[Platform/Android] Read the adb server from an env variable if set

[lanza]

Summary

The environment variable ANDROID_ADB_SERVER_PORT can be defined to have
adbd litsen on a different port. Teach lldb how to understand this via
simply checking the env var.

[clayborg]

Should we do this via a "settings set" setting instead of an environment variable? This would make it easier to test running a test suite kind of situation.

[clayborg]

Also is this the server that runs on the host machine where LLDB resides, or remotely on the device? If this is something that would be done at "platform connect" time, each platform can have its own unique options and arguments to "platform connect". Might be better to just add them as options to the "platform connect" command. Something like:

(lldb) platform connect --adb-port 5037 --adb-path /path/to/adb --device MyPixel2

[clayborg]

Added Pavel since he previously worked on Android LLDB at Google. Pavel, please add any additional reviewers to this patch that you think might be interested.

[srhines]

Thanks for improving this for LLDB and Android.

[labath]

This looks good. I believe @srhines is the best person to review android-related things right now. I can also help with the lldb side of things.

lldb/trunk/source/Plugins/Platform/Android/AdbClient.cpp

void AdbClient::SetDeviceID(const std::string &device_id) {
   m_device_id = device_id;
 }
 
 const std::string &AdbClient::GetDeviceID() const { return m_device_id; }
 
 Status AdbClient::Connect() {
   Status error;
   m_conn.reset(new ConnectionFileDescriptor);
-  m_conn->Connect("connect://localhost:5037", &error);
+  std::string port = "5037";
+  if (const char *env_port = std::getenv("ANDROID_ADB_SERVER_PORT")) {
+    port = env_port;
+  }
+  std::string uri = "connect://localhost:" + port;
+  m_conn->Connect(uri.c_str(), &error);
 
   return error;
 }
 
 Status AdbClient::GetDevices(DeviceIDList &device_list) {
   device_list.clear();
 
   auto error = SendMessage("host:devices");