mfbt/Utf8.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "mozilla/Maybe.h"
   8 #include "mozilla/TextUtils.h"
   9 #include "mozilla/Types.h"
  10 #include "mozilla/Utf8.h"
  11
  12 #include <stddef.h>
  13 #include <stdint.h>
  14
  15 MFBT_API bool
  16 mozilla::IsValidUtf8(const void* aCodeUnits, size_t aCount)
  17 {
  18   const auto* s = static_cast<const unsigned char*>(aCodeUnits);
  19   const auto* const limit = s + aCount;
  20
  21   while (s < limit) {
  22     unsigned char c = *s++;
  23
  24     // If the first byte is ASCII, it's the only one in the code point.  Have a
  25     // fast path that avoids all the rest of the work and looping in that case.
  26     if (IsAscii(c)) {
  27       continue;
  28     }
  29
  30     Maybe<char32_t> maybeCodePoint =
  31       DecodeOneUtf8CodePoint(Utf8Unit(c), &s, limit);
  32     if (maybeCodePoint.isNothing()) {
  33       return false;
  34     }
  35   }
  36
  37   MOZ_ASSERT(s == limit);
  38   return true;
  39 }