Repo created

TMessagesProj/jni/voip/webrtc/base/process/environment_internal.cc

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+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/process/environment_internal.h"
+
+#include <stddef.h>
+
+#include <vector>
+
+namespace base {
+namespace internal {
+
+namespace {
+
+#if defined(OS_POSIX) || defined(OS_FUCHSIA) || defined(OS_WIN)
+// Parses a null-terminated input string of an environment block. The key is
+// placed into the given string, and the total length of the line, including
+// the terminating null, is returned.
+size_t ParseEnvLine(const NativeEnvironmentString::value_type* input,
+                    NativeEnvironmentString* key) {
+  // Skip to the equals or end of the string, this is the key.
+  size_t cur = 0;
+  while (input[cur] && input[cur] != '=')
+    cur++;
+  *key = NativeEnvironmentString(&input[0], cur);
+
+  // Now just skip to the end of the string.
+  while (input[cur])
+    cur++;
+  return cur + 1;
+}
+#endif
+
+}  // namespace
+
+#if defined(OS_POSIX) || defined(OS_FUCHSIA)
+
+std::unique_ptr<char* []> AlterEnvironment(const char* const* const env,
+                                           const EnvironmentMap& changes) {
+  std::string value_storage;  // Holds concatenated null-terminated strings.
+  std::vector<size_t> result_indices;  // Line indices into value_storage.
+
+  // First build up all of the unchanged environment strings. These are
+  // null-terminated of the form "key=value".
+  std::string key;
+  for (size_t i = 0; env[i]; i++) {
+    size_t line_length = ParseEnvLine(env[i], &key);
+
+    // Keep only values not specified in the change vector.
+    auto found_change = changes.find(key);
+    if (found_change == changes.end()) {
+      result_indices.push_back(value_storage.size());
+      value_storage.append(env[i], line_length);
+    }
+  }
+
+  // Now append all modified and new values.
+  for (const auto& i : changes) {
+    if (!i.second.empty()) {
+      result_indices.push_back(value_storage.size());
+      value_storage.append(i.first);
+      value_storage.push_back('=');
+      value_storage.append(i.second);
+      value_storage.push_back(0);
+    }
+  }
+
+  size_t pointer_count_required =
+      result_indices.size() + 1 +  // Null-terminated array of pointers.
+      (value_storage.size() + sizeof(char*) - 1) / sizeof(char*);  // Buffer.
+  std::unique_ptr<char*[]> result(new char*[pointer_count_required]);
+
+  // The string storage goes after the array of pointers.
+  char* storage_data =
+      reinterpret_cast<char*>(&result.get()[result_indices.size() + 1]);
+  if (!value_storage.empty())
+    memcpy(storage_data, value_storage.data(), value_storage.size());
+
+  // Fill array of pointers at the beginning of the result.
+  for (size_t i = 0; i < result_indices.size(); i++)
+    result[i] = &storage_data[result_indices[i]];
+  result[result_indices.size()] = 0;  // Null terminator.
+
+  return result;
+}
+
+#elif defined(OS_WIN)
+
+NativeEnvironmentString AlterEnvironment(const wchar_t* env,
+                                         const EnvironmentMap& changes) {
+  NativeEnvironmentString result;
+
+  // First build up all of the unchanged environment strings.
+  const wchar_t* ptr = env;
+  while (*ptr) {
+    std::wstring key;
+    size_t line_length = ParseEnvLine(ptr, &key);
+
+    // Keep only values not specified in the change vector.
+    if (changes.find(key) == changes.end()) {
+      result.append(ptr, line_length);
+    }
+    ptr += line_length;
+  }
+
+  // Now append all modified and new values.
+  for (const auto& i : changes) {
+    // Windows environment blocks cannot handle keys or values with NULs.
+    CHECK_EQ(std::wstring::npos, i.first.find(L'\0'));
+    CHECK_EQ(std::wstring::npos, i.second.find(L'\0'));
+    if (!i.second.empty()) {
+      result += i.first;
+      result.push_back('=');
+      result += i.second;
+      result.push_back('\0');
+    }
+  }
+
+  // Add the terminating NUL.
+  result.push_back('\0');
+  return result;
+}
+
+#endif  // OS_POSIX || OS_FUCHSIA
+
+}  // namespace internal
+}  // namespace base