win: Implement CrashpadClient::StartHandler()

util/win/command_line.cc

+// Copyright 2015 The Crashpad Authors. All rights reserved.
+//
+// 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 "util/win/command_line.h"
+
+namespace crashpad {
+
+// Ref:
+// http://blogs.msdn.com/b/twistylittlepassagesallalike/archive/2011/04/23/everyone-quotes-arguments-the-wrong-way.aspx
+void AppendCommandLineArgument(const std::wstring& argument,
+                               std::wstring* command_line) {
+  if (!command_line->empty()) {
+    command_line->push_back(L' ');
+  }
+
+  // Don’t bother quoting if unnecessary.
+  if (!argument.empty() &&
+      argument.find_first_of(L" \t\n\v\"") == std::wstring::npos) {
+    command_line->append(argument);
+  } else {
+    command_line->push_back(L'"');
+    for (std::wstring::const_iterator i = argument.begin();; ++i) {
+      size_t backslash_count = 0;
+      while (i != argument.end() && *i == L'\\') {
+        ++i;
+        ++backslash_count;
+      }
+      if (i == argument.end()) {
+        // Escape all backslashes, but let the terminating double quotation mark
+        // we add below be interpreted as a metacharacter.
+        command_line->append(backslash_count * 2, L'\\');
+        break;
+      } else if (*i == L'"') {
+        // Escape all backslashes and the following double quotation mark.
+        command_line->append(backslash_count * 2 + 1, L'\\');
+        command_line->push_back(*i);
+      } else {
+        // Backslashes aren’t special here.
+        command_line->append(backslash_count, L'\\');
+        command_line->push_back(*i);
+      }
+    }
+    command_line->push_back(L'"');
+  }
+}
+
+}  // namespace crashpad