Extract BuildHandlerArgvStrings to common shared location

I plan to have Fuchsia use a "StartHandlerAtCrash" style similar to
Linux, so pull the argv preservation out into a location where it can be
shared between crashpad_client_linux.cc and crashpad_client_fuchsia.cc
(in upcoming sets).

Bug: crashpad:196
Change-Id: Ie305556579d9ac2c97b205ecf63cadf069228811
Reviewed-on: https://chromium-review.googlesource.com/1002860
Commit-Queue: Scott Graham <scottmg@chromium.org>
Reviewed-by: Joshua Peraza <jperaza@chromium.org>

client/BUILD.gn

@@ -52,7 +52,11 @@ static_library("client") {
   }
 
   if (crashpad_is_linux || crashpad_is_android || crashpad_is_fuchsia) {
-    sources += [ "crashpad_info_note.S" ]
+    sources += [
+      "client_argv_handling.cc",
+      "client_argv_handling.h",
+      "crashpad_info_note.S",
+    ]
   }
 
   if (crashpad_is_win) {
@@ -64,9 +68,7 @@ static_library("client") {
   }
 
   if (crashpad_is_fuchsia) {
-    sources += [
-      "crashpad_client_fuchsia.cc",
-    ]
+    sources += [ "crashpad_client_fuchsia.cc" ]
   }
 
   if (crashpad_is_linux || crashpad_is_android || crashpad_is_fuchsia) {

client/client_argv_handling.cc

@@ -0,0 +1,74 @@
+// Copyright 2018 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 "client/client_argv_handling.h"
+
+#include "base/strings/stringprintf.h"
+
+namespace crashpad {
+
+namespace {
+
+std::string FormatArgumentString(const std::string& name,
+                                 const std::string& value) {
+  return base::StringPrintf("--%s=%s", name.c_str(), value.c_str());
+}
+
+}  // namespace
+
+void BuildHandlerArgvStrings(
+    const base::FilePath& handler,
+    const base::FilePath& database,
+    const base::FilePath& metrics_dir,
+    const std::string& url,
+    const std::map<std::string, std::string>& annotations,
+    const std::vector<std::string>& arguments,
+    std::vector<std::string>* argv_strings) {
+  argv_strings->clear();
+
+  argv_strings->push_back(handler.value());
+  for (const auto& argument : arguments) {
+    argv_strings->push_back(argument);
+  }
+
+  if (!database.empty()) {
+    argv_strings->push_back(FormatArgumentString("database", database.value()));
+  }
+
+  if (!metrics_dir.empty()) {
+    argv_strings->push_back(
+        FormatArgumentString("metrics-dir", metrics_dir.value()));
+  }
+
+  if (!url.empty()) {
+    argv_strings->push_back(FormatArgumentString("url", url));
+  }
+
+  for (const auto& kv : annotations) {
+    argv_strings->push_back(
+        FormatArgumentString("annotation", kv.first + '=' + kv.second));
+  }
+}
+
+void ConvertArgvStrings(const std::vector<std::string>& argv_strings,
+                        std::vector<const char*>* argv) {
+  argv->clear();
+  argv->reserve(argv_strings.size() + 1);
+  for (const auto& arg : argv_strings) {
+    argv->push_back(arg.c_str());
+  }
+  argv->push_back(nullptr);
+}
+
+}  // namespace crashpad

client/client_argv_handling.h

@@ -0,0 +1,53 @@
+// Copyright 2018 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.
+
+#ifndef CRASHPAD_CLIENT_CLIENT_ARGV_HANDLING_H_
+#define CRASHPAD_CLIENT_CLIENT_ARGV_HANDLING_H_
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "base/files/file_path.h"
+
+namespace crashpad {
+
+//! \brief Builds a vector of arguments suitable for invoking a handler process
+//!     based on arguments passed to StartHandler-type().
+//!
+//! See StartHandlerAtCrash() for documentation on the input arguments.
+//!
+//! \param[out] A argv_strings vector of arguments suitable for starting the
+//!     handler with.
+void BuildHandlerArgvStrings(
+    const base::FilePath& handler,
+    const base::FilePath& database,
+    const base::FilePath& metrics_dir,
+    const std::string& url,
+    const std::map<std::string, std::string>& annotations,
+    const std::vector<std::string>& arguments,
+    std::vector<std::string>* argv_strings);
+
+//! \brief Flattens a string vector into a const char* vector suitable for use
+//!     in an exec() call.
+//!
+//! \param[in] argv_strings Arguments to be passed to child process, typically
+//!     created by BuildHandlerArgvStrings().
+//! \param[out] argv argv suitable for starting the child process.
+void ConvertArgvStrings(const std::vector<std::string>& argv_strings,
+                        std::vector<const char*>* argv);
+
+}  // namespace crashpad
+
+#endif  // CRASHPAD_CLIENT_CLIENT_ARGV_HANDLING_H_

client/crashpad_client_linux.cc

@@ -24,6 +24,7 @@
 
 #include "base/logging.h"
 #include "base/strings/stringprintf.h"
+#include "client/client_argv_handling.h"
 #include "util/file/file_io.h"
 #include "util/linux/exception_handler_client.h"
 #include "util/linux/exception_information.h"
@@ -36,11 +37,6 @@ namespace crashpad {
 
 namespace {
 
-std::string FormatArgumentString(const std::string& name,
-                                 const std::string& value) {
-  return base::StringPrintf("--%s=%s", name.c_str(), value.c_str());
-}
-
 std::string FormatArgumentInt(const std::string& name, int value) {
   return base::StringPrintf("--%s=%d", name.c_str(), value);
 }
@@ -49,50 +45,6 @@ std::string FormatArgumentAddress(const std::string& name, void* addr) {
   return base::StringPrintf("--%s=%p", name.c_str(), addr);
 }
 
-void BuildHandlerArgvStrings(
-    const base::FilePath& handler,
-    const base::FilePath& database,
-    const base::FilePath& metrics_dir,
-    const std::string& url,
-    const std::map<std::string, std::string>& annotations,
-    const std::vector<std::string>& arguments,
-    std::vector<std::string>* argv_strings) {
-  argv_strings->clear();
-
-  argv_strings->push_back(handler.value());
-  for (const auto& argument : arguments) {
-    argv_strings->push_back(argument);
-  }
-
-  if (!database.empty()) {
-    argv_strings->push_back(FormatArgumentString("database", database.value()));
-  }
-
-  if (!metrics_dir.empty()) {
-    argv_strings->push_back(
-        FormatArgumentString("metrics-dir", metrics_dir.value()));
-  }
-
-  if (!url.empty()) {
-    argv_strings->push_back(FormatArgumentString("url", url));
-  }
-
-  for (const auto& kv : annotations) {
-    argv_strings->push_back(
-        FormatArgumentString("annotation", kv.first + '=' + kv.second));
-  }
-}
-
-void ConvertArgvStrings(const std::vector<std::string>& argv_strings,
-                        std::vector<const char*>* argv) {
-  argv->clear();
-  argv->reserve(argv_strings.size() + 1);
-  for (const auto& arg : argv_strings) {
-    argv->push_back(arg.c_str());
-  }
-  argv->push_back(nullptr);
-}
-
 class SignalHandler {
  public:
   virtual void HandleCrashFatal(int signo,