrogatePair(previous, c)) {
       const int kUnmatchedSize = kSizeOfUnmatchedSurrogate;
       return Encode(str - kUnmatchedSize,
                     Utf16::CombineSurrogatePair(previous, c),
-                    Utf16::kNoPreviousCharacter) - kUnmatchedSize;
+                    Utf16::kNoPreviousCharacter,
+                    replace_invalid) - kUnmatchedSize;
+    } else if (replace_invalid &&
+               (Utf16::IsLeadSurrogate(c) ||
+               Utf16::IsTrailSurrogate(c))) {
+      c = kBadChar;
     }
     str[0] = 0xE0 | (c >> 12);
     str[1] = 0x80 | ((c >> 6) & kMask);

deps/v8/src/unicode.h

@@ -117,6 +117,9 @@ class Buffer {
 
 class Utf16 {
  public:
+  static inline bool IsSurrogatePair(int lead, int trail) {
+    return IsLeadSurrogate(lead) && IsTrailSurrogate(trail);
+  }
   static inline bool IsLeadSurrogate(int code) {
     if (code == kNoPreviousCharacter) return false;
     return (code & 0xfc00) == 0xd800;
@@ -152,13 +155,19 @@ class Utf16 {
 class Utf8 {
  public:
   static inline uchar Length(uchar chr, int previous);
-  static inline unsigned Encode(
-      char* out, uchar c, int previous);
+  static inline unsigned Encode(char* out,
+                                uchar c,
+                                int previous,
+                                bool replace_invalid = false);
   static const byte* ReadBlock(Buffer<const char*> str, byte* buffer,
       unsigned capacity, unsigned* chars_read, unsigned* offset);
   static uchar CalculateValue(const byte* str,
                               unsigned length,
                               unsigned* cursor);
+
+
+  // The unicode replacement character, used to signal invalid unicode
+  // sequences (e.g. an orphan surrogate) when converting to a UTF-8 encoding.
   static const uchar kBadChar = 0xFFFD;
   static const unsigned kMaxEncodedSize   = 4;
   static const unsigned kMaxOneByteChar   = 0x7f;
@@ -170,6 +179,9 @@ class Utf8 {
   // that match are coded as a 4 byte UTF-8 sequence.
   static const unsigned kBytesSavedByCombiningSurrogates = 2;
   static const unsigned kSizeOfUnmatchedSurrogate = 3;
+  // The maximum size a single UTF-16 code unit may take up when encoded as
+  // UTF-8.
+  static const unsigned kMax16BitCodeUnitSize  = 3;
 
  private:
   template <unsigned s> friend class Utf8InputBuffer;