1 files changed, 106 insertions, 0 deletions
diff --git a/third_party/wasm2c/src/utf8.cc b/third_party/wasm2c/src/utf8.cc
new file mode 100644
index 0000000000..dd95c8c63d
--- /dev/null
+++ b/third_party/wasm2c/src/utf8.cc
@@ -0,0 +1,106 @@
+/*
+ * Copyright 2017 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "wabt/utf8.h"
+
+#include <cstdint>
+
+namespace wabt {
+
+namespace {
+
+// clang-format off
+const int s_utf8_length[256] = {
+ // 0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // 0x00
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // 0x10
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // 0x20
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // 0x30
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // 0x40
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // 0x50
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // 0x60
+    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,  // 0x70
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  // 0x80
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  // 0x90
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  // 0xa0
+    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  // 0xb0
+    0, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,  // 0xc0
+    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,  // 0xd0
+    3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,  // 0xe0
+    4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,  // 0xf0
+};
+// clang-format on
+
+// Returns true if this is a valid continuation byte.
+bool IsCont(uint8_t c) {
+  return (c & 0xc0) == 0x80;
+}
+
+}  // end anonymous namespace
+
+bool IsValidUtf8(const char* s, size_t s_length) {
+  const uint8_t* p = reinterpret_cast<const uint8_t*>(s);
+  const uint8_t* end = p + s_length;
+  while (p < end) {
+    uint8_t cu0 = *p;
+    int length = s_utf8_length[cu0];
+    if (p + length > end) {
+      return false;
+    }
+
+    switch (length) {
+      case 0:
+        return false;
+
+      case 1:
+        p++;
+        break;
+
+      case 2:
+        p++;
+        if (!IsCont(*p++)) {
+          return false;
+        }
+        break;
+
+      case 3: {
+        p++;
+        uint8_t cu1 = *p++;
+        uint8_t cu2 = *p++;
+        if (!(IsCont(cu1) && IsCont(cu2)) ||
+            (cu0 == 0xe0 && cu1 < 0xa0) ||  // Overlong encoding.
+            (cu0 == 0xed && cu1 >= 0xa0))   // UTF-16 surrogate halves.
+          return false;
+        break;
+      }
+
+      case 4: {
+        p++;
+        uint8_t cu1 = *p++;
+        uint8_t cu2 = *p++;
+        uint8_t cu3 = *p++;
+        if (!(IsCont(cu1) && IsCont(cu2) && IsCont(cu3)) ||
+            (cu0 == 0xf0 && cu1 < 0x90) ||  // Overlong encoding.
+            (cu0 == 0xf4 && cu1 >= 0x90))   // Code point >= 0x11000.
+          return false;
+        break;
+      }
+    }
+  }
+  return true;
+}
+
+}  // namespace wabt