Fix Chromedriver Issue 749

chrome/test/chromedriver/chrome/adb_impl.cc

 // Copyright 2013 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 "chrome/test/chromedriver/chrome/adb_impl.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/json/string_escape.h"
 #include "base/logging.h"
@@ skipping 208 matching lines @@
       } else {
         break;
       }
     }
   }
 
   return Status(kUnknownError,
                 "Failed to get PID for the following process: " + process_name);
 }
 
+Status AdbImpl::GetDevtoolsRemoteSocket(const std::string& device_serial,
+                                        const std::string& process_name,
+                                        std::string* device_socket) {
+  // Parse 'cat /proc/net/unix' output which on Android looks like this:
+  //
+  // Num       RefCount Protocol Flags    Type St Inode Path
+  // 00000000: 00000002 00000000 00010000 0001 01 331813 /dev/socket/zygote
+  // 00000000: 00000002 00000000 00010000 0001 01 358606 @xxx_devtools_remote
+  // 00000000: 00000002 00000000 00010000 0001 01 347300 @yyy_devtools_remote
+  //
+  // We need to find records with paths starting from '@' (abstract socket)
+  // and containing the channel pattern ("_devtools_remote").
+  //
+  // The code that generates this file is in the unix_seq_show() function in
+  // net/unix/af_unix.c in the kernel source. Looking at include/net/af_unix.h
+  // is also helpful, to see the data structures in use.
+  //
+  // The socket path is always the last column in the output, and
+  // the Android Kernel source matches the stock kernel in this respect.
+

[samuong, 2016/10/20 04:40:40]

nit: no need for a blank line here

+  std::string response;
+  Status status = ExecuteHostShellCommand(device_serial,
+                                          "cat /proc/net/unix", &response);
+  std::string kDevToolsSocketSuffix = "_devtools_remote";
+  if (!status.IsOk())
+    return status;
+  for (const base::StringPiece& line :
+       base::SplitStringPiece(response, "\n", base::KEEP_WHITESPACE,
+                              base::SPLIT_WANT_NONEMPTY)) {
+    std::vector<std::string> fields =
+        base::SplitString(line, " \r", base::KEEP_WHITESPACE,
+                          base::SPLIT_WANT_NONEMPTY);
+    if (fields.size() < 8)
+      continue;
+

[samuong, 2016/10/20 04:40:40]

nit: no need for a blank line here

+    // fields[3] (Flags) != __SO_ACCEPTCON (include/uapi/net.h)
+    // fields[5] (State) != TCP_ESTABLISHED (inlclude/net/tcp_states.h)

[samuong, 2016/10/20 04:40:40]

Sorry, I still feel this is too cryptic to developers who might be reading this
in the future. Can you write these as full sentences, and just mention that
we're looking for sockets that are accepting connections and currently
unconnected?

+    if (fields[3] != "00010000" || fields[5] != "01")
+      continue;
+    std::string path_field = fields[7];
+    if (path_field.size() < 1 || path_field[0] != '@')
+      continue;
+    size_t socket_name_pos = path_field.find(kDevToolsSocketSuffix);
+    if (socket_name_pos == std::string::npos)
+      continue;
+
+    std::string socket_name = path_field.substr(1, socket_name_pos - 1);
+    if (socket_name.compare(process_name) == 0) {
+      *device_socket = path_field.substr(1);
+    }
+  }
+
+  // We could not find a device socket for the expected process name
+  if (device_socket->empty()) {
+    return Status(kUnknownError,
+                  "Failed to find remote devtools socket for: " + process_name);
+  }
+  return Status(kOk);
+}
+
 Status AdbImpl::ExecuteCommand(
     const std::string& command, std::string* response) {
   scoped_refptr<ResponseBuffer> response_buffer = new ResponseBuffer;
   VLOG(1) << "Sending adb command: " << command;
   io_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&ExecuteCommandOnIOThread, command, response_buffer, port_));
   Status status = response_buffer->GetResponse(
       response, base::TimeDelta::FromSeconds(30));
   if (status.IsOk()) {
@@ skipping 11 matching lines @@
 
 Status AdbImpl::ExecuteHostShellCommand(
     const std::string& device_serial,
     const std::string& shell_command,
     std::string* response) {
   return ExecuteCommand(
       "host:transport:" + device_serial + "|shell:" + shell_command,
       response);
 }