Move ScriptTag and RCTJSModulesUnbundle to cxxreact

Reviewed By: javache

Differential Revision: D4213662

fbshipit-source-id: fc2ec9717c24fe77bb022a48777049f88173ebeb

ReactCommon/cxxreact/JSIndexedRAMBundle.cpp

@@ -0,0 +1,92 @@
+// Copyright 2004-present Facebook. All Rights Reserved.
+
+#include "JSIndexedRAMBundle.h"
+#include "oss-compat-util.h"
+
+namespace facebook {
+namespace react {
+
+JSIndexedRAMBundle::JSIndexedRAMBundle(const char *sourcePath) :
+    m_bundle (sourcePath, std::ios_base::in) {
+  if (!m_bundle) {
+    throw std::ios_base::failure(
+      toString("Bundle ", sourcePath,
+               "cannot be opened: ", m_bundle.rdstate()));
+  }
+
+  // read in magic header, number of entries, and length of the startup section
+  uint32_t header[3];
+  static_assert(
+    sizeof(header) == 12,
+    "header size must exactly match the input file format");
+
+  readBundle(reinterpret_cast<char *>(header), sizeof(header));
+  const size_t numTableEntries = littleEndianToHost(header[1]);
+  const size_t startupCodeSize = littleEndianToHost(header[2]);
+
+  // allocate memory for meta data and lookup table.
+  m_table = ModuleTable(numTableEntries);
+  m_baseOffset = sizeof(header) + m_table.byteLength();
+
+  // read the lookup table from the file
+  readBundle(
+    reinterpret_cast<char *>(m_table.data.get()), m_table.byteLength());
+
+  // read the startup code
+  m_startupCode =
+    std::make_unique<facebook::react::JSBigBufferString>(startupCodeSize);
+
+  readBundle(m_startupCode->data(), startupCodeSize);
+}
+
+JSIndexedRAMBundle::Module JSIndexedRAMBundle::getModule(uint32_t moduleId) const {
+  Module ret;
+  ret.name = toString(moduleId, ".js");
+  ret.code = getModuleCode(moduleId);
+  return ret;
+}
+
+std::unique_ptr<const facebook::react::JSBigString> JSIndexedRAMBundle::getStartupCode() {
+  CHECK(m_startupCode) << "startup code for a RAM Bundle can only be retrieved once";
+  return std::move(m_startupCode);
+}
+
+std::string JSIndexedRAMBundle::getModuleCode(const uint32_t id) const {
+  const auto moduleData = id < m_table.numEntries ? &m_table.data[id] : nullptr;
+
+  // entries without associated code have offset = 0 and length = 0
+  const uint32_t length = moduleData ? littleEndianToHost(moduleData->length) : 0;
+  if (length == 0) {
+    throw std::ios_base::failure(
+      toString("Error loading module", id, "from RAM Bundle"));
+  }
+
+  std::string ret(moduleData->length, '\0');
+  readBundle(&ret.front(), length, m_baseOffset + littleEndianToHost(moduleData->offset));
+  return ret;
+}
+
+void JSIndexedRAMBundle::readBundle(char *buffer, const std::streamsize bytes) const {
+  if (!m_bundle.read(buffer, bytes)) {
+    if (m_bundle.rdstate() & std::ios::eofbit) {
+      throw std::ios_base::failure("Unexpected end of RAM Bundle file");
+    }
+    throw std::ios_base::failure(
+      toString("Error reading RAM Bundle: ", m_bundle.rdstate()));
+  }
+}
+
+void JSIndexedRAMBundle::readBundle(
+    char *buffer,
+    const std::streamsize bytes,
+    const std::ifstream::pos_type position) const {
+
+  if (!m_bundle.seekg(position)) {
+    throw std::ios_base::failure(
+      toString("Error reading RAM Bundle: ", m_bundle.rdstate()));
+  }
+  readBundle(buffer, bytes);
+}
+
+}  // namespace react
+}  // namespace facebook