Add domain socket support to gdb-remote protocol and lldb-server.

[ovyalov]

Summary

This CL provides logic for running lldb-server on domain sockets and required gdb-remote infrastructure changes (qLaunchGDBServer request in particular).
Main highlights:

• Make lldb-server to listen either on TCP and domain sockets. If colon is found in socket name (i.e. hostname:port format) lldb-server starts in TCP mode, otherwise uses domain sockets. Further improvement will be to pass a pseudo protocol prefix as part of socket name (tcp://localhost:5555 or unix-domain:///tmp/platform.sock) - this will allow to add new transport types more easily (for example, linux-abstract://socket for Linux abstract sockets).
• Add socket_name response field to qLaunchGDBServer.
• Make PlatformRemoteGDBServer to support retry-based connect - both for ConnectRemote and debug server connect. Since in case of domain sockets lldb-server doesn't write port into named pipe we cannot use it as a synchronization point - so it's possible that qLaunchGDBServer will be received by host before debug server is up and listens on socket.
• In case of Android platform rewrite input platform and gdbserver URLs with TCP URLs - i.e. connect://localhost:$local_port

[labath]

I *think* it looks good, but I find it quite hard to review a change of this size.
A wise man once said "if your commit description contains bullet points, you are doing too much". I think it would be better to split up changes like this in the future.

Make PlatformRemoteGDBServer to support retry-based connect - both for ConnectRemote and debug server connect. Since in case of domain sockets lldb-server doesn't write port into named pipe we cannot use it as a synchronization point - so it's possible that qLaunchGDBServer will be received by host before debug server is up and listens on socket.

I would like to preserve the invariant that by the time a reply to qLaunchGDBServer is received, the server is up and ready to serve connections. How about we keep this file synchronization protocol even when using domain sockets? The server could write nothing (or the socket path, or whatever) to the file when it is up and ready. That way, we don't have to increase the number of places that do those silly wait-and-retry loops. What do you think?

source/Plugins/Platform/Android/AdbClient.cpp

151

Any special quoting needed here? (e.g. if the socket name contains ':')

Although, I wouldn't be surprised if adb just falls over in that case...

source/Plugins/Platform/gdb-server/PlatformRemoteGDBServer.h

228

This comment makes no sense.

Also, given the new functionality, the function name isn't the best choice. Maybe simply LaunchGDBServer, with the comment saying that the url it listens on is returned through the second argument ?

tools/lldb-server/lldb-gdbserver.cpp

266

I like that this is finally going away.

[clayborg]

Minor nit over ordering of #include, but other than that it looks good.

source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp

36

llvm includes should go before lldb includes.

[ovyalov]

• Renamed LaunchGDBserverAndGetPort into LaunchGDBServer within PlatformAndroidRemoteGDBServer/PlatformRemoteGDBServer/GDBRemoteCommunicationClient
• Fixed includes' order.
• Added Acceptor::LocalSocketId which returns either TCP port and domain socket name - in order to write this value down into named pipe so it can be used by platform as a synchronization point.

[ovyalov]

In D13881#270878, @labath wrote:

I *think* it looks good, but I find it quite hard to review a change of this size.
A wise man once said "if your commit description contains bullet points, you are doing too much". I think it would be better to split up changes like this in the future.

Make PlatformRemoteGDBServer to support retry-based connect - both for ConnectRemote and debug server connect. Since in case of domain sockets lldb-server doesn't write port into named pipe we cannot use it as a synchronization point - so it's possible that qLaunchGDBServer will be received by host before debug server is up and listens on socket.

I would like to preserve the invariant that by the time a reply to qLaunchGDBServer is received, the server is up and ready to serve connections. How about we keep this file synchronization protocol even when using domain sockets? The server could write nothing (or the socket path, or whatever) to the file when it is up and ready. That way, we don't have to increase the number of places that do those silly wait-and-retry loops. What do you think?

I was thinking about sending a full connect URL(instead of port) via pipe from debug server to platform/lldb host - so, it can be less transport type dependent. But there are some problems here - e.g., we cannot compose TCP connect URL properly on server side because only client knows a proper server's host address (if server is sitting behind proxies/firewalls/...). So, ended up with extending Acceptor with GetLocalSocketId method which returns a string either with TCP port or socket path so we can wait until debug server is up in either case.

source/Plugins/Platform/Android/AdbClient.cpp

151

I suspect adb fails in such situation.
Let me verify it once lldb-server/Acceptor will support protocol-based URL like unix:///tmp/platform.sock. Now it's somewhat problematic because we cannot pass colon as a part of
URL - if colon is found it's treated as $host:$port pattern and TCPSocket is created.

source/Plugins/Platform/gdb-server/PlatformRemoteGDBServer.h

227–232

Done.

[labath]

looks good, thanks.

source/Plugins/Platform/Android/AdbClient.cpp

151

Ok, makes sense.

[tberghammer]

source/Plugins/Platform/gdb-server/PlatformRemoteGDBServer.cpp

39

Please don't include <thread> here if it isn't absolutely necessary as there is a bug on windows in the header.

If you need it then you will most likely have to add the same workaround I added in rL250833 to make it compile on Windows

[ovyalov]

Files:

/lldb/trunk/lldb.xcodeproj/project.pbxproj
/lldb/trunk/source/Host/posix/ConnectionFileDescriptorPosix.cpp
/lldb/trunk/source/Plugins/Platform/Android/AdbClient.cpp
/lldb/trunk/source/Plugins/Platform/Android/AdbClient.h
/lldb/trunk/source/Plugins/Platform/Android/PlatformAndroid.cpp
/lldb/trunk/source/Plugins/Platform/Android/PlatformAndroidRemoteGDBServer.cpp
/lldb/trunk/source/Plugins/Platform/Android/PlatformAndroidRemoteGDBServer.h
/lldb/trunk/source/Plugins/Platform/gdb-server/PlatformRemoteGDBServer.cpp
/lldb/trunk/source/Plugins/Platform/gdb-server/PlatformRemoteGDBServer.h
/lldb/trunk/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp
/lldb/trunk/source/Plugins/Process/gdb-remote/GDBRemoteCommunication.h
/lldb/trunk/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp
/lldb/trunk/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.h
/lldb/trunk/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp
/lldb/trunk/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.h
/lldb/trunk/source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
/lldb/trunk/tools/lldb-server/Acceptor.cpp
/lldb/trunk/tools/lldb-server/Acceptor.h
/lldb/trunk/tools/lldb-server/CMakeLists.txt
/lldb/trunk/tools/lldb-server/lldb-gdbserver.cpp
/lldb/trunk/tools/lldb-server/lldb-platform.cpp

Users:

ovyalov (Author)

http://reviews.llvm.org/rL250933

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source/Host/posix/ConnectionFileDescriptorPosix.cpp

 #include "lldb/Core/Log.h"
 #include "lldb/Core/StreamString.h"
 #include "lldb/Core/Timer.h"
 #include "lldb/Host/Host.h"
 #include "lldb/Host/Socket.h"
 #include "lldb/Host/common/TCPSocket.h"
 #include "lldb/Interpreter/Args.h"
 
-#include "Utility/UriParser.h"
-
 using namespace lldb;
 using namespace lldb_private;
 
 ConnectionFileDescriptor::ConnectionFileDescriptor(bool child_processes_inherit)
     : Connection()
     , m_pipe()
     , m_mutex(Mutex::eMutexTypeRecursive)
     , m_shutting_down(false)
if (s && s[0])
             // unix://SOCKNAME
             return NamedSocketAccept(s + strlen("accept://"), error_ptr);
         }
         else if (strstr(s, "unix-accept://") == s)
         {
             // unix://SOCKNAME
             return NamedSocketAccept(s + strlen("unix-accept://"), error_ptr);
         }
-        else if (strstr(s, "adb://") == s)
-        {
-            int port = -1;
-            std::string scheme, host, path;
-            if (!UriParser::Parse(s, scheme, host, port, path))
-            {
-                if (error_ptr)
-                    error_ptr->SetErrorStringWithFormat("Failed to parse URL '%s'", s);
-                return eConnectionStatusError;
-            }
-            std::ostringstream host_and_port;
-            host_and_port << "localhost:" << port;
-            return ConnectTCP(host_and_port.str().c_str(), error_ptr);
-        }
         else if (strstr(s, "connect://") == s)
         {
             return ConnectTCP(s + strlen("connect://"), error_ptr);
         }
         else if (strstr(s, "tcp-connect://") == s)
         {
             return ConnectTCP(s + strlen("tcp-connect://"), error_ptr);
         }
         else if (strstr(s, "udp://") == s)
         {
             return ConnectUDP(s + strlen("udp://"), error_ptr);
         }
+        else if (strstr(s, "unix-connect://") == s)
+        {
+            // unix-connect://SOCKNAME
+            return NamedSocketConnect(s + strlen("unix-connect://"), error_ptr);
+        }
 #ifndef LLDB_DISABLE_POSIX
         else if (strstr(s, "fd://") == s)
         {
             // Just passing a native file descriptor within this current process
             // that is already opened (possibly from a service or other source).
             s += strlen("fd://");
             bool success = false;
             int fd = StringConvert::ToSInt32(s, -1, 0, &success);

source/Plugins/Platform/Android/AdbClient.h

public:
 
     Error
     GetDevices (DeviceIDList &device_list);
 
     Error
     SetPortForwarding (const uint16_t local_port, const uint16_t remote_port);
 
     Error
+    SetPortForwarding (const uint16_t local_port, const char* remote_socket_name);
+
+    Error
     DeletePortForwarding (const uint16_t local_port);
 
     Error
     PullFile (const FileSpec &remote_file, const FileSpec &local_file);
 
     Error
     PushFile (const FileSpec &local_file, const FileSpec &remote_file);
 

source/Plugins/Platform/Android/AdbClient.cpp

AdbClient::SetPortForwarding (const uint16_t local_port, const uint16_t remote_port)
     const auto error = SendDeviceMessage (message);
     if (error.Fail ())
         return error;
 
     return ReadResponseStatus ();
 }
 
 Error
+AdbClient::SetPortForwarding (const uint16_t local_port, const char* remote_socket_name)
+{
+    char message[PATH_MAX];
+    snprintf (message, sizeof (message), "forward:tcp:%d;localfilesystem:%s", local_port, remote_socket_name);
+
+    const auto error = SendDeviceMessage (message);
+    if (error.Fail ())
+        return error;
+
+    return ReadResponseStatus ();
+}
+
+Error
 AdbClient::DeletePortForwarding (const uint16_t local_port)
 {
     char message[32];
     snprintf (message, sizeof (message), "killforward:tcp:%d", local_port);
 
     const auto error = SendDeviceMessage (message);
     if (error.Fail ())
         return error;

source/Plugins/Platform/Android/PlatformAndroid.cpp

PlatformAndroid::ConnectRemote(Args& args)
 
     int port;
     std::string scheme, host, path;
     const char *url = args.GetArgumentAtIndex(0);
     if (!url)
         return Error("URL is null.");
     if (!UriParser::Parse(url, scheme, host, port, path))
         return Error("Invalid URL: %s", url);
-    if (scheme == "adb")
-        m_device_id = host;
 
     auto error = PlatformLinux::ConnectRemote(args);
     if (error.Success())
     {
         AdbClient adb;
         error = AdbClient::CreateByDeviceID(m_device_id, adb);
         if (error.Fail())
             return error;

source/Plugins/Platform/Android/PlatformAndroidRemoteGDBServer.h

public:
 
     Error
     DisconnectRemote () override;
 
 protected:
     std::string m_device_id;
     std::map<lldb::pid_t, uint16_t> m_port_forwards;
 
-    uint16_t
-    LaunchGDBserverAndGetPort (lldb::pid_t &pid) override;
+    bool
+    LaunchGDBserverAndGetPort (lldb::pid_t &pid, std::string &connect_url) override;
 
     bool
     KillSpawnedProcess (lldb::pid_t pid) override;
 
     void
     DeleteForwardPort (lldb::pid_t pid);
 
-    std::string
-    MakeUrl(const char* scheme,
-            const char* hostname,
-            uint16_t port,
-            const char* path) override;
-
     Error
-    SetPortForwarding(const lldb::pid_t pid, const uint16_t remote_port, uint16_t &local_port);
+    MakeConnectURL(const lldb::pid_t pid,
+                   const uint16_t remote_port,
+                   const char* remote_socket_name,
+                   std::string& connect_url);
 
 private:
     DISALLOW_COPY_AND_ASSIGN (PlatformAndroidRemoteGDBServer);
 
 };
 
 } // namespace platform_android
 } // namespace lldb_private
 
 #endif  // liblldb_PlatformAndroidRemoteGDBServer_h_

source/Plugins/Platform/Android/PlatformAndroidRemoteGDBServer.cpp

 
 using namespace lldb;
 using namespace lldb_private;
 using namespace platform_android;
 
 static const lldb::pid_t g_remote_platform_pid = 0; // Alias for the process id of lldb-platform
 
 static Error
-ForwardPortWithAdb (const uint16_t local_port, const uint16_t remote_port, std::string& device_id)
+ForwardPortWithAdb (const uint16_t local_port,
+                    const uint16_t remote_port,
+                    const char* remote_socket_name,
+                    std::string& device_id)
 {
     Log *log(GetLogIfAllCategoriesSet (LIBLLDB_LOG_PLATFORM));
 
     AdbClient adb;
     auto error = AdbClient::CreateByDeviceID(device_id, adb);
     if (error.Fail ())
         return error;
 
     device_id = adb.GetDeviceID();
     if (log)
         log->Printf("Connected to Android device \"%s\"", device_id.c_str ());
 
+    if (remote_port != 0)
+    {
+        if (log)
+            log->Printf("Forwarding remote TCP port %d to local TCP port %d", remote_port, local_port);
         return adb.SetPortForwarding(local_port, remote_port);
     }
 
+    if (log)
+        log->Printf("Forwarding remote socket \"%s\" to local TCP port %d", remote_socket_name, local_port);
+    return adb.SetPortForwarding(local_port, remote_socket_name);
+}
+
 static Error
 DeleteForwardPortWithAdb (uint16_t local_port, const std::string& device_id)
 {
     AdbClient adb (device_id);
     return adb.DeletePortForwarding (local_port);
 }
 
 static Error

 }
 
 PlatformAndroidRemoteGDBServer::~PlatformAndroidRemoteGDBServer ()
 {
     for (const auto& it : m_port_forwards)
         DeleteForwardPortWithAdb(it.second, m_device_id);
 }
 
-uint16_t
-PlatformAndroidRemoteGDBServer::LaunchGDBserverAndGetPort (lldb::pid_t &pid)
+bool
+PlatformAndroidRemoteGDBServer::LaunchGDBserverAndGetPort (lldb::pid_t &pid, std::string &connect_url)
 {
-    uint16_t remote_port = m_gdb_client.LaunchGDBserverAndGetPort (pid, "127.0.0.1");
-    if (remote_port == 0)
-        return remote_port;
+    uint16_t remote_port = 0;
+    std::string socket_name;
+    if (!m_gdb_client.LaunchGDBserverAndGetPort ("127.0.0.1", pid, remote_port, socket_name))
+        return false;
 
-    uint16_t local_port = 0;
-    auto error = SetPortForwarding (pid, remote_port, local_port);
-    return error.Success() ? local_port : 0;
+    Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PLATFORM));
+
+    auto error = MakeConnectURL (pid,
+                                 remote_port,
+                                 socket_name.c_str (),
+                                 connect_url);
+    if (error.Success() && log)
+        log->Printf("gdbserver connect URL: %s", connect_url.c_str());
+
+    return error.Success();
 }
 
 bool
 PlatformAndroidRemoteGDBServer::KillSpawnedProcess (lldb::pid_t pid)
 {
     DeleteForwardPort (pid);
     return m_gdb_client.KillSpawnedProcess (pid);
 }
 
 Error
 PlatformAndroidRemoteGDBServer::ConnectRemote (Args& args)
 {
     m_device_id.clear();
 
     if (args.GetArgumentCount() != 1)
         return Error("\"platform connect\" takes a single argument: <connect-url>");
 
     int remote_port;
     std::string scheme, host, path;
     const char *url = args.GetArgumentAtIndex (0);
     if (!url)
         return Error("URL is null.");
     if (!UriParser::Parse (url, scheme, host, remote_port, path))
         return Error("Invalid URL: %s", url);
-    if (scheme == "adb")
-        m_device_id = host;
 
-    uint16_t local_port = 0;
-    auto error = SetPortForwarding (g_remote_platform_pid, remote_port, local_port);
+    std::string connect_url;
+    auto error = MakeConnectURL (g_remote_platform_pid,
+                                 (remote_port < 0) ? 0 : remote_port,
+                                 path.c_str (),
+                                 connect_url);
+
     if (error.Fail ())
         return error;
 
-    const std::string new_url = MakeUrl(
-        scheme.c_str(), host.c_str(), local_port, path.c_str());
-    args.ReplaceArgumentAtIndex (0, new_url.c_str ());
+    args.ReplaceArgumentAtIndex (0, connect_url.c_str ());
 
     Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PLATFORM));
     if (log)
-        log->Printf("Rewritten URL: %s", new_url.c_str());
+        log->Printf("Rewritten platform connect URL: %s", connect_url.c_str());
 
     error = PlatformRemoteGDBServer::ConnectRemote(args);
     if (error.Fail ())
         DeleteForwardPort (g_remote_platform_pid);
 
     return error;
 }
 
if (error.Fail()) {
         if (log)
             log->Printf("Failed to delete port forwarding (pid=%" PRIu64 ", port=%d, device=%s): %s",
                          pid, port, m_device_id.c_str(), error.AsCString());
     }
     m_port_forwards.erase(it);
 }
 
 Error
-PlatformAndroidRemoteGDBServer::SetPortForwarding(const lldb::pid_t pid,
-                                                  const uint16_t remote_port,
-                                                  uint16_t &local_port)
+PlatformAndroidRemoteGDBServer::MakeConnectURL(const lldb::pid_t pid,
+                                               const char* remote_socket_name,
+                                               std::string& connect_url)
 {
     static const int kAttempsNum = 5;
 
     Error error;
     // There is a race possibility that somebody will occupy
     // a port while we're in between FindUnusedPort and ForwardPortWithAdb -
     // adding the loop to mitigate such problem.
     for (auto i = 0; i < kAttempsNum; ++i)
     {
+        uint16_t local_port = 0;
         error = FindUnusedPort(local_port);
         if (error.Fail())
             return error;
 
-        error = ForwardPortWithAdb(local_port, remote_port, m_device_id);
+        error = ForwardPortWithAdb(local_port, remote_port, remote_socket_name, m_device_id);
         if (error.Success())
         {
             m_port_forwards[pid] = local_port;
+            std::ostringstream url_str;
+            url_str << "connect://localhost:" << local_port;
+            connect_url = url_str.str();
             break;
         }
     }
 
     return error;
 }
-
-std::string
-PlatformAndroidRemoteGDBServer::MakeUrl(const char* scheme,
-                                        const char* hostname,
-                                        uint16_t port,
-                                        const char* path)
-{
-    std::ostringstream hostname_str;
-    if (!strcmp(scheme, "adb"))
-        hostname_str << "[" << hostname << "]";
-    else
-        hostname_str << hostname;
-
-    return PlatformRemoteGDBServer::MakeUrl(scheme,
-                                            hostname_str.str().c_str(),
-                                            port,
-                                            path);
-}

source/Plugins/Platform/gdb-server/PlatformRemoteGDBServer.h

 
 protected:
     process_gdb_remote::GDBRemoteCommunicationClient m_gdb_client;
     std::string m_platform_description; // After we connect we can get a more complete description of what we are connected to
     std::string m_platform_scheme;
     std::string m_platform_hostname;
 
     lldb::UnixSignalsSP m_remote_signals_sp;
 
-    // Launch the lldb-gdbserver on the remote host and return the port it is listening on or 0 on
-    // failure. Subclasses should override this method if they want to do extra actions before or
+    // Launch the lldb-gdbserver on the remote host and return true it is listening on
+    // Subclasses should override this method if they want to do extra actions before or
     // after launching the lldb-gdbserver.
-    virtual uint16_t
-    LaunchGDBserverAndGetPort (lldb::pid_t &pid);
+    virtual bool
+    LaunchGDBserverAndGetPort (lldb::pid_t &pid, std::string &connect_url);
 
     virtual bool
     KillSpawnedProcess (lldb::pid_t pid);
 
     virtual std::string
     MakeUrl(const char* scheme,
             const char* hostname,
             uint16_t port,
             const char* path);
 
 private:
     std::string
     MakeGdbServerUrl(const std::string &platform_scheme,
                      const std::string &platform_hostname,
-                     uint16_t port);
+                     uint16_t port,
+                     const char* socket_name);
 
     DISALLOW_COPY_AND_ASSIGN (PlatformRemoteGDBServer);
 
 };
 
 } // namespace platform_gdb_server
 } // namespace lldb_private
 
 #endif  // liblldb_PlatformRemoteGDBServer_h_

source/Plugins/Platform/gdb-server/PlatformRemoteGDBServer.cpp

 #include "lldb/Host/StringConvert.h"
 #include "lldb/Target/Process.h"
 #include "lldb/Target/Target.h"
 
 #include "Utility/UriParser.h"
 
 #include "Plugins/Process/Utility/GDBRemoteSignals.h"
 
+#include <chrono>
+#include <functional>
+#include <thread>
+
 using namespace lldb;
 using namespace lldb_private;
 using namespace lldb_private::platform_gdb_server;
 
 static bool g_initialized = false;
 
+namespace {
+
+const int kNumRetries = 10;
+const auto kWaitTimeout = std::chrono::milliseconds(500);
+
+Error
+ConnectWithRetries(const std::function<Error()> &connect_func) {
+    Error error;
+    for (int i = 0; i < kNumRetries; ++i)
+    {
+        error = connect_func();
+        if (error.Success())
+            break;
+        std::this_thread::sleep_for(kWaitTimeout);
+    }
+    return error;
+}
+
+}
+
 void
 PlatformRemoteGDBServer::Initialize ()
 {
     Platform::Initialize ();
 
     if (g_initialized == false)
     {
         g_initialized = true;
else
             int port;
             std::string path;
             const char *url = args.GetArgumentAtIndex(0);
             if (!url)
                 return Error("URL is null.");
             if (!UriParser::Parse(url, m_platform_scheme, m_platform_hostname, port, path))
                 return Error("Invalid URL: %s", url);
 
-            const ConnectionStatus status = m_gdb_client.Connect(url, &error);
-            if (status == eConnectionStatusSuccess)
+            error = ConnectWithRetries([&](){
+                Error e;
+                const ConnectionStatus status = m_gdb_client.Connect(url, &e);
+                if (status != eConnectionStatusSuccess)
+                    e.SetErrorStringWithFormat("Received invalid connection status: %d", status);
+                return e;
+            });
+            if (error.Success())
             {
                 if (m_gdb_client.HandshakeWithServer(&error))
                 {
                     m_gdb_client.GetHostInfo();
                     // If a working directory was set prior to connecting, send it down now
                     if (m_working_dir)
                         m_gdb_client.SetWorkingDir(m_working_dir);
                 }
PlatformRemoteGDBServer::DebugProcess (ProcessLaunchInfo &launch_info,
                                        Error &error)
 {
     lldb::ProcessSP process_sp;
     if (IsRemote())
     {
         if (IsConnected())
         {
             lldb::pid_t debugserver_pid = LLDB_INVALID_PROCESS_ID;
-            uint16_t port = LaunchGDBserverAndGetPort(debugserver_pid);
-
-            if (port == 0)
+            std::string connect_url;
+            if (!LaunchGDBserverAndGetPort(debugserver_pid, connect_url))
             {
                 error.SetErrorStringWithFormat ("unable to launch a GDB server on '%s'", GetHostname ());
             }
             else
             {
                 if (target == NULL)
                 {
                     TargetSP new_target_sp;
if (IsRemote())
                     debugger.GetTargetList().SetSelectedTarget(target);
                     
                     // The darwin always currently uses the GDB remote debugger plug-in
                     // so even when debugging locally we are debugging remotely!
                     process_sp = target->CreateProcess (launch_info.GetListenerForProcess(debugger), "gdb-remote", NULL);
                     
                     if (process_sp)
                     {
-                        std::string connect_url =
-                            MakeGdbServerUrl(m_platform_scheme, m_platform_hostname, port);
-                        error = process_sp->ConnectRemote (nullptr, connect_url.c_str());
-                        // Retry the connect remote one time...
-                        if (error.Fail())
-                            error = process_sp->ConnectRemote (nullptr, connect_url.c_str());
+                        error = ConnectWithRetries([&](){
+                            return process_sp->ConnectRemote (nullptr, connect_url.c_str());
+                        });
                         if (error.Success())
                             error = process_sp->Launch(launch_info);
                         else if (debugserver_pid != LLDB_INVALID_PROCESS_ID)
                         {
                             printf ("error: connect remote failed (%s)\n", error.AsCString());
                             KillSpawnedProcess(debugserver_pid);
                         }
                     }
                 }
             }
         }
         else
         {
             error.SetErrorString("not connected to remote gdb server");
         }
     }
     return process_sp;
 
 }
 
-uint16_t
-PlatformRemoteGDBServer::LaunchGDBserverAndGetPort (lldb::pid_t &pid)
+bool
+PlatformRemoteGDBServer::LaunchGDBserverAndGetPort (lldb::pid_t &pid, std::string &connect_url)
 {
     ArchSpec remote_arch = GetRemoteSystemArchitecture ();
     llvm::Triple &remote_triple = remote_arch.GetTriple ();
+
+    uint16_t port = 0;
+    std::string socket_name;
+    bool launch_result = false;
     if (remote_triple.getVendor () == llvm::Triple::Apple && remote_triple.getOS () == llvm::Triple::IOS)
     {
         // When remote debugging to iOS, we use a USB mux that always talks
         // to localhost, so we will need the remote debugserver to accept connections
         // only from localhost, no matter what our current hostname is
-        return m_gdb_client.LaunchGDBserverAndGetPort (pid, "127.0.0.1");
+        launch_result = m_gdb_client.LaunchGDBserverAndGetPort ("127.0.0.1", pid, port, socket_name);
     }
     else
     {
         // All other hosts should use their actual hostname
-        return m_gdb_client.LaunchGDBserverAndGetPort (pid, NULL);
+        launch_result = m_gdb_client.LaunchGDBserverAndGetPort (nullptr, pid, port, socket_name);
     }
+
+    if (!launch_result)
+        return false;
+
+    connect_url = MakeGdbServerUrl(m_platform_scheme,
+                                   m_platform_hostname,
+                                   port,
+                                   (socket_name.empty()) ? nullptr : socket_name.c_str());
+    return true;
 }
 
 bool
 PlatformRemoteGDBServer::KillSpawnedProcess (lldb::pid_t pid)
 {
     return m_gdb_client.KillSpawnedProcess (pid);
 }
 
 lldb::ProcessSP
 PlatformRemoteGDBServer::Attach (ProcessAttachInfo &attach_info,
                                  Debugger &debugger,
                                  Target *target,       // Can be NULL, if NULL create a new target, else use existing one
                                  Error &error)
 {
     lldb::ProcessSP process_sp;
     if (IsRemote())
     {
         if (IsConnected())
         {
             lldb::pid_t debugserver_pid = LLDB_INVALID_PROCESS_ID;
-            uint16_t port = LaunchGDBserverAndGetPort(debugserver_pid);
-
-            if (port == 0)
+            std::string connect_url;
+            if (!LaunchGDBserverAndGetPort(debugserver_pid, connect_url))
             {
                 error.SetErrorStringWithFormat ("unable to launch a GDB server on '%s'", GetHostname ());
             }
             else
             {
                 if (target == NULL)
                 {
                     TargetSP new_target_sp;
if (IsRemote())
                     debugger.GetTargetList().SetSelectedTarget(target);
                     
                     // The darwin always currently uses the GDB remote debugger plug-in
                     // so even when debugging locally we are debugging remotely!
                     process_sp = target->CreateProcess (attach_info.GetListenerForProcess(debugger), "gdb-remote", NULL);
                     
                     if (process_sp)
                     {
-                        std::string connect_url =
-                            MakeGdbServerUrl(m_platform_scheme, m_platform_hostname, port);
-                        error = process_sp->ConnectRemote(nullptr, connect_url.c_str());
+                        error = ConnectWithRetries([&](){
+                            return process_sp->ConnectRemote (nullptr, connect_url.c_str());
+                        });
                         if (error.Success())
                         {
                             auto listener = attach_info.GetHijackListener();
                             if (listener != nullptr)
                                 process_sp->HijackProcessEvents(listener.get());
                             error = process_sp->Attach(attach_info);
                         }
 
if (done)
         m_remote_signals_sp = std::move(remote_signals_sp);
 
     return m_remote_signals_sp;
 }
 
 std::string
 PlatformRemoteGDBServer::MakeGdbServerUrl(const std::string &platform_scheme,
                                           const std::string &platform_hostname,
-                                          uint16_t port)
+                                          uint16_t port,
+                                          const char* socket_name)
 {
     const char *override_scheme = getenv("LLDB_PLATFORM_REMOTE_GDB_SERVER_SCHEME");
     const char *override_hostname = getenv("LLDB_PLATFORM_REMOTE_GDB_SERVER_HOSTNAME");
     const char *port_offset_c_str = getenv("LLDB_PLATFORM_REMOTE_GDB_SERVER_PORT_OFFSET");
     int port_offset = port_offset_c_str ? ::atoi(port_offset_c_str) : 0;
 
     return MakeUrl(override_scheme ? override_scheme : platform_scheme.c_str(),
                    override_hostname ? override_hostname : platform_hostname.c_str(),
                    port + port_offset,
-                   nullptr);
+                   socket_name);
 }
 
 std::string
 PlatformRemoteGDBServer::MakeUrl(const char* scheme,
-                                       const char* hostname,
-                                       uint16_t port,
-                                       const char* path)
 {
     StreamString result;
-    result.Printf("%s://%s:%u", scheme, hostname, port);
+    result.Printf("%s://%s", scheme, hostname);
+    if (port != 0)
+        result.Printf(":%u", port);
     if (path)
         result.Write(path, strlen(path));
     return result.GetString();
 }

source/Plugins/Process/gdb-remote/GDBRemoteCommunication.h

public:
     {
         return m_packet_timeout * TimeValue::MicroSecPerSec;
     }
     //------------------------------------------------------------------
     // Start a debugserver instance on the current host using the
     // supplied connection URL.
     //------------------------------------------------------------------
     Error
-    StartDebugserverProcess (const char *hostname,
-                             uint16_t in_port, // If set to zero, then out_port will contain the bound port on exit
+    StartDebugserverProcess (const char *url,
                              Platform *platform, // If non NULL, then check with the platform for the GDB server binary if it can't be located
                              ProcessLaunchInfo &launch_info,
-                             uint16_t &out_port);
+                             uint16_t *port);
 
     void
     DumpHistory(Stream &strm);
     
 protected:
 
     class History
     {

source/Plugins/Process/gdb-remote/GDBRemoteCommunication.cpp

if (connection)
         // Do the listen on another thread so we can continue on...
         if (connection->Connect(comm->m_listen_url.c_str(), &error) != eConnectionStatusSuccess)
             comm->SetConnection(NULL);
     }
     return NULL;
 }
 
 Error
-GDBRemoteCommunication::StartDebugserverProcess (const char *hostname,
-                                                 uint16_t in_port,
+GDBRemoteCommunication::StartDebugserverProcess (const char *url,
                                                  Platform *platform,
                                                  ProcessLaunchInfo &launch_info,
-                                                 uint16_t &out_port)
+                                                 uint16_t *port)
 {
     Log *log (ProcessGDBRemoteLog::GetLogIfAllCategoriesSet (GDBR_LOG_PROCESS));
     if (log)
-        log->Printf ("GDBRemoteCommunication::%s(hostname=%s, in_port=%" PRIu16 ", out_port=%" PRIu16, __FUNCTION__, hostname ? hostname : "<empty>", in_port, out_port);
+        log->Printf ("GDBRemoteCommunication::%s(url=%s, port=%" PRIu16, __FUNCTION__, url ? url : "<empty>", port ? *port : uint16_t(0));
 
-    out_port = in_port;
     Error error;
     // If we locate debugserver, keep that located version around
     static FileSpec g_debugserver_file_spec;
     
     char debugserver_path[PATH_MAX];
     FileSpec &debugserver_file_spec = launch_info.GetExecutableFile();
     
     // Always check to see if we have an environment override for the path
if (debugserver_exists)
         // Start args with "debugserver /file/path -r --"
         debugserver_args.AppendArgument(debugserver_path);
 
 #if !defined(__APPLE__)
         // First argument to lldb-server must be mode in which to run.
         debugserver_args.AppendArgument("gdbserver");
 #endif
 
-        // If a host and port is supplied then use it
-        char host_and_port[128];
-        if (hostname)
-        {
-            snprintf (host_and_port, sizeof(host_and_port), "%s:%u", hostname, in_port);
-            debugserver_args.AppendArgument(host_and_port);
-        }
-        else
-        {
-            host_and_port[0] = '\0';
-        }
+        // If a url is supplied then use it
+        if (url)
+            debugserver_args.AppendArgument(url);
 
         // use native registers, not the GDB registers
         debugserver_args.AppendArgument("--native-regs");
 
         if (launch_info.GetLaunchInSeparateProcessGroup())
         {
             debugserver_args.AppendArgument("--setsid");
         }
 
         llvm::SmallString<PATH_MAX> named_pipe_path;
         Pipe port_pipe;
 
-        if (in_port == 0)
+        if (port != nullptr && *port == 0)
         {
-            if (host_and_port[0])
+            if (url)
             {
                 // Create a temporary file to get the stdout/stderr and redirect the
                 // output of the command into this file. We will later read this file
                 // if all goes well and fill the data into "command_output_ptr"
     
 #if defined(__APPLE__)
                 // Binding to port zero, we need to figure out what port it ends up
                 // using using a named pipe...
#endif
                 {
                     if (log)
                         log->Printf ("GDBRemoteCommunication::%s() unable to start listen thread: %s", __FUNCTION__, error.AsCString());
                     return error;
                 }
     
                 ConnectionFileDescriptor *connection = (ConnectionFileDescriptor *)GetConnection ();
                 // Wait for 10 seconds to resolve the bound port
-                out_port = connection->GetListeningPort(10);
-                if (out_port > 0)
+                *port = connection->GetListeningPort(10);
+                if (*port > 0)
                 {
                     char port_cstr[32];
-                    snprintf(port_cstr, sizeof(port_cstr), "127.0.0.1:%i", out_port);
+                    snprintf(port_cstr, sizeof(port_cstr), "127.0.0.1:%i", *port);
                     // Send the host and port down that debugserver and specify an option
                     // so that it connects back to the port we are listening to in this process
                     debugserver_args.AppendArgument("--reverse-connect");
                     debugserver_args.AppendArgument(port_cstr);
                 }
                 else
                 {
                     error.SetErrorString ("failed to bind to port 0 on 127.0.0.1");
#endif
 
         // Redirect STDIN, STDOUT and STDERR to "/dev/null".
         launch_info.AppendSuppressFileAction (STDIN_FILENO, true, false);
         launch_info.AppendSuppressFileAction (STDOUT_FILENO, false, true);
         launch_info.AppendSuppressFileAction (STDERR_FILENO, false, true);
         
         error = Host::LaunchProcess(launch_info);
         
-        if (error.Success() && launch_info.GetProcessID() != LLDB_INVALID_PROCESS_ID)
+        if (error.Success() &&
+            launch_info.GetProcessID() != LLDB_INVALID_PROCESS_ID &&
+            port != nullptr)
         {
             if (named_pipe_path.size() > 0)
             {
                 error = port_pipe.OpenAsReader(named_pipe_path, false);
                 if (error.Fail())
                     if (log)
                         log->Printf("GDBRemoteCommunication::%s() "
                                 "failed to open named pipe %s for reading: %s",
                                 __FUNCTION__, named_pipe_path.c_str(), error.AsCString());
             }
 
             if (port_pipe.CanWrite())
                 port_pipe.CloseWriteFileDescriptor();
             if (port_pipe.CanRead())
             {
                 char port_cstr[256];
                 port_cstr[0] = '\0';
                 size_t num_bytes = sizeof(port_cstr);
                 // Read port from pipe with 10 second timeout.
                 error = port_pipe.ReadWithTimeout(port_cstr, num_bytes,
                         std::chrono::seconds{10}, num_bytes);
                 if (error.Success())
                 {
                     assert(num_bytes > 0 && port_cstr[num_bytes-1] == '\0');
-                    out_port = StringConvert::ToUInt32(port_cstr, 0);
+                    *port = StringConvert::ToUInt32(port_cstr, 0);
                     if (log)
                         log->Printf("GDBRemoteCommunication::%s() "
                                 "debugserver listens %u port",
-                                __FUNCTION__, out_port);
+                                __FUNCTION__, *port);
                 }
                 else
                 {
                     if (log)
                         log->Printf("GDBRemoteCommunication::%s() "
                                 "failed to read a port value from pipe %s: %s",
                                 __FUNCTION__, named_pipe_path.c_str(), error.AsCString());
 

source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.h

SendInterrupt (Mutex::Locker &locker,
                    bool &timed_out);
 
     lldb::pid_t
     GetCurrentProcessID (bool allow_lazy = true);
 
     bool
     GetLaunchSuccess (std::string &error_str);
 
-    uint16_t
-    LaunchGDBserverAndGetPort (lldb::pid_t &pid, const char *remote_accept_hostname);
+    bool
+    LaunchGDBserverAndGetPort (const char *remote_accept_hostname,
+                               lldb::pid_t &pid,
+                               uint16_t &port,
+                               std::string &socket_name);
     
     bool
     KillSpawnedProcess (lldb::pid_t pid);
 
     //------------------------------------------------------------------
     /// Sends a GDB remote protocol 'A' packet that delivers program
     /// arguments to the remote server.
     ///

source/Plugins/Process/gdb-remote/GDBRemoteCommunicationClient.cpp

while (bytes_left > 0)
             bytes_left = 0;
         }
     }
 
     StringExtractorGDBRemote response;
     return SendPacketAndWaitForResponse (packet.GetData(), packet.GetSize(), response, false)  == PacketResult::Success;
 }
 
-uint16_t
-GDBRemoteCommunicationClient::LaunchGDBserverAndGetPort (lldb::pid_t &pid, const char *remote_accept_hostname)
+bool
+GDBRemoteCommunicationClient::LaunchGDBserverAndGetPort (const char *remote_accept_hostname,
+                                                         lldb::pid_t &pid,
+                                                         uint16_t &port,
+                                                         std::string &socket_name)
 {
     pid = LLDB_INVALID_PROCESS_ID;
+    port = 0;
+    socket_name.clear();
+
     StringExtractorGDBRemote response;
     StreamString stream;
     stream.PutCString("qLaunchGDBServer;");
     std::string hostname;
     if (remote_accept_hostname  && remote_accept_hostname[0])
         hostname = remote_accept_hostname;
     else
     {
         if (HostInfo::GetHostname(hostname))
         {
             // Make the GDB server we launch only accept connections from this host
             stream.Printf("host:%s;", hostname.c_str());
         }
         else
         {
             // Make the GDB server we launch accept connections from any host since we can't figure out the hostname
             stream.Printf("host:*;");
         }
     }
     const char *packet = stream.GetData();
     int packet_len = stream.GetSize();
 
     // give the process a few seconds to startup
     GDBRemoteCommunication::ScopedTimeout timeout (*this, 10);
-    
     if (SendPacketAndWaitForResponse(packet, packet_len, response, false) == PacketResult::Success)
     {
         std::string name;
         std::string value;
-        uint16_t port = 0;
+        StringExtractor extractor;
         while (response.GetNameColonValue(name, value))
         {
             if (name.compare("port") == 0)
                 port = StringConvert::ToUInt32(value.c_str(), 0, 0);
             else if (name.compare("pid") == 0)
                 pid = StringConvert::ToUInt64(value.c_str(), LLDB_INVALID_PROCESS_ID, 0);
+            else if (name.compare("socket_name") == 0)
+            {
+                extractor.GetStringRef().swap(value);
+                extractor.SetFilePos(0);
+                extractor.GetHexByteString(value);
+
+                socket_name = value;
             }
-        return port;
         }
-    return 0;
+        return true;
+    }
+    return false;
 }
 
 bool
 GDBRemoteCommunicationClient::KillSpawnedProcess (lldb::pid_t pid)
 {
     StreamString stream;
     stream.Printf ("qKillSpawnedProcess:%" PRId64 , pid);
     const char *packet = stream.GetData();

source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.h

 //===-- GDBRemoteCommunicationServerPlatform.h ------------------*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef liblldb_GDBRemoteCommunicationServerPlatform_h_
 #define liblldb_GDBRemoteCommunicationServerPlatform_h_
 
 #include "GDBRemoteCommunicationServerCommon.h"
 
+#include "lldb/Host/Socket.h"
+
 #include <set>
 
 namespace lldb_private {
 namespace process_gdb_remote {
 
 class GDBRemoteCommunicationServerPlatform :
     public GDBRemoteCommunicationServerCommon
 {
 public:
     typedef std::map<uint16_t, lldb::pid_t> PortMap;
 
-    GDBRemoteCommunicationServerPlatform();
+    GDBRemoteCommunicationServerPlatform(const Socket::SocketProtocol socket_protocol);
 
     virtual
     ~GDBRemoteCommunicationServerPlatform();
 
     Error
     LaunchProcess () override;
 
     // Set both ports to zero to let the platform automatically bind to 
public:
 
     bool
     FreePortForProcess (lldb::pid_t pid);
 
     void
     SetPortOffset (uint16_t port_offset);
 
 protected:
+    const Socket::SocketProtocol m_socket_protocol;
     Mutex m_spawned_pids_mutex;
     std::set<lldb::pid_t> m_spawned_pids;
     lldb::PlatformSP m_platform_sp;
 
     PortMap m_port_map;
     uint16_t m_port_offset;
 
     PacketResult
private:
 
     static bool
     ReapDebugserverProcess (void *callback_baton,
                             lldb::pid_t pid,
                             bool exited,
                             int signal,
                             int status);
 
+    static const FileSpec&
+    GetDomainSocketDir();
+
+    static FileSpec
+    GetDomainSocketPath(const char* prefix);
+
     //------------------------------------------------------------------
     // For GDBRemoteCommunicationServerPlatform only
     //------------------------------------------------------------------
     DISALLOW_COPY_AND_ASSIGN (GDBRemoteCommunicationServerPlatform);
 };
 
 } // namespace process_gdb_remote
 } // namespace lldb_private
 
 #endif  // liblldb_GDBRemoteCommunicationServerPlatform_h_

source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.cpp

 #include "GDBRemoteCommunicationServerPlatform.h"
 
 #include <errno.h>
 
 // C Includes
 // C++ Includes
 #include <cstring>
 #include <chrono>
+#include <mutex>
+#include <sstream>
 
 // Other libraries and framework includes
 #include "lldb/Core/Log.h"
+#include "lldb/Core/StreamGDBRemote.h"
 #include "lldb/Core/StreamString.h"
 #include "lldb/Core/StructuredData.h"
 #include "lldb/Host/Config.h"
 #include "lldb/Host/ConnectionFileDescriptor.h"
 #include "lldb/Host/Host.h"
+#include "lldb/Host/HostInfo.h"
 #include "lldb/Host/StringConvert.h"
 #include "lldb/Target/FileAction.h"
 #include "lldb/Target/Platform.h"
 #include "lldb/Target/Process.h"
 #include "lldb/Target/UnixSignals.h"
 
+#include "llvm/Support/FileSystem.h"
+
 // Project includes
 #include "Utility/StringExtractorGDBRemote.h"
 #include "Utility/UriParser.h"
 
 using namespace lldb;
 using namespace lldb_private;
 using namespace lldb_private::process_gdb_remote;
 
 //----------------------------------------------------------------------
 // GDBRemoteCommunicationServerPlatform constructor
 //----------------------------------------------------------------------
-GDBRemoteCommunicationServerPlatform::GDBRemoteCommunicationServerPlatform() :
+GDBRemoteCommunicationServerPlatform::GDBRemoteCommunicationServerPlatform(const Socket::SocketProtocol socket_protocol) :
     GDBRemoteCommunicationServerCommon ("gdb-remote.server", "gdb-remote.server.rx_packet"),
+    m_socket_protocol(socket_protocol),
     m_spawned_pids_mutex (Mutex::eMutexTypeRecursive),
     m_platform_sp (Platform::GetHostPlatform ()),
     m_port_map (),
     m_port_offset(0)
 {
     RegisterMemberFunctionHandler(StringExtractorGDBRemote::eServerPacketType_qC,
                                   &GDBRemoteCommunicationServerPlatform::Handle_qC);
     RegisterMemberFunctionHandler(StringExtractorGDBRemote::eServerPacketType_qGetWorkingDir,
#else
 
     std::string platform_scheme;
     std::string platform_ip;
     int platform_port;
     std::string platform_path;
     bool ok = UriParser::Parse(GetConnection()->GetURI().c_str(), platform_scheme, platform_ip, platform_port, platform_path);
     UNUSED_IF_ASSERT_DISABLED(ok);
     assert(ok);
-    Error error = StartDebugserverProcess (platform_ip.c_str(),
-                                           port,
+
+    std::string socket_name;
+    std::ostringstream url;
+
+    uint16_t* port_ptr = &port;
+    if (m_socket_protocol == Socket::ProtocolTcp)
+        url << platform_ip << ":" << port;
+    else
+    {
+        socket_name = GetDomainSocketPath("gdbserver").GetPath();
+        url << socket_name;
+        port_ptr = nullptr;
+    }
+
+    Error error = StartDebugserverProcess (url.str().c_str(),
                                            nullptr,
                                            debugserver_launch_info,
-                                           port);
+                                           port_ptr);
 
     lldb::pid_t debugserver_pid = debugserver_launch_info.GetProcessID();
 
 
     if (debugserver_pid != LLDB_INVALID_PROCESS_ID)
     {
         Mutex::Locker locker (m_spawned_pids_mutex);
         m_spawned_pids.insert(debugserver_pid);
         if (port > 0)
             AssociatePortWithProcess(port, debugserver_pid);
     }
     else
     {
         if (port > 0)
             FreePort (port);
     }
 
     if (error.Success())
     {
         if (log)
             log->Printf ("GDBRemoteCommunicationServerPlatform::%s() debugserver launched successfully as pid %" PRIu64, __FUNCTION__, debugserver_pid);
 
-        char response[256];
-        const int response_len = ::snprintf (response, sizeof(response), "pid:%" PRIu64 ";port:%u;", debugserver_pid, port + m_port_offset);
-        assert (response_len < (int)sizeof(response));
-        PacketResult packet_result = SendPacketNoLock (response, response_len);
+        StreamGDBRemote response;
+        response.Printf("pid:%" PRIu64 ";port:%u;", debugserver_pid, port + m_port_offset);
+        if (!socket_name.empty())
+        {
+            response.PutCString("socket_name:");
+            response.PutCStringAsRawHex8(socket_name.c_str());
+            response.PutChar(';');
+        }
 
+        PacketResult packet_result = SendPacketNoLock(response.GetData(), response.GetSize());
         if (packet_result != PacketResult::Success)
         {
             if (debugserver_pid != LLDB_INVALID_PROCESS_ID)
                 ::kill (debugserver_pid, SIGINT);
         }
         return packet_result;
     }
     else
if (!m_port_map.empty())
                 pair.second = LLDB_INVALID_PROCESS_ID;
                 return true;
             }
         }
     }
     return false;
 }
 
+const FileSpec&
+GDBRemoteCommunicationServerPlatform::GetDomainSocketDir()
+{
+    static FileSpec g_domainsocket_dir;
+    static std::once_flag g_once_flag;
+
+    std::call_once(g_once_flag, []() {
+        const char* domainsocket_dir_env = ::getenv("LLDB_DEBUGSERVER_DOMAINSOCKET_DIR");
+        if (domainsocket_dir_env != nullptr)
+            g_domainsocket_dir = FileSpec(domainsocket_dir_env, false);
+        else
+            HostInfo::GetLLDBPath(ePathTypeLLDBTempSystemDir, g_domainsocket_dir);
+    });
+
+    return g_domainsocket_dir;
+}
+
+FileSpec
+GDBRemoteCommunicationServerPlatform::GetDomainSocketPath(const char* prefix)
+{
+    llvm::SmallString<PATH_MAX> socket_path;
+    llvm::SmallString<PATH_MAX> socket_name((llvm::StringRef(prefix) + ".%%%%%%").str());
+
+    FileSpec socket_path_spec(GetDomainSocketDir());
+    socket_path_spec.AppendPathComponent(socket_name.c_str());
+
+    llvm::sys::fs::createUniqueFile(socket_path_spec.GetCString(), socket_path);
+    return FileSpec(socket_path.c_str(), false);
+}
+
 void
 GDBRemoteCommunicationServerPlatform::SetPortOffset (uint16_t port_offset)
 {
     m_port_offset = port_offset;
 }

source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

 #if defined (__APPLE__) && (defined (__arm__) || defined (__arm64__) || defined (__aarch64__))
         // On iOS, still do a local connection using a random port
         const char *hostname = "127.0.0.1";
         uint16_t port = get_random_port ();
 #else
         // Set hostname being NULL to do the reverse connect where debugserver
         // will bind to port zero and it will communicate back to us the port
         // that we will connect to
-        const char *hostname = NULL;
+        const char *hostname = nullptr;
         uint16_t port = 0;
 #endif
 
-        error = m_gdb_comm.StartDebugserverProcess (hostname,
-                                                    port,
+        StreamString url_str;
+        const char* url = nullptr;
+        if (hostname != nullptr)
+        {
+            url_str.Printf("%s:%u", hostname, port);
+            url = url_str.GetData();
+        }
+
+        error = m_gdb_comm.StartDebugserverProcess (url,
                                                     GetTarget().GetPlatform().get(),
                                                     debugserver_launch_info,
-                                                    port);
+                                                    &port);
 
         if (error.Success ())
             m_debugserver_pid = debugserver_launch_info.GetProcessID();
         else
             m_debugserver_pid = LLDB_INVALID_PROCESS_ID;
 
         if (m_debugserver_pid != LLDB_INVALID_PROCESS_ID)
             StartAsyncThread ();

tools/lldb-server/Acceptor.h

+//===-- Acceptor.h ----------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+#ifndef lldb_server_Acceptor_h_
+#define lldb_server_Acceptor_h_
+
+#include "lldb/Core/Connection.h"
+#include "lldb/Core/Error.h"
+#include "lldb/Host/Socket.h"
+
+#include <memory>
+#include <string>
+
+namespace llvm
+{
+    class StringRef;
+}
+
+namespace lldb_private {
+namespace lldb_server {
+
+class Acceptor
+{
+public:
+    virtual ~Acceptor() = default;
+
+    Error
+    Listen(int backlog);
+
+    Error
+    Accept(const bool child_processes_inherit, Connection *&conn);
+
+    static std::unique_ptr<Acceptor>
+    Create(llvm::StringRef name, const bool child_processes_inherit, Error &error);
+
+    Socket::SocketProtocol GetSocketProtocol() const;
+
+    // returns port number or 0 if error
+    uint16_t GetTCPLocalPort() const;
+
+private:
+    Acceptor(std::unique_ptr<Socket> &&listener_socket,
+             llvm::StringRef name);
+
+    const std::unique_ptr<Socket> m_listener_socket_up;
+    const std::string m_name;
+};
+
+} // namespace lldb_server
+} // namespace lldb_private
+
+#endif  // lldb_server_Acceptor_h_

tools/lldb-server/Acceptor.cpp

+//===-- Acceptor.cpp --------------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "Acceptor.h"
+
+#include "lldb/Core/StreamString.h"
+#include "lldb/Host/ConnectionFileDescriptor.h"
+#include "lldb/Host/common/TCPSocket.h"
+#include "lldb/Host/posix/DomainSocket.h"
+#include "llvm/ADT/StringRef.h"
+
+using namespace lldb;
+using namespace lldb_private;
+using namespace lldb_private::lldb_server;
+using namespace llvm;
+
+Error
+Acceptor::Listen(int backlog)
+{
+    return m_listener_socket_up->Listen(StringRef(m_name.c_str()),
+                                        backlog);
+}
+
+Error
+Acceptor::Accept(const bool child_processes_inherit, Connection *&conn)
+{
+    Socket* conn_socket = nullptr;
+    auto error = m_listener_socket_up->Accept(StringRef(m_name.c_str()),
+                                              child_processes_inherit,
+                                              conn_socket);
+    if (error.Success())
+        conn = new ConnectionFileDescriptor(conn_socket);
+
+    return error;
+}
+
+Socket::SocketProtocol
+Acceptor::GetSocketProtocol() const
+{
+    return m_listener_socket_up->GetSocketProtocol();
+}
+
+// returns port number or 0 if error
+uint16_t
+Acceptor::GetTCPLocalPort() const
+{
+    assert(GetSocketProtocol() == Socket::ProtocolTcp);
+    const TCPSocket& tcp_socket(static_cast<const TCPSocket&>(*m_listener_socket_up));
+    return tcp_socket.GetLocalPortNumber();
+}
+
+std::unique_ptr<Acceptor>
+Acceptor::Create(StringRef name, const bool child_processes_inherit, Error &error)
+{
+    error.Clear();
+
+    std::unique_ptr<Socket> listener_socket = nullptr;
+    std::string host_str;
+    std::string port_str;
+    int32_t port = INT32_MIN;
+    if (Socket::DecodeHostAndPort (name, host_str, port_str, port, &error))
+        listener_socket.reset(new TCPSocket(child_processes_inherit, error));
+    else
+        listener_socket.reset(new DomainSocket(child_processes_inherit, error));
+
+    if (error.Success())
+        return std::unique_ptr<Acceptor>(
+            new Acceptor(std::move(listener_socket), name));
+
+    return std::unique_ptr<Acceptor>();
+}
+
+Acceptor::Acceptor(std::unique_ptr<Socket> &&listener_socket,
+                   StringRef name)
+    : m_listener_socket_up(std::move(listener_socket)),
+      m_name(name.str())
+{
+}

tools/lldb-server/CMakeLists.txt

include_directories(
   ../../source/Plugins/Process/POSIX
   )
 endif ()
 
 include_directories(../../source)
 
 include(../../cmake/LLDBDependencies.cmake)
 
-if (BUILD_SHARED_LIBS )
-  add_lldb_executable(lldb-server
+    Acceptor.cpp
     lldb-gdbserver.cpp
     lldb-platform.cpp
     lldb-server.cpp
     LLDBServerUtilities.cpp
-    )
 
+if (BUILD_SHARED_LIBS )
   target_link_libraries(lldb-server liblldb)
   target_link_libraries(lldb-server ${LLDB_SYSTEM_LIBS})
 else()
-  add_lldb_executable(lldb-server
-    lldb-gdbserver.cpp
-    lldb-platform.cpp
-    lldb-server.cpp
-    LLDBServerUtilities.cpp
-    )
-
   # The Darwin linker doesn't understand --start-group/--end-group.
   if (LLDB_LINKER_SUPPORTS_GROUPS)
     target_link_libraries(lldb-server
                           -Wl,--start-group ${LLDB_USED_LIBS} -Wl,--end-group)
     target_link_libraries(lldb-server
                           -Wl,--start-group ${CLANG_USED_LIBS} -Wl,--end-group)
   else()
     target_link_libraries(lldb-server ${LLDB_USED_LIBS})

tools/lldb-server/lldb-gdbserver.cpp

 #include <unistd.h>
 #endif
 
 // C++ Includes
 
 // Other libraries and framework includes
 #include "llvm/ADT/StringRef.h"
 
-#include "lldb/Core/ConnectionMachPort.h"
 #include "lldb/Core/Error.h"
 #include "lldb/Core/PluginManager.h"
 #include "lldb/Host/ConnectionFileDescriptor.h"
 #include "lldb/Host/HostGetOpt.h"
-#include "lldb/Host/HostThread.h"
 #include "lldb/Host/OptionParser.h"
 #include "lldb/Host/Pipe.h"
 #include "lldb/Host/Socket.h"
 #include "lldb/Host/StringConvert.h"
-#include "lldb/Host/ThreadLauncher.h"
 #include "lldb/Target/Platform.h"
+#include "Acceptor.h"
 #include "LLDBServerUtilities.h"
 #include "Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h"
 #include "Plugins/Process/gdb-remote/ProcessGDBRemoteLog.h"
 
 #ifndef LLGS_PROGRAM_NAME
 #define LLGS_PROGRAM_NAME "lldb-server"
 #endif
 
 #ifndef LLGS_VERSION_STR
 #define LLGS_VERSION_STR "local_build"
 #endif
 
 using namespace llvm;
 using namespace lldb;
 using namespace lldb_private;
 using namespace lldb_private::lldb_server;
 using namespace lldb_private::process_gdb_remote;
 
-// lldb-gdbserver state
-
-namespace
-{
-HostThread s_listen_thread;
-    std::unique_ptr<ConnectionFileDescriptor> s_listen_connection_up;
-    std::string s_listen_url;
-}
-
 //----------------------------------------------------------------------
 // option descriptors for getopt_long_only()
 //----------------------------------------------------------------------
 
 static int g_debug = 0;
 static int g_verbose = 0;
 
 static struct option g_long_options[] =
handle_launch (GDBRemoteCommunicationServerLLGS &gdb_server, int argc, const char *const argv[])
     error = gdb_server.LaunchProcess ();
     if (error.Fail ())
     {
         fprintf (stderr, "error: failed to launch '%s': %s\n", argv[0], error.AsCString());
         exit(1);
     }
 }
 
-static lldb::thread_result_t
-ListenThread (lldb::thread_arg_t /* arg */)
-{
-    Error error;
-
-    if (s_listen_connection_up)
-    {
-        // Do the listen on another thread so we can continue on...
-        if (s_listen_connection_up->Connect(s_listen_url.c_str(), &error) != eConnectionStatusSuccess)
-            s_listen_connection_up.reset();
-    }
-    return nullptr;
-}
-
-static Error
-StartListenThread (const char *hostname, uint16_t port)
-{
-    Error error;
-    if (s_listen_thread.IsJoinable())
-    {
-        error.SetErrorString("listen thread already running");
-    }
-    else
-    {
-        char listen_url[512];
-        if (hostname && hostname[0])
-            snprintf(listen_url, sizeof(listen_url), "listen://%s:%i", hostname, port);
-        else
-            snprintf(listen_url, sizeof(listen_url), "listen://%i", port);
-
-        s_listen_url = listen_url;
-        s_listen_connection_up.reset (new ConnectionFileDescriptor ());
-        s_listen_thread = ThreadLauncher::LaunchThread(listen_url, ListenThread, nullptr, &error);
-    }
-    return error;
-}
-
-static bool
-JoinListenThread ()
-{
-    if (s_listen_thread.IsJoinable())
-        s_listen_thread.Join(nullptr);
-    return true;
-}
-
 Error
 WritePortToPipe(Pipe &port_pipe, const uint16_t port)
 {
     char port_str[64];
     const auto port_str_len = ::snprintf(port_str, sizeof(port_str), "%u", port);
 
     size_t bytes_written = 0;
     // Write the port number as a C string with the NULL terminator.
if (host_and_port && host_and_port[0])
 
         const std::string::size_type colon_pos = final_host_and_port.find (':');
         if (colon_pos != std::string::npos)
         {
             connection_host = final_host_and_port.substr (0, colon_pos);
             connection_port = final_host_and_port.substr (colon_pos + 1);
             connection_portno = StringConvert::ToUInt32 (connection_port.c_str (), 0);
         }
-        else
-        {
-            fprintf (stderr, "failed to parse host and port from connection string '%s'\n", final_host_and_port.c_str ());
-            display_usage (progname, subcommand);
-            exit (1);
-        }
 
-        std::unique_ptr<ConnectionFileDescriptor> connection_up;
+        std::unique_ptr<Connection> connection_up;
 
         if (reverse_connect)
         {
             // llgs will connect to the gdb-remote client.
 
             // Ensure we have a port number for the connection.
             if (connection_portno == 0)
             {
if (host_and_port && host_and_port[0])
             if (error.Fail ())
             {
                 fprintf (stderr, "error: failed to connect to client at '%s': %s", connection_url, error.AsCString ());
                 exit (-1);
             }
         }
         else
         {
-            // llgs will listen for connections on the given port from the given address.
-            // Start the listener on a new thread.  We need to do this so we can resolve the
-            // bound listener port.
-            StartListenThread(connection_host.c_str (), static_cast<uint16_t> (connection_portno));
-            printf ("Listening to port %s for a connection from %s...\n", connection_port.c_str (), connection_host.c_str ());
-
-            // If we have a named pipe to write the port number back to, do that now.
-            if (named_pipe_path && named_pipe_path[0] && connection_portno == 0)
-            {
-                const uint16_t bound_port = s_listen_connection_up->GetListeningPort (10);
-                if (bound_port > 0)
-                {
-                    error = writePortToPipe (named_pipe_path, bound_port);
-                    if (error.Fail ())
-                    {
-                        fprintf (stderr, "failed to write to the named pipe \'%s\': %s", named_pipe_path, error.AsCString());
-                    }
-                }
-                else
-                {
-                    fprintf (stderr, "unable to get the bound port for the listening connection\n");
-                }
+            std::unique_ptr<Acceptor> acceptor_up(Acceptor::Create(final_host_and_port, false, error));
+            if (error.Fail())
+                fprintf(stderr, "failed to create acceptor: %s", error.AsCString());
+                exit(1);
+            error = acceptor_up->Listen(1);
+            if (error.Fail())
+                fprintf(stderr, "failed to listen: %s\n", error.AsCString());
+                exit(1);
             }
-
-            // If we have an unnamed pipe to write the port number back to, do that now.
-            if (unnamed_pipe_fd >= 0 && connection_portno == 0)
+            if (acceptor_up->GetSocketProtocol() == Socket::ProtocolTcp &&
+                connection_portno == 0)
             {
-                const uint16_t bound_port = s_listen_connection_up->GetListeningPort(10);
+                const uint16_t bound_port = acceptor_up->GetTCPLocalPort();
                 if (bound_port > 0)
                 {
-                    error = writePortToPipe(unnamed_pipe_fd, bound_port);
-                    if (error.Fail())
+                    // If we have a named pipe to write the port number back to, do that now.
+                    if (named_pipe_path && named_pipe_path[0])
+                    {
+                        error = writePortToPipe (named_pipe_path, bound_port);
+                        if (error.Fail ())
+                            fprintf (stderr, "failed to write to the named pipe \'%s\': %s",
+                                     named_pipe_path, error.AsCString());
+                    }
+                    // If we have an unnamed pipe to write the port number back to, do that now.
+                    else if (unnamed_pipe_fd >= 0)
                     {
+                        error = writePortToPipe(unnamed_pipe_fd, bound_port);
+                        if (error.Fail())
                             fprintf(stderr, "failed to write to the unnamed pipe: %s",
                                     error.AsCString());
                     }
                 }
                 else
                 {
-                    fprintf(stderr, "unable to get the bound port for the listening connection\n");
+                    fprintf (stderr, "unable to get the bound port for the listening connection\n");
                 }
             }
 
-            // Join the listener thread.
-            if (!JoinListenThread ())
-            {
-                fprintf (stderr, "failed to join the listener thread\n");
-                display_usage (progname, subcommand);
-                exit (1);
-            }
-
-            // Ensure we connected.
-            if (s_listen_connection_up)
-                connection_up = std::move(s_listen_connection_up);
-            else
+            Connection* conn = nullptr;
+            error = acceptor_up->Accept(false, conn);
+            if (error.Fail())
             {
-                fprintf (stderr, "failed to connect to '%s': %s\n", final_host_and_port.c_str (), error.AsCString ());
-                display_usage (progname, subcommand);
-                exit (1);
+                printf ("failed to accept new connection: %s\n", error.AsCString());
+                exit(1);
             }
+            connection_up.reset(conn);
         }
         error = gdb_server.InitializeConnection (std::move(connection_up));
         if (error.Fail())
         {
             fprintf(stderr, "Failed to initialize connection: %s\n", error.AsCString());
             exit(-1);
         }
         printf ("Connection established.\n");

tools/lldb-server/lldb-platform.cpp

 #include "lldb/Host/ConnectionFileDescriptor.h"
 #include "lldb/Host/FileSpec.h"
 #include "lldb/Host/FileSystem.h"
 #include "lldb/Host/HostGetOpt.h"
 #include "lldb/Host/OptionParser.h"
 #include "lldb/Host/common/TCPSocket.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/FileUtilities.h"
+#include "Acceptor.h"
 #include "LLDBServerUtilities.h"
 #include "Plugins/Process/gdb-remote/GDBRemoteCommunicationServerPlatform.h"
 #include "Plugins/Process/gdb-remote/ProcessGDBRemoteLog.h"
 
 using namespace lldb;
 using namespace lldb_private;
 using namespace lldb_private::lldb_server;
 using namespace lldb_private::process_gdb_remote;
#endif
     if (listen_host_port.empty())
         show_usage = true;
     
     if (show_usage || option_error)
     {
         display_usage(progname, subcommand);
         exit(option_error);
     }
-    
-    Socket *socket = nullptr;
     const bool children_inherit_listen_socket = false;
-
     // the test suite makes many connections in parallel, let's not miss any.
-    // The highest this should get reasonably is a function of the number 
-    // of target CPUs.  For now, let's just use 100
+    // The highest this should get reasonably is a function of the number
+    // of target CPUs. For now, let's just use 100.
     const int backlog = 100;
-    std::unique_ptr<TCPSocket> listening_socket_up(new TCPSocket(children_inherit_listen_socket, error));
+
+    std::unique_ptr<Acceptor> acceptor_up(Acceptor::Create(listen_host_port, children_inherit_listen_socket, error));
     if (error.Fail())
     {
-        fprintf(stderr, "failed to create socket: %s", error.AsCString());
+        fprintf(stderr, "failed to create acceptor: %s", error.AsCString());
         exit(socket_error);
     }
 
-    error = listening_socket_up->Listen(listen_host_port.c_str(), backlog);
+    error = acceptor_up->Listen(backlog);
     if (error.Fail())
     {
-        printf("error: %s\n", error.AsCString());
+        printf("failed to listen: %s\n", error.AsCString());
         exit(socket_error);
     }
-    if (port_file)
+    if (port_file && acceptor_up->GetSocketProtocol() == Socket::ProtocolTcp)
     {
-        error = save_port_to_file(listening_socket_up->GetLocalPortNumber(), port_file);
+        error = save_port_to_file(acceptor_up->GetTCPLocalPort(), port_file);
         if (error.Fail())
         {
             fprintf(stderr, "failed to write port to %s: %s", port_file.GetPath().c_str(), error.AsCString());
             return 1;
         }
     }
 
     do {
-        GDBRemoteCommunicationServerPlatform platform;
+        GDBRemoteCommunicationServerPlatform platform(acceptor_up->GetSocketProtocol());
         
         if (port_offset > 0)
             platform.SetPortOffset(port_offset);
 
         if (!gdbserver_portmap.empty())
         {
             platform.SetPortMap(std::move(gdbserver_portmap));
         }
 
         const bool children_inherit_accept_socket = true;
-        socket = nullptr;
-        error = listening_socket_up->Accept(listen_host_port.c_str(), children_inherit_accept_socket, socket);
+        Connection* conn = nullptr;
+        error = acceptor_up->Accept(children_inherit_accept_socket, conn);
         if (error.Fail())
         {
             printf ("error: %s\n", error.AsCString());
             exit(socket_error);
         }
         printf ("Connection established.\n");
         if (g_server)
         {
             // Collect child zombie processes.
             while (waitpid(-1, nullptr, WNOHANG) > 0);
             if (fork())
             {
                 // Parent doesn't need a connection to the lldb client
-                delete socket;
-                socket = nullptr;
+                delete conn;
 
                 // Parent will continue to listen for new connections.
                 continue;
             }
             else
             {
                 // Child process will handle the connection and exit.
                 g_server = 0;
                 // Listening socket is owned by parent process.
-                listening_socket_up.release();
+                acceptor_up.release();
             }
         }
         else
         {
             // If not running as a server, this process will not accept
             // connections while a connection is active.
-            listening_socket_up.reset();
+            acceptor_up.reset();
         }
-        platform.SetConnection (new ConnectionFileDescriptor(socket));
+        platform.SetConnection (conn);
 
         if (platform.IsConnected())
         {
             // After we connected, we need to get an initial ack from...
             if (platform.HandshakeWithClient())
             {
                 bool interrupt = false;
                 bool done = false;