1 files changed, 156 insertions, 0 deletions
diff --git a/intl/uconv/nsNCRFallbackEncoderWrapper.cpp b/intl/uconv/nsNCRFallbackEncoderWrapper.cpp
new file mode 100644
index 000000000..7b83b72e8
--- /dev/null
+++ b/intl/uconv/nsNCRFallbackEncoderWrapper.cpp
@@ -0,0 +1,156 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "nsNCRFallbackEncoderWrapper.h"
+
+#include "mozilla/dom/EncodingUtils.h"
+
+nsNCRFallbackEncoderWrapper::nsNCRFallbackEncoderWrapper(const nsACString& aEncoding)
+ : mEncoder(mozilla::dom::EncodingUtils::EncoderForEncoding(aEncoding))
+{
+}
+
+nsNCRFallbackEncoderWrapper::~nsNCRFallbackEncoderWrapper()
+{
+}
+
+bool
+nsNCRFallbackEncoderWrapper::WriteNCR(nsACString& aBytes,
+                                      uint32_t& aDstWritten,
+                                      int32_t aUnmappable)
+{
+  // To avoid potentially shrinking aBytes and then growing it back, use
+  // another string for number formatting.
+  nsAutoCString ncr("&#");
+  ncr.AppendInt(aUnmappable);
+  ncr.Append(';');
+  uint32_t ncrLen = ncr.Length();
+  uint32_t needed = aDstWritten + ncrLen;
+  if (needed > INT32_MAX) {
+    return false;
+  }
+  if (needed > aBytes.Length() && !aBytes.SetLength(needed,
+                                                    mozilla::fallible_t())) {
+    return false;
+  }
+  memcpy(aBytes.BeginWriting() + aDstWritten,
+         ncr.BeginReading(),
+         ncrLen);
+  aDstWritten += ncrLen;
+  return true;
+}
+
+bool
+nsNCRFallbackEncoderWrapper::Encode(const nsAString& aUtf16,
+                                    nsACString& aBytes)
+{
+  // mozilla::dom::EncodingUtils::EncoderForEncoding fails during shutdown
+  if (!mEncoder) {
+    return false;
+  }
+  // nsIUnicodeEncoder uses int32_t for sizes :-(
+  if (aUtf16.Length() > INT32_MAX) {
+    return false;
+  }
+  const char16_t* src = aUtf16.BeginReading();
+  const char16_t* srcEnd = aUtf16.EndReading();
+  uint32_t dstWritten = 0;
+  for (;;) {
+    int32_t srcLen = srcEnd - src;
+    int32_t dstLen = 0;
+    nsresult rv = mEncoder->GetMaxLength(src, srcLen, &dstLen);
+    if (NS_FAILED(rv)) {
+      return false;
+    }
+    uint32_t needed = dstWritten + dstLen;
+    if (needed > INT32_MAX) {
+      return false;
+    }
+    // Behind the scenes SetLength() makes the underlying allocation not have
+    // slop, so we don't need to round up here.
+    if (needed > aBytes.Length() && !aBytes.SetLength(needed,
+                                                      mozilla::fallible_t())) {
+      return false;
+    }
+    // We need to re-obtain the destination pointer on every iteration, because
+    // SetLength() invalidates it.
+    char* dst = aBytes.BeginWriting() + dstWritten;
+    dstLen = aBytes.Length() - dstWritten;
+    mEncoder->Reset();
+    rv = mEncoder->Convert(src, &srcLen, dst, &dstLen);
+    // Update state tracking
+    src += srcLen;
+    dstWritten += dstLen;
+    if (rv == NS_OK_UENC_MOREOUTPUT) {
+      MOZ_ASSERT_UNREACHABLE("GetMaxLength must have returned a bogus length.");
+      return false;
+    }
+    if (rv == NS_ERROR_UENC_NOMAPPING) {
+      int32_t unmappable;
+      // The unmappable code unit or the first half of an unmappable surrogate
+      // pair is consumed by the encoder.
+      MOZ_ASSERT(srcLen > 0, "Encoder should have consumed some input.");
+      char16_t codeUnit = src[-1];
+      // Let's see if it is a surrogate
+      size_t highBits = (codeUnit & 0xFC00);
+      if (highBits == 0xD800) {
+        // high surrogate
+        // Let's see if we actually have a surrogate pair.
+        char16_t next;
+        if (src < srcEnd && NS_IS_LOW_SURROGATE((next = *src))) {
+          src++; // consume the low surrogate
+          unmappable = SURROGATE_TO_UCS4(codeUnit, next);
+        } else {
+          // unpaired surrogate.
+          unmappable = 0xFFFD;
+        }
+      } else if (highBits == 0xDC00) {
+        // low surrogate
+        // This must be an unpaired surrogate.
+        unmappable = 0xFFFD;
+      } else {
+        // not a surrogate
+        unmappable = codeUnit;
+      }
+      // If we are encoding to ISO-2022-JP, we need to let the encoder to
+      // generate a transition to the ASCII state if not already there.
+      dst = aBytes.BeginWriting() + dstWritten;
+      dstLen = aBytes.Length() - dstWritten;
+      rv = mEncoder->Finish(dst, &dstLen);
+      dstWritten += dstLen;
+      if (rv != NS_OK) {
+        // Failures should be impossible if GetMaxLength works. Big5 is the
+        // only case where Finish() may return NS_ERROR_UENC_NOMAPPING but
+        // that should never happen right after Convert() has returned it.
+        MOZ_ASSERT_UNREACHABLE("Broken encoder.");
+        return false;
+      }
+      if (!WriteNCR(aBytes, dstWritten, unmappable)) {
+        return false;
+      }
+      continue;
+    }
+    if (!(rv == NS_OK || rv == NS_OK_UENC_MOREINPUT)) {
+      return false;
+    }
+    MOZ_ASSERT(src == srcEnd, "Converter did not consume all input.");
+    dst = aBytes.BeginWriting() + dstWritten;
+    dstLen = aBytes.Length() - dstWritten;
+    rv = mEncoder->Finish(dst, &dstLen);
+    dstWritten += dstLen;
+    if (rv == NS_OK_UENC_MOREOUTPUT) {
+      MOZ_ASSERT_UNREACHABLE("GetMaxLength must have returned a bogus length.");
+      return false;
+    }
+    if (rv == NS_ERROR_UENC_NOMAPPING) {
+      // Big5
+      if (!WriteNCR(aBytes, dstWritten, 0xFFFD)) {
+        return false;
+      }
+    }
+    return aBytes.SetLength(dstWritten, mozilla::fallible_t());
+  }
+}
+